apicidin and Carcinoma--Hepatocellular

Topics: Calcium-Calmodulin-Dependent Protein Kinase Type 2; Calmodulin; Carcinoma, Hepatocellular; Cell Line, Tumor; Humans; Liver Neoplasms; MAP Kinase Signaling System; Mitogen-Activated Protein Kinase 1; Mitogen-Activated Protein Kinase 3; Mitogen-Activated Protein Kinases; Peptides, Cyclic; Signal Transduction

Despite rapid advances in the diagnostic and surgical procedures, hepatocellular carcinoma (HCC) remains one of the most difficult human malignancies to treat. This may be due to the chemoresistant behaviors of HCC. It is believed that acquired resistance could be overcome and improve the overall survival of HCC patients by understanding the mechanisms of chemoresistance in HCC. A stable HA22T cancer line, which is chronically resistant to a histone deacetylase inhibitor, was established. After comparing the molecular mechanism of apicidin-R HA22T cells to parental ones by Western blotting, cell cycle-regulated proteins did not change in apicidin-R cells, but apicidin-R cells were more proliferative and had higher tumor growth (wound-healing assay and nude mice xenograft model). Moreover, apicidin-R cells displayed increased levels of p-IGF-IR, p-PI3K, p-Akt, Bcl-xL, and Bcl-2 but also significantly inhibited the tumor suppressor PTEN protein and apoptotic pathways when compared to the parental strain. Therefore, the highly proliferative effect of apicidin-R HA22T cells was blocked by Akt knockdown. For all these findings, we believe that novel strategies to attenuate IGF-IR/PI3K/Akt signaling could overcome chemoresistance toward the improvement of overall survival of HCC patients.

Topics: Animals; Antineoplastic Agents; Apoptosis; Carcinoma, Hepatocellular; Cell Cycle Proteins; Cell Line, Tumor; Cell Proliferation; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Gene Knockdown Techniques; Histone Deacetylase Inhibitors; Humans; Inhibitory Concentration 50; Liver Neoplasms; Mice; Peptides, Cyclic; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Receptor, IGF Type 1; RNA Interference; Signal Transduction

The IGF-IR/PI3K/Akt signaling pathway inhibited GSK3-β activity by phosphorylation and this promoted β-catenin nuclear localization. Our previous study indicated that β-catenin mRNA level was significantly higher in tumor areas than in non-tumor ones, especially in late pathologic stage tumors. However, β-catenin inhibition resulted in significantly suppressed migration and invasion ability of HA22T cells. Thus, Wnt/β-catenin pathway over-activation might be involved in metastatic enhancement of apicidin-resistant HA22T cell metastasis. Apicidin-resistant (AR) HA22T cells showed higher β-catenin nuclear accumulation and significantly decreased GSK-3-β protein level, in relation to parental cells. Results also indicated that AR cells increased abundantly in Tbx3, a downstream target of Wnt/β-catenin that it is implicated in liver cancer. AR cells also inhibited the MEK/ERK/PEA3 pathway which promoted MMP-2 activation. But, apicidin-resistant effect was totally reversed by LY294002 and AG1024. In conclusion, Apicidin-R HA22T cells activated the Wnt/β-catenin pathway and induced, MMP-2 expression via IGF-IR/PI3K/Akt signaling further enhancing cell the metastatic effects.

Topics: beta Catenin; Carcinoma, Hepatocellular; Cell Line, Tumor; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; Humans; Liver Neoplasms; Matrix Metalloproteinase 2; Neoplasm Invasiveness; Neoplasm Metastasis; Peptides, Cyclic; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Receptor, IGF Type 1; Signal Transduction; Up-Regulation; Wnt Proteins

The molecular and phenotypic associations between chemo- or radio-resistance and the acquisition of epithelial-mesenchymal transition (EMT)-like phenotype are tightly related in cancer cells. Wnt/β- catenin and NF-κB signaling pathways play crucial roles in EMT induction. Apicidin-resistant (Apicidin- R) HA22T cells are known to activate the Wnt/β-catenin signaling pathway and MMP-2 expression via the IGF-IR/PI3K/Akt signaling pathway to enhance metastatic effects of cancer cells. In this study, we further investigated if Apicidin-R HA22T cells actually underwent EMT. In Apicidin-R HA22T cells, E-cadherin protein level was reduced but Vimentin, Snail and Twist were significantly activated. Activation of p-IKKαβ and p-IκBα was also observed in Apicidin-R HA22T cells. Apicidin-R HA22T cells displayed even higher NF-κB nuclear accumulation. Snail was enhanced but GSK3-β was reduced. However, unphosphorylated GSK3-β protein level was totally reversed when the Snail-specific siRNA was applied in a knockdown experiment. Taken together, Apicidin-R HA22T cells could potentiate aggressive metastasis behavior due to up-regulation of Snail expression and promoted EMT effects via the IKKαβ/NF-κB pathway. In addition, Snail might decrease the GSK3-β level resulting in extraordinarily activation of Wnt/β-catenin signaling pathway.

Topics: Carcinoma, Hepatocellular; Cell Line, Tumor; Drug Resistance, Neoplasm; Epithelial-Mesenchymal Transition; Glycogen Synthase Kinase 3; Glycogen Synthase Kinase 3 beta; Histone Deacetylase Inhibitors; Humans; I-kappa B Kinase; Liver Neoplasms; NF-kappa B; Peptides, Cyclic; Signal Transduction; Snail Family Transcription Factors; Transcription Factors