| Autor: |
Murthy U; Department of Cell Biology, Smith Kline and French Laboratories, King of Prussia, PA 19406-2799., Anzano MA, Greig RG |
| Jazyk: |
angličtina |
| Zdroj: |
International journal of cancer [Int J Cancer] 1989 Jul 15; Vol. 44 (1), pp. 110-5. |
| DOI: |
10.1002/ijc.2910440120 |
| Abstrakt: |
Previous studies have established that colon carcinoma cells secrete several polypeptide growth factors, including TGF-alpha/EGF and TGF-beta, suggesting that these and related molecules function in an autocrine/paracrine fashion to modulate tumor-cell growth. To investigate this possibility, we have studied the expression of transforming growth factor receptors in a panel of human colon carcinoma cell lines and in several untransformed epithelial cell populations. The results have revealed that neoplastic colon cells express receptors for both TGF-alpha/EGF and TGF-beta. Immunoprecipitation identified the TGF-alpha/EGF receptor as a structurally intact 170-kDa protein. No evidence for over-expression was found. TGF-alpha (and EGF) enhanced receptor autophosphorylation, indicating that these receptors were biochemically functional. TGF-beta blocked DNA synthesis in non-neoplastic epithelial cells but not in tumorigenic colon populations. There was no correlation with TGF-beta receptor number or dissociation constant. However, chemical cross-linking studies revealed a TGF-beta receptor subtype of 75 kDa in 3 of the 4 colon carcinoma cells which was undetectable in normal IEC epithelial cultures, suggesting a possible association between 75-kDa receptor expression and refractoriness to growth inhibition of TGF-beta. Together, these data support the concept that locally-produced growth regulators can function in an autocrine or paracrine manner to influence the proliferation of colon carcinoma cells. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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