bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 4887: Mitochondrial SOD2 is the mainstay to protect the stemness-featured glioblastoma cells against drug-induced reactive oxygen stress
Authors: Chang Kwang-Yu , Chien Chia-Hung , Chu Jui-Mei , Chung Pei-Hsuan , Liu Ming-Sheng , Chuang Jian-Ying
Published: August 2018

Glioblastoma (GBM) is a highly aggressive primary brain tumor with presence of stemness-featured cells that are prone to survive from cancer treatment. We reported Sp1-induced SOD2 was associated with the process to acquire temozolomide (TMZ) resistance that the significance remained to be elucidated. Resistant models were established through long-term coincubation with TMZ in GBM cell lines, which expressed significantly higher stemness properties in extreme limiting dilution analysis (ELDA) and serial transplantation. These cells also showed increased expression of SOD2. Enrichment of stemness-featured cells by spheroid culturing or by CD133-positive cells selection resulted in increased SOD2, suggesting their associations. The impact of the protein to glioma stem cells (GSCs) was then studied through SOD2 RNA interference (RNAi), displaying downregulated stemness features in the knockdown models. Functional studies of the resistant cells showed superior scavenging ability in TMZ- or H2O2-induced ROS that would be dysfunctioned in pretreatment with SOD2 RNAi. In addition, co-treatment with the reagents over the knockdown cells resulted in enhancement of apoptosis as well as inhibition in tumor spheroid culture and cell clonogenic formation, suggesting re-sensitization to the drug. By establishing in vivo model from patient derived xenograft implantation that was obtained from clinical resistant disease, the mouse receiving combination treatment with TMZ and SOD inhibitor had lower tumor proliferation comparing to those receiving TMZ alone. These data indicate that there was an association between SOD2 and the stemness features, suggesting the protein to play important roles in regulation of GSCs behavior. Down-regulation of SOD2 levels may thus be a potential therapeutic strategy for modulating stemness properties of GSCs, making these cells more susceptive to the chemo-therapeutic agent.

Citation Format: Kwang-Yu Chang, Chia-Hung Chien, Jui-Mei Chu, Pei-Hsuan Chung, Ming-Sheng Liu, Jian-Ying Chuang. Mitochondrial SOD2 is the mainstay to protect the stemness-featured glioblastoma cells against drug-induced reactive oxygen stress [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4887.
Abstract 4890: Understanding the crosstalk between glycosylation and drug resistance
Authors: Thulasiraman Padmamalini , Kerr Kelbie
Published: August 2018

Although great progress has been made in the treatment of breast cancer, resistance to chemotherapeutic drugs is a problem facing current cancer research, promoting the need to understand the molecular mechanisms involved in breast cancer and identify future targeted therapy. One of the mechanisms by which chemoresistance is attained in cancer cells is mediated through the expression of MDR-related glycoproteins (MRPs). These transmembrane proteins efflux drugs across the plasma membrane, conferring resistance of cancer cells to anticancer drugs. Elevated expression of Multidrug Resistance Protein 1 (MRP1) has been associated with poor prognosis and survival rate among breast cancer patients. Acquiring drug resistance has been correlated to the emergence of metastasis, accounting for the progression of the disease. Altered cell-surface glycosylation is a common feature of cancer initiation and progression. During glycosylation, the MRP1 undergoes N-linked glycosylation but it is unclear how glycosylation impacts the drug transport activity. To examine the crosstalk between MRP1 and Neuraminidase 1 (Neu1), the enzyme that catalyzes the removal of sialic acid residues from glycoproteins, we initiated our studies using plant derived natural product honokiol to examine the effect of honokiol on Neu1. In this study, we demonstrated that honokiol suppressed Neu1 in two breast cancer cell lines using Western Blot Analysis. To determine whether there is a link between Neu1 and MRP1 in improving the efficacy of doxorubicin-facilitated growth suppression, we treated the breast cancer cells with Neu1 inhibitor, Oseltamivir Phosphate (OP) and demonstrated that at 600 ug/ml and 800 ug/ml, OP suppressed breast cancer cell growth. OP in combination with doxorubicin reduced growth of breast cancer cells and enhanced the efficacy of doxorubicin-mediated growth inhibition. Future studies are underway to examine the effect of OP and honokiol on the glycosylation of MRP1. We propose that these studies will lead to the understanding on how glycosylation of MRP1 contributes to the transport of chemotherapeutic agents and eventually to the spread of the disease.

Citation Format: Padmamalini Thulasiraman, Kelbie Kerr. Understanding the crosstalk between glycosylation and drug resistance [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4890.
Abstract 4892: Del-1 promotes the proliferation and migration of tamoxifen-resistant breast cancer
Authors: Chae Yee Soo , Kim Jong Gwang , Jeong Jae-Hwan , Lee Soo Jung , Lee Jeeyeon , Jung Jin Hyang , Park Ho Yong , Baek Moon-Chang , J Senten Richard , Park Ji Young
Published: August 2018

Background: We previously demonstrated a prognostic role of exosomal Del-1 with breast cancer patients. However, the mechanisms of Del-1 expression are barely understood. Development of resistance to tamoxifen is an important clinical issue in the treatment of breast cancer. Accordingly, we investigated the function of Del-1 in tamoxifen-resistant (TAMR) breast cancer cell line and tumor specimens.

