RESUMEN
GATA-6 is a transcription factor that participates in cell lineage differentiation and organogenesis in many tissue types. The abnormal expression of GATA-6 is associated with the development of diverse cancers. GATA-6 acts as an oncogene or tumor suppressor based on tumor origin. Here, we investigated the effects of GATA-6 on lung squamous cell carcinoma (LSCC). We found that GATA-6 was significantly reduced in LSCC tissues compared with the paired normal tissues. The overexpression of GATA-6 inhibited LSCC cell proliferation and migration. Importantly, a luciferase reporter assay and chromatin immunoprecipitation assay demonstrated that GATA-6 negatively regulated the expression of sonic hedgehog (Shh) by directly binding to its promoter region. Furthermore, N-Shh stimulation rescued the inhibition of LSCC cell proliferation and migration upon GATA-6 overexpression. Thus, GATA-6 inhibited the proliferation and migration of LSCC cells by transcriptionally inhibiting the expression of Shh, indicating that targeting GATA-6 may be a potential approach for LSCC therapy.
Asunto(s)
Carcinoma de Células Escamosas/patología , Movimiento Celular , Factor de Transcripción GATA6/metabolismo , Proteínas Hedgehog/genética , Neoplasias Pulmonares/patología , Transcripción Genética , Proliferación Celular , Regulación Neoplásica de la Expresión Génica , Células HEK293 , HumanosRESUMEN
BACKGROUND: The Hedgehog (Hh) signaling pathway plays critical roles in modulating embryogenesis and maintaining tissue homeostasis, with glioma-associated oncogene (GLI) transcription factors being the main mediators. Aberrant activation of this pathway is associated with various human malignancies including glioblastoma, although the mechanistic details are not well understood. METHODS: We performed a microarray analysis of genes that are differentially expressed in glioblastoma U87 cells overexpressing GLI2A, the active form of GLI2, relative to the control cells. Chromatin immunoprecipitation and dual-luciferase assays were used to determine whether Rho guanine nucleotide exchange factor 16 (ARHGEF16) is a downstream target of GLI2. Then, transwell migration, EdU and soft-agar colony formation assays were employed to test effects of ARHGEF16 on glioma cancer cell migration and proliferation, and the effects of GLI2/ARHGEF16 signaling on tumor growth were examined in vivo. Finally, we performed yeast two-hybrid assay, Co-IP and GST-pull down to identify factors that mediate effects of ARHGEF16. RESULTS: We found that ARHGEF16 mRNA level was upregulated in U87 cells overexpressing GLI2A relative to control cells. GLI2 binds to the ARHGEF16 promoter and activates gene transcription. Glioma cells U87 and U118 overexpressing ARHGEF16 showed enhanced migration and proliferation relative to the control cells, while knockdown of ARHGEF16 in H4 cells led to decreased cell proliferation compared to the control H4 cells. In contrast to the promoting effect of GLI2A overexpression on glioma xenograft growth, both GLI2 inhibition and ARHGEF16 knockdown retarded tumor growth. Cytoskeleton-associated protein 5 (CKAP5) was identified as an interaction protein of ARHGEF16, which is important for the stimulatory effects of ARHGEF16 on glioma cell migration and proliferation. CONCLUSIONS: These results suggest that therapeutic strategies targeting the GLI2/ARHGEF16/CKAP5 signaling axis could inhibit glioma progression and recurrence.
Asunto(s)
Glioma/genética , Factores de Intercambio de Guanina Nucleótido/genética , Proteínas Nucleares/genética , Proteína Gli2 con Dedos de Zinc/genética , Animales , Línea Celular Tumoral , Movimiento Celular/genética , Proliferación Celular/genética , Femenino , Regulación Neoplásica de la Expresión Génica , Glioma/metabolismo , Glioma/patología , Factores de Intercambio de Guanina Nucleótido/biosíntesis , Células HEK293 , Xenoinjertos , Humanos , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Proteínas Asociadas a Microtúbulos/genética , Proteínas Asociadas a Microtúbulos/metabolismo , Proteínas Nucleares/antagonistas & inhibidores , Proteínas Nucleares/metabolismo , ARN Mensajero/genética , ARN Mensajero/metabolismo , Distribución Aleatoria , Transducción de Señal , Activación Transcripcional , Transfección , Regulación hacia Arriba , Proteína Gli2 con Dedos de Zinc/antagonistas & inhibidores , Proteína Gli2 con Dedos de Zinc/metabolismoRESUMEN
Inhibitors of the Hedgehog (Hh) pathway transducer Smoothened (Smo) have been approved for cancer treatment, but Smo mutations often lead to tumor resistance and it remains unclear how Smo is regulated. In this study, we identified the small GTPase Arl13b as a novel partner and regulator of Smo. Arl13b regulated Smo stability, trafficking, and localization, which are each crucial for Hh signaling. In gastric cancer cells, Arl13b stimulated proliferation, migration, and invasion in vitro and in vivo In clinical specimens of gastric cancer, Arl13b expression correlated strongly with tumor size and depth of invasion; patients with high levels of Arl13b had a poor prognosis. Our results show how Arl13b participates in Hh pathway activation in gastric cancer. Cancer Res; 77(15); 4000-13. ©2017 AACR.