bluuebunny/crossref_metadata_2025 huggingface dataset:
Abstract 1827: Inhibition of Src, HER2, and EGFR by the multi-kinase inhibitor KD019 overcomes trastuzumab resistance in breast cancer
Authors: Mo Rigen , Rao Nishta , Tonra James , Waksal Samuel , Poyurovsky Masha
Published: May 2015

KD019 (previously EXEL-7647) is an orally bioavailable spectrum selective small molecule kinase inhibitor of Src family nonreceptor tyrosine kinases (Src) as well as HER2, EGFR, and VEGFR2/KDR. Because of its complement of targets KD019 is able to disrupt multiple components of tumor pathology and, in earlier studies, KD019 demonstrated robust activity in multiple in vivo tumor models.

In recent years Src has emerged as a critical convergent node downstream of multiple signaling cascades initiated by transmembrane receptor tyrosine kinases (RTKs), most notably HER2, EGFR and IGF-1R. Crosstalk between Src and RTKs facilitates RTK-dependent tumor growth and, in patients with HER2-amplified (HER2+) breast cancer, where Src is upregulated, may confer resistance to anti-HER2 therapies.

Based on the target specificity of KD019, including Src, we hypothesized that KD019 may prove to be an effective treatment in overcoming trastuzumab resistance in HER2+ breast cancer. Here we present data showing that KD019 effectively inhibited growth of several trastuzumab resistant cell lines with IC50 of 0.3 uM in vitro. Not only did KD019 potently inhibit HER2 and EGFR phosphorylation in these cells, but it also efficiently inhibited the phosphorylation of c-Met through receptor hetero-oligomerization mechanism, thus downregulating another pathway by which tumors may escape HER2 targeted therapies. Further, we demonstrate that once daily dosing of KD019 strongly inhibited tumor growth in xenograft models of trastuzumab resistance and that Src activity was inhibited in KD019 treated tumors even 24 hrs after drug administration. The significance of inhibiting the specific combination of targets is underscored by the fact that KD019 was 10 fold more potent when compared to saracatinib (a selective Src inhibitor) in inhibiting growth of trastuzumab resistant cells, which are also insensitive to blockade of individual RTKs. Together, these results provide a rational for clinical investigation of KD019 in patients whose tumors are resistant to anti-HER2 therapies.

Citation Format: Rigen Mo, Nishta Rao, James Tonra, Samuel Waksal, Masha Poyurovsky. Inhibition of Src, HER2, and EGFR by the multi-kinase inhibitor KD019 overcomes trastuzumab resistance in breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1827. doi:10.1158/1538-7445.AM2014-1827
Abstract 1833: De novo EGFR T790M mutation in lung cancer patients harboring sensitive EGFR mutations
Authors: Lee Youngjoo , Lee Geon Kook , Lee Yeon-Su , Zhang Wenji
Published: May 2015

Background

EGFR T790M mutation drives acquired drug resistance to EGFR tyrosine kinase inhibitors (EGFR-TKI) in EGFR-mutant lung cancer. However, it was reported that this mutation may exist before drug exposure. This study aimed to evaluate whether the clinical outcomes are affected by the proportion of preexisting T790M mutations within a tumor.

Methods

We collected pretreatment tissues from 124 advanced non-small cell lung cancer patients with sensitizing EGFR mutations that were detected by direct sequencing. Genotyping for EGFR T790M was further performed using matrix-assisted laser desorption/ionization-time of flight/mass spectrometry. T790M-positive patients were divided to two subgroups according to T790M mutant signal frequency.

Results

The T790M mutation was found in 31 (25.0%) patients. The T790M mutation frequency at which the risk of progression to EGFR-TKI begins to increase was estimated to be 2.0%. The patients with T790M-positive tumor had shorter time to progression (TTP) after EGFR-TKI (median 6.3 months vs. 11.5 months; P < 0.001) and overall survival (OS) (median 16.1 months vs. 26.5 months; P = 0.065) than those with T790M-negative tumor. Among the T790M-positive patients, the patients with high T790M frequency (n= 9) had shorter TTP (median 2.4 months vs. 6.7 months; P = 0.009) and OS (median 9.1 months vs. 18.7 months; P = 0.018) than those with low T790M frequency (n= 22).

Conclusions

Preexisting EGFR T790M mutation was noted in 25% of patients with EGFR-mutant lung cancer. Patients with high T790M mutation frequency had worse clinical outcomes to EGFR-TKI than patients with low T790M mutation frequency.

Citation Format: Youngjoo Lee, Geon Kook Lee, Yeon-Su Lee, Wenji Zhang. De novo EGFR T790M mutation in lung cancer patients harboring sensitive EGFR mutations. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1833. doi:10.1158/1538-7445.AM2014-1833
Abstract 1841: A miR551b/catalase/MUC1/EGFR cascade for acquired apoptosis resistance and chemoresistance in lung cancer cells
Authors: Xu Xiuling , Wells Alexandria , Padilla Mabel T. , Kim Kwang Chul , Lin Yong
Published: May 2015

