Aberrant promoter methylation and silencing of RASSF2A gene in cervical cancer

Decreased expression of RASSF10 correlates with poor prognosis in patients with colorectal cancer

Ras association domain protein 10 (RASSF10) was reported to act as a prognostic indicator in various types of cancer and it was proved to be tumor suppressor gene in colorectal cancer (CRC). The purpose of this study was to evaluate the prognostic significance of RASSF10 in CRC.Quantitative real-time polymerase chain reaction was used to detect the messenger RNA (mRNA) expression while enzyme-linked immunosorbent assay was taken to measure the protein expression of RASSF10 in tumor tissues and adjacent normal tissues from 102 patients with CRC. The relationship between RASSF10 expression level and clinical characteristics of CRC patients was analyzed by chi-squared test. In addition, the association between overall survival of CRC patients and RASSF10 expression was estimated by Kaplan-Meier analysis. Cox regression analysis was used to evaluate the prognostic value of RASSF10.The expression level of RASSF10 in tumor tissues was significantly lower than that in the normal tissues both at mRNA and protein levels. Moreover, the expression level was correlated with lymph-node-metastasis and tumor-node-metastasis stage. Kaplan-Meier analysis suggested that patients with high expression level of RASSF10 had a longer overall survival than those with low level (log-rank test, P < .001). Besides, RASSF10 might be a potential biomarker in the prognosis of CRC according to cox regression analysis.The down regulated of RASSF10 is found in CRC and it may be an ideal prognostic marker.

Prognostic importance of RASSF2 expression in patients with gastric cancer who had undergone radical gastrectomy

BACKGROUND

Although Ras-association domain family of gene 2 (RASSF2) has been shown to undergo promoter methylation at high frequency in some cancer types and in brain metastases, its clinical utility as a useful prognostic molecular marker remains unclear in gastric cancer.

METHODS

Prognostic significance of RASSF2 expression was retrospectively analysed by immunohistochemically in 105 patients with gastric cancer who underwent curative gastrectomy.

RESULTS

Low RASSF2 expression was detected in 58 (55 %) patients, whereas 47 patients (45 %) had high RASSF2 expression. Lymph node involvement, pT stage, TNM stage, vascular invasion, perineural invasion and the presence of recurrence were found to be significantly related to RASSF2 expression levels. Low PRL-3 expression was closely correlated with lymph node metastasis (p = 0.001), advanced pT stage (p = 0.021), advanced TNM stage (p < 0.001), the presence of vascular invasion (p < 0.001), perineural invasion (p = 0.018) and high prevalence of recurrence (p = 0.003) compared with high RASSF2 expression. The median disease-free survival (DFS) time for patients with low RASSF2 expression was significantly worse than that of patients with high RASSF2 expression (10.2 vs. 50.6 months, p < 0.001). In addition, patients with high RASSF2 expression had the higher overall survival (OS) interval compared to patients with low RASSF2 expression (NR vs. 14.9 months, p < 0.001). In the multivariate analysis, the rate of RASSF2 expression levels was an independent prognostic factor, for DFS [p < 0.001, HR 0.12 (0.10-0.88)] and OS [p < 0.001, HR 0.10 (0.04-0.46)], as were pT stage and TNM stage, respectively.

CONCLUSIONS

RASSF2 may be an important molecular marker for carcinogenesis, prognosis and progression in gastric cancer, but the potential value of RASSF2 expression as a useful molecular marker in gastric cancer progression should be evaluated, comprehensively. It would be possible to develop treatments targeting RASSF2 and advance new treatment strategies for gastric cancer.

Differential involvement of RASSF2 hypermethylation in breast cancer subtypes and their prognosis

Breast cancer is a heterogeneous disease that can be subdivided into clinical, histopathological and molecular subtypes (luminal A-like, luminal B-like/HER2-negative, luminal B-like/HER2-positive, HER2-positive, and triple-negative). The study of new molecular factors is essential to obtain further insights into the mechanisms involved in the tumorigenesis of each tumor subtype. RASSF2 is a gene that is hypermethylated in breast cancer and whose clinical value has not been previously studied. The hypermethylation of RASSF1 and RASSF2 genes was analyzed in 198 breast tumors of different subtypes. The effect of the demethylating agent 5-aza-2'-deoxycytidine in the re-expression of these genes was examined in triple-negative (BT-549), HER2 (SK-BR-3), and luminal cells (T-47D). Different patterns of RASSF2 expression for distinct tumor subtypes were detected by immunohistochemistry. RASSF2 hypermethylation was much more frequent in luminal subtypes than in non-luminal tumors (p = 0.001). The re-expression of this gene by lentiviral transduction contributed to the differential cell proliferation and response to antineoplastic drugs observed in luminal compared with triple-negative cell lines. RASSF2 hypermethylation is associated with better prognosis in multivariate statistical analysis (P = 0.039). In conclusion, RASSF2 gene is differently methylated in luminal and non-luminal tumors and is a promising suppressor gene with clinical involvement in breast cancer.