The research for sodium valproate depress the expression of proliferating cell nuclear antigen and heparanase of hepatocellular carcinoma in nud mice via reversing low-level histone acetylation

Abstract

Objective To explore the inhibitory effect of sodium valproate on human hepatoma cell line SMMC-772l xenograft in nud mice and the possible mechanisms. Methods The nude mice tumor model was established by subcutaneous injection of hepatic cancer cells in the right upper limb of the mice. When the tumor grew to (100-150) mm3, the mice were divided randomly into two groups and injected with VPA or DMSO respectively. The volume and weight of tumor were measured. Real-time PCR assay was used to detect the expression of proliferating cell nuclear antigen (PCNA) and heparanase (HPA) mRNA in tumor tissues of different groups. Western blotting assay and immunohistochemistry were used to detect the expression of PCNA and HPA protein in tumor tissues of different groups. Results The volume and weight of treatment group were significantly lower than the control group at the end of the experiment [(0.261±0.070) cm3 vs. (0.396±0.010) cm3, t=-42.321, P<0.05, (0.51±0.07) g vs. (0.83±0.14) g, t=-26.116, P<0.05]; RT-PCR results showed that compared with control group, the expression of PCNA and HPA mRNA in VPA-treated group was remarkably suppressed [(0.491±0.06) vs. (0.899±0.038), t=-112.316, P<0.05, (0.438±0.016) vs. (0.829±0.036), t=-127.768, P<0.05]; Western blotting assay and immunohistochemistry showed that the level of PCNA and HPA protein in VPA-treated group were lower remarkably than that in control group [(0.816±0.063) vs. (1.592±0.071), t=-17.561, P<0.05; (0.879±0.083) vs. (1.792±0.170), t=-17.140, P<0.05]. Conclusion The in vivo study showed that VPA may down regulate the expression of PCNA and HPA by reversing the low acetylation level of histone proteins, so as to inhibit the proliferation and decrease the ability of invasion and metastasis of hepatocellular carcinoma cells. Key words: Sodium valproate; Histone acetylation; Hepatocellular carcinoma; Proliferating cell nuclear antigen; Heparanase