Chemopreventive effects of a new benzo indole derivative against colon cancer / Fatemeh Hajiaghaalipour

Fatemeh , Hajiaghaalipour (2018) Chemopreventive effects of a new benzo indole derivative against colon cancer / Fatemeh Hajiaghaalipour. PhD thesis, University of Malaya.

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Abstract

Colorectal cancer is the third most common form of cancer in both genders in the world. A new synthetic compound, 2-(1,1-dimethyl-1H-benzo[e]indol-2-yl)-3-((2-hydroxyphenyl)amino)acrylaldehyde, abbreviated as DBID was screened its anti-proliferation effect against two colorectal cancer cell lines, and its possible mechanism of action was elucidated. In order to investigate the effect of the DBID compound on the azoxymethane-induced colonic aberrant crypt foci in rats, twenty-four adult male rats were injected subcutaneously with 15 mg/kg per body weight azoxymethane (AOM) once a week for two weeks and were then divided randomly into four groups in this experiment. The rats in cancer and treatments groups received two-month treatment with oral administration of 10% Tween 20 as the vehicle (cancer control), 20 and 40 mg/kg of DBID compound (treated groups), and intraperitoneal injection with 35 mg/kg 5-fluorouracil once a week in the reference control group. The normal control group with no AOM injections were orally administered with 10% Tween 20 for two months (non-cancer control or sham group). On the last day of the experiment, the animals were euthanized and the colon tissues were evaluated grossly and histopathologically for aberrant crypt foci (ACF). The colon tissue homogenate was also evaluated for antioxidant enzyme activities, gene and protein expression. The acute toxicity test and subacute toxicity were used to evaluate the safe usage of DBID compound. In vitro antioxidant activities of the compound were investigated. The DBID compound showed high antioxidant activity in ferric reducing antioxidant power (FRAP) and DPPH radical scavenging assays. It inhibited the proliferation of HCT 116 and HT-29 cells with an IC50 of 9.32, and 11.85 μg/ml and significantly increased the levels of caspase -8, -9 and -3/7 in the treated cells compared to untreated cells. Apoptosis features in HCT 116 and HT-29 cells were detected in treated cells by using flow cytometric analysis of Annexin V and AO/PI staining. The apoptotic changes in expression of caspase were confirmed by gene and protein quantification using RT-PCR and western blot analysis, respectively. The acute toxicity and subacute toxicity studies showed no nephrotoxic and no hepatotoxic effects or any serum biochemical changes in rats. Colon tissue evaluation showed that DBID compound diminished azoxymethane-induced aberrant crypt foci formation and pathological changes in the colonic mucosal tissues. Following treatment with the compound, antioxidant enzyme activity was increased compared to carcinogen groups. Moreover, the downregulation of Bcl2 and upregulation of Bax protein and caspase 3 were confirmed by RT-PCR and western blot. This study has shown that the DBID compound has demonstrated chemotherapeutic activity which was evidenced by significant increases in the expression and activation of caspase and exploits the apoptotic signaling pathways to trigger cancer cell death. There was significant inhibition of azoxymethane-induced colonic aberrant crypt foci formation by a new benzo indole derivative compound in rats that might be associated with its potent antioxidant activity and effective activity against free radicals involved in the formation of colorogenic lesions followed by alteration of the expression of apoptotic genes.

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