Anti-idiotype x anti-LFA-1 bispecific antibodies inhibit metastasis of B cell lymphoma

Role of adhesion molecules in cancer and targeted therapy

Adhesion molecules mediate cell-to-cell and cell-to-extracellular matrix interactions and transmit mechanical and chemical signals among them. Various mechanisms deregulate adhesion molecules in cancer, enabling tumor cells to proliferate without restraint, invade through tissue boundaries, escape from immune surveillance, and survive in the tumor microenvironment. Recent studies have revealed that adhesion molecules also drive angiogenesis, reshape metabolism, and are involved in stem cell self-renewal. In this review, we summarize the functions and mechanisms of adhesion molecules in cancer and the tumor microenvironment, as well as the therapeutic strategies targeting adhesion molecules. These studies have implications for furthering our understanding of adhesion molecules in cancer and providing a paradigm for exploring novel therapeutic approaches.

ICAM2 is related to good prognosis in dendritic cell immunotherapy for cancer

Objective: To evaluate the behavior of adhesion molecules ICAM-1 and ICAM-2 in dendritic cell (DC) immunotherapy. Materials & methods: 88 female Balb/c mice were divided into experimental groups. Tumors and lymph nodes were evaluated 7 and 14 days after immunotherapy. Results: Higher mean fluorescence intensity of ICAM-1 in the lymph nodes and tumors in the tumor group at 14 days was observed. Higher mean fluorescence intensity of ICAM-2 in the tumor DC vaccine group was observed after 14 days. A positive correlation was observed in the lymph nodes with ICAM-1 against tumoral volume in the tumor group. A negative correlation was found between ICAM-2 and tumoral volume in the lymph nodes of the tumor group. Conclusion: An increase in ICAM-2 in tumor DC vaccine and a decrease in ICAM-1 suggests the DC vaccine positively influences the immune system and that ICAM-2 could be a marker of good prognosis.

CCR7 in Blood Cancers - Review of Its Pathophysiological Roles and the Potential as a Therapeutic Target

According to the classical paradigm, CCR7 is a homing chemokine receptor that grants normal lymphocytes access to secondary lymphoid tissues such as lymph nodes or spleen. As such, in most lymphoproliferative disorders, CCR7 expression correlates with nodal or spleen involvement. Nonetheless, recent evidence suggests that CCR7 is more than a facilitator of lymphatic spread of tumor cells. Here, we review published data to catalogue CCR7 expression across blood cancers and appraise which classical and novel roles are attributed to this receptor in the pathogenesis of specific hematologic neoplasms. We outline why novel therapeutic strategies targeting CCR7 might provide clinical benefits to patients with CCR7-positive hematopoietic tumors.

Cell adhesion in cancer: Beyond the migration of single cells

Homeostasis in healthy tissues strongly relies on cell-to-cell adhesion and cell-to-extracellular matrix interactions. For instance, normal epithelial cells maintain tissue structure by adhering to each other and to the extracellular matrix. The proteins that mediate these distinct interactions are collectively called cell adhesion molecules and are divided into four major groups: cadherins, integrins, selectins, and immunoglobulins. They not only physically anchor cells, but also critically integrate signaling between the extracellular microenvironment and cells. These signals include biochemical cues, as adhesion proteins can both act as ligand-activated receptors and activate mechanotransduction triggered by changes in the physical environment. Molecular mechanisms related to cell adhesion signaling have been extensively studied, especially because mutations and changes in expression of these proteins, particularly cadherins and integrins, are frequently associated with diseases ranging from developmental intellectual disability to cancer. In fact, two major hallmarks of cancer, loss of cell-to-cell adhesion and anchorage-independent growth, are both dependent on cell adhesion molecules. Despite many studies elucidating the relationships between malignant transformation and metastasis and cellular adhesion processes, several areas still await exploration. Here, we highlight recently discovered roles of adhesion molecules in collective cancer cell migration and discuss the utility of three-dimensional models in studying cell-cell adhesion. We also describe recent therapeutic approaches targeting adhesion molecules.

Cell Adhesion Molecules and Their Roles and Regulation in the Immune and Tumor Microenvironment

The immune system and cancer have a complex relationship with the immune system playing a dual role in tumor development. The effector cells of the immune system can recognize and kill malignant cells while immune system-mediated inflammation can also promote tumor growth and regulatory cells suppress the anti-tumor responses. In the center of all anti-tumor responses is the ability of the immune cells to migrate to the tumor site and to interact with each other and with the malignant cells. Cell adhesion molecules including receptors of the immunoglobulin superfamily and integrins are of crucial importance in mediating these processes. Particularly integrins play a vital role in regulating all aspects of immune cell function including immune cell trafficking into tissues, effector cell activation and proliferation and the formation of the immunological synapse between immune cells or between immune cell and the target cell both during homeostasis and during inflammation and cancer. In this review we discuss the molecular mechanisms regulating integrin function and the role of integrins and other cell adhesion molecules in immune responses and in the tumor microenvironment. We also describe how malignant cells can utilize cell adhesion molecules to promote tumor growth and metastases and how these molecules could be targeted in cancer immunotherapy.