Materials and Methods: Del-1 expression in MCF7 and TAMR MCF7 cells was performed by quantitative RT-PCR, western blot, and ELISA. The effects of Del-1 with RNA interference on proliferation, migration and invasion of TAMR MCF7 cells were observed by MTT, wound healing and Matrigel transwell assay. Meanwhile, the tumoral expression of Del-1 was determined immunohistochemistry (IHC) from 10 tamoxifen resistant-breast cancer patients. Tumor tissue before (tamoxifen sensitive) and after tamoxifen resistance were assessed.

Results: Del-1 was highly expressed in TAMR MCF7 cells compared to MCF7 cells (p<0.001). And the expression of secretory del-1 was also increased in the culture media of TAMR MCF7 cells. Moreover, down-regulation of Del-1 significantly inhibited the proliferation and migration of TAMR MCF7 cells. There was no difference in the invasion of TAMR MCF7 cells. Increased Del-1 expression was preferentially observed in in TAMR tumor tissues when compared to tamoxifen sensitive or normal breast tissue.

Conclusion: Prominent expression of Del-1 in TAMR MCF7 cells was associated with the proliferation and migration of TAMR MCF7 cells. And the tumoral expression of Del-1 was also significantly associated with tamoxifen resistance. These results suggest that the expression of Del-1 promote tamoxifen resistance in breast cancer cells and could be a novel target for anti-breast cancer treatment.

Citation Format: Yee Soo Chae, Jong Gwang Kim, Jae-Hwan Jeong, Soo Jung Lee, Jeeyeon Lee, Jin Hyang Jung, Ho Yong Park, Moon-Chang Baek, Senten Richard J, Ji Young Park. Del-1 promotes the proliferation and migration of tamoxifen-resistant breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4892.
Abstract 4895: Human ATP-binding cassette proteins ABCB1 and ABCG2 confer resistance to histone deacetylase 6 inhibitor ricolinostat (ACY-1215) in cancer cell lines
Authors: Hsiao Sung-Han , Vahedi Shahrooz , Ambudkar Suresh V. , Wu Chung-Pu
Published: August 2018

Histone deacetylase 6 (HDAC6), localized primarily in the cytoplasm, is responsible for the deacetylation of non-histone substrates such as α-tubulin and heat shock protein 90 (Hsp90). HDAC6 has recently emerged as an important epigenetic therapeutic target for cancer, and much effort has been invested into developing novel inhibitors of HDAC6. Ricolinostat (ACY-1215) is the first safe and well tolerated inhibitor of HDAC6 that has progressed into human clinical trials, both as a single agent and in combination therapy. Ricolinostat is currently under evaluation in phase I and II clinical trials in patients with multiple myeloma, relapsed or refractory lymphoid malignancies, relapsed chronic lymphocytic leukemia, unresectable or metastatic breast cancer and for the treatment of gynecological cancer. The overexpression of ATP-binding cassette (ABC) drug transporters ABCB1 and ABCG2 in cancer cells is often associated with the development of multidrug resistance (MDR) phenotype and poor clinical outcome in patients with metastatic breast cancer, chronic lymphocytic leukemia or relapsed multiple myeloma. In this study, we report that ABCB1 and ABCG2 are capable of actively transporting and conferring resistance to ricolinostat. Moreover, we demonstrated that the efficacy of ricolinostat on the activity of HDAC6 and drug-induced apoptosis was significantly reduced in ABCB1- and ABCG2-overexpressing cancer cells, which can be fully restored by an competitive inhibitor of ABCB1 or ABCG2.Our finding is supported by biochemical data and a docking analysis of ricolinostat in the drug-binding pocket of ABCB1 and ABCG2. Taken together, our study indicate that the overexpression ABCB1 or ABCG2 in cancer cells may potentially play a significant role in the development of resistance to ricolinostat in cancer cells.

Citation Format: Sung-Han Hsiao, Shahrooz Vahedi, Suresh V. Ambudkar, Chung-Pu Wu. Human ATP-binding cassette proteins ABCB1 and ABCG2 confer resistance to histone deacetylase 6 inhibitor ricolinostat (ACY-1215) in cancer cell lines [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4895.
Abstract 4896: The role of SLC7A5 (LAT1) in endocrine therapy-resistant breast cancer
Authors: Sevigny Catherine M. , Sengupta Surojeet , Luo Zhexun , Jin Lu , Pearce Dominic , Clarke Robert
Published: August 2018

Breast cancer is the leading cancer diagnosis for women in the United States. Endocrine therapies, such as tamoxifen and aromatase inhibitors, are used to treat the estrogen receptor-positive (ER+) breast cancers that comprise 70% of all new cases. Unfortunately, emergence of resistance to these therapies presents a major clinical challenge. Cancer cells can adapt to dysregulate the bioenergetics of cellular metabolism and evade cell death. Solute carrier family 7 member 5 (SLC7A5 or LAT1) is expressed across the cell membrane and is a transporter of large, neutral amino acids (such as leucine or tyrosine) supporting cell proliferation. Using LCC9 breast cancer cells that are resistant to tamoxifen and fulvestrant, we studied the role of LAT1 in endocrine therapy-resistant cells as compared to sensitive MCF7 breast cancer cells. SLC7A5 expression was upregulated by estrogen in MCF7 cells that was blocked in the presence of fulvestrant treatment. A significant 2.75-fold upregulation of SLC7A5 protein and 71-fold upregulation of SLC7A5 mRNA was found in LCC9 cells (as compared with MCF7 cells) without any estrogen regulation. Fulvestrant treatment did not significantly alter SLC7A5 mRNA or protein expression. These data suggest that higher levels of SLC7A5 in resistant cells may help in transporting key amino acids from their microenvironment to support cell growth. Inhibiting the functions of SLC7A5 using a pharmacologic inhibitor, JPH203, or depleting its expression by using siRNA led to significant growth suppression of LCC9 cells. Cell cycle analysis revealed that SLC7A5 depletion increased G1 phase of cell cycle and reduced S phase cells. In five publicly available data sets, of estrogen receptor-positive and tamoxifen-treated breast cancer patients, high expression of SLC7A5 was associated with worse prognosis. Endocrine therapy resistance is partly driven by autophagy in breast cancer cells. We depleted SLC7A5 expression in LCC9s to better understand the role of this transporter in autophagy. This study uncovers a novel adaptive mechanism in endocrine therapy-resistant breast cancer cells that is facilitated by increased SLC7A5 mediated transport of large neutral amino acids enabling them to supplement their increased metabolic needs and promoting cell growth. Therefore, blocking the functions of SLC7A5, perhaps in conjunction with inhibition of autophagy, may offer an avenue of potential therapeutic intervention in endocrine therapy-resistant breast cancers.

