bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 4783: Selective antitumor activity of NSC311152 toward medullary thyroid cancer by downregulating the transcription of RET oncogene
Authors: Sun Daekyu , Kumarasamy Vishnu Muthuraj , Alqahtani Tariq
Published: August 2018

The RET (REarranged during Transfection) proto-oncogene encodes a tyrosine-kinase receptor specifically expressed in tissues originated from neuroectodermal tissues. Dominant-activating mutations in this RET proto-oncogene is often associated with Multiple Endocrine Neoplasia type 2A and 2B and Familial Medullary Thyroid Carcinoma syndromes, characterized by the occurrence of medullary thyroid carcinomas. Human medullary thyroid carcinoma cell line TT cell line harbours a MEN2A-type mutation, so this cell line could be a useful cell system to investigate the antitumor activity of new agents interfering with the function of RET oncogene in medually thyroid cancer. Recently, ellipticine and its derivatives were identified as excellent RET G-quadruplex stabilizing agents. Furthermore, these compounds also interfered with the transcriptional mechanism of the RET gene in TT cells, subsequently decreasing the endogenous RET protein expression. In present study, we demonstrated the specificity of NSC311152 by using papillary thyroid carcinoma (PTC) cells, the K1, which carry BRAF and PIK3CA mutations but lacks the dominant-activating mutations in this RET proto-oncogene. NSC311152 selectively suppresses cell proliferation by inhibiting the intracellular Raf/MEK/ERK and PI3K/Akt/mTOR signaling pathways in the TT cells. The systemic administration of NSC311152 in a mouse MTC xenograft model significantly inhibited the tumor growth through RET downregulation, whereas NSC31152 only showed a moderate antitumor activity against K1 xenograft tumors.

Citation Format: Daekyu Sun, Vishnu Muthuraj Kumarasamy, Tariq Alqahtani. Selective antitumor activity of NSC311152 toward medullary thyroid cancer by downregulating the transcription of RET oncogene [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 4783.
Abstract 479: miR-372 enhances tumorigenesis and drug resistance in oral carcinoma by targeting ZBTB7A transcription factor
Authors: Yeh Li-Yin , Chou Chung-Hsien , Liu Chung-Ji , Lin Shu-Chun , Chang Kuo-Wei
Published: August 2018

miRNA-mediated post-transcriptional regulation of targeted genes plays crucial roles in neoplastic process. miR-372 has been shown an oncogenic miRNA which is hypoxia-inducible and is conspicuously up-regulated in oral squamous cell carcinoma (OSCC). Zinc finger and BTB domain containing 7A (ZBTB7A) is a transcriptional repressor modulating a great diversities of physiological or oncogenic regulation. This study identified that ZBTB7A was a direct target of miR-372. ZBTB7A was down-regulated in 75% of OSCC tumors relative to adjacent oral mucosa. Reverse correlation across miR-372 expression and ZBTB7A expression was found in tumor samples. In OSCC cells with the stable knockdown of ZBTB7A, the oncogenic potential and drug resistance increased. Whereas, such increase was attenuated by ZBTB7A expression. High throughput screening and validation assay confirmed that ZBTB7A was able to repress multiple oncogenic factors and activate the expression of Trail-R1, Trail-R2 and Fas to increase the drug sensitivity in OSCC cells. miR-372 induction drastically repressed the expression of apoptosis genes by inhibiting ZBTB7A. This was accompany with the enrichment of oncogenicity and the increased tolerance to the toxicity of cisplatin and taxol. This study signifies the importance of miR-372-ZBTB7A-downstream effectors in mediating pathogenesis and drug resistance of OSCC. Interception of this pathogenic cascade would confer therapeutic benefits against oral carcinoma.

Citation Format: Li-Yin Yeh, Chung-Hsien Chou, Chung-Ji Liu, Shu-Chun Lin, Kuo-Wei Chang. miR-372 enhances tumorigenesis and drug resistance in oral carcinoma by targeting ZBTB7A transcription factor [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 479.
Abstract 4790: YH25448, an irreversible 3rd generation EGFR TKI, exhibits superior anticancer effects with potent brain BBB penetration in NSCLC
Authors: Yun Jiyeon , Hong Min Hee , Kim Seok-Young , Park Chae Won , Kim So-Young , Yun Mi Ran , Kang Han Na , Pyo Kyoung-Ho , Koh Jong Sung , Song Ho-Juhn , Lee Young- Sung , Oh Se-Woong , Choi Soongyu , Cho Byoung-Chul
Published: August 2018

EGFR mutated lung cancer shows approximately 10-15% of non-small cell lung cancer (NSCLC). Although the best therapeutic EGFR tyrosine kinase inhibitors (TKIs) targeting mutant EGFR, such as gefitinib and erlotinib, are used in the first line treatment of patients with advanced EGFR mutated NSCLC, the acquired resistance to the drugs usually appears in 10-12 months of therapy by the occurrence of a second EGFR mutation T790M. YH25448, a highly mutant-selective and irreversible 3rd generation EGFR TKI potently penetrating blood-brain barrier (BBB) penetration, targets both activating EGFR mutations Del19, L858R and T790M mutation while sparing wild type. In NSCLC cell lines and primary cancer cells from patients harboring EGFR mutations, YH25448 showed more potent inhibition of cancer cell growth and significantly increased tumor cell apoptosis compared to osimertinibs, which is one of 3rd generation EGFR TKIs. In vivo mouse model implanted with H1975 cells, YH25448 treatment at the once-daily showed a dramatic dose-dependent tumor regression in both subcutaneous and intracranial lesions with no abnormal signs such as skin keratosis shown in osimertinib-treated mice. Plasma half life of YH25448 was 5.9-6.8 hr and tumor to plasma AUC0-last ratio was 3.0-5.1 in tumor bearing mice. YH25448 also showed excellent penetration of the BBB, achieving CSF concentrations exceeding the IC50 value for pEGFR inhibition in the tumor-bearing mice. Taken together, these findings suggest important role for the further development of YH25448 as a novel therapeutic for the treatment of EGFR mutant-positive NSCLC patients with brain metastases.

