The E6 and E7 proteins of the cutaneous human papillomavirus type 38 display transforming properties

Several studies have suggested the involvement of cutaneous human papillomaviruses (HPVs) in the development of nonmelanoma skin cancers. Here we have characterized the in vitro properties of E7 proteins of three cutaneous HPV types, 10, 20, and 38, which are frequently detected in skin specimens. We show that HPV38 E7 is able to inactivate the tumor suppressor pRb and induces loss of G(1)/S transition control, a key event in carcinogenesis. In contrast, HPV10 and HPV20 E7 proteins do not display these in vitro transforming activities. We also show that the two early proteins E6 and E7 of HPV38 are sufficient to corrupt the cell cycle and senescence programs in primary cells, inducing active and long-lasting proliferation of primary human keratinocytes, the natural host cells. Our study shows that E6 and E7 of this cutaneous HPV type have transforming activity in primary human cells, suggesting a role for HPV38 infection in skin carcinogenesis. In further support of such a role, we detected HPV38 DNA in approximately 50% of nonmelanoma skin cancers, but only in 10% of healthy skin specimens (P < 0.001).     

Evaluation of the prevalence of human papillomavirus and Epstein-Barr virus in esophageal squamous cell carcinomas

The aim of this study was to determine the possible involvement of human papillomavirus and Epstein-Barr virus in esophageal squamous cell cancer (ESCC) carcinogenesis in the Greek population. DNA was extracted from 30 ESCC and 27 normal esophageal specimens and screened for HPV type-specific or EBV infection by PCR-based assay. Seventeen out of 30 ESCC specimens (56%) were found positive for HPV DNA, of which 15 (88%) were typed as HPV-18 infected, one (5.9%) as HPV-16 infected, and one (5.9%) as infected by an HPV type different from the studied HPV-6, 11, 16, 18 and 33 subtypes. Six of the 27 normal esophageal specimens (22.2%) were positive for HPV infection, five typed as HPV-18 (83.3%) and one as HPV-16 (16.7%). All samples were negative for EBV genome detection as assessed by the PCR assay. No statistically significant correlation was found between the HPV status of the tumor samples and clinical parameters including sex, age of the patients, tobacco or alcohol use, differentiation grade of the lesions and stage of the disease. In conclusion, our findings indicate a statistically significant (p<0.001) overall association between ESCC and HPV infection, mostly related to the HPV-18 subtype, in the Greek population.     

HPV感染、FHIT蛋白表达与非小细胞肺癌的相关性研究

目的探讨人乳头瘤病毒感染在NSCLC发生中的病因学意义,同时分析FHIT蛋白表达与NSCLC发生及HPV感染的关系.方法采用PCR方法选用通用型引物和HPV16、18型特异性引物分别对42例NSCLC及14例肺良性病变组织进行检测.免疫组化SP法检测FHIT蛋白的表达水平.结果 HPV DNA检出率肺癌组为42.9%,肺良性病变组为7.1%,二者有显著性差异(P<0.05).HPV感染率在肺鳞癌(53.6%)显著高于腺癌(21.4%),且随着分化程度降低,其感染率增高,在吸烟患者(57.7%)显著高于不吸烟患者(18.8%);FHIT蛋白异常表达率肺癌组为61.9%,与肺良性病变组(28.6%)比较有显著性差异(P<0.05).肺癌中HPV阳性组FHIT蛋白异常表达率为83.3%,明显高于HPV阴性组(45.8%,P<0.05).结论 HPV感染与NSCLC组织学类型、分化程度及吸烟有关,它可能是导致NSCLC发生的重要病因学因素之一;FHIT蛋白异常表达与NSCLC发生及HPV感染有关,HPV可能通过诱导FHIT表达异常参与NSCLC的发生发展过程.     

