Knockdown of serine/threonine protein phosphatase 5 enhances gemcitabine sensitivity by promoting apoptosis in pancreatic cancer cells in vitro

MiR-520a-5p/PPP5C regulation pattern is identified as the key to gemcitabine resistance in pancreatic cancer

Objective

To explore the effects of the expression level of miR-520-5p/PPP5C in pancreatic cancer cells and exosomes on cell viability, angiogenesis, autophagy, which involved in the mechanism of gemcitabine resistance in pancreatic cancer.

Methods

APSC-1 cell line was treated with gemcitabine, after which its exosomes were extracted for NTA assay. Subsequently, the drug resistance of APSC-1 cells was assayed using CCK8, as well as the activity of HUVEC cells treated with exosomes from each group of APSC-1 cells after drug resistance treatment as well as overexpression treatment. Five groups of HUVEC cells treated with exosomes were subjected to in vitro tubule formation assay. levels of PPP5C in each group of ASPC-1 cells and their exosomes, levels of overexpressed PPP5C, and related exosomal proteins were examined by WB. mRNA expression levels of PPP5C and levels of miR-520a were examined by qPCR The relationship between miR-520a-5p and PPP5C was investigated. After that, the autophagy of PPP5C was detected. Finally, it was analyzed by TCGA database for survival prognosis analysis.

Results

APSC-1 cells had an IC50 value of 227.1 μM for gemcitabine, elevated PPP5C expression, drug resistance, and enhanced HUVEC cell activity; exosomes CD9, CD63, and CD81 were significantly expressed in all groups; meanwhile, enhanced PPP5C expression not only promoted in vitro tubule formation but also increased autophagy levels; meanwhile, its relationship with miR-520-5p and There was a targeted inhibitory relationship between its level and miR-520-5p and PPP5C, and its elevated level also led to a decrease in the survival level of patients over 3-5 years.

Conclusion

PPP5C has a prognostic role in pancreatic cancer by promoting the value-added and invasion of pancreatic cancer cells, and a targeted inhibitory relationship between miR-520-5p and PPP5C was found.

MicroRNA-365b-3p represses the proliferation and promotes the apoptosis of non-small cell lung cancer cells by targeting PPP5C

MicroRNA (miR)-365b-3p has been recently reported to induce cell cycle arrest and apoptosis in retinoblastoma; however, its expression pattern and biological function in non-small cell lung cancer (NSCLC) remain unknown. The present study aimed to investigate the functional role of miR-365b-3p in NSCLC. The results demonstrated that miR-365b-3p expression level was significantly decreased in NSCLC tissues and cell lines compared with controls using reverse transcriptase quantitative PCR. Furthermore, miR-365b-3p expression level was overexpressed by miR-365b-3p mimics transfection in A549 cells, whereas it was downregulated following H1299 cell transfection with miR-365b-3p inhibitor. Restoration of miR-365b-3p inhibited cell proliferation, induced cell cycle G0/G1 arrest and stimulated apoptosis in A549 cells using CCK-8 assay, colony formation and flow cytometry assay. However, miR-365b-3p inhibitor had the opposite effects in H1299 cells. Furthermore, results from bioinformatics analysis and luciferase reporter assay confirmed that serine/threonine protein phosphatase 5 (PPP5C) was a direct target of miR-365b-3p. In addition, online Kaplan-Meier plotter software demonstrated that high PPP5C expression level was associated with lower overall survival and disease-free survival in patients with NSCLC. Furthermore, PPP5C knockdown imitated the effects of miR-365b-3p mimics on A549 cell proliferation, cell cycle distribution and apoptosis, whereas its overexpression rescued the effects of miR-365b-3p mimics on A549 cell proliferation, cell cycle distribution and apoptosis. In conclusion, the findings from the present study suggested that miR-365b-3p may partly suppress NSCLC cell behaviors by targeting PPP5C, which may represent a promising therapeutic target for patients with NSCLC.

The role of phosphoprotein phosphatases catalytic subunit genes in pancreatic cancer

Compelling evidence suggests that phosphoprotein phosphatases (PPPs) are involved in a large spectrum of physiological and pathological processes, but little is known about their roles in pancreatic cancer. We investigated the expression level, prognostic value, and potential function of PPPs with data from Oncomine, GEPIA, THPA, and TCGA databases and an independent cohort of patients with pancreatic cancer. Among all the PPP catalytic subunits (PPPcs), the transcription levels of PPP1CA, PPP1CB, PPP3CA, PPP3CB, and PPP4C were higher in pancreatic cancer than in normal pancreas (P<0.01, fold change > 2). Kaplan–Meier analysis showed that high transcription levels of PPP1CA, PPP1CB, PPP2CA, PPP2CB, PPP3CA, and PPP4C correlated with poorer survival. In contrast, patients with high levels of PPP3CB, PPP3CC, PPP5C, PPP6C, and PPEF2 had much better prognoses. Data from THPA and patients with pancreatic cancer enrolled in our hospital also confirmed the prognostic value of PPP1CA, PPP1CB, PPP2CA, PPP2CB, PPP3CA, PPP3CB, and PPP6C at the protein level. In addition, the Pearson Chi-square test showed that PPP3CB level was significantly correlated with T and N stages. GO and KEGG analyses showed that the genes and pathways related to the pathogenesis and progression of pancreatic cancer were greatly affected by alterations in PPPcs. Results of the present study suggest that PPP1CA, PPP1CB, PPP2CA, PPP2CB, and PPP3CA have deleterious effects but PPP3CB, PPP5C, and PPP6C have beneficial effects on pancreatic cancer.