The oncoprotein Mucin-1 (MUC1) plays multiple roles in the development of different human tumors. However, whether MUC1 is involved in acquired chemoresistance, a major challenge in cancer therapy, has not been determined. Using a lung cancer cell model with acquired apoptosis resistance (AR)-associated chemoresistance, we investigated the role and mechanism of MUC1 in acquired chemoresistance. MUC1 expression was substantially increased in cells with acquired apoptosis resistance and knockdown of MUC1 expression effectively increased sensitivity of the AR cells to apoptotic cytotoxicity induced by anticancer therapeutics, substantiating a role for MUC1 in acquired chemoresistance. Decreased hydrogen peroxide-reducing enzyme catalase and increased cellular reactive oxygen species (ROS) were found to be associated with MUC1 overexpression. Pharmacological ROS scavengers or exogenous catalase dramatically suppressed MUC1 expression, suggesting catalase suppression-mediated ROS accumulation contributes to MUC1 overexpression. Further, we found miR-551b expression was increased in the AR cells. Knockdown of miR-551b restored catalase expression, and suppressed ROS accumulation and MUC1 expression. Finally, with manipulation of MUC1 expression, we found MUC1 promotes EGFR-mediated activation of the cell survival Akt/c-FLIP/Cox2/Mcl-1 cascade and stabilization of anti-apoptosis factors c-IAP1 and c-IAP2. Thus, our results establish a role for MUC1 in acquired chemoresistance and a pathway consisting of miR-551b/catalase/ROS for MUC1overexpression, and interventions against this pathway may be exploited for overcoming acquired chemoresistance.

Citation Format: Xiuling Xu, Alexandria Wells, Mabel T. Padilla, Kwang Chul Kim, Yong Lin. A miR551b/catalase/MUC1/EGFR cascade for acquired apoptosis resistance and chemoresistance in lung cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1841. doi:10.1158/1538-7445.AM2014-1841
Abstract 1853: Piwi-like 1 and -4 gene transcript levels are associated with clinicopathological parameters in renal cell carcinomas
Authors: Al-Janabi Omar , Wach Sven , Nolte Elke , Weigelt Katrin , Rau Tilman T. , Stöhr Christine , Legal Wolfgang , Schick Stefan , Greither Thomas , Hartmann Arndt , Wullich Bernd , Taubert Helge W.
Published: May 2015

Background: Piwi-like gene family members (Piwil 1-4) are considered stem cell-associated genes/proteins. These are expressed predominantly in germline cells, but are re-expressed in different tumors. Piwil 1-4 gene expression has not previously been studied and correlated with clinicopathological parameters in renal cell carcinomas (RCC).

Material and Methods: The Piwil 1-4 transcript levels were analyzed by quantitative real-time PCR in 74 clear cell RCC (ccRCC) tissues and corresponding normal tissues.

Results: The transcript levels of Piwil 1, 2 and 4 were strongly and significantly correlated with each other, but not with Piwil 3, in both the tumor tissues and the normal tissues (P < 0.001; Spearman's rank test). Piwil 4 gene expression was significantly higher in the ccRCC tissues than in the corresponding normal renal tissues (P < 0.001; Wilcoxon signed-rank test). When the ccRCC patient cohort was divided according to the median Piwil 1-4 expression into low and high-expression groups and according to age into younger (≤ 64 years) and older patient groups (>64 years), the younger patients displayed significantly higher levels of Piwil 1 mRNA in comparison to the older patients (P = 0.010; Fisher's exact test). Interestingly, Piwil 1 expression was left-right polarized in the normal tissues but not in the tumor tissues (P = 0.0005; Fisher's exact test).

Conclusions: Altogether, associations were determined between the Piwi-like family member expression levels and clinicopathological parameters of ccRCC, suggesting a potential role for these genes/proteins in ccRCC diagnostics and tumorigenesis, as well as in renal tissue embryology.

Citation Format: Omar Al-Janabi, Sven Wach, Elke Nolte, Katrin Weigelt, Tilman T. Rau, Christine Stöhr, Wolfgang Legal, Stefan Schick, Thomas Greither, Arndt Hartmann, Bernd Wullich, Helge W. Taubert. Piwi-like 1 and -4 gene transcript levels are associated with clinicopathological parameters in renal cell carcinomas. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1853. doi:10.1158/1538-7445.AM2014-1853
Abstract 1863: Androgen receptor CAG repeat length and TMPRSS2:ETS prostate cancer risk: results from the Prostate Cancer Prevention Trial
Authors: Price Douglas K. , Chau Cindy H. , Figg William D. , Till Catherine A. , Goodman Phyllis J. , Cho Yonggon , Garcia Marileila , Reichardt Juergen , Tangen Catherine M. , Leach Robin J. , Bokhoven Adrie van , Kristal Alan R. , Thompson Ian M. , Lucia M Scott
Published: May 2015

Recent evidence suggests that genetic variations within the androgen receptor (AR) may influence the formation of TMPRSS2:ETS gene fusions, which are detected in more than half of all prostate cancers. We investigated the association between the length of the polymorphic trinucleotide CAG microsatellite repeats in exon 1 of the AR gene and risk of prostate cancer containing these fusion genes. This nested case-control study came from subjects enrolled in the Prostate Cancer Prevention Trial and included 195 biopsy-proven prostate cancer cases with known TMPRSS2:ETS status and 1344 matched controls. There was no association between CAG repeat length and risk of TMPRSS2:ETS-positive (OR=0.97, 95% CI, 0.91-1.04) or TMPRSS2:ETS-negative prostate cancer (OR=1.04, 95% CI, 0.97-1.10) and in patients with low- or high-grade disease. Our findings suggested that AR CAG repeats are not associated with TMPRSS2:ETS formation in prostate cancer.

