Browsing by Author "Ampuero, Sandra"

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    Merkel cell polyomavirus in non-small cell lung carcinomas from Chile
    (ACADEMIC PRESS INC ELSEVIER SCIENCE, 2012) Gheit, Tarik; Pablo Munoz, Juan; Levican, Jorge; Gonzalez, Carolina; Ampuero, Sandra; Parra, Barbara; Gaggero, Aldo; Corvalan, Alejandro H.; Meneses, Manuel; Tommasino, Massimo; Aguayo, Francisco
    Lung cancer is a leading pathology strongly associated with the smoking habit. However, a viral etiology for a subset of patients developing lung cancer has been suggested. Polyomaviruses (PyVs) are small double stranded DNA viruses associated with the development of some human diseases. However, a causal role of these viruses in human cancer has been difficult to demonstrate. In this study, eighty-six non-small cell lung carcinomas (NSCLCs), including adenocarcinomas (AdCs) and squamous cell lung carcinomas (SQCs) from Chile were analyzed for the presence of PyVs using polymerase chain reaction (PCR). All of the specimens were positive for a fragment of the betaglobin gene. We found that 4/86 (4.7%) of lung carcinomas were positive for PyVs. After sequencing and BlastN alignment, all four cases were identified as Merkel cell polyomaviruses (MCV) that corresponded to two AdCs and two SQCs. A non-significant statistical association was found between the presence of MCV and clinic-pathological features of the patients and tumors. In addition, 1/4 (25%) of the carcinomas were actively expressing large T antigen (LT) transcripts, as demonstrated by reverse-transcriptase PCR (RT-PCR). Thus a possible role of MCV in a very small subset of patients with lung cancer cannot be ruled out and warrants more investigation. (C) 2012 Elsevier Inc. All rights reserved.
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    The prolactin inhibition of follicle-stimulating hormone-induced aromatase activity in cultured rat granulosa cells is in part tyrosine kinase and protein kinase-C dependent
    (1996) Alberto Villanueva, Luis; Mendez, Isabel; Ampuero, Sandra; Larrea, Fernando
    The inhibitory actions of prolactin on gonadal steroidogenesis have been reported in different species and under a variety of experimental approaches. In this study, the mechanisms of the in-vitro effects of human prolactin (hPRL) on human follicle stimulating hormone (hFSH)-induced aromatase activity were determined using cultured granulosa cells from diethylstilboestrol (DES)-primed immature rats. Human PRL caused a dose-dependent decrease in hFSH-induced 17 beta-oestradiol production, even when cells were cultured in the presence of a cAMP analogue (8-Br-cAMP). These effects of hPRL appeared to be specific, since addition of an anti-rat PRL receptor monoclonal antibody (mAb) mimicked the hPRL inhibitory effect upon steroidogenesis in rat granulosa cells. In order to assess the importance of tyrosine kinase and protein kinase-C activation in the hPRL inhibitory effects upon oestrogen biosynthesis, cells were cultured in the presence of kinase inhibitors. The results showed that addition of genistein or staurosporine (a tyrosine kinase and protein kinase-C antagonist respectively) to cultured granulosa cells resulted in potent inhibition of hPRL actions upon hFSH-induced aromatization in a dose-dependent manner. These observations suggest that tyrosine kinase and protein kinase-C activation are involved in the biochemical events leading to hPRL inhibitory effects at the gonadal level.