Citation Format: Catherine M. Sevigny, Surojeet Sengupta, Zhexun Luo, Lu Jin, Dominic Pearce, Robert Clarke. The role of SLC7A5 (LAT1) in endocrine therapy-resistant breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4896.
Abstract 4898: Reduction of TGFBR2 in osteoblasts by enzalutamide causes drug resistance in prostate cancer bone metastasis
Authors: Ark Alexandra Vander , Woodford Erica , Meng Xiangqi , Ganguly Sourik , Zhang Xiaotun , Madaj Zachary , Li Xiaohong
Published: August 2018

In the United States, over 80% of prostate cancer patients die with bone metastases. Second-line hormonal therapies, such as enzalutamide, only improve overall patient survival by a few months in about 50% of patients, and almost all patients develop drug resistance. Thus, there is an urgent need to determine the mechanisms of drug resistance in order to provide better treatments for prostate cancer bone metastasis. Enzalutamide is a small-molecule inhibitor of the androgen receptor. Our study showed that although enzalutamide inhibited the tumor growth of castration-resistant prostate cancer C4-2B cells when xenografted subcutaneously, it had no effect on the growth of C4-2B tumors in the bone or on the development of bone lesions. These data suggested a crucial role of the microenvironment in enzalutamide resistance in prostate cancer bone metastasis. To dissect the role of enzalutamide on the bone microenvironment, we treated bone cells, both osteoblasts and osteoclasts, with enzalutamide. We found that enzalutamide significantly and specifically reduced the TGF-β type II receptor (TGFBR2) protein in osteoblasts. This observation was also confirmed in prostate cancer bone metastatic tissue microarray, in which we performed immunohistochemistry and found a significant decrease of TGFBR2 expression specifically in cancer-associated osteoblasts from patients who had undergone treatment with second-line hormonal therapies, either enzalutamide or abiraterone. Statistical analysis showed that the decrease of TGFBR2 in cancer-associated osteoblasts was a causative effect from the hormonal therapies. To determine the role of TGFBR2 in the osteoblasts during bone metastasis, we used a mouse model (Tgfbr2Col1CreERT KO) with inducible Tgfbr2 knockout specifically in the osteoblasts. We found that loss of TGFBR2 in osteoblasts significantly promoted prostate cancer bone metastasis. Together, our data showed for the first time that reduction of TGFBR2 in osteoblasts by enzalutamide causes resistance to the drug in prostate cancer bone metastasis.

Citation Format: Alexandra Vander Ark, Erica Woodford, Xiangqi Meng, Sourik Ganguly, Xiaotun Zhang, Zachary Madaj, Xiaohong Li. Reduction of TGFBR2 in osteoblasts by enzalutamide causes drug resistance in prostate cancer bone metastasis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4898.
Abstract 4902: Oxidized low-density lipoprotein is a potentially potent mediator of proteasome inhibitor resistance in multiple myeloma
Authors: Medina Edward A. , Esparza Javier , Polusani Srikanth , Cortez Valerie , Nguyen Huynh N. , Velagaleti Gopalrao V. , Fan Hongxin Fan , Kinney Marsha C. , Asmis Reto
Published: August 2018

Multiple myeloma (MM) is a malignancy of plasma cells that accumulate in the bone marrow. While treatment advances, particularly proteasome inhibitors (PIs) and immunomodulatory drugs, have improved survival, MM is incurable. Obesity and insulin resistance are established risk factors for MM mortality. Oxidized low-density lipoprotein (OxLDL), a key atherogenic factor that is elevated in obesity, has emerged as a risk factor for the development and progression of some solid cancers, and it has been shown to stimulate pro-oncogenic signaling; its role in MM is unexplored. We evaluated the influence of OxLDL on MM cell killing by chemotherapeutics used to treat MM. OxLDL, at concentrations within the range reported for patients with metabolic syndrome, suppressed MM cell killing by the therapeutic PIs bortezomib and ixazomib. Native low-density lipoprotein (nLDL) did not affect the anti-MM effects of these PIs, which suggests that the oxidative modification of lipids or apolipoprotein in OxLDL is the mediator of cytoprotection. OxLDL did not affect MM cell killing by other agents with distinct targets such as the immunomodulatory drug lenolinamide and doxorubicin. OxLDL appeared to restore proteasome activity as evidenced by its suppression of bortezomib-induced accumulation of ubiquinated proteins and pro-apoptotic unfolded protein response signaling. The cytoprotective effects of OxLDL were suppressed when lipid hydroperoxides (LOOHs) associated with the lipoprotein were specifically reduced by pretreatment with the glutathione-dependent selenoperoxidase mimetic ebselen. Finally, immunohistochemical analysis of bone marrow biopsy samples from newly diagnosed MM patients demonstrated the presence of OxLDL in macrophages/histiocytes scattered among MM cells. Our findings suggest that OxLDL may be a potent mediator of chemoresistance to therapeutic PIs in obese/insulin-resistant MM patients. OxLDL appears to counteract the anti-MM effects of PIs through LOOH-mediated restoration of proteasome activity, which is significant since LDL is the major carrier of LOOHs in the plasma. Our findings raise the potential benefit of LDL cholesterol-lowering therapy, or pharmacologic targeting of intracellular pathways used by OxLDL, to increase the efficacy of therapeutic PIs and improve the survival of obese/insulin-resistant MM patients.

