Cancer stem cells are enriched in Fanconi anemia head and neck squamous cell carcinomas

Abstract

Fanconi anemia (FA) patients have an increased risk of head and neck squamous cell carcinoma (HNSCC) at a higher rate with no apparent risk factors. HNSCC of FA patients is an aggressive tumor characterized by multifocal origin, early metastases and frequent recurrences. Given that cancer stem cells (CSC) drive tumorigenesis, tumor recurrence and metastasis, in this study, we characterized the CSC population in FA and sporadic HNSCC. The Aldefluor assay was used to characterize and isolate CSC with high aldehyde dehydrogenase (AL DH) activity (AL DHpos) in cell lines derived from FA and sporadic HNSCC. Isolated AL DHpos and AL DHneg cells were examined for the expression of stemness genes using reverse transcription-polymerase chain reaction (RT. PCR) array. Tumor cell-derived FA and sporadic HNSCC were examined for their ability to form tumorspheres in vitro. Stem-like cell population in FA and sporadic HNSCC in human and mouse xenograft tumors were evaluated using AL DH isoform 1 (AL DH1) immunohistochemistry. FA. HNSCC cell lines harbor a greater proportion of AL DHpos cells (15.31%) compared to sporadic HNSCC.(10%). Expression of Nanog, Oct.3/4 and Stella, molecular markers of undifferentiated embryonic stem (ES) cells were detected in the AL DHpos FA. HNSCC cells and not in the AL DHneg cells. FA. HNSCC cell lines revealed enhanced in vitro tumorsphere formation compared to sporadic HNSCC cells. A higher percentage of AL DH1pos tumor cells are noted in the human and mouse xenograft tumors of FA. HNSCC compared to sporadic HNSCC tumors. FA. HNSCC are highly enriched for CSC and may serve as a model to develop CSC. targeted therapies for HNSCC.