Immobilization of native and poly(ethylene glycol)‐treated (‘PEGylated’) bovine serum amine oxidase into a biocompatible hydrogel

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Abstract. Hyperthermia is currently receiving widespread attention when associated with other therapeutic modalities, such as irradiation or chemotherapy, in the treatment of cancer. The occurrence of resistance to cytotoxic pharmacological agents in tumor cells, associated with several phenotypic alterations, is one of the major obstacles to successful anticancer chemotherapy. We investigated a new strategy to overcome multidrug resistance (MDR) cancer cells, using bovine serum amine oxidase (BSAO), which forms toxic products from spermine (H 2 O 2 and aldehydes). The cytotoxicity of the products was evaluated in drug-sensitive (LoVo WT) and multidrug-resistant (LoVo DX) colon adenocarcinoma cells at 37 and 42˚C, using a clonogenic cell survival assay. Cytotoxicity was considerably enhanced at 42˚C. Both toxic species contributed to the thermal enhancement of cytotoxicity induced by BSAO and spermine. Cytotoxicity was eliminated in the presence of catalase and aldehyde dehydrogenase (ALDH). An interesting finding was that BSAO and spermine at <1 μM, which were non toxic at 37˚C, became cytotoxic at 42˚C and resemble thermosensitizers. Cell survival results and electron microscopy investigations suggest that, at 42˚C, LoVo DX cells are not resistant to the cytotoxic enzymatic oxidation products of spermine, as was already demonstrated in these cells at 37˚C. Moreover, microscopy modifications caused by both toxic products were more pronounced in LoVo DX than in LoVo WT cells, where morphological cytoplasmatic alterations were shown. Our findings suggest that hyperthermia combined with the enzymatic toxic oxidation products of spermine might be a promising anticancer strategy, mainly against MDR tumor cells.

Section: Discussionmentioning

confidence: 76%

Hyperthermia enhances cytotoxicity of amine oxidase and spermine on drug-resistant LoVo colon adenocarcinoma cells

Agostinelli¹,

Belli²,

Vedova³

et al. 2006

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“…The enzyme was administered in its native form and also immobilized in a biocompatible polymer composed of bovine serum albumin and polyethylene glycol (PEG). The immobilized enzyme showed higher operational stability and functional activities, relative to its native form (52). When immobilized BSAO was injected into the tumor, there was a marked decrease (70%) in tumor growth, compared to a lower decrease of 32% of tumor size when native BSAO was administered.…”

Section: Induction Of Apoptosis Directly By Polyaminesmentioning

confidence: 97%

Mechanism of cell death induced by spermine and amine oxidase in mouse melanoma cells

Averill‐Bates¹,

Ke²,

Tanel³

et al. 2008

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Abstract. Polyamines such as spermine, spermidine and putrescine are necessary for cell proliferation and are detected at higher concentrations in most tumor tissues, compared to normal tissues. The amine oxidase enzymes can generate cytotoxic products such as hydrogen peroxide and aldehydes from these polyamines. This study investigates the mechanisms of cell death in B16-F0 mouse melanoma tumor cells exposed to bovine serum amine oxidase and exogenous spermine. The bovine serum amine oxidase/spermine enzymatic system induced inhibition of cell proliferation in B16-F0 melanoma cells and cell death by both apoptotic and necrotic processes. Bovine serum amine oxidase or spermine, alone, did not induce cytotoxicity or cell death by apoptosis, indicating that the enzymatic reaction products were responsible. Catalase and NAD-dependent aldehyde dehydrogenase, inhibitors of hydrogen peroxide and aldehydes, respectively, decreased cell death by apoptosis and necrosis. This further confirms that the cytotoxic products are responsible for causing cell death. Use of inhibitors of different caspases showed that melanoma cells were sensitive to processes involving caspase-3 and -9, but were insensitive to caspase-6. Bovine serum amine oxidase in the presence of spermine could be useful as a promising new tool for anticancer treatment by the selective generation of toxic compounds from polyamines in tumors.

“…For the slow release of toxic spermine metabolites in tumors, the use of BSAO conjugated to biocompatible polymers has been considered (4,20). The high polyamine content of tumor cells and the release of polyamines from damaged cells may make the administration of spermine superfluous in therapeutic application.…”

Section: Discussionmentioning

confidence: 99%

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

Agostinelli

Vedova²,

Belli³

et al. 2006

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Abstract.The in situ formation of cytotoxic metabolites by an enzyme-catalyzed reaction is a recent approach in cancer therapy. The present results show that multidrug-resistant human colon adenocarcinoma cells (LoVo) are significantly more sensitive than corresponding wild-type cells to hydrogen peroxide and aldehydes, the products of bovine serum amine oxidase (BSAO)-catalyzed oxidation of spermine. Pretreatment of the cells with N 1 ,N 4 -bis(2,3-butadienyl)-1,4-butanediamine (MDL 72527), a lysosomotropic compound, sensitized both cell lines to the subsequent exposure to spermine metabolites, as was evident from the decrease of cell survival by a log unit. The sensitizing effect was greater in the case of the multidrug-resistant cell line, an aspect of particular importance with respect to potential therapeutic applications of the method, since conventional cancer therapy suffers from the development of drug resistance. Cell viability was determined using a clonogenic assay. MDL 72527 (at 300 μM) produced numerous cytoplasmic vacuoles, presumably of lysosomal origin, after 6-h exposure, which decreased in size and number (in the presence of the drug) by 24 h and had almost disappeared completely at 48 h. Mitochondrial damage, as observed by transmission electron microscopy, seemed to correlate better with the cytotoxic effects of the treatment than the formation of vacuoles. We suggest that the release of lysosomal enzymes into the cytosol by MDL 72527 is the main reason for its sensitizing effect. It is known that lysosomotropic compounds, which release lysosomal enzymes, produce oxidative stress and apoptosis.