Effects Of Octerotide On Proliferation And Apoptosis In Human Gastric Cancer Cell Line BGC-823

Objectives: To study the effects of octreotide on proliferation, apoptosis and cell cycle in human gastric cancer cell line BGC-823, and to explore the effects of octreotide on the expression of apoptotic related genes survivin and PTEN in human gastric cancer cell, and further to explore the possible mechanism of octreotide inducing apoptosis.Methods: (1) The influence of OCT on human gastric cancer cell line BGC-823 was observed with the analysis of cell growth curve. (2) MTT assay and clone formation rate were used to determine the influence of OCT on proliferation of human gastric cancer cell line BGC-823. (3)The influence of OCT on apoptosis was determined by flow cytomery and AO-EB fluorescent staining. (4) Cell cycle was determined by flow cytomery. (5) The expression of apoptotic related genes survivin and PTEN were measured by RT-PCR and western-blot, and undertaked semiguantitative analysis by computer aided video systerm.Results: (1) OCT could inhibit the growth and proliferation of human gastric cancer cell line BGC-823, the inhibitory rate of OCT (10^-5-10^-2g/L ) after 24 hours were 8.21%, 11.3%, 19.4%, 18.3% respectively, after 48 hours were 16.2%, 24.4%, 32.0%, 30.8% respectively, and after 72 hours were 13.3%, 17.9%, 26.5%, 24.1% respectively. The inhibitory rate had a statistical significance between 10^-5-10^-2g/L concentrations compared with negative group (P<0.01), it had a dose-dependent relationship in a range from 10^-5 g/L to 10^-3g/L and a time-dependent relationship within 48 hours. The inhibitory effect of OCT at 10^-3g/L was the most significant, the inhibitory effect of OCT at 10^-2g/L was weaker than 10^-3g/L, the difference between 10^-3g/L and positive group had no statistical significance.(2) Clone formation rate indicated that the quantity of clone formation of OCT(10^-5-10^-3g/L) were significantly less than the negative group (P<0.05).(2) OCT could induce apoptosis of human gastric cancer cell line BGC-823, had a dose-dependent ? relationship in a range from 10^-5 g/L to 10^-3g/L and a time-dependent relationship within 48 hours. The results of apoptosis between AO-EB fluorescent staining and flow cytometry were coincident, the difference had statistical significance compared with negative group (P<0.05).(3) G₁ phase rate gradually increased, S phase rate gradually decreased, cell cycle was arrested at G₁ phase in human gastric cancer cell line BGC-823 treated by OCT(10^-5-10^-3g/L) for 48 hours, the difference had statistical significance compared with negative group (P<0.05).(4) OCT at 10^-5-10^-3g/L reduced the mRNA and protein expression of survivin in human gastric cancer cell line BGC-823 in a dose-dependent relationship, the difference between OCT(10^-5-10^-3g/L) and the negative group had statistical significance(P<0.05); increased the mRNA and protein expression of PTEN, OCT at 10^-5g/L had no statistical significance with negative group(P>0.05), OCT at 10^-4, 10^-3g/Lhad statistical significance with negative group(P<0.05).Conclusions: (1) OCT can inhibit proliferation and induce apoptosis and arrest cell cycle at G₁ phase in human gastric cancer cell line BGC-823, it has a dose-dependent and time-dependent relationship within 10^-5-10^-3g/L.(2) OCT can reduce the mRNA and protein expression of survivin, and increase the mRNA and protein expression of PTEN in human gastric cancer cell line BGC-823.(3) Apoptosis induced by octreotide may be related with arresting cell cycle at G₁ phase, decreasing the expression of survivin and increasing the expression of PTEN in human gastric cancer cell line BGC-823.