Role of LFA-1 and ICAM-1 in Cancer

The lymphocyte function-associated antigen-1 (LFA-1) (also known as CD11a/CD18 and α_Lβ₂), is just one of many integrins in the human body, but its significance is derived from its exclusive presence in leukocytes. In this review, we summarize the studies relating LFA-1 and its major ligand ICAM-1 (or CD54) with cancer, through the function of lymphocytes and myeloid cells on tumor cells. We consider how LFA-1 mediates the interaction of leukocytes with tumors and the role of ICAM-1 in tumor dynamics, which can be independent of its interaction with LFA-1. We also offer a more detailed examination of the role of LFA-1 within B-cell chronic lymphocytic leukemia. Finally, we discuss the role that exosomes harboring LFA-1 play in tumor growth and metastasis.

Disruption of tumour-host communication by downregulation of LFA-1 reduces COX-2 and e-NOS expression and inhibits brain metastasis growth

Over 20% of cancer patients will suffer metastatic spread to the brain, and prognosis remains poor. Communication between tumour cells and host tissue is essential during metastasis, yet little is known of the processes underlying such interactions in the brain.Here we test the hypothesis that cross-talk between tumour cells and host brain cells, through tumour cell leukocyte function associated protein-1 (LFA-1), is critical in metastasis development. Temporal expression of LFA-1 and its major ligand intercellular adhesion molecule-1 (ICAM-1) was determined in two different mouse models of brain metastasis. Marked upregulation of both proteins was found, co-localising with astrocytes, microglia and tumour cells themselves. Silencing of LFA-1 expression in MDA231Br-GFP cells prior to intracerebral injection resulted in > 70% reduction in tumour burden compared to control MDA231Br-GFP cells (p < 0.005, n = 5). Subsequent qRT-PCR analysis of brain tissue revealed significant reductions in COX-2, VEGF and eNOS from host brain tissue, but not tumour cells, in mice injected with LFA-1 knockdown cells (p < 0.0001, n = 5). Finally, expression of both LFA-1 and ICAM-1 was demonstrated in human brain metastasis samples.The results of this study suggest LFA-1 as a new target in brain metastasis therapy and highlight the potential synergy with current anti-COX-2 and anti-NOS therapies.

CD7 promotes extramedullary involvement of the B-cell acute lymphoblastic leukemia line Tanoue by enhancing integrin β2-dependent cell adhesiveness

Extramedullary involvement (EMI) is a factor that defines prognosis of acute lymphoblastic leukemia; however, the molecular mechanism(s) remain elusive. Here, we show that CD7 promotes EMI of the human B-cell acute lymphoblastic leukemia cell line Tanoue. The Tanoue cell line expressing firefly luciferase, Luc-Tanoue, was transplanted into non-obese diabetic/severe combined immunodeficient mice, and cells infiltrated into the brain were cultured ex vivo. This process was repeated 4 times to obtain the highly invasive line Luc-Tanoue-F4. Comparison of the global gene expression signatures of Luc-Tanoue-F4 and Luc-Tanoue indicated that the CD7 gene showed the largest increase in expression among EMI-related genes in Luc-Tanoue-F4 cells. Overexpression of CD7 in Tanoue enhanced cell invasiveness. Among cell migration, proliferation, adhesion and protease activity, only cell adhesiveness showed enhancement in Luc-Tanoue-F4. Expression of the intracellular domain, but not the extracellular domain, of CD7 enhanced cell adhesiveness. Luc-Tanoue-F4 showed a higher level of integrin β2 expression; overexpression of CD7 induced the expression of integrin β2 in Luc-Tanoue. These results show that CD7 induces integrin β2 and enhances cell adhesiveness and invasiveness in Tanoue cells. This study highlights the role of the CD7/integrin β2 axis as a critical pathway in the process of EMI of human B-cell acute lymphoblastic leukemia.

