Duxbury Mark S, Ito Hiromichi, Zinner Michael J, Ashley Stanley W, Whang Edward E
Department of Surgery, Brigham and Women's Hospital, Harvard Medical School, 75 Francis Street, Boston, MA 02115, USA.
Oncogene. 2004 Jan 15;23(2):465-73. doi: 10.1038/sj.onc.1207036.
Anoikis is the apoptotic response induced in normal cells by inadequate or inappropriate adhesion to substrate. It is postulated that resistance to anoikis facilitates tumorigenesis and metastasis. Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is an immunoglobulin superfamily member overexpressed in a number of human cancers and implicated in anoikis resistance. We tested the effect of CEACAM6 gene silencing on anoikis in pancreatic adenocarcinoma cell lines. Anoikis was induced in PANC1, Capan2, MiaPaCa2 and Mia(AR) (a MiaPaCa2-derived anoikis-resistant subline) by culture in poly-2-hydroxyethylmethacrylate-coated wells. Anoikis was quantified by YO-PRO-1/propidium iodide staining and flow cytometry. The role of caspase activation was determined using fluorometric profiling and the caspase inhibitor Z-Val-Ala-Asp-fluoromethyl ketone (Z-VAD-fmk). CEACAM6 expression was suppressed by RNA interference. Using a nude mouse orthotopic xenograft model, we assessed the effect of this treatment on in vivo metastatic ability. Anoikis resistance was associated with increased CEACAM6 expression. CEACAM6-specific short interfering ribonucleic acid (siRNA), but not control siRNA, increased susceptibility to caspase-mediated anoikis, an effect abrogated by Z-VAD-fmk, and decreased Akt phosphorylation (Ser-473) under anchorage-independent conditions. CEACAM6 gene silencing reversed the acquired anoikis resistance of Mia(AR) and inhibited its in vivo metastatic ability. CEACAM6 warrants further investigation as a novel therapeutic target for the treatment of pancreatic adenocarcinoma.
失巢凋亡是正常细胞因与底物黏附不足或不适当而引发的凋亡反应。据推测，对失巢凋亡的抗性促进肿瘤发生和转移。癌胚抗原相关细胞黏附分子6（CEACAM6）是免疫球蛋白超家族成员，在多种人类癌症中过表达，并与失巢凋亡抗性有关。我们测试了CEACAM6基因沉默对胰腺腺癌细胞系失巢凋亡的影响。通过在聚甲基丙烯酸2-羟乙酯包被的孔中培养，在PANC1、Capan2、MiaPaCa2和Mia(AR)（一种源自MiaPaCa2的失巢凋亡抗性亚系）中诱导失巢凋亡。通过YO-PRO-1/碘化丙啶染色和流式细胞术对失巢凋亡进行定量。使用荧光分析和半胱天冬酶抑制剂Z-缬氨酸-丙氨酸-天冬氨酸-氟甲基酮（Z-VAD-fmk）确定半胱天冬酶激活的作用。通过RNA干扰抑制CEACAM6表达。使用裸鼠原位异种移植模型，我们评估了这种治疗对体内转移能力的影响。失巢凋亡抗性与CEACAM6表达增加有关。CEACAM6特异性小干扰核糖核酸（siRNA）而非对照siRNA增加了对半胱天冬酶介导的失巢凋亡的敏感性，Z-VAD-fmk可消除这种作用，并在非锚定条件下降低Akt磷酸化（Ser-473）。CEACAM6基因沉默逆转了Mia(AR)获得的失巢凋亡抗性，并抑制了其体内转移能力。CEACAM6作为胰腺腺癌治疗的新型治疗靶点值得进一步研究。
