title: Mesenchymal stromal cells having inactivated RB1 survive following low irradiation and accumulate damaged DNA: Hints for side effects following radiotherapy.
abstract: Following radiotherapy, bone sarcomas account for a significant percentage of recurring tumors. This risk is further increased in patients with hereditary retinoblastoma that undergo radiotherapy. We analyzed the effect of low and medium dose radiation on mesenchymal stromal cells (MSCs) with inactivated RB1 gene to gain insights on the molecular mechanisms that can induce second malignant neoplasm in cancer survivors. MSC cultures contain subpopulations of mesenchymal stem cells and committed progenitors that can differentiate into mesodermal derivatives: adipocytes, chondrocytes, and osteocytes. These stem cells and committed osteoblast precursors are the cell of origin in osteosarcoma, and RB1 gene mutations have a strong role in its pathogenesis. Following 40 and 2000 mGy X-ray exposure, MSCs with inactivated RB1 do not proliferate and accumulate high levels of unrepaired DNA as detected by persistence of gamma-H2AX foci. In samples with inactivated RB1 the radiation treatment did not increase apoptosis, necrosis or senescence versus untreated cells. Following radiation, CFU analysis showed a discrete number of cells with clonogenic capacity in cultures with silenced RB1. We extended our analysis to the other members of retinoblastoma gene family: RB2/P130 and P107. Also in the MSCs with silenced RB2/P130 and P107 we detected the presence of cells with unrepaired DNA following X-ray irradiation. Cells with unrepaired DNA may represent a reservoir of cells that may undergo neoplastic transformation. Our study suggests that, following radiotherapy, cancer patients with mutations of retinoblastoma genes may be under strict controls to evaluate onset of secondary neoplasms following radiotherapy.
authors.affiliation: a Department of Experimental Medicine , Biotechnology and Molecular Biology Section, Second University of Naples , Naples , Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Alessio
authors.affiliation: a Department of Experimental Medicine , Biotechnology and Molecular Biology Section, Second University of Naples , Naples , Italy.
authors.forename: Stefania
authors.initials: S
authors.lastname: Capasso
authors.affiliation: a Department of Experimental Medicine , Biotechnology and Molecular Biology Section, Second University of Naples , Naples , Italy.
authors.forename: Giovanni
authors.initials: G
authors.lastname: Di Bernardo
authors.affiliation: b Department "F. Magrassi - A. Lanzara" Second University of Naples , Naples , Italy.
authors.forename: Salvatore
authors.initials: S
authors.lastname: Cappabianca
authors.affiliation: c Dipartimento della Donna , del Bambino e di Chirurgia Generale e Specialistica, Second University of Naples , Naples , Italy.
authors.forename: Fiorina
authors.initials: F
authors.lastname: Casale
authors.affiliation: d Institute of Bioscience and Bioresources, CNR , Naples , Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Calarco
authors.affiliation: a Department of Experimental Medicine , Biotechnology and Molecular Biology Section, Second University of Naples , Naples , Italy.
authors.forename: Marilena
authors.initials: M
authors.lastname: Cipollaro
authors.affiliation: b Department "F. Magrassi - A. Lanzara" Second University of Naples , Naples , Italy.
authors.forename: Gianfranco
authors.initials: G
authors.lastname: Peluso
authors.affiliation: a Department of Experimental Medicine , Biotechnology and Molecular Biology Section, Second University of Naples , Naples , Italy.
authors.forename: Umberto
authors.initials: U
authors.lastname: Galderisi
mesh_terms: D017209:Apoptosis / Q000528:radiation effects; D002453:Cell Cycle / Q000528:radiation effects; D019070:Cell Lineage / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D002471:Cell Transformation, Neoplastic / Q000378:metabolism / Q000528:radiation effects; D016922:Cellular Senescence / Q000528:radiation effects; D003114:Colony-Forming Units Assay; D004249:DNA Damage; D004260:DNA Repair / Q000528:radiation effects; D020868:Gene Silencing; D006657:Histones / Q000378:metabolism; D006801:Humans; D059630:Mesenchymal Stem Cells / Q000166:cytology* / Q000378:metabolism / Q000528:radiation effects*; D011878:Radiotherapy / Q000009:adverse effects*; D016160:Retinoblastoma Protein / Q000378:metabolism*; D050720:Retinoblastoma-Like Protein p107 / Q000378:metabolism; D014965:X-Rays
chemical_list: C468783:H2AX protein, human; D006657:Histones; D016160:Retinoblastoma Protein; D050720:Retinoblastoma-Like Protein p107
keywords: Apoptosis; DNA damage; mesenchymal stem cells; senescence