High overexpression of fatty acid synthase is associated with poor survival in Chinese patients with gastric carcinoma

Abstract

Fatty acid synthase (FAS) is the key enzyme regulating de novo biosynthesis of fatty acids. FAS overexpression has been found in many types of tumors and is associated with poor survival. However, the expression of FAS and its relationship with prognosis in Chinese patients with gastric carcinoma are still unknown. Therefore, in this study, we examined the expression of FAS using tissue microarrays and determined its correlation with clinicopathological characteristics and prognosis of gastric carcinoma in Chinese patients. FAS overexpression was graded as S (T/A) <1, ≥1 to <2, ≥2 to <3 or ≥3 in 35 (38.9%), 20 (22.2%), 9 (10%) and 26 (28.9%) patients, respectively. High FAS overexpression [S (T/A) ≥3] was significantly correlated with poor prognosis (log-rank test, P= 0.0078) and with decreased 3-year survival rate (χ(2) test, P=0.0023). FAS overexpression was not significantly associated with other clinicopathological characteristics. In conclusion, our results suggest that FAS expression might be a potential prognostic marker for gastric carcinoma in Chinese patients.

Figure 1

Immunohistochemical expression of FAS in gastric carcinomas. (A) Representative tissue microarray. The odd and even lines represent tumor and adjacent normal tissue samples, respectively. (B) Representative cases of immunohistochemical expression of FAS for S (T/A) ≥1 to <2, S (T/A) ≥2 to <3 and S (T/A) ≥3. S (T/A) = immunohistochemistry score (tumor)/immunohistochemistry score (adjacent tissue). Immunohistochemistry score = staining intensity x percent of FAS-positive cells. Staining intensity was scored as 0, negative; 1, weak; 2, moderate; and 3, high.

Figure 2

(A) Scatter plot showing the distribution of the immunohistochemical (IHC) score for FAS expression in gastric tumor tissues and adjacent normal tissues. The mean IHC scores for FAS expression in tumors and adjacent tissues are 1.065±0.099 and 0.7981±0.074, respectively. The P-value was determined by an unpaired test. (B) Distribution of FAS expression defined as S (T/A). Overall, 38.9% (35/90), 22.2% (20/90), 10% (9/90) and 28.9% (26/90) of the carcinoma tissue specimens were classified as S (T/A) ≥0 to <1, S (T/A) ≥1 to <2, S (T/A) ≥2 to <3 and S (T/A) ≥3, respectively.

Figure 3

The highest level of FAS overexpression is associated with poor survival of patients with gastric carcinoma. (A–C) show survival curves for patients with carcinomas classified as S (T/A) ≥1, ≥2 and ≥3, respectively. FAS overexpression corresponding to S (T/A) ≥1 or ≥2 was not associated with survival. Patients with S (T/A) ≥3 had significantly worse overall survival compared with all other patients (log-rank test, P=0.0078).