Citation Format: Edward A. Medina, Javier Esparza, Srikanth Polusani, Valerie Cortez, Huynh N. Nguyen, Gopalrao V. Velagaleti, Hongxin Fan Fan, Marsha C. Kinney, Reto Asmis. Oxidized low-density lipoprotein is a potentially potent mediator of proteasome inhibitor resistance in multiple myeloma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4902.
Abstract 4905: Utility of human FcRn transgenic mice for preclinical screening of immunotherapeutics
Authors: Christianson Gregory J. , Lowell Emily , Lutz Cat
Published: August 2018

Preclinical assessment is required for the growing number of immunotherapeutics in development. Clinically relevant pharmacokinetic analysis can be achieved by using transgenic mice that uniquely express the human Fc receptor neonatal (hFcRn). To demonstrate the utility of the human FcRn Tg mouse model platform, three immunotherapeutics (pembrolizumab, ipilimumab, and belatacept) were administered IV to Tg32, Tg276, FcRn null, and B6 wild type mice. The mice were blood sampled (25 µL) at 1, 3, 5, 7, 9, 12, 16, 19, 22, 26, and 30 days. Immunotherapeutic plasma concentations, assessed by human IgG ELISA, were pharmacokinetically analyzed. Tg32 mice yielded half-life values for these immunotherapeutics with ranges that mimicked patient data. Though reduced in scale, Tg276 mice also produced half-life data that correlated with the established human half-life data for pembrolizumab, ipilimumab, and belatacept. These results confirm that the human FcRn Tg model platform can be broadly applied to preclinical pharmacokinetic screening of mAb and Fc-fusion based immunotherapeutics.

Citation Format: Gregory J. Christianson, Emily Lowell, Cat Lutz. Utility of human FcRn transgenic mice for preclinical screening of immunotherapeutics [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4905.
Abstract 4906: Effect of gender on the rodent pharmacokinetics of ON 123300, a dual inhibitor of ARK5 and CDK4/6, for the treatment of cancer
Authors: Ren Chen , Mudunuru Jennypher , Taft David , Maniar Manoj
Published: August 2018

Purpose: To evaluate gender differences in the metabolism of ON 123300 in rats in vitro and in vivo. ON 123300, a novel small molecule dual inhibitor of the c-MYC activated kinases ARK5 and CDK4/6, is being developed by Onconova Therapeutics, Inc. as a novel anti-cancer drug candidate.

Methods: In vitro metabolism experiments were performed in rat liver microsomes from male and female donors. ON 123300 was incubated with microsomes, and samples were withdrawn at specified times over 60 minutes and, immediately quenched and centrifuged. The supernatant was analyzed for ON 123300 and its metabolites by HPLC. An in vivo pharmacokinetic study was performed in male and female SD rats. ON 123300 was administered as a single oral dose (100 mg/kg), and blood samples were collected over 24 hours. ON 123300 concentrations were measured by LC-MS/MS. Pharmacokinetic parameters were estimated by non-compartmental analysis.

Results: The results are provided in Table 1. ON 123300 displayed more rapid microsomal degradation in vitro (increase of Clint) in males compared to females. This translated into a significantly higher exposure of ON 123300 (3 fold increase of AUC) following oral administration to female rats. Based on these results, the higher plasma concentrations observed in females can be primarily attributed to reduced hepatic clearance compared to males.

Conclusions: Gender differences in pharmacokinetics and pharmacodynamics can potentially impact the design of safe and effective dosing regimens for treatments. This investigation demonstrated a significantly lower metabolism of ON 123300 in female rats, which resulted in dramatically high systemic exposure. Additional testing is warranted to assess the potential clinical implications of these findings.

Table 1. ON 123300 In Vitro and In Vivo Pharmacokinetic Parameters

In Vitro Metabolism (n = 2/group)In Vivo Pharmacokinetics (n = 5/group)Parameter (mean)MalesFemalesParameter (mean± SD)MalesFemalest1/2 (min)10.838.2Tmax (hr)2.3 ± 1.60.6 ± 0.2Clint (ml/min/mg)13036.7Cmax (ng/ml)321 ± 66.01253 ± 660Predicted In Vivo Cl(ml/min/kg)a239.267.5AUC0-∞ (ng-hr/ml)1803 ± 7575520 ± 2163Cl/F (ml/min/kg)1116 ± 474390 ± 269t1/2 (hr)1.9 ± 0.503.0 ± 0.5 apredicted from venous equilibration model assuming rat blood flow = 13.8 ml/min, 99% protein binding and blood:plasma ratio = 1 Citation Format: Chen Ren, Jennypher Mudunuru, David Taft, Manoj Maniar. Effect of gender on the rodent pharmacokinetics of ON 123300, a dual inhibitor of ARK5 and CDK4/6, for the treatment of cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4906.
Abstract 4908: Exemestane worsens everolimus-associated stomatitis in cancer patients
Authors: Lima Vladmir C. de , Lima Matheus H. de , Alves Fabio A. , Hajj Gláucia N.
Published: August 2018