Citation Format: Jiyeon Yun, Min Hee Hong, Seok-Young Kim, Chae Won Park, So-Young Kim, Mi Ran Yun, Han Na Kang, Kyoung-Ho Pyo, Jong Sung Koh, Ho-Juhn Song, Young- Sung Lee, Se-Woong Oh, Soongyu Choi, Byoung-Chul Cho. YH25448, an irreversible 3rd generation EGFR TKI, exhibits superior anticancer effects with potent brain BBB penetration in NSCLC [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 4790.
Abstract 4791: OMO-1, a potent, highly selective, orally bioavailable, MET kinase inhibitor with a favorable preclinical toxicity profile, shows both monotherapy activity, against MET pathway-driven tumors, and EGFR TKI combination activity in acquired resistance models
Authors: Libouban Marion , Jovcehva Eleonora , Lange Desiree De , Janssens Boudewijn , Verhulst Tinne , Ogata Souichi , Wroblowski Berthold , Mevellec Laurence , Lu Tianbao , Clack Glen , Perera Timothy
Published: August 2018

Activation of the MET/HGF pathway has been linked to tumor initiation, metastasis, angiogenesis and resistance to therapeutic agents. Here we present pharmacological characterization of OMO-1 (formerly JNJ-38877618), a potent, highly selective, orally bioavailable MET kinase inhibitor with nM binding affinity (Kd=1.4 nM) and enzyme inhibitory activity against wt and M1268T mutant MET (2 and 3 nM IC50). MET inhibitory effects were assessed in proliferation, colony formation and motility assays. OMO-1 displayed nM potency against MET Ampl/mutant and therapy resistant models. In vivo, OMO-1 induced complete inhibition of tumor growth in 3 models: the SNU5 MET amp gastric, U87-MG HGF autocrine glioblastoma and Hs746T MET exon 14 skipping mutant gastric cancer. OMO-1 induced regression of large MET amplified EBC-1 SqNSCLC where OMO-1 led to dose- and time-dependent inhibition of MET kinase activation, with the duration of target shut down considerably exceeding plasma exposure times. Combination treatments were well tolerated and improved EGFR targeted therapy. Although single agent OMO-1 had no effect on NSCLC HCC827 EGFR, combination with Erlotinib led to delayed onset of tumor recurrence. The acquired EGFR inhibitor resistant model HCC827-ER1 was determined to be MET amplified. OMO-1 and erlotinib both inhibited tumor growth of this model whilst combination induced tumor regression. In an EGFR inhibitor resistant PDX having MET amplification, single agent OMO-1 caused tumour stasis whereas MetMab/erlotinib only led to tumor growth delay. The potent preclinical activity we have observed, supports ongoing clinical development of OMO-1 in patients with MET pathway-driven tumors.

Citation Format: Marion Libouban, Eleonora Jovcehva, Desiree De Lange, Boudewijn Janssens, Tinne Verhulst, Souichi Ogata, Berthold Wroblowski, Laurence Mevellec, Tianbao Lu, Glen Clack, Timothy Perera. OMO-1, a potent, highly selective, orally bioavailable, MET kinase inhibitor with a favorable preclinical toxicity profile, shows both monotherapy activity, against MET pathway-driven tumors, and EGFR TKI combination activity in acquired resistance models [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 4791.
Abstract 4797: In vitro and in vivo effect of ARQ 531 on Trk family kinases
Authors: Yu Yi , Schwartz Gabi , Schamber Pascal , Savage Ron E. , Eathiraj Sudharshan , Hall Terence , Schwartz Brian
Published: August 2018

The tropomycin kinase (Trk) receptor family contain Trk A, B and C that are encoded by the NTRK1, NTRK2, and NTRK3 genes respectively. Trk family kinases have been shown to play a very important role in the development and physiological functions of the nervous system. Recently, chimeric Trk kinases resulted from gene fusions of NTRK genes are involved in initiation and progression of various cancers such as sarcoma, thyroid, salivary gland cancers, etc. Targeting such alteration of Trk family kinases becomes a new avenue for the therapeutic intervention. ARQ 531 has biochemical IC50 values of 1.3 nM, 1.8 nM and 1.8 nM for Trk A, B and C, respectively with targeting a unique set of other kinases. In a cell based assay, ARQ 531 inhibits kinase activity of Trk A, B and C in UOS2 cells overexpressing Trk family kinases with IC50 values of 50.5 nM, 28.0 nM and 4.1 nM respectively. Pathway analysis shows that ARQ 531 abolished autophosphorylation of TMP3-Trk A in colon cancer KM-12 cells after 2-hour treatment, concomitant with marked inhibition of pAKT, pERK and pPLCγ1. Moreover, in Trk A-overexpressing K562 cells, ARQ 531 suppressed phosphorylation of Trk A and its downstream targets AKT and MAPK. Anti-proliferative activity of ARQ 531 has been demonstrated in Ba/F3 system over-expressing fusion Tel-Trk family kinases (ETV6-NTRK1, 2 or 3), exhibiting IC50 value of 300, 481, and 341 nM for Tel-Trk A, B or C respectively. In TMP3-TrkA(TMP3-NTRK1) fusion-driven KM12 cells driven by ARQ 531 strongly suppressed cell proliferation with an IC50 value of 130 nM. Subsequently, apoptotic response was observed in KM-12 cells after treatment of ARQ 531 for 24 hours, which was demonstrated by the increase in cleaved PARP1 and cleaved caspase 3. Significant anti-tumor activity of ARQ 531 was observed in KM-12 xenograft mouse model. In conclusion, ARQ 531 is a potent Trk family kinase inhibitor and the results from preclinical study provides rationale for testing ARQ 531 in a clinical setting, particularly in cancers driven by Trk fusion kinases.