乌鲁木齐地区乳腺癌与人乳头瘤病毒亚型感染的相关性研究

目的：对本地区乳腺癌患者癌组织进行人乳头瘤病毒（HPv）检测,对HPV亚型与乳腺癌的相关性进行研究。方法：选择本地区2010年1月-2013年1月182例乳腺癌患者作为研究组,同时选择30例乳腺良性肿瘤患者作为对照组,均分型基因芯片检测系统对提取的DNA进行分型检测。观察两组患者HPV感染情况及感染亚型。结果：两组患者HPV阳性病例67例,其中研究组阳性66例,阳性率为36．26％,对照组阳性1例,阳性率为3-33％;研究组阳性率明显高于对照组,两组比较差异具有显著性（P〈0．05）。亚型检测结果显示,共检出7种HPV亚型,其中高危型5种,分别为HPV16、HPV18、HPV58、HPV51和HPV56型,低危型两种,分别为HPV6、11两种。研究组高危型61例,低危型5例,对照组1例为HPV6。Ⅰ期、Ⅱ期、Ⅲ期、Ⅳ期乳腺癌患者HPV阳性率分别为16．28％、19．71％、62％、100％,Ⅲ期、Ⅳ期患者的阳性率明显高于Ⅰ期、Ⅱ期,不同分期阳性率比较差异具有显著性（P〈0．05）。结论：乳腺癌患者癌组织中HPV阳性率明显偏高,且绝大多数为高危亚型,而且HPV阳性率与病理分期呈正相关,说明本地区HPV感染与乳腺癌的发生与发展具有一定的相关性,两者的相关性还有待进一步探索。     

Computer-assisted analysis of p53 and PCNA expression in oral lesions infected with human papillomavirus

OBJECTIVE: To carry out a retrospective study to determine whether human papillomavirus (HPV) infection and immunohistochemical expression of p53 and proliferating cell nuclear antigen (PCNA) are related to the risk of oral cancer. STUDY DESIGN: Fifty-seven oral biopsies, consisting of 30 oral squamous papillomas (OSPs) and 27 oral squamous cell carcinomas (OSCCs) were tested for the presence of HPV 6/11 and 16/18 by in situ hybridization using catalyzed signal amplification and in situ hybridization. p53 And PCNA expression was analyzed by immunohistochemistry and evaluated quantitatively by image analysis. RESULTS: Nineteen of the 57 oral lesions (33.3%) were positive for HPV. HPV 6/11 was found in 6 of 30 (20%) OSPs and 1 of 27 (3.7%) OSCCs. HPV 16/18 was found in 10 of 27 (37%) OSCCs and 2 of 30 (6.7%) OSPs. Sixteen of the 19 HPV-positive cases (84.2%) were p53 negative; 5 (9%) were HPV 6/11 and 11 (19%) HPV 16/18, with an inverse correlation between the presence of HPV DNA and p53 expression (P = .017, P < .05). PCNA expression appeared in 18 (94.7%) of HPV positive cases, showing that HPV 16/18 was associated with intensity of PCNA expression and with OSCCs (P = .037, P < .05). CONCLUSION: Quantitative evaluation of p53 by image analysis showed an inverse correlation between p53 expression and HPV presence, suggesting protein degradation. Image analysis also demonstrated that PCNA expression was more intense in HPV DNA 16/18 OSCCs. These findings suggest involvement of high-risk HPV types in oral carcinogenesis.     

HPV与喉癌研究新进展

头颈部肿瘤(Head and Neck Cancer,HNC)包括口腔,咽部,鼻腔以及喉部的肿瘤,拥有较高的发病率和复杂的发病机制。而在所有头颈部肿瘤中,喉癌占所有恶性肿瘤中的3%以上,是全球第六大最常见的恶性肿瘤,因此喉癌在所有HNC中应受到特殊的关注。人乳头瘤病毒(human papillomavirus,HPV)是小的双链DNA病毒。已有大量研究表明HPV感染与多种肿瘤的发生及预后密切相关。而目前HPV感染对HNC,尤其是对于口咽部肿瘤的致癌作用和临床意义引起学者们的重视,但是HPV感染对喉癌的作用目前尚未阐明。因此我们回顾了近年来关于HPV感染与喉癌相关性及其潜在致癌性的研究。尽管目前对于HPV在喉癌中的检出率多中心研究结果存在一定差异,但初步的研究已经表明HPV高危亚型的感染,如HPV16和HPV18等,与喉癌的发生存在一定的相关性,HPV病毒DNA与肿瘤细胞存在基因整合,同时喉癌细胞中P16的表达增高。但针对HPV感染后导致的相关疾病的预防及可行的精准性治疗措施目前尚不十分明确,还有待于进一步研究。     

Genetic Variation of Human Papillomavirus Type 16 in Individual Clinical Specimens Revealed by Deep Sequencing

