Indiana University-Purdue University Indianapolis (IUPUI) / Phosphatases of regenerating liver, consisting of PRL-1, PRL-2 and PRL-3, belong to a novel protein tyrosine phosphatases subfamily, whose overexpression promotes cell proliferation, migration and invasion and contributes to tumorigenesis and metastasis. However, although great efforts have been made to uncover the biological function of PRLs, limited knowledge is available on the underlying mechanism of PRLs’ actions, therapeutic value by targeting PRLs, as well as the physiological function of PRLs in vivo. To answer these questions, we first screened a phage display library and identified p115 RhoGAP as a novel PRL-1 binding partner. Mechanistically, we demonstrated that PRL-1 activates RhoA and ERK1/2 by decreasing the association between active RhoA with GAP domain of p115 RhoGAP, and displacing MEKK1 from the SH3 domain of p115 RhoGAP, respectively, leading to enhanced cell proliferation and migration. Secondly, structure-based virtual screening was employed to discover small molecule inhibitors blocking PRL-1 trimer formation which has been suggested to play an important role for PRL-1 mediated oncogenesis. We identified Cmpd-43 as a novel PRL-1 trimer disruptor. Structural study demonstrated the binding mode of PRL-1 with the trimer disruptor. Most importantly, cellular data revealed that Cmpd-43 inhibited PRL-1 induced cell proliferation and migration in breast cancer cell line MDA-MB-231 and lung cancer cell line H1299. Finally, in order to investigate the physiological function of PRLs, we generated mouse knockout models for Prl-1, Prl-2 and Prl-3. Although mice deficient for Prl-1 and Prl-3 were normally developed, Prl-2-null mice displayed growth retardation, impaired male reproductive ability and insufficient hematopoiesis. To further investigate the in vivo function of Prl-1, we generated Prl-1-/-/Prl-2+/- and Prl-1+/-/Prl-2-/- mice. Similar to Prl-2 deficient male mice, Prl-1-/-/Prl-2+/- males also have impaired spermatogenesis and reproductivity. More strikingly, Prl-1+/-/Prl-2-/- mice are completely infertile, suggesting that, in addition to PRL-2, PRL-1 also plays an important role in maintaining normal testis function. In summary, these studies demonstrated for the first time that PRL-1 activates ERK1/2 and RhoA through the novel interaction with p115 RhoGAP, targeting PRL-1 trimer interface is a novel anti-cancer therapeutic treatment and both PRL-1 and PRL-2 contribute to spermatogenesis and male mice reproductivity.

A neoplasia endócrina múltipla tipo 2 (NEM-2) é uma síndrome tumoral herdada por mutações germinativas no proto-oncogene RET (RET) e transmitida por herança autossômica dominante. Atualmente, a indicação de tireoidectomia total preventiva é recomendada a indivíduos portadores de mutações no RET. Analisamos a aplicação do método Eletroforese em Gel Sensível à Conformação (CSGE) no rastreamento de mutações hot-spots do RET. Sete famílias com NEM-2 foram rastreadas pelo CSGE, seqüenciamento gênico e análise do Polimorfismo Conformacional de Cadeia Simples (SSCP). Usando o CSGE e SSCP, identificamos cinco das seis (83,3%) mutações verificadas pelo seqüenciamento: Cys620Arg, Cys634Arg, Cys634Tyr, Val648Ile e Met918Thr. Foram analisados 128 amplicons englobando mutações hot-spots do RET e 116 dentre 128 (90.6%) concordaram com o seqüenciamento genético. Os polimorfismos 691 e 769 também foram documentados pelo CSGE e SSCP. Os dados obtidos por CSGE e SSCP foram totalmente (100%) concordantes. O CSGE revelou ser metodologia sensível, rápida, fácil de ser executada e de baixo custo na detecção de mutações nos códons 620, 634, 648, e 918, as quais constituem grande maioria (~95%) dos pacientes com NEM-2. Quanto à mutação Val804Met (prevalência na população inferior a 3%), o método necessita ser otimizado. Concluímos que o CSGE é uma metodologia efetiva para o rastreamento de mutações que mais freqüentemente ocorrem no RET como causadora de NEM-2. / Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant inherited tumor syndrome caused by activating germline mutations in RET proto-oncogene (RET). Presently, the prophylactic total thyroidectomy is recommended to all RET mutations carriers. Here we tested the Conformation Sensitive Gel Electrophoresis (CSGE) as a screening method for the RET hot-spot mutations. Seven MEN2 families were studied by CSGE, as well as by Single Strand Conformational Polymorphism (SSCP) and direct sequencing analysis. Using CSGE and SSCP, we were able to detect five out of the six (83.3%) RET mutations verified by direct sequencing analysis: Cys620Arg, Cys634Arg, Cys634Tyr, Val648Ile and Met918Thr. RET polymorphisms 691 and 769 were verified by CSGE and SSCP. In our sample, data obtained using CSGE were fully concordant (100%) with SSCP findings. Thus, CSGE showed to be a sensitive, fast, low-cost, and ease procedure to detect RET mutations in codons 620, 634, 648, and 918 which are reported as the most prevalent RET variants (~95%) in large MEN2 series. As to the Val804Met mutation (prevalence in the population lower than 3%), this method still needs to be optimized. We concluded that CSGE is an effective screening method for the most frequent RET hot-spot disease-causing mutations.

