Effect on cancer cells of plasmids that express antisense RNA of human papillomavirus type 18.

Some human squamous cell carcinomas contain DNA of human papillomaviruses (HPV) and express RNA from the E6 and E7 genes. We have examined the effect of plasmids that express antisense RNA of these genes on the growth of the human cancer cell lines HeLa, C4-1, and 1483, which contain HPV type 18 DNA. As controls, the human cancer cell line 183 and the Vero line of monkey kidney cells were used, which do not contain HPV. Plasmids were introduced into the cells by electroporation; cells that contained HPV type 18 accepted the antisense-expressing plasmids at a lower frequency than the cells that lacked HPV. Cell lines were developed from HeLa cells that contained sense- or antisense-expressing plasmids, and lines that contained antisense-expressing plasmids showed slower growth, reduced ability to form colonies in soft agar, and increased serum requirements. The use of antisense HPV RNA might be a suitable approach to gene therapy of HPV-expressing human cancers.     

Tumorigenic Transformation of Primary Rat Embryonal Fibroblasts by Human Papillomavirus Type 8 E7 Gene in Collaboration with the Activated H-ras Gene

Particular types of human papillomavirus (HPV) are associated with skin cancer of epidermo-dysplasia verruciformis (EV) patients. Here, we show, for the first time, that the E7 gene of EV-associated HPV8 possesses a potential oncogenic transforming ability. The HPV8 E7 open reading frame (ORF) and the HPV16 E7 ORF were cloned under the SV40 promoter/enhancer to construct recombinant plasmids pcD2-8E7 and pcD2-16E7, respectively. Transfection of primary rat embryonal flbroblasts having an activated H- ras gene revealed that pcD2-8E7 as well as pcD2-16E7 induced transformation of cells In G418-resistant colonies at an efficiency of 12.3% and 42.9%, respectively. The resulting transformed cell lines induced by pcD2-8E7 and activated H- ras were tumorigenic when injected into syngeneic immunocompetent rats. The potential tumorigenicity of HPV8 E7 seemed to be higher than that of HPV16 E7.     

Down-regulation of the insulin-like growth factor I receptor by antisense RNA can reverse the transformed phenotype of human cervical cancer cell lines

The insulin-like growth factor I receptor (IGF-IR) plays an essential role in the establishment and maintenance of transformed phenotype, and interference with the IGF-IR pathway by antisense or dominant-negative mutants causes reversal of the transformed phenotype in many rodent and human tumor cell lines. We stably transfected an IGF-IR antisense mRNA expression plasmid into human papillomavirus (HPV)-negative C33a cell line, HPV-16-positive SiHa cell line, and HPV-18-positive HeLa S3 cell line to determine whether the IGF-IR could be a target for cervical cancer cells, especially in the presence of HPV. Approximately 30-80% down-regulation of IGF-IR expression was observed by Western blot in antisense transfected clones. There was a little inhibition in monolayer growth in all cell lines. In C33a cells, wild-type and sense clones formed 92-146 colonies in soft agar after 3 weeks; antisense clones formed <12 colonies. In SiHa cells, wild-type and sense clones formed approximately 60 colonies after 5 weeks; antisense clones formed 0-3 colonies. In HeLa S3 cells, wild-type and sense clones formed 218-291 colonies in soft agar after 2 weeks; antisense clones formed 14-160 colonies. There was a good correlation between IGF-IR down-regulation level and inhibition of transformation in soft agar. Tumorigenesis in nude mice was strongly inhibited in HeLa S3 and SiHa clones transfected with the antisense. These results indicate that down-regulation of IGF-IR by antisense RNA can reverse the transformed phenotype of human cervical cancer cells, even when harboring malignant type HPVs.     