Citation Format: Douglas K. Price, Cindy H. Chau, William D. Figg, Catherine A. Till, Phyllis J. Goodman, Yonggon Cho, Marileila Garcia, Juergen Reichardt, Catherine M. Tangen, Robin J. Leach, Adrie van Bokhoven, Alan R. Kristal, Ian M. Thompson, M Scott Lucia. Androgen receptor CAG repeat length and TMPRSS2:ETS prostate cancer risk: results from the Prostate Cancer Prevention Trial. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1863. doi:10.1158/1538-7445.AM2014-1863
Abstract 1866: Detection of early-stage lung cancer using a novel ELISA for thymidine kinase 1
Authors: Ramsden Madison K. , Alegre Melissa M. , Weyant Michael J. , Bennett Daine T. , Yu Jessica A. , Elnaggar Atif , Robison Richard A. , O'Neill Kim L.
Published: May 2015

Lung cancer is the number one cause of cancer mortality and early detection will increase the survival of this disease. Thymidine kinase 1 (TK1) is a biomarker indicative of cell proliferation that is elevated in numerous malignancies including lung cancer. TK1 has been found to be elevated early in the development of lung cancer and therefore is an ideal target as an early detection biomarker. We have developed an enzyme-linked immunosorbent assay (ELISA) to detect TK1 in serum. Forty patients with pulmonary nodules and 18 healthy control individuals had serum collected under standard conditions, prior to operative removal of any lesions. All serum samples were analyzed using TK1 radioassay to measure TK1 activity, and TK1 ELISA to measure TK1 concentration. TK1 was significantly elevated in all patients with confirmed lung cancer. This was true even in stage IA, where patients (n=16) had significantly higher TK1 levels than controls. The clearest cut-off was 4.9 nM with an area under the curve of 0.792 for early stage lung cancer. The corresponding sensitivity and specificity was 82.4 and 83.3, respectively. TK1 concentration was a more sensitive and accurate indicator of lung cancer than TK1 activity. Overall, TK1 is significantly elevated in serum of lung cancer patients. This TK1 ELISA is sensitive and specific for detection of lung cancer and further trials with a larger patient base can confirm the potential of this method of detection.

Citation Format: Madison K. Ramsden, Melissa M. Alegre, Michael J. Weyant, Daine T. Bennett, Jessica A. Yu, Atif Elnaggar, Richard A. Robison, Kim L. O'Neill. Detection of early-stage lung cancer using a novel ELISA for thymidine kinase 1. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1866. doi:10.1158/1538-7445.AM2014-1866
Abstract 1891: Mutations in polymerase ϵ as key molecular alteration of the novel ultramutator phenotype do not define a clinically distinct entity of colorectal cancer
Authors: Stenzinger Albrecht , Volker Endris , Pfarr Nicole , Penzel Roland , Jansen Lina , Herpel Esther , Roth Wilfried , Bläker Hendrik , Chang-Claude Jenny , Brenner Hermann , Hoffmeister Michael , Weichert Wilko
Published: May 2015

Background: Recent molecular profiling studies reported a new class of ultramutated colorectal cancers (CRC), which are likely caused by exonuclease domain (END) mutations in DNA polymerase ϵ (POLE). However, data on the clinical implications of these biological findings as to whether these mutations in analogy to endometrial cancer define a unique CRC entity with distinct clinical outcome is entirely lacking.

Methods: We performed Sanger sequencing of the POLE END in 431 well annotated microsatellite stable (MSS) CRCs of a population-based epidemiological case-control study (DACHS). Mutation data were correlated with major epidemiological, clinical, genetic and pathological parameters including overall and disease-specific survival.

Results: In 373 out of 431 MSS CRC all exons of POLE END were analyzable. 47 mutations in the END of POLE were identifiable in 41 of these samples (11%). Besides already reported mutations affecting the codons 459, 411 and 286, we found many new mutations in exons 13 and 14 (corresponding to codons 411-491 of the END) as well as in exon 12 (corresponding to codons 268-301 of the END), which have not been reported yet. However, we found no associations of POLE END mutations with clinicopathological parameters, including sex, age, tumor location and tumor stage, CIMP, RAS and BRAF mutations. Survival analysis by cox regression revealed adjusted (for sex, age, tumor location and therapy) HRs of 1.38 and 1.44 for disease-specific and overall survival indicating slightly impaired survival of patients with mutations in POLE END, however, these differences were not statistically significant. This was also true for the subgroups of different exons, known/new, potentially damaging/non-damaging mutations and the type of mutation.

Conclusions: In contrast to endometrial cancer, somatic POLE mutations do not appear to define a clinically strongly distinct disease entity in CRC.

