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Exposure of tumor-associated macrophages to apoptotic MCF-7 cells promotes breast cancer growth and metastasis.

Zhou N, Zhang Y, Zhang X, Lei Z, Hu R, Li H, Mao Y, Wang X, Irwin DM, Niu G, Tan H - Int J Mol Sci (2015)

Bottom Line: Tumor-associated macrophages (TAMs) have been found to be associated with the progression and metastasis of breast cancer.Macrophages co-cultured with apoptotic MCF-7 had increased tumor growth and metastatic ability in a nude mouse transplantation assay.During this process, macrophages secreted increased amounts of interleukin 6 (IL-6) leading to increased phosphorylation of signal transducers and activators of transcription 3 (STAT3), which likely explains the increased transcription of STAT3 target genes such as TGF-β1 and HIF-1α.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, Peking University, Health Science Center, Beijing 100191, China. zhouna@bjmu.edu.cn.

ABSTRACT
Tumor-associated macrophages (TAMs) have been found to be associated with the progression and metastasis of breast cancer. To clarify the mechanisms underlying the crosstalk between TAMs and cancer stem cells (CSCs) in breast cancer recurrence and metastasis, we used a co-culture model of macrophages and apoptotic human breast cancer cell line MCF-7 cells to investigate the effects of TAMs on MCF-7 in vitro and in vivo. Macrophages co-cultured with apoptotic MCF-7 had increased tumor growth and metastatic ability in a nude mouse transplantation assay. The macrophages exposed to apoptotic cells also induce an increase in the proportion of CD44+/CD24- cancer stem-like cells, as well as their proliferative ability accompanied with an increase in mucin1 (MUC1) expression. During this process, macrophages secreted increased amounts of interleukin 6 (IL-6) leading to increased phosphorylation of signal transducers and activators of transcription 3 (STAT3), which likely explains the increased transcription of STAT3 target genes such as TGF-β1 and HIF-1α. Our results indicate that when cancer cells endure chemotherapy induced apoptosis, macrophages in their microenvironment can then activate cancer stem cells to promote cancer growth and metastasis by secreting IL-6, which activates STAT3 phosphorylation to regulate the transcription of its downstream target genes.

No MeSH data available.


Related in: MedlinePlus

Analysis of the proliferative abilities of sorted CD44+/CD24− and CD44+/CD24+ subpopulations of MCF-7 cells and Mucin1(MUC1) protein levels in MCF-7 cells cultured in four types of media. (A) 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay examining the proliferative ability of the CD44+/CD24− cells of the three groups. Results are typical of the three independent experiments. Data represent means ± S.E. (n = 3). ***p < 0.001 vs. the normal media group; (B) MTS assay examining the proliferative ability of the CD44+/CD24+ cells of the three groups. Results are typical of the three independent experiments. Data represent means ± S.E. (n = 3); (C) Western blot analysis of MUC1 levels. Band intensity was analyzed using Quantity One software and β-actin was used as a loading control. Protein levels were compared to the normal media group. Results are typical of three independent experiments. Data represent means ± S.E. (n = 3). *p < 0.05, vs. the Normal media group; #p < 0.05 vs. the Mac group; ns means no significance.
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ijms-16-11966-f003: Analysis of the proliferative abilities of sorted CD44+/CD24− and CD44+/CD24+ subpopulations of MCF-7 cells and Mucin1(MUC1) protein levels in MCF-7 cells cultured in four types of media. (A) 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay examining the proliferative ability of the CD44+/CD24− cells of the three groups. Results are typical of the three independent experiments. Data represent means ± S.E. (n = 3). ***p < 0.001 vs. the normal media group; (B) MTS assay examining the proliferative ability of the CD44+/CD24+ cells of the three groups. Results are typical of the three independent experiments. Data represent means ± S.E. (n = 3); (C) Western blot analysis of MUC1 levels. Band intensity was analyzed using Quantity One software and β-actin was used as a loading control. Protein levels were compared to the normal media group. Results are typical of three independent experiments. Data represent means ± S.E. (n = 3). *p < 0.05, vs. the Normal media group; #p < 0.05 vs. the Mac group; ns means no significance.

Mentions: The tumorigenicity of cancer cells depends on the proportion and activity of cancer stem cells. The proportion of cancer stem cells in the tumor depends on the proliferative ability of both the cancer stem cells and the non-stem cells. CD44+/CD24− cells have stem cell-like properties [19] and were used here as a marker of the cancer stem cell-like population. We sorted the CD44+/CD24− cells and CD44+/CD24+ from MCF-7 cells that had been cultured in the different types of conditioned media and their proliferative ability was examined using the MTS assay. Growth of these two subpopulations was measured for 72 h. The CD44+/CD24− cells from the CoA group displayed an increased proliferative rate, which was significantly more rapid at 48 and 72 h compared with the normal media group (Figure 3A). In contrast, the proliferative ability of the CD44+/CD24− subpopulation from the Mac group was significantly decreased at all time points, including 24 h (Figure 3A). The proliferation ability of the CD44+/CD24+ subpopulation showed no significant difference among the three groups at any time point (Figure 3B). These results parallel the in vivo experimental metastasis assay, where the CoA group has increased metastasis and the Mac group decreased ability compared with the normal media cell group (Figure 2E,H).