Everolimus is an antitumor drug usually indicated for the treatment of breast, kidney and neuroendocrine malignancies that inhibits the activation of the mammalian Target of Rapamycin (mTOR). Despite the efficacy and success of the treatment, side effects are not uncommon, and stomatitis is quite prevalent. mTOR inhibitor associated stomatitis (mIAS) is described as ulcerated aphthous-like lesions associated with mTOR inhibitors use. mIAS may cause severe pain, leading to nutritional deficiency and general health decline, besides drug dose reduction or suspension. Clinical observation suggested mIAS to be more common among breast cancer patients. Thus, we hypothesized that exemestane could contribute to increase everolimus toxicity in the oral mucosa. We prospectivelly collected clinical data from patients who used everolimus, associated or not with exemestane, from March 2016 to September 2017, and correlated them with information regarding mIAS (date of onset, number of lesions in the oral cavity, grading). We also performed in vitro experiments with Dysplastic Oral Keratinocytes (DOK). Cells were treated with vehicle, everolimus, exemestane or the combination of everolimus and exemestane. Drug induced citotoxicity was evaluated by MTT assay and migration inhibition by scratch wound healing assay. All assays were done in triplicate. Frequencies were compared by Fisher's exact or McNemar test. Log-rank and Wilcoxon tests were employed to compare time to mIAS development. Multivariate ANOVA was used to compare results from in vitro experiments. SPSS and Image J were used to make all statistical analysis. One hundred and thirty patients were evaluated. Mostly were females, with mean age of 60 years, and had previously treated advanced stage (IV) breast cancer. 30.3% developed mIAS. Breast cancer patients (treated with exemestane plus everolimus) had 2.29 higher chance to develop mIAS when compared to neuroendocrine tumos patients (treated with everolimus alone). In vitro experiments showed that the association of everolimus and exemestane increased cell death and migration (wound healing) inhibition of DOK in comparison with cells treated with everolimus or exemestane alone. The clinical data suggests that exemestane increases the risk of developing mIAS, and the in vitro experiments reinforces the idea that exemestane may enhance oral mucosa toxicity mediated by everolimus.

Citation Format: Vladmir C. de Lima, Matheus H. de Lima, Fabio A. Alves, Gláucia N. Hajj. Exemestane worsens everolimus-associated stomatitis in cancer patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4908.
Abstract 4913: A PK/PD model quantitatively describes inhibition and down-regulation of p90RSK by ERK inhibitor AZD0364
Authors: Gibbons Francis D. , Sandin Linda , Hanson Lyndsey , Whiteley Rebecca , Farrington Paul , Lindsay Nicola , Davies Emma , Pease J Elizabeth , Flemington Vikki
Published: August 2018

ERK1/2 is a key protein in the MAPK pathway, regulating phenotypes such as proliferation and migration. Upstream mutations (e.g., KRAS mutations in non-small-cell lung (NSCLC)) can cause the pathway to become constitutively activated, driving tumor growth. AZD0364 is a potent, selective inhibitor of ERK's kinase activity against its cytosolic substrate p90RSK. It is currently in preclinical development, where it has shown dose-dependent, anti-tumor activity in xenograft models of KRAS-mutant NSCLC, including Calu-6 (where it shows regression) and A549. Treatment with AZD0364 demonstrates rapid and near-complete inhibition of phospho-p90RSK. In addition, prolonged inhibition with AZD0364 causes a gradual downregulation of p90RSK protein over time, without any corresponding change in p90RSK mRNA. Here we present a pharmacokinetic/pharmacodynamic (PK/PD) model that links AZD0364 concentration to inhibition of ERK activity through both a direct inhibition of phospho-p90RSK and an indirect down-regulation of total-p90RSK protein. Anti-proliferative and pro-apoptotic effects on efficacy are linked to changes in p90RSK. The model leads to two key implications (i) repeated dosing will cause apparent potency to improve over time, since the pool of available substrate (i.e., p90RSK) is itself being reduced and (ii) recovery of signaling to baseline will depend not on washout of the inhibitor but on protein synthesis rates. Protein half-lives appear quite different between tumor models of KRAS-mutant NSCLC, with A549 (~20h) significantly slower than Calu-6 (~4h). The model provides a conceptual framework on which to link the timescale of PD changes with those seen in efficacy. Taken together, this means that while a new PD steady-state is achieved in Calu-6 in a few days, it also recovers quickly, necessitating constant cover (daily dosing) to drive regression. On the other hand, while A549 is more robust to inhibition, and slower to reach steady-state inhibition (~2 weeks), it is also slower to recover, so that intermittent schedules can achieve efficacy similar to those achievable with daily dosing.

