P1-02-03: The Reciprocal Roles of E-Cadherin and ZEB1 Demonstrate the Mesenchymal-Epithelial Transition as a Primary Characteristic of Inflammatory Breast Cancer

Background: Inflammatory breast cancer (IBC) is a rare but very aggressive form of breast cancer. IBC is characterized by nests of tightly aggregated cells, defined as tumor emboli, that exhibit characteristics of cancer stem cells (CSCs). IBC tumor emboli express E-cadherin which is required to maintain their integrity and our recent evidence demonstrates that expression of E-cadherin by tumor emboli is associated with lack of ZEB1 expression, a transcriptional repressor of E-cadherin. This is at odds with the current hypothesis that metastatic progression is associated with the process of epithelial mesenchymal transition (EMT), with loss of E-cadherin and gain of transcription factors including ZEB1, acquisition of CSC characteristics and enhanced invasive capabilities.

Materials and Methods: shRNA knockdown and over-expression methods, real time PCR arrays, western blotting, and in vitro assays to evaluate proliferation, invasion, growth in soft agar and clonogenicity and in vivo animal studies were used.

Results: Expression of E-cadherin was reduced by shRNA and ZEB1 was expressed in SUM149 IBC tumor cells. Numerous EMT-related genes were upregulated with loss of E-cadherin and gain of ZEB1, including N-cadherin and vimentin. However, there were marginal differences in the in vitro parameters of proliferation, Matrigel invasion and anchorage independent growth in soft agar between SUM149-shECad or SUM149-ZEB1 clones and their respective vector control cells. The loss of E-cadherin and gain of ZEB1 altered the morphology of SUM149 cells when cultured under low adherence conditions permissive for the enrichment of CSC, exhibiting a reversion in grape-like morphology to more well defined spheres, which was accompanied by increased clonogenicity in both SUM149-shECad and SUM149-ZEB1 cells. The loss of E-cadherin and the gain of ZEB1 significantly inhibited tumor growth of cells injected in the mammary fat pad of NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ mice. Tumor volume at 56 days for E-cadherin vector control cells was 771.9 mm3 +/− 185.6 compared to shECadherin tumors, which was 13.6 mm3 +/− 7.2. Tumor volume of ZEB1 vector control tumors was 346.1 mm3 +/− 96 compared to volume of ZEB1 expressing tumors, which was 21.5 mm3 +/− 7.2.Conclusions: E-cadherin with lack of ZEB1 expression in IBC is consistent with a mesenchymal-epithelial transition (MET), consistent with the retention of the epithelial phenotype while maintaining a program of rapid metastasis and colonization of lymph nodes and distant organ sites. Furthermore, we demonstrate that the E-cadherin-ZEB1 axis is critical for the in vivo growth of IBC tumor cells. Although SUM149 cells are fully capable of undergoing an EMT process, which is under negative regulation by E-cadherin, the process of EMT does not drive in vivo tumor growth in IBC.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P1-02-03.

Prognostic factors for stage IV gastric cancer

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Background: In general, the most significant prognostic factor for gastric cancer is tumor stage. In a patient with stage IV gastric cancer, other prognostic factors would be helpful to guide appropriate therapy and to avoid unnecessary suffering as well as fruitless and expensive therapy.

Methods: Data of all patients with gastric cancer managed at the Department of Surgery of The University of Hong Kong are entered prospectively into a computer database. Between January 1996 and December 2007, 1,109 patients who have not received prior treatment for their gastric cancer are included in the present study. Factors correlated with tumor stage as well as factors associated with survival are studied with univariate analysis. Significant factors are then subjected to multivariate analysis. In patients with stage IV disease, significant factors associated with survival are then studied with univariate and multivariate Cox regression analysis.

Results: 1,109 patients with age of 66 ± 14 years were included. There was a male predominance (M:F = 705:404). 18.1%, 10.3%, 28.3%, and 43.2% have stage I, II, III, and IV diseases, respectively. Spearman's rank correlation analysis identified haemoglobin, lymphocyte/WCC ratio (LWR), platelet count, albumin, CEA, CA19-9, and C-reactive protein (CRP) to be significantly correlated with tumor stage. Multivariate analysis identified LWR, platelet count, albumin, CA 19-9 and CRP as independent factors associated with tumor stage. On the other hand, CA19-9, CRP, LWR and tumor stage were found to be independent prognostic factors associated with overall survival. Among the group of patients with stage IV disease, ECOG status (OR 1.265, 95% CI 1.025 – 1.562), CA 19-9 (OR 1.0, 95% CI 1.0 – 1.0), CRP (OR 1.050, 95% CI 1.021 – 1.081) as well as LWR (OR 0.076, 95% CI 0.011 – 0.552) were found to be independent prognostic factors for survival.

Conclusions: Within the group of patients with stage IV gastric cancer, ECOG status, lymphocyte/ WCC ratio, serum CA19.9 and C-reactive protein level were found to be independent prognostic factors for survival.

No significant financial relationships to disclose.

