Physical and biological characterization of a growth-inhibitory activity purified from the neuroepithelioma cell line A673.
Epithelial- and haematopoietic-cell growth-inhibitory activities have been identified in the conditioned medium of the human peripheral neuroepithelioma cell line A673. An A673-cell-derived growth-inhibitory activity was previously fractionated into two distinct components which inhibited the proliferation of human carcinoma and leukaemia cells in culture. One inhibitory activity was shown to comprise interleukin-1 alpha (IL-1 alpha). Here, we have purified to homogeneity a distinct activity which inhibited the growth of the epithelial cells in vitro. Using a combination of protein-sequence analysis and mass spectrometry, we demonstrated that biological activity can be assigned to a dimeric protein with a molecular mass of 25,576 (+/- 4) Da and an N-terminal sequence identical with that of transforming growth factor-beta 1 (TGF-beta 1). Further characterization of the growth inhibitor with TGF-beta-isoform-specific antibodies showed that > 90% of the bioactivity consists of TGF-beta 1 and not TGF-beta 2 or TGF-beta 3. Although A673 cells were growth-inhibited by exogenous TGF-beta 1, we showed that TGF-beta 1 in A673-cell-conditioned media was present in the latent, biologically inactive, form which did not act as an autocrine growth modulator of A673 cells in vitro.
Stam
K
K
Pharmaceuticals Division, Oncogene Science, Uniondale, NY 11553.
Stewart
A A
AA
Qu
G Y
GY
Iwata
K K
KK
Fenyö
D
D
Chait
B T
BT
Marshak
D R
DR
Haley
J D
JD
D000595:Amino Acid Sequence; D000906:Antibodies / Q000494:pharmacology; D000918:Antibody Specificity; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003470:Culture Media; D006133:Growth Substances / Q000737:chemistry / Q000302:isolation & purification* / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D018241:Neuroectodermal Tumors, Primitive, Peripheral / Q000737:chemistry* / Q000473:pathology*; D009500:Neutralization Tests; D017386:Sequence Homology, Amino Acid; D016212:Transforming Growth Factor beta / Q000032:analysis / Q000276:immunology; D014407:Tumor Cells, Cultured
D000906:Antibodies; D003470:Culture Media; D006133:Growth Substances; D016212:Transforming Growth Factor beta