trichostatin-a and Cystadenocarcinoma--Serous

Patients suffered from advanced endometrial cancer have poor prognosis. The five-year survival is only 25%. Histone deacetylase inhibitors have shown promise in the treatment for a variety of malignancies. In combination with traditional cytotoxic chemotherapy, histone deacetylase inhibitors can enhance the survival rate of cancer patients. This study was to investigate the effect and mechanism of trichostatin A (TSA), a histone deacetylase inhibitor, combined with paclitaxel (PTX) on the apoptosis of human endometrial carcinoma cell line Ark2.. Ark2 cells were cultured in RPMI-1640 and treated with PTX alone, TSA alone or the two drugs in combination. Cell apoptosis was detected using Annexin V and Hoechst staining; perturbation of mitochondrial membrane potential was detected using MitoTracker red Poly (ADP-ribose) polymerase; caspase-9 degradation products and tubulin acetylation were detected by Western blot.. Results of Annexin V showed that PTX (1.5 nmol/L) plus TSA (25 nmol/L) induced a significantly higher apoptotic rate (45.2%) than PTX alone (14.1%) or TSA alone (11.2%) did in Ark2 cells after drug treatment for three days. The results of Hoechst staining and Annexin V were consistent. A loss of mitochondrial membrane potential could activate the apoptotic cascade. Cleavages of PARP and caspase-9 were significantly apparent in PTX plus TSA group than in PTX group or TSA group (P<0.05). PTX and TSA could induce tubulin acetylation. PTX in combination with TSA increased acetylated tublins and microtubule stability compared with either drug alone. The loss of mitochondrial membrane potential was more dramatic in the drug combination group than the single drug group. The effects of TSA and PTX were synergistic (q=2.54).. TSA and PTX could induce apoptosis of Ark2 cells, which may be through the loss of mitochondrial membrane potential and acetylation of non-histone proteins induced by histone deacetylase inhibitors.

Topics: Acetylation; Antineoplastic Agents, Phytogenic; Apoptosis; Caspase 9; Cell Line, Tumor; Cystadenocarcinoma, Serous; Drug Synergism; Endometrial Neoplasms; Female; Histone Deacetylase Inhibitors; Humans; Hydroxamic Acids; Membrane Potential, Mitochondrial; Microtubules; Paclitaxel; Poly(ADP-ribose) Polymerases; Tubulin

Allelic imbalance on chromosome arm 22q has been detected in 50-70% of ovarian cancers, suggesting the presence of a tumor-suppressor gene on this chromosome arm that is involved in ovarian carcinogenesis. Recently, we isolated a candidate tumor-suppressor gene, MYO18B, at 22q12.1, which is deleted, mutated and hypermethylated in approximately 50% of lung cancers. In our study, we analyzed genetic and epigenetic alterations of the MYO18B gene in ovarian cancers. Missense MYO18B mutations were detected in 1 of 4 (25%) ovarian cancer cell lines and in 1 of 17 (5.9%) primary ovarian cancers. MYO18B expression was reduced in all 4 ovarian cancer cell lines and in 12 of 17 (71%) of primary ovarian cancers. MYO18B expression was restored by treatment with 5-aza-2'-deoxycytidine and/or trichostatin A in 3 of 4 cell lines with reduced MYO18B expression, and hypermethylation of the promoter CpG island for MYO18B was observed in 2 of these 3 cell lines. Its hypermethylation was also observed in 2 of 15 (13%) primary ovarian cancers. Thus, it was indicated that MYO18B expression is reduced in a considerable fraction of ovarian cancers by several mechanisms, including hypermethylation, while the MYO18B gene is mutated in a small subset of ovarian cancers. The present results suggest that MYO18B alterations, including both epigenetic and genetic alterations, play an important role in ovarian carcinogenesis.

Topics: Azacitidine; Carcinoma, Endometrioid; Case-Control Studies; Chromosomes, Human, Pair 22; Cystadenocarcinoma, Mucinous; Cystadenocarcinoma, Serous; Decitabine; DNA Methylation; DNA Mutational Analysis; Female; Genes, Tumor Suppressor; Humans; Hydroxamic Acids; Mutation, Missense; Myosin Heavy Chains; Ovarian Neoplasms; Ovary; Promoter Regions, Genetic; Tumor Cells, Cultured