RESUMEN
Cathepsin L (CTSL), a lysosomal acid cysteine protease, is found to play a critical role in chemosencitivity and tumor progression. However, the potential roles and molecular mechanisms of CTSL in chemoresistance in neuroblastoma (NB) are still unclear. In this study, the correlation between clinical characteristics, survival and CTSL expression were assessed in Versteeg dataset. The chemoresistant to cisplatin or doxorubicin was detected using CCK-8 assay. Western blot was employed to detect the expression of CTSL, multi-drug resistance proteins, autophagy-related proteins and apoptosis-related proteins in NB cells while knocking down CTSL. Lysosome staining was analyzed to access the expression levels of lysosomes in NB cells. The expression of apoptosis markers was analyzed with immunofluorescence. Various datasets were analyzed to find the potential protein related to CTSL. In addition, a subcutaneous tumor xenografts model in M-NSG mice was used to assess tumor response to CTSL inhibition in vivo. Based on the validation dataset (Versteeg), we confirmed that CTSL served as a prognostic marker for poor clinical outcome in NB patients. We further found that the expression level of CTSL was higher in SK-N-BE (2) cells than in IMR-32 cells. Knocking down CTSL reversed the chemoresistance in SK-N-BE (2) cells. Furthermore, combination of CTSL inhibition and chemotherapy potently blocked tumor growth in vivo. Mechanistically, CTSL promoted chemoresistance in NB cells by up-regulating multi-drug resistance protein ABCB1 and ABCG2, inhibiting the autophagy level and cell apoptpsis. Furthermore, we observed six datasets and found that Serglycin (SRGN) expression was positively associated with CTSL expresssion. CTSL could mediate chemoresistance by up-regulating SRGN expression in NB cells and SRGN expression was positively correlated with poor prognosis of NB patients. Taken together, our findings indicate that the CTSL promotes chemoresistance to cisplatin and doxorubicin by up-regulating the expression of multi-drug resistance proteins and inhibiting the autophagy level and cell apoptosis in NB cells. Thus, CTSL may be a therapeutic target for overcoming chemoresistant to cisplatin and doxorubicin in NB patients.
RESUMEN
Autism spectrum disorder (ASD) is a widespread, complex and serious neurodevelopmental disorder. Complex genetic and environmental factors are thought to contribute to the development of ASD. Genome-wide association analysis has identified multiple autism-related genes. Mutation of the phosphatase and tensin homolog (Pten) is closely related to autism and accounts for 5-17% of cases of autism. However, the detailed mechanism is still unclear. Recently, mitochondrial dysfunction was tightly associated with ASD pathogenesis, such as developmental degeneration, learning and various behavioral disorders. The mitochondrial DNA (mtDNA) copy number in children with autism is also significantly increased. The correlation between Pten and mitochondrial dysfunction in autism is still unknown. In this study, we examined how Pten regulates mitochondrial biogenesis through the AKT/GSK-3ß/PGC-1α signaling pathways. We found that PTEN could dephosphorylate AKT to inhibit its activity, leading to decreased GSK3ß phosphorylation. This decrease in GSK3ß phosphorylation, which could activate itself, increased PGC-1α phosphorylation to promote its degradation and then regulated mitochondrial biogenesis by NRF-1 and TFAM downstream of PGC-1α. In the Valproic acid (VPA) induced autism mouse model, the PTEN protein level was significantly decreased while PGC-1α and COX IV levels were increased in the hippocampus and cortex. Our data suggest that there is a correlation between PTEN and mitochondrial dysfunction and this correlation may be a potential mechanism of ASD.