人乳头瘤病毒16型E6/E7基因shRNA真核表达载体构建及其对人宫颈癌SiHa细胞增殖及迁移能力的影响

目的 构建针对人乳头瘤病毒16型E6/E7基因的shRNA真核表达载体,获得稳定表达干扰质粒的人宫颈癌SiHa细胞系并探讨其对SiHa细胞增殖及迁移能力的影响。方法 合成3条特异性干扰HPV16 E6/E7基因的shRNA片段并定向插入psilencer 2.1-U6 hygro载体,构建重组质粒psilencer 2.1-U6hygro-shE6/E7并转染入人宫颈癌SiHa细胞, Real- time PCR检测转染后细胞E6/E7 mRNA的表达,选择沉默效应最好的重组质粒并用潮霉素B稳筛,获得稳定表达重组质粒的SiHa细胞,并用real time-PCR和Western blot方法进行鉴定;分别运用CCK-8细胞增殖实验和细胞划痕愈合实验检测细胞的增殖及迁移能力。结果　测序证实针对HPV16 E6/E7的shRNA真核表达载体psilencer 2.1-U6 hygro-shE6/E7构建正确;转染psilencer 2.1-U6 hygro-shE6/E7的SiHa细胞HPV16 E6/E7表达明显受抑,同时其增殖及迁移能力也明显受抑制。结论 psilencer 2.1-U6 hygro-shE6/E7真核表达载体的成功构建并获得稳定沉默表达HPV16 E6/E7的人宫颈癌SiHa细胞系,证实沉默表达HPV16 E6/E7的SiHa细胞增殖及迁移能力会明显受到抑制,这为进一步研究HPV 16 E6/E7基因在宫颈癌发生发展过程中的功能奠定了实验基础。     

Activities of E6 Protein of Human Papillomavirus 16 Asian Variant on miR-21 Up-regulation and Expression of Human Immune Response Genes

Background: Variants of human papillomavirus (HPV) show more oncogenicity than do prototypes. TheHPV16 Asian variant (HPV16As) plays a major role in cervical cancer of Asian populations. Some amino acidchanges in the E6 protein of HPV16 variants affect E6 functions such as p53 interaction and host immunesurveillance. This study aimed to investigate activities of HPV16As E6 protein on modulation of expressionof miRNA-21 as well as interferon regulatory factors (IRFs) 1, 3, 7 and c-fos. Materials and Methods: Vectorsexpressing E6 protein of HPV16As (E6D25E) or HPV16 prototype (E6Pro) were constructed and transfected intoC33A cells. HCK1T cells expressing E6D25E or E6Pro were established by transducing retrovirus-containingE6D25E or 16E6Pro. The E6AP-binding activity of E6 and proliferation of the transfected C33A cells weredetermined. MiR-21 and mRNA of interesting genes were detected in the transfected C33A cells and/or theHCK1T cells, with or without treatment by culture medium from HeLa cells (HeLa-CM). Results: E6D25Eshowed binding activity with E6AP similar to that of E6Pro. Interestingly, E6D25E showed a higher activity ofmiR-21 induction than did E6Pro in C33A cells expressing E6 protein. This result was similar to the HCK1Tcells expressing E6 protein, with HeLa-CM treatment. The miR-21 up-regulation significantly corresponded toits target expression. Different levels of expression of IRFs were also observed in the HCK1T cells expressing E6protein. Interestingly, when treated with HeLa-CM, IRFs 1, 3 and 7 as well as c-fos were significantly suppressedin the HCK1T cells expressing E6D25E, whereas those in the HCK1T cells expressing E6Pro were induced. Asimilar situation was seen for IFN-α and IFN-β. Conclusions: E6D25E of the HPV16As variant differed fromthe E6 prototype in its activities on epigenetic modulation and immune surveillance and this might be a keyfactor for the important role of this variant in cervical cancer progression.     

Tumorigenic transformation of primary rat embryonal fibroblasts by human papillomavirus type 8 E7 gene in collaboration with the activated H-ras gene.

Particular types of human papillomavirus (HPV) are associated with skin cancer of epidermodysplasia verruciformis (EV) patients. Here, we show, for the first time, that the E7 gene of EV-associated HPV8 possesses a potential oncogenic transforming ability. The HPV8 E7 open reading frame (ORF) and the HPV16 E7 ORF were cloned under the SV40 promoter/enhancer to construct recombinant plasmids pcD2-8E7 and pcD2-16E7, respectively. Transfection of primary rat embryonal fibroblasts having an activated H-ras gene revealed that pcD2-8E7 as well as pcD2-16E7 induced transformation of cells in G418-resistant colonies at an efficiency of 12.3% and 42.9%, respectively. The resulting transformed cell lines induced by pcD2-8E7 and activated H-ras were tumorigenic when injected into syngeneic immunocompetent rats. The potential tumorigenicity of HPV8 E7 seemed to be higher than that of HPV16 E7.     

