Chenling Shen1, Mingliang Xiang, Chen Nie, Haixia Hu, Yan Ma, Hao Wu. 1. Department of Otolaryngology & Head and Neck Surgery, The Ear Institute, Xinhua Hospital, Shanghai Jiao Tong University School of Medicine , Shanghai , China.
Abstract
CONCLUSIONS: The CD44(+) cells have a stronger proliferative capacity and higher tumorigenic potential than the CD44(-) cells, which suggests that the cancer stem cells of hypopharyngeal cancer may exist in the CD44(+) tumor cell population. Therefore, we propose that CD44 is an important biological marker to screen cancer stem cells of hypopharyngeal cancer. OBJECTIVES: To study the significance of CD44 as a molecular marker for screening cancer stem cells in hypopharyngeal cancer. METHODS: The CD44 expression levels in the hypopharyngeal cancer cell line FaDu were analyzed using flow cytometry. To investigate the biological significance of the CD44(+) population, we sorted the CD44(+) and CD44(-) cell populations by using magnetic-associated cell sorting (MACS) technology. After the separation, the purity of the CD44(+) cells was determined using flow cytometry. The MTT method was used to detect the different proliferation capabilities 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 × 10(6) and 1 × 10(5)) into the body of NOD/SCID mice. RESULTS: Some (21.1 ± 1.56)% of the hypopharyngeal cancer cell line FaDu cells expressed CD44. The CD44(+) population was efficiently sorted by MACS, and after separation, the purity of the CD44(+) cells was (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 × 10(6) CD44(+) cells developed tumors (8/8), half the mice injected with 1 × 10(6) CD44(-) cells developed tumors (4/8), 1 of the 8 mice injected with 1 × 10(5) CD44(+) cells developed tumors (12.5%), but none of the mice injected with 1 × 10(5) 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). Furthermore, the CD44(+) group had a shorter incubation period than the CD44(-) group. In addition, the average tumor volume of the CD44(+) group was (2017.81 ± 538.50) mm(3); however, the average tumor volume of the CD44(-) group was (1153.25 ± 503.18) mm(3). The difference was statistically significant (t = 2.67, p < 0.05).
CONCLUSIONS: The CD44(+) cells have a stronger proliferative capacity and higher tumorigenic potential than the CD44(-) cells, which suggests that the cancer stem cells of hypopharyngeal cancer may exist in the CD44(+) tumor cell population. Therefore, we propose that CD44 is an important biological marker to screen cancer stem cells of hypopharyngeal cancer. OBJECTIVES: To study the significance of CD44 as a molecular marker for screening cancer stem cells in hypopharyngeal cancer. METHODS: The CD44 expression levels in the hypopharyngeal cancer cell line FaDu were analyzed using flow cytometry. To investigate the biological significance of the CD44(+) population, we sorted the CD44(+) and CD44(-) cell populations by using magnetic-associated cell sorting (MACS) technology. After the separation, the purity of the CD44(+) cells was determined using flow cytometry. The MTT method was used to detect the different proliferation capabilities 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 × 10(6) and 1 × 10(5)) into the body of NOD/SCIDmice. RESULTS: Some (21.1 ± 1.56)% of the hypopharyngeal cancer cell line FaDu cells expressed CD44. The CD44(+) population was efficiently sorted by MACS, and after separation, the purity of the CD44(+) cells was (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 × 10(6) CD44(+) cells developed tumors (8/8), half the mice injected with 1 × 10(6) CD44(-) cells developed tumors (4/8), 1 of the 8 mice injected with 1 × 10(5) CD44(+) cells developed tumors (12.5%), but none of the mice injected with 1 × 10(5) 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). Furthermore, the CD44(+) group had a shorter incubation period than the CD44(-) group. In addition, the average tumor volume of the CD44(+) group was (2017.81 ± 538.50) mm(3); however, the average tumor volume of the CD44(-) group was (1153.25 ± 503.18) mm(3). The difference was statistically significant (t = 2.67, p < 0.05).