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Supplementary Figures from Tankyrase Inhibitors Target Colorectal Cancer Stem Cells via AXIN-Dependent Downregulation of c-KIT Tyrosine Kinase

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posted on 2023-04-03, 18:26 authored by Myung-Kyu Jang, Tetsuo Mashima, Hiroyuki Seimiya

Supplementary Figure 1 shows morphology, growth and plasticity of the CD44-positive and -negative COLO-320DM cells. Supplementary Figure 2 shows that tankyrase inhibitors preferentially target CD44-positive COLO-320DM cells. Supplementary Figure 3 shows that tankyrase inhibitors decrease the CD44-positive cell populations in colorectal cancer cells. Supplementary Figure 4 shows that tankyrase inhibitors upregulate AMOTL1 to comparable levels in CD44-positive and -negative COLO-320DM cells. Supplementary Figure 5 shows c-KIT expression in colorectal cancer cell lines. Supplementary Figure 6 shows that c-KIT depletion inhibits proliferation of CD44-positive COLO-320DM cells. Supplementary Figure 7 shows difficulties in detecting c-KIT phosphorylation in colorectal cancer cells under the normal growth conditions. Supplementary Figure 8 shows c-KIT phosphorylation induced by stem cell factor in CD44-positive COLO-320DM cells and its downregulation by tankyrase inhibitors. Supplementary Figure 9 shows that c-KIT overexpression strengthens resistance of DLD-1 cells to tankyrase inhibitors. Supplementary Figure 10 shows that G007-LK does not significantly destabilize c-KIT protein in COLO-320DM cells. Supplementary Figure 11 shows negative effect of imatinib on CD44-positive cell populations in COLO-320DM and DLD-1 cells. Supplementary Figure 12 shows that AXIN2 knockdown blocks c-KIT downregulation in G007-LK-treated colorectal cancer cells. Supplementary Figure 13 shows that G007-LK does not affect the stability of c-KIT mRNA in COLO-320DM and DLD-1 cells. Supplementary Figure 14 shows that tankyrase inhibitors downregulate c-KIT promoter activity in an AXIN2-dependent manner in DLD-1 cells. Supplementary Figure 15 shows that tankyrase inhibitors do not significantly downregulate SP1 protein levels in COLO-320DM and DLD-1 cells. Supplementary Figure 16 shows that tankyrase inhibitors downregulate JNK phosphorylation levels in CD44-positive COLO-320DM cells. Supplementary Figure 17 shows that G007-LK upregulates AXIN2 and downregulates c-KIT in vivo. Supplementary Figure 18 shows that tankyrase inhibitors do not enhance the therapeutic efficacy of irinotecan on DLD-1 xenograft tumors in vivo.

Funding

Ministry of Education, Culture, Sports, Science and Technology

Japanese Foundation for Cancer Research

Japan Society for the Promotion of Science

Japan Agency for Medical Research and Development

Nippon Foundation

Princess Takamatsu Cancer Research Fund

History

ARTICLE ABSTRACT

Cancer stem cells (CSC) constitute heterogeneous cell subpopulations of a tumor. Although targeting CSCs is important for cancer eradication, no clinically approved drugs that target CSCs have been established. Tankyrase poly(ADP-ribosyl)ates and destabilizes AXIN, a negative regulator of β-catenin, and promotes β-catenin signaling. Here, we report that tankyrase inhibitors downregulate c-KIT tyrosine kinase and inhibit the growth of CD44-positive colorectal CSCs. c-KIT expression in CD44-positive subpopulations of colorectal cancer COLO-320DM cells is associated with their tumor-initiating potential in vivo. Tankyrase inhibitors downregulate c-KIT expression in established cell lines, such as COLO-320DM and DLD-1, and colorectal cancer patient–derived cells. These effects of tankyrase inhibitors are caused by reducing the recruitment of SP1 transcription factor to the c-KIT gene promoter and depend on AXIN2 stabilization but not β-catenin downregulation. Whereas c-KIT knockdown inhibits the growth of CD44-positive COLO-320DM cells, c-KIT overexpression in DLD-1 cells confers resistance to tankyrase inhibitors. Combination of a low-dose tankyrase inhibitor and irinotecan significantly inhibited the growth of COLO-320DM tumors in a mouse xenograft model. These observations suggest that tankyrase inhibitors target c-KIT–positive colorectal CSCs and provide a novel therapeutic strategy for cancer.