Clinical Implications of BMI-1 in Cancer Stem Cells of Laryngeal Carcinoma

Abstract

The objective of this study is to investigate the chemoresistance of CD133(+) cancer stem cells in Hep-2 cells of laryngeal cancer and detect the expression mRNA and protein levels of BMI-1 in CD133(+) cells and CD133(-) cells. The response of Hep-2 cells to different chemotherapeutic agents was investigated, and the expression of CD133 was studied. Fluorescence-activated cell sorting analysis was used to identify CD133, and the CD133(+) subset of cells was separated and analyzed chemotherapy resistance. Colony formation assays were studied and cells were injected subcutaneously into axillary fossa of node mice to measure the tumor-forming ability. RT-PCR and Western blot analyses were used to detect the expression levels of BMI-1 in the different subpopulation cells. It was concluded that chemotherapy enriched the CD133(+) subpopulation 2-fourfold, relative to the untreated cells. 1.55 ± 0.28% of Hep-2 cells were observed to be CD133(+) cells. Flow cytometric analysis revealed that after the treatment with these chemotherapeutic agents, the expression of CD133 was up to 5.16 ± 0.86%, 4.94 ± 0.58%, 3.66 ± 0.59%. After 5-FU treatment, the expression of CD133 was 6.7 ± 1.6% relative to the untreated mice 2.6 ± 0.96% by nude mice tumor xenograft model. CD133(+) cancer stem cells were more resistant to chemotherapy; the proliferation capability and tumor-forming ability were no difference after chemotherapy. Semi-quantitative RT-PCR and Western blot analyses provided strong evidence that BMI-1 expression in CD133(+) cells is different from CD133(-) cells remarkably. Taken together, it was confirmed that CD133(+) cancer stem cells were chemoresistant and BMI-1 was highly expressed in these CD133(+) cells.

Upregulation of the proto-oncogene Bmi-1 predicts a poor prognosis in pediatric acute lymphoblastic leukemia

“…Consistent with our results, research on ovarian cancer [35], breast cancer [36, 37], clear cell renal cancer [38], laryngeal carcinoma [39], cervical cancer [40], and esophageal adenocarcinoma [41] have reported an association between high Bmi-1 expression and an unfavorable prognosis. It has also been reported that high expression of Bmi-1 in AML cells is associated with an unfavorable prognosis [42].…”

Current cancer stem cell biomarkers in laryngeal cancer

“…They found that almost half of the cells were CD44+, which showed stronger proliferative capacity compared to CD44 negative (CD44-) cells. These findings pointed that CD44+ cells might be enriched for CSCs in laryngeal carcinoma samples [34].…”

“…It has been found to induce tumor invasion, metastasis and chemoresistance of solid tumors [53,54]. As an initial study, Yu et al [55] demonstrated significant overexpression of oncogenic BMI1 protein,which involves in gene silencing, through chromatin modifications [55], in CD44+/CD133+ cells [34]. It was reported to be upregulated in laryngeal tumor tissue samples and CD133 positive Hep-2 cells, which provided maintenance of cell proliferation and prevented apoptosis [52,56].…”

“…The potential of CD44 in terms of its implication in stem cell characteristics of human laryngeal carcinoma cells was initially evaluated by Yu et al [34] through isolation of CD44 positive (CD44+) cells from primary cultures of tumor samples obtained from 5 patients. They found that almost half of the cells were CD44+, which showed stronger proliferative capacity compared to CD44 negative (CD44-) cells.…”

Antiproliferative potential of miR‐33a in laryngeal cancer Hep‐2 cells via targeting PIM1

“…Laryngeal cancer, as a frequent cause of cancer‐associated mortality worldwide, is one of the most common malignancies in the head and neck region . Despite novel diagnostic and therapeutic modalities developed for larnygeal cancer in the last decades, the prognosis seems to remain poor along with high mortality rates .…”