Citation Format: Francis D. Gibbons, Linda Sandin, Lyndsey Hanson, Rebecca Whiteley, Paul Farrington, Nicola Lindsay, Emma Davies, J Elizabeth Pease, Vikki Flemington. A PK/PD model quantitatively describes inhibition and down-regulation of p90RSK by ERK inhibitor AZD0364 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4913.
Abstract 4915: Preclinical pharmacology and toxicology of intravenous BPM31510, a coenzyme Q10-containing lipid nanodispersion
Authors: Linsenmayer David , Kazerounian Shiva , Thapa Khampaseuth , Spencer Carrie , Sarma Aishwarya , McCook John , Gesta Stephane , Vishnudas Vivek , Narain Niven R. , Sarangarajan Rangaprasad
Published: August 2018

Coenzyme Q10 (CoQ10) plays an important role in cellular metabolism with redox capabilities beyond the mitochondria. Although, the role of CoQ10 in providing benefit in diseases such as cardiovascular, neurodegeneration, and cancer is well established, it has been limited by the absence of delivery methods to achieve physiologically relevant bio-availability. BPM31510 is a CoQ10 (ubidecarenone) containing lipid nanodispersion that delivers supraphysiological concentrations of CoQ10 to tissues, cells and mitochondria. BPM31510 is currently in clinical trials for the treatment of solid tumors including pancreatic cancer and glioblastoma multiforme. This study describes the preclinical pharmacokinetic (PK) and toxicokinetic assessment of BPM31510 (62.5, 125, and 250 mg/kg) after acute (single) intravenous (IV) administration and chronic (3 times a week for 4 weeks), and after a two week recovery from the last exposure in rats. Here, it was demonstrated that the formulation enables an effective delivery of CoQ10 with a robust increase in plasma level and dose-dependent accumulation in several tissues. PK analysis of mean plasma concentration of CoQ10 after a single and repeat dose administration revealed a dose proportion effect on peak (Cmax) and total exposure (AUC0-t). Tissue analysis of CoQ10 levels demonstrates a dose-dependent increase in liver, lung and pancreas 72 hours post-last dose. A dose dependent elimination was observed in both male and females. No difference in pharmacokinetic of CoQ10 using this formulation was observed between males and females. Notably, chronic exposure to BPM31510 does not lead to toxicities as assessed by hematology and coagulation, clinical chemistry, histopathology and gross necropsy. These results indicate that the effective delivery and bioavailability of supraphysiological levels of CoQ10 after IV administration of BPM31510 is well tolerated.

Citation Format: David Linsenmayer, Shiva Kazerounian, Khampaseuth Thapa, Carrie Spencer, Aishwarya Sarma, John McCook, Stephane Gesta, Vivek Vishnudas, Niven R. Narain, Rangaprasad Sarangarajan. Preclinical pharmacology and toxicology of intravenous BPM31510, a coenzyme Q10-containing lipid nanodispersion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4915.
Abstract 492: Downregulation of microRNA-17-5p promotes EMT by targeting vimentin in colorectal cancer
Authors: Kim Tea Won , Lee Yeo Song , Hong Hye Kyung , Song Su Jeong , Yun Nak Hyeon , Cho Yong Beom
Published: August 2018

Background: Colorectal cancer (CRC) is one of the most frequent forms of cancer worldwide. Cells with abnormal growth have the ability to invade or spread to other parts of the body (metastasis). Metastasis is the most common cause of death in CRC patients and activation of epithelial-mesenchymal transition (EMT) triggers metastasis. Thus, it is important to understand the mechanisms of EMT to increase the survival rate of CRC. MicroRNA-17 (miRNA-17) has been proven to be significantly higher in CRC tissues than normal tissues. However, there are few papers about the role of miRNA-17 in CRC metastasis. Therefore, in this study, we evaluated the mechanism underlying miRNA-17-5p related EMT in colon cancer cells.

Methods: Expression level of miRNA-17-5p as well as target mRNA were analyzed in HCT-15, HT29, LoVo, SW480 and COLO205 cell lines. In order to evaluate the correlation between miRNA-17-5p and EMT phenomenon, selected cell lines were transiently transfected either miRNA-17-5p mimic or miRNA-17-5p inhibitor and then phenotyping studies were conducted. Moreover, to find out the direct target of miRNA-17-5p, we performed AGO2 immunoprecipitation in each colon cancer cell lines.

Results: Real-time PCR revealed that miRNA-17-5p expression reversely correlated with vimentin expression in five colon cancer cell lines. Overexpression of miRNA-17-5p inhibited vimentin expression, cell migration and cell invasion in both LoVo and HT29 cells. On the other hand, inhibition of miRNA-17-5p promoted vimentin expression, cell migration and cell invasion in the same parallel cell lines. Through AGO2 immunoprecipitation analysis, we observed that miRNA-17-5p directly bind to vimentin 3'UTR to influence its stability and expression at the transcriptional level.

Conclusion: Our data demonstrated that down-regulated miRNA-17-5p promotes colon cancer cell migration and invasion by regulating vimentin expression. These findings propose that miRNA-17-5p may serve as a potential prognostic biomarker in colorectal cancer.

Citation Format: Tea Won Kim, Yeo Song Lee, Hye Kyung Hong, Su Jeong Song, Nak Hyeon Yun, Yong Beom Cho. Downregulation of microRNA-17-5p promotes EMT by targeting vimentin in colorectal cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 492.
Abstract 494: Intravital discovery of miRNA drivers of human cancer cell directional invasion
Authors: Stoletov Konstantin V. , Willetts Lian , Jovel Juan , Woolner Emma , Lewis John D.
Published: August 2018

