Citations

AbstractSTAT3 regulates cell growth by up-regulating downstream targets, such as Myc. The frequency of phosphorylated STAT3 (pSTAT3) and Myc expression and their prognostic relevance is unknown within diffuse large B-cell lymphoma (DLBCL) germinal center B-cell (GCB) and non-GCB subtypes. pSTAT3 and Myc were studied by immunohistochemistry (IHC) on tumors from 40 DLBCL patients uniformly treated on a clinical trial of epratuzumab/rituximab-CHOP. A total of 35% of cases were pSTAT3-positive, and pSTAT3 positivity was more frequent in the non-GCB (P = .06) type but did not correlate with event-free survival (EFS). Myc expression was observed in 50% of cases and was more frequent in non-GCB type (P = .07). Myc-positive cases had inferior EFS in all patients, including the GCB and pSTAT3-positive cases, were more likely to express Myc (P = .06). Myc translocations involving the major breakpoint regions were found in 10% (3 of 29) of cases, and all 3 cases were GCB and had an inferior EFS (P = .09). pSTAT3, but not Myc expression, was correlated with elevated pretreatment serum cytokines, such as IL-10 (P = .05), G-CSF (P = .03), and TNF-α (P = .04). pSTAT3 IHC in DLBCL tumors has the potential to identify patients for STAT3 pathway–directed therapy; Myc IHC is a potential marker for inferior EFS in GCB patients.

Abstract Purpose: Pancreatic adenocarcinoma is among the most lethal forms of all malignancies. While significant research has implicated multiple genes in disease pathogenesis, identification of therapeutic leads has been difficult. The majority of currently available therapies provide only marginal benefit. To address this issue, our goal was to assess global somatic events across multiple pancreatic tumors by using next-generation sequencing technologies (NGS). Experimental Design: We performed whole genome sequencing (WGS) on paired tumor and normal samples from 3 pancreatic adenocarcinoma patients. Additionally, we performed whole transcriptome sequencing (WTS) on 2 of these patients’ tumors for which tumor RNA was available. Results: We generated on average 132 billion mappable bases across all patients using WGS, and identified 140 somatic coding events including point mutations, insertion/deletions, and chromosomal copy number variants. Data from WGS and WTS were integrated and analyzed to identify the most heavily affected pancreatic cancer pathways across all patients. The KRAS signaling pathway was identified as the most significant map. Unbiased global pathway analysis was also performed to identify processes that may be impacted. Consistent with the previous analysis, the most significant pathway from this analysis is also KRAS signaling. This integrated analysis specifically identifies heavily affected pathways in pancreatic cancer and pinpoints genes and processes that may be considered as targets for more effective therapies. Conclusions: While sequencing of additional patients is necessary to strengthen selection of key pathways, we demonstrate the utility of using NGS to understand the processes driving pancreatic adenocarcinoma so that standardized treatments for patients may be improved. 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 5104. doi:1538-7445.AM2012-5104

Abstract Adrenocortical carcinoma (ACC) is an aggressive cancer with a 5-year survival rate of 20-30%. Mitotane is the only approved drug for the treatment of patients with ACC. It often carries significant toxicities which result in the discontinuation of treatment. There are no approved second line therapies. The increased incidence of ACC in the cancer predisposition syndrome, Li-Fraumeni, suggests the involvement of the p53 pathway in ACC pathogenesis. Our analysis of the gene expression profiles of 19 ACC samples identified dysregulation of the G2/M transition and the activity of the p53 modulator, MDM2 as important in ACC pathogenesis. Polo-like kinase-1 (PLK1) is involved in the G2/M transition and acts to promote MDM2 activity through its phosphorylation. We observed that PLK1 inhibition by siRNA results in up to a 70% reduction in viability in the ACC cell lines SW-13 and H295R. Therefore, we studied PLK1 inhibition as a potential therapeutic strategy. We used the small molecule inhibitor, BI-2536, to inhibit PLK1 function in SW-13 and H295R. Drug-dose response curves demonstrated that both cell lines are sensitive to pharmacological inhibition of PLK1 (IC50 doses of 0.0094815 μM and 0.062805 μM for SW-13 and H295R, respectively.) Murine xenograft studies demonstrated that BI-2536 resulted in a statistically significant reduction in tumor growth in SW-13 but not H295R. Examination of p53 protein levels in the presence of the drug showed a dose-dependent reduction in p53 levels in SW-13, which carries a homozygous p53 mutation. The same was not true in H295R, which is p53 wild-type. To test the hypothesis that BI-2536 was decreasing mutant p53 levels by promoting its proteasomal degradation, both cell lines were treated with previously determined inhibitory concentrations of BI-2536, either alone or in combination with the proteasome inhibitor, MG132. Western blot analysis showed recovery of p53 protein when cells were concomitantly treated with MG132, supporting a role for BI-2536 as a regulator of proteasomal degradation. Both ACC cell lines are relatively insensitive to MDM2 inhibition by nutlin-3 (NCI60 GI50 values range from ∼4 uM to ∼2 uM versus ACC cell lines @13-15uM), possibly because PLK1 stimulates MDM2 and renders nutlin-3 ineffective. We therefore assessed the ability of BI-2536 to sensitize ACC cell lines to the effects of the MDM2 inhibitor. BI-2636 did show synergy with nutlin-3, shifting the IC50 in SW-13 from 19.78 μM to 6.45 μM and from 12.75 μM to 2.84 μM in H295R. These results demonstrate that inhibition of PLK1 alone or in combination with an MDM2 inhibitor warrants further investigation as a treatment for patients with ACC. Cells with mutant p53 are more sensitive to the growth inhibitory effects of BI-2536. In the context of wild-type p53, the combined inhibition of both PLK1 and MDM2 results in loss of viability. Further clinical development of PLK1 as a target should take p53 mutation status into account. 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 978. doi:1538-7445.AM2012-978

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.