title: Transfer of malignant trait to BRCA1 deficient human fibroblasts following exposure to serum of cancer patients.
abstract: BACKGROUND
  It was reported that metastases might occur via transfer of biologically active blood circulating molecules from the primary tumor to distant organs rather than only migration of cancer cells. We showed in an earlier study that exposure of immortalized human embryonic kidney cells (HEK 293) to cancer patient sera, induce their transformation into undifferentiated cancers due to a horizontal transfer of malignant traits. In the present work, we tested the hypothesis that even other human cells as long as they are deficient for a single oncosuppressor gene might undergo malignant transformation when exposed to human cancer serum.
  
  
  METHODS
  We used the CRISPR/Cas9 system to establish a stable BRCA1 knockout (KO) in human fibroblasts. The BRCA1-KO fibroblasts were exposed to cancer patients' sera or healthy patients' sera for 2 weeks. Treated cells were analyzed for cell proliferation and transformation to study their susceptibility to the oncogenic potential of cancer patients' sera and to determine the possible mechanisms underlying their hypothesized transformation.
  
  
  RESULTS
  BRCA1-KO fibroblasts treated with cancer patients' sera displayed higher proliferation and underwent malignant transformation as opposed to wild type control fibroblasts, which were not affected by exposure to cancer patients' sera. The malignant transformation was not seen when BRCA1-KO fibroblasts were treated with healthy human sera. Histological analysis of tumors generated by BRCA1-KO fibroblasts showed that they were carcinomas with phenotypical characteristics related to the cancers of the blood donor patients. Interestingly, BRCA1-KO fibroblasts were significantly more prone to internalize serum-derived exosomes, when compared to wild type fibroblasts. This suggests that oncosuppressor genes might protect the integrity of the cell genome also by blocking integration of cancer-derived exosomes.
  
  
  CONCLUSIONS
  These data support the hypothesis that any human cells carrying a single oncosuppressor mutation is capable of integrating cancer factors carried in the blood and undergo complete malignant transformation. Oncosuppressor genes might protect the cell genome by impeding the integration inside the cells of these mutating factors.
authors.affiliation: Cancer Research Program, McGill University Health Centre-Research Institute, 1001 Decarie Boulevard, Montreal, H4A 3J1, QC, Canada.|Department of Experimental Surgery, Faculty of Medicine, McGill University, 845 Rue Sherbrooke O, Montreal, H3A 0G4, QC, Canada.
authors.forename: Dana
authors.initials: D
authors.lastname: Hamam
authors.affiliation: Cancer Research Program, McGill University Health Centre-Research Institute, 1001 Decarie Boulevard, Montreal, H4A 3J1, QC, Canada.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Abdouh
authors.affiliation: Department of Pathology, McGill University Health Centre-Research Institute, 1001 Decarie Boulevard, H4A 3J1, Montreal, QC, Canada.
authors.forename: Zu-Hua
authors.initials: ZH
authors.lastname: Gao
authors.affiliation: Department of Obstetrics and Gynecology, Santo Bambino Hospital, via Torre del Vescovo 4, Catania, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Arena
authors.affiliation: Department of Surgical Sciences, Organ Transplantation and Advances Technologies, University of Catania, via Santa Sofia 84, Catania, Italy.
authors.forename: Manuel
authors.initials: M
authors.lastname: Arena
authors.affiliation: Cancer Research Program, McGill University Health Centre-Research Institute, 1001 Decarie Boulevard, Montreal, H4A 3J1, QC, Canada. goffredo.arena@mcgill.ca.|Department of Surgery, McGill University, St. Mary Hospital, 3830 Lacombe Avenue, Montreal, H3T 1M5, QC, Canada. goffredo.arena@mcgill.ca.
authors.forename: Goffredo Orazio
authors.initials: GO
authors.lastname: Arena
mesh_terms: D000328:Adult; D000368:Aged; D000818:Animals; D019313:BRCA1 Protein / Q000235:genetics*; D049109:Cell Proliferation; D002471:Cell Transformation, Neoplastic / Q000235:genetics*; D017077:Culture Media, Conditioned / Q000494:pharmacology*; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects* / Q000473:pathology; D055786:Gene Knockout Techniques; D057809:HEK293 Cells; D006801:Humans; D051379:Mice; D008875:Middle Aged; D009368:Neoplasm Transplantation; D009369:Neoplasms / Q000097:blood*; D044967:Serum / Q000737:chemistry*
chemical_list: D019313:BRCA1 Protein; C492913:BRCA1 protein, human; D017077:Culture Media, Conditioned
keywords: BRCA1; Exosomes; Fibroblasts; Genometastasis; Metastasis; Transformation; Tumor suppressor genes