Citation Format: Yi Yu, Gabi Schwartz, Pascal Schamber, Ron E. Savage, Sudharshan Eathiraj, Terence Hall, Brian Schwartz. In vitro and in vivo effect of ARQ 531 on Trk family kinases [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 4797.
Abstract 4799: Nef-M1 peptide inhibits CXCR4 driven Wnt/β-catenin signaling in breast cancer
Authors: Katkoori Venkat R. , Manne Upender , Bumpers Harvey L.
Published: August 2018

Introduction: The Nef-M1 peptide (Nef-M1) competes effectively with the natural ligand of CXCR4, SDF-1α, and exhibits anti-tumorigenic activity in breast cancer (BC). However, the molecular mechanisms of action of Nef-M1 on BC remain unclear. In this study, we evaluated the Nef-M1 inhibition of CXCR4 driven Wnt/β-catenin pathway in BC. Experimental Design: Cell line derived xenografts (CDX), patient derived explant (PDE) and in vitro cell based models were used to examine the mechanisms of action of Nef-M1. The severe combined immunodeficient mice with tumor were treated intraperitoneally either with Nef-M1 or sNef-M1 (control). Preparation of BC tissue, explant complete media, and cultures and treatment for 48 hours was performed for the PDE study. Sections from tumors were evaluated by immunostaining (IHC) for signaling proteins implicating BC progression. Western blot (WB) analyses were also performed on lysates of both cell lines and tumors to assess the effect of Nef-M1 on the Wnt/β-catenin, stem cell or mitogen-activated protein kinase (MAPK) pathways. Results: The present study revealed that PDE recapitulate multiple biological features of the disease and these were found to be very similar to the corresponding original tumors. IHC analysis for Ub-H2B, a stem cell signaling protein that correlates with advanced disease and metastasis indicated that Nef-M1 treated CDX or PDE tumors had low expression of Ub-H2B. However, sNef-M1 treated tumors had high expression of Ub-H2B. WB analyses indicated that Nef-M1 not only suppressed the expression of Ub-H2B, but also significantly suppressed the activation of MAPK (e.g. p38, ERK) and Akt proteins in BC. Nef-M1 treated BC displayed inhibition of Wnt/β-catenin signaling as demonstrated by an increased expression of p21 and decreased expression of beta-catenin, cyclin D1, Axin 2 and survivin. Cells expressing CXCR4 became susceptible to Nef-M1-induced inhibition of MAPK, Akt, Wnt/beta-catenin and stem cell signaling pathways. Conclusions: These results indicate that Nef-M1 suppresses CXCR4 mediated activation of Wnt/β-catenin and MAPK pathways. Therefore, Nef-M1 inhibition of these signaling pathways may be a promising therapeutic strategy for BC. This work was supported by NIH/NCI Workforce Diversity Grant R21-CA171251.

Citation Format: Venkat R. Katkoori, Upender Manne, Harvey L. Bumpers. Nef-M1 peptide inhibits CXCR4 driven Wnt/β-catenin signaling in 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 4799.
Abstract 4800: Targeting the polyamine pathway as a novel therapeutic treatment against diffuse intrinsic pontine glioma
Authors: Khan Aaminah , Tsoli Maria , Yu Denise , Joshi Swapna , Gamble Laura , Franshaw Laura , Haber Michelle , Ziegler David S.
Published: August 2018

Diffuse intrinsic pontine glioma (DIPG) is a highly aggressive paediatric brainstem tumour, with a peak incidence in middle childhood and a median survival of less than 1 year in the majority of cases. The dismal prognosis associated with DIPG is exacerbated by the repeated failure of over 250 clinical trials to improve survival over standard radiotherapy. Therefore novel and innovative therapeutic approaches are urgently needed to needed to treat this devastating disease. Polyamines are small intracellular polycations that control key aspects of cell biology, such as cell replication/growth, differentiation and survival and can be found up-regulated in many cancers. Difluoromethylornithine (DFMO) is an FDA-approved inhibitor of the enzyme ornithine decarboxylase (ODC1) which is involved in polyamine synthesis. The aim of this study was to investigate the efficacy of polyamine pathway inhibitors such as DFMO as a therapeutic strategy against DIPG. By RT-qPCR and western blotting, we observed high expression levels of key players of the polyamine pathway in a panel of DIPG samples. Through alamar blue cytotoxicity assays and soft-agar clonogenic assays, DFMO was found to be effective against a panel of neurosphere-forming DIPG cells. The activity of DFMO was synergistically enhanced when combined with a polyamine transport inhibitor, AMXT-1501. Increased apoptotic activity following either DFMO or AMXT-1501 treatment, alone or in combination, was observed by western blotting and flow cytometric analysis of Annexin V/7AAD stained cells. In addition, reduced uptake of the radiolabelled polyamine, spermidine, in the presence of AMXT-1501 confirmed polyamine transport inhibition in DIPG cells. Consistent with the in vitro results, the combination of DFMO and AMXT-1501 significantly prolonged the survival of mice bearing DIPG orthografts, and the combination therapy represents the most effective combination treatment we have tested to date in our DIPG animal model. Our results suggest that the polyamine pathway is a potential therapeutic target for this highly aggressive paediatric brain tumour while a number of clinical trials based on this approach are currently underway in a variety of malignancies.

