Mukherjee Rathindra M, Shravanti Gelli V, Jakkampudi Aparna, Kota Ramya, Jangala Asha L, Reddy Panyala B, Rao Padaki N, Gupta Rajesh, Reddy Duvvuru N
Asian Health Care Foundation, Institute of Basic and Translational Research, 6-3-661, Somajiguda, Hyderabad 500082, India.
Asian Institute of Gastroenterology, Somajiguda, Hyderabad, India.
J Clin Exp Hepatol. 2013 Jun;3(2):89-95. doi: 10.1016/j.jceh.2013.04.003. Epub 2013 May 22.
High mobility group box1 (HMGB1) and poly(ADP-ribose) polymerase1 (PARP1) proteins repair cellular DNA damage. Reduced expression of the corresponding genes can lead to an impaired DNA damage repair mechanism. Intracellular replication of hepatitis B virus (HBV) in such conditions can favor the integration of viral DNA into host genome leading to the development of hepatocellular carcinoma (HCC).
This study was performed to assess the expression of HMGB1 and PARP1 mRNAs in conjunction with the estimation of HBV replication intermediate pregenomic RNA (PgRNA) in various phases of HBV infection.
Eighty eight patients and 26 voluntary blood donors as controls were included in the study. Patients were grouped in to acute (AHB; n = 15), inactive carriers (IC; n = 36), cirrhosis (Cirr; n = 25) and hepatocellular carcinoma (HCC; n = 12). Serum HBV DNA was quantified by real time polymerase chain reaction (PCR) assay. Expression of HMGB1, PARP1 and PgRNA were evaluated using peripheral blood mononuclear cells (PBMCs) derived RNA by reverse transcription PCR (RT-PCR) and densitometry.
Significant reduction of HMGB1 and PARP1 gene expressions (P < 0.05) were observed in patients than controls with more explicit decline of PARP1 (P = 0.0002). Both genes were significantly downregulated (P < 0.001) in ICs than controls. In ICs, HMGB1 was significantly lowered than cirrhosis (P = 0.002) and HCC (P = 0.0006) while PARP1 declined significantly (P = 0.04) than HCC. Level of PgRNA was comparable in all the disease categories.
In conclusion, our findings indicate impaired DNA damage repair mechanisms in HBV infected cells of ICs. This, along with low viral load but higher level of PgRNA in this group is suggestive of the diversion of HBV replication pathway that might facilitate viral DNA integration in to host genome. Intrusion of HBV PgRNA reverse transcription in early stage of infection might appear advantageous to thwart the development of HCC.
高迁移率族蛋白盒1（HMGB1）和聚（ADP - 核糖）聚合酶1（PARP1）蛋白可修复细胞DNA损伤。相应基因表达降低会导致DNA损伤修复机制受损。在这种情况下，乙型肝炎病毒（HBV）在细胞内复制有利于病毒DNA整合到宿主基因组中，从而导致肝细胞癌（HCC）的发生。
本研究旨在评估HMGB1和PARP1 mRNA的表达，并同时估计HBV感染各阶段的复制中间体前基因组RNA（PgRNA）。
本研究纳入了88例患者和26名作为对照的自愿献血者。患者被分为急性乙型肝炎（AHB；n = 15）、非活动性携带者（IC；n = 36）、肝硬化（Cirr；n = 25）和肝细胞癌（HCC；n = 12）。通过实时聚合酶链反应（PCR）测定血清HBV DNA含量。使用外周血单个核细胞（PBMCs）提取的RNA，通过逆转录PCR（RT - PCR）和光密度测定法评估HMGB1、PARP1和PgRNA的表达。
与对照组相比，患者中HMGB1和PARP1基因表达显著降低（P < 0.05），PARP1下降更为明显（P = 0.0002）。与对照组相比，IC组中这两个基因均显著下调（P < 0.001）。在IC组中，HMGB1显著低于肝硬化组（P = 0.002）和HCC组（P = 0.0006），而PARP1显著低于HCC组（P = 0.04）。所有疾病类别中PgRNA水平相当。
总之，我们的研究结果表明IC组HBV感染细胞中的DNA损伤修复机制受损。此外，该组病毒载量低但PgRNA水平较高，提示HBV复制途径发生改变，这可能促进病毒DNA整合到宿主基因组中。在感染早期HBV PgRNA逆转录的介入可能对阻止HCC的发生具有优势。
