LLLT enhance cyclophosphamide induced TRPM2 channel activation in human colon cancer cells.

AIM: Transient receptor potential (TRP) channels expression is enhanced significantly in colon cancer cells and  Low Lever Laser Treatment (LLLT), is known to have effects and is used clinically in the treatment ofmany diseases, including colon cancer. We aimed to reveal the effects of (LLLT) on apoptosis of colon cancer and on the efficacy of cyclophosphamide via Transient receptor potential melastatin 2 (TRPM2) channels. METHOD: Human colon cancer cells (Caco-2) were cultured and cells were divided into seven main groups. Cells were incubated with cyclophosphamide, TRPM2 channel inhibitor, stimulator and low level laser exposure separately and together. The effects of cyclophosphamide and low level laser were investigated on apoptosis. RESULTS: It was found that the levels of apoptosis in cyclophosphamide group were significantly increased in cancer cells compared to the control group. TRPM2 channel stimulator administration resulted in significantly increased apoptosis levels compared to the control group, in cyclophosphamide + low level laser group the apoptosis level was significantly increased compared to the cyclophosphamide-only group. CONCLUSIONS: It has been shown that apoptotic effects of cyclophosphamide on colon cancer cells were directly related to TRPM2 channels, low level laser increased apoptosis in colon cancer cells through TRPM2 channels and induced apoptotic effect of cyclophosphamide (Fig. 5, Ref. 26).

The role of selenium in bevacizumab induced cardiotoxicity.

OBJECTIVE: We investigated the role of selenium in bevacizumab induced cardiotoxicity and involvement of transient receptor potential vanilloid 1 (TRPV1) channels in cardiomyocytes. MATERIALS AND METHODS: All cells (Human cardiomyocyte cell line) were cultured at 37 °C. We divided the cells into seven groups as control, bevacizumab, bevacizumab + capsazepin, bevacizumab + selenium, bevacizumab + selenium + capsazepin, selenium and selenium + capsazepin groups. Cells in the groups were stimulated with capsaicin and inhibited with capsazepin in related experiments for activation and inactivation of TRPV1 channels, respectively. RESULTS: Cytosolic calcium, apoptosis and intracellular ROS production levels were lower in bevacizumab + selenium group than in the bevacizumab group of cardiomyocytes (p ˂ 0.001). Also, values were markedly lower in the bevacizumab + selenium + capsazepine group when compared to the bevacizumab + selenium group (p ˂ 0.001). CONCLUSION: We found that cytosolic calcium, apoptosis, intracellular ROS production levels were increased in bevacizumab induced cardiotoxicity and selenium treatment could have beneficial effects on these parameters (Fig. 5, Ref. 51).

The effect of melatonin on digoxin­induced cardiac damage in cardiomyocytes.

OBJECTIVES: Digoxin is a cardiac glycoside which is widely used in cardiovascular medicine. Oxidative stress, as well as intracellular Ca2+ overload, plays an important role in digoxin toxicity. Transient receptor potential vanilloid 1 (TRPV1) channels are found in cardiomyocyte cells and they are activated by reactive oxygen species. We investigated the effects of digoxin toxicity and alterations in Ca2+ influx, oxidative stress and apoptosis through TRPV1 channels and modulator role of melatonin in cardiomyocytes. METHODS: The cells were divided into seven main groups as control, digoxin, digoxin+capsazepine, digoxin+melatonin, digoxin+capsazepine+melatonin, melatonin and melatonin+capsazepine groups. Cells in the groups were stimulated with capsaicin and inhibited with capsazepine in related experiments for activation and inactivation of TRPV1 channels, respectively. We measured cytosolic calcium, intracellular reactive oxygen, mitochondrial depolarization, caspase 9 and caspase 3 levels. RESULTS: The apoptosis values were significantly lower in the melatonin and digoxin+melatonin groups than in the digoxin group of cardiomyocytes (p < 0.001). The cell viability values were higher in the digoxin+capsazepine (p < 0.001), digoxin+melatonin (p < 0.001) and digoxin+melatonin+capsazepine (p < 0.001) groups than in the digoxin group. CONCLUSION: TRPV1 channels are overactivated during digoxin toxicity and melatonin could show a cardioprotective effect through TRPV1 channel modulation (Fig. 5, Ref. 56).

Synergic and comparative effect of 5-fluorouracil and leucoverin on breast and colon cancer cells through TRPM2 channels.

