Mitchell Cancer Institute, University of South Alabama, 1660 Springhill Avenue, Mobile, AL 36604, USA.
BMC Med. 2010 Feb 17;8:14. doi: 10.1186/1741-7015-8-14.
Melanoma incidence is on the rise and advanced melanoma carries an extremely poor prognosis. Treatment options, including chemotherapy and immunotherapy, are limited and offer low response rates and transient efficacy. Thus, identification of new melanocyte/melanoma antigens that serve as potential novel candidate biomarkers in melanoma is an important area for investigation.
Full length MITF-M and its splice variant cDNA were cloned from human melanoma cell line 624 mel by reverse transcription polymerase chain reaction (RT-PCR). Expression was investigated using regular and quantitative RT-PCR in three normal melanocytes (NHEM), 31 melanoma cell lines, 21 frozen melanoma tissue samples, 18 blood samples (peripheral blood mononuclear cell; PBMC) from healthy donors and 12 non-melanoma cancer cell lines, including three breast, five glioma, one sarcoma, two kidney and one ovarian cancer cell lines.
A novel splice variant of MITF-M, which we named MITF-Mdel, was identified. The predicted MITF-Mdel protein contains two in frame deletions, 56- and 6- amino acid deletions in exon 2 (from V32 to E87) and exon 6 (from A187 to T192), respectively. MITF-Mdel was widely expressed in melanocytes, melanoma cell lines and tissues, but almost undetectable in non-melanoma cell lines or PBMC from healthy donors. Both isoforms were expressed significantly higher in melanoma tissues than in cell lines. Two of 31 melanoma cell lines expressed only one isoform or the other.
MITF-Mdel, a novel melanocyte/melanoma-specific isoform of MITF-M, may serve as a potential candidate biomarker for diagnostic and follow-up purposes in melanoma.
黑色素瘤的发病率正在上升，晚期黑色素瘤的预后极差。治疗选择包括化疗和免疫疗法，但反应率低且疗效短暂。因此，鉴定新的黑素细胞/黑色素瘤抗原作为黑色素瘤的潜在新型候选生物标志物是一个重要的研究领域。
通过反转录聚合酶链反应（RT-PCR）从人黑色素瘤细胞系 624mel 中克隆全长 MITF-M 及其剪接变体 cDNA。使用常规和定量 RT-PCR 在三种正常黑素细胞（NHEM）、31 种黑色素瘤细胞系、21 种冷冻黑色素瘤组织样本、18 份来自健康供体的外周血单核细胞（PBMC）和 12 种非黑色素瘤癌细胞系中研究表达情况，包括三种乳腺癌、五种神经胶质瘤、一种肉瘤、两种肾癌和一种卵巢癌细胞系。
鉴定了 MITF-M 的一种新剪接变体，我们将其命名为 MITF-Mdel。预测的 MITF-Mdel 蛋白包含两个框内缺失，分别在第 2 外显子（从 V32 到 E87）和第 6 外显子（从 A187 到 T192）中缺失 56-和 6-个氨基酸。MITF-Mdel 在黑素细胞、黑色素瘤细胞系和组织中广泛表达，但在非黑色素瘤细胞系或健康供体的 PBMC 中几乎无法检测到。两种同工型在黑色素瘤组织中的表达均明显高于细胞系。31 种黑色素瘤细胞系中有两种仅表达一种同工型或另一种同工型。
MITF-Mdel 是 MITF-M 的一种新型黑素细胞/黑色素瘤特异性同工型，可能作为黑色素瘤诊断和随访的潜在候选生物标志物。
