Keiichi Koizumi

Role of the CXCL12/CXCR4 axis in Peritoneal Carcinomatosis of Gastric Cancer

Peritoneal carcinomatosis is a frequent cause of death in patients with advanced gastric carcinoma. Because chemokines are now considered to play an important role in the metastasis of various malignancies, we hypothesized that they may be involved in the development of peritoneal carcinomatosis by gastric carcinoma. Human gastric carcinoma cell lines, which were all highly efficient in generating malignant ascites in nude mice upon i.p. inoculation, selectively expressed CXCR4 mRNA and protein. In particular, NUGC4 cells expressed CXCR4 mRNA at high levels and showed vigorous migratory responses to its ligand CXCL12. CXCL12 enhanced proliferation and rapid increases in phosphorylation of protein kinase B/Akt and extracellular signal-regulated kinase of NUGC4 cells. We also showed that AMD3100 (a specific CXCR4 antagonist) effectively reduced tumor growth and ascitic fluid formation in nude mice inoculated with NUGC4 cells. Additionally, we examined human clinical samples. Malignant ascitic fluids from patients with peritoneal carcinomatosis contained high concentrations of CXCL12 (4.67 ng/mL). Moreover, immunohistochemical analysis showed that 22 of 33 primary gastric tumors with peritoneal metastasis were positive for CXCR4 expression (67%), whereas only 4 of 16 with other distant metastasis were positive (25%). Notably, 22 of 26 CXCR4-expressing primary tumors developed peritoneal metastases (85%). CXCR4 positivity of primary gastric carcinomas significantly correlated with the development of peritoneal carcinomatosis (P < 0.001). Collectively, our results strongly suggest that the CXCR4/CXC12 axis plays an important role in the development of peritoneal carcinomatosis from gastric carcinoma. Thus, CXCR4 may be a potential therapeutic target for peritoneal carcinomatosis of gastric carcinoma.

Chemokine receptors in cancer metastasis and cancer cell‐derived chemokines in host immune response

The chemotactic cytokines called chemokines are a superfamily of small secreted cytokines that were initially characterized through their ability to prompt the migration of leukocytes. Attention has been focused on the chemokine receptors expressed on cancer cells because cancer cell migration and metastasis show similarities to leukocyte trafficking. CXC chemokine receptor 4 (CXCR4) was first investigated as a chemokine receptor that is associated with lung metastasis of breast cancers. Recently, CXCR4 was reported to be a key molecule in the formation of peritoneal carcinomatosis in gastric cancer. In the present review, we highlight current knowledge about the role of CXCR4 in cancer metastases. In contrast to chemokine receptors expressed on cancer cells, little is known about the roles of cancer cell‐derived chemokines. Cancer tissue consists of both cancer cells and various stromal cells, and leukocytes that infiltrate into cancer are of particular importance in cancer progression. Although colorectal cancer invasion is regulated by the chemokine CCL9‐induced infiltration of immature myeloid cells into cancer, high‐level expression of cancer cell‐derived chemokine CXCL16 increases infiltrating CD8+ and CD4+ T cells into cancer tissues, and correlates with a good prognosis. We discuss the conflicting biological effects of cancer cell‐derived chemokines on cancer progression, using CCL9 and CXCL16 as examples. (Cancer Sci 2007; 98: 1652–1658)

New method of preparing high-porosity rapidly saliva soluble compressed tablets using mannitol with camphor, a subliming material

Compressed tablets of a water-soluble material, prepared using mannitol, did not rapidly dissolve in water since it is difficult for water to penetrate into the tablets due to their low porosity. To increase the porosity of the tablets which are prepared by direct compression using mannitol, we developed a novel method whereby camphor, a subliming material, is removed by sublimation from compressed tablets prepared using a mixture of mannitol and camphor. A high porosity was achieved due to the formation of many pores where camphor particles previously existed in the compressed mannitol tablets prior to sublimation of the camphor. These compressed tablets which have high porosity (approximately 30%) rapidly dissolved within 15 s in saliva in the mouth. We developed a direct compression method for the preparation, using mannitol and camphor, of a meclizine (antidinic agent) tablet with high porosity which dissolves rapidly in saliva.

