Schlafen-3 decreases cancer stem cell marker expression and autocrine/ juxtacrine signaling in FOLFOX-resistant colon cancer cells

Phil-Sun Oh, Vaishali B. Patel, Matthew A Sanders, Shailender S. Kanwar, Yingjie Yu, Jyoti Nautiyal, Bhaumik B. Patel, Adhip P.N. Majumdar

Abstract

We have previously demonstrated that expression of the novel gene schlafen (Slfn)-3 correlates with intestinal epithelial cell differentiation. The current investigation was undertaken to examine whether Slfn-3 plays a role in regulating differentiation of FOLFOX-resistant (5-Fluorouracil + oxaliplatin) colon cancer cells that are highly enriched in cancer stem cells (CSCs). Transfection of Slfn-3 in FOLFOX-resistant colon cancer HCT-116 cells resulted in increase of alkaline phosphatase (ALP) activity, a marker of intestinal differentiation. Additionally, Slfn-3 transfection resulted in reduction of mRNA and protein levels of the CSC markers CD44, CD133, CD166, and aldehyde dehydrogenase 1 (ALDH1) in both FOLFOX-resistant HCT-116 and HT-29 cells. This was accompanied by decreased formation of tumorosphere/colonosphere (an in vitro model of tumor growth) in stem cell medium and inhibition of expression of the chemotherapeutic drug transporter protein ABCG2. Additionally, Slfn-3 transfection of FOLFOX-resistant HCT-116 and HT-29 cells reduced Hoechst 33342 dye exclusion. Finally, Slfn-3 transfection inhibited the expression of transforming growth factor-α (TGF-α) in both FOLFOX-resistant colon cancer cells but stimulated apoptosis in response to additional FOLFOX treatment. In summary, our data demonstrate that Slfn-3 expression inhibits multiple characteristics of CSC-enriched FOLFOX-resistant colon cancer cells including induction of differentiation and reduction in tumorosphere/colonosphere formation, drug transporter activity and autocrine stimulation of proliferation. Thus, Slfn-3 expression may render colon CSCs more susceptible to cancer chemotherapeutics.

  • Differentiation
  • cancer stem cell
  • transforming growth factor-alpha
  • drug exclusion
  • ABCG2