Pathway Signature and Cellular Differentiation in Clear Cell Renal Cell Carcinoma

BACKGROUND: Clear cell renal cell carcinoma (ccRCC) is the most common kidney cancer. The purpose of this study is to define a biological pathway signature and a cellular differentiation program in ccRCC. METHODOLOGY: We performed gene expression profiling of early-stage ccRCC and patient-matched normal renal tissue using Affymetrix HG-U133a and HG-U133b GeneChips combined with a comprehensive bioinformatic analyses, including pathway analysis. The results were validated by real time PCR and IHC on two independent sample sets. Cellular differentiation experiments were performed on ccRCC cell lines and their matched normal renal epithelial cells, in differentiation media, to determine their mesenchymal differentiation potential. PRINCIPAL FINDINGS: We identified a unique pathway signature with three major biological alterations-loss of normal renal function, down-regulated metabolism, and immune activation-which revealed an adipogenic gene expression signature linked to the hallmark lipid-laden clear cell morphology of ccRCC. Culturing normal renal and ccRCC cells in differentiation media showed that only ccRCC cells were induced to undergo adipogenic and, surprisingly, osteogenic differentiation. A gene expression signature consistent with epithelial mesenchymal transition (EMT) was identified for ccRCC. We revealed significant down-regulation of four developmental transcription factors (GATA3, TFCP2L1, TFAP2B, DMRT2) that are important for normal renal development. CONCLUSIONS: ccRCC is characterized by a lack of epithelial differentiation, mesenchymal/adipogenic transdifferentiation, and pluripotent mesenchymal stem cell-like differentiation capacity in vitro. We suggest that down-regulation of developmental transcription factors may mediate the aberrant differentiation in ccRCC. We propose a model in which normal renal epithelial cells undergo dedifferentiation, EMT, and adipogenic transdifferentiation, resulting in ccRCC. Because ccRCC cells grown in adipogenic media regain the characteristic ccRCC phenotype, we have identified a new in vitro ccRCC cell model more resembling ccRCC tumor morphology

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

Representative immunostaining showing examples of prostate tumors with (A) negative staining intensity, (B) weak staining intensity, and (C) moderate staining intensity.

<p>Representative immunostaining showing examples of prostate tumors with (A) negative staining intensity, (B) weak staining intensity, and (C) moderate staining intensity.</p

Association between FOXA1 staining level and biochemical recurrence following salvage radiation therapy.

<p>Association between FOXA1 staining level and biochemical recurrence following salvage radiation therapy.</p

Representative immunostaining showing examples of prostate tumors with (A) 0–25% staining percentage, (B) 26–50% staining percentage, (C) 51–75% staining percentage, and (D) 76–100% staining percentage.

<p>Representative immunostaining showing examples of prostate tumors with (A) 0–25% staining percentage, (B) 26–50% staining percentage, (C) 51–75% staining percentage, and (D) 76–100% staining percentage.</p

Summary of FOXA1 staining.

<p>Summary of FOXA1 staining.</p