Citation Format: Aaminah Khan, Maria Tsoli, Denise Yu, Swapna Joshi, Laura Gamble, Laura Franshaw, Michelle Haber, David S. Ziegler. Targeting the polyamine pathway as a novel therapeutic treatment against diffuse intrinsic pontine glioma [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 4800.
Abstract 4810: Targeting androgen receptor in combination with cisplatin: Effective treatment strategy for muscle invasive bladder cancer
Authors: Tyagi Ashish , Chandersekaran Balaji , Rai Samarpit , Alatassi Houda , Haddad Ahmed Q. , Ankem Murali K. , Damodaran Chendil
Published: August 2018

Background: Bladder cancer is one of the major causes of cancer death in US and worldwide. Cisplatin is a key component of chemotherapeutic regimens employed in the treatment of advanced bladder cancer. The role of androgen and androgen receptor (AR) signaling in bladder cancer remains uncharacterized.

Aim: The aim of the study is to delineate the role of AR in bladder cancer and to determine whether combination of AR inhibitor, enzalutamide (Enz) and cisplatin-based therapies effectively inhibit the growth of muscle invasive bladder cancer (MIBC).

Methods: AR expression was determined in 75 human bladder cancer specimens and in a panel of bladder cancer cell lines. Cells grown in charcoal stripped media supplemented with dihydrotestosterone (DHT) were treated with cisplatin, enzalutamide (AR inhibitor), or a combination of both. Cellular/phenotypic analysis including MTT assay, apoptotic assay, migration as well as invasion assays and molecular analysis including western blotting, real time PCR analysis were performed. Isobologram analysis for the combination was performed and analyzed with CompuSyn. Experiments were repeated in triplicates and analyzed with unpaired Student's t-test and one way ANOVA *p≤0.05, **p≤0.01, ***p≤0.001.

Results: AR expression was seen in around 40% of bladder cancer patients. Inhibition of AR signaling by enzalutamide effectively inhibited the growth of AR+ MIBC cells. Interestingly, enzalutamide in combination with cisplatin (Enz + Cis) synergistically inhibited the proliferation of MIBC cells, TCCSUP (CI: 0.42, 1.25 + 5 μM) and J82 (CI: 0.79, 2.5 + 5 μM) at low concentrations of enzalutamide and cisplatin resp.. The molecular studies revealed the induction of DNA damage markers (pATM, pATR, pChk1, pHis) and enhanced expression of the pro-apoptotic genes (Bax, caspases-3 and PARP) in Enz+Cis treated AR+ MIBC cells. In addition, we demonstrated abrogation of invasive and migratory potential with Enz+Cis treatment, by downregulation of the mesenchymal markers (N-cadherin, slug, β-catenin, and vimentin) in both cell lines. Our studies suggest combination of Enz + Cis may be effective in patients with AR+ MIBC.

Conclusion: Combination of cisplatin and AR inhibition effectively inhibit bladder tumor growth and migration, and hold promise as synergetic therapies for AR+ bladder cancer patients.

Citation Format: Ashish Tyagi, Balaji Chandersekaran, Samarpit Rai, Houda Alatassi, Ahmed Q. Haddad, Murali K. Ankem, Chendil Damodaran. Targeting androgen receptor in combination with cisplatin: Effective treatment strategy for muscle invasive bladder 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 4810.
Abstract 4811: Inhibition of PLK1 abrogates side population and increases radiation-induced DNA damage in human glioblastoma
Authors: Pandey Arvind , Mai Junhua , Tripathi Satyendra C. , Hanash Samir M. , Shen Haifa , Mitra Sankar
Published: August 2018

Glioblastoma multiforme (GBM), a highly malignant form of brain tumor has limited treatment modalities with poor patient survival. Expression of CD133, a marker of cancer stem cells (CSCs), has been linked to GBM recurrence, metastasis and radiation/drug resistance. The GBM CSCs exhibit high level of ABC transporters, DNA repair enzymes and anti-apoptotic proteins. The side population (SP) phenotype of CSCs with high levels of ABC transporters is associated with chemo-resistance. Overexpression of Polo-like kinase-1 (PLK1), a key cell cycle regulator, has been linked to poor prognosis of various cancers. However, the role of PLK1 in radio/chemo-resistance of GBM is poorly understood. In this study, we explored the use of PLK1 inhibitor Volasertib in combination with temozolomide (TMZ) followed by radiation to overcome resistance in GBM, both in vitro and in vivo.

Our results revealed that Volasertib and TMZ act synergistically at a sub-lethal dose to inhibit cell proliferation and induce apoptosis. Both Volasertib and TMZ strongly induce reactive oxygen species (ROS) which may cause cell death by reducing repair capacity. Combined treatment with TMZ and Volasertib followed by radiation showed persistent DNA damage after removal of drugs for 24 hrs. In contrast to earlier reports, significant decrease in the side population was also observed, even after radiation treatment.

We also observed that Volasertib alone or in combination with TMZ activated STAT1 pathways and inhibited MAPK/AKT activation. As the latter pathway promotes apoptosis, our results suggest higher tumor growth inhibitory effect of combinatorial treatment compared to single agents in xenograft mouse model.

In summary, while Volasertib can be used alone or in the combination with radiation, Volasertib combined with TMZ may be useful to inhibit recurrence of GBM after radiation therapy. Furthermore, increased STAT1 expression may modulate the tumor-microenvironment and improve immunotherapy by MHC class 1 upregulation.

