title: Leptin deficiency suppresses MMTV-Wnt-1 mammary tumor growth in obese mice and abrogates tumor initiating cell survival.
abstract: Obesity increases both the risk and mortality associated with many types of cancer including that of the breast. In mice, obesity increases both incidence of spontaneous tumors and burden of transplanted tumors. Our findings identify leptin, an adipose secreted cytokine, in promoting increased mammary tumor burden in obese mice and provide a link between this adipokine and cancer. Using a transplantable tumor that develops spontaneously in the murine mammary tumor virus-Wnt-1 transgenic mice, we show that tumors transplanted into obese leptin receptor (LepRb)-deficient (db/db) mice grow to eight times the volume of tumors transplanted into lean wild-type (WT) mice. However, tumor outgrowth and overall tumor burden is reduced in obese, leptin-deficient (ob/ob) mice. The residual tumors in ob/ob mice contain fewer undifferentiated tumor cells (keratin 6 immunopositive) compared with WT or db/db mice. Furthermore, tumors in ob/ob mice contain fewer cells expressing phosphorylated Akt, a growth promoting kinase activated by the LepRb, compared with WT and db/db mice. In vivo limiting dilution analysis of residual tumors from ob/ob mice indicated reduced tumor initiating activity suggesting fewer cancer stem cells (CSCs). The tumor cell populations reduced by leptin deficiency were identified by fluorescence-activated cell sorting and found to express LepRb. Finally, LepRb expressing tumor cells exhibit stem cell characteristics based on the ability to form tumorspheres in vitro and leptin promotes their survival. These studies provide critical new insight on the role of leptin in tumor growth and implicate LepRb as a CSC target.
authors.affiliation: Department of Cell Biology, Lerner Research Institute, Cleveland Clinic Foundation, 9500 Euclid Avenue, NC10, Cleveland, Ohio 44195, USA.
authors.forename: Qiao
authors.initials: Q
authors.lastname: Zheng
authors.forename: Sarah M
authors.initials: SM
authors.lastname: Dunlap
authors.forename: Jinling
authors.initials: J
authors.lastname: Zhu
authors.forename: Erinn
authors.initials: E
authors.lastname: Downs-Kelly
authors.forename: Jeremy
authors.initials: J
authors.lastname: Rich
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Hursting
authors.forename: Nathan A
authors.initials: NA
authors.lastname: Berger
authors.forename: Ofer
authors.initials: O
authors.lastname: Reizes
mesh_terms: D000818:Animals; D002277:Carcinoma / Q000150:complications / Q000235:genetics / Q000473:pathology*; D049109:Cell Proliferation; D002470:Cell Survival / Q000235:genetics; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000473:pathology; D015536:Down-Regulation / Q000502:physiology; D005260:Female; D020738:Leptin / Q000172:deficiency* / Q000235:genetics / Q000502:physiology; D015674:Mammary Neoplasms, Animal / Q000150:complications / Q000235:genetics / Q000473:pathology*; D008324:Mammary Tumor Virus, Mouse / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D008822:Mice, Transgenic; D014411:Neoplastic Stem Cells / Q000378:metabolism / Q000473:pathology / Q000502:physiology*; D009765:Obesity / Q000150:complications / Q000235:genetics; D054411:Receptors, Leptin / Q000235:genetics / Q000502:physiology; D051155:Wnt1 Protein / Q000235:genetics*
chemical_list: D020738:Leptin; D054411:Receptors, Leptin; D051155:Wnt1 Protein; C495246:Wnt1 protein, mouse; C515447:leptin receptor, mouse