Inflammatory bowel disease (IBD) is an inflammatory disorder of the gastrointestinal tract that is caused by multiple factors, including dysfunction of the immune system and genetic and epigenetic alterations. Aberrant epigenetic regulation, especially histone acetylation, was found in biopsies from IBD patients and mouse models of colitis, suggesting that an epigenetic treatment approach may be useful for IBD therapy. Therefore, we investigated the effects of the histone deacetylase (HDAC) inhibitor, suberoylanilide hydroxamic acid (SAHA), in a mouse model of dextran sulfate sodium (DSS)-induced colitis. C57BL/6 mice were treated with 1.5% DSS for 5 days and/or SAHA (25 mg/kg BW/day) for 26 days. Levels of mRNA for the pro-inflammatory cytokines, interleukin (IL)-6 and tumor necrosis factor (TNF)-α, and the chemokines, Ccl2, were examined by qRT-PCR. CD11b, a marker of dendritic cells, macrophages, and monocytes, as well as Ccl2 expression, were examined by immunohistochemistry. IL-6, TNF-α, and Ccl2 gene expression peaked on day 5 in DSS-treated mouse colon, whereas SAHA treatment significantly decreased pro-inflammatory gene expression. Ccl2 protein expression resembled Ccl2 gene expression results. Moreover, localization of CD11b showed that migratory inflammatory cells were dramatically decreased by SAHA treatment compared to DSS-treated mouse colon. Thus, we conclude that the HDAC inhibitor, SAHA, attenuates inflammatory changes in DSS-induced colitis by suppressing local secretion of pro-inflammatory cytokines and chemokines and also by suppressing mobilization and accumulation of inflammatory cells.

Hepatoid adenocarcinoma (HAC) is a rare and aggressive gastrointestinal tract cancer that is characterized by hepatic differentiation and production of alpha-fetoprotein (AFP). Cisplatin is mainly used to treat HAC, but the efficacy is poor. Recently, the histone deacetylase inhibitor, suberoylanilide hydroxamic acid (SAHA), was approved as an anticancer agent. In this study, we investigated the anticancer effect of SAHA in combination with cisplatin in VAT-39 cells, a newly established HAC cell line. Cell viability and apoptosis were examined by MTT assay, flow cytometry and TUNEL assay. Expression of H3S10, cleaved caspase-3, Bax, and Bcl-2 were evaluated by immunohistochemistry and western blotting. AFP levels were examined in VAT-39 cells and culture medium. Combined treatment with cisplatin and SAHA efficiently inhibited cell proliferation and decreased cell viability. Apoptotic cells, but not necrotic cells, were significantly increased following the combined treatment, and an increase in the Bax/Bcl-2 ratio indicated that the combination of cisplatin and SAHA induced apoptosis through the mitochondrial pathway. VAT-39 cells treated with cisplatin and SAHA also partially lost their main characteristic of AFP production. We conclude that cisplatin and SAHA have a synergistic anticancer effect of inducing apoptosis, and that this combination treatment may be effective for HAC.

Estrogen affects mitochondrial function in various tissues, but the precise mechanism remains unclear. We, therefore investigated the effect on estrogen-regulated mitochondrial morphology by dynamin-related protein 1 (Drp1) and its Ser616-phosphorylated derivative (pDrp1Ser616) are involved in mitochondrial fission. MCF7 human breast cancer cells were treated with 17β-estradiol (E2), an estrogen receptor (ER) α and β antagonist (ICI 182, 780), an ERα antagonist (MPP), and an ERβ antagonist (PHTPP) for 24 hr. The expression of Drp1 and pDrp1Ser616 was analyzed by western blotting and immunohistochemistry. Mitochondrial morphology was analyzed by transmission electron microscopy (TEM). In control cells, Drp1 was detected in the cytoplasm of all cells while pDrp1 was observed in the cytoplasm of 3.4 ± 1.0% of the total population. After E2 treatment, pDrp1Ser616-positive cells comprised 30.6 ± 5.6% of the total population, 10.5 ± 1.7% after E2 + ICI treatment, 12.4 ± 4.2% after E2 + MPP treatment, and 24.0 ± 2.2% after E2 + PHTPP treatment. In ERα knockdown MCF7 cells, pDrp1 expression was decreased after E2 treatment compared to E2-treated wild type cells. Tubular pattern mitochondria were found in the control cells but the number of short and small pattern mitochondria (< 0.5 μm2) was significantly increased after E2 treatment (as observed by TEM). We, therefore concluded that the phosphorylation of Drp1 is important for E2-dependent mitochondrial morphological changes through ERα.

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