Citation Format: Arvind Pandey, Junhua Mai, Satyendra C. Tripathi, Samir M. Hanash, Haifa Shen, Sankar Mitra. Inhibition of PLK1 abrogates side population and increases radiation-induced DNA damage in human glioblastoma [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 4811.
Abstract 4819: High-throughput screening of glioma stem-like cells (GSCs) identifies synergistic therapeutic combination of FGFR inhibitor and CDK4/6 inhibitor
Authors: Dong Jianwen , Martinez-Ledesma Emmanuel , Nguyen Nghi , Wu Shaofang , Piao Yuji , Tiao Ningyi , Park Soon Young , Brunell David , Stephan Clifford , Verhaak Roel , Sulman Erik , Balasubramaniyan Veerakumar , Groot John F. de
Published: August 2018

High-grade gliomas are challenging tumors to treat. The lack of efficacy of single-agent therapy emphasizes the importance of developing combination strategies to overcome acquired resistance. Quantitative high-throughput screening (HTS) of 2 and 3 drug combinations at 5 concentrations (maximal concentration of 1 uM) of each agent were evaluated in a panel of GSCs to identify potentially novel combination therapy. Genomic, proteiomic (reverse protein lysate array, RPPA) and GSC subtype were correlated with drug IC50 to find biomarkers of drug sensitivity. GSCs were classified as sensitive (IC50 ≤ 1µM) or resistant (IC50 >1µM) for single-agent screening. The Bliss independence model and combination index (CI) criteria were used to quantify the synergy of compound combinations. Evaluation of drug combination data for synergistic combination identified FGFR inhibitor LY2874455 and CDK4/6 inhibitor LY2835219 as the most effective combinations for multiple drug sets. Abnormal activation of FGFR and alterations in the CDKN2A-CDK4/6-Retinoblastoma 1 (RB1) pathway have been implicated in glioblastoma pathogenesis. We further investigated the in vitro combination efficacy of FGFR inhibitor and CDK4/6 inhibitor. Compared to single agent, combination of FGFR inhibitor and CDK4/6 inhibitor induced prominent cleaved poly ADP ribose polymerase (c-PARP), an index of apoptosis, which was further confirmed by Annexin V staining. Combination therapy significantly inhibited p-RB, p-STAT3, p-Akt, p-Erk and p-c-Jun expression compared to single agent. Genomic data demonstrated that high PDGFRα expression and low methylation correlated to sensitivity to the FGFR and CDK4/6 inhibitor combination. These findings were validated by demonstrating that this synergistic sensitivity was decreased by knocking out PDGFRα by CRISP/Cas9 system with the combination index (CI) at IC50 increased from 0.964 to 2.247. In addition, Western blotting showed that expression of PDGFRα and Notch1 was significantly inhibited by combination treatment. However, this combination failed to show any survival and tumor inhibition benefits in intracranial xenograft mouse models.

Citation Format: Jianwen Dong, Emmanuel Martinez-Ledesma, Nghi Nguyen, Shaofang Wu, Yuji Piao, Ningyi Tiao, Soon Young Park, David Brunell, Clifford Stephan, Roel Verhaak, Erik Sulman, Veerakumar Balasubramaniyan, John F. de Groot. High-throughput screening of glioma stem-like cells (GSCs) identifies synergistic therapeutic combination of FGFR inhibitor and CDK4/6 inhibitor [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 4819.
Abstract 4824: Rac1b overexpression confers resistance to chemotherapy treatment in colorectal cancer
Authors: Chaturvedi Pallavi , Goka Erik , Garza Adriana De La , Lopez Dayrelis Mesa , Lippman Marc E.
Published: August 2018

Acquired resistance to chemotherapy represents a major limitation in the treatment of colorectal cancer. New strategies to circumvent this problem are critical to prolonging patient survival. Previous studies have shown that Rac1b, a constitutively activate isoform of the small GTPase Rac1, is upregulated with disease progression and promotes cell proliferation and inhibits apoptosis by activation of NFκB signaling. In the present study, we show that Rac1b overexpression correlates with colorectal cancer stage with the highest levels identified in metastatic cancer. We show that Rac1b expression is associated with increased growth of colon adenocarcinoma cells and that modulation of Rac1b expression in colon adenocarcinoma cells reduces NFκB activity. The use of a Rac inhibitor in colon cancer cells reduces the 2D and 3D colony formation of colon adenocarcinoma cells, reduces the migratory capacity of these cells, and suppresses NFκB signaling. Rac inhibition also reduces tumor growth in a xenograft model of colon adenocarcinoma cells. Surprisingly, Rac1b expression and NFκB activity was upregulated in colon carcinoma cells treated with 5-FU and oxaliplatin (two components of the standard of care FOLFOX chemotherapy regimen), suggesting that Rac1b facilitates chemo-resistance by activation of NFκB signaling. Knock down of Rac1b in colon cancer cells or Rac inhibitor increases the sensitivity of the cells to oxaliplatin. When used in combination, inhibition of Rac in the colon cancer cells prevents the increase in NFκB activity associated with chemotherapy treatment and increases the sensitivity of the cells to oxaliplatin. Moreover, while Rac inhibition or oxaliplatin treatment alone reduces the growth of colorectal cancer in vivo, combination therapy results in significant further reduction of tumor growth than either single agent alone. Thus, we provide the first evidence that Rac1b expression confers resistance to standard of care chemotherapy in colorectal cancer. Additionally, we show that the use of a Rac inhibitor prevents chemoresistance by blocking activation of chemotherapy induced NFκB signaling providing a novel strategy to overcome resistance to chemotherapy in colorectal cancer.