Citation Format: Albrecht Stenzinger, Endris Volker, Nicole Pfarr, Roland Penzel, Lina Jansen, Esther Herpel, Wilfried Roth, Hendrik Bläker, Jenny Chang-Claude, Hermann Brenner, Michael Hoffmeister, Wilko Weichert. Mutations in polymerase ϵ as key molecular alteration of the novel ultramutator phenotype do not define a clinically distinct entity of colorectal cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1891. doi:10.1158/1538-7445.AM2014-1891
Abstract 1906: FOXC1 regulates cancer stem cells properties via inducing SMO-independent Gli activation and confers anti-Hedgehog drug resistance in basal-like breast cancer
Authors: Han Bingchen , Jin Yanli , Bose Shikha , Zhang Xiao , Qu Ying , Karlan Beth Y. , Giuliano Armando E. , Cui Xiaojiang
Published: May 2015

Basal-like breast cancer (BLBC), an aggressive subtype of breast cancer, are usually associated with high histologic grade, high recurrence rate, short recurrence-free survival, younger patient age, poor outcome, and a propensity to metastasize to the brain and lung. So far, developing targeted therapies against BLBC still remains a great challenge. Uncovering the underlying molecular events and identify therapeutic target becomes highly urgent. Forkhead Box C1 (FOXC1), a biomarker for BLBC, is associated with poor prognosis in patients with BLBC. Here, we found that FOXC1 increases cancer stem cells (CSCs) properties in BLBC cells in vitro and in vivo. FOXC1 activates SMO-independent non-canonical Hedgehog (Hh) signaling pathway, which mediates the effects of FOXC1 on CSCs properties in BLBC cells. Further study showed that the N-terminal of FOXC1 bind directly to the Gli2 transcription factor, which has the highest transcriptional activity in Hh signaling pathway. Here we also found that the elevated expression of FOXC1 induces anti-Hh pathway drug resistance. All of these data demonstrate a novel mechanism underlying the regulation of CSC properties and the poor prognosis of BLBC patients, and may provide new insight into anti-CSC therapy resistance. Thus, our study provides a strong rationale for developing FOXC1-targeted therapy for treating BLBC patients.

Citation Format: Bingchen Han, Yanli Jin, Shikha Bose, Xiao Zhang, Ying Qu, Beth Y. Karlan, Armando E. Giuliano, Xiaojiang Cui. FOXC1 regulates cancer stem cells properties via inducing SMO-independent Gli activation and confers anti-Hedgehog drug resistance in basal-like breast cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1906. doi:10.1158/1538-7445.AM2014-1906
Abstract 1913: C/EBPdelta links hypoxia and inflammation to the promotion of tumor cell stemness through inhibition of FBXW7: A molecular target for HDAC inhibitor action
Authors: Balamurugan Kuppusamy , Summers Glenn H. , Sharan Shikha , Sterneck Esta
Published: May 2015

Hypoxia and inflammation are linked to progression of epithelial cancers by promoting epithelial-mesenchymal transition (EMT) and cancer stem cells (CSCs). A better understanding of the mechanisms by which these conditions augment tumor progression is necessary to combat metastases and treatment resistance. The transcription factor C/EBPδ promotes hypoxia adaptation and inflammatory signaling by inhibiting expression of FBXW7, which targets many oncoproteins (e.g. Notch, c-myc) and also C/EBPδ for degradation (Balamurugan et al., EMBO J, 2010; Nature Commun 2013). FBXW7 is also known to regulate self-renewal, differentiation and quiescence of neural and hematopoietic stem cells. Therefore, we hypothesized that C/EBPδ supports the development of CSCs through inhibition of FBXW7 and that this pathway has potential as therapeutic target.

We investigated the roles of C/EBPδ and FBXW7 through overexpression and silencing approaches in human breast tumor cell lines and primary mouse mammary tumors; followed by gene expression analyses and assays for stem cell-like functions under hypoxia and in response to interleukin 6 (IL-6). We found that C/EBPδ augments _ while FBXW7 inhibits _ hypoxia- and IL-6-induced formation of mammospheres, a surrogate assay for stem cell function, and expression of markers for EMT and CSCs. Furthermore, C/EBPδ was necessary for hypoxia-induced expression of IL-6, providing a link between these pathways. Indeed, silencing of C/EBPδ delayed the outgrowth of MCF-7 xenograft tumors, indicating that C/EBPδ supports CSC development.

Because C/EBPδ can interact with histone deacetylases (HDACs), we tested the effect of HDAC inhibitors (HDACi) that are in clinical trials for breast cancer (e.g. SAHA). HDACi inhibited C/EBPδ expression and induced FBXW7 expression. Furthermore, HDACi reduced mammosphere formation specifically under hypoxia, and this effect could be partially reversed by FBXW7 knockdown. These results suggest a therapeutic benefit of HDACi for breast cancer through activation of FBXW7 and inhibition of C/EBPδ followed by reduction in CSCs. Future investigations will explore drug combinations with HDACi to maximize the effectiveness of the FBXW7 tumor suppressor pathway under hypoxia and inflammatory conditions.

