Effect of hexachlorobenzene (hcb) and protein x of the hepatitis b virus (hbv) on liver cell growth dysregulation

Abstract

Chronic hepatitis B and exposure to persistent organic pollutants (POPs) can lead to cellular hepatocarcinoma (HCC), the most common liver tumor. HBV DNA encodes transactivator X (HBx). HCB is a COP promoter of hepatic preneoplastic foci. We have shown that HCB deregulates cell growth in rat liver and HepG2 cells, involving TGF-β1, a reversed effect with an Rβ1 inhibitor. Objectives: To analyze in vitro 2 models of HCC generation -associated to HCB or to the expression of HBx- and in vivo the hepatic and angiogenic promoter HCB effect in Balb/c nude mice inoculated with HepG2. M&M: the HCB effect on PCNA (Western blot)/TGF-β1 (RT-PCR) was studied in vitro in: 1.1) Huh-7: HCB at various doses (0.005, 0.05, 0.5 and 5 µM ) and times (15, 30, 60, 90 and 120 min); 1.2) Huh-7 transiently transfected with HBx; 2) HepG2.2.15 (with stable expression of HBV) and 3) EA-hy926 (endothelial). In 1.2, 2 and 3 5 µM HCB, 24h was used. Mice: HCB i.p. (0.3 and 3 mg/ kg), and were inoculated with HepG2. Were evaluated: a) PCNA, b) TGF-β1, c) No . of tumor areas, d) histology (H&E) and e) No . of vessels/mm2 . Results: In Huh-7, TGF-β1 increased (20%, p <0.05; 69% and 78%, p <0.01, with 0.05, 0.5 and 5 µM HCB, respectively) and PCNA (45% and 60%, p <0.01, with 0.5 and 5 µM HCB, respectively). In Huh-7 / HBx, PCNA and TGF-β1 increased 66% and 71% (p <0.01). In Huh-7 / HBx and 5 µM HCB, PCNA increased 120% (p <0.001). In HepG2.2.15 PCNA was overexpressed 76% (p <0.001). In EA-hy926, PCNA (29%, p <0.05) and TGF-β1 (43%, p <0.01) increased. In mice, PCNA (39%; p <0.01), TGF-β1 (48%; p <0.01), preneoplastic areas (320%; p <0.001) and vascularization (35%; p <0.01). Conclusions: HCB promotes preneoplastic cell proliferation and angiogenesis in nude mice inoculated with HepG2, while HCB and HBx induce in vitro cell proliferation associated with the increase of TGF-β1 in the examined lines, a proliferative effect increased to that promoted by the HCB being able to participate in the induction of HCC.