Cancer metastasis suppressor KAI1/CD82 belongs to the tetraspanin superfamily and inversely correlates with the metastatic potential of a variety of cancers. The mechanism of KAI1/CD82-mediated metastasis suppression remains unclear. In this study, we found a M(r) 68,00 cell-surface protein physically associated with KAI1/CD82 and named it KASP: a KAI1/CD82-associated surface protein. Distincti...

To determine how tetraspanin KAI1/CD82, a tumor metastasis suppressor, inhibits cell migration, we assessed which cellular events critical for motility are altered by KAI1/CD82 and how KAI1/CD82 regulates these events. We found that KAI1/CD82-expressing cells typically exhibited elongated cellular tails and diminished lamellipodia. Live imaging demonstrated that the polarized protrusion and ret...

The KAI1 gene was identified as a metastasis suppressor gene for human prostate cancer. Recently, we showed that KAI1 mRNA levels were higher in an immortal, normal-like breast epithelial cell line and nonmetastatic breast cancer cell lines but lower substantially in highly metastatic breast cancer cell lines. In this study, we examined KAI1 protein expression in breast cancer cell lines by Wes...

The KAI1 gene, located on human chromosome 11p11.2, suppresses tumor metastasis when expressed in certain cancer cells. To evaluate whether dysregulation of KAI1 occurs during the progression of human prostatic cancer, protein expression, mutation, and allelic loss of KAI1 were analyzed using a tissue bank of 98 primary cancers and 32 metastases. By immunohistochemical staining, high levels of ...

Inactivation of tumor/metastasis suppressor genes via epigenetic silencing is a frequent event in human cancers. KAI1/CD82 is a metastasis suppressor gene whose normal protecting activity is deficient in twelve different solid malignancies. Here we have identified and characterized a primarily nuclear non-polyadenylated, antisense (as)-lncRNA, initiating upstream of the KAI1 human metastasis su...

KAI1 is a metastasis suppressor gene for human prostate cancer and is also involved in the progression of a variety of other human cancers. Previously, we have demonstrated that KAI1 expression was down-regulated in metastatic breast cancer cell lines as well as in highly aggressive breast cancer specimens. To determine whether KAI1 expression is responsible for the metastasis suppression in br...

The tetraspanin and tumor suppressor KAI1 is downregulated or lost in many cancers which correlates with poor prognosis. KAI1 acts via physical/functional crosstalk with other membrane receptors. Also, a splice variant of KAI1 (KAI1-SP) has been identified indicative of poor prognosis. We here characterized differential effects of the two KAI1 variants on tumor biological events involving integ...

Levels of the KAI1 metastasis suppressor are reduced in advanced stages of many human cancers, leading to the loss of KAI1 function. A recent study has suggested that the loss of KAI1 function may also occur via alternative splicing of KAI1 mRNA which deletes an exon encoding a critical 28 amino acids from the protein. Using PCR, 20 bladder tumours at differing stage and grade, a non-tumourigen...

The cancer metastasis suppressor protein KAI1/CD82 is a member of the tetraspanin superfamily. Recent studies have demonstrated that tetraspanins are palmitoylated and that palmitoylation contributes to the organization of tetraspanin webs or tetraspanin-enriched microdomains. However, the effect of palmitoylation on tetraspanin-mediated cellular functions remains obscure. In this study, we fou...

The transmembrane 4 superfamily member KAI1 (CD82) has been shown to inhibit pulmonary metastases in experimental metastasis models of prostate cancer and melanoma. KAI1 expression is decreased in the progression of common solid epithelial tumors of adulthood, including lung, prostate, breast, esophageal, gastric, pancreatic, and bladder cancers. The purpose of our study was to investigate KAI1...