title: Hyperactivation of mammalian target of rapamycin complex 1 (mTORC1) promotes breast cancer progression through enhancing glucose starvation-induced autophagy and Akt signaling.
abstract: The mammalian target of rapamycin complex 1 (mTORC1) is a master regulator of cell growth and proliferation. Recent studies have suggested that constitutive activation of mTORC1 in normal cells could lead to malignant tumor development in several tissues. However, the mechanisms of mTORC1 hyperactivation to promote the growth and metastasis of breast or other cancers are still not well characterized. Here, using a new inducible deletion system, we show that deletion of Tsc1 in mouse primary mammary tumor cells, either before or after their transplantation, significantly increased their growth in vivo. The increase in tumor growth was completely rescued by rapamycin treatment, suggesting a major contribution from mTORC1 hyperactivation. Interestingly, glucose starvation-induced autophagy, but not amino acid starvation-induced autophagy, was increased significantly in Tsc1-null tumor cells. Further analysis of these cells also showed an increased Akt activation but no significant changes in Erk signaling. Together, these results provide insights into the mechanism by which hyperactivation of mTORC1 promotes breast cancer progression through increasing autophagy and Akt activation in vivo.
authors.affiliation: From the Divisions of Molecular Medicine and Genetics, Department of Internal Medicine, and.
authors.forename: Yongqiang
authors.initials: Y
authors.lastname: Chen
authors.forename: Huijun
authors.initials: H
authors.lastname: Wei
authors.forename: Fei
authors.initials: F
authors.lastname: Liu
authors.forename: Jun-Lin
authors.initials: JL
authors.lastname: Guan
mesh_terms: D000818:Animals; D001343:Autophagy / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D002470:Cell Survival / Q000235:genetics; D005260:Female; D005947:Glucose / Q000172:deficiency* / Q000494:pharmacology; D057809:HEK293 Cells; D006801:Humans; D015151:Immunoblotting; D008325:Mammary Neoplasms, Experimental / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000076222:Mechanistic Target of Rapamycin Complex 1; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008819:Mice, Nude; D008822:Mice, Transgenic; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D009362:Neoplasm Metastasis; D051057:Proto-Oncogene Proteins c-akt / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D058570:TOR Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D000077004:Tuberous Sclerosis Complex 1 Protein; D047368:Tumor Burden / Q000235:genetics; D014407:Tumor Cells, Cultured; D025521:Tumor Suppressor Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D046912:Multiprotein Complexes; C000624650:TSC1 protein, human; C000624651:Tsc1 protein, mouse; D000077004:Tuberous Sclerosis Complex 1 Protein; D025521:Tumor Suppressor Proteins; D000076222:Mechanistic Target of Rapamycin Complex 1; D051057:Proto-Oncogene Proteins c-akt; D058570:TOR Serine-Threonine Kinases; D005947:Glucose
keywords: Autophagy; Breast Cancer; Mouse; Signaling; mTOR Complex (mTORC)