Citation Format: Kuppusamy Balamurugan, Glenn H. Summers, Shikha Sharan, Esta Sterneck. C/EBPdelta links hypoxia and inflammation to the promotion of tumor cell stemness through inhibition of FBXW7: A molecular target for HDAC inhibitor action. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1913. doi:10.1158/1538-7445.AM2014-1913
Abstract 1957: Slug regulates SOX9 stability in lung carcinoma and its involvement in the regulation of cancer stem cells and lung metastasis
Authors: Luanpitpong Sudjit , Wang Liying , Rojanasakul Yon
Published: May 2015

Most solid tumors including lung carcinoma are believed to contain cancer stem cells (CSCs) that are responsible for tumor initiation, progression, and metastasis. Understanding how CSCs are regulated at the molecular level may lead to novel strategies for cancer therapy. We have identified two proteins, Slug and SOX9, which determine the CSC state of human lung cancer epithelial cells. Inhibition of either Slug or SOX9 sufficiently blocks CSCs in human lung carcinoma cell lines, as determined by side population and tumor sphere assays, and attenuates lung metastasis in vivo in a xenograft mouse model. Coexpression of Slug and SOX9 is detected in the majority of lung tissues with advanced stage carcinoma. Here we found for the first time that Slug regulates SOX9 stability. Loss of Slug results in SOX9 degradation through ubiquitin-proteasomal pathway, and overexpression of Slug conversely prevents SOX9 degradation. Together, our results provide a direct evidence for the control of CSCs and tumor progression by Slug and SOX9, and unveil a novel role of Slug in SOX9 stabilization. These findings provide a mechanistic insight to the pathogenesis of metastasis in advanced lung carcinoma.

Citation Format: Sudjit Luanpitpong, Liying Wang, Yon Rojanasakul. Slug regulates SOX9 stability in lung carcinoma and its involvement in the regulation of cancer stem cells and lung metastasis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1957. doi:10.1158/1538-7445.AM2014-1957
Abstract 1959: Lgr5 marks an enriched population of fetal mammary stem cells
Authors: Trejo Christy L. , Spike Ben , Wahl Geoff
Published: May 2015

Basal-like breast cancers have unique characteristics that may contribute to their particularly poor prognosis. These include a high degree of genomic instability, intra-tumor heterogeneity, and gene expression profiles similar to those of normal mammary stem cells. These characteristics may arise through the aberrant propagation of normal stem cells. Alternatively, mutations commonly found in this subtype may be the dominant determinant of tumor phenotype. In order to explore these possibilities, pure populations of stem cells need to be isolated and analyzed. Our lab has identified a population of fetal mammary stem cells (fMaSCs) in the mouse whose gene expression profiles show a striking enrichment for those of human basal tumors. When fMaSCs were targeted with a p53 mutation, commonly found in human basal cancer, a tumor arose within 5 weeks- the shortest latency we have observed from any cell type. This suggests that fMaSCs are particularly prone to tumorigenesis and may likely be a source of basal-like tumors in the adult. Mammary stem cell activity becomes detectable at a defined time in late embryonic development, peaks right before birth, diminishes rapidly at birth, and remains low in the adult. We have since identified Lgr5 to be highly expressed in fMaSCs at the peak of their stem cell activity. We have gone on to use it to isolate the most pure population of fMaSCs measured yet by in vitro means. When plated in 3D culture containing 2% matrigel, up to 50% of Lgr5-expressing fetal mammary cells formed correctly polarized mammospheres.

Using three independent methods, we will determine how Lgr5 expression tracks with stem cell activity throughout development and use this marker to test for the persistence of fetal-like stem cells in the adult mammary gland. We will develop comprehensive gene expression profiles from Lgr5+ cells throughout development to identify molecular correlates of the stem cell state. The relative contributions of developmental state of cell of origin or mutational status to tumor phenotype are poorly understood. We will test the capacity of stem cells at various stages of development to give rise to tumors when targeted with mutations commonly found in human basal tumors. A thorough analysis of tumors will reveal links between development, tumor initiation and progression, and provide insight into strategies to treat basal breast cancers.

Citation Format: Christy L. Trejo, Ben Spike, Geoff Wahl. Lgr5 marks an enriched population of fetal mammary stem cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1959. doi:10.1158/1538-7445.AM2014-1959
Abstract 1964: Masitinib antagonizes ATP-binding cassette subfamily c member 10-mediated paclitaxel resistance: a preclinical study
Authors: Kathawala Rishil , Sodani Kamlesh , Chen Kang , Patel Atish , Abuznait Alaa , Anreddy Nagaraju , Sun Yue-Li , Kaddoumi Amal , Ashby Charles R. , Chen Zhe-Sheng
Published: May 2015

Paclitaxel displays clinical activity against a wide variety of solid tumors. However, resistance to paclitaxel significantly attenuates the response to chemotherapy. The ABC transporter subfamily C member 10 (ABCC10), also known as multi-drug resistance protein 7 (MRP7) efflux transporter, is a major mediator of paclitaxel resistance. In this study, we show that masitinib, a small molecule stem-cell growth factor receptor (c-Kit) tyrosine kinase inhibitor, at non-toxic concentrations, significantly attenuates paclitaxel resistance in HEK293 cells transfected with ABCC10. Our in vitro studies indicated that masitinib (2.5 μM) enhanced the intracellular accumulation and decreased the efflux of paclitaxel by inhibiting the ABCC10 transport activity without altering the expression level of ABCC10 protein. Furthermore, masitinib, in combination with paclitaxel, significantly inhibited the growth of ABCC10-expressing tumors in nude athymic mice in vivo. Masitinib administration also resulted in a significant increase in the levels of paclitaxel in the plasma, tumors and lungs compared to paclitaxel alone. In conclusion, the combination of paclitaxel and masitinib could serve as a novel and useful therapeutic strategy to reverse paclitaxel resistance mediated by ABCC10.

