Copland, John A.

Abstract Purpose: We set out to identify Stearoyl-CoA desaturase 1 (SCD1) as a novel molecular target in clear cell renal cell carcinoma (ccRCC) and examine its role in tumor cell growth and viability in vitro and in vivo independently as well as in combination with current U.S. Food and Drug Administration (FDA)-approved regimens. Experimental Design: Patient normal and ccRCC tissue samples and cell lines were examined for SCD1 expression. Genetic knockdown models and targeted inhibition of SCD1 through use of a small molecule inhibitor, A939572, were analyzed for growth, apoptosis, and alterations in gene expression using gene array analysis. Therapeutic models of synergy were evaluated utilizing pharmacologic inhibition of SCD1 with the tyrosine kinase inhibitors (TKI) sunitinib and pazopanib, and the mTOR inhibitor temsirolimus. Results: Our studies identify increased SCD1 expression in all stages of ccRCC. Both genetic knockdown and pharmacologic inhibition of SCD1 decreased tumor cell proliferation and induced apoptosis in vitro and in vivo. Upon gene array, quantitative real-time PCR, and protein analysis of A939572-treated or SCD1 lentiviral knockdown samples, induction of endoplasmic reticulum stress response signaling was observed, providing mechanistic insight for SCD1 activity in ccRCC. Furthermore, combinatorial application of A939572 with temsirolimus synergistically inhibited tumor growth in vitro and in vivo. Conclusions: Increased SCD1 expression supports ccRCC viability and therefore we propose it as a novel molecular target for therapy either independently or in combination with an mTOR inhibitor for patients whose disease cannot be remedied with surgical intervention, such as in cases of advanced or metastatic disease. Clin Cancer Res; 19(9); 2368–80. ©2013 AACR.

Pazopanib and paclitaxel produce cytotoxic synergy in thyroid cancer models through inhibition of aurora kinase A.

Abstract PRSS3/mesotrypsin is an atypical isoform of trypsin that has been associated with breast, lung, and pancreatic cancer cell malignancy. In analyses of open source transcriptional microarray data, we find that PRSS3 expression is upregulated in metastatic prostate cancer tissue, and that expression of PRSS3 in primary prostate tumors is prognostic of systemic progression following prostatectomy. Using a mouse orthotopic model with bioluminescent imaging, we show that PRSS3/mesotrypsin is critical for prostate cancer metastasis. Silencing of PRSS3 inhibits anchorage-independent growth of prostate cancer cells in soft agar assays, and suppresses invasiveness in Matrigel transwell assays and three-dimensional (3D) cell culture models. We further show that treatment with recombinant mesotrypsin directly promotes an invasive cellular phenotype in prostate cancer cells and find that these effects are specific and require the proteolytic activity of mesotrypsin, because neither cationic trypsin nor a mesotrypsin mutant lacking activity can drive the invasive phenotype. Finally, we show that a newly developed, potent inhibitor of mesotrypsin activity can suppress prostate cancer cell invasion to a similar extent as PRSS3 gene silencing. This study defines mesotrypsin as an important mediator of prostate cancer progression and metastasis, and suggests that inhibition of mesotrypsin activity may provide a novel modality for prostate cancer treatment. Mol Cancer Res; 10(12); 1555–66. ©2012 AACR.

