Samanta Ajoy K, Huang Helen J, Le Xiao-Feng, Mao Weiqun, Lu Karen H, Bast Robert C, Liao Warren S-L
Department of Biochemistry and Molecular Biology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas, USA.
Cancer. 2009 Sep 1;115(17):3897-908. doi: 10.1002/cncr.24445.
Constitutively activated nuclear factor kappa B (NFkappaB) contributes to the development of cancer by regulating the expression of genes involved in cell survival, metastasis, and angiogenesis. The authors have demonstrated that MEKK3 plays a critical role in cytokine-mediated NFkappaB activation, and that stable expression of MEKK3 in cultured cells leads to increased NFkappaB activity.
MEKK3 expression in ovarian cancer cells or tumors was assessed by Western blotting and real-time polymerase chain reaction. NFkappaB activities were analyzed by electrophoretic mobility shift assay and luciferase reporter assays. Western blot analysis for the survival factors were also performed and correlated with MEKK3 and NFkappaB activities. Cell survival assays were used to determine the sensitivity of ovarian cancer cells to various chemotherapeutic agents.
The authors found that 63% of the ovarian cancers had higher MEKK3 expression than the normal ovarian epithelial cells. Ovarian cancers with high MEKK3 showed correspondingly high IkappaB kinase and NFkappaB activity. Moreover, MEKK3 coimmunoprecipitated with Akt and cooperated with Akt to synergistically activate NFkappaB. Consistent with increased MEKK3 and NFkappaB activity in ovarian cancers, Bcl-2, Bcl-xL, survivin, and X-linked inhibitor of apoptosis levels were increased, which correlated with increased resistance to chemotherapeutic agents. Knockdown of MEKK3 with small interfering RNA significantly increased cancer cell sensitivity to paclitaxel.
MEKK3 may be aberrantly expressed in ovarian cancers and plays an important role in tumors with constitutively activated NFkappaB.
持续激活的核因子κB（NFκB）通过调节参与细胞存活、转移和血管生成的基因表达，促进癌症的发展。作者已经证明，MEKK3在细胞因子介导的NFκB激活中起关键作用，并且在培养细胞中稳定表达MEKK3会导致NFκB活性增加。
通过蛋白质免疫印迹法和实时聚合酶链反应评估卵巢癌细胞或肿瘤中MEKK3的表达。通过电泳迁移率变动分析和荧光素酶报告基因分析来分析NFκB活性。还进行了生存因子的蛋白质免疫印迹分析，并将其与MEKK3和NFκB活性相关联。使用细胞存活分析来确定卵巢癌细胞对各种化疗药物的敏感性。
作者发现，63%的卵巢癌中MEKK3的表达高于正常卵巢上皮细胞。MEKK3高表达的卵巢癌相应地显示出较高的IκB激酶和NFκB活性。此外，MEKK3与Akt共免疫沉淀，并与Akt协同激活NFκB。与卵巢癌中MEKK3和NFκB活性增加一致，Bcl-2、Bcl-xL、存活素和X连锁凋亡抑制蛋白水平升高，这与对化疗药物的耐药性增加相关。用小干扰RNA敲低MEKK3可显著增加癌细胞对紫杉醇的敏感性。
MEKK3可能在卵巢癌中异常表达，并在NFκB持续激活的肿瘤中起重要作用。
