RASSF1A Suppresses Cell Migration through Inactivation of HDAC6 and Increase of Acetylated alpha-Tubulin / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The RAS association domain family protein 1 (RASSF1) has been implicated in a tumor-suppressive function through the induction of acetylated alpha-tubulin and modulation of cell migration. However, the mechanisms of how RASSF1A is associated with acetylation of alpha-tubulin for controlling cell migration have not yet been elucidated. In this study, we found that RASSF1A regulated cell migration through the regulation of histon deacetylase 6 (HDAC6), which functions as a tubulin deacetylase. MATERIALS AND METHODS: The cell migration was assessed using wound-healing and transwell assays. The role of RASSF1A on cell migration was examined by immunofluorescence staining, HDAC activity assay and western blot analysis. RESULTS: Cell migration was inhibited and cell morphology was changed in RASSF1A-transfected H1299 cells, compared with controls, whereas HDAC6 protein expression was not changed by RASSF1A transfection in these cells. However, RASSF1A inhibited deacetylating activity of HDAC6 protein and induced acetylated alpha-tubulin expression. Furthermore, acetylated alpha-tubulin and HDAC6 protein were co-localized in the cytoplasm in RASSF1A-transfected H1299 cells. Conversely, when the endogenous RASSF1A expression in HeLa cells was blocked with RASSF1A siRNA treatment, acetylated alpha-tubulin was co-localized with HDAC6 protein throughout the whole cells, including the nucleus, compared with scramble siRNA-treated HeLa cells. The restoration of RASSF1A by 5-Aza-dC treatment also induced acetylated alpha-tubulin through inhibition of HDAC6 activity that finally resulted in suppressing cell migration in H1299 cells. To further confirm the role of HDAC6 in RASSF1A-mediated cell migration, the HDAC6 expression in H1299 cells was suppressed by using HDAC6 siRNA, and cell motility was found to be decreased through enhanced acetylated alpha-tubulin. CONCLUSION: The results of this study suggest that the inactivation of HDAC6 by RASSF1A regulates cell migration through increased acetylated alpha-tubulin protein.

The Blocking of c-Met Signaling Induces Apoptosis through the Increase of p53 Protein in Lung Cancer / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: c-Met is an attractive potential target for novel therapeutic inhibition of human cancer, and c-Met tyrosine kinase inhibitors (TKIs) are effective growth inhibitors of various malignancies. However, their mechanisms in anticancer effects are not clear. In the present study, we investigated the possibility that blocking c-Met signaling induces p53-mediated growth inhibition in lung cancer. MATERIALS AND METHODS: The growth inhibitory effects of c-Met TKI (SU11274) on lung cancer cells and a xenograft model were assessed using the MTT assay, flow cytometry, and terminal deoxyribonucleotide transferase-mediated nick-end labeling staining. The role of p53 protein in the sensitivity of c-Met TKI (SU11274) was examined by Western blot analysis and immunohistochemistry. RESULTS: SU11274 significantly induced apoptosis in A549 cells with wild-type p53, compared with that in Calu-1 cells with null-type p53. SU11274 increased p53 protein by enhancing the stability of p53 protein. Increased p53 protein by SU11274 induced up-regulation of Bax and PUMA expression and down-regulation of Bcl-2 expression, subsequently activating caspase 3. In p53 knock-out and knock-in systems, we confirmed that SU11274 caused apoptosis through the p53-mediated apoptotic pathway. Likewise, in the A549 xenograft model, SU11274 effectively shrank tumor volume and induced apoptosis via increased p53 protein expression. Blocking c-Met signaling increased the level of p53 protein. CONCLUSION: Our finding suggested that p53 plays an important role in SU11274-induced apoptosis, and p53 status seems to be related to the sensitivity to SU11274 in lung cancer.

An Association Study of Polymorphisms in JAK3 Gene with Lung Cancer in the Korean Population / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: The genetic alteration of the janus kinases (JAKs), non-receptor tyrosine kinase, is related to the development of human cancers. However, little is known about how the sequence variation of JAK3 contributes to the development of lung cancer. This study investigated whether polymorphisms at the promoter region of the JAK3 gene are associated with the risk of lung cancer in the Korean population. MATERIALS AND METHODS: A total of 819 subjects, including 409 lung cancer patients and 410 healthy controls were recruited. The SNaPshot assay and polymerase chain reaction-restriction fragment length polymorphism analysis were used, and logistic regression analyses were performed to characterize the association between polymorphisms of JAK3 and lung cancer risk. RESULTS: Three polymorphisms (-672 G>A, +64 A>G and +227 G>A) of JAK3 were analyzed for large-scale genotyping (n=819). Statistical analyses revealed that polymorphisms and haplotypes in the JAK3 gene were not significantly associated with lung cancer. CONCLUSION: JAK3 gene was not significantly associated with the risk of lung cancer in the Korean population.

Correlation between Retinoic Acid Sensitivity and IGFBP-3, AFP Protein Expression in Hepatoma Cell Lines / Journal of the Korean Cancer Association, 대한암학회지

PURPOSE: Retinoic acid (RA) has been known to inhibit the proliferation, and to induce apoptosis, of various cancer cell lines. We investigated the correlation between the protein levels of the RAR and RXR receptor families, IGFBP-3 and AFP, and the RA sensitivity in hepatoma cell lines. MATERIALS AND METHODS: The cell growth inhibition was examined by assaying various 1 to 10muM RA treated hepatoma cell lines. Western blot analysis for the RAR and RXR families, AFP and IGFBP-3 were performed after treatment with 10muM RA. RESULTS: The 1 to 10muM RA treatment induced growth inhibition in the SNU368, SNU354, SNU398 and HepG2 cells. The cell growth of SNU449 and Hep3B were not suppressed by 1muM, but were slightly suppressed by 10muM RA. An increased expression of IGFBP-3 in HepG2, SNU354, SNU398 and SNU368 cells, and a decreased expression of alpha-fetoprotein (AFP), was observed from the western blot analysis in all hepatoma cells tested, whereas no confirmed tendency of RAR expressions was seen. CONCLUSION: Our result showed that the growth inhibition of RA differed according to the sensitivity of the type of cells to RA. We supposed that RA-induced cell growth inhibition may be related to the expressions of IGFBP-3 and AFP, but no exact correlation exists between the growth inhibition and receptor expression status in hepatoma cell lines.