Epithelium and fibroblast-like phenotypes derived from HPV16 E6/E7-immortalized human gingival keratinocytes following chronic ethanol treatment

Epithelial-mesenchymal transition (EMT) may be critical for neoplastic progression and its eventual tumorigenicity of epithelia. In this context, we investigated whether EMT and EMT-associated features occurred after chronic ethanol treatment of human gingival keratinocytes immortalized with the E6/E7 oncogenes of human papillomavirus (HPV) type 16. Following a nine-week treatment of cells with 30 mM ethanol in keratinocyte growth medium, they were cultured in normal DMEM with 10% serum. These cell populations were able to proliferate in this medium gradually exhibiting elongated morphology indicating that these cells underwent EMT. Control cells without ethanol treatment did not survive subcultures in DMEM. Upon long-term subcultures of ethanol-treated cells, two phenotypes were obtained exhibiting epithelium-like and spindle-shape fibroblast-like morphology (respectively, termed as EPI and FIB cells), the latter indicating EMT. In comparison to EPI cells, the phenotypic transition to FIB cells was concomitant with a decrease in the expression of keratins, desmoplakins and a complete loss of K14. Moreover, FIB cell transition strongly correlates with an increase in the expression of vimentin and simple epithelial keratin K18. These alterations in FIB cells were associated with the ability of these cells to exhibit anchorage-independent growth, while EPI cells exhibited anchorage-dependent growth. Concerning the transformation stage, FIB cells represent a progressively more advanced transformed phenotype which may reflect an early step during HPV- and ethanol-dependent multi-step carcinogenesis.     

新疆维吾尔族妇女宫颈癌组织中乳头瘤病毒16型E6基因的克隆和序列分析

为了分析新疆南部地区维吾尔族妇女宫颈癌组织中HPV16型E6基因结构特点，从中国新疆南部地区维吾尔族妇女宫颈癌活检组织标本中提取DNA，以宫颈癌活检组织标本DNA为模板进行PCR扩增，获得HPV16 E6基因，将其克隆到pUCm-T载体上，并对其进行基因全序列分析.PCR检测结果显示宫颈癌组织中HPV16 E6阳性率为82.35%（14/17）；测序结果显示，新疆株HPV16 E6基因全长456 bp，大小与德国标准株一致.E6基因的第247位碱基发生T→G突变，并由此引起所编码的氨基酸亦发生改变.上述结果表明，中国新疆南部地区维吾尔族妇女宫颈癌患者组织中HPV16 E6的基因结构与德国标准株HPV16 E6基因之间存在差异.     

Generation of a human melanocyte cell line by introduction of HPV16 E6 and E7 genes

Summary Availability of a standard human melanocyte cell line with unlimited growth potential and otherwise normal melanocytic properties will greatly facilitate research in melanocyte biology and in vitro studies on the etiology of pigmentary disorders and melanoma. Using a retroviral vector, E6 and E7 open reading frames of human papilloma virus type 16 (HPV 16) have been introduced into cultured normal human melanocytes. Cells selected by increased resistance to geneticin conveyed by the vector and expressing E6E7 mRNA have been cloned to ensure genetic homogeneity. Since their establishment as primary cells, cloned PIG1 cells have undergone more than twice the amount of population doublings of senescent parental cells. Moreover, in passage numbers when parental cells had become senescent, proliferation of clonal cells was retained at levels exceeding those of normal human melanocytes in third passage by 100%. Further characterization has revealed that the cells remain dependent on tetradecanoyl phorbol 13-acetate (TPA) for growth and do not proliferate in soft agar nor form tumors in nude mice. The antigenic profile of the cells was slightly altered as compared to parental cells, but was incomparable to that of M14 melanoma cells. Importantly, PIG1 cells contain more melanin pigment than parental cells.     

HPV16L1VLP纯化、鉴定及血凝抑制实验方法的建立

摘要通过昆虫细胞-杆状病毒表达系统表达HPV16L1 VLP,纯化鉴定后利用其建立血凝抑制实验,检测HPV16L1单克隆抗体的血凝抑制活性。利用重组杆状病毒感染悬浮培养的昆虫细胞表达HPV16L1蛋白,大量获得VLP;优化扩增蛋白的条件并用SDS-PAGE分析鉴定;经氯化铯密度梯度离心法纯化VLP;利用所得VLP建立血凝抑制试验,鉴定制备的HPV16L1单克隆抗体的血凝抑制活性。优化蛋白表达条件结果显示,当重组杆状病毒感染细胞的MOI=10时目的蛋白表达量最大;按此滴度感染悬浮培养的昆虫细胞,收获、纯化VLP并鉴定其特异性;利用所得VLP建立了血凝抑制实验,鉴定HPV16L1单克隆抗体的血凝抑制效价为1∶16。建立的血凝实验,可用于鉴定和检测HPV16L1相关抗体,为HPV诊断试剂的开发提供实验基础。     