Metastatic cancer cells use directional ECM cues such as blood vessels or collagen fibers when invading through live tissue. Oncogenic miRNAs have been implicated as key regulators of cancer progression, yet the systemic discovery of miRNAs that drive directional cancer cell invasion has not been achieved. Here we describe the first in vivo quantitative whole human miRNAome screen for miRNA drivers of directional cancer cell invasion that is based on high-resolution intravital imaging. We identified several novel miRNAs that promote cancer cell invasion during the key rate-limiting step of cancer metastasis: the initiation of overt metastatic lesions. In vivo 4D cancer cell tracking revealed that these prometastatic miRNAs are required for successful invasion into collagen-rich tissue and for attachment to the outer surface of the vascular wall. Deregulation of these miRNAs led to formation of loose contacts with the vasculature and chaotic, nondirectional cancer cell invasion patterns in living tissue. Intravital SHG microscopy showed that inhibition of the expression of these miRNAs blocked the ability of cancer cells to rearrange the disorganized collagen network into collagen fiber bundles and stably protrude along these bundles. Further imaging analysis revealed that this miRNA expression specifically blocks vesicular transport of key cell invasion machinery proteins such as MT1-MMP to the cancer cell invadopodia. Human cancer gene expression database analysis showed that our top miRNA candidates are specifically deregulated in invasive pancreatic cancer. Indeed, intravital imaging analysis showed that blocking of metastatic miRNA function inhibited MT1-MMP secretion and ECM degradation by human pancreatic cancer cells. In summary, we identified a novel panel of human miRNAs that are functionally involved in the regulation of directional invasion and metastasis. This work establishes these miRNAs as promising therapeutic targets to block the metastatic spread of lethal cancers.

Citation Format: Konstantin V. Stoletov, Lian Willetts, Juan Jovel, Emma Woolner, John D. Lewis. Intravital discovery of miRNA drivers of human cancer cell directional invasion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 494.
Abstract 4948: MDM2 antagonism overcomes resistance to CDK4/6 inhibition in melanoma
Authors: Vilgelm Anna E. , Saleh Nabil , Riemenschneider Kelsie , Slesur Lauren , Chen Sheau-Chian , Ayers Gregory D. , Kauffman Rondi M. , Kelley Mark C. , Johnson Douglas B. , Richmond Ann
Published: August 2018

Metastatic melanoma is an aggressive disease characterized by resistance to conventional cancer treatments such as radiation and chemotherapy. While immune checkpoint blockade and BRAF inhibitor therapies are effective in many melanoma cases, a significant proportion of patients are resistant to these standard of care treatments and thus require new therapeutic approaches. We hypothesized that targeting CDK4/6 may offer hope to melanoma patients refractory to immunotherapy and BRAF inhibition, based on CDK4 being a key oncogene activated by mutations or deletions of CDKN2A gene, which are very common in melanoma (>50% of cases). However, in vivo studies using our extensive collection of melanoma patient-derived xenografts (PDX) showed that the majority of melanoma tumors are intrinsically resistant to CDK4/6 inhibition. We identified the mechanism of this resistance which was driven by cooperative activities of other CDKs expressed by tumor cells that compensated for the loss of CDK4/6 function to allow cell cycle progression through G1 and S phases. In order to overcome compensatory activation of other CDKs, we used small molecule antagonists of MDM2-p53 interaction, that stabilize p53 protein, which, in turn, upregulates an endogenous pan-CDK inhibitor, p21. Notably, combined MDM2 and CDK4/6 antagonism resulted in greater inhibition of tumor growth than either inhibitor individually. This synergistic effect was observed in multiple melanoma PDX models and in immunocompetent mice bearing mouse melanoma tumors. In summary, our preclinical data suggest that combining CDK4/6 inhibitors with MDM2 antagonists is a promising strategy for the treatment of metastatic melanoma, which should be further tested by a clinical study.

Citation Format: Anna E. Vilgelm, Nabil Saleh, Kelsie Riemenschneider, Lauren Slesur, Sheau-Chian Chen, Gregory D. Ayers, Rondi M. Kauffman, Mark C. Kelley, Douglas B. Johnson, Ann Richmond. MDM2 antagonism overcomes resistance to CDK4/6 inhibition in melanoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4948.
Abstract 495: Leptin facilitates ovarian cancer metastasis through miR-28-3p and matrix metalloproteinase-1 in the omental tumor microenvironment
Authors: Yeung Chi Lam Au , Co Ngai Na , Yeung Tsz-Lun , Mok Samuel C.
Published: August 2018

Advanced stage serous ovarian cancers spread beyond the pelvis and preferentially metastasize to the omentum, which is mainly composed of adipose tissue, suggesting that the omental microenvironment is a favorable niche for ovarian cancer cells. By comparing the transcriptome profiles of microdissected ovarian cancer tissues from the primary ovarian site and from the omental site, we identified matrix metalloproteinase-1 (MMP-1) as one of the most significant genes that was up-regulated in the omental site compared with that in the primary site. To identify mediators secreted by the omental microenvironment that up-regulated MMP-1 in the omental site tumors, transcriptome profiling was performed on microdissected ovarian tumor associated adipose tissue in the omental site and the ovarian stromal tissue in the primary ovarian tumor site. We identified leptin as one of the top differentially expressed genes in ovarian tumor associated adipose tissue in the omental site, suggesting that it might up-regulate MMP-1 in the omental ovarian cancer. To further delineate the role of MMP-1 in mediating the effect of leptin on ovarian cancer cell metastasis, ovarian cancer SKOV3 and OVCA433 cells were treated with leptin. The results showed that leptin increased MMP-1 mRNA and protein expression as assessed by quantitative RT-PCR and Western blot analyses, respectively. Furthermore, we demonstrated that leptin induced both the cell migration and invasion potential of SKOV3 and OVCA433 cells, and the effects were abrogated by transfecting cells with MMP-1 siRNAs. In addition, using Ion Torrent next generation sequencing, we found that miR-28-3p is down-regulated in leptin-treated SKOV3 and OVCA433 cells compared to the untreated cells, suggesting that it may play a role in mediating the effect of leptin on MMP-1 expression and the subsequent ovarian cancer cell motility and invasion potential. In conclusion, leptin secreted by the adipocytes in ovarian cancer associated omental microenvironment may be important in facilitating the ovarian cancer cell metastasis through the miR-28-3p/MMP-1 pathway.

