Clinicopathological characteristics of PIK3CA and HBx mutations in Korean patients with hepatocellular carcinomas

Hepatocellular carcinoma (HCC) is the fourth most common form of cancer in the Korean population, caused primarily by infection with either the Hepatitis B or C virus. Progression of this disease is frequently associated with mutations in either phosphoinositide‐3‐kinase, catalytic, alpha (PIK3CA) or hepatitis B virus X (HBx) gene. Previous studies have examined the frequency of PIK3CA mutations in HCC, although the clinical significance of these mutations has not been studied in a Korean population. In addition, HBx appears to play a key role in modulating a wide range of cellular functions, leading to HCC. In this study, we examined microdissected tumor samples from 50 HCC patients who underwent hepatectomy at Keimyung University Dongsan Medical Center. These patients were screened for mutations in PIK3CA and HBx to identify the clinical outcomes associated with these mutations. Exons 9 and 20 of PIK3CA and the entirety of HBx were screened for mutations by polymerase chain reaction and direct DNA sequencing. PIK3CA mutations were detected in 7 of 50 patients (14%). Among the 42 patients who were seropositive for hepatitis B, 17 (40.5%) had HBx mutations and 4 (9.52%) had mutations in PIK3CA. PIK3CA mutations were strongly correlated with tumor size. Patients harboring HBx mutations exhibited a longer time to recurrence; this difference was statistically significant not only in comparison with the PIK3CA mutation but also compared with those without any mutations. This result suggests a role for PIK3CA and HBx mutations as prognostic markers in HCC.     

RNA干扰HBx基因对肝癌细胞化疗效果的影响

目的：探讨RNA干扰技术和传统的化疗方法联合应用对肝癌细胞生长抑制作用的影响,并选择高效的治疗组合,研究其凋亡机制。方法：鉴定3组肝癌细胞——MHCC97-H(原肝癌细胞株),HK3细胞（转染空质粒的MHCC97-H细胞）和21543细胞（转染含HBx-shRNA质粒的MHCC97-H细胞）;RT-PCR检测RNA干扰对HBx mRNA沉寂作用,CCK8和TUNEL分别检测RNA干扰HBx后化疗药物对MHCC97-H肿瘤细胞生长的抑制及诱导细胞凋亡情况。结果：RT-PCR结果显示,与MHCC97-H细胞组比较,21543细胞的HBx mRNA水平下降约91%,HK3细胞HBx mRNA水平下降不明显;RNA靶向干扰HBx基因后的肝癌细胞（21543细胞）较原肝癌细胞（MHCC97-H细胞）和HK3细胞增殖明显减慢,而后两种细胞差别无统计学意义;3种不同细胞加用3种不同浓度的氟尿嘧啶(0~120 mg/L)、顺铂(0~32 mg/L)后细胞生长明显减慢并呈浓度依赖性,以RNA靶向干扰HBx基因后的21543细胞生长抑制最明显;相同浓度的氟尿嘧啶对3组不同肝癌细胞均可引起细胞凋亡,以21543细胞凋亡最明显。结论：RNA干扰HBx可明显抑制肝癌细胞的增殖,并增加肝癌细胞对化疗药物的敏感性;RNA干扰HBx基因和化疗药物联合应用使肝癌细胞凋亡更明显,细胞增殖速度明显减慢。     

HBx基因缺失突变体HBx-d382对L02细胞增殖及非锚定依赖生长能力的影响

目的:建立稳定表达HBx基因缺失突变体(HBx-d382)的L02肝细胞株,并探讨其对L02细胞增殖的影响.方法:含HBx-d382重组质粒(pCDNA3.0/HBx-d382)经过PCR扩增、双酶切及测序鉴定后,通过脂质体转染和G418筛选获得稳定表达HBx-d382的L02肝细胞株.PCR鉴定基因组中HBx-d382基因整合.RT-PCR和Western blot鉴定其表达,进一步通过MTT法,软琼脂克隆形成实验检测HBx-d382对L02细胞增殖及非锚定依赖生长能力的影响.用流式细胞仪检测其对细胞周期的影响.结果:经PCR扩增、双酶切及测序鉴定HBx-d382重组质粒构建正确.稳定转染该质粒的L02细胞基因组存在HBx-d382整合.RT-PCI汲Western blot表明在RNA水平和蛋白水平存在HBx-d382表达,稳定表达HBx-d382的L02细胞其增殖能力和非锚定生长能力增强,S+G2期细胞比例升高.结论:成功构建了HBx缺失突变体的真核表达模型,证实HBx缺失突变体能影响细胞增殖,这种效应可能与其影响细胞周期调控相关.     

