VEGFR-2 Expression In NSCLC And Their Clinical Significance

Study backgroundThe incidence and mortality of lung cancer continue to grow worldwide and have been No.1 among malignant tumors with poor prognosis.Since the early symptoms are not apparent or typical,the majority of patients have lost the chance of operation when the clinical diagnosis is established.Most progresses into stage III-IV.The 5-year survival rate is only 8%-15%.The conventional non-selective radiotherapy and chemotherapy result in great side effects,large-scale injury,multi-drug resistance and other issues.The treatment effect has almost reached the plateau.With the advent of targeted therapy,the “precise medicine” paradigm based on individualized medicine is focused.The application of targeted inhibitors of EGFR or VEFGR,has become a new therapeutic strategy,and has achieved favorable efficacy.VEGFR is widely recognized as the strongest,the most specific regulatory factor of angiogenesis since the VEGF-A/VEGFR-2 signaling pathway,an important pathway of tumor angiogenesis,directly regulates angiogenesis and indirectly promotes the formation of lymphatic metastatic lesions.Thus,VEGFR-2 is considered to be an important anti-angiogenesis target.It can be used to predict the efficacy of targeted drugs,help clinicians to select medication regimens according to gene expression,make treatment decisions and evaluate the efficacy and prognosis.However,the genetic heterogeneity of tumor has a significant influence on its prognosis,recurrence,metastasis and drug resistance,and brings great difficulty to the individualized precise treatment of cancer patients.Currently,the heterogeneity of EGFR in lung cancer is under debate.No study on the heterogeneity of VEGFR in lung cancer has been reported.Therefore,it is of great significance to clarify the existence of VEGFR-2 heterogeneity in lung cancer,for the guidance of the feasibility and clinical value of the selective application of anti-angiogenic drugs according to the expression of VEGFR-2.Objective1.To verify the up-regulation of VEGFR-2 in the tissues of NSCLC and the role in the genesis,development,invasion and metastasis in NSCLC.2.To investigate the intra-tumor heterogeneity and inter-tumor consistency of the expression of VEGFR-2 in lung cancer.4.To investigate the feasibility and clinical value of the selective application of anti-angiogenic drugs according to the expression of VEGFR-2.Subjects1.The tissue samples of the primary lung lesions and the corresponding metastatic lesions in mediastinal lymph nodes were collected from the resected lesions during thoracic surgery in our hospital from January 2012 to January 2014.The patients did not receive preoperative radiotherapy or chemotherapy.The pathological diagnosis of NSCLC was confirmed with HE staining of the paraffin-embedded specimens from 60 cases.All patients did not receive preoperative radiotherapy or chemotherapy.Complete clinical data were available.12 paraffin-embedded specimens of adjacent normal lung tissue(over 4cm from the cancer tissue)at the same period were included in the control group.2.20 specimens of the primary lung lesions(10 cases of squamous cell carcinoma,10 cases of adenocarcinoma)were randomly selected,including 3 cases of squamous cell carcinoma and adenocarcinoma.Each case was divided into 9 regions.A total of 54 samples were collected to detect the difference in VEGFR-2 expression among different regions of the primary tumor.3.Another 40 cases,controlled by the primary lung lesions and the corresponding metastatic lesions in mediastinal lymph nodes,to detect the difference and association in the expression of VEGFR-2.Methods1.The expression of VEGFR-2 in the primary lung tumor tissues(resected in surgery,pathologically confirmed NSCLC)and adjacent normal lung tissues was detected with RT-PCR to verify the up-regulation of VEGFR-2 in lung cancer tissues.2.The expression of VEGFR-2 in different sites of the primary lung tumor tissues was detected to investigate the intra-tumor heterogeneity of VEGFR-2 expression.3.The expression of VEGFR-2 in the metastatic lesions of mediastinal lymph nodes were detected and compared with the tumor tissues in the primary lung cancer and the corresponding metastatic lesions of mediastinal lymph nodes to analyze the difference and association between them and investigate the inter-tumor heterogeneity of VEGFR-2 expression in primary lung cancer and the metastatic lesions of mediastinal lymph nodes.Results1.The expression of VEGFR-2 in primary lung lesions was up regulated when compared with that in the adjacent normal lung tissues.(P=0.023)2.The expression of VEGFR-2 has inhomogeneity in both adenocarcinoma and squamous cell carcinoma.It was higher in adenocarcinoma than in squamous cell carcinoma.(P=0.023)3.The expression of VEGFR-2 in different sites of the primary lung cancerlesions: 124 regions from 20 cases were examined and the results showed different expression profiles(P=0.001).and intra-tumor heterogeneity both in pulmonary adenocarcinoma(P=0.002)and squamous cell carcinoma(P=0.002).4.The expression of VEGFR-2 in the metastatic lesions of mediastinal lymph nodes: 39 from 40 cases were examined.The results showed no difference between the primary lung cancer and the metastatic lesions of mediastinal lymph nodes(P=0.1614).Adenocarcinoma was(P=0.0942);while squamous cell carcinoma was(P=0.6953).The lymph node metastasis of squamous cell carcinoma was positively associated with the primary lung tumor(rs=0.84;P=0.002),while the metastasis of adenocarcinoma was irrelevant(rs=0.19;P=0.312).Conclusion1.The genesis and growth of tumor is dependent on the nourishment of angiogenesis.VEGFR-2 is essential in the angiogenesis of tumors.VEGFR-2,as an important regulator of the signaling pathway of angiogenesis,is expressed in primary lung cancer and the metastatic lesions of lymph nodes.And the expression level was significantly higher than that in adjacent normal lung tissues.VEGFR-2 plays a role throughout the whole process(genesis,development,invasion and metastasis)of lung cancer.2.The expression of VEGFR-2 is heterogenic in different pathological types of lung cancer(such as squamous cell carcinoma and adenocarcinoma).The level of VEGFR-2 expression is higher in adenocarcinoma than that in squamous cell carcinoma,suggesting that anti-angiogenesis drug may be more effective for the treatment of pulmonary adenocarcinoma than squamous cell carcinoma.This is consistent with the approved indications of bevacizumab.3.The expression of VEGFR-2 is heterogenic in the primary lung cancer tissues(that is,intra-tumor heterogeneity).The small biopsy specimens cannot represent the whole tumor,indicating the clinical examination results of VEGFR-2 collected from small biopsy specimens cannot reflect the overall gene expression profile in the primary tumor.The application of anti-angiogenic drugs simply based on the gene expression in biopsy samples may result in bias in treatment decisions.Multiple and multi-site biopsy(even a second biopsy,when necessary)is required in clinical practice.4.The expression of VEGFR-2 is up regulated in the primary and lymph node metastatic lesions of lung cancer.However,there was no difference between the primary tumor and lymph node metastatic lesion.Or there is no inter-tumor heterogeneity.This demonstrates the lymph node metastases of lung cancer also need the nourishment of neogenetic blood vessels.Clinicians can harvest the lymph node specimens for biopsy and the examination results of VEGFR-2 can be used to guide the application of anti-angiogenic drugs.