Necrotic pathway in human osteosarcoma Saos-2 cell death induced by chloroacetaldehyde

An in vitro cytotoxicity of glufosfamide in HepG2 cells relative to its nonconjugated counterpart

BACKGROUND

Glufosfamide (β-D-glucosylisophosphoramide mustard, GLU) is an alkylating cytotoxic agent in which ifosforamide mustard (IPM) is glycosidically linked to the β-D-glucose molecule. GLU exerted its cytotoxic effect as a targeted chemotherapy. Although, its cytotoxic efficacy in a number of cell lines, there were no experimental or clinical data available on the oncolytic effect of oxazaphosphorine drugs in hepatocellular carcinoma. Therefore, the main objective of the current study is to assess the cytotoxic potential of GLU for the first time in the hepatocellular carcinoma HepG2 cell line model.

METHODS

Cytotoxicity was assayed by the MTT method, and half-maximal inhibitory concentration (IC₅₀) was calculated. Flow cytometric analysis of apoptosis frequencies was measured by using Annexin V/PI double stain, an immunocytochemical assay of caspase-9, visualization of caspase-3, and Bcl2 gene expression were undertaken as apoptotic markers. Mitochondrial membrane potential was measured using the potentiometric dye; JC-1, as a clue for early apoptosis as well as ATP production, was measured by the luciferase-chemiluminescence assay.

RESULTS

Glufosfamide induced cytotoxicity in HepG2 cells in a concentration- and time-dependent manner. The IC₅₀ values for glufosfamide were significantly lower compared to ifosfamide. The frequency of apoptosis was much higher for glufosfamide than that of ifosfamide. The contents of caspase-9 and caspase-3 were elevated following exposure to GLU more than IFO. The anti-apoptotic Bcl2 gene expression, the mitochondrial membrane potential, and the cellular ATP levels were significantly decreased than in case of ifosfamide.

CONCLUSIONS

The current study reported for the first time cytotoxicity activity of glufosfamide in HepG2 cells in vitro. The obtained results confirmed the higher oncolytic activity of glufosfamide than its aglycone ifosfamide. The generated data warrants further elucidations by in vivo study.

Loss of Mitochondrial DNA by Gemcitabine Triggers Mitophagy and Cell Death

Gemcitabine (2,2-difluorodeoxycytidine nucleic acid), an anticancer drug exhibiting a potent ability to kill cancer cells, is a frontline chemotherapy drug. Although some chemotherapeutic medicines are known to induce nuclear DNA damage, no investigation into mitochondrial DNA (mtDNA) damage currently exists. When we treated insulinoma pancreatic β-cells (line INS-1) with high mitochondrial activity with gemcitabine for 24 h, the mtDNA contents were decreased. Gemcitabine induced a decrease in the number of mitochondria and the average potential of mitochondrial membrane in the cell but increased the superoxide anion radical levels. We observed that treatment with gemcitabine to induce cell death accompanied by autophagy-related protein markers, Atg5 and Atg7; these were significantly prevented by the autophagy inhibitors. The localization of Atg5 co-occurred with the location of mitochondria with membranes having high potential and mitophagy in cells treated with gemcitabine. The occurrence of mitophagy was inhibited by the inhibitors of the phosphatidylinositol 3-kinase/Akt pathway. Our results led us to the conclusion that gemcitabine induced cell death through mitophagy with the loss of mtDNA. These findings may provide a rationale for the combination of mtDNA damage with mitophagy in future clinical applications for cancer cells.

Induction of necrosis in human liver tumor cells by α-phellandrene

α-Phellandrene (α-PA) is a component of dietary spices and herbs. The effect of α-PA on anticancer is unclear. This study aims to investigate the effects of α-PA on liver tumor cell death fate. Human liver tumor (J5) cells were incubated with α-PA and analyzed for cell cycle distribution, expression of Bax, Bcl-2, poly (ADP-ribose) polymerase (PARP) protein, and caspase-3 activity of J5 cells, and levels of nitric oxide (NO) production, lactate dehydrogenase (LDH) leakage, and ATP depletion were also analyzed in this study. Results found that α-PA significantly (P < 0.05) decreased the cell viability of J5 cells after 24-h treatment. The cell cycle distribution, Bax, Bcl-2, PARP protein levels, and caspase-3 activity of J5 cells did not change for 24 h after treatment with 30 μM α-PA. Reactive oxygen species levels significantly increased, mitochondrial membrane potential levels significantly decreased when J5 cells were treated with 30 μM α-PA for 24 h (P < 0.05). Thirty μM α-PA significantly (P < 0.05) increased the necrotic cell number, NO production, LDH leakage, and ATP depletion after 24 h of incubation. These results suggest that α-PA induced J5 cell necrosis but not apoptosis, and α-PA-induced necrosis possibly involved ATP depletion.