Citation Format: Rishil Kathawala, Kamlesh Sodani, Kang Chen, Atish Patel, Alaa Abuznait, Nagaraju Anreddy, Yue-Li Sun, Amal Kaddoumi, Charles R. Ashby, Zhe-Sheng Chen. Masitinib antagonizes ATP-binding cassette subfamily c member 10-mediated paclitaxel resistance: a preclinical study. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1964. doi:10.1158/1538-7445.AM2014-1964
Abstract 1967: A-803467, a sodium channel blocker, reverses ABCG2-mediated MDR
Authors: Anreddy Nagaraju
Published: May 2015

The ATP-binding cassette, subfamily G, isoform 2 protein (ABCG2) is a vital member of the ABC transporter superfamily, which has been involved in multidrug resistance (MDR) in cancer. Its diverse range of substrates includes many antineoplastic agents such as doxorubicin and mitoxantrone. ABCG2 expression has been significantly increased in some solid tumors and hematologic malignancies, which is correlated to poorer clinical outcomes. In addition, ABCG2 expression is a distinguishing feature of cancer stem cells, whereby this membranous transporter imparts resistance to the chemotherapeutic drugs. To enhance the chemosensitivity of cancer cells, attention has been focused on MDR modulators. In this study, we investigated the ability of sodium channel blocker, A-803467 to reverse ABCG2-mediated MDR. We found that A-803467 at non-toxic concentration could significantly increase the cellular sensitivity to ABCG2 substrates in drug-resistant cells overexpressing either wild-type or mutant ABCG2. Mechanistic studies indicated that A-803467 (7.5 μM) significantly increased the intracellular accumulation resulted from inhibition of the efflux of mitoxantrone by inhibiting the transport activity without altering expression level of ABCG2 protein. Furthermore, ATPase analysis indicates that A-803467 stimulates the ATPase activity in membranes overexpressing ABCG2. Our findings suggest that A-803467 has the potential to be used in combination with ABCG2 chemotherapeutic substrates to augment the response in drug resistant cancers.

Citation Format: Nagaraju Anreddy. A-803467, a sodium channel blocker, reverses ABCG2-mediated MDR. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1967. doi:10.1158/1538-7445.AM2014-1967
Abstract 1978: The tyrosine kinase Syk plays a role in the maintenance of intercellular adhesive junctions in human breast cancer cells
Authors: Kassouf Toufic , Montcourrier Philippe , Larive Romain , Bettache Nadir , Morel Anne , Merezegue Fabrice , Urbach Serge , Coopman Peter J.
Published: May 2015

The non-receptor spleen tyrosine kinase Syk has mainly been studied in hematopoietic cells in which it plays a key role in the immune-response signalling. We previously demonstrated that Syk is also present in mammary epithelial cells and that its expression is lost during malignant progression of breast cancer cell lines. Clinical studies confirmed loss of Syk expression, not only in breast tumors but also in other carcinomas and melanoma. Xenotransplantation animal experiments evidenced that Syk acts as a tumor and metastasis suppressor in breast cancer and melanoma. The mechanisms by which Syk exerts its anti-oncogenic activity remain, however, unrevealed. Using a quantitative phospho-proteomic SILAC approach in breast cancer cells, we identified new potential Syk substrates involved in intercellular adhesion and epithelial cell polarity, both characters of cell differentiation that are lost during tumor progression.

Using in vitro kinase assays, we demonstrated that E-cadherin and various catenins are direct Syk substrates. The tyrosine residues phosphorylated by Syk were identified by mass spectrometry and phospho-peptide-specific antibodies were generated. By immunofluorescence, we observed that endogenous Syk and E-cadherin colocalize at adherens junctions and that transient DsRed-Syk transfection induces phospho-E-cadherin- and phospho-catenin epitopes at cell-cell contacts. Immunoprecipitation experiments indicate that phosphorylated E-cadherin and catenins are associated in a complex. Syk-mediated phosphorylation of E-cadherin seems to be important for the proper localization of p120-catenin at adherens junctions. Syk knockdown in breast cancer cells partially inhibits the re-aggregation of cells and increases invasion in Matrigel. Using Syk knockdown and overexpression we explored its potential role in the maintenance of an epithelial phenotype, preventing EMT.

In conclusion, Syk might play a role in the establishment and maintenance of intercellular junctions via the phosphorylation of the E-cadherin/catenin complex. Loss of Syk expression or function might lead to the destabilization of these complexes and promote invasion (supported by Fondation ARC SL220110603480)

Citation Format: Toufic Kassouf, Philippe Montcourrier, Romain Larive, Nadir Bettache, Anne Morel, Fabrice Merezegue, Serge Urbach, Peter J. Coopman. The tyrosine kinase Syk plays a role in the maintenance of intercellular adhesive junctions in human breast cancer cells. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1978. doi:10.1158/1538-7445.AM2014-1978
Abstract 198: Ex vivo expansion of hematopoietic stem cells in nonhuman primate using optimal cytokine combinations
Authors: Zhang Yu , Shen Bin , Ren Zhihua , Dai Wei , Ma Yupo , Jiang Yongping
Published: May 2015

