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Leptin produced by obese adipose stromal/stem cells enhances proliferation and metastasis of estrogen receptor positive breast cancers.

Strong AL, Ohlstein JF, Biagas BA, Rhodes LV, Pei DT, Tucker HA, Llamas C, Bowles AC, Dutreil MF, Zhang S, Gimble JM, Burow ME, Bunnell BA - Breast Cancer Res. (2015)

Bottom Line: BCCs co-cultured with obASCs demonstrated enhanced expression of epithelial-to-mesenchymal transition (EMT) and metastasis genes (SERPINE1, MMP-2, and IL-6), while BCCs co-cultured with leptin shRNA obASCs did not display similar levels of gene induction.Knockdown of leptin significantly reduced tumor volume and decreased the number of metastatic lesions to the lung and liver.These results correlated with reduced expression of both SERPINE1 and MMP-2 in tumors formed with MCF7 cells mixed with leptin shRNA obASCs, when compared to tumors formed with MCF7 cells mixed with control shRNA obASCs.

View Article: PubMed Central - PubMed

Affiliation: Center for Stem Cell Research and Regenerative Medicine, Tulane University School of Medicine, 1430 Tulane Avenue, SL-99, New Orleans, LA, 70112, USA. alin1@tulane.edu.

ABSTRACT

Introduction: The steady increase in the incidence of obesity among adults has been paralleled with higher levels of obesity-associated breast cancer. While recent studies have suggested that adipose stromal/stem cells (ASCs) isolated from obese women enhance tumorigenicity, the mechanism(s) by which this occurs remains undefined. Evidence suggests that increased adiposity results in increased leptin secretion from adipose tissue, which has been shown to increased cancer cell proliferation. Previously, our group demonstrated that ASCs isolated from obese women (obASCs) also express higher levels of leptin relative to ASCs isolated from lean women (lnASCs) and that this obASC-derived leptin may account for enhanced breast cancer cell growth. The current study investigates the impact of inhibiting leptin expression in lnASCs and obASCs on breast cancer cell (BCC) growth and progression.

Methods: Estrogen receptor positive (ER+) BCCs were co-cultured with leptin shRNA lnASCs or leptin shRNA obASCs and changes in the proliferation, migration, invasion, and gene expression of BCCs were investigated. To assess the direct impact of leptin inhibition in obASCs on BCC proliferation, MCF7 cells were injected alone or mixed with control shRNA obASCs or leptin shRNA obASCs into SCID/beige mice.

Results: ER+ BCCs were responsive to obASCs during direct co-culture, whereas lnASCs were unable to increase ER(+) BCC growth. shRNA silencing of leptin in obASCs negated the enhanced proliferative effects of obASC on BCCs following direct co-culture. BCCs co-cultured with obASCs demonstrated enhanced expression of epithelial-to-mesenchymal transition (EMT) and metastasis genes (SERPINE1, MMP-2, and IL-6), while BCCs co-cultured with leptin shRNA obASCs did not display similar levels of gene induction. Knockdown of leptin significantly reduced tumor volume and decreased the number of metastatic lesions to the lung and liver. These results correlated with reduced expression of both SERPINE1 and MMP-2 in tumors formed with MCF7 cells mixed with leptin shRNA obASCs, when compared to tumors formed with MCF7 cells mixed with control shRNA obASCs.

Conclusion: This study provides mechanistic insight as to how obesity enhances the proliferation and metastasis of breast cancer cells; specifically, obASC-derived leptin contributes to the aggressiveness of breast cancer in obese women.

No MeSH data available.


