An Examination of the Association between FOXA1 Staining Level and Biochemical Recurrence following Salvage Radiation Therapy for Recurrent Prostate Cancer.

BACKGROUND: Standardly collected clinical and pathological patient information has demonstrated only moderate ability to predict risk of biochemical recurrence (BCR) of prostate cancer in men undergoing salvage radiation therapy (SRT) for a rising PSA after radical prostatectomy (RP). Although elevated FOXA1 staining has been associated with poor patient outcomes following RP, it has not been studied in the specific setting of SRT after RP. The aim of this study was to evaluate the association between FOXA1 staining level and BCR after SRT for recurrent prostate cancer. METHODS: A total of 141 men who underwent SRT at our institution were included. FOXA1 staining levels in primary tumor samples were detected using immunohistochemistry. FOXA1 staining percentage and intensity were measured and multiplied together to obtain a FOXA1 H-score (range 0-12) which was our primary staining measure. P-values ≤ 0.0056 were considered as statistically significant after applying a Bonferroni correction for multiple comparisons. RESULTS: There was not a significant association between FOXA1 H-score and risk of BCR when considering H-score as an ordinal variable or as a categorical variable (all P ≥ 0.090). Similarly, no significant associations with BCR were observed for FOXA1 staining percentage or staining intensity (all P ≥ 0.14). CONCLUSIONS: FOXA1 staining level does not appear to have a major impact on risk of BCR after SRT.

The combination of an mTORc1/TORc2 inhibitor with lapatinib is synergistic in bladder cancer in vitro.

OBJECTIVE: To examine the ability of dual mTORc1/c2 inhibitors in conjunction with lapatinib to function in a synergistic manner to inhibit cell proliferation and anchorage-independent growth in bladder cancer cell lines. MATERIALS AND METHODS: We examined patient tumor samples for overexpression of pS6, p4EBP1, pAkt, and phosphorylated epidermal growth factor receptor (pEGFR) using a tissue microarray containing 84 cases. Three bladder cancer cell lines, T24, HT1376, and UM-UC-3, were analyzed for cell proliferation after treatment with mTORc1/c2 inhibitors OSI-027 or PP242. Western blots were used to verify that the drugs were inhibiting phosphorylation of target proteins within the mTOR pathway, and they were compared with rapamycin inhibition. We also analyzed cell proliferation and anchorage-independent growth after treatment with OSI-027 and lapatinib in combination. PARP cleavage and autophagic flux were measured by examining levels of LC3B and p62 by western blotting. RESULTS: Tumor samples show increased expression of pEGFR (38% vs. 8%) and HER2 (38% vs. 4%) and decreased expression of pAkt S473 (7.5% vs. 29%) and pAkt T308 (50% vs. 84%) relative to normal tissue. Significant differences between normal and tumor samples for staining with pEGFR (P = 0.0188), HER 2 (P = 0.0017), pATK S473 (P = 0.0128), and pAkt T308 (P = 0.0015) is observed. Expression of proteins within the EGFR/HER2 pathway or within the mTOR pathway is correlated. No correlation was found between staining and tumor stage. OSI-027 and PP242 diminish cell proliferation in all 3 cell lines with IC50 values ranging from 0.63 to 17.95µM. Both drugs inhibit phosphorylation of both mTORc1 and mTORc2 pathway components. OSI-027 and lapatinib inhibit cell proliferation and anchorage-independent growth in a synergistic manner. One cell line exhibited apoptosis in response to combination drug treatment, whereas the other 2 cell lines have increased levels of autophagy indicative of resistance to apoptosis. CONCLUSIONS: The combination of OSI-027 and lapatinib results in antitumor synergy and further exploration of this combination should be undertaken.

Oncogenic K-ras promotes early carcinogenesis in the mouse proximal colon.

Oncogenic K-ras mutations are frequently observed in colon cancers and contribute to transformed growth. Oncogenic K-ras is detected in aberrant crypt foci (ACF), precancerous colonic lesions, demonstrating that acquisition of a K-ras mutation is an early event in colon carcinogenesis. Here, we investigate the role of oncogenic K-ras in neoplastic initiation and progression. Transgenic mice in which an oncogenic K-ras(G12D) allele is activated in the colonic epithelium by sporadic recombination (K-rasLA2 mice) develop spontaneous ACF that are morphologically indistinguishable from those induced by the colon carcinogen azoxymethane (AOM). Similar neoplastic changes involving the entire colon are induced in transgenic mice constitutively expressing K-ras(G12D) throughout the colon (LSL-K-ras(G12D)/Villin-Cre mice). However, the biochemistry and fate of K-ras-induced lesions differ depending upon their location within the colon in these mice. In the proximal colon, K-ras(G12D) induces increased expression of procarcinogenic protein kinase C beta II (PKC beta II), activation of the MEK/ERK signaling axis and increased epithelial cell proliferation. In contrast, in the distal colon, K-ras(G12D) inhibits expression of procarcinogenic PKC beta II and induces apoptosis. Treatment of K-rasLA2 mice with AOM leads to neoplastic progression of small ACF to large, dysplastic microadenomas in the proximal, but not the distal colon. Thus, oncogenic K-ras functions differently in the proximal and distal colon of mice, inducing ACF capable of neoplastic progression in the proximal colon, and ACF with little or no potential for progression in the distal colon. Our data indicate that acquisition of a K-ras mutation is an initiating neoplastic event in proximal colon cancer development in mice.

Secreted frizzled-related protein 1 loss contributes to tumor phenotype of clear cell renal cell carcinoma.

PURPOSE: Incidence and mortality rates for renal cell carcinoma (RCC) have been rising for decades. Unfortunately, the molecular events that support RCC carcinogenesis remain poorly understood. In an effort to gain a better understanding of signaling events in clear cell RCC (cRCC), we investigated the antitumor activity of secreted frizzled-related protein 1 (sFRP1), a negative regulator of Wnt signaling. EXPERIMENTAL DESIGN: Genomic profiling of cRCC tumors and patient-matched normal tissues was done and confirmed using quantitative PCR and immunohistochemistry. Methylation-specific PCR was done on patient samples to evaluate the mechanism responsible for sFRP1 loss. sFRP1 expression was restored in cRCC cells and the effects on tumor phenotype were characterized. RESULTS: Genomic profiling, quantitative PCR, and immunohistochemistry indicated that loss of sFRP1 occurred in cRCC and papillary RCC patient tissues. Twelve Wnt-regulated genes were up-regulated in cRCC tissues, including c-myc and cyclin D1, potentiators of cell proliferation and survival. Methylation of the sFRP1 gene was one mechanism identified for attenuation of sFRP1 mRNA. Stable reexpression of sFRP1 in cRCC cells resulted in decreased expression of Wnt target genes, decreased growth in cell culture, inhibition of anchorage-independent growth, and decreased tumor growth in athymic nude mice. CONCLUSIONS: To our knowledge, this is the first report to show that stable restoration of sFRP1 expression in cRCC cells attenuates the cRCC tumor phenotype. Our data support a role for sFRP1 as a tumor suppressor in cRCC and that perhaps loss of sFRP1 is an early, aberrant molecular event in renal cell carcinogenesis.