CD133 marks a myogenically primitive subpopulation in rhabdomyosarcoma cell lines that are relatively chemoresistant but sensitive to mutant HSV

Abstract

Background Rhabdomyosarcoma (RMS) is characterized by features of skeletal muscle and is comprised of two major histological subtypes, embryonal (E-RMS) and alveolar (A-RMS). Subsets of each RMS subtype demonstrate resistance to multimodal therapy leading to treatment failure. Cancer stem cells or cancer-initiating cells (CIC) represent a theorized population of cells that give rise to tumors and are responsible for treatment resistance. Procedure We investigated the ability of CD133, a putative CIC marker, to distinguish a chemoresistant, myogenically primitive population in alveolar (RH30) and embryonal (RD) RMS cell lines. We tested CD133+/- cells for sensitivity to engineered herpes simplex virus (oHSV) Results Relative to CD133- cells, CD133+ A-RMS and E-RMS cells demonstrate an enhanced colony-forming ability, are less differentiated myogenically, and are more resistant to cytotoxic chemotherapy but equally sensitive to oHSV oncolysis. Compared to CD133- RD cells, CD133+ cells express relatively high levels of genes typically expressed in skeletal muscle progenitor satellite cells including PAX7, c-MET, and the GLI effectors of the hedgehog signaling pathway. In contrast, CD133+ RH30 cells were not associated with enhanced expression of satellite cell markers or Hh targets. Conclusions Our findings demonstrate that CD133+ cells from A-RMS and E-RMS cell lines are characterized by a myogenically primitive phenotype. These cells have the capacity to form colonies in vitro and are more resistant to chemotherapy than CD133- cells. CD133 expression may denote a subset of RMS cells with an important role in tumorigenesis and treatment failure. These resistant cells may be effectively targeted by oHSV therapy.

Atypical nuclear localization of CD133 plasma membrane glycoprotein in rhabdomyosarcoma cell lines

“…In our previous studies, we identified CD133-positive cells that presented typical membrane positivity in two of the most common types of pediatric sarcomas, osteosarcoma ( 5 ) and rhabdomyosarcoma (RMS) ( 6 ). The expression of CD133 in these two solid tumors, as well as the tumorigenicity of CD133-positive cells, has been confirmed by other research groups ( 7 – 10 ). Therefore, CD133 is currently accepted as one of the markers of a CSC phenotype in pediatric sarcomas, including RMS ( 11 – 13 ).…”

“…Although certain micrographs from our previous study showed cells with an accumulation of fluorescent signal for CD133 in the nucleus ( 6 ), we assumed that this finding was an artifact resulting from the use of a rabbit polyclonal antibody against CD133, (which was the only anti-CD133 antibody available at the time), although we had never detected similar nuclear positivity for CD133 in osteosarcoma or glioblastoma cell lines using the same antibody ( 5 , 18 ). Other authors investigating CD133 expression in RMS and RMS cell lines have not described the pattern of CD133 positivity in detail, and no micrographs of the individual cells are available in their published articles ( 9 , 10 ).…”

Aldehyde Dehydrogenase 1 (ALDH1) Is a Potential Marker for Cancer Stem Cells in Embryonal Rhabdomyosarcoma

“…Although ALDH1 high cells of RH30 cells were detected, unexpectedly the ALDH1 high cells of aRMS did not form colonies or spheres (data not shown). A likely explanation of this phenomenon is that the two major RMS subtypes arise from different cells of origin, given the substantial clinical and biological distinctions between them, as reported previously by Pressey et al [ 34 ]. We are currently planning to examine whether ALDH1 can be used as a marker in other aRMS cell lines.…”

FGFR4 signaling couples to Bim and not Bmf to discriminate subsets of alveolar rhabdomyosarcoma cells

“…About 80% of aRMS are associated with chromosomal translocations generating fusion transcription factors PAX3/FOXO1 or PAX7/FOXO1 which induce expression of a specific gene expression signature. [3][4][5] While for eRMS cellular hierarchy has been recently discovered, [6][7][8] no further functional subclassification of aRMS tumor cells has been described up to date. However, current treatment approaches are only effective in a subgroup of aRMS patients with 5-year survival rate being only about 48%.…”