Prognostic significance of DAPK and RASSF1A promoter hypermethylation in non-small cell lung cancer (NSCLC).

The epigenetic inactivation of tumor suppressor genes may play an important role in the development and progression of many cancer types, including lung cancer. Therefore, we investigated the association between the aberrant promoter methylation of 2 genes: the Death-Associated Protein Kinase (DAPK) and the Ras Association Domain Family 1A (RASSF1A) by using methylation-specific PCR, and the clinicopathological features and prognosis in 70 radically resected non-small cell lung cancers (NSCLCs). Hypermethylation of the DAPK and RASSF1A promoters was found in 24 (34%), and in 18 (26%) tumor DNA samples, respectively. Regarding different clinicopathological features of NSCLCs, the DAPK promoter methylation was more frequently observed in squamous cell carcinoma (46%) than in adenocarcinoma (25%) and large cell carcinoma (22%), but there were no significant statistical differences (p=0.3). On the other hand, a statistically significant trend was observed between the RASSF1A methylation and a histological type of tumor (p=0.06). 45% of adenocarcinoma tumors showed RASSF1A promoter methylation in comparison to 17% of squamous cell carcinomas and 22% of large cell carcinomas. When both markers were analyzed according to the tumor-node-metastasis (TNM) staging system, no statistically significant differences were observed between stage I, II and IIIa, and the DAPK (p=0.2) and RASSF1A methylation (p=0.1). In comparison, when stage I and II were grouped together and considered vs. stage IIIa, a significant association between RASSF1A methylation and the TNM was found (p=0.03). The group of patients with tumors showing DAPK promoter methylation had significantly poorer overall survival rates (p=0.02) than the patients with tumors that did not show DAPK promoter methylation. However, the association between the RASSF1A promoter methylation status and the overall survival rates was not statistically significant (p=0.48). In conclusion, this paper supports the importance of epigenetic gene regulation in lung cancer progression and prognosis

Prognostic significance of DAPK and RASSF1A promoter hypermethylation in non-small cell lung cancer (NSCLC).

The epigenetic inactivation of tumor suppressor genes may play an important role in the development and progression of many cancer types, including lung cancer. Therefore, we investigated the association between the aberrant promoter methylation of 2 genes: the Death-Associated Protein Kinase (DAPK) and the Ras Association Domain Family 1A (RASSF1A) by using methylation-specific PCR, and the clinicopathological features and prognosis in 70 radically resected non-small cell lung cancers (NSCLCs). Hypermethylation of the DAPK and RASSF1A promoters was found in 24 (34%), and in 18 (26%) tumor DNA samples, respectively. Regarding different clinicopathological features of NSCLCs, the DAPK promoter methylation was more frequently observed in squamous cell carcinoma (46%) than in adenocarcinoma (25%) and large cell carcinoma (22%), but there were no significant statistical differences (p=0.3). On the other hand, a statistically significant trend was observed between the RASSF1A methylation and a histological type of tumor (p=0.06). 45% of adenocarcinoma tumors showed RASSF1A promoter methylation in comparison to 17% of squamous cell carcinomas and 22% of large cell carcinomas. When both markers were analyzed according to the tumor-node-metastasis (TNM) staging system, no statistically significant differences were observed between stage I, II and IIIa, and the DAPK (p=0.2) and RASSF1A methylation (p=0.1). In comparison, when stage I and II were grouped together and considered vs. stage IIIa, a significant association between RASSF1A methylation and the TNM was found (p=0.03). The group of patients with tumors showing DAPK promoter methylation had significantly poorer overall survival rates (p=0.02) than the patients with tumors that did not show DAPK promoter methylation. However, the association between the RASSF1A promoter methylation status and the overall survival rates was not statistically significant (p=0.48). In conclusion, this paper supports the importance of epigenetic gene regulation in lung cancer progression and prognosis

GSK-3 inactivation or depletion promotes β-cell replication via downregulation of the CDK inhibitor, p27 (Kip1)

Diabetes (T1DM and T2DM) is characterized by a deficit in β-cell mass. A broader understanding of human β-cell replication mechanism is thus important to increase β-cell proliferation for future therapeutic interventions. Here, we show that p27 (Kip1), a CDK inhibitor, is expressed abundantly in isolated adult human islets and interacts with various positive cell cycle regulatory proteins including D-type cyclins (D1, D2 and D3) and their kinase partners, CDK4 and CDK6. Also, we see interaction of cyclin E and its kinase partner, CDK2, with p27 suggesting a critical role of p27 as a negative cell cycle regulator in human islets. Our data demonstrate interaction of p27 with GSK-3 in β-cells and show, employing rodent β-cells (INS-1), isolated human islets and purified β-cells derived from human islets, that siRNA-mediated depletion of GSK-3 or p27 or 1-AKP/BIO-mediated GSK-3 inhibition results in increased β-cell proliferation. We also see reduction of p27 levels following GSK-3 inactivation or depletion. Our data show that serum induction of quiescent INS-1 cells leads to sequential phosphorylation of p27 on its S10 and T187 residues with faster kinetics for S10 corresponding with the decreased levels of p27. Altogether our findings indicate that p27 levels in β-cells are stabilized by GSK-3 and thus p27 downregulation following GSK-3 depletion/inactivation plays a critical role in promoting β-cell replication