Related in: MedlinePlus

Leptin is essential for the adipose stromal/stem cells isolated from obese women (obASC)-driven metastasis MCF7 cells in vivo. a MCF7 cells were prepared alone or co-injected with adipose stromal/stem cells isolated from lean women (lnASCs) or obASCs (1:1 ratio) or c, co-injected with control short hairpin RNA (control shRNA) obASCs or leptin shRNA obASCs into the mammary fat pad of SCID/beige mice (n = 5 mice/group). Primary tumors were allowed to expand for 36 days, and the lung and liver were harvested for histological analysis of metastasis. Metastasis index was determined by the percentage of the liver and lung occupied by metastatic lesions. b, d Representative images of liver and lung sections. Liver sections were visualized at × 40 magnification and lung sections were visualized at × 10 and × 40 magnification (inset). Scale bars represent 50 μm. Bar represents ± standard error of the mean. ***P <0.0001 relative to MCF7 xenografts; ###P <0.0001 for comparison between MCF7 plus lnASC xenografts and MCF7 plus obASC xenografts; ΦΦΦP <0.0001 for comparison between MCF7 plus control shRNA obASC xenografts and MCF7 plus leptin shRNA obASC xenografts. Arrows highlight metastatic lesions within the liver or lung
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Fig7: Leptin is essential for the adipose stromal/stem cells isolated from obese women (obASC)-driven metastasis MCF7 cells in vivo. a MCF7 cells were prepared alone or co-injected with adipose stromal/stem cells isolated from lean women (lnASCs) or obASCs (1:1 ratio) or c, co-injected with control short hairpin RNA (control shRNA) obASCs or leptin shRNA obASCs into the mammary fat pad of SCID/beige mice (n = 5 mice/group). Primary tumors were allowed to expand for 36 days, and the lung and liver were harvested for histological analysis of metastasis. Metastasis index was determined by the percentage of the liver and lung occupied by metastatic lesions. b, d Representative images of liver and lung sections. Liver sections were visualized at × 40 magnification and lung sections were visualized at × 10 and × 40 magnification (inset). Scale bars represent 50 μm. Bar represents ± standard error of the mean. ***P <0.0001 relative to MCF7 xenografts; ###P <0.0001 for comparison between MCF7 plus lnASC xenografts and MCF7 plus obASC xenografts; ΦΦΦP <0.0001 for comparison between MCF7 plus control shRNA obASC xenografts and MCF7 plus leptin shRNA obASC xenografts. Arrows highlight metastatic lesions within the liver or lung

Mentions: As obASCs enhance the expression of EMT and metastatic genes in vitro, the role obASCs play in EMT and metastasis of BCCs was assessed in vivo. Immunocompromised mice were implanted with MCF7 cells alone, MCF7 cells mixed with lnASCs, or with obASCs for 36 days. Metastatic lesions in the lung and liver were visualized by H&E staining and quantified. Mice implanted with MCF7 cells alone had no metastatic lesions, whereas mice injected with MCF7 cells mixed with lnASCs (0.8 ± 0.07 %) and mice injected with MCF7 cells mixed with obASCs (2.0 ± 0.09 %) had significantly greater numbers of metastatic lesions (P <0.05; Fig. 7a-b; Additional file 7). These results indicate that while both lnASCs and obASCs enhanced metastasis of MCF7 cells, obASCs induced metastasis to the lung and liver more efficiently compared to lnASCs.Fig. 7


Leptin produced by obese adipose stromal/stem cells enhances proliferation and metastasis of estrogen receptor positive breast cancers.

Strong AL, Ohlstein JF, Biagas BA, Rhodes LV, Pei DT, Tucker HA, Llamas C, Bowles AC, Dutreil MF, Zhang S, Gimble JM, Burow ME, Bunnell BA - Breast Cancer Res. (2015)

Leptin is essential for the adipose stromal/stem cells isolated from obese women (obASC)-driven metastasis MCF7 cells in vivo. a MCF7 cells were prepared alone or co-injected with adipose stromal/stem cells isolated from lean women (lnASCs) or obASCs (1:1 ratio) or c, co-injected with control short hairpin RNA (control shRNA) obASCs or leptin shRNA obASCs into the mammary fat pad of SCID/beige mice (n = 5 mice/group). Primary tumors were allowed to expand for 36 days, and the lung and liver were harvested for histological analysis of metastasis. Metastasis index was determined by the percentage of the liver and lung occupied by metastatic lesions. b, d Representative images of liver and lung sections. Liver sections were visualized at × 40 magnification and lung sections were visualized at × 10 and × 40 magnification (inset). Scale bars represent 50 μm. Bar represents ± standard error of the mean. ***P <0.0001 relative to MCF7 xenografts; ###P <0.0001 for comparison between MCF7 plus lnASC xenografts and MCF7 plus obASC xenografts; ΦΦΦP <0.0001 for comparison between MCF7 plus control shRNA obASC xenografts and MCF7 plus leptin shRNA obASC xenografts. Arrows highlight metastatic lesions within the liver or lung
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Fig7: Leptin is essential for the adipose stromal/stem cells isolated from obese women (obASC)-driven metastasis MCF7 cells in vivo. a MCF7 cells were prepared alone or co-injected with adipose stromal/stem cells isolated from lean women (lnASCs) or obASCs (1:1 ratio) or c, co-injected with control short hairpin RNA (control shRNA) obASCs or leptin shRNA obASCs into the mammary fat pad of SCID/beige mice (n = 5 mice/group). Primary tumors were allowed to expand for 36 days, and the lung and liver were harvested for histological analysis of metastasis. Metastasis index was determined by the percentage of the liver and lung occupied by metastatic lesions. b, d Representative images of liver and lung sections. Liver sections were visualized at × 40 magnification and lung sections were visualized at × 10 and × 40 magnification (inset). Scale bars represent 50 μm. Bar represents ± standard error of the mean. ***P <0.0001 relative to MCF7 xenografts; ###P <0.0001 for comparison between MCF7 plus lnASC xenografts and MCF7 plus obASC xenografts; ΦΦΦP <0.0001 for comparison between MCF7 plus control shRNA obASC xenografts and MCF7 plus leptin shRNA obASC xenografts. Arrows highlight metastatic lesions within the liver or lung
Mentions: As obASCs enhance the expression of EMT and metastatic genes in vitro, the role obASCs play in EMT and metastasis of BCCs was assessed in vivo. Immunocompromised mice were implanted with MCF7 cells alone, MCF7 cells mixed with lnASCs, or with obASCs for 36 days. Metastatic lesions in the lung and liver were visualized by H&E staining and quantified. Mice implanted with MCF7 cells alone had no metastatic lesions, whereas mice injected with MCF7 cells mixed with lnASCs (0.8 ± 0.07 %) and mice injected with MCF7 cells mixed with obASCs (2.0 ± 0.09 %) had significantly greater numbers of metastatic lesions (P <0.05; Fig. 7a-b; Additional file 7). These results indicate that while both lnASCs and obASCs enhanced metastasis of MCF7 cells, obASCs induced metastasis to the lung and liver more efficiently compared to lnASCs.Fig. 7

