RESUMEN
BACKGROUND: Prostate cancer (PCa) is a leading cause of cancer morbidity and mortality in men worldwide; however, PCa incidence and mortality rates vary widely across geographic regions and ethnic groups. The current study was designed to elucidate the pivotal factors involved in PCa occurrence and development. METHODS: We performed RNA sequencing on the prostate tumor and adjacent normal tissues from Chinese PCa patients. Genes identified via genome-wide expression profile analysis were validated by quantitative reverse-transcription polymerase chain reaction and immunohistochemistry. Hypermethylation of CpG islands was assessed by nested methylation-specific PCR. Whole genome microarray analysis was performed using an Affymetrix GeneChip. RESULTS: We identified nine possible abnormally expressed genes (P < .05) and then revealed TWIST2 as having strikingly lower expression in tumors than in control tissues (P < .01). Low messenger RNA expression levels of TWIST2 were associated with hypermethylation of CpG islands in its promoter region. In accordance with these findings, PCa tumor tissues showed markedly decreased TWIST2 protein expression compared to that in both normal and prostatic intraepithelial neoplasia tissues by immunohistochemical staining. Ectopic expression of TWIST2 in LNCap cells not only inhibited cell proliferation and colony formation in vitro and tumor growth in vivo but also induced transcriptional repression of a cell proliferation-related gene cohort, including androgen receptor signaling mediators, cyclins, homeobox genes, forkhead box genes, and SOX2. CONCLUSIONS: Our results suggest that TWIST2 could function as a tumor suppressor involved in the pathogenesis of PCa by influencing the expression of target genes and that hypermethylation of the TWIST2 promoter in prostate tumors may be an underlying mechanism for TWIST2 transcriptional silencing.
Asunto(s)
Neoplasias de la Próstata/genética , Proteínas Supresoras de Tumor , Proteína Relacionada con Twist 2/genética , China , Islas de CpG , Metilación de ADN , Epigénesis Genética , Expresión Génica , Regulación Neoplásica de la Expresión Génica/genética , Estudio de Asociación del Genoma Completo , Humanos , Masculino , Análisis por Micromatrices , Regiones Promotoras Genéticas , Neoplasia Intraepitelial Prostática/química , Neoplasias de la Próstata/química , ARN Mensajero/análisis , Análisis de Secuencia de ARN , Células Tumorales Cultivadas , Proteína Relacionada con Twist 2/análisis , Proteína Relacionada con Twist 2/fisiologíaRESUMEN
Belted cattle have a circular belt of unpigmented hair and skin around their midsection. The belt is inherited as a monogenic autosomal dominant trait. We mapped the causative variant to a 37 kb segment on bovine chromosome 3. Whole genome sequence data of 2 belted and 130 control cattle yielded only one private genetic variant in the critical interval in the two belted animals. The belt-associated variant was a copy number variant (CNV) involving the quadruplication of a 6 kb non-coding sequence located approximately 16 kb upstream of the TWIST2 gene. Increased copy numbers at this CNV were strongly associated with the belt phenotype in a cohort of 333 cases and 1322 controls. We hypothesized that the CNV causes aberrant expression of TWIST2 during neural crest development, which might negatively affect melanoblasts. Functional studies showed that ectopic expression of bovine TWIST2 in neural crest in transgenic zebrafish led to a decrease in melanocyte numbers. Our results thus implicate an unsuspected involvement of TWIST2 in regulating pigmentation and reveal a non-coding CNV underlying a captivating Mendelian character.
Asunto(s)
Región de Flanqueo 5'/genética , Bovinos/genética , Variaciones en el Número de Copia de ADN/genética , Melanocitos/fisiología , Proteína Relacionada con Twist 2/genética , Región de Flanqueo 5'/fisiología , Animales , Animales Modificados Genéticamente/genética , Bovinos/crecimiento & desarrollo , Variaciones en el Número de Copia de ADN/fisiología , Femenino , Masculino , Fenotipo , Reacción en Cadena de la Polimerasa , Pigmentación de la Piel/genética , Proteína Relacionada con Twist 2/fisiología , Pez Cebra/genéticaRESUMEN
Basal-like breast cancer (BLBC) is associated with high-grade, distant metastasis and poor prognosis. Elucidating the determinants of aggressiveness in BLBC may facilitate the development of novel interventions for this challenging disease. In this study, we show that aldo-keto reductase 1 member B1 (AKR1B1) overexpression highly correlates with BLBC and predicts poor prognosis in breast cancer patients. Mechanistically, Twist2 transcriptionally induces AKR1B1 expression, leading to nuclear factor κB (NF-κB) activation. In turn, NF-κB up-regulates Twist2 expression, thereby fulfilling a positive feedback loop that activates the epithelial-mesenchymal transition program and enhances cancer stem cell (CSC)-like properties in BLBC. AKR1B1 expression promotes, whereas AKR1B1 knockdown inhibits, tumorigenicity and metastasis. Importantly, epalrestat, an AKR1B1 inhibitor that has been approved for the treatment of diabetic complications, significantly suppresses CSC properties, tumorigenicity, and metastasis of BLBC cells. Together, our study identifies AKR1B1 as a key modulator of tumor aggressiveness and suggests that pharmacologic inhibition of AKR1B1 has the potential to become a valuable therapeutic strategy for BLBC.
