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Cervical cancer is one of the most common malignancies in women. MicroRNAs (miRNAs) are involved in a variety of fundamental cellular processes, including carcinogenesis. The potential utilization of aberrantly expressed miRNAs as novel biomarkers in cervical cancer diagnostics is growing. We investigated miRNA expression profiles during the progression of dysplasia in cervical epithelium to identify aberrantly expressed miRNAs. High-throughput miRNA profiling of high-grade precancerous lesions identified 79 miRNAs showing significant difference in expression values compared to normal cervical epithelium. Ten selected miRNAs were subsequently measured in an independent group of samples to validate them as promising biomarkers of cervical carcinogenesis. MicroRNAs miR-10b-5p, miR-34c-5p, miR-409-3p and miR-411-5p were confirmed as downregulated, while miR-10a-5p, miR-132-3p, miR-141-5p were significantly upregulated in dysplastic cervical tissues. Further investigation revealed an inverse correlation of miR-409-3p with E6 mRNA levels in precancerous cervical lesions. Subsequent in vitro analyses showed a direct involvement of this miRNA in the regulation of E6 oncogene levels, thus confirming a potential tumor suppressor function of miR-409-3p in cervical malignancies. Hence, miR-409-3p may represent a useful early marker and a potential therapeutic target for cervical cancer.

Epithelial-mesenchymal transition (EMT) is a process involved not only in morphogenesis and embryonic development, but also in cancer progression, whereby tumor cells obtain a more aggressive metastatic phenotype. Anterior gradient protein 2 (AGR2) maintains the epithelial phenotype and blocks the induction of EMT, thus playing an undeniable role in tumor progression. However, the mechanism through which AGR2 expression is regulated, not only during EMT, but also in the early stages of cancer development, remains to be elucidated. In the present study, we show an inverse correlation of AGR2 with ZEB1 (zinc finger enhancer binding protein, &delta, EF1) that was verified by analysis of several independent clinical data sets of lung adenocarcinomas. We also identified the ZEB1 binding site within the AGR2 promoter region and confirmed AGR2 as a novel molecular target of ZEB1. The overexpression of ZEB1 decreased the promoter activity of the AGR2 gene, which resulted in reduced AGR2 protein level and the acquisition of a more invasive phenotype of these lung cancer cells. Conversely, silencing of ZEB1 led not only to increased levels of AGR2 protein, but also attenuated the invasiveness of tumor cells. The AGR2 knockout, vice versa, increased ZEB1 expression, indicating that the ZEB1/AGR2 regulatory axis may function in a double negative feedback loop. In conclusion, we revealed for the first time that ZEB1 regulates AGR2 at the transcriptional level, while AGR2 presence contributes to ZEB1 mRNA degradation. Thus, our data identify a new regulatory mechanism between AGR2 and ZEB1, two rivals in the EMT process, tightly associated with the development of metastasis.

Background During cancer progression, epithelial cancer cells can be reprogrammed into mesenchymal-like cells with increased migratory potential through the process of epithelial-mesenchymal transition (EMT), representing an essential step of tumor progression towards metastatic state. AGR2 protein was shown to regulate several cancer-associated processes including cellular proliferation, survival and drug resistance. Methods The expression of AGR2 was analyzed in cancer cell lines exposed to TGF-β alone or to combined treatment with TGF-β and the Erk1/2 inhibitor PD98059 or the TGF-β receptor specific inhibitor SB431542. The impact of AGR2 silencing by specific siRNAs or CRISPR/Cas9 technology on EMT was investigated by western blot analysis, quantitative PCR, immunofluorescence analysis, real-time invasion assay and adhesion assay. Results Induction of EMT was associated with decreased AGR2 along with changes in cellular morphology, actin reorganization, inhibition of E-cadherin and induction of the mesenchymal markers vimentin and N-cadherin in various cancer cell lines. Conversely, induction of AGR2 caused reversion of the mesenchymal phenotype back to the epithelial phenotype and re-acquisition of epithelial markers. Activated Smad and Erk signaling cascades were identified as mutually complementary pathways responsible for TGF-β-mediated inhibition of AGR2. Conclusion Taken together our results highlight a crucial role for AGR2 in maintaining the epithelial phenotype by preventing the activation of key factors involved in the process of EMT. Electronic supplementary material The online version of this article (doi:10.1186/s12885-017-3537-5) contains supplementary material, which is available to authorized users.

Tamoxifen treatment in breast cancer patients is associated with increased risk of endometrial malignancies. Significantly, higher AGR2 expression was found in endometrial cancers that developed in women previously treated with tamoxifen compared to those who had not been exposed to tamoxifen. An association of elevated AGR2 level with myometrial invasion occurrence and invasion depth was also found. In vitro analyses identified a stimulatory effect of AGR2 on cellular proliferation. Although adverse tamoxifen effects on endometrial cells remain elusive, our work identifies elevated AGR2 as a candidate tamoxifen-dependent mechanism of action responsible for increased incidence of endometrial cancer.

