GADD45-alpha expression in cirrhosis and hepatocellular carcinoma: relationship with DNA repair and proliferation.
Growth arrest and DNA damage 45-alpha (GADD45-alpha) is a nuclear protein involved in maintenance of genomic stability, DNA repair, and suppression of cell growth through interaction with nuclear elements, including cyclin-dependent kinase inhibitor 1A (CDKN1A) and PCNA. In this study, GADD45-alpha expression was assessed in 28 cases of hepatocellular carcinoma (HCC) and matched cirrhosis tissues, and correlated with the presence of DNA-bound PCNA and CDKN1A as markers of DNA repair, as well as with clinicopathologic variables including histopathologic grade, tumor size, nodularity, viral status, alpha-fetoprotein serum levels, and p53 and Ki67 immunostaining. GADD45-alpha and CDKN1A messenger RNA (mRNA) were analyzed by reverse transcriptase-polymerase chain reaction. GADD45-alpha protein expression was evaluated by Western blot (WB) and enzyme-linked immunosorbent assays (ELISAs). PCNA and CDKN1A DNA-bound fractions were determined by WB. GADD45-alpha mRNA was down-regulated in 20 of 26 HCCs with respect to matched cirrhosis, but no correlation was found with the corresponding protein levels assessed by both WB and ELISA. GADD45-alpha and CDKN1A protein levels were related to each other both in cirrhotic and in neoplastic tissues, and a concordant up- or down-regulation was observed in HCCs with respect to cirrhosis. DNA-bound PCNA and CDKN1A were present in 5 HCCs and were associated with higher GADD45-alpha protein levels assessed by ELISA. No significant association was found in HCCs between GADD45-alpha protein expression and histopathologic grading, nodule size, focality, and proliferation, whereas a positive correlation was found with alpha-fetoprotein serum levels. In conclusion, GADD45-alpha mRNA was down-regulated with respect to matched cirrhosis in most HCCs; however, no correlation was found between mRNA and protein levels. GADD45-alpha protein levels were higher in HCCs with DNA-bound CDKN1A and PCNA, suggesting a possible role in DNA repair.
Gramantieri
Laura
L
Center for Applied Biomedical Research (CRBA), Saint Orsola-Malpighi University Hospital, University of Bologna, 40138 Bologna, Italy. lauragram@hotmail.com
Chieco
Pasquale
P
Giovannini
Catia
C
Lacchini
Michela
M
Treré
Davide
D
Grazi
Gian Luca
GL
Venturi
Annamaria
A
Bolondi
Luigi
L
D000368:Aged; D015153:Blotting, Western; D006528:Carcinoma, Hepatocellular / Q000378:metabolism* / Q000473:pathology; D018797:Cell Cycle Proteins / Q000096:biosynthesis*; D049109:Cell Proliferation; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000096:biosynthesis; D004260:DNA Repair / Q000502:physiology*; D015536:Down-Regulation; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D008103:Liver Cirrhosis / Q000378:metabolism* / Q000473:pathology; D008113:Liver Neoplasms / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D009687:Nuclear Proteins / Q000096:biosynthesis*; D018809:Proliferating Cell Nuclear Antigen / Q000096:biosynthesis; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D000097642:GADD45 Proteins
D018797:Cell Cycle Proteins; D050759:Cyclin-Dependent Kinase Inhibitor p21; D009687:Nuclear Proteins; D018809:Proliferating Cell Nuclear Antigen; D012333:RNA, Messenger; C439070:GADD45A protein, human; D000097642:GADD45 Proteins