Viral genetic diversity within infected cells or tissues, called viral quasispecies, has been mostly studied for RNA viruses, but has also been described among DNA viruses, including human papillomavirus type 16 (HPV16) present in cervical precancerous lesions. However, the extent of HPV genetic variation in cervical specimens, and its involvement in HPV-induced carcinogenesis, remains unclear. Here, we employ deep sequencing to comprehensively analyze genetic variation in the HPV16 genome isolated from individual clinical specimens. Through overlapping full-circle PCR, approximately 8-kb DNA fragments covering the whole HPV16 genome were amplified from HPV16-positive cervical exfoliated cells collected from patients with either low-grade squamous intraepithelial lesion (LSIL) or invasive cervical cancer (ICC). Deep sequencing of the amplified HPV16 DNA enabled de novo assembly of the full-length HPV16 genome sequence for each of 7 specimens (5 LSIL and 2 ICC samples). Subsequent alignment of read sequences to the assembled HPV16 sequence revealed that 2 LSILs and 1 ICC contained nucleotide variations within E6, E1 and the non-coding region between E5 and L2 with mutation frequencies of 0.60% to 5.42%. In transient replication assays, a novel E1 mutant found in ICC, E1 Q381E, showed reduced ability to support HPV16 origin-dependent replication. In addition, partially deleted E2 genes were detected in 1 LSIL sample in a mixed state with the intact E2 gene. Thus, the methods used in this study provide a fundamental framework for investigating the influence of HPV somatic genetic variation on cervical carcinogenesis.     

Detection of Human Papillomavirus DNA in Patients with Breast Tumor in China

The presence of HPV in breast tissue and the potential causal association between human papillomavirus (HPV) and breast cancer (BC) remains controversial. The aim of the present study was to compare the HPV prevalence in BC tissues, adjacent normal breast tissues and breast benign disease tissues and to investigate the possible association between HPV and breast tumor development in Chinese women. Paraffin-embedded specimens from 187 pairs of BCs including tumor and normal breast tissue adjacent to tumors and 92 breast benign lesions between June 2009 and July 2014 were investigated by nested polymerase chain reaction (PCR) and type-specific PCR, respectively. With strictly quality control, HPV positive infection was detected in three BC tissues. No HPV positive infection was detected in all normal breast tissue adjacent to tumors and benign breast tissues. Through our detailed analysis, rare HPV infection in this study suggests that HPV might not be associated with BC progression.     

NF-kappaB protects human papillomavirus type 38 E6/E7-immortalized human keratinocytes against tumor necrosis factor alpha and UV-mediated apoptosis

Constitutive activation of NF-κB signaling is a key event in virus- and non-virus-induced carcinogenesis. We have previously reported that cutaneous human papillomavirus type 38 (HPV38) displays transforming properties in in vitro and in vivo experimental models. However, the involvement of NF-κB signaling in HPV38-induced cell growth transformation remains to be determined. In this study, we showed that HPV38 E6 and E7 activate NF-κB and that inhibition of the pathway with the IκBα superrepressor sensitizes HPV38E6E7-immortalized human keratinocytes to tumor necrosis factor alpha (TNF-α)- and UVB radiation-mediated apoptosis. Accordingly, inhibition of NF-κB signaling resulted in the downregulation of NF-κB-regulated antiapoptotic genes, including cIAP1, cIAP2, and xIAP genes. These findings demonstrate a critical role of NF-κB activity in the survival of HPV38E6E7-immortalized human keratinocytes exposed to cytokine or UV radiation. Our data provide additional evidence for cooperation between beta HPV infection and UV irradiation in skin carcinogenesis.     

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.     

Prevalence of human papillomavirus and Epstein-Barr virus DNA in penile cancer cases from Brazil

Penile cancer is a potentially mutilating disease. Although its occurrence is relatively rare worldwide, penile cancer rates can be high in developing countries. A few studies have been conducted on the involvement of human papillomavirus (HPV) in penile carcinoma, which have found HPV present in 30-70% of penile malignant lesions, with a higher prevalence of HPV 16 and 18. It has been assumed that cofactors, such as Epstein-Barr virus (EBV) infections, may play a role in the progression of penile neoplasia. The aim of this study was to determine HPV and EBV prevalence in 135 penile malignant lesions from Brazilian men through the use of MY09/11 polymerase chain reaction (PCR), type-specific PCR and restriction fragment length polymorphism analysis. HPV prevalence among the men tested was 60.7%. Of the men who tested positive, 27 presented with HPV 16 (29.7%), five with HPV 18 (5.5%), 21 with HPV 45 (23.1%) and nine with HPV 6 (9.9%). Seven mixed infections were detected (9.2%), while 11 cases remained untyped (13.4%). Regarding EBV positivity, 46.7% of the samples contained EBV DNA with EBV-1 as the most prevalent type (74.6%). More than 23% of the men were co-infected with both HPV and EBV, while 35% presented exclusively with HPV DNA and 20% presented only with EBV DNA. Penile carcinoma aetiology has not been fully elucidated and the role of HPV and EBV infections individually or synergistically is still controversial. Hence, more studies are needed to determine their possible role in carcinogenesis.     