肝细胞癌中HBx蛋白与生存素蛋白表达的关系及其意义

目的：探讨乙型肝炎病毒X蛋白（HBx）与生存素在肝细胞癌（HCC）表达发生中的作用。方法：采用免疫组织化学测定58例患者的HCC组织中HBx蛋白和生存素蛋白表达,用含有辣根过氧化物酶底物的试剂合（DAB）显色,已知的肝癌组织HBx及生存素阳性切片为阳性对照,磷酸盐缓冲液（PBS）作为空白对照。结果：HCC组织HBx和生存素的表达率分别为46.6%（27/58）和69.0%（40/58）,HBx蛋白阳性的HCC组织中生存素蛋白阳性表的阳性率为70.4%（19/27）,HBx蛋白的阴性的HCC组织中生存素蛋白阳性表的阳性率为27.5%（11/40）,差异有统计学意义（P〈0.05）;HBx蛋白与生存素蛋白表达与HCC分化程度、转移及甲胎蛋白（AFP）相关。结论：在HCC的发生过程中HBx蛋白可上调生存素蛋白的表达,促进肝细胞癌的发生发展。     

乙型肝炎病毒X基因对肝癌细胞Bel-7404细胞周期的影响

目的:构建转基因细胞株Bel-7404/HBx,研究HBx对肝癌细胞周期及凋亡的影响,为探索HBx与原发性肝细胞癌(HCC)之间的关系提供更为完善的理论依据。方法:运用脂质体转染及G418筛选获取Bel-7404/HBx阳性克隆,并分别用聚合酶链反应(RT-PCR)和Western-blot鉴定HBxmRNA与蛋白的表达,进一步用四唑兰比色实验(MTT)检测Bel-7404/HBx的增殖,流式细胞仪(FCM)检测Bel-7404/HBx的细胞周期及凋亡。结果:成功构建Bel-7404/HBx,MTT检测结果表明Bel-7404/HBx生长速度加快,流式细胞仪检测结果显示,与对照组细胞相比,Bel-7404/HBx凋亡率明显降低(P<0.05),G1期细胞比例降低(P<0.05),S期及G2期细胞所占比例增高(P<0.05)。结论:HBx能加速细胞周期进程,从而促进肝癌细胞的生长并抑制细胞凋亡,可能对肝癌细胞恶性程度具有重要的影响。     

HBx和mIL-12双基因重组腺病毒的构建

目的 构建携带双基因HBx和mIL-12的重组腺病毒Ad-HBx-mIL-12.方法 采用酶切、连接的方法分别将基因HBx和mIL-12连接到穿梭质粒载体pAdenoVator-CMV5.将构建正确的穿梭质粒pAdV-HBx-mIL-12经EcoR Ⅰ酶切线性化后,转化于含腺病毒骨架质粒pAdenoVatorΔE1/E3的BJ5183感受态细菌,实现细菌内同源重组.将鉴定正确的重组腺病毒质粒pAd-HBx-mIL-12经Pac Ⅰ酶切线性化后,以脂质体法转染至293细胞,包装并扩增获得携带双基因HBx和mIL-12的重组腺病毒Ad-HBx-mIL-12.结果 经鉴定携带HBx和mIL-12双基因的重组腺病毒构建成功,并可在293细胞中有效表达.结论 成功构建了携带双基因HBx和mIL-12的重组腺病毒Ad-HBx-mIL-12,为探讨其联合抗肿瘤机制及后续基因治疗奠定了基础.     

HBx、MHBs~（t155）真核表达载体构建及在HepG2细胞中的表达

目的建立稳定、高效的HBx、羧基末端截短的中分子表面蛋白（MHBst）体外表达细胞株,以进一步研究HBx、MHBst蛋白在肝癌发生中的作用及其机理。方法设计特异性引物,采用PCR方法从adr亚型HBV质粒pHBV DNA中扩增HBx、羧基末端截短至155位氨基酸的中分子表面蛋白（MHBst155）编码基因,并定向插入绿色荧光蛋白（GFP）表达载体pEGFP-C1的BglⅡ、KpnⅠ和BglⅡ、BamHⅠ酶切位点,转化宿主菌DH5α,提取质粒,分别用上述内切酶酶切及DNA测序鉴定重组质粒。采用脂质体介导将空载体、重组质粒分别转染到人肝肿瘤细胞株HepG2中,G418筛选抗性细胞克隆,荧光显微镜下观察GFP表达,挑取表达GFP的抗性克隆扩大培养、传代。采用RT-PCR、蛋白印迹检测抗性细胞中HBx、MHBst155的mRNA及蛋白水平。结果经酶切及测序鉴定成功构建了pGFP-HBx、pGFP-MHBst155重组表达载体,将空载体及重组质粒转染HepG2,经G418筛选约20 d获得抗性细胞克隆。将带有绿色荧光的抗性克隆扩大培养并经传代40次,细胞仍表达强的绿色荧光。RT-PCR及蛋白印迹检测表明转染重组体的HepG2/GFP-HBx、HepG2/GFP-MHBst155细胞有相应的条带,而空载体、空白对照组未出现条带。结论成功构建了HBx、MHBst155真核重组表达载体pGFP-HBx、pGFP-MHBst155,获得了稳定表达融合蛋白GFP-HBx、GFP-MHBst155的HepG2细胞系,为进一步研究HBx及MHBst蛋白在肝癌发生中的作用及分子机制构建了良好的平台。     