Citation Format: Pallavi Chaturvedi, Erik Goka, Adriana De La Garza, Dayrelis Mesa Lopez, Marc E. Lippman. Rac1b overexpression confers resistance to chemotherapy treatment 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 4824.
Abstract 4827: Magnetic iron oxide nanoparticles induce apoptosis and autophagic cell death in prostate cancer cells treated with docetaxel via ROS generation and NF-KB signaling
Authors: Kojima Kanako , Takahashi Sanai , Saito Shungo , Nittami Tadashi , Usugi Eri , Ishii Kenichiro , HIrokawa Yoshifumi , Watanabe Masatoshi
Published: August 2018

Patients with metastatic castration-resistant prostate cancer (mCRPC) have a poor prognosis. Docetaxel (DTX)-based therapy is one of current standard treatments for mCRPC since 2004 although cabazitaxel, abiraterone acetate, and enzalutamide are three agents recently approved for the treatment of mCRPC. Although DTX-based chemotherapy has been shown to improve the quality of life in patients with the advanced disease, this needs to be improved because of limitations by lack of specificity, toxicity, and progression of docetaxel-resistance. Thus, combination of docetaxel with other compounds or drugs is needed to overcome these problems. We have investigated usefulness of magnetic iron oxide nanoparticles (MNPs- Fe3O4) for cancer diagnosis and therapy, showing that MNPs- Fe3O4 may modify the effect of chemotherapy in prostate cancer cells in vitro. The purpose of this study was to analyze the combined effect of docetaxel and MNPs- Fe3O4 on prostate cancer cell lines, DU145 and PC-3 and clarify their mechanisms. Electron microscopy, flow cytometry and Western blotting were used to study apoptosis and autophagic cell death with/without an autophagic inhibitor. Our results showed that MNPs- Fe3O4 produced reactive oxygen species (ROS) and 8-OHdG, and the combination of docetaxel and MNPs- Fe3O4 inhibited cancer cell growth and induced apoptosis and autophagic cell death. Although docetaxel induced nuclear factor-kappaB (NF-KB) expression, combination of docetaxel and MNPs inhibited NF-KB expression. These results suggest that MNPs- Fe3O4 may enhance effect of docetaxel on prostate cancer cells via ROS generation and inhibition of NF-KB signaling, leading to new tumor ablation therapies.

Citation Format: Kanako Kojima, Sanai Takahashi, Shungo Saito, Tadashi Nittami, Eri Usugi, Kenichiro Ishii, Yoshifumi HIrokawa, Masatoshi Watanabe. Magnetic iron oxide nanoparticles induce apoptosis and autophagic cell death in prostate cancer cells treated with docetaxel via ROS generation and NF-KB signaling [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 4827.
Abstract 4830: Selective DNA-PK inhibitor, M3814, boosts p53 apoptotic response to DNA double strand breaks and effectively kills acute leukemia cells: Implications for AML therapy
Authors: Haines Eric , Zimmermann Astrid , Zenke Frank , Blaukat Andree , Vassilev Lyubomir T.
Published: August 2018

M3814 is a selective inhibitor of DNA-PK in clinical development. It effectively blocks non-homologous end joining repair of DNA double strand breaks (DSB) and strongly potentiates the antitumor effect of ionizing radiation (IR) and topoisomerase II inhibitors. By inhibiting DNA-PK catalytic activity in the presence of DSB damage, M3814 disrupts a previously unrecognized negative regulatory loop between DNA-PK and ATM, leading to increased activation of the ATM pathway, including its downstream targets, CHK2 and p53. As a result, in cancer cells expressing wild-type p53, DNA-PK inhibitor strongly activates the p53 response to DSB DNA damage and its two main functions- cell cycle arrest and apoptosis. While p53 activation in p53 wild-type epithelial cancer cells causes effective cell cycle arrest, the majority of the epithelial tumors lose their ability to undergo p53 dependent apoptosis. In contrast, tumor cells from patients with acute leukemia express wild-type p53 in with preserved p53 apoptotic function, making them amenable to p53 activation approaches. Here, we investigate the therapeutic potential of M3814 in combination with DSB-inducing agents in acute leukemia cells. M3814 strongly potentiated the activity of IR in three p53 wild-type leukemia cell lines (MOLM-13, MOLT-4, MV4-11) but had minimal effect on the p53-null HL-60 and THP-1 lines. This potentiation was due to enhanced activation of the p53 pathway as demonstrated by substantially increased expression of p53 transcriptional targets, p21 and PUMA, and induction of apoptosis only in p53 wild-type cells. M3814 showed synergism in p53-dependent cell killing with the topoisomerase inhibitors, daunorubicin and idarubicin, and 2-3 fold increase in the potency of daunorubicin/cytarabine combination in p53 wild-type acute myeloid leukemia (AML) cells. Daunorubicin/cytarabine/M3814 combinations were better tolerated by CD34+ bone marrow cells harvested from healthy volunteers and tested in vitro. These results support further exploration of M3814 as a novel combination partner in the treatment of p53 wild-type AML.

