中文摘要：

为探讨塞来昔布对人结肠癌细胞维甲酸敏感性的作用和环氧化酶2及维甲酸受体beta在其中的作用,本研究应用MTT法和流式细胞仪分别检测细胞的增殖抑制和凋亡率,ELISA检测培养液PGE2的浓度,Westernblotting检测胞核维甲酸受体beta和环氧化酶2的表达。结果显示,塞来昔布可增强ATRA对高表达环氧化酶2的HT-29细胞和低表达环氧化酶2的SW480细胞的增殖抑制作用,增加细胞的凋亡率,提高胞核维甲酸受体beta的表达。此作用不能被外源性PGE2拮抗,也不能被另一种环氧化酶2特异抑制剂NS398复制。因此,塞来昔布可通过非环氧化酶2依赖途径增加结肠癌细胞维甲酸受体beta的表达和细胞对维甲酸的敏感性。此结果有望为临床提供可行的联合用药方案,推广维甲酸的诱导分化和凋亡治疗。

英文摘要：

Retinoid resistance has limited clinical activity of retinoids as differentiation-inducing and apoptosis-inducing drugs. The present study was designed to investigate whether celecoxib （selective COX-2 inhibitor） has effects on cellular retinoid sensitivity of human colon cancer cell lines and its possible mechanism. Cell viability was measured by MTT assay. Apoptosis was detected by Annexin-V/PI staining and flow cytometry assay. PGE2 production was measured by ELISA assay. Expression of RARβ was assayed by Western blotting. The results showed that celecoxib enhanced the inhibitory effect of ATRA in both COX-2 high-expressing HT-29 and COX-2 low-expressing SW480 cell lines. Further study showed the ATRA and celecoxib combination induced greater apoptosis, and the addition of PGE2 did not affect the number of apoptotic cells induced by the combination. Moreover, NS398 （another selective COX-2 inhibitor） did not affect the inhibitory effects of ATRA on both cell lines. Western blotting showed that the expression of RARβ in HT-29 cell lines increased in celecoxib group and combination group. And the addition of PGE2 did not affect the expression of RARβ induced by celecoxib either. In conclusion, celecoxib increased expression of RARβ and cellular ATRA sensitivity through COX-2-independent mechanisms, which may provide a potential strategy for combination therapy.