Amplification and overexpression of vinculin are associated with increased tumour cell proliferation and progression in advanced prostate cancer

Abstract

Androgen withdrawal is the standard treatment for advanced prostate cancer. Although this therapy is initially effective, nearly all prostate cancers become refractory to it. Approximately 15% of these castration-resistant prostate cancers harbour a genomic amplification at 10q22. The aim of this study was to explore the structure of the 10q22 amplicon and to determine the major driving genes. Application of high-resolution array-CGH using the 244k Agilent microarrays to cell lines with 10q22 amplification allowed us to narrow down the common amplified region to a region of 5.8 megabases. We silenced each of the genes of this region by an RNAi screen in the prostate cancer cell lines PC-3 and 22Rv1. We selected genes with a significant growth reduction in the 10q22 amplified cell line PC-3, but not in the non-amplified 22Rv1 cells, as putative target genes of this amplicon. Immunohistochemical analysis of the protein expression of these candidate genes on a tissue microarray enriched for 10q22 amplified prostate cancers revealed vinculin as the most promising target of this amplicon. We found a strong association between vinculin gene amplification and overexpression (p < 0.001). Further analysis of 443 specimens from across all stages of prostate cancer progression showed that vinculin expression was highest in castration-resistant prostate cancers, but negative or very low in benign prostatic hyperplasia (p < 0.0001). Additionally, high tumour cell proliferation measured by Ki67 expression was significantly associated with high vinculin expression in prostate cancer (p < 0.0001). Our data suggest that vinculin is a major driving gene of the 10q22 amplification in prostate cancer and that vinculin overexpression might contribute to prostate cancer progression by enhancing tumour cell proliferation.

Vinculin promotes nuclear localization of TAZ to inhibit ECM stiffness-dependent differentiation into adipocytes

“…While cancer tissues have more rigid ECM than with normal tissues, YAP is activated and contributes to ECM stiffening in cancer-associated fibroblasts (Calvo et al, 2013). Vinculin is also involved in metastasis and malignancy of various cancers, including pancreatic, prostate and breast cancers (Rubashkin et al, 2014;Ruiz et al, 2011;Wang et al, 2012). Our results indicate that vinculin could regulate tumor progression through YAP/TAZ, in addition to through signals already known to be involved in tumorigenesis.…”

Characterization and Clinical Relevance of ALDHbright Populations in Prostate Cancer

“…The "progression TMA" contained single tissue cores from prostate cancers from all stages (25). The "castration-resistance TMA" has been recently described (26) and addresses the progression from hormone-na€ ve (HN) to lethal castration-resistant (CR) prostate cancer (27).…”

“…Immunohistochemical analyses were conducted according to standard indirect immunoperoxidase procedures as previously reported (25). Expression of ALDH1A1 in TMAs was assessed using a specific rabbit polyclonal antibody (ab51028, Abcam) at 1:200 (pretreatment: heat-mediated antigen retrieval at 100 C).…”

“…The 2 prostate TMAs used in this study were constructed as previously described (25). The "progression TMA" contained single tissue cores from prostate cancers from all stages (25).…”

Efficacy of Cetuximab in Metastatic Castration-Resistant Prostate Cancer Might Depend on EGFR and PTEN Expression: Results from a Phase II Trial (SAKK 08/07)

“…The staining intensity of all other markers was visually scored and stratified into 4 groups: negative (absence of staining), weak (weak but distinct immunoreactivity), moderate (between weak and strong), and strong (apparent even at small magnification; Â2.5 objective). A histoscore (H-score) was calculated as described earlier (12,7) by multiplying the staining intensity (0, 1, 2, or 3) with the percentage of positive cells, which leads to an H-score ranging from 0 to 300. In case of EGFR, only membranous staining was considered.…”