SDPR

Abstract: Hirschsprung disease (HSCR) is a well-known congenital digestive disease that originates due to the developmental disorder of neural crest cells. MiR-206 is kown to have a relationship with digestive malfunctions. Therefore, we investigated whether or not miR-206 was involved in the pathogenesis of HSCR. qRT-PCR and Western blot assays were used to detect the expression levels of miRNA and mRNAs, and proteins in case and control tissue samples and two cell lines (293T and SH-SY5Y). The functions of miR-206 in vitro were measured by transwell assay, CCK8 assay and flow cytometry. Finally, we conducted dual-luciferase reporter assay to verify the connections between miR-206 and the target mRNA SDPR. Down-regulation of miR-206 was found in HSCR case tissue samples compared with controls, which was validated to be connected with the increased level of mRNA and protein of SDPR by qRT-PCR and dual-luciferase reporter assay. Moreover, miR-206 suppressed the cell migration and proliferation and silencing of SDPR could rescue the extent of the suppressing effects by miR-206 inhibitor. The findings suggest that miR-206 may play a significant role in the pathogenesis of HSCR, as well as inhibiting the cell migration and proliferation by targeting SDPR in disease models.

Abstract: Caveolae are abundant membrane domain on the cell surface of many mammalian cell types and are implicated in a wide range of physiological processes. The caveolae structural protein caveolin-1 is often mutated or deregulated in cancer, and cavin family protein serum deprivation response factor-related gene product that binds to C-kinase (SRBC) has been found to be epigenetically inactivated in lung, breast, and gastric cancer. Both caveolin-1 and SRBC have been proposed to function as tumor suppressors. Polymerase 1 and transcript release factor (PTRF) is the essential component for caveolae formation. The regulation of PTRF expression in cancer has not been characterized. We report here that the cavin family protein PTRF, SRBC and serum deprivation response protein were down regulated in breast cancer cell lines and breast tumor tissue. We further show that down-regulation of PTRF in breast cancer cells was associated with the promoter methylation. As caveolin-1 and cavin family proteins are required for caveolae formation and function, the reported tumor suppression function of caveolin-1 and SRBC may be due to the deregulation of caveolae and its down-stream signaling. Thus, the caveolae is a potential therapeutic target and the expression of cavin family proteins could be a useful prognostic indicator of breast cancer progression.

Abstract: Metastatic dissemination of breast cancer cells represents a significant clinical obstacle to curative therapy. The loss of function of metastasis suppressor genes is a major rate-limiting step in breast cancer progression that prevents the formation of new colonies at distal sites. However, the discovery of new metastasis suppressor genes in breast cancer using genomic efforts has been slow, potentially due to their primary regulation by epigenetic mechanisms. Here, we report the use of model cell lines with the same genetic lineage for the identification of a novel metastasis suppressor gene, serum deprivation response (SDPR), localized to 2q32-33, a region reported to be associated with significant loss of heterozygosity in breast cancer. In silico metaanalysis of publicly available gene expression datasets suggests that the loss of expression of SDPR correlates with significantly reduced distant-metastasis-free and relapse-free survival of breast cancer patients who underwent therapy. Furthermore, we found that stable SDPR overexpression in highly metastatic breast cancer model cell lines inhibited prosurvival pathways, shifted the balance of Bcl-2 family proteins in favor of apoptosis, and decreased migration and intravasation/extravasation potential, with a corresponding drastic suppression of metastatic nodule formation in the lungs of NOD/SCID mice. Moreover, SDPR expression is silenced by promoter DNA methylation, and as such it exemplifies epigenetic regulation of metastatic breast cancer progression. These observations highlight SDPR as a potential prognostic biomarker and a target for future therapeutic applications.