Epstein-Barr病毒在肝细胞癌发生中的作用探讨

目的:了解肝细胞癌(hepatocellular carcinoma,HCC)患者的EpsteinBarr病毒(EBV)感染情况,探讨EBV与肝炎病毒有无协同致癌作用。方法:研究组为78例HCC石蜡标本,对照组为26例非癌症肝组织标本。用PCR检测EBVDNA(BamHIW,LMP1)、HBVDNA(S基因、Χ基因),用RTPCR检测HCVRNA和HDVRNA,用免疫组化检测EBV(LMP1)、HBV(HBsAg、HbcAg)和HCV。结果:EBVDNA在HCC组阳性率高于对照组(28.2%vs8.0%),χ2=4.622,P=0.032;HBVDNA在HCC组阳性率高于对照组(56.4%vs23.1%),χ2=8.681,P=0.008;EBV与HBV在HCC组无相关关系,χ2=0.835,P=0.375。HCVRNA、HDVRNA在18例HCC中阳性分别为1和0例。免疫组化测EBV在HCC组阳性率高于对照组(32.1%vs2.5%),χ2=6.02,P=0.012;HBV在HCC组阳性率高于对照组(57.7%vs5.1%),χ2=10.03,P=0.001。结论:EBV在HCC发生中可能起作用,与HBV无明显协同致癌作用;HCV、HDV检出率不高,与EBV关系未能确定。     

Smad4 expression in hepatocellular carcinoma differs by hepatitis status

Aims: Primary hepatocellular carcinoma (HCC) is a common malignancy often related to hepatitis viralinfection. Smad4 is known to mediate the TGF-β pathway to suppress tumorigenesis. However, the function ofSmad4 in HCC is still controversial. In this study we compared levels of Smad4 in HCC tissues with or withouthepatitis virus infection and adjacent normal-appearing liver. Methods: Samples from HCC patients wereanalyzed for Smad4 protein and mRNA expression by immunohistochemistry (IHC), RT-PCR and Westernblotting. Results: We found that tumor tissues expressed less Smad4 mRNA and protein than the adjacent tissues.Most HCC tumor tissues were negative for Smad4 in IHC staining, while the majority of adjacent tissues werepositively stained. Interestingly, protein levels were higher in HCC tissues with viral hepatitis than those withoutvirus infection. Suppression of expression appeared closely related to HCC, so that Smad4 appears to functionas a tumor suppressor gene (TSG). Conclusion: Patients with hepatitis viral infection, at higher risk for HCC,exhibited increased Smad4 protein expression suggesting hepatitis virus may modulate Smad4 expression, whichis functionally distinct from its putative role as a TSG. Smad4 expression may thus be an applicable marker fordiagnosis and/or a target to develop therapeutic agents for HCC.     

Silencing of human papillomavirus (HPV) E6/E7 oncogene expression affects both the contents and the amounts of extracellular microvesicles released from HPV‐positive cancer cells

The human papillomavirus (HPV) E6/E7 oncogenes play a crucial role in the HPV‐induced carcinogenesis. In this study, the authors investigated whether silencing of endogenous HPV E6/E7 expression may influence the contents or amounts of extracellular microvesicles (eMVs) released from HPV‐positive cancer cells. It was found that eMVs secreted from HeLa cells are enriched for Survivin protein. RNA interference studies revealed that maintenance of both intracellular and microvesicular Survivin amounts was strongly dependent on continuous E6/E7 expression. This indicates that intracellular HPV activities are translated into visible alterations of protein contents in eMVs. Besides Survivin, eMVs from HeLa cells contain additional members of the inhibitor of apoptosis protein (IAP) family (XIAP, c‐IAP1 and Livin). In contrast, no evidence for the presence of the HPV E6 and E7 oncoproteins in eMVs was obtained. Moreover, it was found that silencing of HPV E6/E7 expression led to a significant increase of exosomes—representing eMVs of endocytic origin—released from HeLa cells. This effect was associated with the reinduction of p53, stimulation of the p53 target genes TSAP6 and CHMP4C that can enhance exosome production and induction of senescence. Taken together, these results show that silencing of HPV E6/E7 oncogene expression profoundly affects both the composition and amounts of eMVs secreted by HPV‐positive cancer cells. This indicates that HPVs can induce molecular signatures in eMVs that may affect intercellular communication and could be explored for diagnostic purposes.     

