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C H Blood

Publications and source records attributed to C H Blood.

5 recordsLinked to original sources
PubMed1993

Laminin regulates a tumor cell chemotaxis receptor through the laminin-binding integrin subunit alpha 6.

Chemotaxis of the M27 variant of Lewis lung carcinoma to VGVAPG, an elastin-derived chemoattractant, is restricted by the basement membrane glycoprotein laminin. Laminin does not inhibit random migration of M27 tumor cells, nor does it inhibit M27 cell chemotaxis to a second chemotactic peptide, fMLF. The laminin sensitivity of VGVAPG chemotaxis appears to be independent of adhesion to laminin, and it is not due to competitive inhibition of VGVAPG receptor binding. Preincubation of M27 cells with laminin reduces the affinity of VGVAPG-specific binding without altering the number of available VGVAPG receptors. Reduced VGVAPG receptor affinity was previously observed: (a) a nonresponsive Lewis lung carcinoma variant, H59, expresses low-affinity VGVAPG binding and (b) maintenance of high-affinity VGVAPG receptors on M27 tumor cells is correlated with elevated protein kinase C activity in the particulate cell fraction (C. H. Blood and B. R. Zetter, J. Biol. Chem., 264: 10614-10620, 1989). The negative regulation of VGVAPG chemotaxis by laminin is consistent with these observations: laminin coordinately inhibits VGVAPG chemotaxis, reduces VGVAPG receptor affinity, and decreases protein kinase C activity in the particulate fraction of M27 cells. These parameters are not affected by a second glycoprotein, fibronectin. Anti-alpha 6 antibodies neutralize the laminin inhibition of both VGVAPG chemotaxis and protein kinase C activity. The results demonstrate that laminin can modulate cell behavior by regulating cell surface receptors for biologically active ligands.

Animals↗
PubMed1989

Membrane-bound protein kinase C modulates receptor affinity and chemotactic responsiveness of Lewis lung carcinoma sublines to an elastin-derived peptide.

The M27 and H59 variants of Lewis lung carcinoma differ in their responsiveness to the chemotactic elastin peptide Val-Gly-Val-Ala-Pro-Gly (VGVAPG). M27 cells, selected for metastasis to lung, are highly responsive to a positive gradient of VGVAPG. H59 cells, selected for metastasis to liver, do not migrate in response to VGVAPG. Although both cell types bind radiolabeled VGVAPG, Scatchard analysis of 125I-Tyr-VGVAPG binding reveals that M27 cells bind the chemoattractant with a Kd of 2.7 nM, whereas nonresponsive H59 cells bind the peptide with a Kd of 67 nM. These findings indicate that the failure of H59 cells to migrate in response to VGVAPG may be due to the reduced affinity of their VGVAPG receptors. Both receptor affinity and chemotactic responsiveness to VGVAPG can be modulated in each of these two tumor cell lines by the levels of active membrane-associated protein kinase C. Treatment of nonresponsive H59 cells with 12-O-tetradecanoylphorbol 13-acetate increases the level of membrane-bound protein kinase C activity with a concomitant increase in VGVAPG binding affinity and induction of chemotactic responsiveness to VGVAPG. Treatment of M27 cells with the protein kinase C inhibitor, staurosporine, reduces VGVAPG binding affinity and abrogates the chemotactic response. We conclude that chemotactic responsiveness of M27 and H59 tumor cells is dependent upon high VGVAPG receptor affinity, which is strongly correlated to high levels of membrane-bound protein kinase C activity.

Alkaloids↗
PubMed1989

Tumor cell interactions with elastin: implications for pulmonary metastasis.

Elastin surrounds microvessels in the pulmonary circulation and may pose a barrier to the extravasation of metastatic tumor cells. We find that lung-colonizing murine melanoma cells produce an enzymatic activity that degrades elastin. In addition, the elastin fragments liberated by enzymatic digestion of insoluble elastin stimulate tumor cell chemotaxis. Chemotactic activity is associated with other forms of soluble elastin, including alpha-elastin and tropoelastin. Val-Gly-Val-Ala-Pro-Gly, a synthetic peptide that is a repeat sequence in the elastin molecule, also displayed tumor cell chemotactic activity. The ability to degrade elastin and to migrate in response to soluble elastin peptides is not a property of all tumor cells, but it is most commonly found associated with metastatic tumor cells that colonize pulmonary tissue. We postulate that the ability to migrate in response to elastin fragments may facilitate tumor cell invasion of elastin-rich pulmonary tissue.

Animals↗
PubMed1988

Identification of a tumor cell receptor for VGVAPG, an elastin-derived chemotactic peptide.

Extracellular matrix proteins and their proteolytic products have been shown to modulate cell motility. We have found that certain tumor cells display a chemotactic response to degradation products of the matrix protein elastin, and to an elastin-derived peptide, VGVAPG. The hexapeptide VGVAPG is a particularly potent chemotaxin for lung-colonizing Lewis lung carcinoma cells (line M27), with 5 nM VGVAPG eliciting maximal chemotactic response when assayed in 48-microwell chemotaxis chambers. Binding of the elastin-derived peptide to M27 cells was studied using a tyrosinated analog (Y-VGVAPG) to allow iodination. Scatchard analysis of [125I]Y-VGVAPG binding to viable M27 tumor cells at both 37 and 4 degrees C indicates the presence of a single class of high affinity binding sites. The dissociation constant obtained from these studies (2.7 X 10(-9) M) is equivalent to the concentration of VGVAPG required for chemotactic activity. The receptor molecule was identified as an Mr 59,000 species by covalent cross-linking of the radiolabeled ligand to the M27 tumor cell surface and subsequent analysis of the cross-linked material by electrophoresis and size-exclusion high performance liquid chromatography. These results suggest that M27 tumor cell chemotaxis to VGVAPG is initiated by high affinity binding of the peptide to a distinct cell surface receptor.

Animals↗