STGC3 inhibits xenograft tumor growth of nasopharyngeal carcinoma cells by altering the expression of proteins associated with apoptosis

Abstract

STGC3 is a potential tumor suppressor that inhibits the growth of the nasopharyngeal carcinoma cell line CNE2; the expression of this protein is reduced in nasopharyngeal carcinoma compared with normal nasopharyngeal tissue. In this study, we investigated the tumor-suppressing activity of STGC3 in nude mice injected subcutaneously with Tet/pTRE-STGC3/CNE2 cells. STGC3 expression was induced by the intraperitoneal injection of doxycycline (Dox). The volume mean of Tet/pTRE-STGC3/CNE2+Dox xenografts was smaller than that of Tet/pTRE/CNE2+Dox xenografts. In addition, Tet/pTRE-STGC3/CNE2+Dox xenografts showed an increase in the percentage of apoptotic cells, a decrease in Bcl-2 protein expression and an increase in Bax protein expression. A proteomic approach was used to assess the protein expression profile associated with STGC3-mediated apoptosis. Western blotting confirmed the differential up-regulation of prohibitin seen in proteomic analysis. These results indicate that overexpression of STGC3 inhibits xenograft growth in nude mice by enhancing apoptotic cell death through altered expression of apoptosis-related proteins such as Bcl-2, Bax and prohibitin. These data contribute to our understanding of the function of STGC3 in human nasopharyngeal carcinoma and provide new clues for investigating other STGC3-associated tumors.

Sexual dimorphism of STGC3 tumor suppressor function in nasopharyngeal carcinoma CNE2 cells

“…Restoring the expression of STGC3 in CNE2 cells significantly inhibits its growth and proliferation in vitro and in vivo (He et al, 2008;Qiu et al, 2012). This indicates that STGC3 is a candidate tumor suppressor in NPC (He et al, 2004(He et al, , 2008Li et al, 2011;Qiu et al, 2012). Our experiments have also indicated that there is sexual dimorphism in the tumor inhibition effect of STGC3, with the gene's tumor suppressor effect being more prominent in female mice than in males.…”

“…Our previous research showed that the expression of STGC3 was diminished or even deleted in NPC cell lines and tissues. Restoring the expression of STGC3 in CNE2 cells significantly inhibits its growth and proliferation in vitro and in vivo (He et al, 2008;Qiu et al, 2012). This indicates that STGC3 is a candidate tumor suppressor in NPC (He et al, 2004(He et al, , 2008Li et al, 2011;Qiu et al, 2012).…”

LMP1 stimulates the transcription of eIF4E to promote the proliferation, migration and invasion of human nasopharyngeal carcinoma

“…CNE1 was established from a case of well‐differentiated NPC that was EBV‐negative (LMP1‐negative) , representing ~ 5% of the clinical NPC that is not associated with EBV infection. CNE2 was established from a case of poor‐differentiated NPC that was EBV‐positive (LMP1‐positive) , representing ~ 95% of the clinical NPC associated with EBV infection. Although LMP1 was positive during the early passage of CNE2, LMP1 levels were below the detection level in qRT‐PCR and western blot analysis .…”