He Xiaoping, Khurana Ashwani, Roy Debarshi, Kaufmann Scott, Shridhar Viji
Department of Laboratory Medicine and Experimental Pathology, Mayo Clinic College of Medicine, Rochester, MN.
Int J Cancer. 2014 Oct 15;135(8):1783-9. doi: 10.1002/ijc.28818. Epub 2014 Mar 28.
The expression of human Sulfatase1 (HSulf-1) is downregulated in the majority of primary ovarian cancer tumors, but the functional consequence of this downregulation remains unclear. Using two different shRNAs (Sh1 and Sh2), HSulf-1 expression was stably downregulated in ovarian cancer OV202 cells. We found that HSulf-1-deficient OV202 Sh1 and Sh2 cells formed colonies in soft agar. In contrast, nontargeting control (NTC) shRNA-transduced OV202 cells did not form any colonies. Moreover, subcutaneous injection of OV202 HSulf-1-deficient cells resulted in tumor formation in nude mice, whereas OV202 NTC cells did not. Also, ectopic expression of HSulf-1 in ovarian cancer SKOV3 cells significantly suppressed tumor growth in nude mice. Here, we show that HSulf-1-deficient OV202 cells have markedly decreased expression of proapoptotic Bim protein, which can be rescued by restoring HSulf-1 expression in OV202 Sh1 cells. Enhanced expression of HSulf-1 in HSulf-1-deficient SKOV3 cells resulted in increased Bim expression. Decreased Bim levels after loss of HSulf-1 were due to increased p-ERK, because inhibition of ERK activity with PD98059 resulted in increased Bim expression. However, treatment with a PI3 kinase/AKT inhibitor, LY294002, failed to show any change in Bim protein level. Importantly, rescuing Bim expression in HSulf-1 knockdown cells significantly retarded tumor growth in nude mice. Collectively, these results suggest that loss of HSulf-1 expression promotes tumorigenicity in ovarian cancer through regulating Bim expression.
在大多数原发性卵巢癌肿瘤中，人类硫酸酯酶1（HSulf-1）的表达下调，但其下调的功能后果仍不清楚。使用两种不同的短发夹RNA（Sh1和Sh2），在卵巢癌OV202细胞中稳定下调了HSulf-1的表达。我们发现，缺乏HSulf-1的OV202 Sh1和Sh2细胞在软琼脂中形成集落。相比之下，转导非靶向对照（NTC）短发夹RNA的OV202细胞未形成任何集落。此外，皮下注射缺乏HSulf-1的OV202细胞导致裸鼠形成肿瘤，而OV202 NTC细胞则不会。同样，在卵巢癌SKOV3细胞中异位表达HSulf-1可显著抑制裸鼠肿瘤生长。在此，我们表明，缺乏HSulf-1的OV202细胞中促凋亡Bim蛋白的表达明显降低，在OV202 Sh1细胞中恢复HSulf-1表达可挽救这一现象。在缺乏HSulf-1的SKOV3细胞中增强HSulf-1的表达导致Bim表达增加。HSulf-1缺失后Bim水平降低是由于p-ERK增加，因为用PD98059抑制ERK活性会导致Bim表达增加。然而，用PI3激酶/AKT抑制剂LY294002处理未能显示Bim蛋白水平有任何变化。重要的是，在敲低HSulf-1的细胞中挽救Bim表达可显著延缓裸鼠肿瘤生长。总体而言，这些结果表明，HSulf-1表达缺失通过调节Bim表达促进卵巢癌的致瘤性。