Citation Format: Eric Haines, Astrid Zimmermann, Frank Zenke, Andree Blaukat, Lyubomir T. Vassilev. Selective DNA-PK inhibitor, M3814, boosts p53 apoptotic response to DNA double strand breaks and effectively kills acute leukemia cells: Implications for AML 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 4830.
Abstract 4847: Evaluation of the combination of olaparib and cediranib in small-cell lung cancer cells
Authors: Morikawa Naoto , Nilsson Monique B. , Guijarro Irene , Fan You-Hong , Poteete Alissa , Heymach John V.
Published: August 2018

Metastatic Small cell lung cancer (SCLC) is exceptionally lethal, having a median survival of 9-10 months from the time of diagnosis and a 5 year survival rate of less than 2 percent. More effective treatment approaches to SCLC are desperately needed. Poly ADP-ribose polymerase (PARP) inhibitor such as olaparib exploit the concept of synthetic lethality by selectively targeting cancer cells with defective DNA repair pathways. Preclinical data indicates that SCLC cell lines overexpress PARP and are sensitive to PARP inhibition, and PARP inhibitors show promise in the clinical setting of SCLC. The identification of combination regimens that potentiate the efficacy of PARP inhibition would be of great clinical value. Recent findings indicate that olaparib and the vascular endothelial growth factor receptor (VEGFR) inhibitor, cediranib, is an effective therapeutic combination in patients with BRCA wild-type ovarian cancer. Therefore, we evaluated the efficacy of the olaparib and cediranib combinations in SCLC models. Human SCLC cell lines, NCI-H841, H526, COR-L24 and murine SCLC cell line TKOmTmG were sensitive to olaparib or cediranib therapy in vitro as determined by Cell Titer Glo® assay. Moreover, a significantly greater effect on cell viability was observed when olaparib and cediranib were used in combination. Likewise, in H841 xenograft models, single agent treatment of olaparib or cediranib inhibited tumor growth, and combination treatment of olaparib plus cediranib induced tumor regression. Western blot analysis indicated that treatment with cediranib or the combination of olaparib and cediranib induced PD-L1 protein expression both in vivo and in vitro. In TKOmTmG xenograft model in syngeneic mice, programmed death-ligand 1 (PD-L1) inhibitor plus olaparib or olaparib/cediranib combination resulted in superior combined efficacy compared to the respective single agent therapies in terms of tumor growth inhibition. These data indicate that olaparib plus cediranib may be an effective therapeutic strategy for the treatment of SCLC. Further study is warranted to understand the mechanism of action and clinical activity.

Citation Format: Naoto Morikawa, Monique B. Nilsson, Irene Guijarro, You-Hong Fan, Alissa Poteete, John V. Heymach. Evaluation of the combination of olaparib and cediranib in small-cell lung cancer cells [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 4847.
Abstract 4852: Induction of HRD by targeting G9a and MTDH in DNA repair proficient endometrial cancer cells
Authors: Meng Xiangbing , Yang Shujie , Bi Jianling , Li Yiyang , Zhang Yuping , Areecheewaku Sudartip , Li Mary , Wang Zihan , Salem Aliasger K. , Leslie Kimberly K.
Published: August 2018

The homologous recombination repair (HRR) pathway is required for high-fidelity repair of double-strand DNA breaks. Cancer cells with HRR deficiency due to somatic BRCA1 or BRCA2 mutations are sensitive to platinum agents and targeted therapy with PARP inhibitors. Endometrial cancer is the most common cancer of the female reproductive system. DNA damage agents are commonly used in treatment but tumors often develop resistance. Metadherin (MTDH) has been shown to be amplified in a wide range of solid tumors as well as in leukemia and lymphoma. Overexpression of MTDH is correlated with angiogenesis, metastasis, and chemoresistance. Histone lysine N-methyl-transferase G9a catalyzes the demethylation of histone H3 at lysine residue 9 (H3K9) resulting in a repressive histone modification. The objective of this study is to validate the function of MTDH and G9a in HRR and test the potential to target MTDH or G9a to increase drug sensitivity. p21 expression was induced when G9a was depleted. DNA damage induced MTDH expression at 4 hours after 8Gy γ-irradiation in the well validated endometrial adenocarcinoma cell line Ishikawa H. However, induction of MTDH protein expression by the same radiation dosage was reduced when G9a was depleted. The G9a inhibitor UNC0642 itself can also induce the expression of MTDH after 24 hours treatment. Ishikawa parental cells and two Ishikawa sub-cell lines in which G9a was depleted by CRISPR were tested for the DNA damage biomarker γH2Ax and Rad51 foci formation at 4 hours following 8Gy irradiation. G9a depletion was shown to decrease Rad51 foci formation and to increase the formation of γH2Ax foci. Two natural products, Celastrol and Pristimerim were found to inhibit MTDH, FANCD2 and FANCI protein levels, which may be used to induce BRCA-ness in homologous recombination repair proficient cancer cells. G9a depletion results in the reduction of irradiation-induced Rad51 foci formation and an increase of irradiation-induced γH2Ax foci formation. We suggest that G9a depletion can increase cancer cell sensitivity to DNA damage agents. MTDH is induced by DNA damage and is a G9a inhibitor. MTDH depletion causes reduction of irradiation-induced Rad51 foci. This study is supported by the University of Iowa Department of Obstetrics and Gynecology Research Development Fund, NIH grant R01CA99908 and R01CA184101.

Citation Format: Xiangbing Meng, Shujie Yang, Jianling Bi, Yiyang Li, Yuping Zhang, Sudartip Areecheewaku, Mary Li, Zihan Wang, Aliasger K. Salem, Kimberly K. Leslie. Induction of HRD by targeting G9a and MTDH in DNA repair proficient endometrial cancer cells [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 4852.
Abstract 4858: Efficacy of the protein arginine methyltransferase PRMT5 inhibitor GSK591 in glioma stem-like cells
Authors: Shaw Vikram , Piao Yuji , Park Soon Young , Dong Jianwen , Martinez-Ledesma Emmanuel , Carrillo Caroline , Henry Verlene , Ezhilarasan Ravesanker , Sulman Erik , Balasubramaniyan Veerakumar , Groot John F. de
Published: August 2018

