Mamoune Asmaa, Luo Jian-Hua, Lauffenburger Douglas A, Wells Alan
Department of Pathology, 713 Scaife, University of Pittsburgh, Pittsburgh, PA 15261, USA.
Cancer Res. 2003 Aug 1;63(15):4632-40.
Mortality and morbidity of prostate cancer result from extracapsular invasion and metastasis. This tumor progression depends on active cell motility. Previous studies have shown that calpain-regulated rear detachment enabling forward locomotion is required for cell migration initiated by growth factor and adhesion receptors. Therefore, we asked whether calpain would be a target for limiting tumor progression, using as our model the PA DU-145 human prostate carcinoma cell line and a highly invasive subline, wild-type DU-145, derived from it. In vitro, the calpain-specific inhibitor CI-I (ALLN) and the preferential-but-less-specific inhibitor leupeptin decreased transmigration of both cell lines across a Matrigel barrier. These calpain inhibitors limited epidermal growth factor-induced motility but did not alter the growth rate of the tumor cells, as expected. Antisense down-regulation of the growth factor-activated calpain-2 (m-calpain) isoform also reduced transmigration and cell motility. These in vitro findings were then buttressed by in vivo studies, in which i.p. DU-145 tumor xenografts were treated with leupeptin. Tumor invasion into the diaphragm was reduced by leupeptin treatment for both the PA and wild-type DU-145 cells (from 1.7 to 0.78 for the parental line and 2.3 to 1.2 for the invasive derivative, respectively). Tumor cells of both types engineered to express calpain-2 antisense constructs also demonstrated a similar 50% reduced invasiveness in vivo. Finally, we found by gene expression survey of 53 human prostate tumors and 23 normal prostates that calpain was not up-regulated in relationship to invasiveness or metastatic activity, consistent with expectation from the biological role of this effector. Taken together, these results strongly suggest that epigenetic activation of calpain plays an important role in the invasion of human prostate cancer and that it can be targeted to reduce tumor progression.
前列腺癌的死亡率和发病率源于包膜外侵犯和转移。这种肿瘤进展依赖于活跃的细胞运动。先前的研究表明，钙蛋白酶调节的后方脱离以实现向前运动是生长因子和黏附受体引发的细胞迁移所必需的。因此，我们以PA DU - 145人前列腺癌细胞系及其衍生的高侵袭性子系野生型DU - 145为模型，探究钙蛋白酶是否会成为限制肿瘤进展的靶点。在体外，钙蛋白酶特异性抑制剂CI - I（ALLN）和优先但特异性较低的抑制剂亮抑蛋白酶肽降低了两种细胞系穿过基质胶屏障的迁移能力。正如预期的那样，这些钙蛋白酶抑制剂限制了表皮生长因子诱导的运动，但并未改变肿瘤细胞的生长速率。生长因子激活的钙蛋白酶 - 2（m - 钙蛋白酶）亚型的反义下调也降低了迁移和细胞运动能力。这些体外研究结果随后得到了体内研究的支持，在体内研究中，对腹腔注射的DU - 145肿瘤异种移植物用亮抑蛋白酶肽进行处理。亮抑蛋白酶肽处理使PA和野生型DU - 145细胞的肿瘤向膈肌的侵袭均减少（亲代细胞系从1.7降至0.78，侵袭性衍生物从2.3降至1.2）。两种类型的经基因工程改造以表达钙蛋白酶 - 2反义构建体的肿瘤细胞在体内也表现出类似的50%侵袭性降低。最后，通过对53例人类前列腺肿瘤和23例正常前列腺的基因表达调查，我们发现钙蛋白酶与侵袭性或转移活性并无上调关系，这与该效应器的生物学作用预期一致。综上所述，这些结果强烈表明钙蛋白酶的表观遗传激活在人类前列腺癌的侵袭中起重要作用，并且可以将其作为靶点来减少肿瘤进展。
