title: CD24(+) cells fuel rapid tumor growth and display high metastatic capacity.
abstract: BACKGROUND
  Breast tumors are comprised of distinct cancer cell populations which differ in their tumorigenic and metastatic capacity. Characterization of cell surface markers enables investigators to distinguish between cancer stem cells and their counterparts. CD24 is a well-known cell surface marker for mammary epithelial cells isolation, recently it was suggested as a potential prognostic marker in a wide variety of malignancies. Here, we demonstrate that CD24(+) cells create intra-tumor heterogeneity, and display highly metastatic properties.
  
  
  METHODS
  The mammary carcinoma Mvt1 cells were sorted into CD24(-) and CD24(+) cells. Both subsets were morphologically and phenotypically characterized, and tumorigenic capacity was assessed via orthotopic inoculation of each subset into the mammary fat pad of wild-type and MKR mice. The metastatic capacity of each subset was determined with the tail vein metastasis assay. The role of CD24 in tumorigenesis was further examined with shRNA technology. GFP-labeled cells were monitored in vivo for differentiation. The genetic profile of each subset was analyzed using RNA sequencing.
  
  
  RESULTS
  CD24(+) cells displayed a more spindle-like cytoplasm. The cells formed mammospheres in high efficiency and CD24(+) tumors displayed rapid growth in both WT and MKR mice, and were more metastatic than CD24- cells. Interestingly, CD24-KD in CD24+ cells had no effect both in vitro and in vivo on the various parameters studied. Moreover, CD24(+) cells gave rise in vivo to the CD24(-) that comprised the bulk of the tumor. RNA-seq analysis revealed enrichment of genes and pathways of the extracellular matrix in the CD24(+) cells.
  
  
  CONCLUSIONS
  CD24(+) cells account for heterogeneity in mammary tumors. CD24 expression at early stages of the cancer process is an indication of a highly invasive tumor. However, CD24 is not a suitable therapeutic target; instead we suggest here new potential targets accounting for early differentiated cancer cells tumorigenic capacity.
authors.affiliation: Diabetes and Metabolism Clinical Research Center of Excellence, Clinical Research Institute at Rambam (CRIR) and the Faculty of Medicine, Technion, Rambam Medical Center, P.O.B 9602, Haifa, 31096, Israel. ranrosto@gmail.com.
authors.forename: Ran
authors.initials: R
authors.lastname: Rostoker
authors.affiliation: Laboratory of Molecular Medicine, Rambam Health Care Campus and Rappaport Faculty of Medicine and Research Institute, Technion, Haifa, 31096, Israel. sagiab@tx.technion.ac.il.
authors.forename: Sagi
authors.initials: S
authors.lastname: Abelson
authors.affiliation: Diabetes and Metabolism Clinical Research Center of Excellence, Clinical Research Institute at Rambam (CRIR) and the Faculty of Medicine, Technion, Rambam Medical Center, P.O.B 9602, Haifa, 31096, Israel. inna.genkin@mail.utoronto.ca.
authors.forename: Inna
authors.initials: I
authors.lastname: Genkin
authors.affiliation: Diabetes and Metabolism Clinical Research Center of Excellence, Clinical Research Institute at Rambam (CRIR) and the Faculty of Medicine, Technion, Rambam Medical Center, P.O.B 9602, Haifa, 31096, Israel. saritbe9@gmail.com.
authors.forename: Sarit
authors.initials: S
authors.lastname: Ben-Shmuel
authors.affiliation: Department of Oncological Science, Icahn School of Medicine at Mt Sinai and the James J Peters VA Medical Center, New York, USA. ravi.sachidanandam@mssm.edu.
authors.forename: Ravi
authors.initials: R
authors.lastname: Sachidanandam
authors.affiliation: Diabetes and Metabolism Clinical Research Center of Excellence, Clinical Research Institute at Rambam (CRIR) and the Faculty of Medicine, Technion, Rambam Medical Center, P.O.B 9602, Haifa, 31096, Israel. eyal.scheinman@gmail.com.
authors.forename: Eyal J
authors.initials: EJ
authors.lastname: Scheinman
authors.affiliation: Diabetes and Metabolism Clinical Research Center of Excellence, Clinical Research Institute at Rambam (CRIR) and the Faculty of Medicine, Technion, Rambam Medical Center, P.O.B 9602, Haifa, 31096, Israel. kerenworms@gmail.com.
authors.forename: Keren
authors.initials: K
authors.lastname: Bitton-Worms
authors.affiliation: Diabetes and Metabolism Clinical Research Center of Excellence, Clinical Research Institute at Rambam (CRIR) and the Faculty of Medicine, Technion, Rambam Medical Center, P.O.B 9602, Haifa, 31096, Israel. z_shenorr@rambam.health.gov.il.
authors.forename: Zila Shen
authors.initials: ZS
authors.lastname: Orr
authors.affiliation: Diabetes and Metabolism Clinical Research Center of Excellence, Clinical Research Institute at Rambam (CRIR) and the Faculty of Medicine, Technion, Rambam Medical Center, P.O.B 9602, Haifa, 31096, Israel. avishaycaspi@walla.com.
authors.forename: Avishay
authors.initials: A
authors.lastname: Caspi
authors.affiliation: Laboratory of Molecular Medicine, Rambam Health Care Campus and Rappaport Faculty of Medicine and Research Institute, Technion, Haifa, 31096, Israel. bimaty@tx.technion.ac.il.
authors.forename: Maty
authors.initials: M
authors.lastname: Tzukerman
authors.affiliation: Diabetes and Metabolism Clinical Research Center of Excellence, Clinical Research Institute at Rambam (CRIR) and the Faculty of Medicine, Technion, Rambam Medical Center, P.O.B 9602, Haifa, 31096, Israel. derek.leroith@mssm.edu.|Division of Endocrinology, Diabetes and Bone Disease, Icahn School of Medicine at Mount Sinai, New York, NY, USA. derek.leroith@mssm.edu.
authors.forename: Derek
authors.initials: D
authors.lastname: LeRoith
mesh_terms: D000818:Animals; D015415:Biomarkers; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology*; D051927:CD24 Antigen / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002471:Cell Transformation, Neoplastic / Q000378:metabolism; D004195:Disease Models, Animal; D005109:Extracellular Matrix / Q000235:genetics / Q000378:metabolism; D005260:Female; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D055786:Gene Knockout Techniques; D016130:Immunophenotyping; D051379:Mice; D009362:Neoplasm Metastasis; D014411:Neoplastic Stem Cells / Q000378:metabolism; D010641:Phenotype; D047368:Tumor Burden
chemical_list: D015415:Biomarkers; D051927:CD24 Antigen