Is Curcumin a Chemopreventive Agent for Colorectal Cancer?

Protective role of a melon superoxide dismutase combined with gliadin (GliSODin) on the status of lipid peroxidation and antioxidant defense against azoxymethane-induced experimental colon carcinogenesis

Background

Azoxymethane (AOM) is a potent carcinogenic agent commonly used to induce colon cancer in rats and mice, with the cytotoxicity of AOM mediated by oxidative stress.

Aim of Study

This study investigated the protective effect of a natural antioxidant (GliSODin) against AOM-induced oxidative stress and carcinogenesis in rat colon.

Methods

Twenty male Wistar rats were randomly divided into four groups (five rats/group). The control group was fed a basal diet. AOM-treated group (AOM) was fed a basal diet and received intraperitoneal injections of AOM for 2 weeks at a dose of 15 mg/kg. The GliSODin treatment group (superoxide dismutase [SOD]) received oral supplementation of GliSODin (300 mg/kg) for 3 months, and the fourth combined group received AOM and GliSODin (AOM + SOD). All animals were continuously fed ad libitum until the age of 16 weeks when all rats were sacrificed. The colon tissues were examined microscopically for pathological changes and aberrant crypt foci (ACF) development, oxidant status (lipid peroxidation-LPO), and enzyme antioxidant system (glutathione [GSH], GSH-S-transferase, catalase, and SOD).

Results

Our results showed that AOM induced ACF development and oxidative stress (GSH depletion and lipid peroxidation) in rat colonic cells. The concomitant treatment of AOM with GliSODin significantly ameliorated the cytotoxic effects of AOM.

Conclusion

The results of this study provide in vivo evidence that GliSODin reduced the AOM-induced colon cancer in rats, through their potent antioxidant activities.

A Comprehensive Review of the Use of Antioxidants and Natural Products in Cancer Patients Receiving Anticancer Therapy

Cancer is the leading cause of mortality and morbidity worldwide. The side effects of cancer treatment affect the quality of life. Cancer patients search for antioxidant dietary supplements and natural products during or after conventional cancer treatment for the alleviation of side effects, improvement of the benefits of treatment, and promotion of well-being. However, the efficacy and safety of these products remain controversial; moreover, previous data do not support the standardized use of those alternative treatments in clinics. The current study reviewed the manuscripts reporting the administration of antioxidants and natural products during cancer treatment and revised preclinical and clinical studies on various types of cancer. Most of the positive results were obtained from experimental animal models; however, human clinical studies are discouraging in this regard. Therefore, further precise and distinguishable studies are required regarding antioxidant dietary supplementation. Future studies are also needed to clarify dietary supplements' mechanism of action and pharmacokinetics in a suitable cancer patient population that will benefit the therapeutic regimens. Despite the popularity of dietary supplements, clinicians and patients should always consider their potential benefits and risks. Patients should discuss with their physician before taking any dietary antioxidant supplements or natural products.

Polyphenols in Colorectal Cancer: Current State of Knowledge including Clinical Trials and Molecular Mechanism of Action. Biomed Res Int. 2018;2018:4154185. [PMID: 29568751 PMCID: PMC5820674 DOI: 10.1155/2018/4154185]

Polyphenols have been reported to have wide spectrum of biological activities including major impact on initiation, promotion, and progression of cancer by modulating different signalling pathways. Colorectal cancer is the second most major cause of mortality and morbidity among females and the third among males. The objective of this review is to describe the activity of a variety of polyphenols in colorectal cancer in clinical trials, preclinical studies, and primary research. The molecular mechanisms of major polyphenols related to their beneficial effects on colorectal cancer are also addressed. Synthetic modifications and other future directions towards exploiting of natural polyphenols against colorectal cancer are discussed in the last section.