Abstract:ObjectiveTo study the significance of CD44 as a molecular marker for screening tumor stem cells in hypopharyngeal carcinoma.MethodsThe CD44 expression levels in the hypopharyngeal carcinoma cell line FaDu were analyzed using flow cytometry. The CD44+ and CD44cell populations were sorted by using magneticassociated cell sorting (MACS) technology. After separation, the purity of the CD44+ cells was detected using flow cytometry. The MTT method was used to detect the different proliferation capability of the CD44+ and CD44cells in vitro. The tumorigenicity of the CD44+ and CD44cells was determined by injecting CD44+ or CD44cells (1×106 and 1×105) into the body of NOD/SCID mice.ResultsCD44 expressed in (21.1±1.56)% of the FaDu cells. The CD44+ population was efficiently sorted by MACS with the purity of (99.4±0.29)％. The MTT assay indicated that the sorted CD44+ cells had a stronger proliferative capacity than the CD44cells. The tumorigenicity study showed that all the mice injected with 1×106 CD44+ cells developed tumors (8/8), half of the mice injected with 1×106 CD44cells developed tumors (4/8), 1 of the 8 mice injected with 1×105 CD44+ cells developed tumors (12.5%), but none of the mice injected with 1×105 CD44cells developed any tumors (0/8). At the same concentration, the difference in tumorigenic rates between the CD44+ and CD44groups was statistically significant (Fisher’s exact test, P< 0.05). In addition, the CD44+ group had a shorter incubation period than the CD44group. Furthermore, the average tumor volume of the CD44+ group was (2017.81±538.50) mm3, while that of the CD44group was (1153.25±503.18) mm3, and the difference was statistically significant (t=2.67, P<0.05).ConclusionsThe CD44+ cells have stronger proliferative capacity and higher tumorigenic potential than the CD44cells, which suggests that the tumor stem cells of hypopharyngeal carcinoma may exist in the CD44+ tumor cell population. Therefore,CD44 maybe an important biological marker for screening of tumor stem cells in hypopharyngeal carcinoma.