iNOS promotes CD24+CD133+ liver cancer stem cell phenotype through a TACE/ADAM17-dependent Notch signaling pathway

By Rong-hua Wang, Yawen Li, A. Tsung, Hai Huang, Q. Du, Muqing Yang, M. Deng, S. Xiong, Xiju Wang, Liyong Zhang and 3 more. 2018

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Significance CD24+CD133+ liver cancer stem cells (LCSCs) express higher levels of the inducible nitric oxide synthase (iNOS) and possess self-renewal and tumor growth properties. iNOS is associated with more aggressive hepatocellular carcinoma (HCC), leading to the upregulation of Notch1 signaling. The activation of Notch1 by iNOS/NO is dependent on cGMP/PKG-mediated activation of TACE and upregulation of iRhom-2. The expression of iNOS, CD24, and CD133 correlates with the expression of activated TACE and Notch signaling in more aggressive human HCC. These findings have implications for understanding how LCSCs are regulated in the setting of chronic inflammation, where signals to upregulate iNOS are often present. Targeting iNOS could have therapeutic benefit in HCC. The inducible nitric oxide synthase (iNOS) is associated with more aggressive solid tumors, including hepatocellular carcinoma (HCC). Notch signaling in cancer stem cells promotes cancer progression and requires Notch cleavage by ADAM (a disintegrin and metalloprotease) proteases. We hypothesized that iNOS/NO promotes Notch1 activation through TACE/ADAM17 activation in liver cancer stem cells (LCSCs), leading to a more aggressive cancer phenotype. Expression of the stem cell markers CD24 and CD133 in the tumors of patients with HCC was associated with greater iNOS expression and worse outcomes. The expression of iNOS in CD24+CD133+ LCSCs, but not CD24−CD133− LCSCs, promoted Notch1 signaling and stemness characteristics in vitro and in vivo, as well as accelerating HCC initiation and tumor formation in the mouse xenograft tumor model. iNOS/NO led to Notch1 signaling through a pathway involving the soluble guanylyl cyclase/cGMP/PKG-dependent activation of TACE/ADAM17 and up-regulation of iRhom2 in LCSCs. In patients with HCC, higher TACE/ADAM17 expression and Notch1 activation correlated with poor prognosis. These findings link iNOS to Notch1 signaling in CD24+CD133+ LCSCs through the activation of TACE/ADAM17 and identify a mechanism for how iNOS contributes to progression of CD24+CD133+ HCC.

Subfields: Molecular Biology, Oncology

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  1. Pengfei Shi
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  3. Zhen Dong
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  6. Jiayi Zhang
  7. Wen Peng
  8. Guanghui Zhang

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