TY - JOUR
T1 - Human mammary cancer progression model recapitulates methylation events associated with breast premalignancy
AU - Dumont, Nancy
AU - Crawford, Yongping G.
AU - Sigaroudinia, Mahvash
AU - Nagrani, Shefali S.
AU - Wilson, Matthew B.
AU - Buehring, Gertrude C.
AU - Turashvili, Gulisa
AU - Aparicio, Samuel
AU - Gauthier, Mona L.
AU - Fordyce, Colleen A.
AU - McDermott, Kimberly M.
AU - Tlsty, Thea D.
N1 - Funding Information:
We would like to thank Krystyna Kozakiewicz for performing the chromosomal analysis, Chira Chen-Tanyolac for assistance with tumor DNA isolation, Dr. Sanjiv Sam Gambhir (Stanford University, Palo Alto, CA) for providing us with the GFP-luciferase lentiviral construct, and Dr. Philippe Gascard for critical discussions, review of the manuscript, and assistance with MSP primer mapping. This research was supported by the Susan G. Komen Foundation, postdoctoral award PDF124906 (ND), the NCI Institutional Training Grant T32 CA009043 (MBW), the Department of Defense Breast Cancer Research Program Concept Award BC023982 and 14OB-0165 (TDT), the NIH/NCI CA097214 and CA122024 grants (TDT).
PY - 2009/12/8
Y1 - 2009/12/8
N2 - Introduction: We have previously identified a rare subpopulation of variant human mammary epithelial cells (vHMEC) with repressed p16INK4A that exist in disease-free women yet display premalignant properties, suggesting that they have engaged the process of malignant transformation. In order to gain insight into the molecular alterations required for vHMEC to progress to malignancy, and to characterize the epigenetic events associated with early progression, we examined the effect of oncogenic stress on the behavior of these cells.Methods: HMEC that express p16INK4A and vHMEC that do not, were transduced with constitutively active Ha-rasV12 and subsequently exposed to serum to determine whether signals from the cellular microenvironment could cooperate with ras to promote the malignant transformation of vHMEC. Epigenetic alterations were assessed using methylation-specific polymerase chain reaction (PCR).Results: vHMEC expressing Ha-rasV12 (vHMEC-ras) bypassed the classic proliferative arrest that has been previously documented in normal fibroblasts following oncogenic stress, and that we also observe here in normal HMEC. Moreover, vHMEC-ras cells exhibited many additional alterations that are observed during progression to malignancy such as the generation of chromosomal abnormalities, upregulation of telomerase activity, immortalization following exposure to serum, and anchorage-independent growth, but they did not form tumors following orthotopic injection in vivo. Associated with their early progression to malignancy was an increase in the number of genes methylated, two of which (RASSF1A and SFRP1) were also methylated in other immortalized mammary cell lines as well as in breast cancer cells and tissues.Conclusions: We have characterized a mammary progression model that recapitulates molecular and methylation alterations observed in many breast cancers. Our data suggest that concomitant methylation of RASSF1A and SFRP1 marks an early event in mammary transformation and may thus have prognostic potential.
AB - Introduction: We have previously identified a rare subpopulation of variant human mammary epithelial cells (vHMEC) with repressed p16INK4A that exist in disease-free women yet display premalignant properties, suggesting that they have engaged the process of malignant transformation. In order to gain insight into the molecular alterations required for vHMEC to progress to malignancy, and to characterize the epigenetic events associated with early progression, we examined the effect of oncogenic stress on the behavior of these cells.Methods: HMEC that express p16INK4A and vHMEC that do not, were transduced with constitutively active Ha-rasV12 and subsequently exposed to serum to determine whether signals from the cellular microenvironment could cooperate with ras to promote the malignant transformation of vHMEC. Epigenetic alterations were assessed using methylation-specific polymerase chain reaction (PCR).Results: vHMEC expressing Ha-rasV12 (vHMEC-ras) bypassed the classic proliferative arrest that has been previously documented in normal fibroblasts following oncogenic stress, and that we also observe here in normal HMEC. Moreover, vHMEC-ras cells exhibited many additional alterations that are observed during progression to malignancy such as the generation of chromosomal abnormalities, upregulation of telomerase activity, immortalization following exposure to serum, and anchorage-independent growth, but they did not form tumors following orthotopic injection in vivo. Associated with their early progression to malignancy was an increase in the number of genes methylated, two of which (RASSF1A and SFRP1) were also methylated in other immortalized mammary cell lines as well as in breast cancer cells and tissues.Conclusions: We have characterized a mammary progression model that recapitulates molecular and methylation alterations observed in many breast cancers. Our data suggest that concomitant methylation of RASSF1A and SFRP1 marks an early event in mammary transformation and may thus have prognostic potential.
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U2 - 10.1186/bcr2457
DO - 10.1186/bcr2457
M3 - Article
C2 - 19995452
AN - SCOPUS:77954609358
SN - 1465-5411
VL - 11
JO - Breast Cancer Research
JF - Breast Cancer Research
IS - 6
M1 - R87
ER -