Exposure of tumor-associated macrophages to apoptotic MCF-7 cells promotes breast cancer growth and metastasis.

Zhou N, Zhang Y, Zhang X, Lei Z, Hu R, Li H, Mao Y, Wang X, Irwin DM, Niu G, Tan H - Int J Mol Sci (2015)

Analysis of the proliferative abilities of sorted CD44+/CD24− and CD44+/CD24+ subpopulations of MCF-7 cells and Mucin1(MUC1) protein levels in MCF-7 cells cultured in four types of media. (A) 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay examining the proliferative ability of the CD44+/CD24− cells of the three groups. Results are typical of the three independent experiments. Data represent means ± S.E. (n = 3). ***p < 0.001 vs. the normal media group; (B) MTS assay examining the proliferative ability of the CD44+/CD24+ cells of the three groups. Results are typical of the three independent experiments. Data represent means ± S.E. (n = 3); (C) Western blot analysis of MUC1 levels. Band intensity was analyzed using Quantity One software and β-actin was used as a loading control. Protein levels were compared to the normal media group. Results are typical of three independent experiments. Data represent means ± S.E. (n = 3). *p < 0.05, vs. the Normal media group; #p < 0.05 vs. the Mac group; ns means no significance.
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ijms-16-11966-f003: Analysis of the proliferative abilities of sorted CD44+/CD24− and CD44+/CD24+ subpopulations of MCF-7 cells and Mucin1(MUC1) protein levels in MCF-7 cells cultured in four types of media. (A) 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay examining the proliferative ability of the CD44+/CD24− cells of the three groups. Results are typical of the three independent experiments. Data represent means ± S.E. (n = 3). ***p < 0.001 vs. the normal media group; (B) MTS assay examining the proliferative ability of the CD44+/CD24+ cells of the three groups. Results are typical of the three independent experiments. Data represent means ± S.E. (n = 3); (C) Western blot analysis of MUC1 levels. Band intensity was analyzed using Quantity One software and β-actin was used as a loading control. Protein levels were compared to the normal media group. Results are typical of three independent experiments. Data represent means ± S.E. (n = 3). *p < 0.05, vs. the Normal media group; #p < 0.05 vs. the Mac group; ns means no significance.
Mentions: The tumorigenicity of cancer cells depends on the proportion and activity of cancer stem cells. The proportion of cancer stem cells in the tumor depends on the proliferative ability of both the cancer stem cells and the non-stem cells. CD44+/CD24− cells have stem cell-like properties [19] and were used here as a marker of the cancer stem cell-like population. We sorted the CD44+/CD24− cells and CD44+/CD24+ from MCF-7 cells that had been cultured in the different types of conditioned media and their proliferative ability was examined using the MTS assay. Growth of these two subpopulations was measured for 72 h. The CD44+/CD24− cells from the CoA group displayed an increased proliferative rate, which was significantly more rapid at 48 and 72 h compared with the normal media group (Figure 3A). In contrast, the proliferative ability of the CD44+/CD24− subpopulation from the Mac group was significantly decreased at all time points, including 24 h (Figure 3A). The proliferation ability of the CD44+/CD24+ subpopulation showed no significant difference among the three groups at any time point (Figure 3B). These results parallel the in vivo experimental metastasis assay, where the CoA group has increased metastasis and the Mac group decreased ability compared with the normal media cell group (Figure 2E,H).

Bottom Line: Tumor-associated macrophages (TAMs) have been found to be associated with the progression and metastasis of breast cancer.Macrophages co-cultured with apoptotic MCF-7 had increased tumor growth and metastatic ability in a nude mouse transplantation assay.During this process, macrophages secreted increased amounts of interleukin 6 (IL-6) leading to increased phosphorylation of signal transducers and activators of transcription 3 (STAT3), which likely explains the increased transcription of STAT3 target genes such as TGF-β1 and HIF-1α.

View Article: PubMed Central - PubMed

Affiliation: Department of Pharmacology, Peking University, Health Science Center, Beijing 100191, China. zhouna@bjmu.edu.cn.

ABSTRACT
Tumor-associated macrophages (TAMs) have been found to be associated with the progression and metastasis of breast cancer. To clarify the mechanisms underlying the crosstalk between TAMs and cancer stem cells (CSCs) in breast cancer recurrence and metastasis, we used a co-culture model of macrophages and apoptotic human breast cancer cell line MCF-7 cells to investigate the effects of TAMs on MCF-7 in vitro and in vivo. Macrophages co-cultured with apoptotic MCF-7 had increased tumor growth and metastatic ability in a nude mouse transplantation assay. The macrophages exposed to apoptotic cells also induce an increase in the proportion of CD44+/CD24- cancer stem-like cells, as well as their proliferative ability accompanied with an increase in mucin1 (MUC1) expression. During this process, macrophages secreted increased amounts of interleukin 6 (IL-6) leading to increased phosphorylation of signal transducers and activators of transcription 3 (STAT3), which likely explains the increased transcription of STAT3 target genes such as TGF-β1 and HIF-1α. Our results indicate that when cancer cells endure chemotherapy induced apoptosis, macrophages in their microenvironment can then activate cancer stem cells to promote cancer growth and metastasis by secreting IL-6, which activates STAT3 phosphorylation to regulate the transcription of its downstream target genes.

No MeSH data available.


Related in: MedlinePlus