Metastatic Potential Of Human Cancer Research Articles

CD6 is a target for cancer immunotherapy.

Limitations of checkpoint inhibitor cancer immunotherapy include induction of autoimmune syndromes and resistance of many cancers. Since CD318, a novel CD6 ligand, is associated with the aggressiveness and metastatic potential of human cancers, we tested the effect of an anti-CD6 monoclonal antibody, UMCD6, on killing of cancer cells by human lymphocytes. UMCD6 augmented killing of breast, lung, and prostate cancer cells through direct effects on both CD8+ T cells and NK cells, increasing cancer cell death and lowering cancer cell survival in vitro more robustly than monoclonal antibody checkpoint inhibitors that interrupt the programmed cell death 1 (PD-1)/PD-1 ligand 1 (PD-L1) axis. UMCD6 also augmented in vivo killing by human peripheral blood lymphocytes of a human breast cancer line xenotransplanted into immunodeficient mice. Mechanistically, UMCD6 upregulated the expression of the activating receptor NKG2D and downregulated expression of the inhibitory receptor NKG2A on both NK cells and CD8+ T cells, with concurrent increases in perforin and granzyme B production. The combined capability of an anti-CD6 monoclonal antibody to control autoimmunity through effects on CD4+ lymphocyte differentiation while enhancing killing of cancer cells through distinct effects on CD8+ and NK cells opens a potential new approach to cancer immunotherapy that would suppress rather than instigate autoimmunity.

Nm23‐H1 modulates the activity of the guanine exchange factor Dbl‐1

Cytoskeleton rearrangement is necessary for tumor invasion and metastasis. Cellular molecules whose role is to regulate components of the cytoskeletal structure can dictate changes in cellular morphology. One of these molecules is the suppressor of tumor metastasis Nm23-H1. The level of Nm23-H1 expression has been linked to the invasiveness and metastatic potential of human cancers including melanoma and breast cancer. In this report, we demonstrate an interaction between the suppressor of tumor metastasis Nm23-H1, and Dbl-1, an oncoprotein which is associated with guanine exchange and belongs to a family of Guanine Exchange Factors (GEF). Nm23-H1 also was shown to bind pDbl which is the proto-oncoprotein of Dbl. Interestingly, the interaction between Nm23-H1 and Dbl-1 rescues the suppression of the cell motility activity Nm23-H1. Moreover, this interaction results in loss of the ability of the Dbl-1 oncoprotein to function as a GEF for the critical Rho-GTPase family member Cdc42. The loss of GTP loading onto Cdc42 resulted in a dramatic reduction in adhesion stimulated ruffles and suggests that Nm23-H1 can negatively regulate cell migration and tumor metastasis by modulating the activity of Cdc42 through direct interaction with Dbl-1.

The suppressor of metastasis Nm23-H1 interacts with the Cdc42 Rho family member and the pleckstrin homology domain of oncoprotein Dbl-1 to suppress cell migration

Tumor invasion and metastasis is regulated by a number of cellular molecules known to be involved in signaling and cytoskeletal rearrangement. One of these molecules is the suppressor of tumor metastasis Nm23-H1 which linked to invasiveness and metastatic potential of human cancers. Nm23-H1 expression is down-regulated in human melanoma and invasive breast carcinoma. Recent studies have shown an association between the Nm23-H1 and oncoprotein Dbl-1 which is associated with guanine exchange and belongs to a family of Guanine Exchange Factors (GEF). In this report we show a direct interaction in vitro and in human B cells and specifically identified the pleckstrin homology domain of Dbl-1 as the domain which binds to Nm23-H1. Furthermore, Nm23-H1 and Dbl-1 colocalized in the cytoplasm of COS-7 cells when expressed exogenously and showed predominant signals at the periphery of the cells particularly at the plasma membrane. Interestingly, Dbl-1 and Cdc42 expression rescued the suppressive activities of Nm23-H1 in cell migration assays. We show that Cdc42 a regulatory protein involved in cytoskeletal reorganization, cell growth and development can bind to Nm23-H1 and the kinase deficient mutant H118F but only weakly to the mutant P96S which lacks the ability to suppress cell migration and metastasis. Cdc42 also colocalized with Nm23-H1 and the Dbl-1 proteins as specific punctate signals in the cytoplasm and at the cell membrane. Nm23-H1 also lead to the reduction in membrane ruffles and protuberances when expressed with Dbl-1 and Cdc42. Supprisingly, Nm23-H1 interacted with Cdc42 as well as Rac1 but somewhat weaker with RhoA. These studies suggests that Nm23-H1 can negatively regulate cell migration and tumor metastasis by modulating the activity of Cdc42 and possibly other Rho family members through interaction with Dbl-1.