Abstract Bladder cancer is the 4th most commonly diagnosed cancer in the United States. Because superficial bladder cancer (SBC) recurs in about 60% of cases, standard treatment involves tumor resection followed by intravesical therapies to prevent recurrence, as well as lifelong periodic cystoscopy. There is an urgent need for better intravesical therapies to prevent both the recurrence and progression of SBC. The Mammalian Target Of Rapamycin (mTOR) complex is upregulated in many bladder cancer tumors. We have targeted both the mTORc1 and mTORc2 complexes with drugs that inhibit both complexes. We used PP242 and a second inhibitor, OSI-027, which is currently in a phase I clinical trial for solid tumors (NCT00698243). Our in vitro model targets cell proliferation in three bladder cancer cell line (HT1376, T24 and UM-UC-3). Both drugs are effective in inhibiting the growth of bladder cancer cell lines with IC50 values between 0.6 and 18µM. In comparison with rapamycin, both drugs demonstrate effects on downstream targets of both the mTORc1 and mTORc2 pathways including 4EBP1 and pAkt. Receptor tyrosine kinases are another therapeutic target for bladder cancer. Lapatinib which targets EGFR and Her3, in combination with OSI-027 forms a highly synergistic treatment that inhibits bladder cancer cell line growth. Downstream molecular targets of the combination therapy, including the apoptosis markers PARP and caspase 3, were evaluated by Western blots. Our in vitro data suggests that a combination of dual mTOR inhibitors with RTK inhibitors may provide a novel effective therapeutic treatment for bladder cancer. Future studies of the in vivo efficacy of these drug combinations in a mouse model are planned. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 896. doi:1538-7445.AM2012-896

Abstract Biomarkers are lacking for identifying the switch of transforming growth factor-beta (TGF-β) from tumor-suppressing to tumor-promoting. Mutated p53 (mp53) has been suggested to switch TGF-β to a tumor promoter. However, we found that mp53 does not always promote the oncogenic role of TGF-β. Here, we show that endogenous mp53 knockdown enhanced cell migration and phosphorylation of ERK in DU145 prostate cancer cells. Further, ectopic expression of mp53 in p53-null PC-3 prostate cancer cells enhanced Smad-dependent signaling, but inhibited TGF-β-induced cell migration by downregulating activated ERK. Reactivation of ERK by the expression of its activator, MEK-1, restored TGF-β-induced cell migration. Since TGF-β is known to activate MAPK/ERK pathway through direct phosphorylation of adaptor protein ShcA and MAPK/ERK signaling is pivotal to tumor progression, we investigated whether ShcA contributed to mp53-induced ERK inhibition and the conversion of TGF-β's role during carcinogenesis. We found that mp53 expression led to decrease of phosphorylated p52ShcA/ERK levels and increase of phosphorylated Smad levels in a panel of mp53-expressing cancer cell lines, and in mammary glands and tumors from mp53 knock-in mice. By manipulating ShcA levels to regulate ERK and Smad signaling in human untransformed and cancer cell lines, we show that TGF-β's role in regulating anchorage-dependent and -independent growth, and migration, can be shifted between growth suppression and migration promotion. Thus, our results, for the first time, suggest that mp53 disrupts ShcA's role in balancing Smad-dependent and -independent signaling activity of TGF-β and that ShcA/ERK signaling is a major pathway regulating the tumor-promoting activity of TGF-β. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1069. doi:1538-7445.AM2012-1069

Abstract Metastatic solid tumors are aggressive and mostly drug resistant, leading to few treatment options and poor prognosis as seen with clear cell renal cell carcinoma (ccRCC) and triple-negative breast cancer (TNBC). Therefore, the identification of new therapeutic regimes for the treatment of metastatic disease is desirable. ccRCC and TNBC cell lines were treated with the HDAC inhibitor romidepsin and the methyltransferase inhibitor decitabine, two epigenetic modifying drugs approved by the U.S. Food and Drug Administration for the treatment of various hematologic malignancies. Cell proliferation analysis, flow cytometry, quantitative PCR, and immunoblotting techniques were used to evaluate the antitumor synergy of this drug combination and identify the reexpression of epigenetically silenced tumor suppressor genes. Combinatorial treatment of metastatic TNBC and stage IV ccRCC cell lines with romidepsin/decitabine leads to synergistic inhibition of cell growth and induction of apoptosis above levels of individual drug treatments alone. Synergistic reexpression of the tumor suppressor gene secreted frizzled-related protein one (sFRP1) was observed in combinatorial drug-treated groups. Silencing sFRP1 (short hairpin RNA) before combinatorial drug treatment showed that sFRP1 mediates the growth inhibitory and apoptotic activity of combined romidepsin/decitabine. Furthermore, addition of recombinant sFRP1 to ccRCC or TNBC cells inhibits cell growth in a dose-dependent manner through the induction of apoptosis, identifying that epigenetic silencing of sFRP1 contributes to renal and breast cancer cell survival. Combinatorial treatment with romidepsin and decitabine in drug resistant tumors is a promising treatment strategy. Moreover, recombinant sFRP1 may be a novel therapeutic strategy for cancers with suppressed sFRP1 expression. Mol Cancer Ther; 11(10); 2105–15. ©2012 AACR.