A neoplasia endócrina múltipla tipo 2 (NEM-2) é uma síndrome tumoral herdada por mutações germinativas no proto-oncogene RET (RET) e transmitida por herança autossômica dominante. Atualmente, a indicação de tireoidectomia total preventiva é recomendada a indivíduos portadores de mutações no RET. Analisamos a aplicação do método Eletroforese em Gel Sensível à Conformação (CSGE) no rastreamento de mutações hot-spots do RET. Sete famílias com NEM-2 foram rastreadas pelo CSGE, seqüenciamento gênico e análise do Polimorfismo Conformacional de Cadeia Simples (SSCP). Usando o CSGE e SSCP, identificamos cinco das seis (83,3%) mutações verificadas pelo seqüenciamento: Cys620Arg, Cys634Arg, Cys634Tyr, Val648Ile e Met918Thr. Foram analisados 128 amplicons englobando mutações hot-spots do RET e 116 dentre 128 (90.6%) concordaram com o seqüenciamento genético. Os polimorfismos 691 e 769 também foram documentados pelo CSGE e SSCP. Os dados obtidos por CSGE e SSCP foram totalmente (100%) concordantes. O CSGE revelou ser metodologia sensível, rápida, fácil de ser executada e de baixo custo na detecção de mutações nos códons 620, 634, 648, e 918, as quais constituem grande maioria (~95%) dos pacientes com NEM-2. Quanto à mutação Val804Met (prevalência na população inferior a 3%), o método necessita ser otimizado. Concluímos que o CSGE é uma metodologia efetiva para o rastreamento de mutações que mais freqüentemente ocorrem no RET como causadora de NEM-2. / Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant inherited tumor syndrome caused by activating germline mutations in RET proto-oncogene (RET). Presently, the prophylactic total thyroidectomy is recommended to all RET mutations carriers. Here we tested the Conformation Sensitive Gel Electrophoresis (CSGE) as a screening method for the RET hot-spot mutations. Seven MEN2 families were studied by CSGE, as well as by Single Strand Conformational Polymorphism (SSCP) and direct sequencing analysis. Using CSGE and SSCP, we were able to detect five out of the six (83.3%) RET mutations verified by direct sequencing analysis: Cys620Arg, Cys634Arg, Cys634Tyr, Val648Ile and Met918Thr. RET polymorphisms 691 and 769 were verified by CSGE and SSCP. In our sample, data obtained using CSGE were fully concordant (100%) with SSCP findings. Thus, CSGE showed to be a sensitive, fast, low-cost, and ease procedure to detect RET mutations in codons 620, 634, 648, and 918 which are reported as the most prevalent RET variants (~95%) in large MEN2 series. As to the Val804Met mutation (prevalence in the population lower than 3%), this method still needs to be optimized. We concluded that CSGE is an effective screening method for the most frequent RET hot-spot disease-causing mutations.

Indiana University-Purdue University Indianapolis (IUPUI) / Mammary ductal epithelial cell growth is controlled by microenvironmental signals in serum under both normal physiological settings and during breast cancer progression. Importantly, the effects of several of these microenvironmental signals are mediated by the activities of the tumor suppressor protein kinases of the Hippo pathway. Canonically, Hippo protein kinases inhibit cellular growth through the phosphorylation and inactivation of the oncogenic transcriptional co-activator Yes-Associated Protein (YAP). This study defines an alternative mechanism whereby Hippo protein kinases induce growth arrest via the phosphorylation of the long isoform of Angiomotin (Amot130). Specifically, serum starvation is found to activate the Hippo protein kinase, Large Tumor Suppressor (LATS), which phosphorylates the adapter protein Amot130 at serine-175. Importantly, wild-type Amot130 potently inhibits mammary epithelial cell growth, unlike the Amot130 serine-175 to alanine mutant, which cannot be phosphorylated at this residue. The growth-arrested phenotype of Amot130 is likely a result of its mechanistic response to LATS signaling. Specifically, LATS activity promotes the association of Amot130 with the ubiquitin ligase Atrophin-1 Interacting Protein 4 (AIP4). As a consequence, the Amot130-AIP4 complex amplifies LATS tumor suppressive signaling by stabilizing LATS protein steady state levels via preventing AIP4-targeted degradation of LATS. Additionally, AIP4 binding to Amot130 leads to the ubiquitination and stabilization of Amot130. In turn, the Amot130-AIP4 complex signals the ubiquitination and degradation of YAP. This inhibition of YAP activity by Amot130 requires both AIP4 and the ability of Amot130 to be phosphorylated by LATS. Together, these findings significantly modify the current view that the phosphorylation of YAP by Hippo protein kinases is sufficient for YAP inhibition and cellular growth arrest. Based upon these results, the inhibition of cellular growth in the absence of serum more accurately involves the stabilization of Amot130 and LATS, which together inhibit YAP activity and mammary epithelial cell growth.