Monitoring E-selectin-mediated adhesion using green and red fluorescent proteins

Accumulating evidence suggests that E-selectin, which is physiologically involved in leukocyte recruitment during inflammation, plays an important role in the early stages of tumor cell interactions with vessel walls and contributes to the hematogenous spreading of cancer cells. Therapy designed to block this key step may provide an effective anti-inflammatory and anti-metastatic treatment. It is therefore critical to establish a safe, rapid and sensitive E-selectin adhesion assay. In this regard, we propose a simple and highly sensitive adhesion system based on CHO cells permanently co-expressing E-selectin and the enhanced green fluorescent protein EGFP or the red fluorescent protein DsRed2. This is an inverted adhesion assay in which tumor cells are maintained intact while fluorescent cells expressing E-selectin and EGFP (or DsRed2) are added to them. Adherent cells are then quantified by three different fluorescence-based techniques including spectrofluorimetry, ELISA-type cytofluorimetry and fluorescence microscopy coupled to digital image quantification. In this assay, a battery of cell lines can be analysed at once since only one cell line (fluorescent E-selectin-expressing cells) needs to be harvested. We used this approach to analyze a number of E-selectin-specific binding parameters of intestinal cancer cells in comparison with adhesion to activated endothelial cells or to plastic dishes coated with recombinant E-selectin. Besides the possibility of analyzing a battery of cell lines at once, this assay might be suitable for screening anti-metastatic compounds and could provide valuable information on the metastatic potential of human cancers.

Urokinase plasminogen activator, a potent marker of metastatic potential in human cancer

Urokinase plasminogen activator, a potent marker of metastatic potential in human cancer

Expression of metastasis-associated genes h-mts1 (S100A4) and nm23 in carcinoma of breast is related to disease progression.

The murine 18A2/mts1 and its human homolog h-mts1 (S100A4), encoding a Ca2+-binding protein belonging to the S-100 family, are associated with high invasive and metastatic potentials of murine tumors, human tumor cell lines in vitro, and human tumors growing as xenografts. The nm23 is a putative metastasis-suppressor gene whose expression has been found to correlate inversely with the metastatic potential of some forms of human cancer. The products of both human genes alter cytoskeletal dynamics, with antagonistic effects. In view of the equivocal association of nm23 with the metastatic potential of human cancer, we suspected that the relative expression of h-mts1 and nm23 might reflect tumor progression more accurately than either of them alone. We describe here the expression of these genes in infiltrating ductal carcinomas of the breast and show that high h-mts1 expression is associated with metastatic spread to the regional lymph nodes. The expression of nm23 on its own did not show a statistically significant inverse correlation with nodal spread. However, the expression status of the two genes, taken together, correlated strongly with the occurrence of nodal metastases. Breast cancers with no detectable expression of h-mts1 were found to be estrogen and progesterone receptor positive. Expression of h-mts1 was not related to tumor differentiation. The clinical data, together with the state of expression of steroid receptors and the expression levels of h-mts1 and nm23 genes, were analyzed using artificial neural networks for accuracy in predicting nodal spread of the carcinomas. These analyses support the conclusion that, overall, h-mts1 expression appears to be associated with and indicative of more aggressive disease. Complemented with nm23, h-mts1 could provide a powerful marker of breast cancer prognosis.

Actinin-4, a novel actin-bundling protein associated with cell motility and cancer invasion.

Regulation of the actin cytoskeleton may play a crucial role in cell motility and cancer invasion. We have produced a monoclonal antibody (NCC- Lu-632, IgM, k) reactive with an antigenic protein that is upregulated upon enhanced cell movement. The cDNA for the antigen molecule was found to encode a novel isoform of nonmuscle alpha-actinin. This isoform (designated actinin-4) was concentrated in the cytoplasm where cells were sharply extended and in cells migrating and located at the edge of cell clusters, but was absent from focal adhesion plaques or adherens junctions, where the classic isoform (actinin-1) was concentrated. Actinin-4 shifted steadily from the cytoplasm to the nucleus upon inhibition of phosphatidylinositol 3 kinase or actin depolymerization. The cytoplasmic localization of actinin-4 was closely associated with an infiltrative histological phenotype and correlated significantly with a poorer prognosis in 61 cases of breast cancer. These findings suggest that cytoplasmic actinin-4 regulates the actin cytoskeleton and increases cellular motility and that its inactivation by transfer to the nucleus abolishes the metastatic potential of human cancers.