Expression of the AGR2 oncogene was shown to be associated with estrogen receptor positive tumors. This gene contributes to enhanced cellular proliferation, drug resistance, metastasis development and may also serve as a predictor of poor prognosis. However, our analysis of AGR2 expression in a subset of estrogen-receptor negative tumors revealed that AGR2 could also be upregulated in hormone-independent manner. AGR2 expression was shown to be significantly increased in HER2 positive breast tumors on both the mRNA and the protein level. Moreover, in a subset of estrogen- and progesterone-receptor negative and simultaneously HER2-positive cases, increased AGR2 expression significantly correlated with worse patient prognosis. Subsequent analysis of independent data sets either collected in our institute or obtained from Oncomine cancer microarray database confirmed all these findings.

International audience; Human anterior gradient proteins AGR2 and AGR3 are overexpressed in a variety of adenocarcinomas and are often secreted in cancer patients' specimens, which suggests a role for AGR proteins in intra and extracellular compartments. Although these proteins exhibit high sequence homology, AGR2 is predominantly described as a pro-oncogene and a potential prognostic biomarker. However, little is known about the function of AGR3. Therefore, the aim of the present study was to investigate the role of AGR3 in breast cancer. The results demonstrated that breast cancer cells secrete AGR3. Furthermore, it was revealed that extracellular AGR3 (eAGR3) regulates tumor cell adhesion and migration. The current study indicated that the pharmacological and genetic perturbation of Src kinase signaling, through treatment with Dasatinib (protein kinase inhibitor) or investigating cells that express a dominant-negative form of Src, significantly abrogated eAGR3-mediated breast cancer cell migration. Therefore, the results indicated that eAGR3 may control tumor cell migration via activation of Src kinases. The results of the present study indicated that eAGR3 may serve as a microenvironmental signaling molecule in tumor-associated processes.

There is growing epidemiological evidence indicating an association between diabetes mellitus and the increased incidence of colorectal cancer (CRC). The preferred initial and most widely used pharmacological agent for the treatment of type 2 diabetes is metformin, which in parallel reduces the risk of CRC and improves patient prognosis. AMP-activated protein kinase (AMPK) appears to be tightly associated with the beneficial metabolic effects of metformin, serving as a cellular energy sensor activated in response to a variety of conditions that deplete cellular energy levels. Such conditions include nutrient starvation (particularly glucose), hypoxia and exposure to toxins that inhibit the mitochondrial respiratory chain complex. The aim of the present study was to determine the effect of metformin on CRC cell lines, with different levels of anterior gradient 2 (AGR2) expression, exposed to 5-fluorouracil (5-FU) and oxaliplatin, alone or in combination with metformin. AGR2 has recently emerged as a factor involved in colon carcinogenesis. In AGR2-knockout cells, markedly higher levels of phosphorylated-AMPK were observed in comparison with control cells transfected with GFP-scrambled guide RNA, which indicated that the presence of AGR2 may interfere with the metformin-dependent activation of AMPK. In addition, metformin in combination with 5-FU and oxaliplatin induced ROS production and attenuated autophagy. This effect was enhanced in AGR2-knockout cells.

Background Cervical cancer is the fourth most common cancer in women and is usually associated with human papillomavirus infection. Viral infections are usually characterized by morphological changes of epithelial cells; however, it is difficult to determine using recently available screening methods whether the changes are caused by productive infection or by malignant disease. Thus, new efforts are required to find novel diagnostic biomarkers of cervical cancer, such as miRNAs, which are small non-coding RNAs involved in the regulation of gene expression. Materials and methods miR-34c levels in cervical cancer cell lines were determined by the droplet-digital polymerase chain reaction. Changes in miR-34c expression in vitro were achieved by transient transfection with a specific miRNA mimic and inhibitor oligonucleotides. Cell proliferation was analyzed by crystal violet staining followed by spectrophotometric measurements. The effect on migratory properties was studied using a „scratch“ assay. Western blotting analysis was used to determine the expression of selected proteins. Results The downregulation of miR-34c expression was associated with a slight increase in cellular proliferation and a significant increase in cell migration. The analysis of miR-34c expression performed on a set of 39 dysplastic tissues and 35 samples of healthy controls subsequently revealed a significant difference (p l 0.01) in the level of this miRNA. Conclusion Comparative expression analysis revealed lower expression of miR-34c in cervical precanceroses than in normal untransformed epithelium. in vitro modulation of miR-34c expression revealed its tumor suppressor role in cervical malignancies. Key words: cervical cancer - HPV - miRNA - HSIL - hsa-miR-34c - precancerosis This work was supported by the projects MEYS - NPS I - LO1413, P206/12/G151 and MH CZ - DRO (MMCI, 00209805). The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers. Accepted: 16. 7. 2018.