title: Therapeutic ultrasound stimulates MC3T3-E1 cell proliferation through the activation of NF-κB1, p38α, and mTOR.
abstract: OBJECTIVE
  As the population ages, osteometabolic diseases and osteoporotic fractures emerge, resulting in substantial healthcare resource utilization and impaired quality of life. Many types of mechanical stimulation have the potential of being recognized by bone cells after a mechanical sign is transformed into a biological one (a process called mechanotransduction). The therapeutic ultrasound (TU) is one of several resources capable of promoting bone cell mechanical stimulation. Therefore, the main purpose of present study was to evaluate the effect of TU on the proliferation of pre-osteoblasts using in vitro bioassays.
  
  
  METHODS
  We used MC3T3-E1 pre-osteoblast lineage cells kept in Alpha medium. Cells were treated using pulsed mode therapeutic ultrasound, with frequency of 1 MHz, intensity of 0.2 W/cm(2) (SATA), duty cycle of 20%, for 30 minutes. Nifedipine and rapamycin were used to further investigate the role of L-type Ca(2+) channels and mTOR pathway. Intracellular calcium, TGF-β1, magnesium, and the mRNA levels of osteopontin, osteonectin, NF-κB1, p38α were evaluated.
  
  
  RESULTS
  The results show that TU stimulates the growth of MC3T3-E1 cells and decreases the supernatant calcium and magnesium content. Also, it increases intracellular calcium, activates NF-κB1 and mTOR complex via p38α. Moreover, TU promoted a decrease in the TGF-β1 synthesis, which is a cell growth inhibitor.
  
  
  CONCLUSIONS
  Therapeutic ultrasound, with frequency of 1 MHz, intensity of 0.2 W/cm(2) (SATA) and pulsed mode, for 30 minutes, was able to increase the proliferation of preosteoblast-like bone cells. This effect was mediated by a calcium influx, with a consequent activation of the mTOR pathway, through increased NF-κB1 and p38α.
authors.affiliation: Univates, Lajeado, Rio Grande do Sul, Brazil.|Laboratório de Pesquisa em Biofísica Celular e Inflamação, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: João A F
authors.initials: JA
authors.lastname: Tassinary
authors.affiliation: Laboratório de Pesquisa em Biofísica Celular e Inflamação, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Adroaldo
authors.initials: A
authors.lastname: Lunardelli
authors.affiliation: Laboratório de Pesquisa em Biofísica Celular e Inflamação, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Bruno S
authors.initials: BS
authors.lastname: Basso
authors.affiliation: Univates, Lajeado, Rio Grande do Sul, Brazil.
authors.forename: Simone
authors.initials: S
authors.lastname: Stülp
authors.affiliation: Univates, Lajeado, Rio Grande do Sul, Brazil.
authors.forename: Adriane
authors.initials: A
authors.lastname: Pozzobon
authors.affiliation: Laboratório de Pesquisa em Biofísica Celular e Inflamação, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Leonardo
authors.initials: L
authors.lastname: Pedrazza
authors.affiliation: Universitat de Barcelona, Barcelona, Spain.
authors.forename: Ramon
authors.initials: R
authors.lastname: Bartrons
authors.affiliation: Universitat de Barcelona, Barcelona, Spain.
authors.forename: Francesc
authors.initials: F
authors.lastname: Ventura
authors.affiliation: Universitat de Barcelona, Barcelona, Spain.
authors.forename: Jose L
authors.initials: JL
authors.lastname: Rosa
authors.affiliation: Laboratório de Pesquisa em Biofísica Celular e Inflamação, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Denizar A S
authors.initials: DA
authors.lastname: Melo
authors.affiliation: Laboratório de Pesquisa em Biofísica Celular e Inflamação, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Fernanda B
authors.initials: FB
authors.lastname: Nunes
authors.affiliation: Laboratório de Pesquisa em Biofísica Celular e Inflamação, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Márcio V F
authors.initials: MV
authors.lastname: Donadio
authors.affiliation: Laboratório de Pesquisa em Biofísica Celular e Inflamação, Pontifícia Universidade Católica do Rio Grande do Sul (PUCRS), Porto Alegre, Rio Grande do Sul, Brazil.
authors.forename: Jarbas R
authors.initials: JR
authors.lastname: Oliveira
mesh_terms: D016475:3T3 Cells; D000818:Animals; D018929:Cell Culture Techniques; D002454:Cell Differentiation; D049109:Cell Proliferation / Q000528:radiation effects*; D051379:Mice; D048308:Mitogen-Activated Protein Kinase 14 / Q000502:physiology*; D016328:NF-kappa B / Q000502:physiology*; D010006:Osteoblasts / Q000378:metabolism / Q000473:pathology / Q000528:radiation effects*; D058570:TOR Serine-Threonine Kinases / Q000502:physiology*; D014464:Ultrasonic Therapy
chemical_list: D016328:NF-kappa B; D058570:TOR Serine-Threonine Kinases; D048308:Mitogen-Activated Protein Kinase 14
keywords: calcium; mechanotransduction; osteoblast; osteometabolic diseases