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Toxicol In Vitro. 2016 Apr;32:8-15. doi: 10.1016/j.tiv.2015.12.001. Epub 2015 Dec 8.

Superoxide-hydrogen peroxide imbalance interferes with colorectal cancer cells viability, proliferation and oxaliplatin response.

Author information

1
Programa de Pós-Graduação em Farmacologia, Centro de Ciências da Saúde, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
2
Programa de Pós-Graduação em Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
3
Universidade Federal de Ciências da Saúde de Porto Alegre, Brazil.
4
BIOREP Lab, Centro de Ciências Agrárias, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil.
5
Programa de Pós-Graduação em Farmacologia, Centro de Ciências da Saúde, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil; Programa de Pós-Graduação em Bioquímica Toxicológica, Centro de Ciências Naturais e Exatas, Universidade Federal de Santa Maria, Santa Maria, RS, Brazil. Electronic address: ibmcruz@hotmail.com.

Abstract

The role of superoxide dismutase manganese dependent enzyme (SOD2) in colorectal cancer is presently insufficiently understood. Some studies suggest that high SOD2 levels found in cancer tissues are associated with cancer progression. However, thus far, the role of colorectal cancer superoxide-hydrogen peroxide imbalance has not yet been studied. Thus, in order to address this gap in extant literature, we performed an in vitro analysis using HT-29 colorectal cell line exposed to paraquat, which generates high superoxide levels, and porphyrin, a SOD2 mimic molecule. The effect of these drugs on colorectal cancer cell response to oxaliplatin was evaluated. At 0.1 μM concentration, both drugs exhibited cytotoxic and antiproliferative effect on colorectal cancer cells. However, this effect was more pronounced in cells exposed to paraquat. Paraquat also augmented the oxaliplatin cytotoxic and antiproliferative effects by increasing the number of apoptosis events, thus causing the cell cycle arrest in the S and M/G2 phases. The treatments were also able to differentially modulate genes related to apoptosis, cell proliferation and antioxidant enzyme system. However, the effects were highly variable and the results obtained were inconclusive. Nonetheless, our findings support the hypothesis that imbalance caused by increased hydrogen peroxide levels could be beneficial to cancer cell biology. Therefore, the use of therapeutic strategies to decrease hydrogen peroxide levels mainly during oxaliplatin chemotherapy could be clinically important to the outcomes of colorectal cancer treatment.

KEYWORDS:

Chemotherapy; HT-29 colorectal cell; Paraquat; Porphyrin; Superoxide dismutase manganese dependent

PMID:
26674755
DOI:
10.1016/j.tiv.2015.12.001
[Indexed for MEDLINE]
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