| Purpose:Radiotherapy is an important treatment for non-small cell lung cancer.The biggest challenge for lung cancer radiotherapy is the movement of tumor location due to respiratory.The purpose of this study is to explore the strategy of high efficiency,precision and small damage to normal tissues by comparing and analyzing the different methods of drawing the volume target of lung cancer based on three dimensional CT and four dimensional CT.At the molecular level,we explored the interaction mechanism of αvβ6 and IL-8 in lung cancer,in order to provide theoretical basis and molecular targets for clinical treatment of lung cancer.Methods:This article is divided into two parts: clinical internal target volume(ITV)analysis and basic research.The first part: the clinical ITV analysis reviewed 20 non-small cell lung cancer patients in the Radiotherapy Department of Jiangsu Cancer Hospital from September,2017 to February,2018.The ITVs was defined in four different methods based on three dimensional CT and four dimensional CT.The tumor center displacement in the three-dimensional direction and the volume and geometry of each ITV were carried out and compared.The second part: in the basic research experiment we detected the expression of integrin αvβ6 and IL-8 in lung cancer tissue specimens by immunohistochemistry and real-time fluorescent quantitative PCR.MTT and flow cytometry were used to verify the correlation between the expression of integrin αvβ6 and IL-8 in lung cancer,and cell apoptosis,migration and invasion test proved that both of αvβ6 and IL-8 were found in lung cancer.The protein expression of MMP-2,MMP-9,MAPK,ERK,JNK and p38 in lung cancer cells were detected and their correlation was analyzed.A lung-metastatic tumor model was studied to verify the biological function and specific mechanism of integrin αvβ6 in lung cancer cells in mice.Results:The four dimensional CT showed that the displacement of GTV centroid in anterior-posterior(A-P)and superior-inferior(S-I)directions was significantly greater(mean: 0.21 ± 0.3cm and 0.32 ± 0.41 cm,respectively,P < 0.01)in comparison with left-right(L-R)direction(mean value: 0.07 ± 0.07cm).The volume of ITV based on the four dimensional CT maximum density projection(MIP)image reached the best matching index(MI)with ITV10phase(0.95 + 0.02).ITV formed by the two extreme respiratory phases(0% and 50%)of the four dimensional CT(ITV2phase)and by margin created from the 95% displacement of three dimensional CT(ITV3DCT)was compared with the ITV10 phase,with the MI as 0.83± 0.08 and 0.78 ± 0.12,respectively.Human lung cancer samples were analyzed and it revealed that the immunohistochemical and mRNA expression of integrin αvβ6 were significantly correlated with the expression of IL-8.Furthermore,in vitro,integrin avP6 increased cell proliferation,migration and invasion by impairing the expressions of MMP-2and MMP-9 and inhibited cell apoptosis in human lung cancer cell A549 and H460.In addition,integrin αvβ6 upregulated IL-8 expression through activating MAPK/ERK signaling.The in vivo experiment showed that integrin αvβ6 promoted tumor growth in xenograft model mice by accelerating tumor volume and reducing apoptosis.Meanwhile,lung metastasis model experiment suggested that integrinαvβ6 stimulated tumor metastasis with the increase of lung/total weight and tumor nodules.Simultaneously,integrin αvβ6 upregulated IL-8 expression detected by both western blots and immunohistochemistry,along with the activation of MAPK/ERK signaling.Conclusions:Our data suggested that,The ITVMIP may be an efficient approach alternative to optimal ITV10 Phases in radiotherapy for NSCLC.In vitro and in vivo,integrin αvβ6promoted lung cancer proliferation and metastasis,at least in part,through upregulation of IL-8-mediated MAPK/ERK signaling.Thus,the inhibition of integrinαvβ6 and IL-8 might be the key for the treatment of lung cancer. |
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