Abstract P6-04-13: Gene and microRNA Signatures of the Mesenchymal Epithelial Transition in Pre-Clinical Models of Inflammatory Breast Cancer

Inflammatory breast cancer (IBC) is the most aggressive form of locally advanced breast cancer The pathological hallmark of IBC is lymphovasculogenesis resulting in the invasion of tightly adhered cells, defined as tumor emboli, into lymphovascular spaces of the dermis. IBC tumor emboli have been reported to over-express the glycoprotein E-cadherin, which is at odds with the current hypothesis that tumors with a metastatic phenotype lose E-cadherin, and gain expression of specific transcription factors and microRNAs (miRs) that mediate the process of epithelial mesenchymal transition (EMT). Immunohistochemical staining confirms the presence of E-cadherin on tumor emboli in IBC patient tissues as well as in Mary-X tumor xenografts, which is the only model to recapitulate tumor emboli in vivo. Using unbiased global transcriptional profiling, microRNA microarrays, real time PCR, Western blot validation, immunohistochemistry, immunofluorescence and confocal microscopy, we found that IBC cell lines, and Mary-X tumor emboli from xenografts had significantly elevated expression of genes and their corresponding proteins that collectively mediate tight homotypic cell:cell aggregation, including CDH1 which encodes for E-cadherin, DSC2, which encodes for Desmocollin 2 and JUP/CTNNG1, which encodes for junctional plakoglobin/gamma catenin. Regardless of molecular subtype, IBC cell lines and Mary-X tumor spheroids lacked detectable mRNA or protein for zinc finger E-box binding homeobox 1 gene, ZEB1, with very low levels of ZEB2 gene expression. The expression of CDH1, loss of ZEB1 and low gene expression of ZEB2 by IBC cell lines and Mary-X tumor spheroids was associated with increased expression of specific families of microRNAs including the miR 200 family known to be transcriptional regulators of E-cadherin. In contrast to lack of ZEB1 expression, IBC cell lines expressed either one or all of the SNAI1, SNAI2 and TWIST1 genes, which encode for transcription factors that have been associated with the process of EMT. IBC cell lines that contained ZEB1 cDNA lacked expression of CDH1 and did not produce E-cadherin protein, however the IBC/ZEB1 clones exhibited little difference in their ability to invade across an artificial Matrigel membrane compared to either vector control cells or the parental IBC cells. Taken together, the present observations suggest that pre-clinical models of IBC have distinct gene and microRNA signatures characterized by expression of genes and miRs that collectively support the persistence of compact tightly aggregated tumor cells within IBC tumor emboli, while maintaining an invasive and metastatic phenotype, suggesting that IBC tumor emboli display characteristics of the process of mesenchymal-epithelial transition (MET). Supported in part by the American Airlines-Komen For the Cure Foundation Promise Grant KGO81287 (FMR, MC) and The State of Texas Fund for Rare and Aggressive Breast Cancer (FMR, SK).

Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P6-04-13.

Imaging protein statistical substate occupancy in a spectrum-function phase space

Hemeprotein ligand rebinding studies reveal varying IR absorbance and rebinding functions across a cryogenic ensemble. Since IR-active vibrations and rebinding barriers couple to structural coordinates, spectral and functional heterogeneity arise from conformational heterogeneity. Modeling rebinding data as a spectrally resolved superposition of first-order rate processes and employing maximum entropy regularization, protein heterogeneity is imaged as an ensemble occupancy of a spectrum-function phase space. Results from myoglobin rebinding carbon monoxide are discussed.

Phase II trial of GTX chemotherapy in metastatic pancreatic cancer

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Background: Preclinical studies suggest synergy between gemcitabine (G), docetaxel (T) and capecitabine (X). This GTX regimen was designed to inhibit MEK-ERK phosphorylation and increase BAX and BAK and also decrease BCL-2 in pancreatic cancer cell lines. Based on these findings, we pursued a prospective clinical trial evaluating the activity of GTX in previously untreated patients with metastatic pancreatic cancer. Methods: Patients with histologically confirmed metastatic adenocarcinoma of the pancreas, median age 60, 63% male, ECOG PS 0–2, received capecitabine 1500mg/m2/day total orally in divided doses, days 1 thru 14, gemcitabine 750mg/m2 IV over 75 minutes followed by docetaxel 30mg/m2 IV on days 4 and 11 on a 21 day cycle. Scans were completed every 9 to 10 weeks to assess for tumor response by RECIST criteria. Treatment was continued until evidence of disease progression, intolerable toxicity, surgery or a delay in treatment greater than 6 weeks. The primary endpoint was response rate. Secondary endpoints were overall survival (OS) measured as time from start of GTX to death, time to treatment failure (TTF) measured as time from start of GTX to disease progression or other reason for a halt in therapy. Results: Forty-three patients were enrolled at two centers between May 2004 and January 2007. Forty-one patients were eligible for assessment by intent to treat analysis. 35 patients (85%) had liver metastases. 9 patients (21.9%) had partial responses and 17 patients (41.5%) had stable disease. The one year survival rate was 56%. Two year survival rate was 14.6%. The median OS was 14.5 months. The median TTF was 6.9 months. Grade 3 and 4 toxicities included leukopenia (31.6%), neutropenia (29.2%), thrombocytopenia (12.2%), infection (12.5%), and mucositis (7.5%). Conclusions: The combination of gemcitabine, docetaxel, and capecitabine has activity in metastatic pancreatic cancer with a median survival over 1 year. A randomized phase III trial is in planning.

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