Oral squamous cell carcinoma (OSCC) has a propensity to spread to the cervical lymph nodes (LN). The presence of cervical LN metastases severely impacts patient survival, whereby the two-year survival for oral cancer patients with involved LN is ~30% compared to over 80% in patients with non-involved LN. Elucidation of key molecular mechanisms underlying OSCC metastasis may afford an opportunity to target specific genes, to prevent the spread of OSCC and to improve patient survival. In this study, we demonstrated that expression of the heterotrimeric G-protein alpha-12 (Gα12) is highly up-regulated in primary tumors and LN of OSCC patients, as assessed by quantitative polymerase chain reaction (qPCR) and immunohistochemistry (IHC). We also found that exogenous expression of the constitutively activated-form of Gα12 promoted cell migration and invasion in OSCC cell lines. Correspondingly, inhibition of Gα12 expression by shRNA consistently inhibited OSCC cell migration and invasion in vitro. Further, the inhibition of G12 signaling by regulator of G-protein signaling (RGS) inhibited Gα12-mediated RhoA activation, which in turn resulted in reduced LN metastases in a tongue-orthotopic xenograft mouse model of oral cancer. This study provides a rationale for future development and evaluation of drug candidates targeting Gα12-related pathways for metastasis prevention.
Matched MeSH terms: GTP-Binding Protein alpha Subunits, G12-G13/antagonists & inhibitors; GTP-Binding Protein alpha Subunits, G12-G13/genetics; GTP-Binding Protein alpha Subunits, G12-G13/metabolism*
Introduction: Oral squamous cell carcinoma (OSCC) is a major health problem worldwide. The overall survival rate remains at 50% despite numerous studies and various treatment modalities in OSCC. The presence of lymph node metastasis in OSCC is well established as an independent prognostic factor. This present study aims to investigate the association of four tumour antigens; FJX-1, GNα12, IFITM3 and MAGED4B with the sociodemographic and clinicopathological parameters of OSCC. The potential use of these markers as a prognostic indicator of patient sur-vival and lymph node metastasis in OSCC was explored. Methods: 35 cases of OSCC with available formalin-fixed paraffin-embedded (FFPE) specimens involving the tongue, buccal mucosa, gingiva, alveolus and floor of mouth were evaluated by immunohistochemistry for FJX-1, GNA12, IFITM3 and MAGED4B expression. Assessment of the expression of these tumour antigens was based on the cellular sub-site, intensity and percentage of staining in the OSCC samples. Results: The expression of all four tumour markers were expressed in all samples (n=35) but none statistically associated with any clinicopathological or socio-demographic parameters. Survival analysis using Kaplan-Meier test showed high expression of GNA12, IFITM3 and MAGED4B individually with poor prognosis in OSCC patients. A combination of markers, GNA12 and MAGED4B demonstrated a significant association with pa-tient survival in OSCC (p=0.014). Multivariate analysis after adjustment for selected socio-demographic factors (age, gender, risk habits and sub-sites of the oral cavity) revealed that high expression of both MAGED4B and GNA12 remained as an independent prognostic factor for poor prognosis in OSCC (HRR =5.231, 95% CI 1.601,17.084; p=0.006). Conclusion: We concluded that high combined expression of both marker (Gα12 and mAGED4B) might be used as an independent prognostic indicator in OSCC.
Matched MeSH terms: GTP-Binding Protein alpha Subunits, G12-G13