National Toxicology Program Laboratory, Inorganic Toxicology Group, Division of the National Toxicology Program, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
Toxicol Sci. 2012 Jan;125(1):20-9. doi: 10.1093/toxsci/kfr282. Epub 2011 Oct 19.
Arsenic is a human skin carcinogen. Cancer is probably a disease driven by stem cells (SCs), and SCs are likely a key target during arsenic oncogenesis. In utero arsenic exposure predisposes mice to skin cancers that overproduce cancer SCs (CSCs) and have distorted CSC signaling and population dynamics. Therefore, we hypothesized CSC accumulation may occur during arsenic-induced malignant transformation in vitro of human skin keratinocytes. Thus, the HaCaT cell line, malignantly transformed by arsenite (100 nM, 30 weeks; termed As-TM cells) in prior work, was further studied for the quantity and nature of SCs after this transformation. SCs were isolated from passage-matched control and As-TM cells by a magnetic bead system that enriches for CD34-positive cells. There were 2.5 times more SCs isolated from As-TM cells than control. Holoclone production from As-TM putative CSCs was 2.5-fold higher by 1 week and 3.5-fold higher by 2 weeks than control SCs. Potential malignant phenotype was assessed in isolated SC/CSCs. Transcript level of SC/CSC markers were elevated in both isolated As-TM CSCs and control SCs compared with parental cells, but compared with control SCs, As-TM putative CSCs had elevated CD34, K5, K14, K15, and K19 transcripts and dramatically stronger staining for p63, Rac1, K5, Notch1, and K19. As-TM putative CSCs also showed markedly elevated MMP-9 secretion and colony formation, indicators of cancer phenotype, even compared with total population of As-TM cells. Thus, malignant phenotype is particularly pronounced in CSCs after arsenic-induced transformation of human skin cells and occurs concurrently with a potential overproduction of these cells.
砷是一种人类皮肤致癌物。癌症可能是由干细胞（SCs）驱动的疾病，SCs 很可能是砷致癌过程中的关键靶点。子宫内砷暴露使小鼠易患过度产生癌症干细胞（CSCs）且 CSC 信号和群体动力学发生扭曲的皮肤癌。因此，我们假设 CSC 的积累可能发生在体外砷诱导的人皮肤角质形成细胞恶性转化过程中。因此，在先前的研究中，使用亚砷酸盐（100 nM，30 周；称为 As-TM 细胞）使 HaCaT 细胞系恶性转化后，进一步研究了这些转化后 SCs 的数量和性质。通过一个富集 CD34 阳性细胞的磁珠系统，从传代匹配的对照和 As-TM 细胞中分离 SCs。从 As-TM 细胞中分离出的 SCs 是对照细胞的 2.5 倍。As-TM 潜在 CSCs 的全克隆形成在第 1 周时比对照 SCs 高 2.5 倍，在第 2 周时高 3.5 倍。在分离的 SC/CSCs 中评估潜在的恶性表型。与亲本细胞相比，分离的 As-TM CSCs 和对照 SCs 中的 SC/CSC 标志物的转录水平升高，但与对照 SCs 相比，As-TM 潜在 CSCs 中 CD34、K5、K14、K15 和 K19 的转录水平升高，p63、Rac1、K5、Notch1 和 K19 的染色强度更强。As-TM 潜在 CSCs 还表现出明显升高的 MMP-9 分泌和集落形成，这是癌症表型的指标，甚至与 As-TM 细胞的总群体相比也是如此。因此，在人皮肤细胞经砷诱导转化后，恶性表型在 CSCs 中尤其明显，并且与这些细胞的潜在过度产生同时发生。
