Relations of transforming growth factor-beta1 expression to differentiation and prognosis of advanced gastric cancer

Abstract

To clarify the correlation of transforming growth factor-beta1 (TGF-beta1) expression with the differentiation and prognosis of advanced gastric cancer (GC). Whole genome expression chip hybridization, was used to detect the expression of TGF-beta1 and TGF-betaR1 in 20 specimens of intestinal-type GC and para-cancer tissues. RT-PCR and immunohistochemistry (IHC) analysis were used to detect the mRNA and protein expression of TGF-beta1 and TGF-betaR1 in 30 specimens of intestinal-type GC tissue and para-cancer tissues. The mixture of gastric mucosa tissues from 20 non-tumor patients was used as common reference. The expression level of TGF-beta1 and TGF-betaR-1 genes was higher in the GC tissues than in the para-cancer tissues. However, the expression of Smad gene family was not significantly different between the GC tissues and para-tumor normal tissues. TGF-beta1 gene expression and TGF-betaR1 gene expression were higher in the GC tissues. RT-PCR showed that both TGF-beta1 and TGF-betaR-1 genes were highly expressed in the mRNA level in 21 of the 30 CC patients IHC showed that TGF-beta1 protein was expressed mainly in the cytoplasm. 32 of the 90 specimens of GC tissue were highly positive in TGF-beta1 protein (64%), in comparison with the positive rate of 5% (1/20) in the para-cancer normal tissues. The TGF-beta1 protein expression rate of the highly and moderately differentiated GC tissues was 59% (59%, 23/39), significantly higher than that of the lowly differentiated GC tissues (18%, 9/51, P < 0.01). IHC showed that the TGF-beta R-I rate was 57% (42/74) in the well differentiated specimens, particularly 68% (26/38) in the highly differentiated specimens, and was 44% in the poorly differentiated GC (6/20, P < 0.05). Log rank test showed that the prognosis of the patients positive in TGF-beta1 was significantly better than those negative in TGF-beta1 (P = 0.0058). However, the survival rate did not differ significantly according to TGF-beta R-I expression (P = 0.8453). TGF-beta1 expression is significantly correlated with the differentiation degree of GC. Moreover, positive expression of TGF-beta1 is a favorable prognostic factor in advanced GC. Expression of TGF-beta1 may be an important preoperative prognostic variable for advanced GC.