Williams Tiffany, Kole Ryszard
Curriculum in Genetics and Molecular Biology, UNC Lineberger Comprehensive Cancer Center, University of North Carolina, Chapel Hill, NC 27599-7295, USA.
Oligonucleotides. 2006 Summer;16(2):186-95. doi: 10.1089/oli.2006.16.186.
The prostate-specific membrane antigen (PSMA), a product of the folate hydrolase (FOLH1) gene, is highly expressed as a largely extracellular membrane-anchored protein in malignant prostate tissues and in nonprostatic tumor neovasculature. Treatment of prostate cancer LNCap cells with spliceswitching oligonucleotides (SSOs) modulated splicing of FOLH1 pre-mRNA from the full-length PSMA splice variant to three splice variants: the cytoplasmic PSM', alternatively spliced at exon 1, and the previously unexamined PSMADelta6 and PSMADelta18 variants, which lack exons 6 and 18, respectively. Application of SSOs decreased membrane PSMA levels and increased PSM', PSMADelta6, and PSMADelta18 transcripts. As a result, PSM' protein was translocated to the cytoplasm, and switching to PSMADelta6 and PSMADelta18 downregulated PSMA expression. NAALADase assays showed that PSM' retained enzymatic activity. PSMADelta6 and PSMADelta18 were not active, presumably due to a change in a reading frame that eliminated the NAALDase active site or the dimerization domain or both in these proteins.
前列腺特异性膜抗原（PSMA）是叶酸水解酶（FOLH1）基因的产物，在恶性前列腺组织和非前列腺肿瘤新生血管中作为一种主要锚定在细胞外膜的蛋白质高度表达。用剪接转换寡核苷酸（SSO）处理前列腺癌LNCap细胞可调节FOLH1前体mRNA的剪接，使其从全长PSMA剪接变体转变为三种剪接变体：细胞质中的PSM'，在第1外显子处选择性剪接；以及之前未研究过的PSMΔ6和PSMΔ18变体，它们分别缺少第6和第18外显子。应用SSO可降低膜PSMA水平，并增加PSM'、PSMΔ6和PSMΔ18转录本。结果，PSM'蛋白转移到细胞质中，而转换为PSMΔ6和PSMΔ18可下调PSMA表达。N-乙酰-α-半乳糖胺酶（NAALADase）分析表明，PSM'保留了酶活性。PSMΔ6和PSMΔ18无活性，推测是由于阅读框的改变消除了这些蛋白质中的NAALADase活性位点或二聚化结构域或两者。
