Expression of Gα12 predicts progression and prognosis of oral squamous cell carcinomas in Taiwan

BackgroundExpression of G12 is found to be associated with cancer cell proliferation, migration, invasion, and metastasis. MethodsThis study used immunohistochemistry to examine the expression of G12 protein in 100 specimens of oral squamous cell carcinoma (OSCC), 45 specimens of oral epithelial dysplasia (OED), and 36 specimens of normal oral mucosa (NOM). ResultsThe mean G12 labeling indices (LIs, defined as the percentage of positive cells in total cells) increased significantly from NOM (711%) through OED (21 +/- 20%) to OSCC samples (53 +/- 33%, P<0.001). The higher mean G12 LI was significantly associated with OSCCs with larger tumor size (P=0.003), positive lymph node metastasis (P=0.002), or more advanced clinical stages (P=0.003). Positive lymph node metastasis (P=0.039) and G12 LI>50% (P=0.009) were identified as independent unfavorable prognosis factors by multivariate analyses with Cox regression model. Moreover, Kaplan-Meier curve showed that OSCC patients with a G12 LI>50% had a significantly poorer cumulative survival than those with a G12 LI50% (log-rank test, P=0.009). ConclusionsOur results showed a stepwise and significant elevation in G12 protein expression from NOM through OED to OSCCs, suggesting that overexpression of G12 protein may be an early event in oral carcinogenesis and may play a pivotal role in oral cancer development. Moreover, the G12 protein can be a biomarker for prediction of the progression of OSCCs and the prognosis of patients with OSCC in Taiwan.