腺病毒载体介导密码子优化型HPV 16 L1基因在哺乳动物细胞中的高效表达及病毒样颗粒的装配

为研究重组腺病毒载体作为HPV16预防性疫苗的可行性,构建了含密码子优化型HPV 16 L1基因的重组腺病毒,并对优化基因在哺乳动物细胞中的表达进行研究。首先按照哺乳动物密码子偏好对野生型HPV16 L1基因进行改造并合成优化基因,命名为mod.HPV16L1。将mod.HPV16L1基因克隆到穿梭质粒PDC316上,与骨架质粒共转染293细胞,在细胞内包装重组腺病毒rAd-mod.HPV16L1。用免疫印迹法检测病毒感染的293T细胞中HPV16L1蛋白的表达。通过Optiprep密度梯度超速离心法纯化HPV16 L1病毒样颗粒(VLPs)。用磷钨酸负染,在电子显微镜下观察HPV16 L1蛋白自我装配形成的VLPs。结果显示,重组腺病毒载体可介导mod.HPV16 L1基因在哺乳动物细胞内的高效表达,L1蛋白可自我装配形成VLPs。     

Construction of artificial epithelial tissues prepared from human normal fibroblasts and C9 cervical epithelial cancer cells carrying human papillomavirus type 18 genes

One cervical cancer cell line, C9, carrying human papillomavirus type 18 (HPV18) genes that is one of the major etiologic oncoviruses for cervical cancer was characterized. This cell line was further characterized for its capacity related to the epithelial cell proliferation, stratification and differentiation in reconstituted artificial epithelial tissue. Thein vitro construction of three dimensional artificial cervical epithelial tissue has been engineered using C9 epithelial cancer cells, human foreskin fibroblasts and a matrix made of type I collagen by organotypic culture of epithelial cells. The morphology of paraffin embedded artificial tissue was examined by histochemical staining. The artificial epithelial tissues were well developed having multilayer. However, the tissue morphology was similar to the cervical tissue having displasia induced by HPV infection. The characteristics of the artificial tissues were examined by determining the expression of specific marker proteins. In the C9 derived artificial tissues, the expression of EGF receptor, an epithelial proliferation marker proteins for stratum basale was observed up to the stratum spinosum. Another epithelial proliferation marker for stratum spinosum, cytokeratins 5/6/18, were observed well over the stratum spinosum. For the differentiation markers, the expression of involucrin and filaggrin were observed while the terminal differentiation marker, cytokeratins 10/13 were not detected at all. Therefore the reconstituted artificial epithelial tissues expressed the same types of differentiation marker proteins that are expressed in normal human cervical epithelial tissues but lacked the final differentiation capacity representing characteristics of C9 cell line as a cancer tissue derived cell line. Expression of HPV18 E6 oncoprotein was also observed in this artificial cervical epithelial tissue though the intensity of the staining was weak. Thus this artificial cervical epithelial tissue though the intensity of the staining was weak. Thus this artificial epithelial tissue could be used as a useful model system to examine the relationship between HPV-induced cervical oncogenesis and epithelial cell differentiation.     

应用TDI-FP技术分析宫颈癌组织HPV16 E7基因A647G点突变

模板指导的末端碱基掺入反应结合荧光偏振检测技术(template direct dye-terminator incorporation with fluorescence- polarization,TDI-FP) 是SNP检测新技术. 应用TDI-FP方法分析中国陕西HPV16阳性宫颈组织HPV16 E7基因第647位核苷酸A→G热点突变(即A647G),首先在HPV16阳性的91例宫颈癌及49例正常/宫颈炎妇女宫颈DNA标本中,PCR扩增含647位点在内的HPV16 E7部分基因, 然后将紧邻647位点5′端的寡核苷酸探针与PCR产物内的模板杂交,并延伸一个与647位点碱基互补的荧光标记碱基：TAMRA-ddTTP或R110-ddCTP. 用荧光偏振仪读取荧光偏振 (FP) 值,根据升高的相应FP值判断647位点碱基. 结果表明,宫颈组织HPV16 E7 A647G的总体检出率为35.71% (50/140). 宫颈癌组的A→G突变率为42.86% (39/91),显著高于正常/宫颈炎组22.45% (11/49) 的突变率 (x2 = 5.778, P = 0.016),两组间的OR值为2.59 (95% CI = 1.17~5.71). 提示TDI-FP 可用于HPV有意义点突变的分析;我国陕西地区妇女HPV 16 A647G突变率及其对宫颈癌的警示性与其他地区相比有明显差异,该地区携带此突变病毒株的妇女患宫颈癌的风险可能较高     