Immortalization of human adult prostatic adenocarcinoma cells by human papilloma virus HPV16 and — 18 DNA

Primary prostate epithelial and prostate adenocarcinoma cells cultured in serum-free medium grew for up to 10 passages before senescence. Cells from prostate adenocarcinoma of a 55-year-old patient without lymph node involvement were transfected with plasmids containing recombinant human papilloma virus HPV16 or HPV18 DNA and the selectable neomycinresistance gene. After G-418 selection, cells underwent crisis, and surviving cells infected with retroviruses encoding the HPV18 E6/E7 genes (HPV-PAC1), transfected with a head-to-tail dimer of the complete HPV16 genome (HPV-PAC2), or transfected with HPV18 E6/E7 early genes (HPV-PAC3) were established. HPV-PAC1 and HPV-PAC2 cultures appeared morphologically similar to primary cultures even after 40 passages. However, HPV-PAC2 cultures had a clonal morphology. All lines were positive for cytokeratin 18, had acquired vimentin expression, and contained either HPV16 or HPV18 sequences integrated into host DNA. None was tumorigenic in nude mice or formed colonies in soft agar. These cells did not secrete prostate specific antigen nor respond to androgen although tamoxifen inhibited the growth of the cells. Immunohistochemistry showed no evidence of p53 overexpression. Further characterization of these cell lines and examination of their response to chemotherapeutic agents may provide relevant information for the study of hormone-independent PC.     

HPV18 E6E7 反义荧光真核表达载体的构建及其在宫颈癌HeLa 细胞中的表达

 目的 构建HPV18型E6E7反义荧光真核表达载体,并观察其对宫颈癌HeLa细胞中HPV18 E6和E7基因表达的影响,探索反义技术用于治疗临床HPV感染及宫颈癌的可能性。方法 以HPV18型全基因质粒为模板,PCR法扩增HPV18型E6E7区716bp片段,利用基因重组技术将目的片段反向插入荧光真核表达载体pEGFP-C1,EcoR I酶切并测序鉴定;采用脂转法将重组质粒pEGFP-HPV18 E6E7as（EGFP-18AS）转染宫颈癌HeLa细胞株,通过RT-PCR及western blot检测细胞中E6、E7 mRNA和蛋白的表达。结果 成功构建HPV18E6E7反义荧光真核表达载体EGFP-18AS,经脂质体转染HeLa细胞,48h后在荧光倒置显微镜下可见明显的绿色荧光,且细胞中E6、E7 mRNA及蛋白表达水平均明显下调。结论 反义荧光真核表达载体可以有效的抑制HPV18E6、E7癌基因的表达,为治疗HPV感染和宫颈癌提供了一种新的方法。     

Critical role for D-type cyclins in cellular transformation induced by E6/E7 of human papillomavirus type 16 and E6/E7/ErbB-2 cooperation

Recently, we reported that E6/E7 of human papillomavirus (HPV) type 16 cooperates with the ErbB-2 receptor to induce cellular transformation of human normal oral epithelial (NOE) and mouse normal embryonic fibroblast (NEF) cells. Furthermore, we demonstrated that cyclin D1 is essential for this transformation induced by E6/E7 and E6/E7/ErbB-2 cooperation using cyclin D1 antisense and knockout (D1(-/-)) cells. To determine the role of all D-type cyclins (D1, D2 and D3) in E6/E7/ErbB-2 cooperation, we examined the effects of E6/E7, ErbB-2 alone and E6/E7/ErbB-2 together in NEF, NEF-D1(-/-), NEF-D2(-/-) and NEF-D3(-/-) cells. We confirm that NEF-E6/E7 and NEF-E6/E7/ErbB-2, but not NEF-ErbB-2 cells, induce colony formation in soft agar and tumor formation in nude mice. We report that E6/E7, ErbB-2 and E6/E7/ErbB-2 together all fail to induce neoplastic transformation of D1(-/-) and D2(-/-) cells in vitro and in vivo. In contrast, E6/E7/ErbB-2 together but neither E6/E7 nor ErbB-2 alone provoke cellular transformation of D3(-/-) cells. Nevertheless, D3(-/-)E6/E7/ErbB-2 cells resulted in up to a 60 and 50% decrease in colony and tumor formation in soft agar and nude mice, respectively, compared with NEF-E6/E7/ErbB-2 cells. Furthermore, using cyclin D2 small interfering RNA we inhibited tumor and colony formation of the human NOE-E6/E7-ErbB-2-transformed cell line; in contrast, cyclin D3 small interfering RNA repressed approximately 50% of colony and 40% of tumor formation of E6/E7/ErbB-2 cooperation in this cell line. These data suggest that cyclins D1, D2 and D3 (to a lesser extent) are important downstream mediators of the cellular transformation induced by E6/E7 and E6/E7/ErbB-2 cooperation in normal cells. Our data imply that anti-D-type cyclin therapies are important in the treatment of human cancers expressing high-risk HPV or HPV/ErbB-2.     