OBJECTIVES: We aimed to reveal the role of 5-fluorouracil (5-FU) and Leucovorin (LV) along with transient receptor potential protein melastatin 2 (TRPM2) channels in breast and colon cancer cells during the treatment process. BACKGROUND: 5-FU and LV are widely used in breast and colon cancers for chemotherapy. It has been reported that the expression of TRPM2 channels increased intensively in cancer cells. METHODS: Breast (MCF7) and colon (Caco-2) cells were cultured and divided into seven main groups. The cells in the group were incubated with 5-FU and LV for 24 hrs and then incubated with Antranilic acid. The effects of medicines were investigated on all molecular pathways of apoptosis. RESULTS: It was found that 5FU and LCV, administered separately and together on breast cancer cell culture and colon cancer cell culture increased the intracellular calcium levels by stimulation of TRPM2 channels in both cancer cells. CONCLUSION: As the result of our study, it has been shown that apoptotic effects of 5FU and LV on both colon and breast cancer cells were directly related to TRPM2 channels and that TRPM2 channels played an important role in the whole molecular pathway of apoptosis leading to increased intracellular Ca2+ (Ca2+) levels and increased mitochondrial depolarisation (Fig. 6, Ref. 43).

Involvement of apoptosis and calcium accumulation through TRPV1 channels in neurobiology of epilepsy.

Calcium ion accumulation into the cytosol of the hippocampus and dorsal root ganglion (DRG) are main reasons in etiology of epilepsy. Transient receptor potential vanilloid type 1 (TRPV1) channel is a cation-permeable calcium channel found in the DRG and hippocampus. Although previous studies implicate TRPV1 channels in the generation of epilepsy, suppression of ongoing seizures by TRPV1 antagonists has not yet been investigated. We tested the effects of TRPV1-specific antagonists, capsazepine (CPZ) and 5'-iodoresiniferatoxin (IRTX) on the modulation of calcium accumulation, apoptosis and anticonvulsant properties in the hippocampus and DRG of pentylentetrazol (PTZ) and capsaicin (CAP) administrated rats. Forty rats were divided into five groups as follows; control, PTZ, CAP+PTZ, IRTX, and IRTX+PTZ. Fura-2 and patch-clamp experiments were performed on neurons dissected from treated animals by CAP and CPZ. PTZ and CAP+PTZ administrations increased intracellular free Ca(2+) concentrations, TRPV1 current densities, apoptosis, caspase 3 and 9 values although the values were reduced by IRTX and CPZ treatments. Latency time was extended by application CPZ and IRTX although CAP produced acceleration of epileptic seizures. Taken together, these results support a role for TRPV1 channels in the inhibition of apoptosis, epileptic seizures and calcium accumulation, indicating that TRPV1 inhibition may possibly be a novel target in the DRG and hippocampus for prevention of epileptic seizures and peripheral pain.

Homocysteine and cytosolic GSH depletion induce apoptosis and oxidative toxicity through cytosolic calcium overload in the hippocampus of aged mice: involvement of TRPM2 and TRPV1 channels.

Oxidative stress and apoptosis were induced in neuronal cultures by inhibition of glutathione (GSH) biosynthesis with d,l-buthionine-S,R-sulfoximine (BSO). Transient receptor potential melastatin 2 (TRPM2) and transient receptor potential vanilloid 1 (TRPV1) cation channels are gated by oxidative stress. The oxidant effects of homocysteine (Hcy) may induce activation of TRPV1 and TRPM2 channels in aged mice as a model of Alzheimer's disease (AD). We tested the effects of Hcy, BSO and GSH on oxidative stress, apoptosis and Ca2+ and influx via TRPM2 and TRPV1 channels in the hippocampus of mice. Native mice hippocampal neurons were divided into five groups as follows; control, Hcy, BSO, Hcy+BSO and Hcy+BSO+GSH groups. The neurons in TRPM2 and TRPV1 experiments were stimulated by hydrogen peroxide and capsaicin, respectively. BSO and Hcy incubations increased intracellular free Ca2+ concentrations, reactive oxygen species, apoptosis, mitochondrial depolarization, and levels of caspase 3 and 9. All of these increases were reduced by GSH treatments. Treatment with 2-aminoethoxydiphenyl borate (2-APB) and N-(p-amylcinnamoyl)anthranilic acid (ACA) as potent inhibitors of TRPM2, capsazepine as a potent inhibitor of TRPV1, verapamil+diltiazem (V+D) as inhibitors of the voltage-gated Ca2+ channels (VGCC) and MK-801 as a N-methyl-d-aspartate (NMDA) channel antagonist indicated that GSH depletion and Hcy elevation activated Ca2+ entry into the neurons through TRPM2, TRPV1, VGCC and NMDA channels. Inhibitor roles of 2-APB and capsazepine on the Ca2+ entry higher than in V+D and MK-801 antagonists. In conclusion, these findings support the idea that GSH depletion and Hcy elevation can have damaging effects on hippocampal neurons by perturbing calcium homeostasis, mainly through TRPM2 and TRPV1 channels. GSH treatment can partially reverse these effects.