Biological Characteristics Of ALDH^hig Subpopulation In Tongue Squamous Cell Carcinoma Tca8113Cell Line

INTRODUCTIONIn recent years, there is a growing body of reseach that cancer stemcslls（CSCs） are the drving force of tumor formation in many cancersincluding cancers of human acute myeloid and lymphoidleukemialiver,colon,brain,pancreas and breast. Cancer stem cells areself-renewal and drive metastasis, recurrence, tumorigenicity, resistance ofradiotherapy and chemotherapy.They can differentiate into many othercancer cells which constitute the main body of the tumor.A lot of evidenceprove that only few tumor cells with stem cell characteristics can proliferateand differentiate the tumer.So the key of curing the tumor is curing theCSCs.How to sort for CSCs has become the focus of the reseach.Aldehyde dehydrogenase（ALDH） is a kind of human oxidaseisozymes,which can oxidate aldehyde to alcohols in cells. In recent years, itis report that ALDH can be helpful for identifying CSCs from primarytumor tissue and cell line. The expression of aldehyde dehydrogenas 1（ALDH1） in many cancers rise.ALDH is the useful maker of CSCs in manycancers including cancers of breast,liver,lung, prostate, pancreas,hematopoietic system,colon and squamous cell carcinoma of the head andneck（SCCHN）.So, cells expressing high level of ALDH(ALDH^hig)intongue squamous cell carcinoma Tca8113cell line may be with the stemcell characteristics.The purpose is to detect the expression of ALDH in tonguesquamous cell carcinoma Tca8113cell line and observe the biologicalcharacteristics of ALDH^higsubpopulation cells by detecting the ability ofdifferentiation, proliferation and tumorsphere formation of ALDH^higcells.PartⅠ ALDH^higsubpopulation cells detected in tonguesquamous cell carcinoma Tca8113cell lineObjective: To detect the expression of ALDH in tongue squamouscell carcinoma Tca8113cell line and identify ALDH^higcells from tonguesquamous cell carcinoma Tca8113cellMethods: The expression of ALDH in tongue squamous cellcarcinoma Tca8113cell line was detected by the flow cytometry. TheALDH^higand ALDHlowsubpopulation cells were isolated.Results: The ALDH^higcells in tongue squamous cell carcinomaTca8113cell line was rarely1.3%. Part Ⅱ The ability of differentiation, proliferation andtumorsphere formation of ALDH^higsubpopulation cellsObjective: To observe the ability of differentiation, proliferation andtumorsphere formation of the ALDH^higsubpopulation cells in tonguesquamous cell carcinoma Tca8113cell line.Methods: The ALDH^higand ALDHlowsubpopulation cells werecultured in vitro respectively. The ability of proliferation of theALDH^hig,ALDHlowand unsorted cells in serum supplement medium weredetermined by CCK-8assay. The expression of ALDH in the counterparts ofsorted ALDH^higcells were detected on the scheduled time（1.3.5.7day）. TheALDH^higand ALDHlowcells were planted and observed in serum-freemedium.Results: Compared with ALDHlowcells and unsorted cells, ALDH^higcells demonstrated increased proliferation capacity.After culture in vitro，thepercentage of ALDH^higcells decreased gradually to the level of that inunsorted tumor cells. The ALDH^higsubpopulation cells could survive inserum free medium and generate tumorspheres.Part Ⅲ Tumorigenicity of ALDH^higsubpopulation cells intongue squamous cell carcinoma of NOD/SCID MICEObjective: To assess the tumorigenic capacity of ALDH^higcells andunsorted cells in NOD/SCID mice. Methods: The tumorigenicity of ALDH^higcells and unsorted cells invivo were assessed by implanting them into NOD/SCID mice toconstituted animal model.Results:New tumor could form when103ALDH^higcells injected intothe Subcutaneous tissue of back of NOD/SCID mice. And more than105unsoted cells injected could form new tumor,too.Compare with unsortedcell, the tumors of ALDH^higcell were bigger when105cells injected.Conclusions: There was a rare subpopulation cells expressing ALDHhighly, which displayed characteristics similar to stem cells; ALDH may beone of makers for cancer stem cells of tongue squamous cell carcinomaTca8113cell line.