Presence of Human Papillomavirus DNA in Malignant Neoplasia and Non-Malignant Breast Disease

Breast cancer is the leading cause of cancer death among women worldwide. Multiple extrinsic and intrinsic factors are associated with this disease’s development. Various research groups worldwide have reported the presence of human papillomavirus (HPV) DNA in samples of malignant breast tumors. Although its role in mammary carcinogenesis is not fully understood, it is known that the HPV genome, once inserted into host cells, has oncogenic capabilities. The present study aimed to detect the presence of HPV DNA in 116 breast tissue biopsies and classify them according to their histology. It was found that 50.9% of the breast biopsies analyzed were malignant neoplasms, of which 74.6% were histologically classified as infiltrating ductal carcinoma. In biopsies with non-malignant breast disease, fibroadenoma was the most common benign neoplasm (39.1%). Detection of HPV DNA was performed through nested PCR using the external primer MY09/11 and the internal primer GP5+/6+. A hybridization assay genotyped HPV. HPV DNA was identified in 20.3% (12/59) of malignant neoplasms and 35% non-malignant breast disease (16/46). It was also detected in 27.3% (3/11) of breast tissue biopsies without alteration. However, there are no statistically significant differences between these groups and the existence of HPV DNA (p = 0.2521). Its presence was more frequent in non-malignant alterations than in malignant neoplasias. The most frequent genotypes in the HPV-positive samples were low-risk (LR) HPV-42 followed by high-risk (HR) HPV-31.     

HPV18 E7致癌蛋白的高效表达、纯化和鉴定

目的为进一步研究人乳头状瘤病毒18（Human papillomavirus18,HPV18）E7蛋白的结构与功能。方法构建HPV18 E7的谷胱甘肽S-转移酶融合蛋白质粒pGEX-6P-1-GST-HPV18 E7,重组质粒转入大肠埃希菌BL21进行可溶性融合蛋白的高效表达。结果柱上切除法去除GST标签,表达产物经glutathione Sepharose 4B亲和层析纯化,获得了SDS-PAGE和HPLC-ESI-MS纯度的HPV18 E7均质蛋白,非变性PAGE和凝胶过滤表明HPV18 E7以稳定的单体形式存在于水溶液中。高压液相色谱-电喷雾质谱（HPLC-ESI-MS）分析得到HPV18 E7精确分子量为12865．0 Da,与其理论值吻合。纯化蛋白经HPLC-ESI-MS／MS鉴定为目的产物,鉴定出的9个匹配肽段覆盖率为HPV18 E7整个氨基酸序列的96．5％。结论本文所建立的技术可以有效地大量制备HPV18 E7,为进一步研究其结构与功能和致癌机制奠定了重要的物质基础。     

四川地区宫颈癌HPV59型感染及其E6基因突变

宫颈癌是妇科常见的恶性肿瘤,特定型别的人 乳头瘤病毒(HPV)感染是引发宫颈癌的主要因 素。根据HPV致癌性的不同可分为高危型,低 危型。Munoz N[2]等对来自9个国家的1918例宫 颈癌组织进行各型HPV筛查,最终确认HPV-16、 18、26、31、33、35、39、45、51、52、53、56、58、59、66、 68、73及82型为高危型。李洁等[3]用核酸印迹技 术对1986至1994年间来自我国14个省市自治区 的1008宫颈癌组织进行HPV型别检测,发现 HPV-16、18、31、35、51、58等型的存在,并发现各 地区主要流行型别随地理位置有所差异。     

Human papillomavirus (HPV) oncoprotein E6 facilitates Calcineurin-Nuclear factor for activated T cells 2 (NFAT2) signaling to promote cellular proliferation in cervical cell carcinoma

