Effect of cis-9, trans-11-conjugated linoleic acid on cell cycle of gastric adenocarcinoma cell line (SGC-7901)

Abstract

Aim: To determine the effect of cis -9, trans -11-conjugated linoleic acid (c9, t11-CLA) on the cell cycle of gastric cancer cells (SGC-7901) and its possible mechanism in inhibition cancer growth.

Methods: Using cell culture and immunocytochemical techniques, we examined the cell growth, DNA synthesis, expression of PCNA, cyclin A, B(1), D(1), p16(ink4a) and p21(cip/waf1) of SGC-7901 cells which were treated with various c9, t11-CLA concentrations (25, 50, 100 and 200 micromol.L(-1))of c 9, t 11-CLA for 24 and 48h, with a negative control (0.1% ethane).

Results: The cell growth and DNA synthesis of SGC-7901 cells were inhibited by c9, t11-CLA.SGC-7901 cells. Eight day after treatment with various concentrations of c9, t11-CLA mentioned above, the inhibition rates were 5.92%, 20.15%, 75.61% and 82.44%, respectively and inhibitory effect of c9, t11-CLA on DNA synthesis (except for 25 micromol.L, 24h) showed significantly less (3)H-TdR incorporation than that in the negative controls (P<0.05 and P<0.01). Immunocytochemical staining demonstrated that SGC-7901 cells preincubated in media supplemented with different c9, t11-CLA concentrations at various times significantly decreased the expressions of PCNA (the expression rates were 7.2-3.0%, 24h and 9.1-0.9% at 48h, respectively), Cyclin A (11.0-2.3%, 24h and 8.5-0.5%,48h), B(1) (4.8-1.8% at 24h and 5.5-0.6% at 48h)and D(1) (3.6-1.4% at 24h and 3.7%-0 at 48h) as compared with those in the negative controls(the expressions of PCNA, Cyclin A, B(1) and D(1) were 6.5% at 24h and 9.0% at 48h, 4.2% at 24h and 5.1% at 48h, 9.5% at 24h and 6.0% at 48h,respectively)(P<0.01), whereas the expressions of P16(ink4a) and P21(cip/waf1), cyclin-dependent kinases inhibitors(CDKI), were increased.

Conclusion: The cell growth and proliferation of SGC-7901 cell is inhibited by c9, t11-CLA via blocking the cell cycle, with reduced expressions of cyclin A,B(1) and D(1) and enhanced expressions of CDKI(P16(ink4a) and p21(cip/waf1)).

Figure 1

Growth curve of SGC-7901 cells cultured in various concentration of c9,t11-CLA

Figure 2

Expression of PCNA on SGC-7901 cells treated with c9,t11-CLA

Figure 3

A: The expression of PCNA on SGC-7901 cells of the negative controls (immunocytochemistry staining SP method, original magnification × 400); B: The expression of cyclin A on SGC-7901 cells of the negative controls (immunocytochemistry staining SP method, original magnification × 400); C: The expression of cyclin B₁ on SGC-7901 cells of the negative controls (immunocytochemistry staining SP method, original magnification × 400); D: The expression of cyclin D₁ on SGC-7901 cells of the negative controls (immunocytochemistry staining SP method, original magnification × 400); E: The expression of P16^inf4aon SGC-7901 cells of c9,t11-CLA group (100 μmol•L⁻¹) (immunocytochemistry staining SP method, original magnification × 400); F: The expression of P21^cip/waf1 on SGC-7901 cells of c9,t11-CLA group (100 μmol•L⁻¹) (immunocytochemistry staining SP method, original magnification × 400)

Figure 4

The relationship between CDKI (P16 and P21) and cyclins in G₁/S transition