Transforming growth factor-β1 induces apoptosis in gastric cancer cells through a p53-independent pathway

BACKGROUND. Apoptosis is induced by various anticancer agents or radiation through the tumor suppressor gene p53-dependent pathway and is also induced by other factors, including transforming growth factor-β₁ (TGF-β₁). In this study, the authors investigated whether TGF-β₁ would induce apoptosis in gastrointestinal cancer cells, and its relation to the status of the p53 gene. METHODS. The induction of apoptosis by TGF-β₁ was determined in 12 gastrointestinal cancer cell lines using DNA ladder formation. Status of the p53 gene was examined by sequencing of cDNA from p53 mRNA and expressions of TGF-β₁ mRNA and TGF receptors I and II mRNAs were determined by Northern blot analysis and the reverse transcriptase-polymerase chain reaction analysis, respectively. RESULTS. Of 12 cell lines, wild-type p53 was present in 3 lines, point mutation was detected in 7 lines, and p53 mRNA was absent in 2 lines. TGF-β₁ was expressed in all 12 lines, but both TGF receptors I and II were expressed in only 6 lines. Addition of TGF-β₁ induced DNA ladder formation only in KATOIII cells, with deleted p53 mRNA, but expressed TGF receptors I and II. CONCLUSIONS. These findings show that TGF-β₁, induces apoptosis in gastric cancer cells through TGF-β receptors I and II and a p53-independent pathway.