The calcineurin-NFAT signaling pathway regulates cell proliferation, differentiation, and development in diverse cell types and organ systems. Deregulation of calcineurin-NFAT signaling has been reported in leukaemias and few solid tumors such as breast and colon. In the present study, we found elevated calcineurin protein levels and phosphatase activity in cervical cancer cell lines and depletion of the same attenuated cell proliferation. Additionally, nuclear levels of NFAT2, a downstream target of calcineurin, viz, was found elevated in human papillomavirus (HPV) infected cells, HeLa and SiHa, compared to the HPV negative cells, HaCaT and C33A, indicative of its higher DNA binding activity. The nuclear levels of both NFAT1 and NFAT3 remain unaltered implicating they have little role in cervical carcinogenesis. Similar to the in vitro studies, the HPV infected human squamous cell carcinoma specimens showed higher NFAT2 levels compared to the normal cervical epithelium. Depletion of NFAT2 by RNAi attenuated growth of SiHa cells. Overexpression of HPV16 oncoproteins viz, E6 and E7 increased NFAT2 expression levels and DNA binding activity, while knockdown of E6 by RNAi decreased the same. Briefly, we now report an activation of calcineurin-NFAT2 axis in cervical cancer and a novel role of HPV oncoprotein in facilitating NFAT2 dependent cell proliferation.     

Inhibition of DNA replication of human papillomavirus by artificial zinc finger proteins

Recently, we demonstrated that plant DNA virus replication was inhibited in planta by using an artificial zinc finger protein (AZP) and created AZP-based transgenic plants resistant to DNA virus infection. Here we apply the AZP technology to the inhibition of replication of a mammalian DNA virus, human papillomavirus type 18 (HPV-18). Two AZPs, designated AZP(HPV)-1 and AZP(HPV)-2, were designed by using our nondegenerate recognition code table and were constructed to block binding of the HPV-18 E2 replication protein to the replication origin. Both of the newly designed AZPs had much higher affinities towards the replication origin than did the E2 protein, and they efficiently blocked E2 binding in vitro. In transient replication assays, both AZPs inhibited viral DNA replication, especially AZP(HPV)-2, which reduced the replication level to approximately 10%. We also demonstrated in transient replication assays, using plasmids with mutant replication origins, that AZP(HPV)-2 could precisely recognize the replication origin in mammalian cells. Thus, it was demonstrated that the AZP technology could be applied not only to plant DNA viruses but also to mammalian DNA viruses.     

mRNA and DNA Detection of Human Papillomaviruses in Women of All Ages Attending Two Colposcopy Clinics

Objective

HPV infection is a common finding, especially in young women while the majority of infections are cleared within a short time interval. The aim of this study was to examine the efficacy of HPV DNA and mRNA testing in a population attending colposcopy units of two University hospitals.

Methods

1173 liquid based cervical samples from two colposcopy clinics were tested for HPV DNA positivity using a commercial typing kit and HPV E6/E7 mRNA positivity with a flow cytometry based commercial kit. Statistic measures were calculated for both molecular tests and morphological cytology and colposcopy diagnosis according to histology results.

Results

HPV DNA, high-risk HPV DNA, HPV16 or 18 DNA and HPV mRNA was detected in 55.5%, 50.6%, 20.1% and 29.7% of the cervical smears respectively. Concordance between the DNA and the mRNA test was 71.6% with their differences being statistically significant. Both tests’ positivity increased significantly as lesion grade progressed and both displayed higher positivity rates in samples from women under 30 years old. mRNA testing displayed similar NPV, slightly lower sensitivity but significantly higher specificity and PPV than DNA testing, except only when DNA positivity for either HPV16 or 18 was used.

Conclusions

Overall mRNA testing displayed higher clinical efficacy than DNA testing, either when used as a reflex test or as an ancillary test combined with morphology. Due to enhanced specificity of mRNA testing and its comparable sensitivity in ages under 25 or 30 years old, induction of mRNA testing in young women could be feasible if a randomized trial verifies these results.     

