Investigation for involvement of COX-2 in invasion and metastasis of oral cancer and inhibitory effect by selective COX-2 inhibitors

本研究旨在通过检测COX-2在侵袭前或转移灶的免疫组织化学表达，分析COX-2基因转移对培养口腔癌细胞侵袭转移能力的影响及其分子机制，阐明COX-2在口腔癌侵袭转移过程中的作用。通过检测选择性COX-2抑制剂对侵袭转移的抑制作用，探讨COX-2是否成为口腔癌治疗的分子靶点。所得结果如下：1) COX-2在有淋巴结转移的口腔癌原发灶中的表达明显高于无淋巴结转移的口腔癌原发灶，且在有淋巴结转移的口腔癌原发灶中表达高于无淋巴结转移的口腔癌原发灶。其表达随肿瘤大小的增加而增加，且多见于侵袭性前部。随着COX-2表达的增加，laminin-5 γ 2和DNA-Topo II α也增加。2)淋巴结转移、COX-2高表达和DNA-Topo II α患者总体5年生存率较低。3)高表达COX-2的口腔癌KB细胞克隆（KB/COX）转染COX-2 cDNA后，COX-2蛋白和PGE-2水平升高，细胞运动和侵袭能力较对照组（KB/neo）增强。4)与KB/neo相比，KB/COX中MMP9、pro-MMP2、活化- mmp2、MT1-MMP和趋化因子受体CXCR4的表达增加，TIMP1、TIMP2和E-cadherin的表达降低。5)与KB/neo相比，KB/COX在裸鼠皮下移植中表现出较高的致瘤性和肿瘤生长，在原位移植中表现出积极的局部侵袭性。在KB/COX肿瘤组织中检测到高明胶酶活性。6)心脏内注射或原位移植KB/COX可有效地引起肺多发转移和骨颈部淋巴结转移，而KB/neo则很少引起淋巴结转移。7)COX-2抑制剂塞来昔布和舒林酸通过诱导细胞凋亡，呈剂量依赖性地抑制头颈部癌细胞的生长，并抑制PGE-2的产生和COX-2的表达。塞来昔布增强了抗癌药物对癌细胞的细胞毒性。8) COX-2在dba诱导的仓鼠颊袋癌变过程中表达升高，塞来昔布和舒林酸通过诱导细胞凋亡和抗血管生成，延缓癌变，抑制肿瘤生长，延长寿命。9)丁酸钠或维甲酸诱导人口腔鳞癌SCC25细胞角质化分化，抑制肿瘤生长和COX-2表达。少

This study was designed to elucidate the involvement of COX-2 in invasion and metastasis of oral cancer by examining immunohistochemical expression of COX-2 in invasive front or metastatic lesion and analyzing the effect of COX-2 gene transfer and its molecular mechanism on the abilities of invasion and metastasis in cultured oral carcinoma cells. It was also investigated whether COX-2 becomes a molecular target for treatment of oral cancer by examining the inhibitory effect of selective COX-2 inhibitors on invasion and metastasis. The results obtained were as follows.1)Expression of COX-2 was significantly higher in primary lesions of oral cancer with lymph node (LN) metastasis than in those without LN metastasis, and higher in metastatic lesions than in primary lesions. The expression was increased as tumor size was increased and more in invasive front. As COX-2 expression was increased, laminin-5 γ 2 and DNA-Topo II α were also increased.2)Overall 5-year survival was poor in patient … More s with LN metastasis and high COX-2 expression and DNA-Topo II α.3)Oral carcinoma KB cell clone (KB/COX) with high COX-2 expression transfected with COX-2 cDNA produced elevated COX-2 protein and PGE-2, and showed high potentials of cell motility and invasion as compared to the control (KB/neo).4)KB/COX showed increased expression of MMP9, pro-MMP2, activated-MMP2, MT1-MMP and chemokine receptor CXCR4, and decreased expression of TIMP1, TIMP2 and E-cadherin, as compared to KB/neo.5)KB/COX demonstrated high tumorigenicity and tumor growth in subcutaneous transplantation to nude mice and aggressive local invasion in orthotopic transplantation, as compared to KB/neo. High gelatinase activity was detected in KB/COX tumor tissues.6)Intracardiac injection or orthotopic transplantation of KB/COX resulted in multiple metastasis to lung and bone and neck LN metastasis efficiently, but those of KB/neo caused few.7)COX-2 inhibitor celecoxib and sulindac inhibited the growth of head and neck cancer cell lines in a dose-dependent manner via apoptosis induction, and also inhibited PGE-2 production and COX-2 expression. Celecoxib augmented the cytotoxicity of anticancer drugs to cancer cells.8)Expression of COX-2 was increased toward DMBA-induced hamster cheek pouch carcinogenesis, and administration of celecoxib and sulindac resulted in retardation of cancerization, inhibition of tumor growth and prolonged life span via apoptosis induction and antiangiogenesis.9)Treatment with sodium butyrate or retinoic acid induced differentiation to cell keratinization in human oral squamous carcinoma SCC25 cells and inhibited tumor growth and COX-2 expression. Less