More than 95% of cancer patients succumb to the disease due to metastases which is the hallmark of malignant cancer. Despite significant improvements in recent surgical techniques and chemotherapies, none of the current medical technologies "cure" the metastatic disease, and the patients who have acquired metastatic cancer inevitably die. Therefore, there is an urgent need for developing a novel target-specific therapy to metastatic tumor cells, which requires more comprehensive understanding of the molecular mechanism of metastases. The KAI1 gene (also called CD82), is a tumor metastases suppressor whose expression is significantly down-regulated in various types of cancers, and over-expression of this gene is capable of blocking metastases without affecting the primary tumor growth in vivo. However, the exact molecular mechanism of the metastases suppression has not been well understood. We have recently found that (i) KAI1 on tumor cells interacts with DARC on endothelial cell, (ii) the interaction of KAI1-DARC up-regulated p21 and down-regulated TBX2, (iii) this modulation of TBX2-p21 signal lead to senescence of tumor cell, and (iv) metastases suppressor activity of KAI1 is significantly compromised in DARC knockout mouse. These results highlight a previously unappreciated function of the DARC gene and identified the KAI-DARC signal as a novel candidate for potential therapeutic intervention for metastatic cancer. Based on our preliminary data we hypothesize that KAI1 forms a "multi-protein complex" with integrins, tetraspanins and PKC and that when the cancer cell intravasates, KAI1 binds to DARC on an endothelial cell followed by activation/inactivation of PKC, which results in up-regulation of p21 and induction of senescence of the cancer cell. To test this hypothesis, we will (i) examine the role of each factor of the multi-protein complex including integrins, kitenin, EGFR, c-Met, CD63, CD9 and PKC in the metastasis suppressor function of KAI1, (ii) examine the signal pathway of senescence induced by KAI1-DARC interaction and (iii) examine therapeutic potential of targeting KAI1-DARC signal by testing anti-KAI1 antibody and also by identifying small chemicals. Our long-term goal is to elucidate the functional role of KAI1 in tumor metastases suppression and to develop a novel therapeutic method which mimics the function of the KAI1 gene. We believe that the results of the proposed experiments should provide fundamental information to accomplish our ultimate goal, the control of tumor metastasis in cancer patients.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
7R01CA129000-07
Application #
8569176
Study Section
Tumor Progression and Metastasis Study Section (TPM)
Program Officer
Woodhouse, Elizabeth
Project Start
2007-09-01
Project End
2014-07-31
Budget Start
2012-12-01
Budget End
2014-07-31
Support Year
7
Fiscal Year
2012
Total Cost
$199,395
Indirect Cost
$61,405
Name
University of Mississippi Medical Center
Department
None
Type
Schools of Medicine
DUNS #
928824473
City
Jackson
State
MS
Country
United States
Zip Code
39216
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Okuda, Hiroshi; Xing, Fei; Pandey, Puspa R et al. (2013) miR-7 suppresses brain metastasis of breast cancer stem-like cells by modulating KLF4. Cancer Res 73:1434-44
Okuda, Hiroshi; Kobayashi, Aya; Xia, Bo et al. (2012) Hyaluronan synthase HAS2 promotes tumor progression in bone by stimulating the interaction of breast cancer stem-like cells with macrophages and stromal cells. Cancer Res 72:537-47
Pandey, Puspa R; Liu, Wen; Xing, Fei et al. (2012) Anti-cancer drugs targeting fatty acid synthase (FAS). Recent Pat Anticancer Drug Discov 7:185-97
Liu, Wen; Xing, Fei; Iiizumi-Gairani, Megumi et al. (2012) N-myc downstream regulated gene 1 modulates Wnt-β-catenin signalling and pleiotropically suppresses metastasis. EMBO Mol Med 4:93-108

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