小鼠肝脏导入HBx基因诱导MIG的表达

目的将HBx基因转入小鼠肝组织并探讨体内HBx对MIG表达的影响。方法携带HBx的质粒和空载体质粒分别与去唾液酸蛋白体内转染系统(in vivo-jetPEI-Gal system)孵育,形成去唾液酸蛋白受体-聚乙烯亚胺-DNA复合物。将复合物经尾静脉高压注射入小鼠体内,2d后处死小鼠摘取肝脏,采用RT-PCR、免疫组织化学、Western blot法分别检测HBx和MIG的表达。结果空白组和阴性对照组小鼠肝组织无HBx表达,实验组RT-PCR测mRNA表达结果为(1.416±0.025),免疫组化法测定HBx蛋白表达阳性面积率为(35.741±2.245)%,Western blot法检测蛋白表达为(1.357±0.031)(P<0.01)。MIG mRNA在空白组、阴性对照组、实验组中的表达分别为(0.106±0.036)、(0.112±0.027)、(0.238±0.051);免疫组化显示MIG蛋白阳性表达面积分别是(10.157±0.841)%、(11.234±0.627)%、(24.568±3.246)%;Western blot检测结果显示MIG蛋白表达分别为(0.149±0.053)、(0.156±0.042)、(0.349±0.087)。MIG mRNA和蛋白在实验组表达均明显高于空白组和阴性对照组(均P<0.05)。结论去唾液酸蛋白与携带HBx质粒形成去唾液酸-聚乙烯亚胺-DNA复合物,通过尾静脉高压注射法可高效地将HBx基因转入小鼠肝脏组织。而且,转入的HBx基因能有效诱导MIG mRNA和蛋白表达。     

Depletion of β-catenin from mature hepatocytes of mice promotes expansion of hepatic progenitor cells and tumor development

Depletion of β-catenin impairs regeneration of the rapid turn-over gut epithelial cells, but appears dispensable for that of the slow turn-over mature hepatocytes in mice until 1 y of age. As the life span of mature murine hepatocytes is about 400 d, we studied conditional β-catenin knockout mice (Alb-Cre;Ctnnb1(flx/flx)) until 20 mo of age to determine the function of β-catenin in the postnatal liver. β-catenin was absent from the hepatocytes of β-catenin knockout mice 4 wk after delivery. From 9 mo of age, hepatocytes were gradually replaced by newly formed β-catenin-positive hepatocytes, which constituted about 90% of hepatocytes at 18-20 mo of age. This process was accompanied by active proliferation of bile duct/ductule cells. β-catenin-positive hepatocytes exhibited elevated proliferation activity and expression of progenitor cell markers, but lower albumin and Cre. This might explain their intact β-catenin protein, and suggest their origins from hepatic progenitor cells. Liver tumors arose spontaneously from β-catenin-positive cells, and tumorigenesis was accelerated by hepatitis B X protein. These results indicate β-catenin critical for the regeneration of mature hepatocytes. Failure to regenerate mature hepatocytes results in proliferation of hepatic progenitor cells that are able to maintain liver function but are predisposed to form liver tumors.     

Involvement of the NF-κB pathway in multidrug resistance induced by HBx in a hepatoma cell line

It is widely believed that hepatocellular cancer (HCC), especially HBV associated HCC, is highly resistant to chemotherapy. To investigate the molecular influence of HBx protein on multidrug resistance (MDR) in HCC and the potential role of the NF-κB pathway in this process. We established HBx-expressing cells by liposome-mediated transfection of the HBx into the HepG2 cell line. We found that HBx expression in HCC cells induces drug resistance against multiple drugs, a significantly lower apoptosis ratio in HepG2-HBx and HepG2.2.15 cells, compared with HepG2 and HepG2-3.1 cells (P < 0.05) after treating with 5-FU or adriamycin. And compared with the control group, the HBx-transfected cells showed a higher expression of MDR-associated and anti-apoptotic genes. Furthermore, we found that the NF-κB activity was remarkably high in the HBx-expressing cells as measured by p65 nuclear localization. In addition, the upregulated anti-apoptotic genes, Gadd45b and Survivin, in HBx-expressing HCC cells were downregulated by IMD-0354 treatment, which is the NF-κB pathway inhibitor. Taken together, these results suggest that HBx protein might be one of the causes for the occurrence of MDR in HCC, and the NF-κB pathway might be involved in this change.