Chemokine receptor CXCR4 expression and prognosis in patients with metastatic prostate cancer

The chemokine receptor CXCR4 has been reported to be aberrantly expressed in human cancers and has also been shown to participate in the development of cancer metastasis. The present study was carried out to assess immunohistochemically the pattern of CXCR4 expression in patients with metastatic prostate cancer. We analyzed whether there may be an association between CXCR4 expression and prognosis. Fifty‐two patients who received hormonal therapy were enrolled. Specimens were obtained from transperineal needle biopsy before treatment, and were stained with antihuman CXCR4 antibody. We also evaluated the pathological grade, extent of bony metastasis, clinical response to hormonal therapy, and patient prognosis. CXCR4 was detected in 94.2% patients. Its expression showed no association with pathological grade, extent of bony metastasis, or clinical response to hormonal therapy. Patients with a high expression of CXCR4 in tumors had poorer cancer‐specific survival than those with low expression of CXCR4. CXCR4 expression is a useful prognostic factor for patients with metastatic prostate cancer treated with androgen‐withdrawal therapy. (Cancer Sci 2008; 99: 539–542)

High-Level Expression of Chemokine CXCL16 by Tumor Cells Correlates with a Good Prognosis and Increased Tumor-Infiltrating Lymphocytes in Colorectal Cancer

CXCL16 is a new member of the chemokine superfamily, which exists in a transmembrane as well as a soluble form. Its receptor CXCR6 is detected on CD4(+) T cells, CD8(+) T cells, and natural killer T cells. Here, we report a significant correlation of CXCL16 expression by tumor cells with the infiltration of T cells and prognosis in colorectal cancer (CRC). We first found that CXCL16 expression was consistently up-regulated more in tumor tissues than in normal mucosa derived from the same CRC patients. Four human CRC cell lines also expressed CXCL16 mRNA and secreted soluble CXCL16. We next examined the expression of CXCL16 and infiltration of lymphocytes in CRC specimens (n = 58) by immunohistochemistry. CRC patients with high levels of CXCL16 expression (n = 43) had higher levels of CD4(+) and CD8(+) tumor-infiltrating lymphocytes (TIL; P < 0.01) than those with low levels of CXCL16 expression (n = 15). Furthermore, the high CXCL16 expression group showed significantly better prognosis than the low CXCL16 expression group (P < 0.05). Collectively, our data suggest that the expression of CXCL16 by tumor cells enhances the recruitment of TILs, thereby bringing about a better prognosis in CRC. Thus, CXCL16 is a new prognostic biomarker and may be useful for the development of a more effective therapeutic strategy for CRC.

Blocking on the CXCR4/mTOR signalling pathway induces the anti-metastatic properties and autophagic cell death in peritoneal disseminated gastric cancer cells

Patients with advanced gastric carcinoma, especially peritoneal dissemination, have a poor prognosis even after any treatment. Chemokines are now known to play an important role in cancer growth and metastasis. We recently reported that the chemokine CXCL12 plays an important role in the development of peritoneal carcinomatosis from gastric carcinoma. In this study, we investigated signalling pathway involved in the peritoneal carcinomatosis induced by chemokine CXCL12. Akt was rapidly and strongly phosphorylated by chemokine CXCL12. CXCL12 also induced the activation of p70S6K (S6K) and eukaryotic initiation factor 4E binding protein 1 (4E-BP1) included in mammalian target of rapamycin (mTOR) pathways which are located downstream of Akt, resulting in enhancements of metastatic properties such as MMP production, cell migration and cell growth in peritoneal disseminated gastric cancer, NUGC4 cells. Furthermore, mTOR inhibitor rapamycin not only drastically inhibited migration and MMP production, but also induced type II programmed cell death, autophagic cell death. In the present study, we have shown for the first time that the mTOR pathway plays a central role in the development of peritoneal carcinomatosis, and blocking this pathway induces autophagic cell death in disseminated gastric cancer. Therefore, blocking on the CXCR4/mTOR signalling pathway may be useful for the future development of a more effective therapeutic strategy for gastric cancer involved in peritoneal dissemination.

RANKL-induced CCL22/macrophage-derived chemokine produced from osteoclasts potentially promotes the bone metastasis of lung cancer expressing its receptor CCR4

Chemokines are now known to play an important role in cancer growth and metastasis. Here we report that differentiating osteoclasts constitutively produce CCL22 (also called macrophage-derived chemokine) and potentially promote bone metastasis of lung cancer expressing its receptor CCR4. We first examined expression of chemokines by differentiating osteoclasts. CCL22 was selectively upregulated in osteoclast-like cells derived from RAW264.7 cells and mouse bone marrow cells upon stimulation with RANKL (receptor activator of nuclear factor-κB ligand). In addition, a human lung cancer cell line SBC-5 that efficiently metastasized to bone when intravenously injected into NK cell-depleted SCID mice was found to express CCR4. Stimulation of SBC-5 cells with CCL22 induced cell migration and also enhanced phosphorylation of protein kinase B/Akt and extracellular signal-regulated kinase (ERK). Furthermore, immunohistochemical analysis of bone metastasis lesions demonstrated close co-localization of tartrate-resistant alkaline phosphatase (TRAP)-positive osteoclasts expressing CCL22 and SBC-5 cells expressing CCR4. Collectively, these results suggest that osteoclasts may promote bone metastasis of cancer cells expressing CCR4 in the bone marrow by producing its ligand CCL22.

