Abstract 4147: DCLK1 a novel therapeutic target in non-small cell lung cancer
Authors: Chandrakesan Parthasarathy , Qu Dongfeng , May Randal , Weygant Nathaniel , Berry William , Ali Naushad , Sureban Sripathi , Bannerman-Menson Eddie , Bronze Michael , Houchen Courtney 
Published: July 2017

Abstract
Introduction: Lung cancers possess a rare population of cells that have the capacity to self-renew, differentiation and ultimately promote tumorigenesis. These cells are often resistance to conventional therapies and are responsible for tumor relapse and metastatic spread, which contribute to the overall mortality observed in non-small cell lung cancer (NSCLC). These cells are termed tumor stem cells (TSCs) and as such are highly desirable targets for novel therapeutic strategies. Doublecortin-like Kinase 1 (DCLK1) has recently been identified as a tumor stem cell marker in the intestine and pancreas and is dysregulated in many solid tumor cancers including lung cancer. Increased expression has been demonstrated to correlate with poor survival in several solid tumor cancers. Thus these data taken together provide the rational for targeting DCLK1 expressing cells in NSCLC.
Methods: Small interfering RNA (siRNA) against DCLK1 was transfected into NSCLC cell lines (A549 - wt-p53; H1299 –homozygous deletion of p53) of highly drug resistant (A549) and metastatic (H1299). Cell proliferation, colony formation, self-renewal, cell migration and invasion and drug resistance assays were performed to assess the tumor stem cell characteristics. A549 cells were treated with siDCLK1 and cisplatin in order to assess the role of DCLK1 to reverse the drug-resistance. A549 cells were utilized to generate tumor xenograft in order to assess the role of DCLK1 knockdown on NSCLC tumorigenesis in vivo. The data were generated utilizing experimental protocols for clonogenic culture, immunohistochemistry, RT-qPCR and Western blotting.
Results: Silencing DCLK1 via RNA interference decreased the colony formation (p&lt;0.001), and self-renewal ability (p&lt;0.0001) of the NSCLC cell lines in vitro. Knocking down DCLK1 reduced (p&lt;0.001) NSCLC cells migration and invasion in vitro. Furthermore, DCLK1 knockdown decreased the expression of EMT associated factors (Slug, Snail, Twist, Zeb1/2, Vimentin) and pluripotency factors. Initial cisplatin treatment results in the isolation of cisplatin resistant A549 cells. Retreatment of cisplatin resistant A549 cells results in greater resistance and survival ability. However, combination therapy of these resistance cells with siDCLK1 and cisplatin overcame cisplatin-induced resistance, resulting in greater cell death compared to cisplatin or siDCLK1 alone treatments. Nanoparticle encapsulated siDCLK1 treatment in xenograft tumors resulted in tumor growth arrest in vivo.
Conclusions: NSCLC cells highly express DCLK1 display enhanced self-renewal, increased migration and invasion. Combination therapy of siDCLKL1 with cisplatin overcame cisplatin induced drug resistance. Targeting DCLK1 reduced tumor xenograft in vivo. Taken together these data suggest that DCLK1 inhibition reduces TSC related properties, overcome drug resistance and inhibits tumor growth, thus making DCLK1 targeted therapy an attractive tool for combating NSCLC.
Citation Format: Parthasarathy Chandrakesan, Dongfeng Qu, Randal May, Nathaniel Weygant, William Berry, Naushad Ali, Sripathi Sureban, Eddie Bannerman-Menson, Michael Bronze, Courtney Houchen. DCLK1 a novel therapeutic target in non-small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4147. doi:10.1158/1538-7445.AM2017-4147