Hematopoietic stem cell (HSC) or hematopoietic progenitor cell (HPC) transplantation has been widely accepted for the treatment of malignant blood diseases, as well as immunological disorders. Due to insufficient amounts of HLA-matched stem/progenitor cells, multiple strategies have been developed for expansion of hematopoietic stem cells ex vivo in the past. Here, we report for the first time that HSCs/HPCs from cynomolgus could be expanded at a high efficiency with an optimal cytokine combination. CD34+ cells were isolated from mobilized peripheral blood (PB) of cynomolgus (n=4) that had received a joint application of rhG-CSF (200 µg/kg) and rhSCF (200 µg/kg) s.c. for 5 (successive) days. Peripheral blood (15 ml each) was collected 24 and 48 h after the final injection of cytokines. A liquid suspension culture system that contained SCF, TPO, FL, IL-3, G-CSF and GM-CSF was employed for CD34+ cells expansion. We observed that PB-derived HSCs/HPCs underwent a significant expansion by day 15 of culture. Total nucleated cells were expanded for 1839 folds (Mean value) by day 33 whereas CD34+ cells increased about 80 folds (Mean value) by day 28. Further in vivo studies will be carried out to evaluate short-term and long-term engraftments of ex vivo expanded CD34+ cells. Nevertheless, our current study demonstrates that optimal cytokine combinations can be used for promoting CD34+ cell expansion efficiently ex vivo in a non-human primate model. This line of study is likely to provide an effective approach for expansion of human hematopoietic stem cells for various therapeutic applications.

Citation Format: Yu Zhang, Bin Shen, Zhihua Ren, Wei Dai, Yupo Ma, Yongping Jiang. Ex vivo expansion of hematopoietic stem cells in nonhuman primate using optimal cytokine combinations. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 198. doi:10.1158/1538-7445.AM2014-198
Abstract 1987: The role of lipolysis-stimulated lipoprotein receptor in directing breast cancer cell behavior and subtype
Authors: Fleming Jodie M. , Reaves Denise K. , Fagan-Solis Katerina D. , Dunphy Karen , Oliver Shannon D.
Published: May 2015

The claudin-low molecular subtype of breast cancer is of particular interest for clinically the majority of these tumors are poor prognosis, triple negative, invasive ductal carcinomas. Claudin-low tumors are characterized by low gene expression of cell junction and adhesion proteins, and de-regulation of tight junction proteins is often been implicated in tumorigenesis. Herein, we sought to define the role of tricellular tight junction (tTJ) proteins in breast cancer and cancer cell behavior with a focus on lipolysis-stimulated lipoprotein receptor (LSR). LSR was expressed in epithelium, endothelium, adipose and stromal cells within the healthy breast tissue, as well as in tumor epithelium. LSR expression was significantly correlated with invasive ductal carcinomas compared to invasive lobular carcinomas, and ERα positive tumors and breast cancer cell lines. Consistent with the role of LSR in tTJs, LSR levels were significantly reduced in claudin-low breast cancer cell lines. Functional studies illustrated that that re-introduction of LSR into a claudin-low cell line suppressed the EMT phenotype and reduced individual cell migration. However, our data suggest that LSR may direct collective cell migration. Moreover, re-introduction of LSR in claudin-low breast cancer cell lines reestablished a family of TJ expression, thereby reverting claudin-low lines to other molecular subtypes. Overexpression of LSR enhanced proliferation and survival in anchorage independent conditions, suggesting that reestablishment of tight junctions is not sufficient to inhibit aggressive cell behaviors in vitro. Collectively, these data highlight an unanticipated role for the tTJ protein, LSR in directing aggressive breast cancer behavior.

Citation Format: Jodie M. Fleming, Denise K. Reaves, Katerina D. Fagan-Solis, Karen Dunphy, Shannon D. Oliver. The role of lipolysis-stimulated lipoprotein receptor in directing breast cancer cell behavior and subtype. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1987. doi:10.1158/1538-7445.AM2014-1987
Abstract 1991: Axl overexpression drives migration and invasion in colon cancer
Authors: Uribe Diana J. , Bosurgi Lidia , Gagliani Nicola , Joannas Leonel , Watson Adam , Martinez Jesse D. , Rothlin Carla V. , Ghosh Sourav
Published: May 2015

Receptor tyrosine kinases (RTK) of the TAM family have been described as oncogenes. Axl and Mertk, two members of the TAM family, are also potent negative regulators of the inflammatory response. Inflammation is an enabling characteristic of cancer hallmarks and can promote tumorigenesis and tumor progression. Genetic ablation of Axl and Mertk in mice, results in heightened inflammation in the gut and increased susceptibility to inflammation-driven colon cancer (azoxymethane/dextran sodium sulfate treatment paradigm). We sought to understand the role of Axl and Mertk, individually, in colon cancer cells to identify the key TAM oncogene in this disease.

Here we show that Axl, but not Mertk, was highly expressed and correlated with grade of metastatic colon cancer. Silencing Axl expression in RKO-AS45-1 and HCT116 colon cancer cells had no significant effect on proliferation and survival, but markedly decreased migration and invasion. R428, a selective Axl small molecule inhibitor, also drastically reduced migration in these colon cancer cell lines. Analyses of Axl knockout mice revealed that single, genetic ablation of this TAM RTK does not increase susceptibility to DSS-induced colitis, in contrast to that observed in Axl and Mertk double knockout mice.

These results are consistent with a redundant function of Axl and Mer in the regulation of the inflammatory response. Our findings suggest that the selective targeting of Axl in colon cancer might disable the oncogenic function of TAM RTKs, while sparing the protective, anti-inflammatory function of this RTK family in this disease.

