Mechanism Of Stanniocalcin-1 Regulating Gemcitabine Acquired Resistance In Pancreatic Ductal Adenocarcinoma

BackgroundPancreatic cancer is a highly malignant digestive tumor,with a five-year survival rate of less than 10%,ranking 8th in the number of new cancer cases and 6th in death in China(National Cancer Center data).In recent years,new therapies such as immunotherapy and targeted therapy have achieved good clinical results in many tumors,but they have little effect in pancreatic cancer,and surgery and chemotherapy are still the main treatment methods for pancreatic cancer.At present,gemcitabine is still a first-line chemotherapy drug,however,pancreatic cancer is prone to gemcitabine chemotherapy resistance during treatment,resulting in limited value for improving patient outcomes.The mechanism of gemcitabine resistance is very complex,and there is still no effective treatment to overcome chemotherapy resistance.Therefore,exploring the mechanism of chemoresistance of gemcitabine is a frontier key topic in the basic and clinical research of pancreatic cancer,and has important clinical significance.Our research group constructed more than 100 patient-derived tumor xenograft(PDTX)models of pancreatic cancer in the early stage,and screened out chemotherapy-sensitive and drug-resistant PDTX models through gemcitabine pharmacodynamic experiments.Multiomics high-throughput sequencing of these PDTX models found that stanniocalcin-1 is located at a key node in the pancreatic cancer drug resistance regulatory network.Stanniocalcin-1 is a widely expressed glycoprotein hormone involved in a variety of physiopathological processes;In recent years,it has been found to be involved in the occurrence and development of a variety of cancers,but its function and mechanism in pancreatic cancer have not been specifically reported.This project will further investigate the expression and function of STC1 in PDAC,and the specific mechanism by which stanniocalcin-1 leads to gemcitabine resistance in pancreatic cancer.ObjectiveOn the basis of previous work,this study aims to explore the biological function,regulatory mechanism and clinical significance of STC1 in pancreatic cancer.We designed and performed experiments from the following levels:molecules,animal models and clinical tissue samples:1)To explore the effects of STC1 on malignant phenotypes of pancreatic cancer and the sensitivity of gemcitabine chemotherapy.2)To clarify the molecular mechanism of gemcitabine induced STC1 elevation.3)To clarify the molecular mechanism and dowmstream signaling pathways of chemotherapy resisatcne induced by STC1 in pancreatic cancer cells.4)To clarify the expression level of STC1 in pancreatic cancer tissues,analyze its clinical correlation and relationship with prognosis of patients undergoing gemcitabine chemotherapy.Methods1)RT-qPCR and Western Blot were used to evaluate differential mRNA and protein expression levels.Phenotypic expriments such as proliferation,drug resistance,and migration experiments were used to determine the biological fuctions of STC1 in vitro.Subcutaneous tumorgenesis experiments in nude mice were performed to verify the effect of STC1 on tumorigenesis and tumor growth in vivo.2)Bioinformatics analyses were accomplished using online databases such as GEPIA,cBioPortial,STRING,etc.Afterwards,transcriptome sequencing and Western Blot were performed to determine and validate the downstream signaling pathways of STC1.3)Using TCGA,GEO and other public databases for gene expression analysis and prognostic analysis,utilizing immunohistochemical staining for PD AC clinical specimens,and collecting clinical data for further prognostic analysis.4)Using GraphPad Prism,SPSS and other software for data processing and visualization.ResultsThis study elucidated the expression,function,regulation of chemotherapy resistance ofSTC1 in pancreatic cancer and its clinical significance.1)The expression of STC1:STC1 has higher RNA levels and protein levels in pancreatic cancer cells than normal pancreatic epithelial cells.The expression level of STC1 in tumor tissues is higher than that in paracancerous tissues.STC1 is highly expressed in gemcitabine-resistant PDAC cells and PDTX models.2)Biological functions of STC1:In vitro phenotypic experiments confirmed that STC1 can promote the proliferation,drug resistance,migration and other malignant phenotypes of pancreatic cancer cells.At the same time,in vivo experiments have shown that knocking down STC1 could slow tumor growth and reduce tumor volume.3)Action mechanism of STC1:Mechanistic studies have shown that gemcitabine induces STC1 expression increase by upregulating HIF-1α protein.Going deeper,STC1 can act as a secretory protein to regulate the expression of the downstream target VEGFR1 and activate the downstream PI3K/AKT signaling pathway,enabling pancreatic cancer cells to develop acquired drug resistance.4)Clinical significance of STC1:Clinical correlation and survival analysis indicated that STC1 expression was associated with the prognosis of postoperative patients receiving gemcitabine treatment.Elevated STC1 expression was an independent risk factor for poor prognosis in gemcitabine-treated patients.ConclusionIt was found that the expression level of STC1 was elevated in PD AC cells and tumor tissues.In vitro,STC1 could promote the proliferation,drug resistance and other malignant phenotypes of pancreatic cancer cells.In vivo,STC1 could promote tumor formation and growth.The HIF-1α/STC1/VEGFR1/PI3K-AKT axis was involved in the progression of PD AC and acquired drug resistance.In addition,STC1 is of great significance for the prognosis and treatment of gemcitabine treated PDAC patients,STC1 may be used as a prognostic factor and potential therapeutic target for PDAC chemotherapy.