Luteolin, a bioflavonoid inhibits azoxymethane-induced colon carcinogenesis: Involvement of iNOS and COX-2

Abstract

Colon cancer (CRC) is a serious health problem through worldwide. Development of novel drug without side effect for this cancer was crucial. Luteolin (LUT), a bioflavonoid has many beneficial effects such as antioxidant, anti-inflammatory, anti-proliferative properties. Azoxymethane (AOM), a derivative of 1, 2-Dimethyl hydrazine (DMH) was used for the induction of CRC in Balb/C mice. CRC was induced by intraperitoneal injection of AOM to mice at the dose of 15 mg/body kg weight for 3 weeks. Mouse was treated with LUT at the dose of 1.2 mg/body kg weight orally until end of the experiment. The expression of inducible nitric oxide synthase (iNOS) and cyclooxygense (COX)-2 were analyzed by RT-PCR and immunohistochemistry. The expressions of iNOS and COX-2 were increased in the case of AOM induction. Administration of LUT effectively reduced the expressions of iNOS and COX-2. The present study revealed that, LUT suppresses both iNOS and COX-2 expressions and act as an anti-inflammatory role against CRC.

Keywords: Azoxymethane; COX-2; Luteolin; colon cancer; iNOS.

Figure 1

Luteolin reduced the levels of ALP and LDH Units: (A): Activity of ALP (mU/mg protein), (B): activity of LDH (μM of pyruvate liberated/min/mg protein). Values are expressed as mean ± S.D. for 6 mice in each group. ^aControl Vs AOM, ^bAOM Vs AOM+LUT, ns-non significant P <0.05

Figure 2

Luteolin decreases the expression of iNOS (a): (Control) Normal expression of iNOS, (b): (AOM) high expression of iNOS (brown color) was observed, (c): (AOM+LUT) lesser degree of expression of iNOS was noticed, (d): (LUT) Expression was similar to that of control. -> shows the expression of iNOS. (2B), Quantification of the expressions of iNOS. Values are expressed as mean ± S.D. Comparisons: ^aControl Vs AOM, ^bAOM Vs AOM+LUT, ns-non significant *P < 0.05. (2C): RT-PCR analysis of iNOS. The band was detected at the 194 bp and Actin was at 842 bp. The quantification of iNOS was normalized with Actin shown in 2D

Figure 3

Luteolin decreases the expression of COX-2 (a): (Control) Normal expression of COX-2, (b): (AOM) high expression of COX-2 (brown color) was observed, (c): (AOM+LUT) lesser degree of expression of COX-2 was noticed, (d): (LUT) Expression was similar to that of control. -> indicates the expression of COX-2 protein. (3B): Quantification of the expression of COX-2. Values are expressed as mean ± S.D. Comparisons: ^aControl Vs AOM, ^bAOM Vs AOM+LUT, ns-non significant *P < 0.05. (2C): RT-PCR analysis of COX-2. The band was detected at the 247 bp and Actin was at 842 bp. The quantification of COX-2 was normalized with Actin shown in 3D