Prevention of Intrahepatic Metastasis by Curcumin in an Orthotopic Implantation Model

Curcumin has been shown to have potent anti-metastatic activity, however, its mechanism of action is still unclear. Here, we analyzed the anti-metastatic mechanism using hepatocellular carcinoma, CBO140C12 cells. Daily oral administration of curcumin suppressed intrahepatic metastasis in a dose-dependent manner, whereas the growth of implanted tumors was not affected. We next examined the effect of curcumin on several metastatic properties in vitro. Curcumin inhibited the invasion of tumor cells through Matrigel-coated filters and the production of MMP-9. In addition, curcumin significantly inhibited adhesion and haptotactic migration to fibronectin and laminin without affecting the expression of integrins on the cell surface. Furthermore, the formation of actin stress fibers was affected by treatment with curcumin. These results suggested that curcumin suppressed the intrahepatic metastasis mediated by the inhibiton of several metastatic properties, in which the functional alteration of cytoskeletal organization, at least in part, could play an important role.

Role of CX3CL1/Fractalkine in Osteoclast Differentiation and Bone Resorption

The recruitment of osteoclast precursors toward osteoblasts and subsequent cell-cell interactions are critical for osteoclast differentiation. Chemokines are known to regulate cell migration and adhesion. CX3CL1 (also called fractalkine) is a unique membrane-bound chemokine that has dual functions for cells expressing its receptor CX3CR1: a potent chemotactic factor in its soluble form and a type of efficient cell adhesion molecule in its membrane-bound form. In this paper, we demonstrate a novel role of CX3CL1 in osteoblast-induced osteoclast differentiation. We found that osteoclast precursors selectively expressed CX3CR1, whereas CX3CL1 is expressed by osteoblasts. We confirmed that soluble CX3CL1 induced migration of bone marrow cells containing osteoclast precursors, whereas immobilized CX3CL1 mediated firm adhesion of osteoclast precursors. Furthermore, a blocking mAb against CX3CL1 efficiently inhibited osteoclast differentiation in mouse bone marrow cells cocultured with osteoblasts. Anti-CX3CL1 also significantly suppressed bone resorption in neonatal mice by reducing the number of bone-resorbing mature osteoclasts. Collectively, CX3CL1 expressed by osteoblasts plays an important role in osteoclast differentiation, possibly through its dual functions as a chemotactic factor and adhesion molecule for osteoclast precursors expressing CX3CR1. The CX3CL1-CX3CR1 axis may be a novel target for the therapeutic intervention of bone resorbing diseases such as rheumatoid arthritis, osteoporosis, and cancer bone metastasis.

Inhibition of lymphangiogenesis-related properties of murine lymphatic endothelial cells and lymph node metastasis of lung cancer by the matrix metalloproteinase inhibitor MMI270

Based on a previous report on the effect of a matrix metalloproteinase (MMP) inhibitory compound, MMI270, in regulating tumor‐induced angiogenesis, as well as recent findings concerning functional correlations among tumor metastasis, angiogenesis and lymphangiogenesis, we investigated the anti‐metastatic efficacy of MMI270 in a murine model of lymph node metastasis of lung cancer, and analyzed whether this inhibitor could also regulate lymphangiogenesis‐related properties of murine lymphatic endothelial cells (LECs) and invasive properties of Lewis lung cancer (LLC) cells. The observation that MMI270 led to a significant decrease in the weight of tumor‐metastasized lymph nodes of mice led us to test its anti‐lymphangiogenic and anti‐invasive effects in vitro. Murine LECs were characterized by an in vitro tube formation assay, by semi‐quantitative RT‐PCR assay to examine the expression of mRNAs for flt‐4, Flk‐1, Tie‐1, Tie‐2, CD54/ICAM1, vWF, MMPs and uPA, and by western blotting to confirm the protein expression of flt‐4 and CD31/PECAM. This is the first report on the expression of MMP‐2, MMP‐9 and MT1‐MMP in murine LECs, as well as on the inhibition of their enzymatic activity, and of the invasive ability and tube‐forming property of LECs by an MMP inhibitor. Furthermore, MMI270 was shown to strongly inhibit the activity of MMP‐2 and ‐9 produced by LLC cells and the invasion of these cells through Matrigel. In summary, the present results indicate that MMI270, apart from its anti‐tumor angio‐genic application, might be useful as an anti‐metastatic drug, on the basis of its downregulatation of both the lymphangiogenesis‐related properties of LECs and the invasive properties of LLC cells in vitro. (Cancer Sci 2004; 95: 25–31)