Breast cancer remains the most prevalent cause of cancer mortality in woman worldwide due to the metastatic process and therapy resistance. Resistance against cancer therapy is partially attributed to cancer stem cells (CSCs). These cells arise from epithelial cells undergoing epithelial-to-mesenchymal transition (EMT) and might be responsible for tumor recurrence. In this study, we reported the relevance of miR-155 upregulation in chemoresistant cells associated with EMT. Notably, we found miR-155 induction in exosomes isolated from CSCs and resistant cells, followed by resistant cells’ exosome transfer to the recipient sensitive cells. Functionally, miR-155 mimic assay showed an enrichment in miR-155 from exosome concomitant with miR-155 exosome transfer to breast cancer cells. In parallel to these effects, we also observed EMT change in miR-155 transfected cells. The chemoresistance phenotype transfer to sensitive cells and the migration capability was analyzed by MTT and scratch assays and our results suggest that exosomes may intermediate resistance and migration capacity to sensitive cells partly through exosome transfer of miR-155. Taken together, our findings establish the significance of exosome-mediate miR-155 chemoresistance in breast cancer cells, with implications for targeting miR-155 signaling as a possible therapeutic strategy.
The LAMS study failed to reproduce the performance figures obtained with VIA and VILI (as stand-alone tests) in some other settings, where the prevalence of cervical disease was higher. However, a combined use of VIA or VILI with the Pap test or HCII allowed specific detection of cervical abnormalities.
OBJECTIVE:To assess the prevalence of high-risk genital human papillomavirus (HPV) infection by age group and risk factors associated.
METHODS:Cross-sectional study in a sample of 2,300 women (15-65 years old) who self-referred to cervical cancer screening in Sao Paulo and Campinas, Southeastern Brazil, between February 2002 and March 2003. An epidemiological questionnaire was applied and cervical specimens were obtained for cytology and hybrid capture II test (HCII) for HPV detection. Statistical analysis included Pearson Chi-square and unconditional multiple logistic regression model (forward likelihood ratio).
RESULTS:High-risk genital HPV infection prevalence in this sample was 17.8% and age distribution was as follows: 27.1% (<25 years), 21.3% (25-34 years), 12.1% (35-44 years), 12.0% (45-54 years) and 13.9% (55-65 years). Subjects with the highest number of lifetime sexual partners had the highest rates of genital HPV infection. To be living with a partner, aged 35 to 44 years, and former smokers were protective factors. High-risk genital HPV infection was 14.3% in normal cytology, 77.8% in high grade squamous intraepithelial lesions and in the two cases (100%) of cervical cancer.
CONCLUSIONS:High-risk HPV prevalence was high in the sample studied. The highest prevalence of HPV infection was seen in women under 25 years old and then a new increase was seen over the age of 55 and the highest rates were found among those with many sexual partners during their lifetime.
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