Farias Luz María Barajas, Ocaña Deysi Bermúdez, Díaz Lorenza, Larrea Fernando, Avila-Chávez Euclides, Cadena Adriana, Hinojosa Luz María, Lara Gerardo, Villanueva Luis Alberto, Vargas Carlos, Hernández-Gallegos Elizabeth, Camacho-Arroyo Ignacio, Dueñas-González Alfonso, Pérez-Cárdenas Enrique, Pardo Luis A, Morales Angélica, Taja-Chayeb Lucía, Escamilla Juan, Sánchez-Peña Carmen, Camacho Javier
Pharmacology Section, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, México City, México.
Cancer Res. 2004 Oct 1;64(19):6996-7001. doi: 10.1158/0008-5472.CAN-04-1204.
Ether a go-go (EAG) potassium channels display oncogenic properties. In normal tissues, EAG mRNA is almost exclusively expressed in brain, but it is expressed in several somatic cancer cell lines, including HeLa, from cervix. Antisense experiments against eag reduce cell proliferation in some cancer cell lines, and inhibition of EAG-mediated currents has been suggested to decrease cell proliferation in a melanoma cell line. Because of the potential clinical relevance of EAG, we investigated EAG mRNA expression in the following fresh samples from human uterine cervix: 5 primary cultures obtained from cancerous biopsies, 1 cancerous fresh tissue, and 12 biopsies of control normal tissue. All of the control cervical samples came from patients with negative pap smears. Reverse transcription-PCR and Southern-blot experiments revealed eag expression in 100% of the cancerous samples and in 33% of the normal biopsies. Immunochemistry experiments showed the presence of EAG channel protein in cells from the primary cultures and in cervical cancer biopsies sections from the same patients. In addition, we looked for EAG-mediated currents in the cultures from cervical cancer cells. Here we show for the first time EAG channel activity in human tumors. Patch-clamp recordings showed typical EAG-mediated currents modulated by magnesium and displaying a pronounced Cole-Moore shift. Because EAG expression and channel activity have been suggested to be important in cell proliferation, our findings strongly support the idea of considering EAG as a tumor marker as well as a potential membrane therapeutic target for cervical cancer.
超极化激活环核苷酸门控（EAG）钾通道具有致癌特性。在正常组织中，EAG mRNA几乎仅在脑中表达，但在包括源自子宫颈的HeLa细胞系在内的几种体细胞癌细胞系中也有表达。针对eag的反义实验可降低某些癌细胞系中的细胞增殖，并且有人提出抑制EAG介导的电流可减少黑色素瘤细胞系中的细胞增殖。鉴于EAG潜在的临床相关性，我们研究了来自人子宫颈的以下新鲜样本中EAG mRNA的表达：5份取自癌组织活检的原代培养物、1份癌新鲜组织以及12份对照正常组织活检。所有对照宫颈样本均来自巴氏涂片检查阴性的患者。逆转录聚合酶链反应（RT-PCR）和Southern印迹实验显示，100%的癌样本和33%的正常活检样本中有eag表达。免疫化学实验表明，原代培养细胞以及同一患者的子宫颈癌活检切片细胞中存在EAG通道蛋白。此外，我们在子宫颈癌细胞培养物中寻找EAG介导的电流。在此我们首次展示了人类肿瘤中的EAG通道活性。膜片钳记录显示典型的EAG介导电流受镁调节，并呈现出明显的科尔-穆尔移位。由于有人提出EAG表达和通道活性在细胞增殖中很重要，我们的研究结果有力地支持了将EAG视为子宫颈癌的肿瘤标志物以及潜在膜治疗靶点的观点。
