RESUMO
Activating mutations in KRAS are among the most frequent events in diverse human carcinomas and are particularly prominent in human pancreatic ductal adenocarcinoma (PDAC). An inducible Kras(G12D)-driven mouse model of PDAC has established a critical role for sustained Kras(G12D) expression in tumor maintenance, providing a model to determine the potential for and the underlying mechanisms of Kras(G12D)-independent PDAC recurrence. Here, we show that some tumors undergo spontaneous relapse and are devoid of Kras(G12D) expression and downstream canonical MAPK signaling and instead acquire amplification and overexpression of the transcriptional coactivator Yap1. Functional studies established the role of Yap1 and the transcriptional factor Tead2 in driving Kras(G12D)-independent tumor maintenance. The Yap1/Tead2 complex acts cooperatively with E2F transcription factors to activate a cell cycle and DNA replication program. Our studies, along with corroborating evidence from human PDAC models, portend a novel mechanism of escape from oncogenic Kras addiction in PDAC.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Adenocarcinoma/metabolismo , Carcinoma Ductal Pancreático/metabolismo , Neoplasias Pancreáticas/metabolismo , Fosfoproteínas/metabolismo , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Adenocarcinoma/patologia , Animais , Carcinoma Ductal Pancreático/patologia , Ciclo Celular , Proteínas de Ciclo Celular , Linhagem Celular Tumoral , Replicação do DNA , Proteínas de Ligação a DNA/metabolismo , Modelos Animais de Doenças , Fatores de Transcrição E2F/metabolismo , Humanos , Camundongos , Neoplasias Pancreáticas/patologia , Proteínas Proto-Oncogênicas/metabolismo , Fatores de Transcrição de Domínio TEA , Fatores de Transcrição/metabolismo , Proteínas de Sinalização YAP , Proteínas ras/metabolismoRESUMO
Galectin-3-binding protein (gal3bp) and its receptor/ligand, galectin-3 (gal3), are secreted proteins that initiate signaling cascades in several diseases, and recent human proteomic data suggest they may play a role in venous thrombosis (VT). We hypothesized that gal3bp and gal3 may promote VT. Using a mouse stasis model of VT, we found that gal3bp and gal3 were localized on vein wall, red blood cells, platelets, and microparticles, whereas leukocytes expressed gal3 only. Gal3 was dramatically increased during early VT and gal3bp:gal3 colocalized in the leukocyte/endothelial cell interface, where leukocytes were partially attached to the vein wall. Thrombus size correlated with elevated gal3 and interleukin-6 (IL-6) vein wall levels. Recombinant gal3 promoted VT and increased vein wall IL-6 mRNA. Although recombinant gal3 restored the VT size in gal3(-/-) mice, it had no effect on IL6(-/-) mice, suggesting that gal3:gal3bp promotes VT through IL-6. Moreover, significantly fewer activated neutrophils were present in the gal3(-/-) vein walls. In a group of human patients, elevated circulating gal3bp correlated with acute VT. In conclusion, gal3bp:gal3 play a critical role in VT, likely via IL-6 and PMN-mediated thrombotic mechanisms, and may be a potential biomarker in human VT.
Assuntos
Galectina 3/metabolismo , Glicoproteínas/metabolismo , Trombose Venosa/metabolismo , Animais , Antígenos de Neoplasias/sangue , Biomarcadores/sangue , Biomarcadores Tumorais/sangue , Plaquetas/metabolismo , Proteínas de Transporte/sangue , Movimento Celular , Quimiocina CCL2/metabolismo , Modelos Animais de Doenças , Células Endoteliais/metabolismo , Eritrócitos/metabolismo , Galectina 3/deficiência , Galectina 3/genética , Glicoproteínas/sangue , Humanos , Interleucina-6/deficiência , Interleucina-6/genética , Interleucina-6/metabolismo , Leucócitos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , Proteínas Recombinantes/sangue , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Trombose Venosa/sangue , Trombose Venosa/etiologiaRESUMO
Keratins that are overexpressed selectively in human carcinomas may offer diagnostic and prognostic utility. In this study, we show that high expression of keratin-17 (K17) predicts poor outcome in patients with cervical cancer, at early or late stages of disease, surpassing in accuracy either tumor staging or loss of p27(KIP1) as a negative prognostic marker in this setting. We investigated the mechanistic basis for the biologic impact of K17 through loss- and gain-of-function experiments in human cervix, breast, and pancreatic cancer cells. Specifically, we determined that K17 functions as an oncoprotein by regulating the subcellular localization and degradation of p27(KIP1). We found that K17 was released from intermediate filaments and translocated into the nucleus via a nuclear localization signal (NLS), specific among keratins, where it bound p27(KIP1) during G1 phase of the cell cycle. p27(KIP1) lacks a nuclear export signal (NES) and requires an adaptor for CRM1 binding for nuclear export. In K17, we defined and validated a leucine-rich NES that mediated CRM1 binding for export. Cervical cancer cells expressing K17 mutations in its NLS or NES signals exhibited an increase in levels of nuclear p27(KIP1), whereas cells expressing wild-type K17 exhibited a depletion in total endogenous p27(KIP1). In clinical specimens of cervical cancer, we confirmed that the expressions of K17 and p27(KIP1) were inversely correlated, both across tumors and within individual tumors. Overall, our findings establish that K17 functions specially among keratins as an oncoprotein by controlling the ability of p27(KIP1) to influence cervical cancer pathogenesis.