Abstract 3361: Targeting tumor/cancer stem cell marker DCLK1 for the treatment of hepatocellular carcinoma and erlotinib-resistant lung adenocarcinoma using Z-3,5,4’-Trimethoxystilbene (Z-TMS)

Introduction: Tumor/cancer-initiating stem-like cells (CSCs) exhibit self-renewal and unlimited capacity for proliferation and differentiation. These cells also display propensity to reproduce original tumor after metastasis and confer resistance to anti-cancer therapies. Hepatocellular carcinoma (HCC), the third most common cause of cancer-related deaths worldwide, has been shown to possess subsets of CSCs generally marked by EpCAM and CD133 expression. We have extensively investigated doublecortin-like kinase (DCLK1) CSC marker in advanced liver diseases including cancers of liver, colon and pancreas. Our published data suggest that DCLK1 promotes inflammatory and oncogenic pathways including epithelial-mesenchymal transition. These observations prompted us to find means for targeting DCLK1-positive cells and to investigate the impacts of interference with DCLK1 on tumor growth. Methods: Cell cycle analysis of DCLK1-positive cancer cells was carried out using propidium iodide staining followed by flow cytometry. EGFR kinase assay was performed using the ADP-Glo kinase assay. Immunohistochemical staining, confocal microscopy, real-time PCR and Western blot were used for detection of CSC markers in HCC. Specific anti-DCLK1 shRNAs and a resveratrol analogue, Z-TMS, were used to inhibit DCLK1-dependent tumor growth and cell migration. Results: DCLK1 is extensively expressed in human hepatocytes-derived tumor xenografts and in the liver tissues of patients with HCC whereas normal human liver and isolated hepatocytes lack the protein expression. HCC Patients (n = 369) overexpressing DCLK1 in liver showed approximately 3 times reduction in 5-year survival rate. Z-TMS (1 μM) inhibited tumor-like growth of hepatoma cells in a magnetic levitation-based culture model. The drug induced bundling of DCLK1 with microtubules in hepatoma cells and blocked cell cycle progression at G2/M phase. Similar drug treatment of hepatoma cells triggered downregulation of CDK1, induced p21cip1/waf1 expression, and inhibited Akt-Ser473 phosphorylation. In addition, Z-TMS significantly reduced survival of erlotinib-resistant lung carcinoma (H1975) cells that contain a T790M mutation in EGFR in the 0.1 μM to 1.0 μM range within 48 hr whereas erlotinib failed to reduce cell survival even though it was fully active against the EGFR kinase domain (aa 695-1210). Conclusions: The Z-TMS9s broad-range anti-tumor activities are likely attributed to its ability of targeting DCLK1-microtubule dynamics, cell migration, cell cycle and the Akt signaling pathway. These properties may also be responsible for its inhibitory effects on erlotinib-resistant lung cancer. Citation Format: Naushad Ali, Charles B. Nguyen, Sanam Husain, Parthasarathy Chandrakesan, Randal May, Sripathi Sureban, Nathaniel Weygant, Dongfeng Qu, Danny N. Dhanasekaran, Michael Bronze, Courtney Houchen. Targeting tumor/cancer stem cell marker DCLK1 for the treatment of hepatocellular carcinoma and erlotinib-resistant lung adenocarcinoma using Z-3,5,4’-Trimethoxystilbene (Z-TMS). [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 3361.