No abstract

Histone deacetylase (HDAC) inhibitors represent a promising group of anticancer agents. This paper shows that the HDAC inhibitor suberoylanilide hydroxamic acid (SAHA) stimulated at 5-10 microM apoptosis in human hepatoma HepG2 and Huh6 cells, but was ineffective in primary human hepatocytes (PHH). In HepG2 cells SAHA induced the extrinsic apoptotic pathway, increasing the expression of both FasL and FasL receptor and causing the activation of caspase-8. Moreover, SAHA enhanced the level of Bim proteins, stimulated alternative splicing of the Bcl-X transcript with the expression of the proapoptotic Bcl-Xs isoform, induced degradation of Bid into the apoptotic factor t-Bid and dephosphorylation and inactivation of the anti-apoptotic factor Akt. Consequently, SAHA caused loss of mitochondrial transmembrane potential, release of cytochrome c from mitochondria, activation of caspase-3 and degradation of PARP. Interestingly, a combination of suboptimal doses of SAHA (1 microM) and bortezomib (5-10 nM), a potent inhibitor of 26S proteasome, synergistically induced apoptosis in both HepG2 and Huh6 cells, but was ineffective in PHH. Combined treatment increased with synergistic effects the expression levels of c-Jun, phospho-c-Jun and FasL and the production of Bcl-Xs. These effects were accompanied by activation of Bid, caspase-8 and 3. In conclusion, SAHA stimulated apoptosis in hepatoma cells and exerted a synergistic apoptotic effect when combined with bortezomib. In contrast, these treatments were quite ineffective in inducing apoptosis in PHH. Thus, our results suggest the potential application of the SAHA/bortezomib combination in clinical trials for liver cancer.

Objective response rates to standard chemotherapeutic regimens remain low in pancreatic cancer. Subpopulations of cells have been identified in various solid tumors which express stem cell-associated markers and are associated with increased resistance against radiochemotherapy. We investigated the expression of stem cell genes and markers of epithelial-mesenchymal transition in pancreatic cancer cells that survived high concentrations of gemcitabine treatment. Capan-1 and Panc-1 cells were continuously incubated with 1 and 10 µM gemcitabine. Surviving cells were collected after 1, 3 and 6 days. Expression of PDX-1, SHH, CD24, CD44, CD133, EpCAM, CBX7, OCT4, SNAIL, SLUG, TWIST, Ki-67, E-cadherin, β-catenin and vimentin were quantified by qPCR or immunocytochemistry. Migration was assessed by wound‑healing assay. SHH was knocked down using RNA interference. Five primary pancreatic cancer cell lines were used to validate the qPCR results. All investigated genes were upregulated after 6 days of gemcitabine incubation. Highest relative expression levels were observed for OCT4 (13.4-fold), CD24 (47.3-fold) and EpCAM (15.9-fold) in Capan-1 and PDX-1 (13.3‑fold), SHH (24.1-fold), CD44 (17.4-fold), CD133 (20.2-fold) and SLUG (15.2-fold) in Panc-1 cells. Distinct upregulation patterns were observed in the primary cells. Migration was increased in Panc-1 cells and changes in the expression of E-cadherin and β-catenin were typical of epithelial-mesenchymal transition in both cell lines. SHH knockdown reduced IC(50) from 30.1 to 27.6 nM in Capan-1 while it strongly inhibited proli-feration in Panc-1 cells. Cells surviving high-dose gemcitabine treatment express increased levels of stem cell genes, show characteristics associated with epithelial-mesenchymal transition and retain their proliferative capacity.

Histone deacetylases (HDAC) are responsible for the transcriptional control of genes through chromatin remodeling and control tumor suppressor genes. In several tumors, their expression has been linked to clinicopathological factors and patient survival. This study investigates HDACs 1, 2, 3, and 7 expressions in hepatocellular carcinoma (HCC) and their correlation with clinical data and patient survival. Tissue microarrays of 170 surgically resected primary HCCs and adjacent uninvolved tissue were evaluated immunohistochemically for the expression of HDACs 1, 2, 3, 7, and Ki-67 and were analyzed with respect to clinicopathological data and patient survival. HDACs 1, 2, 3, and Ki-67 were expressed significantly higher in cancer cells compared to normal tissue (HDAC1: p = 0.034, HDACs 2 and 3 and Ki-67: p < 0.001), while HDAC7 expression did not differ between HCC and non-cancerous liver tissue. In tumor tissue HDACs 1-3 expression levels showed high concordance with each other, Ki-67 and tumor grade (p < 0.001). High HDAC2 expression was associated with poor survival in low-grade and early-stage tumors (p < 0.05). The expression of the HDACs 1, 2, and 3 (but not HDAC7) isoenzymes correlates with clinicopathological factors, and HDAC2 expression has an impact on patient survival.

A metal complex is identified in which the metal fulfills two independent functions: as a structural scaffold for the specific molecular recognition of protein kinases resulting in antiangiogenic properties, together with a visible-light-induced photoreactivity triggering apopotosis in cancer cells.