Characterization of the gene encoding pinin/DRS/memA and evidence for its potential tumor suppressor function

Abstract

Several cell adhesion-related proteins have been shown to act as tumor-suppressors (TS) in the neoplastic progression of epithelial-derived tumors. Pinin/DRS/memA was ®rst identi®ed in our laboratory and it was shown to be a cell adhesion-related molecule. Our previous study demonstrated that restoration of pinin expression in transformed cells not only positively in¯uenced cellular adhesive properties but also reversed the transformed phenotype to more epithelial-like. Here, we show by FISH analysis that the gene locus for pinin is within 14q13. The alignment of the pinin gene with STS markers localized the gene to the previously identi®ed TS locus D14S75-D14S288. Northern analyses revealed diminished pinin mRNA in renal cell carcinomas (RCC) and certain cancer cell lines. Immunohistochemical examination of tumor samples demonstrated absent or greatly reduced pinin in transitional cell carcinoma (TCC) and RCC tumors. TCC-derived J82 cells as well as EcR-293 cells transfected with full-length pinin cDNA demonstrated inhibition of anchorage-independent growth of cells in soft agar. Furthermore, methylation analyses revealed that aberrant methylation of pinin CpG islands was correlated with decreased/absent pinin expression in a subset of tumor tissues. These data lend signi®cant support to the hypothesis that pinin/DRS/memA may act as a tumor suppressor in certain types of cancers.

Role of Pinin in neural crest, dorsal dermis, and axial skeleton development and its involvement in the regulation of Tcf/Lef activity in mice

“…Down-regulation of PNN by shRNA causes cells to become less adherent and more migratory and leads to down-regulation of several key adhesion molecules, including desmoplakin, ZO-1, and E-cadherin, which is a hallmark of neoplastic transformation (Joo et al, 2005). Consistently, PNN has been suggested to function as a tumor suppressor by studies demonstrating that PNN expression was significantly reduced in several cancer cell lines, and that exogenous PNN expression in transitional cell carcinoma-derived J82 cells led to the inhibition of anchorage-independent growth (Shi et al, 2000a). Furthermore, PNN overexpressing HEK 293 cells exhibited significant G1-S delay (Shi et al, 2001), suggesting that PNN may affect cell proliferation, and that its tumor suppressor function may not be restricted to stabilization of cell adhesion.…”

Change in gene expression subsequent to induction of Pnn/DRS/memA: increase in p21cip1/waf1

“…We demonstrated that transformed cells (293 cells), which exhibit anchorageindependent growth, became anchorage-dependent upon expression of Pnn (Shi et al, 2000a). We also demonstrated that p21 cip1/waf1 levels are upregulated subsequent to increasing Pnn expression.…”

“…Diminished PNN mRNA and protein levels have been documented in transitional cell and renal cell carcinomas (Shi et al, 2000a). Restoration of Pnn expression in transformed cells not only positively in¯uenced cellular adhesive properties, but also reversed the transformed phenotype of anchorageindependent growth (Ouyang and Sugrue, 1996;Shi et al, 2000a). The potential involvement of Pnn in cancer development was also suggested by aberrant expression of Pnn/DRS/memA in melanoma (Degen et al, 1999).…”

“…The PNN gene is located within the TS locus 14q13 (D14575-D145288) (Shi et al, 2000a). Diminished PNN mRNA and protein levels have been documented in transitional cell and renal cell carcinomas (Shi et al, 2000a). Restoration of Pnn expression in transformed cells not only positively in¯uenced cellular adhesive properties, but also reversed the transformed phenotype of anchorageindependent growth (Ouyang and Sugrue, 1996;Shi et al, 2000a).…”

“…Several studies have indicated a role for PNN at sites of cell adhesion, as well as within the nucleus (Brandner et al, 1997;Ouyang, 1999;Ouyang andSugrue, 1992, 1996). The PNN gene is located within the TS locus 14q13 (D14575-D145288) (Shi et al, 2000a). Diminished PNN mRNA and protein levels have been documented in transitional cell and renal cell carcinomas (Shi et al, 2000a).…”