Browsing by Subject "PTEN"

Now showing 1 - 3 of 3
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    BRN2 is a non-canonical melanoma tumor-suppressor
    (Springer Nature, 2021-06-17) Hamm, Michael; Sohier, Pierre; Petit, Valérie; Raymond, Jérémy H.; Delmas, Véronique; Le Coz, Madeleine; Gesbert, Franck; Kenny, Colin; Aktary, Zackie; Pouteaux, Marie; Rambow, Florian; Sarasin, Alain; Charoenchon, Nisamanee; Bellacosa, Alfonso; Mosteo, Laura; Lauss, Martin; Meijer, Dies; Steingrimsson, Eirikur; Jönsson, Göran B.; Cornell, Robert; Davidson, Irwin; Goding, Colin R.; Larue, Lionel; Sánchez del Campo Ferrer, Luis; Bioquímica y Biología Molecular A
    While the major drivers of melanoma initiation, including activation of NRAS/BRAF and loss of PTEN or CDKN2A, have been identified, the role of key transcription factors that impose altered transcriptional states in response to deregulated signaling is not well understood. The POU domain transcription factor BRN2 is a key regulator of melanoma invasion, yet its role in melanoma initiation remains unknown. Here, in a BrafV600E PtenF/+ context, we show that BRN2 haplo-insufficiency promotes melanoma initiation and metastasis. However, metastatic colonization is less efficient in the absence of Brn2. Mechanistically, BRN2 directly induces PTEN expression and in consequence represses PI3K signaling. Moreover, MITF, a BRN2 target, represses PTEN transcription. Collectively, our results suggest that on a PTEN heterozygous background somatic deletion of one BRN2 allele and temporal regulation of the other allele elicits melanoma initiation and progression
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    Evidence for different expression profiles for c-Met, EGFR, PTEN and the mTOR pathway in low and high grade endometrial carcinomas in a cohort of consecutive women. Occurrence of PIK3CA and K-Ras mutations and microsatellite instability
    (F. Hernández y Juan F. Madrid. Universidad de Murcia: Departamento de Biología Celular e Histología, 2014) Thoury, Anne; Descatoire, Véronique; Kotelevets, Larissa; Kannengiesser, Caroline; Bertrand, Guylène; Theou-Anton, Nathalie; Frey, Caroline; Genestie, Catherine; Raymond, Eric; Chastre, Eric; Lehy, Thérèse; Walker, Francine
    Molecular and genetic investigations in endometrial carcinogenesis may have prognostic and therapeutic implications. We studied the expression of EGFR, c-Met, PTEN and the mTOR signalling pathway (phospho-AKT/phospho-mTOR/phospho-RPS6) in 69 consecutive tumours and 16 tissue microarrays. We also analysed PIK3CA, K-Ras mutations and microsatellite instability (MSI). We distinguished two groups: group 1 (grade 1 and 2 endometrioid cancers) and group 2 (grade 3 endometrioid and type II clear and serous cell cancers). We hypothesised that these histological groups might have different features. We found that a) survival was higher in group 1 with less aggressive tumours (P<0.03); b) EGFR (P=0.01), PTEN and the AKT/mTOR/RPS6 signalling pathway were increased in group 1 versus group 2 (P=0.05 for phospho-mTOR); c) conversely, cMet was higher (P<0.03) in group 2 than in group 1; d) In group 1, EGFR was correlated with c-Met, phosphomTOR, phospho-RPS6 and the global activity of the phospho-AKT/phospho-mTOR/phospho-RPS6 pathway. In group 2, EGFR was correlated only with the phosphoAKT/phospho-mTOR/phospho-RPS6 pathway, whereas c-Met was correlated with PTEN; e) survival was higher for tumours with more than 50% PTEN-positive cells; f) K-RAS and PIK3CA mutations occurred in 10-12% of the available tumours and MSI in 40.4%, with a loss of MLH1 and PMS2 expression. Our results for endometrial cancers provide the first evidence for a difference in status between groups 1 and 2. The patients may benefit from different targeted treatments, antiEGFR agents and rapamycin derivatives (anti-mTOR) for group 1 and an anti c-MET/ligand complex for group 2.
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    LncRNA AY343892 inhibits breast cancer development by positively regulating BRCA1-mediated transcription of PTEN
    (Universidad de Murcia, Departamento de Biologia Celular e Histiologia, 2020) Li, Yan; Zhang, Miao; Li, Fan
    reast cancer remains a major challenge despite dramatic advances in cancer research. The long non-coding RNA (lncRNA) has been reported to associate with carcinogenesis and progression of various cancers. In this research, we found that lncRNA AY343892 was significantly down-regulated in breast cancer tissues and cells. Besides, breast cancer patients with high AY343892 level exhibited a favorable prognosis. Functional assays indicated that overexpression of AY343892 significantly inhibited proliferation and promoted apoptosis in breast cancer cells. In terms of mechanism, PTEN and BRCA1 were confirmed to be regulated by AY343892 in breast cancer. Luciferase activity and chromatin immunoprecipitation (ChIP) assays indicated that AY343892 can regulate the promoter of PTEN by binding to BCRA1. Further investigation suggested that knockdown of AY343892 significantly promoted MDA-MB-231 cell proliferation and inhibited MDA-MB-231 cell apoptosis. However, these effects were reversed when PTEN was up- regulated. Moreover, PTEN silence can also countervail the inhibitory effect of overexpressed BCRA1 or AY343892 on the expressions of genes related to proliferation and apoptosis in breast cancer. In conclusion, this study illustrated that AY343892 inhibited breast cancer development by positively regulating BRCA1-mediated transcription of PTEN. This finding contributes to a better understanding in the pathogenesis of breast cancer and provides a theoretical basis for the treatment of breast cancer patients