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Aberrant expression and constitutive activation of STAT3 in cervical carcinogenesis: implications in high-risk human papillomavirus infection.

ABSTRACT: BACKGROUND: Recent observations indicate potential role of transcription factor STAT3 in cervical cancer development but its role specifically with respect to HPV infection is not known. Present study has been designed to investigate expression and activation of STAT3 in cervical precancer and cancer in relation to HPV infection during cervical carcinogenesis. Established cervical cancer cell lines and prospectively-collected cervical precancer and cancer tissues were analyzed for the HPV positivity and evaluated for STAT3 expression and its phosphorylation by immunoblotting and immunohistochemistry whereas STAT3-specific DNA binding activity was examined by gel-shift assays. RESULTS: Analysis of 120 tissues from cervical precancer and cancer lesions or from normal cervix revealed differentially high levels of constitutively active STAT3 in cervical precancer and cancer lesions, whereas it was absent in normal controls. Similarly, a high level of constitutively active STAT3 expression was observed in HPV-positive cervical cancer cell lines when compared to that of HPV-negative cells. Expression and activity of STAT3 were found to change as a function of severity of cervical lesions from precancer to cancer. Expression of active pSTAT3 was specifically high in cervical precancer and cancer lesions found positive for HPV16. Interestingly, site-specific accumulation of STAT3 was observed in basal and suprabasal layers of HPV16-positive early precancer lesions which is indicative of possible involvement of STAT3 in establishment of HPV infection. In HPV16-positive cases, STAT3 expression and activity were distinctively higher in poorly-differentiated lesions with advanced histopathological grades. CONCLUSION: We demonstrate that in the presence of HPV16, STAT3 is aberrantly-expressed and constitutively-activated in cervical cancer which increases as the lesion progresses thus indicating its potential role in progression of HPV16-mediated cervical carcinogenesis.

SUBMITTER: Shukla S

PROVIDER: S-EPMC2984472 | biostudies-other | 2010

REPOSITORIES: biostudies-other

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Aberrant expression and constitutive activation of STAT3 in cervical carcinogenesis: implications in high-risk human papillomavirus infection.

Shukla Shirish S Shishodia Gauri G Mahata Sutapa S Hedau Suresh S Pandey Arvind A Bhambhani Suresh S Batra Swaraj S Basir Seemi F SF Das Bhudev C BC Bharti Alok C AC

Molecular cancer 20101027

<h4>Background</h4>Recent observations indicate potential role of transcription factor STAT3 in cervical cancer development but its role specifically with respect to HPV infection is not known. Present study has been designed to investigate expression and activation of STAT3 in cervical precancer and cancer in relation to HPV infection during cervical carcinogenesis. Established cervical cancer cell lines and prospectively-collected cervical precancer and cancer tissues were analyzed for the HPV ...[more]

PMID: 20977777

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Project description:BackgroundAberrantly expressed and constitutively active STAT3 signaling plays a pivotal role in initiation and progression of human papillomavirus-induced cervical carcinogenesis. However, the underlying mechanism(s) responsible for pleiotropic effects of STAT3 signaling is poorly understood. In view of emerging regulatory role of microRNAs, Let-7a and miR-21 that may interact with STAT3 signaling and/or its downstream effectors, present study was designed in HPV16-positive cervical cancer cells to assess the functional contribution of these miRs in STAT3 signaling in cervical cancer.MethodsFunctional silencing of STAT3 signaling and HPV16 oncoprotein expression in SiHa cells was done by STAT3-specific and 16 E6 siRNAs. Pharmacological intervention of STAT3 was done using specific inhibitors like curcumin and stattic. Loss-of-function study of miR-21 using miR-21 inhibitor and gain-of-function study of let-7a was done using let-7a mimic in SiHa cells.ResultsFunctional silencing of STAT3 signaling in SiHa cells by STAT3-specific siRNA resulted in a dose-dependent decrease in cellular miR-21 level. Pharmacological intervention of STAT3 using specific inhibitors like curcumin and Stattic that abrogated STAT3 activation resulted in loss of cellular miR-21 pool. Contrary to this, specific targeting of miR-21 using miR-21 inhibitor resulted in an increased level of PTEN, a negative regulator of STAT3, and reduced active pSTAT3 level. Besides miR-21, restoration of cellular Let-7a using chemically synthesized Let-7a mimic reduced overall STAT3 level. Abrogation of HPV oncoprotein E6 by specific siRNA resulted in increased Let-7a but loss of miR-21 and a correspondingly reduced pSTAT3/STAT3 and elevated the level of cellular PTEN.ConclusionsOur results demonstrate existence of a functional loop involving Let-7a, STAT3 and miR-21 which were found potentially regulated by viral oncoprotein E6.ImplicationsmiR-21 and Let-7a along with STAT3 may prove useful targets for pharmacological intervention for management of cervical cancer.

