Methylation of STK11 promoter is a risk factor for tumor stage and survival in clear cell renal cell carcinoma.

Inactivation of tumor suppressor gene serine-threonine kinase 11 (STK11) in clear cell renal cell carcinoma (ccRCC) has been demonstrated; however, the mechanism of this inactivation remains to be investigated. To investigate whether epigenetic alteration plays a role in the inactivation of STK11 in RCC, the present study aimed to investigate the methylation status of the STK11 promoter and its association with tumor stage and survival in ccRCC patients. Paraffin-embedded specimens were obtained from 42 ccRCC patients. The specimens were analyzed for the methylation status of the STK11 promoter CpG island using methylation-specific polymerase chain reaction. Survival, tumor-node-metastasis (TNM)/American Joint Committee on Cancer (AJCC) stages, and hematological parameters were compared between patients with unmethylated (U), partially methylated (P) and methylated (M) STK11 promoter. Among the 42 patients, there were 12 (28.6%), 18 (42.9%) and 12 (28.6%) patients in the M, P and U groups, respectively. The methylation status of the STK11 promoter was associated with T, N and AJCC stages in RCC. Survival analysis showed that the M group had a significantly shorter survival time compared with the P and U groups. These findings suggested that methylation of the STK11 promoter in RCC is a not rare event, and it may have an important role in the pathogenesis of RCC and be a risk factor for the prognosis of RCC.

The effect of TMEFF2 methylation on the tumor stage and survival outcome of clear cell renal cell carcinoma.

AIM: This study aimed to investigate the methylation status of EGF-like and two follistatin-like domains 2 (TMEFF2) promoter and its correlation with tumor stage and survival outcome in renal cell carcinoma (RCC). MATERIALS AND METHODS: Paraffin-embedded specimens from 42 RCC patients were analyzed for TMEFF2 methylation by methylation-specific polymerase chain reaction. The distribution of TNM/AJCC stages and survival time were compared among patients with unmethylated and methylated TMEFF2. RESULTS: There were 25 (59.5%) and 17 (40.5%) cases with methylated (M group) and unmethylated (M group) TMEFF2, respectively. There were more early-stage cancer patients in U group than in M group. Kaplan-Meier survival analysis showed that U group had a better but not significant survival outcome than M group (P = 0.123). CONCLUSION: These findings showed that TMEFF2 methylation is not rare in RCC, and methylation may play an important role in the tumorigenesis of ccRCC.