RESUMEN
Epithelial integrity is maintained by the cytoskeleton and through cell adhesion. However, it is not yet known how a deregulated cytoskeleton is associated with cancer. We identified cancer-related regulator of actin dynamics (CRAD) as frequently mutated or transcriptionally downregulated in colorectal cancer. We found that CRAD stabilizes the cadherin-catenin-actin complex via capping protein inhibition. The loss of CRAD inhibits F-actin polymerization and subsequently disrupts the cadherin-catenin-actin complex, which leads to ß-catenin release and Wnt signalling hyperactivation. In mice, CRAD knockout induces epithelial cell integrity loss and Wnt signalling activation, resulting in the development of intestinal mucinous adenoma. With APC mutation, CRAD knockout initiates and accelerates mucinous and invasive adenoma development in the colorectum. These results define CRAD as a tumour suppressor, the inactivation of which deregulates the cytoskeleton and hyperactivates Wnt signalling thus initiating mucinous colorectal cancer. Our study reveals the unexpected roles of an actin cytoskeletal regulator in maintaining epithelial cell integrity and suppressing tumorigenesis.
Asunto(s)
Adenocarcinoma Mucinoso/genética , Oxidorreductasas de Alcohol/genética , Neoplasias Colorrectales/genética , Citoesqueleto/metabolismo , Regulación Neoplásica de la Expresión Génica , Proteínas de Microfilamentos/genética , beta Catenina/metabolismo , Adenocarcinoma Mucinoso/metabolismo , Adenocarcinoma Mucinoso/patología , Adenoma/genética , Adenoma/metabolismo , Adenoma/patología , Oxidorreductasas de Alcohol/metabolismo , Animales , Línea Celular Tumoral , Neoplasias Colorrectales/metabolismo , Neoplasias Colorrectales/patología , Células HCT116 , Células HEK293 , Células HT29 , Humanos , Ratones Endogámicos BALB C , Ratones Noqueados , Ratones Desnudos , Proteínas de Microfilamentos/metabolismo , Unión ProteicaRESUMEN
This study addresses the individual and combined effects of HIV-1 and methamphetamine (N-methyl-1-phenylpropan-2-amine, METH) on cardiac dysfunction in a transgenic mouse model of HIV/AIDS. METH is abused epidemically and is frequently associated with acquisition of HIV-1 infection or AIDS. We employed microarrays to identify mRNA differences in cardiac left ventricle (LV) gene expression following METH administration (10d, 3mg/kg/d, subcutaneously) in C57Bl/6 wild-type littermates (WT) and Tat-expressing transgenic (TG) mice. Arrays identified 880 differentially expressed genes (expression fold change>1.5, p<0.05) following METH exposure, Tat expression, or both. Using pathway enrichment analysis, mRNAs encoding polypeptides for calcium signaling and contractility were altered in the LV samples. Correlative DNA methylation analysis revealed significant LV DNA methylation changes following METH exposure and Tat expression. By combining these data sets, 38 gene promoters (27 related to METH, 11 related to Tat) exhibited differences by both methods of analysis. Among those, only the promoter for CACNA1C that encodes L-type calcium channel Cav1.2 displayed DNA methylation changes concordant with its gene expression change. Quantitative PCR verified that Cav1.2 LV mRNA abundance doubled following METH. Correlative immunoblots specific for Cav1.2 revealed a 3.5-fold increase in protein abundance in METH LVs. Data implicate Cav1.2 in calcium dysregulation and hypercontractility in the murine LV exposed to METH. They suggest a pathogenetic role for METH exposure to promote LV dysfunction that outweighs Tat-induced effects.