The interferon-inducible IFI16 gene inhibits tube morphogenesis and proliferation of primary, but not HPV16 E6/E7-immortalized human endothelial cells

Immunohistochemical analysis has demonstrated that the human IFI16 gene, in addition to the hematopoietic tissues, is highly expressed in endothelial cells and squamous stratified epithelia. In this study, we have developed a reliable HSV-derived replication-defective vector (TO-IFI16) to efficiently transduce IFI16 into primary human umbilical vein endothelial cells (HUVEC), which are usually poorly transfectable. HUVEC infection with TO-IFI16 virus suppressed endothelial migration, invasion and formation of capillary-like structures in vitro. In parallel, sustained IFI16 expression inhibited HUVEC cell cycle progression, accompanied by significant induction of p53, p21, and hypophosphorylated pRb. Further support for the involvement of these pathways in IFI16 activity came from the finding that infection with TO-IFI16 virus does not impair the in vitro angiogenic activity and cell cycle progression of HUVEC immortalized by HPV16 E6/E7 oncogenes, which are known to inactivate both p53 and pRb systems. This use of a reliable viral system for gene delivery into primary human endothelial cells assigns a potent angiostatic activity to an IFN-inducible gene, namely IFI16, and thus throws further light on antiangiogenic therapy employing IFNs.     

The correlations between HPV16 infection and expressions of c-erbB-2 and bcl-2 in breast carcinoma

Breast carcinoma (BC) is a prevalent malignant tumour occurring in women. Many studies have indicated the role of human papilloma virus type 16 (HPV16) in the pathogenesis of BC; however, the correlations of HPV16 infection with the clinicopathologic features of BC and the expressions of c-erbB-2 and bcl-2 have not yet been elucidated. In this study, HPV16 was detected by amplifying the HPV16 E6 gene by the polymerase chain reaction method, and the expressions of c-erbB-2 and bcl-2 in 40 BCs and 20 normal breast tissue samples, obtained from Shaanxi Province, were examined using the streptavidin-peroxidase method with monoclonal antibodies specific to c-erbB-2 and bcl-2. The infection rate of HPV16 E6 and the positive expression rate of c-erbB-2 were significantly higher in the BCs than in the normal tissues (HPV16 E6: 60% vs. 5%; c-erbB-2: 42.5% vs. 5%, P < 0.05). However, the positive expression rate of bcl-2 was significantly lower in the BCs than in the normal tissues (67.5% vs. 95%, P < 0.05). The infection rate of HPV16 did not correlate with any of the pathological features observed (P > 0.05). HPV16 infection correlated with bcl-2 expression (P = 0.015) but not with c-erbB-2 expression (P = 0.747) in the BCs. Interestingly, HPV16 infection correlated with bcl-2 expression in grade I BCs (P = 0.018) but not in grade II–III BCs (P = 0.633). Our data suggest that HPV16 infection is correlated with bcl-2 expression in BCs.     

Induction of senescence-like state and suppression of telomerase activity through inhibition of HPV E6/E7 gene expression in cells immortalized by HPV16 DNA

The E6 and E7 oncoproteins of human papillomavirus (HPV) play a major role in the development of cervical carcinoma. In this study, a recombinant adenovirus that expresses the bovine papillomavirus (BPV) E2, which has been shown to inhibit HPV early gene expression, was delivered to two HPV-immortalized cell lines as well as CaSki, a cervical carcinoma cell line. We tested whether the carcinoma and the immortal cells were equally affected by the expression of BPV E2. In all cell lines, BPV E2-mediated inhibition of HPV E6/E7 expression caused a dramatic suppression of cell growth, being preceded by the activation of the p53-Rb growth-inhibitory pathway, and a decrease in hTERT mRNA expression and telomerase activity. This suggests that the HPV E6 and E7 proteins are required not only for induction of the proliferative phenotype and telomerase activity, but also for their maintenance. In both the carcinoma and the immortal lines, the number of cells with enlarged cytoplasm and senescence-associated beta-galactosidase activity, which are markers for cellular senescence, was significantly increased. These results suggest that a senescence program exists in cells immortalized by HPV DNA as well as in cervical carcinoma cells.     