Increased migration of Langerhans cells in response to HPV16 E6 and E7 oncogene silencing: role of CCL20

Human papillomavirus (HPV) infection, particularly type 16, is causally associated with cancer of the uterine cervix. The persistence or progression of cervical lesions suggests that viral antigens are not adequately presented to the immune system. This hypothesis is reinforced by the observation that most squamous intraepithelial lesions (SILs) show quantitative and functional alterations of Langerhans cells (LC). The infiltration of immature LC in the squamous epithelium is mainly controlled by Macrophage Inflammatory Protein 3α/CCL20. After having shown that CCL20 production is altered in HPV-transformed keratinocytes (KC), the possible role of HPV16 E6 and E7 viral oncoproteins in the reduced CCL20 levels observed in SILs was investigated by silencing HPV16 E6 and E7 oncogenes by RNA interference (siRNA). This treatment not only increased CCL20 secretion but also resulted in the modulation of NF-κB p50, p52 and p65 precursor localization. Moreover, silencing of E6 and E7 oncogenes in HPV16-transformed KC induced a significantly higher migratory capacity of LC in a Boyden chamber assay and in an in vitro formed (pre)neoplastic epithelium reminiscent of high-grade SILs. Anti-CCL20 neutralizing antibody experiments showed that the increased migration of LC is due to the re-expression of CCL20 in E6 and E7 siRNA transfected KC. These data suggest that HPV16 E6/E7-induced down-regulation of CCL20 observed during the cervical carcinogenesis may contribute to a diminished capacity of the immune system to control HPV infection. P. Hubert and J. H. Caberg contributed equally to this work.     

Viral load of HPV 16/18 in esophageal squamous cell carcinoma in three ethnic groups living in Xinjiang Autonomous Region, China

To investigate the viral load of human papillomavirus (HPV) in esophageal squamous cell carcinoma (ESCC) patients from three ethnic groups in Xinjiang. Using Gp5+/Gp6+ consensus primers, the prevalence of HPV DNA was examined in 253 paraffin-embedded ESCC samples. The presence and viral load of HPV 16 and HPV 18 were detected in Kazakhs, Uygurs and Hans using type-specific primers by quantitative real-time PCR (qRT-PCR). Among the 253 ESCC samples, 52 cases were positive for HPV DNA, all the 52 positive cases displayed HPV 16 infection, and six of the 52 cases were co-infected by HPV 16 and 18. HPV 16-positive rate and viral load were higher in lesions, and was inversely correlated with differentiation grades. However, there was no statistic significance among different differentiation grades. Also, there were no significant difference between detection rates of HPV types, viral load and age, gender, ethnic group, and lymph node metastasis. HPV 16 and HPV 18 genotypes could simultaneously be detected in ESCC specimens in three main ethnic groups in Xinjiang. The viral load of HPV 16 is higher in the ESCC lesions, and is inversely correlated with the differentiation grades. These observations reinforce the suggestion that HPV infection may involved in ESCC carcinogenesis; however, high prevalence or viral load of HPV infection does not seem to be related with high incidence of ESCC in Kazakhs, which may be the one element among the multiple risk factors contributing to ESCC.     

In vivo and in vitro studies evaluating the chemopreventive effect of metformin on the aryl hydrocarbon receptor-mediated breast carcinogenesis

Metformin (MET) is a clinically used anti-hyperglycemic agent that shows activities against chemically-induced animal models of cancer. A study from our laboratory showed that MET protectes against 7, 12-dimethylbenz[a]anthracene (DMBA)-induced carcinogenesis in vitro human non-cancerous epithelial breast cells (MCF10A) via activation of the aryl hydrocarbon receptor (AhR). However, it is unclear whether MET can prevent the initiation of breast carcinogenesis in an in vivo rat model of AhR-induced breast carcinogenesis. Therefore, the main aims of this study are to examine the effect of MET on protecting against rat breast carcinogenesis induced by DMBA and to explore whether this effect is medicated through the AhR pathway. In this study, treatment of female rats with DMBA initiated breast carcinogenesis though inhibiting apoptosis and tumor suppressor genes while inducing oxidative DNA damage and cell cycle proliferative markers. This effect was associated with activation of AhR and its downstream target genes; cytochrome P4501A1 (CYP1A1) and CYP1B1. Importantly, MET treatment protected against DMBA-induced breast carcinogenesis by restoring DMBA effects on apoptosis, tumor suppressor genes, DNA damage, and cell proliferation. Mechanistically using in vitro human breast cancer MCF-7 cells, MET inhibited breast cancer stem cells spheroids formation and development by DMBA, which was accompanied by a proportional inhibition in CYP1A1 gene expression. In conclusion, the study reports evidence that MET is an effective chemopreventive therapy for breast cancer by inhibiting the activation of CYP1A1/CYP1B1 pathway in vivo rat model.