Do iron chelators increase the antiproliferative effect of trichostatin A through a glucose-regulated protein 78 mediated mechanism?

Histone deacetylase (HDAC) inhibitors, such as trichostatin A (TSA), and iron chelators, including deferoxamine (DFO) and phenanthroline (PHEN), appear to have anticancer effects. We hypothesized that the HDAC inhibitors and iron chelators would be synergistic with their effect on breast cancer cell line MCF7, because the HDAC inhibitors increase glucose-regulated protein 78 (Grp78) and the iron chelators reduce its expression. Although the administration of TSA alone resulted in a dose-related decrease in the cell index, it did not have an antiproliferative effect except the 62.5 and 500 nM of TSA. However, all doses of TSA produced a cytotoxic effect from the initial hours when combined with 150 µM of DFO and 25 µM of PHEN. DFO and PHEN downregulated Grp78, Grp94, and MRP1 expressions and upregulated CHOP and HO-1 expressions. TSA upregulated all the genes in various rates when used alone but resulted in decreased expression levels when combined with DFO and PHEN. Increased HDAC-1 levels in the Grp78 promoter region indicated that DFO and PHEN either promoted binding of HDAC-1 to this region or inhibited its detachment. We determined that the reduction of increased Grp78, Grp94, HO-1, and MRP1 expressions, which appears to inhibit the chemotherapeutic effect of TSA, through the combination with DFO or PHEN will contribute to the anticancer effect.

Effect of creatine and pioglitazone on Hk-2 cell line cisplatin nephrotoxicity.

Cisplatin is a chemotherapeutic agent, which is used in the treatment of various solid organ cancers, and its main dose limiting side effect of cisplatin is nephrotoxicity. The aim of this study is to investigate the role of pioglitazone and creatine on cisplatin nephrotoxicity in vitro. Real-time cell analyzer system (RTCA) was used for real-time and time-dependent analysis of the cellular response of HK-2 cells following incubation with cisplatin and combination with creatine or pioglitazone hydrochloride. First, half-maximal inhibitory concentrations (IC50) of cisplatin, creatine and pioglitazone were calculated by RTCA system. Afterwards creatine and pioglitazone was administered with serial dilutions under RTCA system. IC50 dose for cisplatin was 7.69 M × 10(-5) at 24th hour and 3.93 M × 10(-6) at 48th hour. IC50 dose for pioglitazone was 1.61 M × 10(-3) at 24th hour and 2.85 M × 10(-4) at 48th hour. Although cells were treated the dose of 40,225 mM creatine, IC50 dose could not been reached. Neither pioglitazone nor creatine had additional protective effect in any dose. Consequently, beneficial effect of creatine and pioglitazone on cisplatin-induced cell death could not be found. Further studies and clinical trials are needed to evaluate the effect of different doses of these drugs in cisplatin-induced nephrotoxicity.

Effect of dexamethasone on unfolded protein response genes (MTJ1, Grp78, Grp94, CHOP, HMOX-1) in HEp2 cell line.

The endoplasmic reticulum (ER) is related to the various signal routes that are activated in unfolded protein response (UPR). The Grp78, Grp94, CHOP, MTJ1 and HMOX1 genes expressions demonstrate UPR activity. In this study, we investigated the UPR gene expressions in larynx epidermoid carcinoma (HEp2) to which dexamethasone (dex) was applied. HEp2 cells were administered for 48 h with different combinations using 0.1 microM and 1 microM dex, 1 mM phenyl butyric acid (PBA) and 100 ng/ml lipopolysaccharide (LPS). The Grp78, Grp94, CHOP, MTJ1 and HMOX1 genes expression was determined using quantitative RT-PCR. The Grp78, MTJ1 and HMOX1 gene expression increased with the administration of 1 microM dex. CHOP expression, on the other hand, decreased with 0.1 microM dex. When dex was combined with LPS, nearly all gene expressions decreased. The increase in Grp78, Grp94, HMOX1 and MTJ1 gene expression was greater in groups in which dex was administered in combination with PBA than in groups in which dex was administered alone. Dex in low dose (0.1 microM) caused a decrease in CHOP expression in HEp2 cells and an increase in Grp78 expression, in particular. The changes in UPR genes expressions may lead to the extended survival of the cells.

The effect of ouabain on mitochondrial DNA damage in HepG2 cell lines.

