The tumor-associated antigen 90K/Mac-2-binding protein secreted by human colon carcinoma cells enhances extracellular levels of promatrilysin and is a novel substrate of matrix metalloproteinases-2, -7 (matrilysin) and -9: Implications of proteolytic cleavage.
BACKGROUND
The tumor-associated antigen 90K (TAA90K)/Mac-2-binding protein is expressed at elevated level in cancerous tissues and associated with poor prognosis. Since TAA90K has been implicated in the restructuring of the extracellular matrix, we examined the functional relationship between colon cancer cell-derived TAA90K and the matrix metalloproteinase (MMP) promatrilysin (proMMP-7), and also tested whether TAA90K is a novel substrate for MMPs-2, -7 and -9.


METHODS
The effect of TAA90K on proMMP-7 levels in HT-29 conditioned media was quantified by enzyme-linked immunosorbent assays. Binding of TAA90K to MMPs, extracellular matrix proteins and galectin-3 was measured by solid-phase binding assays. Proteolytic cleavage of TAA90K by MMPs was documented by SDS-PAGE and protein sequencing analysis.


RESULTS
TAA90K enhanced extracellular levels of proMMP-7 in HT-29 cells. In addition, TAA90K was cleaved by MMPs-2, -7 and -9. MMP-7-mediated cleavage of TAA90K did not affect its binding to MMP-7, laminin-1, collagen IV and galectin-3 but reduced its interaction with fibronectin and laminin-10, and lowered the levels of proMMP-7 in the HT-29 medium.


CONCLUSIONS
TAA90K is a novel substrate for MMPs-2, -7 and -9 and modulates proMMP-7 levels in colon cancer cells.


CONCLUSIONS
Proteolytic cleavage of TAA90K may have functional implications in colon cancer.
Ulmer
Tricia A
TA
Department of Biochemistry, University of Saskatchewan, 107 Wiggins Road, Room A3, Saskatoon, Saskatchewan, Canada S7N 5E5.
Keeler
Vicki
V
André
Sabine
S
Gabius
Hans-Joachim
HJ
Loh
Lambert
L
Laferté
Suzanne
S
D000951:Antigens, Neoplasm / Q000302:isolation & purification / Q000378:metabolism*; D014408:Biomarkers, Tumor; D045744:Cell Line, Tumor; D003110:Colonic Neoplasms / Q000378:metabolism* / Q000473:pathology; D004792:Enzyme Precursors / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D020778:Matrix Metalloproteinase 2 / Q000378:metabolism*; D020783:Matrix Metalloproteinase 7 / Q000378:metabolism*; D020780:Matrix Metalloproteinase 9 / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000302:isolation & purification / Q000378:metabolism*; D008666:Metalloendopeptidases / Q000378:metabolism*; D010446:Peptide Fragments / Q000302:isolation & purification / Q000378:metabolism; D011379:Prognosis; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism; D013379:Substrate Specificity; D014616:Vaccinia virus / Q000235:genetics
D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D004792:Enzyme Precursors; D008562:Membrane Glycoproteins; D010446:Peptide Fragments; D011994:Recombinant Proteins; C114782:TAA90K protein, human; D008666:Metalloendopeptidases; C099583:promatrilysin; D020783:Matrix Metalloproteinase 7; D020778:Matrix Metalloproteinase 2; D020780:Matrix Metalloproteinase 9