Enhancement of immunogenicity of a therapeutic cervical cancer DNA‐based vaccine by co‐application of sequence‐optimized genetic adjuvants

Treatment of patients with cervical cancer by conventional methods (mainly surgery, but also radiotherapy and chemotherapy) results in a significant loss in quality of life. A therapeutic DNA vaccine directed to tumor‐specific antigens of the human papilloma virus (HPV) could be an attractive treatment option. We have developed a nontransforming HPV‐16 E7‐based DNA vaccine containing all putative T cell epitopes (HPV‐16 E7SH). DNA vaccines, however, are less immunogenic than protein‐ or peptide‐based vaccines in larger animals and humans. In this study, we have investigated an adjuvant gene support of the HPV‐16 E7SH therapeutic cervical cancer vaccine. DNA encoded cytokines (IL‐2, IL‐12, GM‐CSF, IFN‐γ) and the chemokine MIP1‐α were co‐applied either simultaneously or at different time points pre‐ or post‐E7SH vaccination. In addition, sequence‐optimized adjuvant genes were compared to wild type genes. Three combinations investigated lead to an enhanced IFN‐γ response of the induced T cells in mice. Interestingly, IFN‐γ secretion of splenocytes did not strictly correlate with tumor response in tumor regression experiments. Gene‐encoded MIP‐1α applied 5 days prior to E7SH‐immunization combined with IFN‐γ or IL‐12 (3 days) or IL‐2 (5 days) postimmunization lead to a significantly enhanced tumor response that was clearly associated with granzyme B secretion and target cells lysis. Our results suggest that a conditioning application and combination with adjuvant genes may be a promising strategy to enhance synergistically immune responses by DNA immunization for the treatment of cervical cancer. © 2009 UICC     

Cutaneous human papillomavirus 88: remarkable differences in viral load

A human papillomavirus (HPV) was cloned from a patient with multiple squamous cell carcinomas (SCCs) and identified as HPV88, recently categorized into a new species within the genus Gamma. The HPV88 viral load in an SCC of the index patient exceeded 1 million copies/cell. By contrast, a survey of 447 skin lesions (79 actinic keratoses, 73 seborrhoeic keratoses, 169 basal cell carcinomas and 126 SCCs) and 362 healthy skin biopsies found detectable HPV88 DNA in only 7 specimens. All these had very low viral loads (<1 copy/10(3) cells) implying extreme biological variability in viral load.     

Exosome Biogenesis,Regulation, and Function in Viral Infection

Exosomes are extracellular vesicles released upon fusion of multivesicular bodies (MVBs) with the cellular plasma membrane. They originate as intraluminal vesicles (ILVs) during the process of MVB formation. Exosomes were shown to contain selectively sorted functional proteins, lipids, and RNAs, mediating cell-to-cell communications and hence playing a role in the physiology of the healthy and diseased organism. Challenges in the field include the identification of mechanisms sustaining packaging of membrane-bound and soluble material to these vesicles and the understanding of the underlying processes directing MVBs for degradation or fusion with the plasma membrane. The investigation into the formation and roles of exosomes in viral infection is in its early years. Although still controversial, exosomes can, in principle, incorporate any functional factor, provided they have an appropriate sorting signal, and thus are prone to viral exploitation. This review initially focuses on the composition and biogenesis of exosomes. It then explores the regulatory mechanisms underlying their biogenesis. Exosomes are part of the endocytic system, which is tightly regulated and able to respond to several stimuli that lead to alterations in the composition of its sub-compartments. We discuss the current knowledge of how these changes affect exosomal release. We then summarize how different viruses exploit specific proteins of endocytic sub-compartments and speculate that it could interfere with exosome function, although no direct link between viral usage of the endocytic system and exosome release has yet been reported. Many recent reports have ascribed functions to exosomes released from cells infected with a variety of animal viruses, including viral spread, host immunity, and manipulation of the microenvironment, which are discussed. Given the ever-growing roles and importance of exosomes in viral infections, understanding what regulates their composition and levels, and defining their functions will ultimately provide additional insights into the virulence and persistence of infections.     

Antibody to human papilloma virus in Danish dentists

Abstract — The aim of this study was to investigate the seroprevalence of antibody to human papilloma virus (HPV) among Danish dentists in order to determine whether this virus constitutes an occupational hazard for dentists. Serum samples from 452 Danish dentists were tested for antibody against a common capsid antigen to HPV by a complement fixation reaction. Nine (2.0%) were seropositive. Dentists'odds ratio for seropositivity was after adjustment for age 0.6 (90% confidence interval: 0.3–1.4) compared to that of voluntary blood donors. In conclusion, Danish dentists do not seem to be at an increased risk of becoming infected with HPV.