Protein arginine methyltransferase (PRMTs) function as epigenetic regulators of transcription and play a major role in gene regulation. PRMTs are upregulated in gastric, colorectal and lung cancer, and lymphoma and leukemia. PRMT5 is capable of forming symmetric dimethylarginine (SDMA) residues, and has been reported as a therapeutic target in glioblastoma, as its expression has been correlated with tumor grade and progression. In this study, the in vitro therapeutic efficacy of PRMT5 inhibitor GSK591 was investigated in a panel of gliomas stem-like cell (GSC) lines with specific molecular subtypes. Genomic, proteiomic (reverse protein lysate array, RPPA), methylation status and GSC subtype were correlated with drug IC50 to find predictors of drug sensitivity. The efficacy of inhibiting PRMT5 activity was retained at low dose of GSK591 in a small number of GSCs. Western blotting data showed high expression of PRMT5 and multiple bands of SDMAs in most GSCs tested (n=31), indicating PRMT5 enzymatic activity in GSC cell lines. Evidence of PRMT5 inhibition was demonstrated at low doses (< 1.5 uM) in 4 GSC lines (13%) as shown by the total inhibition of SDMA expression in a dose- and time-dependent fashion after GSK591 treatment. The sensitivity of GSK591 correlated with low methylation of multiple genes pretreatment, including MAGI2, EGR2, and DUSP16. In addition, upregulated genes in sensitive GSCs correlated with proliferation signatures using gene set enrichment analyses (GSEA). Together, our study demonstrated that inhibition of PRMT5 activity and its substrate product SDMA correlated with inhibition of tumor growth. These promising in vitro results have led to ongoing experiments to evaluate the efficacy of GSK591 in intracranial xenograft models and the underlying mechanism of sensitivity and resistance to PRMT5 inhibition.

Citation Format: Vikram Shaw, Yuji Piao, Soon Young Park, Jianwen Dong, Emmanuel Martinez-Ledesma, Caroline Carrillo, Verlene Henry, Ravesanker Ezhilarasan, Erik Sulman, Veerakumar Balasubramaniyan, John F. de Groot. Efficacy of the protein arginine methyltransferase PRMT5 inhibitor GSK591 in glioma stem-like cells [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 4858.
Abstract 4864: Small-molecule MDM2 antagonists attenuate the senescence-associated secretory phenotype
Authors: Schaum Nicholas , Wiley Christopher , Almirah Fatouma , Lopez-Dominguez Jose A. , Scott Gary , Benz Christopher , Campisi Judith , Davalos Albert R.
Published: August 2018

Processes that have been linked to aging and cancer include an inflammatory milieu driven by senescent cells. Senescent cells lose the ability to divide, essentially irreversibly, and secrete numerous cytokines, growth factors and proteases, termed the senescence-associated secretory phenotype (SASP). Senescent cells that lack p53 tumor suppressor function show an exaggerated SASP, suggesting the SASP is negatively controlled by p53. Here, we show that increased p53 activity caused by small molecule inhibitors of MDM2, which promotes p53 degradation, reduces inflammatory cytokine production by senescent cells. Upon treatment with the MDM2 inhibitors nutlin-3a or MI-63, human cells acquired a senescence-like growth arrest, but the arrest was reversible. Importantly, the inhibitors reduced expression of the signature SASP factors IL-6 and IL-1A by cells made senescent by genotoxic stimuli, and suppressed the ability of senescent fibroblasts to stimulate breast cancer cell aggressiveness. Our findings suggest that MDM2 inhibitors could reduce cancer progression in part by reducing the pro-inflammatory environment created by senescent cells.

Citation Format: Nicholas Schaum, Christopher Wiley, Fatouma Almirah, Jose A. Lopez-Dominguez, Gary Scott, Christopher Benz, Judith Campisi, Albert R. Davalos. Small-molecule MDM2 antagonists attenuate the senescence-associated secretory phenotype [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 4864.
Abstract 487: MicroRNA regulation of oral squamous cell carcinoma
Authors: Xiao Gary Guishan , Cao Min
Published: August 2018

Oral squamous cell carcinoma (OSCC) remains the sixth most common human cancer with high mortality rate worldwide. Understanding the molecular mechanisms is important for development of an effective treatment for the disease. MicroRNA is a short, noncoded nucleotide playing an important role in tumorigenesis and metastasis. This study is to identify novel microRNAs and their targets in order to understand the molecular mechanisms underlying OSCC and metastasis using label-free proteomics and microRNA microarray techniques. Human oral tissue biopsies from three groups of subjects who had benign, localized carcinoma and distal carcinoma were collected from the archived tissue bank at Pathology in Creighton University. Total RNA and proteins were extracted from the core biopsy of the same subject. MicroRNA identification was performed by using Affymetrix GeneChip miRNA arrays and comprehensive data analysis. Protein was analyzed by using label-free LTQ orbit trap mass spectrometry. Forty-four miRNAs were upregulated significantly, including let-7b, miR-720, miR-21, and miR-1274b, while 41 miRNAs were remarkably downregulated, including miR-195, and miR-932, at localized and distal carcinoma compared to benign tissues. Additionally, as compared to benign, 38 miRNAs upregulated at local carcinoma were downregulated significantly at distal carcinoma, while other 17 miRNAs downregulated significantly at localized carcinoma were upregulated gigantically at distal carcinoma. Those miRNAs were further validated by qRT-PCR and FISH. Among those upregulated at both local and distal, miR-720 was further studied, and tryptase alpha-1 as its target was identified. MicroRNA-720 mimics suppressed significantly the expression of tryptase alpha-1 in cultured human OSCC stem cell lines. Results from miR-720 tissue microarray analysis showed that 98.8% of sensitivity and 100% of specificity for OSCC detection were achieved, suggesting that miR-720 may be developed as a novel biomarker for detection of human OSCC.

Citation Format: Gary Guishan Xiao, Min Cao. MicroRNA regulation of oral squamous cell carcinoma [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 487.