CD44H participates in the intrahepatic growth of murine colon 26 adenocarcinoma cells

Hyaluronan network: a driving force in cancer progression

Hyaluronan is one of the most abundant macromolecules of the extracellular matrix and regulates several physiological cell and tissue properties. However, hyaluronan has been shown to accumulate together with its receptors in various cancers. In tumors, accumulation of hyaluronan system components (hyaluronan synthesizing/degrading enzymes and interacting proteins) associates with poor outcomes of the patients. In this article, we review the main roles of hyaluronan in normal physiology and cancer, and further discuss the targeting of hyaluronan system as an applicable therapeutic strategy.

Hyaluronic acid stimulates tumor-cell proliferation at wound sites

BACKGROUND

For EMR, the submucosal injection of sodium hyaluronate has become popular, because this substance creates a more prominent and longer-lasting mucosal protrusion than normal saline solution. However, the effects of sodium hyaluronate on tumor growth at wound sites remain unclear.

METHODS

For these experiments, a murine model with artificial wounds was used. Forty mice were randomly divided into two groups according to the substance to be injected into a wound: a sodium hyaluronate group and a control group. Tumors were created by inoculation of transplantable adenocarcinoma cell line colon 26. Two weeks later, the size, weight, proliferating cell nuclear antigen-labeling index, and CD44 expression of the subcutaneous tumors were compared between the two groups of mice.

RESULTS

There were significantly greater increases in the growth and the weight of subcutaneous tumors in the sodium hyaluronate group compared with the control group. The PCNA-labeling index of cancer cells also was higher in the sodium hyaluronate group. Immunohistochemistry and Western blot analysis demonstrated that the CD44 protein expression of cancer cells was higher in the sodium hyaluronate group vs. the control group.

CONCLUSIONS

In this study, sodium hyaluronate enhanced both tumor growth and CD44 expression of cancer cells at wound sites, suggesting that the use of sodium hyaluronate for EMR might stimulate the growth of residual tumor cells.

Anti-CD44 monoclonal antibody (IM7) induces murine systemic shock mediated by platelet activating factor

The cell adhesion molecule CD44 plays an important role in progression of autoimmune diseases or cancer. Administration of anti-CD44 monoclonal antibodies (mAbs) have been reported to have anti-inflammatory or anti-cancer activity. However, our evidence shows that intravenous administration of the anti-CD44 IgG2b mAb IM7 induces systemic shock in mice. To examine the character of systemic shock, the cutaneous excess vascular permeability was evaluated. Administered mAb markedly increased vascular permeability but its F(ab')(2) fragments did not induce a reaction. The platelet-activating factor (PAF) specific antagonist Y-24180 was effective in preventing IM7-induced extravasation, whereas anti-histaminergic and anti-serotonergic agents were not. Y-24180 also ameliorated hematocrit elevation and hypotension in mice treated with IM7. These results indicate that IM7-induced systemic shock is mediated by PAF. Because IM7 also binds human CD44, anti-CD44 immunotherapy using IM7 may be applied to the clinical treatment of autoimmune diseases or cancer. This study describes potential triggering pathways for shock that must be avoided through modification of the immunotherapy.

Introduction of antisense CD44S CDNA down-regulates expression of overall CD44 isoforms and inhibits tumor growth and metastasis in highly metastatic colon carcinoma cells

We created antisense CD44 transfectants using LS174T, a colon adenocarcinoma cell line and assessed the effects of overall CD44 down-regulation on colorectal tumor growth and metastasis. The expression of antisense CD44s (the standard form of CD44) cDNA markedly inhibited the overall expression of CD44 variants. In vitro studies showed a significantly reduced ability of the stable antisense transfectants (LS174TAS1 and LS174TAS2) to bind hyaluronate and osteopontin, ligands for CD44. These cells developed tumors more slowly than controls (parental LS174T and mock transfectants) when the cells were subcutaneously injected into SCID mice. However, in vitro proliferation assays demonstrated no significant difference between the antisense transfectants and the controls on a hyaluronate-coated surface, suggesting the participation of ligands other than hyaluronate in tumor growth in vivo. Intrasplenic injection of parental LS174T cells produced colonies in the liver in 10 of 11 mice, whereas mice injected with the antisense transfectants were completely free of metastasis. In peritoneal dissemination, the weight of nodules and amount of ascites were significantly reduced in LS174TAS1 and AS2 compared with the controls. In vitro adhesion assays between the transfectants or controls and human peritoneal mesothelial cells revealed that the binding of LS174T cells to mesothelial cells was partly mediated by CD44-hyaluronate interaction. These data suggest that CD44-hyaluronate interaction plays a crucial role in peritoneal dissemination in colorectal carcinoma. The results of our study demonstrate the possible application of antisense CD44s to the treatment of colorectal carcinoma.