Involvement of phosphatidylinositol 3-kinase/Akt pathway in gemcitabine-induced apoptosis-like cell death in insulinoma cell line INS-1

This study demonstrated gemcitabine-induced cytotoxicity in the insulinoma cell line INS-1. Gemcitabine inhibited INS-1 cell proliferation and maintained consistent cell number for 24 h, and then caused apoptosis within 48 h of incubation. Since gemcitabine activates the phosphatidylinositol 3-kinase (PI3-K)/Akt pathway, which is involved in the resistance of pancreatic exocrine cancer to gemcitabine, we investigated the participation of this pathway in gemcitabine-induced cytotoxicity in INS-1 cells. LY294002 and wortmannin, two PI3-K inhibitors, significantly prevented gemcitabine-induced cytotoxicity in INS-1 cells, indicating that the PI3-K/Akt pathway is involved in gemcitabine-induced cytotoxicity. Gemcitabine-induced Akt phosphorylation in INS-1 cells was prevented by LY294002. Although gemcitabine induced cell cycle arrest at the G1 and early S phases, LY294002 did not inhibit the cell cycle. These data suggest that PI3-K activation does not influence gemcitabine-induced cell cycle arrest. In gemcitabine-treated cells, nuclear fragmentation and DNA ladder formation were observed. These findings suggest that gemcitabine induced apoptotic cell death in INS-1 cells through the activation of the PI3-K/Akt pathway.

Synergistic antitumor effect of melatonin with several chemotherapeutic drugs on human Ewing sarcoma cancer cells: potentiation of the extrinsic apoptotic pathway

Ewing sarcoma, the second most frequent bone cancer type, affects mainly adolescents, who have a survival of 50% 5 yr after diagnosis. Current treatments include a combination of surgery, radiotherapy and chemotherapy, which present potential serious side effects. Melatonin, a natural molecule without relevant side effects, has been previously shown to induce cytotoxicity in SK-N-MC cells, a Ewing sarcoma cell line. Here, we found that there is a synergy in the antitumor effect when melatonin (50 mum-1 mm) is combined with vincristine at the concentration of 5-10 nm or with ifosfamide at the range of 100 mum-1 mm. This synergism is due to the potentiation of cell death, particularly to the potentiation of apoptosis, i.e., mainly the extrinsic apoptotic pathway. There is a significant increase in the activation of caspase-3, -8, -9 and Bid when melatonin is combined with vincristine or ifosfamide compared to the individual treatments. Finally, there is also a potentiation of the early free radical production, likely dependent on the extrinsic apoptosis pathway activation, when the drugs are combined with melatonin. Other proteins which are related to this pathway including mitogen-activated protein kinase or protein kinase B/Akt are not involved in apoptosis induced by these agents separately or when combined. The results shown here together with the facts that: (i) no relevant side effects have been reported for melatonin and (ii) melatonin has a cytoprotective effect on noncancer cells, opens the door for a new approach in the treatment of the Ewing sarcoma family of tumors.

Ifosfamide nephrotoxicity in children: a mechanistic base for pharmacological prevention

The antineoplastic drug ifosfamide (IFO) in the treatment of solid tumors, particularly in children, is the cause of severe nephrotoxicity. Although it is a potent and effective chemotherapeutic agent, the associated nephrotoxicity has a serious impact on the health and the quality of life of exposed children. The toxic metabolite of IFO thought to be responsible for IFO-induced kidney damage is chloroacetaldehyde (CAA). Those suffering from nephrotoxicity typically develop tubular and glomerular toxicities, with the most severe form being Fanconi's syndrome. As the mode of toxicity of CAA seems to be primarily owing to oxidative stress, the use of antioxidants as a protective measure for the kidneys is a promising strategy. In this review, we highlight recent research that supports the local renal production of CAA as the proximate cause of IFO-induced nephrotoxicity with age as an important risk factor, those under the age of three being the most vulnerable. Most importantly, we focus on the potential advantages of the antioxidant N-acetylcysteine owing to both its antioxidant properties and its current use clinically in pediatrics.