Screening Of Plasma Protein Markers In Small Cell Lung Cancer And Their Potential Clinical Value

Objective:Small-cell lung cancer accounts for 20% of incidence rate of lung malignancy,small-cell lung cancer has the characteristics of shorter doubling time,poor cell differentiation,strong invasion and easy metastasis.Therefore,most of the patients with small-cell lung cancer at diagnosis are in extensive stage,with extremely poor prognosis and survival rate in 5 years is extremely low.Valuable biomarkers are needed for accurate diagnosis and prognosis of small-cell lung cancer.In this study,GSH-CAA-X00 protein chip was used to screen the differential proteins in the plasma of patients with small-cell lung cancer before and after treatment as well as the plasma of normal people and the plasma of patients with small-cell lung cancer before and after first-line chemotherapy in order to find the potential biological function of small-cell lung cancer in the occurrence and development of the target protein.As a clinical sample,plasma has the advantages of easy collection,simple operation and low risk.In addition,the protein chip used in this study has the advantages of high throughput,wide variety of overlay proteins,high specificity,good stability and high reliability compared with the traditional method of protein screening.These advantages ensure the smooth progress of this subject.Methods:1.Collection of clinical samples: Four patients with small-cell lung cancer diagnosed by pathology from August 2017 to December 2017 were selected and received two cycles of first-line treatment.Plasma samples were collected once before and after chemotherapy.Plasma samples were collected from 4 healthy subjects and stored in-80 ℃ refrigerator.2.The collected plasma was detected by A protein chip which could recognize 1000 proteins at the same time.The principle was double antibody sandwich method,and the fluorescence signal was finally scanned and collected.3.Analysis of data: After normalized treatment,the levels of plasma were compared in 3 groups: patients with SCLC before chemotherapy and healthy people;patients with SCLC before and after chemotherapy,patients with SCLC after chemotherapy and healthy people.1)Principal component analysis(PCA)was used to analyze the specificity among samples in each group.The method used was prcomp function from R.2)Screening of differential proteins under the following conditions: the difference ratio is less than or equal to 0.83 or more than or equal to 1.2;the fluorescence signal is more than 150,P < 0.05.The results can be visualized by the volcano map.Draw with ggplot function,and the data packet is also ggfortify from R.3)Clustering analysis was carried out between two groups of samples for total 3 groups.The method is heatmap.2 function,and the data packet is gplots from R / bioconductor.4)Through GO enrichment analysis and KEGG pathway enrichment analysis,the important function of differential protein was found,and the gene corresponding to this function was found as well.The method adopted here is Fisher accurate verification and the packet is clusterProfiler from R / P bioconductor.5)The dispersion condition of each differential protein data among three groups was analyzed with box diagram,and GraphPad Prism5 was used to draw the picture.Results:1.The plasma of patients with small cell-lung cancer before chemotherapy and plasma of healthy people group were in accordance with screening conditions and statistically significant differences in protein PDGF-AB、S100A8、GHR、GP73、HTRA2、proGRP、GRO and I-TAC.2.The differential protein MMP-3、NSE、LRIG3、proGRP、GRO and I-TAC in patients with small cell-lung cancer before and after treatment were in accordance with the screening conditions and statistically significant.3.The plasma of patients with small cell-lung cancer after chemotherapy and plasma of healthy people group were in accordance with screening conditions and statistically significant differences in protein Cystatin C、Thrombospondin-5、HTRA2.Conclusion:1.The plasma of patients with small cell-lung cancer before chemotherapy and plasma of healthy people group were in accordance with screening conditions and statistically significant differences in protein PDGF-AB、S100A8、GHR、GP73、HTRA2、proGRP、GRO and I-TAC.2.The differential protein MMP-3、NSE、LRIG3、proGRP、GRO and I-TAC in patients with small cell-lung cancer before and after treatment were in accordance with the screening conditions and statistically significant.3.The plasma of patients with small cell-lung cancer after chemotherapy and plasma of healthy people group were in accordance with screening conditions and statistically significant differences in protein Cystatin C、Thrombospondin-5、HTRA2.4.Combined with the trend and statistical analysis of these differential proteins in the three groups,it was inferred that PDGF-AB、S100A8、HTRA2、GRO、I-TAC,which opens up a new field for future research.It is speculated that PDGF-AB、S100A8、HTRA2、GRO、I-TAC play a role in promoting tumor progression during the occurrence and development of SCLC,which needs to be verified by subsequent studies on cell animals and clinical trials.5.It is proved that ProGRP can be used as a tumor marker of SCLC,and the results、ideas and experimental methods in this subject are reliable and have potential clinical application value.