Mitochondrial alterations induced by serum amine oxidase and spermine on human multidrug resistant tumor cells

Abstract

Multidrug resistance (MDR) has been studied extensively because it is one of major problems in cancer chemotherapy. The MDR phenotype is often due to overexpression of P-glycoprotein (P-gp), that acting as an energy-dependent drug efflux pump exports various anticancer drugs out of cells. The major goal of our investigation is to establish whether bovine serum amine oxidase (BSAO), which generates the products H(2)O(2) and aldehyde(s), from the polyamine spermine, is able to overcome MDR of human cancer cells. The cytotoxicity of the products was evaluated in both drug-sensitive (LoVo WT) and drug-resistant (LoVo DX) colon adenocarcinoma cells. A clonogenic cell survival assay demonstrated that LoVo DX cells were more sensitive than LoVo WT cells. Exogenous catalase protected cells against cytotoxicity mainly due to the formation of H(2)O(2). However, spermine-derived aldehyde(s) still induced some cytotoxicity. The cytotoxic effect was totally inhibited in the presence of both enzymes, catalase and NAD-dependent aldehyde dehydrogenase (ALDH). Transmission electron microscopy investigations showed that BSAO and spermine induced evident mitochondria alterations, more pronounced in MDR than in LoVo WT cells. The mitochondrial activity was checked by flow cytometry studies, labelling cells with the probe JC1, that displayed a basal hyperpolarized status of the mitochondria in multidrug-resistant cells. After treatment with amine oxidase in the presence of polyamine-spermine, the cells showed a marked increase in mitochondrial membrane depolarization higher in LoVo DX than in LoVo WT cells. Our findings suggest that toxic oxidation products formed from spermine and BSAO could be a powerful tool in the development of new anticancer treatments, mainly against MDR tumor cells.

Reactive oxygen species spermine metabolites generated from amine oxidases and radiation represent a therapeutic gain in cancer treatments

“…In addition, our findings also showed that ROS formed by the combination BSAO/spermine are not only able to prevent tumor cell growth, but also prevents mass tumor growth. MDR mitochondrial damage observed by mitochondrial membrane depolarization and transmission electron microscopy (TEM) was attributed to the cytotoxic effects induced by ROS, generated during the treatment, aldehyde(s) also contributed to cytotoxicity, but at a later stage of the reaction and to a lesser extent (~20%), as demonstrated in the presence of aldehyde dehydrogenase (12,13,34). In the present study, we further confirmed these results by real-time PCR experiments.…”

“…Increasing interest has been posed on the SPM amino oxidase (SMOX) and BSAO enzyme activities, since SPM catabolic degradation has been found closely related to DNA oxidation and apoptosis, mainly via hydrogen peroxide (H 2 O 2 ) production (12)(13)(14)(15). High SMOX activity provokes low level of SPM and the inhibition of the interactions with DNA, thus causing sensitivity to ionizing radiation exposure and cell death (15,16 (13,20) and in vivo many tumors appear resistant to oxidative stress and apoptosis, we dissected the influence of chronic sub-lethal DNA damage and DNA repair by mSMOX ectopically overexpressed in proficient Chinese hamster AA8 cell line and both deficient base-excision-repair (BER) EM9 (21) and transcriptioncoupled nucleotide-excision-repair (NER) UV61 (22) cell lines to represent cellular models of priming damage dose of ROS. Low doses of X-irradiation delivers challenging dose of damage evaluated at 6 and 24 h after exposure.…”

Cytotoxicity of spermine oxidation products to multidrug resistant melanoma M14 ADR2 cells: Sensitization by the MDL 72527 lysosomotropic compound

“…Instead, the ultrastructural alterations observed in mitochondria appear to correlate better with the cytotoxic effects induced by BSAO/spermine treatment. In agreement with this finding is the fact that mitochondria-mediated toxic effects are among the early events (13,48).…”

“…However, P-gp-mediated excretion of the toxic products of spermine oxidation appears to play no, or only a minor role, because M14 ADR2 cells were not less, but significantly more sensitive to exposure to BSAO and spermine than M14 WT cells. The higher sensitivity to cytotoxic spermine derivatives of colon adenocarcinoma LoVo DX cells, as compared with WT cells, has previously been attributed to an earlier and higher mitochondrial membrane depolarisation, and a higher basal production of ROS that was not related to the glutathione content, because MDR and WT LoVo cells have the same glutathione pool (13,48). At present no data exist to allow to draw the same conclusion on M14 melanoma cells, although the same physiological factors are possibly responsible for the enhanced sensitivity in both MDR cell lines.…”

Sensitization of human colon adenocarcinoma cells (LoVo) to reactive oxygen species by a lysosomotropic compound

“…Formation of hydrogen peroxide by the xanthine oxidase reaction within a muscle also had an anti-tumor effect (5). Other experiments demonstrated that multidrug resistant (MDR) LoVo cells (obtained by exposure to doxorubicin) (6) are more sensitive to toxic spermine metabolites than their wild-type counterparts (3,7).…”