Citation Format: Diana J. Uribe, Lidia Bosurgi, Nicola Gagliani, Leonel Joannas, Adam Watson, Jesse D. Martinez, Carla V. Rothlin, Sourav Ghosh. Axl overexpression drives migration and invasion in colon cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1991. doi:10.1158/1538-7445.AM2014-1991
Abstract 1992: Y-box protein-associated acidic protein promotes breast cancer progression and is a potential molecular target
Authors: Scully Olivia J. , Thike Aye Aye , Yip George Wai-Cheong , Tan Puay Hoon , Matsumoto Ken , Bay Boon Huat
Published: May 2015

The Y-Box protein- associated acidic protein (YBAP1), also known as Complement component 1, q subcomponent binding protein, is a multifunctional protein which is involved in in the regulation of complement activation, pre-mRNA splicing and mitochondrial function. As YBAP1 has been implicated in tumorigenesis, this study evaluates its role in breast cancer metastasis. YBAP1 mRNA expression was analysed by quantitative real time RT-PCR and YBAP1 protein by Western blot, immunocytochemical and immunofluorescence staining in a panel of breast cancer cell lines. Down-regulation of the YBAP1 gene in MDA-MB-231 breast cancer cells was performed by siRNA-mediated silencing and overexpression of the gene by transfection with the pCI-neo-YBAP1 plasmid, before analysis of the effects on cell migration and invasion. YBAP1 gene profiling was also performed in samples from the commercially available TissueScan Human Breast Cancer Panel 1 (Origene, Rockville, MD). YBAP1 immunohistochemical staining was carried out in breast cancer tissue microarrays constructed from 168 patients diagnosed with invasive ductal breast carcinoma. The YBAP1 immunostaining was performed using rabbit polyclonal anti-YBAP1 (RIKEN) at a dilution of 1:500. The percentage and intensity of YBAP1 immunopositive staining in malignant epithelial cells were recorded. YBAP1 was observed to be expressed in all the breast cancer cell lines (MCF-7, ZR-75, T47D and MDA-MB-231) examined. The protein was observed to be localized in the cytoplasm of breast cancer cells. Overexpression of YBAP1 increased cell migration and invasion in the highly malignant MDA-MB-231 breast cancer cells. Conversely silencing of the YBAP1 gene had the opposite effect, resulting in reduced cell migration and invasion. YBAP1 gene expression was also found to be up-regulated in the more advanced stages of breast cancer (grouped as Stage 0, I and IIa and compared with Stage II b, IIIa and IIIc; P <0.05). For the tissue microarrays, a positive correlation was observed between YBAP1 immunostaining and axillary lymph node status. YBAP1 augments the spread of breast cancer by enhancing cell migration and invasion. Hence, YBAP1 is a potential metastatic biomarker and targeting YBAP1 could be a strategy to combat breast cancer metastasis.

Citation Format: Olivia J. Scully, Aye Aye Thike, George Wai-Cheong Yip, Puay Hoon Tan, Ken Matsumoto, Boon Huat Bay. Y-box protein-associated acidic protein promotes breast cancer progression and is a potential molecular target. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1992. doi:10.1158/1538-7445.AM2014-1992
Abstract 1994: Cd44s is of functional importance for hepatocellular carcinoma (hcc) extra-hepatic metastases through activation of sdf-1a/cxcr4 axis
Authors: Zhu Wenwei , Guo Lei , Ye Qinhai
Published: May 2015

Background: CD44 has been reported as a promoter of metastasis in several tumors, including HCC. In this study, we elucidated the critical role of CD44 in HCC metastasis, especially in distant metastasis as well as the underling mechanism.

Methods: The expression of CXCR4, CD44 and their associated cellular signaling cascades, involving Akt and MAP Kinases, were determined by Western blotting. We also established CD44-deficient MHCC-97H cell lines by transfection with miRNA-CXCR4 plasmids and determined cell migration/invasion activity in a transwell assay.The prognostic value of CD44 and it's combination with CXCR4 was further evaluated.

Results: HCC patients with higher CD44 have poor prognosis, including reduced disease-free and overall survival, and individuals with distinct metastasis have higher frequency expression of CD44. We found that expression of CD44 was positively related to metastatic potential of HCC cell lines, and modified cells with CD44high showed higher aggressiveness in vitro, and higher metastatic ability in vivo. Furthermore, the mechanism of CD44 improving the invasion activity of HCC cells was though the SDF-1a/CXCR4 axis. CD44 can activate the PI-3K/Akt pathway through binding HA, which can up-regulate the expression of CXCR4. CD44 combined with CXCR4 is a promising independent predictor of tumor recurrence and survival in hepatocellular carcinoma patients.

CONCLUSIONS: CD44s is a potent predictor for extra-hapatic metastasis and overall survival of HCC patients. Our findings also provided evidence that the process of HA/CD44-induced CXCR4 expression is functional important for the invasiveness and metastasis of HCC. Therefore, the CD44-SDF-1α/CXCR4 system may be a new therapeutic target for treating HCC metastasis.

Note: This abstract was not presented at the meeting.

Citation Format: Wenwei Zhu, Lei Guo, Qinhai Ye. Cd44s is of functional importance for hepatocellular carcinoma (hcc) extra-hepatic metastases through activation of sdf-1a/cxcr4 axis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1994. doi:10.1158/1538-7445.AM2014-1994