Glycoprotein 90K, downregulated in advanced colorectal cancer tissues, interacts with CD9/CD82 and suppresses the Wnt/beta-catenin signal via ISGylation of beta-catenin.
OBJECTIVE
90K, a tumour-associated glycoprotein, interacts with galectins and has roles in host defence by augmenting the immune response, but the serum 90K level was suggested to indicate poor prognosis in several cancers. The cellular mechanisms of 90K action on colorectal cancer (CRC) cell motility and its effect on CRC progression were investigated.


METHODS
The impact of 90K was analysed by combining cell cultures, in vitro assays, and immunohistochemistry.


RESULTS
Secreted 90K suppresses CRC cell invasion, but this action of 90K is masked through binding with extracellular galectins. A novel pathway is identified comprising a secretory 90K and a CD9/CD82 tetraspanin web; in this pathway, 90K interacts with CD9/CD82, suppresses the Wnt/beta-catenin signal via a novel proteasomal-ubiquitination mechanism of beta-catenin that is dependent on ISG15 (interferon-stimulated gene-15) modification (ISGylation) but not on glycogen synthase kinase 3beta (GSK-3beta) and Siah/Adenomatous polyposis coli (APC). In a syngeneic mouse colon tumour model, tumour growth and lung metastasis were increased with 90K knockdown. In colon tissues from stage IV human CRC and invading cancer cells of corresponding metastatic liver tissues, in which beta-catenin and galectin expression was higher, immunostained 90K and CD9/CD82 were lower than in adjacent hepatic tissues or colon tissues from stage I.


CONCLUSIONS
90K itself has antitumour activity in CRC cells via suppression of Wnt signalling with a novel mechanism of ISGylation-dependent ubiquitination of beta-catenin when it interacts with CD9/CD82, but is downregulated in advanced CRC tissues. The data suggest a strategy of strengthening this novel pathway with concomitant knockdown of galectins as a potential therapeutic approach to CRC progression.
Lee
Ji Hee
JH
Department of Pharmacology, Chonnam National University Medical School, Hak-Dong 5, Dong-Ku, Kwangju, Korea.
Bae
Jeong A
JA
Lee
Jae Hyuk
JH
Seo
Young-Woo
YW
Kho
Dhong Hyo
DH
Sun
Eun Gene
EG
Lee
Song Eun
SE
Cho
Sang Hee
SH
Joo
Young Eun
YE
Ahn
Kyu Youn
KY
Chung
Ik Joo
IJ
Kim
Kyung Keun
KK
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism*; D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D002352:Carrier Proteins; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology; D017077:Culture Media, Conditioned / Q000494:pharmacology; D016207:Cytokines / Q000502:physiology; D004195:Disease Models, Animal; D015536:Down-Regulation / Q000502:physiology; D037161:Galectins / Q000378:metabolism; D006023:Glycoproteins / Q000378:metabolism* / Q000502:physiology; D006801:Humans; D051861:Kangai-1 Protein / Q000378:metabolism*; D007785:Lactose / Q000494:pharmacology; D008113:Liver Neoplasms / Q000378:metabolism / Q000556:secondary; D008175:Lung Neoplasms / Q000378:metabolism / Q000517:prevention & control / Q000556:secondary; D008562:Membrane Glycoproteins / Q000378:metabolism*; D051379:Mice; D009363:Neoplasm Proteins / Q000378:metabolism* / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology; D060245:Tetraspanin 29; D014407:Tumor Cells, Cultured; D025801:Ubiquitin / Q000378:metabolism; D014452:Ubiquitins / Q000502:physiology; D051153:Wnt Proteins / Q000378:metabolism; D051176:beta Catenin / Q000378:metabolism*; D016326:Extracellular Matrix Proteins
D015703:Antigens, CD; D000951:Antigens, Neoplasm; D014408:Biomarkers, Tumor; D002352:Carrier Proteins; D017077:Culture Media, Conditioned; D016207:Cytokines; D037161:Galectins; D006023:Glycoproteins; D051861:Kangai-1 Protein; D007785:Lactose; D008562:Membrane Glycoproteins; D009363:Neoplasm Proteins; D060245:Tetraspanin 29; D025801:Ubiquitin; D014452:Ubiquitins; D051153:Wnt Proteins; D051176:beta Catenin; C497688:CD82 protein, human; C554869:CD9 protein, human; C495270:CTNNB1 protein, human; C554870:Cd9 protein, mouse; C081856:LGALS3BP protein, human; D016326:Extracellular Matrix Proteins; C074034:ISG15 protein, human