Expression profile of polyunsaturated fatty acids in colorectal cancer.

AIM: To investigate the relationship between the metabolism of polyunsaturated fatty acids (PUFAs) and tumor-associated factors for predicting the outcome of colorectal carcinoma (CRC) in Chinese patients. METHODS: Fresh-frozen malignant and normal tissues from 82 Chinese patients with CRC were analyzed for PUFA composition using gas-liquid chromatography. The levels of vascular endothelial growth factor (VEGF), cyclooxygenase-2 (COX-2), prostaglandin E2 and platelet-derived growth factor (PDGF) were measured by enzyme-linked immunosorbent assay, and the levels of VEGF, p53 and Ki-67 were measured by immunohistochemistry. RESULTS: In malignant tissue, compared with normal tissue, the levels of total omega-6 PUFAs (24.64% +/- 3.41% vs 26.77% +/- 3.37%, P = 0.00) and linoleic acid (LA) (15.46% +/- 3.51% vs 18.30% +/- 2.83%, P < 0.01) were lower, whereas the levels of total omega-3 PUFAs (1.58% +/- 0.74% vs 1.35% +/- 0.60%, P < 0.01) and dihomo-gamma-linolenic acid (DGLA) (1.32% +/- 0.69% vs 0.85% +/- 0.29%, P < 0.01) were significantly higher. The ratios of arachidonic acid (AA)/LA (0.53 +/- 0.22 vs 0.42 +/- 0.19, P < 0.01) and AA/total omega-6 PUFAs (0.31 +/- 0.09 vs 0.27 +/- 0.10, P < 0.01) were also significantly higher in malignant tissue. The levels of PDGF (353.10 +/- 148.85 pg/mL vs 286.09 +/- 104.91 pg/mL, P < 0.01), COX-2 (125.21 +/- 70.29 ng/mL vs 67.06 +/- 42.22 ng/mL, P < 0.01) and VEGF (357.11 +/- 128.76 pg/mL vs 211.38 +/- 99.47 pg/mL, P < 0.01) were also higher in malignant tissue compared to normal tissue. COX-2 was inversely correlated with LA (R = -0.3244, P < 0.05) and positively correlated with AA/total.-6 PUFAs (R = 0.3083, P < 0.05) and AA/LA (R = 0.3001, P < 0.05). The tissue level of LA was highest in poorly differentiated tumors (19.9% +/- 6.3%, P < 0.05), while the ratio of AA/omega-3 PUFAs was lowest in these tumors (10.8 +/- 2.6, P < 0.05). In VEGF-positive tumors, the level of LA was higher (16.2% +/- 3.7% vs 13.9% +/- 2.7%, P < 0.01), while the AA/omega-3PUFA, AA/omega-6 PUFA, and AA/LA ratios were lower than in VEGF-negative tumors (5.0 +/- 1.8 vs 6.7 +/- 3.3, 0.30 +/- 0.09 vs 0.34 +/- 0.09, 0.50 +/- 0.21 vs 0.61 +/- 0.21, P < 0.01). CONCLUSION: The metabolism of PUFAs may play an important role in the evolution of inflammation-driven tumorigenesis in CRC and may be considered a potential marker for prognosis.