人乳头瘤病毒16型E6和E7基因及其突变体转化活性的研究

为筛选出可用于研制HPV治疗性疫苗的HPV16型E6和E7基因突变体,故将HPV16型原型株(德国株)E6和E7基因及其各种突变体分别转染Balb/c3T3细胞,观察转染后的细胞在软琼脂培养中的集落形成能力和在裸鼠体内的成瘤能力.结果表明,单独转染和共转染HPV16野生型E6和E7基因的Balb/c3T3细胞系,在软琼脂中呈集落样生长,并在裸鼠体内成瘤;而转染E6基因突变体mE6(50G)、E7基因的两种突变体mE7-1(24G26G)和mE7-3(24G26G67R)以及共转染mE6和mE7-1的Balb/c3T3细胞,在软琼脂培养中极少形成集落,也不能在裸鼠体内成瘤.提示经结构改造后的HPV16 E6和E7基因已失去了对Balb/c3T3细胞的转化活性,而保留了免疫原性,可用于HPV16相关肿瘤治疗性疫苗的构建.     

人乳头瘤病毒16型L1和L2基因表达产物的鉴定

目的:构建人乳头瘤病毒(human papillomavirus,HPV)16型晚期基因L1及L2的原核表达质粒,并验证目的蛋白的表达.方法:用限制性酶切及连接的方法构建原核表达质粒pET3a-16 L1和pET3a-16 L2,通过SDS-PAGE及Westen blot检测目的融合蛋白的表达.结果:在大肠菌中诱导表达的L1蛋白分子量约为57 KD,L2蛋白分子量约为90 KD.结论:该实验结果为HPV16型预防性基因工程亚单位疫苗的研制和诊断试剂的研究开发奠定了基础.     

Clearance of senescent cells reverts the cigarette smoke-induced lung senescence and airspace enlargement in p16-3MR mice

Cigarette smoke (CS) leads to increased oxidative stress, inflammation, and exaggerated senescence, which are involved in the pathogenesis of chronic obstructive pulmonary disease (COPD). While the role of cellular senescence in COPD is known, it is not clear if the removal of senescent cells could alleviate the disease symptoms. To test this, we used the novel mouse model-p16-3MR, and studied the effect of ganciclovir (GCV)-mediated removal of senescent cells after chronic CS (3 months) and environmental tobacco smoke (ETS) (6 months) exposure to CS. Our results showed the reversal of CS-induced cellular senescence on the clearance of p16⁺ senesced cells by GCV treatment. Interestingly, the clearance of p16⁺ senescent cells via GCV led to a decrease in the neutrophil counts in the BALF of GCV-treated CS-exposed p16-3MR mice, as well as reversal of CS-mediated airspace enlargement in p16-3MR mice. Mice exposed to low dose ETS caused insignificant changes in the SA-β-Gal⁺ senescent cells and airspace enlargement. Overall, our data provide evidence for the role of lung cellular senescence on smoke exposure and clearance of senescent cells in p16-3MR mice in the reversal of COPD/emphysema pathology with a possibility of senolytics as therapeutic interventions in COPD.     

PTEN、HPV16/18-E6蛋白和雌激素受体在宫颈腺癌中的表达及其临床意义

目的：探讨宫颈腺癌组织中抑癌蛋白PTEN、人乳头瘤病毒（HPV）16/18-E6蛋白和雌激素受体（ER）的表达及其临床意义。方法：采用免疫组织化学S-P法对65例宫颈腺癌组织进行PTEN、HPV16/18-E6蛋白和ER检测,对30例慢性宫颈炎组织中HPV16/18-E6蛋白和ER的表达进行检测。结果：宫颈腺癌组织细胞核中PTEN的表达显著低于癌旁宫颈腺上皮组织（P〈0.01）,96%的宫颈腺癌细胞核呈低表达,而仅35%的癌旁宫颈腺上皮呈低表达（P〈0.01）;HPV16/18-E6蛋白和ER在宫颈腺癌中的阳性表达率分别为32.1%与49.4%,均显著高于慢性宫颈炎组织（P〈0.01）;HPV16/18-E6蛋白和ER的表达与宫颈腺癌的病理学分级、临床分期无关,在宫颈腺癌中的表达呈正相关。结论：PTEN在宫颈腺癌的发生中起一定的作用,其抑癌作用环节可能在细胞核水平;部分宫颈腺癌的发病可能与HPV16/18-E6蛋白过度表达有关;部分宫颈腺癌可能属于激素依赖性,雌激素可能有协同人乳头瘤病毒致癌的作用。     

Immortalization of normal human mammary epithelial cells in two steps by direct targeting of senescence barriers does not require gross genomic alterations

