Identification and Characterization of Cancer Stem-Like Cells in ALK-Positive Anaplastic Large Cell Lymphoma Using the SORE6 Reporter.

Will Chen,Raymond Lai,Chuquan Shang,Bardes Hassan,Moinul Haque,Jing Li,Dongzhe Liu

doi:10.3390/cimb43020041

Abstract

Transcription factors Sox2 and Oct4 are essential in maintaining the pluripotency of embryonic stem cells and conferring stemness in cancer stem-like (CSL) cells. SORE6, an in-vitro reporter system, was designed to quantify the transcription activity of Sox2/Oct4 and identify CSL cells in non-hematologic cancers. Using SORE6, we identified and enriched CSL cells in ALK-positive anaplastic large cell lymphoma (ALK + ALCL). Two ALK + ALCL cell lines, SupM2 and UCONN-L2, contained approximately 20% of SORE6+ cells, which were purified based on their expression of green fluorescent protein. We then performed functional studies using single-cell clones derived from SORE6− and SORE6+ cells. Compared to SORE6− cells, SORE6+ cells were significantly more chemoresistant and clonogenic in colony-formation assays. Sox2/Oct4 are directly involved in conferring these CSL properties, since the shRNA knockdown of Sox2 in SORE6+ significantly lowered their chemoresistance, while enforced expression of Sox2/Oct4 in SORE6− cells produced opposite effects. Using Western blots, we found that the expression and subcellular localization of Sox2/Oct4 were similar between SORE6− and SORE6+ cells. However, in SORE6+ but not SORE6− cells, Sox2 and Oct4 abundantly bound to a probe containing the SORE6 consensus sequence. c-Myc, previously shown to regulate cancer stemness in ALK + ALCL, regulated the SORE6 activity. In conclusion, SORE6 is useful in identifying/enriching CSL cells in ALK + ALCL.

Highlights

anaplastic lymphoma kinase (ALK)-positive anaplastic large cell lymphoma (ALK + ALCL) is a distinct type of non-Hodgkin lymphoma of T-cell lineage occurring most frequently in young adults and children [1,2,3,4]
Recent studies in cancer biology have postulated that cancer relapses might be attributed to the existence of a small subpopulation of cancer stem cells that are characterized by high levels of chemoresistance, self-renewal, and pluripotency [11,12]
Since the SORE6 reporter was originally designed to detect the transcription activity of Sox2 and Oct4, two of the four originally described inducible pluripotent stem cell (iPS) factors, we examined the protein expression of these two proteins in a cohort of five ALK + ALCL cell lines including SupM2, Karpas 299, UCONN-L2, SU-DHL-1, and SR2

Summary

Introduction

ALK-positive anaplastic large cell lymphoma (ALK + ALCL) is a distinct type of non-Hodgkin lymphoma of T-cell lineage occurring most frequently in young adults and children [1,2,3,4]. Recent studies in cancer biology have postulated that cancer relapses might be attributed to the existence of a small subpopulation of cancer stem cells that are characterized by high levels of chemoresistance, self-renewal, and pluripotency [11,12]. In this model, the majority of tumors are typically eradicated by most traditional cancer treatments, but the cancer stem cells persist and provide the seeds for disease relapses, at which time tumors will become more chemoresistant than those found at the initial presentation [13,14,15]

Objectives

Methods

Results

Conclusion