| Abstract: | 肺癌大約佔總癌症死亡人數的百分之二十。而台灣的女性及男性癌症更高居第一及第二位。已知抽菸是主要導致肺癌的重要致病因子，但非抽菸肺癌患者的致病原因卻大多不清楚，尤其是台灣女性肺癌患者百分之九十以上為非抽菸者。本實驗室先前研究已發現，人類乳突瘤病毒 (HPV) 16與18型的感染，與不抽菸台灣女性肺癌的形成有關，並會促使IL-6蛋白大量的表現。本研究試圖尋找在人類乳突瘤病毒感染後，下游是否有其他cytokines參與人類乳突病毒感染之肺癌的發生。
文獻指出osteopontin (OPN) 是一個cytokine，也是一種分泌型的磷酸蛋白，在發炎反應與組織修復過程中扮演著重要的角色。又知OPN表現量，在人類腫瘤組織中有顯著的增高的現象，其中包括肺癌，因此推測OPN過量表現，可能參與肺腫瘤之轉移，所以OPN過量表現，可做為肺癌之預後指標。本研究利用免疫組織化學染色法分析，肺腫瘤組織中OPN蛋白之表現，是否與HPV 16或18型感染有關 ﹖本研究共分析了113個非小細胞肺癌患者，陽性率約為48％，並發現OPN的表現與HPV 16或18型的感染有顯著的相關性 (HPV 16：p = 0.034；HPV 18：p = 0.002)，在轉染HPV 16/18致癌蛋白E5、E6或E7至肺腺癌細胞株A549的實驗中，發現HPV 16或18型的感染，的確會促使OPN蛋白表現量增加。在肺腫瘤組織的免疫組織化學染色之實驗發現，OPN與IL-6的表現在統計上有顯著的相關性 (p = 0.01)。已知NF-κB在病毒或細菌之感染時，會被活化大量表現，因此同樣以免疫組織化學染色分析NF-κB的次單元-- p65蛋白在HPV 16或18型感染的肺腫瘤中之表現，結果發現p65蛋白表現與HPV 16型的感染有顯著的相關性 (p = 0.002)，但與HPV 18無關。在轉染HPV致癌蛋白的實驗中發現，HPV16 E5會促使p65蛋白的表現量增加。另外也發現p65蛋白的表現與OPN (p < 0.001) 及IL-6 (p = 0.011) 蛋白表現之間有顯著的相關性。
綜合以上的結果推測，人類乳突瘤病毒可能經由NF-κB (p65) 誘發OPN及IL-6的生成而參與肺腫瘤的形成。
The deaths of lung cancer probably accounts for 20% of all cancers. Lung cancer is the leading and second cause of cancer death in Taiwanese women and men, respectively. It is well known that cigarette smoking is the major factor of lung cancer. However, aetiological factor(s) of non-smoking lung cancer was still unclear. There are more than 50% of Taiwanese lung cancer can not be explained by cigarette smoking and more than 90% of female lung cancer patients were nonsmokers. Our previous reports indicated that a higher prevalence of HPV 16/18 infections was found in non-smoking female tumors compared with those male cases, and suggesting that HPV 16/18 infections was associated with Taiwanese female lung cancer development. Additionally, IL-6 expression in lung tumors was correlated with HPV 16/18 infections. In the present study, we hypothesized that osteopontin(OPN), a cytokine might play a role in HPV associated lung tumorigenesis. One hundred and thirteen of lung tumors were surgically resected from non-small cell lung cancer (NSCLC) patients and immunohistochemisty (IHC) was used to evaluate OPN protein expression in lung tumors in this study. Fifty-four of 113 (48%) tumors had OPN immunostaining positive. Interestingly, OPN expression in lung tumors was significantly associated with HPV 16 or 18 infection (HPV16: P = 0.034; HPV 18: p = 0.002). Moreover, IHC data showed that OPN protein expression was significantly correlated with IL-6 expression (P = 0.01). When HPV 16 E5, E6, E7 and HPV 18 E6 and E7 were respectively transfected into lung adenocarcinoma A549 cells, OPN protein expression levels evaluated by western blot were significantly up-regulated by the oncoproteins of HPV 16 or 18 compared with that of parental A549 cells and vector. We further speculated that frequent OPN and IL-6 expressions in HPV-infected lung tumors may be mediated through NF-kB signaling pathway. A subunit of NF-kB, p65 protein expression in lung tumors was further evaluated by IHC. Our data indicated that p65 immunostainings were significantly associated with OPN and IL-6 expressions, respectively (P < 0.001 for OPN; P = 0.011 for IL-6), and moreover, p65 expression was correlated with HPV 16 infection (p=0.002), but not observed in HPV 18. The transfection experiment data showed that the increase of p65 protein expression was only observed in A549 cells with HPV 16 E5, not in other transfected A549 cells.
In conclusion, the involvement of HPV 16/18 infection in lung tumorigenesis may be, at least in part, mediated through NF-kB pathway to up-regulate OPN and IL-6 overexpressions both have been shown to involve in lung tumor metastasis. |