Telomerase reactivation and immortalization are critical for human carcinoma progression. However, little is known about the mechanisms controlling this crucial step, due in part to the paucity of experimentally tractable model systems that can examine human epithelial cell immortalization as it might occur in vivo. We achieved efficient non-clonal immortalization of normal human mammary epithelial cells (HMEC) by directly targeting the 2 main senescence barriers encountered by cultured HMEC. The stress-associated stasis barrier was bypassed using shRNA to p16^INK4; replicative senescence due to critically shortened telomeres was bypassed in post-stasis HMEC by c-MYC transduction. Thus, 2 pathologically relevant oncogenic agents are sufficient to immortally transform normal HMEC. The resultant non-clonal immortalized lines exhibited normal karyotypes. Most human carcinomas contain genomically unstable cells, with widespread instability first observed in vivo in pre-malignant stages; in vitro, instability is seen as finite cells with critically shortened telomeres approach replicative senescence. Our results support our hypotheses that: (1) telomere-dysfunction induced genomic instability in pre-malignant finite cells may generate the errors required for telomerase reactivation and immortalization, as well as many additional “passenger” errors carried forward into resulting carcinomas; (2) genomic instability during cancer progression is needed to generate errors that overcome tumor suppressive barriers, but not required per se; bypassing the senescence barriers by direct targeting eliminated a need for genomic errors to generate immortalization. Achieving efficient HMEC immortalization, in the absence of “passenger” genomic errors, should facilitate examination of telomerase regulation during human carcinoma progression, and exploration of agents that could prevent immortalization.     

Expression of p16INK4A variants in senescent human fibroblasts independent of protein phosphorylation

Upregulation of the p16 tumor suppressor is a hallmark of senescence in human fibroblasts. In this study, we investigated potential protein modification of p16 in senescent human fibroblasts using 2D SDS-PAGE analysis. Three distinct p16 variants with isoelectric points of 5.2, 5.4, and 5.6, were consistently detected in normal human IMR90 fibroblasts that had undergone senescence due to forced expression of oncogenic H-ras or culture passage. Moreover, in contrast to short-term serum starvation, which induces quiescence, IMR90 fibroblasts cultured in low serum for a prolonged period exhibited senescent phenotypes and expression of the three p16 variants. All three p16 variants are unlikely phosphoproteins since they failed to react with antibodies against phospho-serine, and were resistant to the treatment with phosphatases. Functionally, co-immunoprecipitation assays using antibodies against cdk4 and/or cdk6 revealed that only the two most acidic p16 variants associated with cdk4/6. Moreover, senescence induced by the forced expression of p16 in early passage IMR90 fibroblasts or osteosarcoma U2OS cells was accompanied by expression of the two most acidic p16 variants, which also associated with cdk4/6. In summary, we report that prolonged serum starvation-induced senescence may provide an additional model for studying biochemical changes in senescence, including p16 regulation. Furthermore, induction of endogenous p16 in senescent human fibroblasts correlates with the expression of three distinct p16 variants independent of protein phosphorylation. Lastly, expression of the two cdk-bound variants is sufficient to induce senescence in human cells.     

Pin1，CyclinD1在宫颈癌中的表达及与HPV16／18感染的关系

研究肽基脯氨酰顺反异构酶Pin1,CyclinD1在宫颈液基细胞上皮内病变和宫颈癌中的表达与HPV16/18感染的关系,探讨其对宫颈上皮内病变和宫颈癌诊断的意义。经液基细胞学筛查,采用原位杂交方法对80例宫颈上皮内病变和宫颈癌,13例正常组织进行HPV检测分型,同时对HPV16/18阳性的标本进行Pin1,CyclinD1免疫组化。在正常宫颈组织、CINⅠ,CINⅡ-Ⅲ,浸润癌组织中Pin1表达率分别为7.7%(1/13)、57.1%(12/21)、68.4%(13/19)、85%(34/40)(P<0.05);CyclinD1表达率分别为0%、9.52%(2/21)、20.5% (4/19)、55%(22/40)。HPV16/18的表达率也随着宫颈病变的升级而升高,分别为15.4%(2/13)、42.9%(9/ 21)、57.9%(11/19)、82.5%(33/40)。Pin1和HPV16/18在宫颈病变中的表达高度相关(r_0=1.0,P<0.05);而CyclinD1的表达与HPV16/18相关性较小(r_0=0.4,P<0.05)。认识Pin1,cyclinD1和HPV16/18三者之间的关系及对宫颈上皮内病变和宫颈癌的筛查诊断具有重要意义。