| At present,the incidence and mortality of lung cancer rank first among malignant tumors,which seriously threaten human life and health.Surgery is one of the best treatments for lung cancer.For patients who have not been diagnosed before surgery and who need to determine the extent of resection during surgery,frozen pathological sections are usually needed to help diagnose,but pathological examination can not diagnose lung cancer quickly and accurately.Accurate differentiation of lung cancer from normal lung tissue is the premise to ensure the therapeutic effect of surgery.Therefore,it is urgent to establish a new real-time and rapid diagnostic method for lung cancer.Mass spectrometry(MS)is a high sensitivity,flexible detection method and fast analysis technology.Internal extraction electrospray ionization mass spectrometry(iEESI-MS)is a new atmospheric ionization mass spectrometry technology developed rapidly in recent years,the technology can directly obtain the internal chemical co mposition of samples without sample pretreatment,.The main contents of this study are internal extraction electrospray ionization mass spectrometry for rapid identification of lung cancer xenografts in nude mice.Objective: To explore the effect and molecular basis of iEESI-MS technology in rapid differentiation between lung cancer transplanted tumors and normal lung tissues in nude mice,and to study the relationship between the difference of phospholipid expression and the mechanism of lung cancer.Method: Without any pretreatment of the tissues,we used self-designed sampler and iEESI-MS technology to analyze 64 xenograft tissues and 64 normal lung tissue rapidly from 16 lung cancer xenograft models in nude mice.The extractant is water/methanol(70:30,v:v)and the velocity of flow is set to 1 uL/min.The mass spectrometer parameters are set to positive ion mode,the mass scanning range is mass-charge ratio(m/z)700-900 Da,the ion transfer tube temperature is 150?,set the ion source voltage as 5 kV,the ncapillary voltage is set to 10 V,and voltage of the lens is 100 V.The system automatically optimizes other mass spectrometry conditions.The principal component analysis(PCA)was used to analyze the fingerprint spectrum data of lung cancer transplantation tumors and normal lung tissues in MATLAB 7.9 software.The relative abundance of different ions was performed by SPSS 21.Result: Within the detection range of m/z 700-900,the main ions of the first-order mass spectrometry fingerprints of transplanted tumor tissues were m/z 782.7,798.7,808.7,824.7,832.7,848.7,etc.while those of normal lung tissues were m/z 756.7,772.7,782.7,798.7,832.7,etc.The relative abundance of m/z 782.7,798.7 and 832.7 in transplanted lung tissue was significantly higher than that in normal lung tissue,while the relative abundance of m/z 756.7 and 772.7 in transplanted lung tissue was lower than that in normal lung tissue.lung cancer transplantation was discriminated accurately from normal lung tissue by PCA.Collision-induced dissociation(CID)experiments of different substances proved m/z 756.7 is dipalmitoylphosphatidylcholine+sodium ion,m/z 772.7 is dipalmitoylphosphatidylcholine + potassium ion,m/z 782.7 is 1-palmitoyl-2-oleoyl lecithin+sodium ion,m/z 798.7 is 1-palmitoyl-2-oleoyl lecithin+ potassium ion.Conclusion: IEESI-MS coupled with PCA can rapidly differentiate lung cancer xenografts from normal lung tissues in nude mice based on the differential expression of phospholipids,which may provide a theoretical basis for rapid intraoperative differentiation of lung cancer tissues,and provide a new idea for the study of the mechanism and molecular markers of lung cancer. |
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