title: Cellular alterations and modulation of protein expression in bitumen-challenged human osteoblast cells.
abstract: OBJECTIVE
  There are many arguments on the carcinogenic potential of bitumen extract. The mechanism of bitumen-induced damage is not well understood at the molecular level. Therefore, in the present study, cell-transforming and tumor-inducing potential of bitumen extract was studied using in vitro [human osteosarcoma (HOS) cells] and in vivo [nude and severe combined immunodeficiency (SCID) mice] models.
  
  
  METHODS
  Gas chromatography/mass spectrometry (GC/MS) analysis was carried out to find out the existence of carcinogenic compounds in the bitumen extract. Cell transformation test, anchorage independence assay, karyotyping assay, tumorigenicity assay, and 2-DE analysis were used to find out the effect of bitumen using the in vitro and in vivo models.
  
  
  RESULTS
  GC/MS analysis showed the existence of carcinogenic compounds in the bitumen extract. HOS cells were treated with different concentrations (25, 50, and 100 μl/ml) of bitumen extract. Compared to the parental HOS cells, bitumen transformants (HOS T1 and HOS T2) showed the characteristics of anchorage independency, chromosomal anomaly, and cellular transformation. Interestingly, bitumen transformants were not able to form tumor in nude/SCID mice. Proteomic analysis revealed the existence of 19 differentially expressed proteins involved in progression of cancer, angiogenesis, cell adhesion, etc.
  
  
  CONCLUSIONS
  Exposure of bitumen extract to HOS cells results in the cellular transformation similar to cancer cells and can modulate proteins involved in the progression of cancer. We state that the non-tumorogenic potential of bitumen transformant in nude/SCID mice can be attributed to the downregulation of galectin-1, chromodomain helicase DNA-binding protein 1-like gene, and membrane-associated guanylate kinase 2 protein.
authors.affiliation: National Environmental Engineering Research Institute, Nehru Marg, Nagpur, India.
authors.forename: Alka
authors.initials: A
authors.lastname: Dhondge
authors.forename: Subin
authors.initials: S
authors.lastname: Surendran
authors.forename: Muhil Vannan
authors.initials: MV
authors.lastname: Seralathan
authors.forename: Pravin K
authors.initials: PK
authors.lastname: Naoghare
authors.forename: Kannan
authors.initials: K
authors.lastname: Krishnamurthi
authors.forename: Sivanesan Saravana
authors.initials: SS
authors.lastname: Devi
authors.forename: Tapan
authors.initials: T
authors.lastname: Chakrabarti
mesh_terms: D000818:Animals; D002273:Carcinogens / Q000633:toxicity; D002471:Cell Transformation, Neoplastic / Q000139:chemically induced; D005260:Female; D015870:Gene Expression / Q000187:drug effects*; D015386:Hazardous Substances / Q000633:toxicity*; D006801:Humans; D006838:Hydrocarbons / Q000633:toxicity*; D051379:Mice; D008819:Mice, Nude; D010006:Osteoblasts; D020543:Proteome / Q000378:metabolism*
chemical_list: D002273:Carcinogens; D015386:Hazardous Substances; D006838:Hydrocarbons; D020543:Proteome; C006647:asphalt