Gujral A, Burton D W, Terkeltaub R, Deftos L J
The Department of Medicine, University of California, and the Veterans Affairs Medical Center, San Diego 92161, USA.
Cancer Res. 2001 Mar 1;61(5):2282-8.
PTHrP (parathyroid hormone-related protein) overexpression by prostate carcinoma cells has been implicated in tumor progression. Although the biological effects of PTHrP can be mediated by the G-protein-coupled PTH/PTHrP receptor, PTHrP also has intracrine actions mediated by a nuclear localization sequence at residues 87-107. We investigated the effect of PTHrP transfection and treatment on production by prostate carcinoma cells of IL (interleukin)-8, which can regulate prostate cancer growth by angiogenic activity and growth-promoting effects. Six prostate cancer cell lines exhibited constitutive expression of PTHrP and IL-8 that were significantly correlated (r = 0.93; P < 0.01). We transfected wild-type and mutant PTHrP into these cells. Wild-type PTHrP1-173 and PTHrP33-173 lacking the PTH/PTHrP receptor-binding domain induced a 3-fold stimulation of IL-8 production but not production of another angiogenic factor, vascular endothelial growth factor. Transfection of the COOH-terminal truncation mutant PTHrP1-87 induced a 5-fold simulation of IL-8 and a 3-fold increase in IL-8 mRNA. Cells transfected with PTHrP1-87 and 1-173 also showed increased cell proliferation. In contrast, exogenous PTHrP1-34 and 1-86 peptides did not significantly affect IL-8 production; moreover, PTHrP-neutralizing antibodies did not inhibit the production of IL-8 by transfected PTHrP. Additional transfection studies with progressively COOH-terminally truncated PTHrP1-87 defined a 23-amino acid sequence, PTHrP65-87, required for PTHrP1-87 to robustly stimulate IL-8 in prostate cancer cells. Confocal microscopy and immunoassay demonstrated PTHrP1-87 nuclear localization. Our results demonstrate that PTHrP acts to induce IL-8 production in prostate cancer cells via an intracrine pathway independent of its classical nuclear localization sequence. This novel pathway could mediate the effects of PTHrP on the progression of prostate cancer.
前列腺癌细胞中甲状旁腺激素相关蛋白（PTHrP）的过表达与肿瘤进展有关。尽管PTHrP的生物学效应可由G蛋白偶联的甲状旁腺激素/PTHrP受体介导，但PTHrP也具有由87 - 107位残基处的核定位序列介导的自分泌作用。我们研究了PTHrP转染和处理对前列腺癌细胞产生白细胞介素（IL）-8的影响，IL-8可通过血管生成活性和促生长作用来调节前列腺癌的生长。六种前列腺癌细胞系表现出PTHrP和IL-8的组成性表达，二者显著相关（r = 0.93；P < 0.01）。我们将野生型和突变型PTHrP转染到这些细胞中。缺乏甲状旁腺激素/PTHrP受体结合域的野生型PTHrP1 - 173和PTHrP33 - 173可诱导IL-8产生增加3倍，但对另一种血管生成因子血管内皮生长因子的产生没有影响。COOH末端截短突变体PTHrP1 - 87的转染可诱导IL-8增加5倍，IL-8 mRNA增加3倍。用PTHrP1 - 87和1 - 173转染的细胞也显示出细胞增殖增加。相比之下，外源性PTHrP1 - 34和1 - 86肽对IL-8的产生没有显著影响；此外，PTHrP中和抗体不能抑制转染的PTHrP诱导的IL-8产生。用逐渐COOH末端截短的PTHrP1 - 87进行的额外转染研究确定了一个23个氨基酸的序列PTHrP65 - 87，它是PTHrP1 - 87在前列腺癌细胞中强烈刺激IL-8所必需的。共聚焦显微镜和免疫测定显示PTHrP1 - 87的核定位。我们的结果表明，PTHrP通过一种独立于其经典核定位序列的自分泌途径诱导前列腺癌细胞产生IL-8。这一新途径可能介导PTHrP对前列腺癌进展的影响。
