Carcinogenesis Advance Access originally published online on July 30, 2009
Carcinogenesis 2009 30(10):1678-1685; doi:10.1093/carcin/bgp189
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The human homolog of the Drosophila headcase protein slows down cell division of head and neck cancer cells
Department of Oral and Maxillofacial Surgery, University of Regensburg, Franz-Josef-Strauss-Allee 11, 93053 Regensburg, Germany
1 Department of Oral and Maxillofacial Plastic Surgery, University of Würzburg, Pleicherwall 2, 97070 Würzburg, Germany
* To whom correspondence should be addressed. Tel: +49 941 9446310; Fax: +49 941 944 6319; Email: albert.dowejko{at}klinik.uni-regensburg.de
The human homolog of the Drosophila headcase (HECA) belongs to a new class of cell differentiation regulators. In Drosophila, the HECA protein regulates the proliferation and differentiation of cells during adult morphogenesis. There is growing evidence that HECA plays an important role in human carcinogenesis. In different tumor entities, an altered HECA expression was found (colorectal, pancreatic and renal cancer). Colorectal cancer studies also suggested HECA as a marker for early disease stages. Therefore, we speculated whether human HECA affects cell cycle progression and proliferation in head and neck cancer cells. In vivo, we found a distinct HECA protein expression in basal and superficial cells of a healthy oral epithelium via immunohistochemistry, whereas in tissues of oral squamous cell carcinoma (OSCC), a weaker staining was observed, particularly in basal cells. In vitro, mRNA and protein expression analyses of OSCC cell lines exhibited that HECA expression correlates with the state of cellular differentiation. In further investigations, we overexpressed HECA in the OSCC cell line PCI 13 and performed functional assays. HECA-overexpressing OSCC cells revealed a significant extended doubling time (up to 45%, 17 h) and yielded a lower number of proliferating cells (up to 30%) than controls. Flow cytometry analyses have shown that HECA-overexpressing OSCC cells forced to hold in the G2/M-Phase. In summary, our results show that human HECA slows down cell division of OSCC cells and may therefore act as a tumor suppressor in head and neck cancer.
Abbreviations: cDNA, complementary DNA; HECA, headcase; HOK, human oral keratinocyte; IL, interleukin; NHEK, normal human keratinocyte; OSCC, oral squamous cell carcinoma; qPCR, quantitative real-time polymerase chain reaction
Received February 25, 2009; revised July 2, 2009; accepted July 25, 2009.