Project description:Few studies have been conducted on the relationship between metabolic syndrome (MetS) and cervical human papillomavirus (HPV) incidence and persistent infection. We performed a prospective cohort study including 8598 female employees in Hunan, China. First, the subjects were stratified into HPV-negative (N = 7282) and HPV-positive (N = 1316) subgroups, according to the results of an HPV DNA test at baseline. Second, comparisons of the risks of HPV incident and persistent infection between MetS-positive (exposed) and MetS-negative (unexposed) groups were conducted among the HPV-negative and -positive subgroups, respectively. There were 976 (11.39%) subjects diagnosed with MetS and 1316 subjects diagnosed with HPV infection at baseline. The 12-month cumulative incidence of any type of HPV and high-risk type HPV were 7.28% (530/7282) and 6.26% (456/7282), respectively. Obesity was a modifier of the association between MetS and HPV incident infection. As long as obesity presented, MetS and hypertriglyceridemia were significantly associated with an increased risk of HPV incident infection (any-type or high-risk type) (adjusted risk ratios (RR) were 2.88 (95% confidence interval (CI): 1.16, 7.19) and 3.29 (95% CI: 1.47, 7.38), respectively). Among those infected with HPV at baseline, the 12-month type-specific persistence rates were 51.67% and 53.38% for any-type and high-risk type HPV, respectively. No interaction was found between obesity and MetS with regard to the risk of HPV persistence. After adjustment for confounding factors, MetS was still associated with increased risk of any-type HPV persistence (RRadj = 1.21, 95% CI: 1.05, 1.41) and high-risk type HPV persistence (RRadj = 1.25, 95% CI: 1.09, 1.46). No single metabolic component was associated with the risk of HPV persistence. The prevalence of MetS was 11.39% among the Hunan female occupational population. MetS was associated with an increased risk of persistent cervical HPV infection and also with an increased risk of HPV incident infection when obesity presented as well.

Project description:ObjectiveTo study the outcome of human papillomavirus (HPV) infection in women with cervical pathology results of non-cervical intraepithelial neoplasia (CIN) or cervical cancer and positive high-risk HPV test, as well as analyze the associated risk factors affecting the outcome of infection.MethodsTo investigate the outcome of high-risk (HR)-HPV infection in the female genital tract and analyze the associated risk factors affecting their outcome, a total of 196 women with positive HR-HPV test results and non-CIN or cervical cancer cervical pathology results were selected for follow-up at the Cervical Disease Clinic of the Obstetrics and Gynecology Hospital, Zhejiang University School of Medicine from January 2017 to March 2020. The follow-up interval was every 6 months, and both cervical cytology (TCT) and HR-HPV testing were performed at each follow-up visit. If the cervical cytology results were normal upon recheck and the HR-HPV test was negative, the woman was considered to be cleared of the HPV infection and was entered into the routine cervical screening population. When the repeat HR-HPV test remained positive after 6 months, the woman was defined as having a persistent HR-HPV infection. If HR-HPV persisted but the TCT results were normal, follow-up was continued. If HR-HPV persisted and the TCT results were abnormal, a colposcopy-guided biopsy was performed immediately. In this situation, if the histological results were still non-CIN or cervical cancer, the follow-up was continued. If the histological results confirmed the development of CIN or invasive cancer, then enter another study follow-up to further track its development and outcome, and the woman commenced the treatment process. The HPV infection clearance time was analyzed by the Kaplan-Meier method, and the comparison of the HPV clearance rate and infection clearance time between each of the different groups was performed using aχ2 test or Fisher's exact test, as appropriate. After the univariate analysis, several significant factors were included in the Cox model and independent risk factors were analyzed.ResultsA total of 163 women were enrolled in this study. The median age was 40.0 years (22-67 years) and the median follow-up time was 11.5 months (6-31 months). The spontaneous clearance rate of HR-HPV infection was 51.5%, and the median time to viral clearance was 14.5 months. Age and the initial viral load were high risk factors affecting the spontaneous clearance of HR-HPV infection. The factors significantly associated with HPV clearance rate and time to HPV clearance consisted of menopause and full-term delivery (P < 0.05).ConclusionsIn women with normal or low-grade lesions on the cell smear, the spontaneous clearance rate of HR-HPV infection was 51.5% and the time to clearance was 14.5 months. Age and the initial viral load were independent associated factors affecting the spontaneous clearance of HR-HPV infection in the female genital tract. These findings suggest that non-young women or those with high viral loads have a higher rate of persistent HR-HPV infection. Thus, intensive screening should be recommended.

Dataset Information

Aberrant expression and constitutive activation of STAT3 in cervical carcinogenesis: implications in high-risk human papillomavirus infection.

Publications

Aberrant expression and constitutive activation of STAT3 in cervical carcinogenesis: implications in high-risk human papillomavirus infection.

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