Heregulin-dependent autocrine loop regulates growth of K-ras but not erbB-2 transformed rat thyroid epithelial cells.
The EGF-like family of proteins, such as epidermal growth factor (EGF), transforming growth factor alpha (TGFalpha), amphiregulin (AR), betacellulin (BTC), cripto-1 (CR-1), and heregulin (HRG), plays an important role in the pathogenesis of several human carcinomas as autocrine growth factors. Differentiation and proliferation of rat thyroid cells in culture (FRTL-5 cells) are regulated by thyrotropin (TSH); withdrawal of TSH from culture medium produces growth arrest, whereas its addition to quiescent cells stimulates cell entry into S phase. Instead, transformed thyroid cell lines as FRTL-5H2 cell line, overexpressing erbB-2, Kimol cells, transformed by the wild-type K-ras and A6 clone, transformed by a temperature sensitive K-ras mutant, can grow without addition of TSH to the culture medium. In order to identify whether EGF-like growth factors and corresponding receptors (erbB-2, erbB-3, and erbB-4) could be involved in the autonomous growth of these transformed rat thyroid epithelial cells, Northern blot for mRNA analysis and Western blot for protein expression were performed. In contrast to normal control FRTL-5 cells, both K-ras and erbB-2-transformed cells expressed elevated levels of erbB-2 receptor. Moreover, both K-ras transformed cells, Kimol and A6 cells, but no FRTL-5H2 cells, were found able to express also high levels of erbB-4 receptor and HRG/NDF ligand. Treatment of K-ras transformed thyroid cells with neutralizing antibody against HRG/NDF reduced by 50% cell proliferation. These data indicate that unlike the erbB-2 overexpressing FRTL-5 cells, in K-ras rat thyroid epithelial cells, the growth factor heregulin signals through the heterodimer erbB-2/erbB-4 receptors in an autocrine fashion.
Mincione
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Dipartimento di Oncologia e Neuroscienze, Cattedra di Patologia Generale, Facoltà di Medicina e Chirurgia, Università G. D'Annunzio, Chieti, Italy.
Piccirelli
A
A
Lazzereschi
D
D
Salomon
D S
DS
Colletta
G
G
D066258:Amphiregulin; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D000970:Antineoplastic Agents / Q000378:metabolism; D019898:Autocrine Communication / Q000502:physiology*; D066259:Betacellulin; D001667:Binding, Competitive / Q000276:immunology; D001943:Breast Neoplasms; D002352:Carrier Proteins / Q000235:genetics* / Q000276:immunology; D002461:Cell Line, Transformed / Q000737:chemistry / Q000502:physiology; D003110:Colonic Neoplasms; D066255:EGF Family of Proteins; D004815:Epidermal Growth Factor; D004847:Epithelial Cells / Q000737:chemistry / Q000502:physiology; D066246:ErbB Receptors / Q000235:genetics; D058851:GPI-Linked Proteins; D015870:Gene Expression / Q000502:physiology; D006023:Glycoproteins / Q000235:genetics* / Q000276:immunology; D006133:Growth Substances / Q000235:genetics; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins / Q000235:genetics; D020890:Neuregulin-1; D009500:Neutralization Tests; D011518:Proto-Oncogene Proteins / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000235:genetics*; D020893:Receptor, ErbB-3; D066247:Receptor, ErbB-4; D013961:Thyroid Gland / Q000166:cytology*; D014407:Tumor Cells, Cultured; D018631:ras Proteins / Q000235:genetics*
D066258:Amphiregulin; D000906:Antibodies; D000970:Antineoplastic Agents; D066259:Betacellulin; D002352:Carrier Proteins; D066255:EGF Family of Proteins; D004815:Epidermal Growth Factor; D066246:ErbB Receptors; D058851:GPI-Linked Proteins; D006023:Glycoproteins; D006133:Growth Substances; D036341:Intercellular Signaling Peptides and Proteins; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D020890:Neuregulin-1; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D018719:Erb-b2 Receptor Tyrosine Kinases; D020893:Receptor, ErbB-3; D066247:Receptor, ErbB-4; D018631:ras Proteins; C587848:AREG protein, human; C587850:Areg protein, rat; C587851:BTC protein, human; C587853:Btc protein, rat; C070636:TDGF1 protein, human; C087230:heregulin beta1; C587689:ERBB4 protein, human; C587691:Erbb4 protein, rat