Absence of primary cilia in cell cycle‐arrested human breast cancer cells

Abstract

Previous studies using cultured cells showed that primary cilia are present in quiescent cells, but are absent in proliferating cells. We studied here the relationship between the presence or absence of primary cilia and the cell cycle arrest of normal epithelial cells and cancer cells in the human normal breast and breast cancer tissues. In normal breast tissues, although most epithelial cells were nonproliferating as estimated by the immunofluorescence staining of the proliferation marker Ki-67, primary cilia were present only in 20-40% of the epithelial cells. In breast cancer tissues, primary cilia were not observed in any of the breast cancer cells. Furthermore, primary cilia were hardly observed in the nonproliferating cancer cells in the orthotopic and metastatic human breast cancer xenograft tumors in mice. These results indicate that the absence of primary cilia does not necessarily represent the proliferating phases of normal epithelial cells and cancer cells.

Downregulation of CXCR4 in Metastasized Breast Cancer Cells and Implication in Their Dormancy

“…To examine the characteristics of dormant breast cancer cells, we analyzed xenograft tumors in mice that we generated by orthotopic xenotransplantation of human breast cancer tissues obtained from breast cancer patients and the human breast cancer cell line MDA-MB-231 [9]. In the following experiments, we used one of the PDX lines and one from the cell line that allowed us to detect and isolate the cancer cells by the green fluorescence protein ZsGreen1 that was transduced to the cell line or the expression of the HLA-A, B, C (Figs 1, 3, 4 and 5; S1, S2 and S3 Figs).…”

“…In the following experiments, we used one of the PDX lines and one from the cell line that allowed us to detect and isolate the cancer cells by the green fluorescence protein ZsGreen1 that was transduced to the cell line or the expression of the HLA-A, B, C (Figs 1, 3, 4 and 5; S1, S2 and S3 Figs). The human breast cancer PDX was generated from the ER (+)/PR (+)/HER2 (-) breast cancer and the MDA-MB-231 cells showed triple-negative breast cancer phenotype [9,22]. The growth rate of the PDX was much lower than that of the cell line-derived xenografts: the PDX and cell line-derived xenografts reached approximately 1–2 cm in about 3 months and 5–6 weeks, respectively.…”

“…The tissues were minced and suspended in Matrigel (BD Biosciences), and then transplanted into the inguinal mammary fat pad regions of NOD-SCID mice as previously described [19]. Four patient-derived xenograft (PDX) lines were established with this method as previously reported [9]. In the generation of the cell line-derived xenograft tumor, MDA-MB-231 cells were infected with a lentivirus vector encoding ZsGreen1 (Clontech), and ZsGreen1-expressing cells were sorted by FACS Aria I (BD Biosciences) and cultured in DMEM supplemented with 10% FBS, 100 U/ml penicillin, and 100 μg/ml streptomycin at 5% CO 2 at 37°C.…”

“…We recently generated breast cancer tumor models in mice by orthotopic xenotransplantation of human breast cancer tissues obtained from breast cancer patients and the human breast cancer cell line MDA-MB-231 [8,9]. Using these models, we analyzed the relationship between cell proliferation and the presence of primary cilia in cancer cells using the cell proliferation marker Ki-67 [9].…”

“…Using these models, we analyzed the relationship between cell proliferation and the presence of primary cilia in cancer cells using the cell proliferation marker Ki-67 [9]. Cancer cells in these models showed heterogeneity in terms of proliferating activity, and Ki-67-positive proliferating cancer cells were dominant in the orthotopic tumor.…”