Bottom Line: BCCs co-cultured with obASCs demonstrated enhanced expression of epithelial-to-mesenchymal transition (EMT) and metastasis genes (SERPINE1, MMP-2, and IL-6), while BCCs co-cultured with leptin shRNA obASCs did not display similar levels of gene induction.Knockdown of leptin significantly reduced tumor volume and decreased the number of metastatic lesions to the lung and liver.These results correlated with reduced expression of both SERPINE1 and MMP-2 in tumors formed with MCF7 cells mixed with leptin shRNA obASCs, when compared to tumors formed with MCF7 cells mixed with control shRNA obASCs.

View Article: PubMed Central - PubMed

Affiliation: Center for Stem Cell Research and Regenerative Medicine, Tulane University School of Medicine, 1430 Tulane Avenue, SL-99, New Orleans, LA, 70112, USA. alin1@tulane.edu.

ABSTRACT

Introduction: The steady increase in the incidence of obesity among adults has been paralleled with higher levels of obesity-associated breast cancer. While recent studies have suggested that adipose stromal/stem cells (ASCs) isolated from obese women enhance tumorigenicity, the mechanism(s) by which this occurs remains undefined. Evidence suggests that increased adiposity results in increased leptin secretion from adipose tissue, which has been shown to increased cancer cell proliferation. Previously, our group demonstrated that ASCs isolated from obese women (obASCs) also express higher levels of leptin relative to ASCs isolated from lean women (lnASCs) and that this obASC-derived leptin may account for enhanced breast cancer cell growth. The current study investigates the impact of inhibiting leptin expression in lnASCs and obASCs on breast cancer cell (BCC) growth and progression.

Methods: Estrogen receptor positive (ER+) BCCs were co-cultured with leptin shRNA lnASCs or leptin shRNA obASCs and changes in the proliferation, migration, invasion, and gene expression of BCCs were investigated. To assess the direct impact of leptin inhibition in obASCs on BCC proliferation, MCF7 cells were injected alone or mixed with control shRNA obASCs or leptin shRNA obASCs into SCID/beige mice.

Results: ER+ BCCs were responsive to obASCs during direct co-culture, whereas lnASCs were unable to increase ER(+) BCC growth. shRNA silencing of leptin in obASCs negated the enhanced proliferative effects of obASC on BCCs following direct co-culture. BCCs co-cultured with obASCs demonstrated enhanced expression of epithelial-to-mesenchymal transition (EMT) and metastasis genes (SERPINE1, MMP-2, and IL-6), while BCCs co-cultured with leptin shRNA obASCs did not display similar levels of gene induction. Knockdown of leptin significantly reduced tumor volume and decreased the number of metastatic lesions to the lung and liver. These results correlated with reduced expression of both SERPINE1 and MMP-2 in tumors formed with MCF7 cells mixed with leptin shRNA obASCs, when compared to tumors formed with MCF7 cells mixed with control shRNA obASCs.

Conclusion: This study provides mechanistic insight as to how obesity enhances the proliferation and metastasis of breast cancer cells; specifically, obASC-derived leptin contributes to the aggressiveness of breast cancer in obese women.

No MeSH data available.


Related in: MedlinePlus