Human papillomavirus type 16 E7 oncoprotein causes a delay in repair of DNA damage

Background and purposePatients with human papillomavirus related (HPV+) head and neck cancers (HNCs) demonstrate improved clinical outcomes compared to traditional HPV negative (HPV−) HNC patients. We have recently shown that HPV+ HNC cells are more sensitive to radiation than HPV− HNC cells. However, roles of HPV oncogenes in regulating the response of DNA damage repair remain unknown.Material and methodsUsing immortalized normal oral epithelial cell lines, HPV+ HNC derived cell lines, and HPV16 E7-transgenic mice we assessed the repair of DNA damage using γ-H2AX foci, single and split dose clonogenic survival assays, and immunoblot. The ability of E7 to modulate expression of proteins associated with DNA repair pathways was assessed by immunoblot.ResultsHPV16 E7 increased retention of γ-H2AX nuclear foci and significantly decreased sublethal DNA damage repair. While phospho-ATM, phospho-ATR, Ku70, and Ku80 expressions were not altered by E7, Rad51 was induced by E7. Correspondingly, HPV+ HNC cell lines showed retention of Rad51 after γ-radiation.ConclusionsOur findings provide further understanding as to how HPV16 E7 manipulates cellular DNA damage responses that may underlie its oncogenic potential and influence the altered sensitivity to radiation seen in HPV+ HNC as compared to HPV− HNC.     

Short-term induction and long-term suppression of HPV16 oncogene silencing by RNA interference in cervical cancer cells

RNA interference-mediated gene silencing has the potential to block gene expression. A synthetic double-stranded small interfering RNA (siRNA) based on a sequence motif of 21 nucleotides from human papillomavirus 16 (HPV16) E6E7 bicistronic RNA was found to be a potent siRNA that suppresses expression of both the E6 and E7 oncogenes in HPV16+ CaSki and SiHa cells. When stably expressed as a short hairpin RNA in these cells, however, siRNA silencing of E6 and E7 expression was efficient only at early cell passages, but became inefficient with increased cell passages despite the continued expression of the siRNA at the same level. The loss of the siRNA function was duplicable in stable p53 siRNA cells, but not in stable lamin A/C siRNA cells, suggesting that it is gene selective. The cells resistant to siRNA function retained normal siRNA processing, duplex unwinding and degradation of the unwound sense strand and RNA-induced silencing complex formation, suggesting that loss of the siRNA function occurred at a later step. Surprisingly, the siRNA-resistant cells were found to express notably a cytoplasmic protein of approximately 50 kDa that specifically and characteristically interacted with the unwound, antisense strand E7 siRNA. Altogether, our data indicate that a potent siRNA targeting to an essential or regulatory gene might induce a cell to develop siRNA-suppressive function.     

High-risk human papillomavirus E7 expression reduces cell-surface MHC class I molecules and increases susceptibility to natural killer cells

High-risk human papillomavirus (HPV) is a major causative agent of cervical cancer and the E6 and E7 genes encode the major HPV oncoproteins. The E7 protein from high-risk HPV types alters cell cycle progression and represses genes encoding components of the antigen-presentation pathway, suggesting a role for E7 in tumour immune evasion. We show that knockdown of E7 expression in HPV16- and HPV18-transformed cervical carcinoma cells by RNA interference increased expression of major histocompatibility complex (MHC) class I at the cell surface and reduced susceptibility of these cells to natural killer (NK) cells. Tetracycline-regulated induction of HPV16 E7 resulted in reduced expression of cell surface MHC class I molecules and increased NK cell killing. Our results suggest that, for HPV-associated malignancies, reduced MHC class I expression is the result of an active immune evasion strategy that has evolved to assist viral replication.