Our purpose in this study is to analyze mitochondrial DNA (mtDNA) lesion frequencies and mtDNA(4977) deletion in HepG2 cells to examine the effects of ouabain on mtDNA. HepG2 cells were treated with 0.75, 7.5, 75, and 750 nM of ouabain for 24 h in the presence and absence of 10 mM 2-deoxyglucose (2-DG). The frequency of mtDNA(4977) deletions and mitochondrial lesions were determined by real-time polymerase chain reaction. A ≥ 1.2-fold change or greater was considered significant. Ouabain doses of 750, 75, and 7.5 nM alone increased the frequency of mtDNA(4977) deletions 1.39, 1.92, and 1.44 times, respectively. The 750 and 75 nM ouabain doses combined with 2-DG increased the mtDNA(4977) deletion frequency 4.94 and 1.57 times, respectively. The 750 and 75 nM ouabain doses alone increased the mtDNA lesion frequency 2.5 and 1.5 times, respectively. The 750 nM ouabain dose combined with 2-DG increased the mtDNA lesion frequency 2.28 times. The 7.5 nM ouabain dose alone and combined with 2-DG decreased the mtDNA lesion frequency 0.67 and 0.45 times, respectively. Ouabain alone and when combined with 2-DG increases mtDNA lesion and mtDNA(4977) deletion frequencies. This supports the thesis that ouabain creates oxidative stress and induces DNA damage and apoptosis.

The anticancer effects of desferrioxamine on human breast adenocarcinoma and hepatocellular carcinoma cells.

N-myc downstream-regulated gene 1 (NDRG1) is defined as metastasis suppressor and can be downregulated in many types of cancers, and reported to be an indication of tumor progression in hepatocellular carcinomas. Several in-vivo and in-vitro studies have demonstrated that iron chelators such as Desferrioxamine (DFO) and 1-10 Phenanthroline (PHEN) are effective antitumor agents. It is suggested that these chelators deliver their antitumor activity by acting on the NDRG1 gene expression. It remains unclear why NDRG1 gene expression affects the tumors differently, or becomes affected differently. We consider that this different effect might be caused by variants. Based on this information, we developed specific primers and probes for NDRG1 mRNA variants using bioinformatics analysis, and investigated how DFO and PHEN affected the dynamics of NDRG1 variant on the cell lines of Human Breast Adenocarcinoma (MCF-7) and Hepatocellular Carcinoma (HepG2) that demonstrate opposite action for the relationship NDRG1-metastasis. We administrated various doses of DFO and PHEN into the cells to monitor cell vitality and proliferation with Real time Cell Analyzer. We analyzed the gene expression levels of study groups with Quantitative RT-PCR as well as relative gene expression. Variants of NDRG1 mRNA were transcriptionally regulated after HepG2 and MCF-7 cells were treated by iron chelators, resulting in domination of NDRG1 mRNA Variant 1 (V1) in the HepG2 calls and domination of NDRG1 mRNA Variant 2 (V2) in the MCF-7 cells. Anti-proliferative and cytotoxic effects were observed in the MCF-7 cells whereas an increased proliferation was present in the HepG2 cells.

Ouabain targets the unfolded protein response for selective killing of HepG2 cells during glucose deprivation.

Ouabain is a cardiotonic steroid and specific inhibitor of the Na(+)/K(+)-ATPase. The relationship between ouabain treatment and the unfolded protein response (UPR) in cells is not precisely understood. Therefore, we studied the possible effects of ouabain on proliferation, apoptosis, and the UPR. HepG2 cells were cultured overnight and then treated with various concentrations of ouabain (0.75 to 750 nM) in the absence or presence of 10 mM 2-deoxyglucose (2-DG) for 48 hours. We also used real-time polymerase chain reaction to obtain quantitative measurements of expression levels of Grp78, Grp94, CHOP, MTJ-1, HKII, MDR-1, MRP-1, HO-1, and Par-4. Cell number, viability, and proliferation of HepG2 cells were monitored with a real-time cell analyzer system (xCELLigence). We show that ouabain modulates the UPR transcription program and induces cell death in glucose-deprived tumor cells. Ouabain at all concentrations showed no cytotoxicity whereas all concentrations were very effective under 2-DG stress conditions. Our findings show that disruption of the UPR during glucose deprivation could be an attractive approach for selective cancer cell killing and could provide a chemical basis for developing UPR-targeting drugs against solid tumors. Ouabain use as an adjunct to conventional cancer therapy also warrants vigorous investigation.