Role of p21 and cyclin E in normal and secalonic acid D-inhibited proliferation of human embryonic palatal mesenchymal cells.
Secalonic acid D (SAD), a cleft palate-inducing teratogen, has been shown to inhibit proliferation/cell cycle progression in association with alteration in the levels of cell cycle regulators, p21 and cyclin E. These studies were conducted to test the hypotheses that p21 and cyclin E play an important functional role in normal human embryonic palatal mesenchymal (HEPM) cell cycle and that their up- and down-regulation, respectively, by SAD is functionally significant to its cell cycle block. Using small interfering RNA (siRNA) to silence p21 gene and transient transfection to overexpress cyclin E in control & SAD-treated HEPM cells, cell proliferation was assessed using a combination of cell numbers, thymidine uptake, CDK2 activity and Ki-67 expression. The results showed that silencing of p21 gene, although increased cell proliferation/numbers and CDK2 activity in normal HEPM cells, failed to counteract SAD-induced anti-proliferative effect despite inducing partial recovery of CDK2 activity. Similar effects were apparent with cyclin E overexpression. It is concluded that p21 and cyclin E are important for normal HEPM cell proliferation. However, SAD-induced deregulation of either protein, singly, may not be sufficient to induce anti-proliferative effect. Involvement of other cell cycle proteins such as cyclin D1 or of multiple proteins in SAD-induced cell cycle block needs to be examined.
Department of Safety Assessment, Merck & Co, West Point, PA, USA.
Vamsidhara C
VC
Dhulipala
Kamala K
KK
Maddali
Bimal K
BK
Ray
Wade V
WV
Welshons
Chada S
CS
Reddy
D018929:Cell Culture Techniques; D002453:Cell Cycle / Q000187:drug effects; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects*; D019927:Cyclin E / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D050759:Cyclin-Dependent Kinase Inhibitor p21 / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020868:Gene Silencing; D006801:Humans; D015151:Immunoblotting; D008648:Mesoderm / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010159:Palate / Q000166:cytology / Q000187:drug effects* / Q000196:embryology / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D044004:Xanthones / Q000494:pharmacology*
C493956:CDKN1A protein, human; D019927:Cyclin E; D050759:Cyclin-Dependent Kinase Inhibitor p21; D034741:RNA, Small Interfering; D044004:Xanthones; C009218:secalonic acid