Citation Format: Chi Lam Au Yeung, Ngai Na Co, Tsz-Lun Yeung, Samuel C. Mok. Leptin facilitates ovarian cancer metastasis through miR-28-3p and matrix metalloproteinase-1 in the omental tumor microenvironment [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 495.
Abstract 4951: Inhibiting guanylate binding protein 1 (GBP1) impedes ovarian cancer progression
Authors: Tailor Dhanir , Kumar Vineet , Pandrala Mallesh , Resendez Angel , Malhotra Sanjay V.
Published: August 2018

Ovarian cancer, the most common gynecologic malignancy, is a leading cause of cancer deaths in women. Seventy percent of patients at diagnosis present with stage III or IV disease, in which the tumor has disseminated beyond the ovaries and pelvic organs to distant sites. Despite resection and and chemotherapy, 80% of patients diagnosed with advanced epithelial ovarian cancer develop recurrent disease and overall prognosis is poor. Resistance to chemotherapeutic agents such as carboplatin and paclitaxel (taxane-based drugs) accounts for the lack of effectiveness of current therapy. Characterization of taxane-resistant tumors has shown that Class III β-tubulin (βTUB3) is significantly overexpressed in ovarian cancer as well as other cancers. Also, molecular characterization of the causes of treatment resistance revealed that βTUB3 plays a prominent role in the incorporation of guanylate binding protein 1, a conditionally expressed GTPase normally involved in the inflammatory response, as one of the critical effectors of taxane and radiotherapy resistance in ovarian cancer. Once in the cytoskeleton, GBP1 binds to pro-survival kinases such as serine/threonine-protein kinase pim-1 (PIM1) and initiates a signaling cascade that induces treatment resistance. We hypothesize that inhibiting the activity of GBP1 will restore sensitivity to taxane therapy. This is now well supported by our preliminary proof-of-concept studies. We have demonstrated that natural product-derived small molecule SU093 stabilizes GBP1 in a nonbinding conformation, resulting in the inhibition of GBP1:PIM1 interaction. The mechanistic studies using confocal microscopy showed that SU093 inhibits GBP1 by blocking its nuclear translocation and disrupts the tubulin dynamics. Cell cycle analysis showed that SU093 leads to G1 phase arrest followed by apoptotic cell death. SU093 treatment also induced pro-apoptotic protein Bax and reduced anti-apoptotic protein Bcl2. Overall, our in vitro and in vivo investigations provide a compelling foundation to develop a novel therapy to treat ovarian cancer by inhibition of GBP1.

Citation Format: Dhanir Tailor, Vineet Kumar, Mallesh Pandrala, Angel Resendez, Sanjay V. Malhotra. Inhibiting guanylate binding protein 1 (GBP1) impedes ovarian cancer progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4951.
Abstract 4954: Decoding tumor microenvironment to enhance NSCLC targeted therapy
Authors: Hu Haichuan , Sequist Lecia , Piotrowska Zosia , Kodack David , Hata Aaron , Niederst Matt , Benes Cyril , Engelman Jeffrey
Published: August 2018

Background: Tyrosine kinase inhibitors (TKI) have yielded promising responses in non-small-cell lung cancer (NSCLC) with EGFR mutations and ALK translocations. However, these and other targeted therapies are limited by intrinsic and acquired drug resistance. The previous study from our group investigated tumor autonomous resistance mechanisms by developing patient-derived cancer models (PDCs). In this study, we aimed to decipher the non-autonomous resistance mechanisms via tumor microenvironment by developing patient-derived fibroblast (PDF) models. Method: Cancer-associated fibroblast cell lines are established directly from individual EGFR mutant NSCLC biopsies. These cell lines, as representative of each patient's tumor microenvironment, are further subjected to functional analysis. An imaging-based high-throughput platform is developed to screen for non-autonomous resistance by co-culturing PDC and PDF models in vitro. In the parallel, two independent approaches are performed to further identify mechanisms underlying the non-autonomous resistance. These include a drug screen to determine the pathway maintaining the cancer cells' survival, and a secretomic analysis on the PDFs to identify the plausible cytokine(s) responsible for the resistance. Result: By co-culturing screening, non-autonomous resistance can be found in a wide spectrum of models. The subsequent drug screen reveals both a canonical HGF dependent and novel HGF independent mechanisms contributing to EGFR TKI resistance. Both of these can be explained by the PDF's variable cytokine secretion and can be overcome by specific therapeutic combinations. Moreover, the microenvironment-driven EGFR TKI resistance has also been validated in vivo. And the prevalence of the identified cytokine is further tested in clinical specimens. Conclusion: PDFs provide a new avenue to explore non-autonomous resistance for targeted therapy. Applying this approach, we identified both the canonical HGF dependent and novel HGF independent mechanisms that putatively conferring EGFR TKI resistance. Taking EGFR TKI therapy as a paradigm, these findings will be valuable to optimize targeted therapy and to inform the design of personalized pharmaceutical interventions.

Citation Format: Haichuan Hu, Lecia Sequist, Zosia Piotrowska, David Kodack, Aaron Hata, Matt Niederst, Cyril Benes, Jeffrey Engelman. Decoding tumor microenvironment to enhance NSCLC targeted therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4954.