Mukhopadhyay Partha, Ali M Aktar, Nandi Animesh, Carreon Peter, Choy Hak, Saha Debabrata
Department of Radiation Oncology, Division of Molecular Radiation Biology, University of Texas Southwestern Medical Center, 2201 Inwood Road, Dallas, TX 75390, USA.
Cancer Res. 2006 Feb 1;66(3):1758-66. doi: 10.1158/0008-5472.CAN-05-3317.
Overexpression of cyclooxygenase-2 (COX-2) is frequently observed in several human cancers, including lung, colon, and head and neck. Malignancies are also associated with the dysregulation of cell cycle events and concomitant elevated activity of cyclin-dependent kinases (CDK). CDK2 is a key cell cycle regulatory protein that controls the transition of cells from G(1) to S phase. In this study, we furnish several lines of evidence that show a functional role for the CDK2 in interleukin-1beta (IL-1beta)-induced COX-2 expression in H358 human non-small cell lung carcinoma cell line by blocking CDK2 activity. First, we show that BMS-387032, a potent CDK2 inhibitor, blocks IL-1beta-induced expression as well as steady-state mRNA levels of COX-2. Second, we show that small interfering RNA that abrogates CDK2 expression also blocks IL-1beta-induced COX-2 expression. Third, results from in vitro kinase assays clearly show that IL-1beta induces CDK2 activity in H358 cells and this activity is significantly inhibited by BMS-387032. Moreover, CDK2 inhibition blocks IL-1beta-induced binding to the NF-IL6 element of the COX-2 promoter and inhibits transcription of the COX-2 gene. We also observed that BMS-387032 does not inhibit endogenous expression of COX-2 or prostaglandin synthesis in lung carcinoma cells. Finally, we provide evidence showing that IL-1beta-induced signaling events, such as p38 mitogen-activated protein kinase, phosphorylated stress-activated protein kinase/c-Jun NH(2)-terminal kinase, phosphorylated AKT, and phosphorylated extracellular signal-regulated kinase 1/2, are not inhibited by CDK2 inhibitor. Taken together, the data suggest that CDK2 activity may play an important event in the IL-1beta-induced COX-2 expression and prostaglandin E(2) synthesis and might represent a novel target for BMS-387032.
环氧化酶-2(COX-2)的过表达在包括肺癌、结肠癌和头颈癌在内的多种人类癌症中经常可见。恶性肿瘤还与细胞周期事件的失调以及细胞周期蛋白依赖性激酶(CDK)活性的升高有关。CDK2是一种关键的细胞周期调节蛋白,可控制细胞从G(1)期到S期的转变。在本研究中,我们提供了几条证据,表明通过阻断CDK2活性,CDK2在白细胞介素-1β(IL-1β)诱导的H358人非小细胞肺癌细胞系中COX-2表达中发挥功能性作用。首先,我们表明强效CDK2抑制剂BMS-387032可阻断IL-1β诱导的COX-2表达以及COX-2的稳态mRNA水平。其次,我们表明消除CDK2表达的小干扰RNA也可阻断IL-1β诱导的COX-2表达。第三,体外激酶分析结果清楚地表明,IL-1β可诱导H358细胞中的CDK2活性,而BMS-387032可显著抑制该活性。此外,CDK2抑制可阻断IL-1β诱导的与COX-2启动子的NF-IL6元件的结合,并抑制COX-2基因的转录。我们还观察到BMS-387032不抑制肺癌细胞中COX-2的内源性表达或前列腺素合成。最后,我们提供的证据表明,IL-1β诱导的信号转导事件,如p38丝裂原活化蛋白激酶、磷酸化应激激活蛋白激酶/c-Jun氨基末端激酶、磷酸化AKT和磷酸化细胞外信号调节激酶1/2,不受CDK2抑制剂的抑制。综上所述,数据表明CDK2活性可能在IL-1β诱导的COX-2表达和前列腺素E(2)合成中起重要作用,并且可能代表BMS-387032的一个新靶点。