NSE Enhances Stem Cell-like Characteristics Of Small Cell Lung Cancer Through NBL1 Activating BMP2/SMAD/ID1 Pathway

Lung cancer is an extremely common cancer with the highest mortality rate.Small cell lung cancer(SCLC)is the most malignant tumor type in lung cancer,accounting for about 15% of lung cancers.It has the characteristics of high-malignant tumors such as rapid progress,early metastasis,and recurrence.Currently the treatment of SCLC is mainly chemotherapy and radiotherapy,but it is easy to relapse after treatment.In addition,immunotherapy and targeted therapy have not benefited most patients.Therefore,the survival prognosis of SCLC patients is extremely poor,with a 5-year survival rate of about 7%,and there is an urgent need to explore new and effective treatment strategies.Neuron specific enolase(NSE)is often used in the auxiliary diagnosis,efficacy judgment and prognosis monitoring of SCLC,but the function and mechanism of NSE in SCLC are still unclear.This study aims to clarify the function and mechanism of NSE in SCLC,and provide new and effective ideas and directions for the treatment of SCLC patients.Through flow cytometry,we found that NSE could increase the proportion of ALDHhigh cancer stem cells in SCLC cells.The results of functional experiments such as sphere formation,cell proliferation and drug resistance showed that NSE could promote the formation of spheroidal clones,cell proliferation and drug resistance of SCLC cells.The results of q RT-PCR and Western blot experiments showed that NSE could promote the expression of stemness-related genes SOX2,Nanog,OCT4 in SCLC cells.Subcutaneous transplantation tumor experiments in nude mice found that NSE could promote the growth of SCLC tumors in vivo.Further,through RNA-seq and cell function experiments,we found that NSE could activate the BMP2/ Smad/ ID1 pathway through NBL1,thereby enhancing the stem cell-like characteristics of SCLC cells.Then,through Co-IP,Western blot and other experiments,we found that NSE might down-regulate the expression of NBL1 through glycolytic pathway and interact with NBL1,thereby enhancing the interaction between BMP2 and its receptor BMPR1 A to activate the BMP2/ Smad/ ID1 pathway.Finally,in the tumor tissues of SCLC patients,through immunohistochemical experiments and clinical data analysis,we found that the expression level of NSE was positively correlated with the expression level of ALDH1A1,and negatively correlated with the expression level of NBL1;high levels of NSE,ALDH1A1 and low levels of NBL1 were associated with poor overall survival of SCLC patients.This study clarified the role and molecular mechanism of NSE in enhancing the stem cell-like characteristics of SCLC.NSE may inhibit the expression of NBL1 through the glycolytic pathway and interact with NBL1,thereby weakening the competitive inhibition of BMP2 by NBL1,enhancing the interaction between BMP2 and its receptor BMPR1 A,and then activating the BMP2/ Smad/ ID1 pathway,enhancing the stem cell-like characteristics of SCLC cells,and promoting tumor progression.To sum up,this study provides a new theoretical basis and effective biological targets for the treatment of SCLC,which has important clinical significance.