RESUMO
Neural invasion underlies the local spread of gastric cancer and is associated with poor prognosis. This process has been receiving increasing attention in recent years. However, the relationship between neural invasion and the malignant phenotypes of gastric cancer cells, as well as the molecular mechanism involved in this process, remain unclear. In this study, bioinformatics analysis was performed using a dataset obtained from The Cancer Genome Atlas-Stomach Adenocarcinoma. The results revealed that high expression of GDNF family receptor alpha 3 (GFRA3) was associated with a poor prognosis of patients with gastric cancer. GFRA3 is a receptor for artemin (ARTN), a glial cell line-derived neurotrophic factor (GDNF). This association was indicated by short overall/disease-free survival, as well as the presence of high-stage and high-grade disease. Gene set enrichment analysis showed that two cancer-associated pathways, namely KRAS signaling and epithelial-mesenchymal transition (EMT), were activated when GFRA3 was highly expressed in gastric cancer. Further studies confirmed that GFRA3 activated KRAS downstream signaling phosphatidylinositol 3 kinase/protein kinase B (PI3K/AKT) or extracellular signal-regulated kinase (ERK) and induced EMT markers, as well as promoted the migration and invasion of gastric cancer cells. As a ligand of GFRA3, ARTN induced the EMT, migration, and invasion of gastric cancer cells via GFRA3. Notably, the effects of the ARTN-GFRA3 axis were attenuated by treatment with a KRAS inhibitor. The present findings indicated that, during the neural invasion of gastric cancer, ARTN-mediated activation of GFRA3 induces EMT phenotypes, migration, and invasion of gastric cancer cells via KRAS signaling.
Assuntos
Transição Epitelial-Mesenquimal , Receptores de Fator Neurotrófico Derivado de Linhagem de Célula Glial , Invasividade Neoplásica , Transdução de Sinais , Neoplasias Gástricas , Humanos , Linhagem Celular Tumoral , Movimento Celular , Regulação Neoplásica da Expressão Gênica , Receptores de Fator Neurotrófico Derivado de Linhagem de Célula Glial/metabolismo , Receptores de Fator Neurotrófico Derivado de Linhagem de Célula Glial/genética , Proteínas do Tecido Nervoso/metabolismo , Proteínas do Tecido Nervoso/genética , Fenótipo , Fosfatidilinositol 3-Quinases/metabolismo , Prognóstico , Proteínas Proto-Oncogênicas p21(ras)/genética , Proteínas Proto-Oncogênicas p21(ras)/metabolismo , Neoplasias Gástricas/patologia , Neoplasias Gástricas/metabolismo , Neoplasias Gástricas/genéticaRESUMO
We recently reported that growth/differentiation factor 15 (GDF15) and its receptor GDNF family receptor alpha-like (GFRAL) are expressed in the periventricular germinal epithelium thereby regulating apical progenitor proliferation. However, the mechanisms are unknown. We now found GFRAL in primary cilia and altered cilia morphology upon GDF15 ablation. Mutant progenitors also displayed increased histone deacetylase 6 (Hdac6) and ciliary adenylate cyclase 3 (Adcy3) transcript levels. Consistently, microtubule acetylation, endogenous sonic hedgehog (SHH) activation and ciliary ADCY3 were all affected in this group. Application of exogenous GDF15 or pharmacological antagonists of either HDAC6 or ADCY3 similarly normalized ciliary morphology, proliferation and SHH signalling. Notably, Gdf15 ablation affected Hdac6 expression and cilia length only in the mutant periventricular niche, in concomitance with ciliary localization of GFRAL. In contrast, in the hippocampus, where GFRAL was not expressed in the cilium, progenitors displayed altered Adcy3 expression and SHH signalling, but Hdac6 expression, cilia morphology and ciliary ADCY3 levels remained unchanged. Thus, ciliary signalling underlies the effect of GDF15 on primary cilia elongation and proliferation in apical progenitors.
Assuntos
Adenilil Ciclases , Proliferação de Células , Cílios , Proteínas Hedgehog , Desacetilase 6 de Histona , Transdução de Sinais , Animais , Camundongos , Acetilação , Adenilil Ciclases/metabolismo , Adenilil Ciclases/genética , Proliferação de Células/genética , Cílios/metabolismo , Receptores de Fator Neurotrófico Derivado de Linhagem de Célula Glial/metabolismo , Receptores de Fator Neurotrófico Derivado de Linhagem de Célula Glial/genética , Proteínas Hedgehog/metabolismo , Proteínas Hedgehog/genética , Desacetilase 6 de Histona/metabolismo , Desacetilase 6 de Histona/genética , Camundongos Knockout , Células-Tronco/metabolismo , Células-Tronco/citologiaRESUMO
Glioblastoma is the most common primary brain tumor in adults, characterized by an inherent aggressivity and resistance to treatment leading to poor prognoses. While some resistance mechanisms have been elucidated, a deeper understanding of these mechanisms is needed to increase therapeutic efficacy. In this study we first discovered glial-cell derived neurotrophic factor (GDNF) to be upregulated in patient-derived glioblastoma spheroid cultures after chemotherapeutic temozolomide treatment, through RNA-Seq experiments. Therefore, we investigated the role of the GDNF/GDNF receptor alpha 1 (GFRA1) signaling pathway as a resistance mechanism to chemotherapy with temozolomide and lomustine, as well as irradiation using patient-derived glioblastoma spheroid cultures. With qPCR experiments we showed a consistent upregulation of GDNF and its primary receptor GFRA1 following all three lines of treatment. Moreover, CRISPR/Cas9 knock-outs of GDNF in two patient-derived models sensitized these cells to chemotherapy treatment, but not radiotherapy. The increased sensitivity was completely reversed by the addition of exogeneous GDNF, confirming the key role of this factor in chemoresistance. Finally, a CRISPR KO of GFRA1 demonstrated a similar increased sensitivity to temozolomide and lomustine treatment, as well as radiotherapy. Together, our findings support the role of the GDNF/GFRA1 signaling pathway in glioblastoma chemo and radioresistance.