Abstract The Forkhead transcription factor, FoxO3a, is a known suppressor of primary tumor growth and is negatively regulated by growth factors via phosphorylation and mislocalization from the nucleus to the cytoplasm. Here we show for the first time that FoxO3a is nuclear in anaplastic thyroid carcinoma (ATC) and it transcriptionally upregulates cyclin A thereby promoting tumor growth in human ATC cells. Silencing FoxO3a in ATC cell lines leads to down-regulation of cyclin A mRNA and protein while over-expression of FoxO3a leads to upregulation of cyclin A protein. Transient co-transfection of cyclin A promoter linked to luciferase with FoxO3a leads to enhanced luciferase activity, which can be ablated when mutating the FoxO3a site on the cyclin A promoter. This combined data implicates an entirely novel function for FoxO3a in modulating cancer progression by promoting cell cycle progression and tumor growth. ATC is a poorly differentiated carcinoma with average survival upon diagnosis of 3–4 months with 99% lethality, notably the most aggressive and deadliest cancers known. This data also suggest that any therapies under development to inactivate FOXO3a may be effective at blocking tumor expansion. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1038. doi:10.1158/1538-7445.AM2011-1038

Abstract Renal cell carcinoma (RCC) accounts for 3% of all malignancies reported each year making it the sixth leading cause of cancer death in the United States. Within this year more than 50,000 individuals will be diagnosed with RCC and around 12,000 will die from this disease. Out of these RCCs the most frequently diagnosed form is clear cell renal cell carcinoma (ccRCC) which accounts for approximately 80% of all RCCs. We have previously identified through genomic profiling that loss of the type II and III TGFβ receptors in the progression of this disease lead to loss of TGFβ responsiveness and suggests a role for dysregulated TGFβ signaling in RCC progression and metastasis. Restoration of the TGFβ receptor type III (TβRIII) leads to apoptosis in RCC cell lines (Margulis et al. 2007) suggesting that re-expression of TβRIII is an attractive method for intervention of ccRCC. Recently we identified that loss of TβRIII is an early event in ccRCC and that this loss is not through epigenetic silencing but due to the loss of transcriptional regulation. The transcription factor GATA3 was identified to be a positive regulator of TβRIII expression through its actions on the proximal promoter of TβRIII. Through deletion analysis we have now identified a region within the proximal promoter that contains a number of putative transcription factor binding sites that are capable of negatively regulating the expression of TβRIII. We have identified that one of these transcription factors is over-expressed in ccRCC patient matched renal tissue samples and that silencing of this transcription factor through lentiviral shRNA, leads to a three fold induction of endogenous TβRIII in ccRCC cell lines. Furthermore, loss of this transcription factor in ccRCC cell lines leads to decreased cell proliferation when compared to non-target infected controls. Further evaluation of these putative negatively regulating transcription factors and their actions upon the proximal promoter of TβRIII are being analyzed utilizing EMSA and ChIP assays. These investigations will identify novel molecular targets that through their dysregulation will have the potential to up-regulate TβRIII in ccRCC inducing apoptosis within these cells. Together these findings will allow for a deeper molecular understanding of the events taking place in ccRCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 2173. doi:10.1158/1538-7445.AM2011-2173