Anti-LFA-1 antibodies enhance metastasis of ocular lymphoma to the brain and contralateral eye

Previously we demonstrated that intraperitoneal (IP) inoculation of Rev-2-T-6 mouse lymphoma into syngeneic Balb/c hosts resulted in brain metastasis, migration along the optic nerve sheath, and ocular infiltration. In a second model: intravitreal inoculation of Rev-2-T-6 cells, the developing lymphoma was largely confined within the eye, seldom breaching the retinal pigment epithelium to reside in the choroid and sclera. There was no retrograde infiltration into the brain. Here, we describe a third, complementary model, whereby intravitreal inoculation of Rev-2-T-6 cells into Balb/c mice, followed by repeated IP inoculations of anti-LFA-1/CD11a monoclonal antibodies, results in extensive infiltration of the choroid, sclera, conjunctiva, eyelids and orbit. Furthermore, the lymphoma cells metastasize along the optic nerve sheath into the brain, and through the contralateral optic nerve tract into the contralateral eye. There is no systemic involvement of the lymphoma. Furthermore, anti-LFA-1 treatment results in elevated levels of serum anti-Rev-2-T-6 antibodies. Inoculation of Rev-2-T-6 cells into the vitreous of severe combined immune deficient mice demonstrates a course of clinical signs and histopathological findings similar to those in immune-competent mice treated with anti-LFA-1 antibodies, including invasion of the contralateral eye. Taken together, these findings suggest that confinement of Rev-2-T-6 lymphoma cells to the eye depends on active immune surveillance using a population of effector cells expressing the cell surface integrin LFA-1. Impairing this protection enhances tumor aggressiveness within the eye, and the likelihood of early retrograde lymphoma metastasis into the brain and the contralateral eye.

Bispecific antibodies for cancer therapy

Bispecific antibodies, in contrast to conventional monoclonal antibodies, can bind simultaneously two different antigens. Taking advantage of this virtue, they are mostly designed for immune effector cell redirection to tumors and for radionuclide pretargeting to tumors. Bispecific antibodies of the first generation were produced by chemical cross-linking or cell-fusion technologies. More recently, the application of genetic engineering technologies gave rise to numerous formats of bispecific antibody fragments and whole IgG molecules. Because bispecific antibodies enable therapeutic strategies that are not possible with conventional monoclonal antibodies, they attract strong interest. Several bispecific antibody formats have already shown clinical efficacy in cancer patients, catalyzing efforts to translate the imaginative bispecific antibody concepts into effective therapies.

Colon carcinoma cell interaction with liver sinusoidal endothelium inhibits organ-specific antitumor immunity through interleukin-1-induced mannose receptor in mice

Mannose receptor (ManR)-mediated liver sinusoidal endothelial cell (LSEC) endocytosis plays a role in antigen presentation and innate immunity, but its role in hepatic metastasis is unknown. We studied ManR-mediated endocytosis during C26 colorectal cancer cell interaction with LSECs and its implications in metastasis. Uptake of labeled ManR ligands (mannan and ovalbumin) and immunohistochemistry were used to study ManR endocytosis and expression. Several interleukin (IL)-1 inhibitors and the cyclooxygenase-2 (COX-2) inhibitor celecoxib were used to analyze the role of IL-1 and COX-2 in ManR regulation. Anti-mouse ManR antibodies and ManR knockout (ManR(-/-)) mice were used to identify ManR-dependent mechanisms during antitumor immune response of liver sinusoidal lymphocytes (LSLs) interacting with tumor-activated LSECs. ManR expression and endocytosis increased in tumor-activated LSECs through a two-step mechanism: (1) Release of COX-2-dependent IL-1-stimulating factors by lymphocyte function-associated antigen-1-expressing C26 cells in response to intercellular adhesion molecule-1 (ICAM-1), which was expressed and secreted by tumor-activated LSECs; and (2) widespread up-regulation of ManR in LSECs through tumor-induced IL-1. In addition, LSLs that had interacted with tumor-activated LSECs in vivo decreased their antitumor cytotoxicity and interferon (IFN)-gamma secretion while they increased IL-10 release ex vivo. IFN-gamma/IL-10 ratio also decreased in the hepatic blood from tumor-injected mice. Immunosuppressant effects of tumor-activated LSECs on LSLs were abrogated in both LSECs from ManR(-/-) mice and tumor-activated LSECs given anti-mouse ManR antibodies.

CONCLUSION

ICAM-1-induced tumor COX-2 decreased antitumor activity during hepatic metastasis through IL-1-induced ManR. ManR constituted a common mediator for prometastatic effects of IL-1, COX-2, and ICAM-1. A rise in hepatic IFN-gamma/IL-10 ratio and antitumor cytotoxicity by way of ManR blockade is consistent with the antimetastatic effects of IL-1, COX-2, and ICAM-1 inhibitors. These data support ManR and ManR-stimulating factors as targets for hepatic colorectal metastasis therapy.

Synergistic effect of dendritic cell vaccination and anti-CD20 antibody treatment in the therapy of murine lymphoma

Indolent B-cell lymphomas are characterized by repeated remissions and relapses with most patients eventually dying of the disease. Although combination treatments with chemotherapy and the anti-CD20 antibody rituximab improved duration of remissions and overall survival, the disease is essentially incurable. Thus, novel therapeutic approaches are needed. One such approach is active immunization with dendritic cells (DCs). Given that rituximab depletes patients of normal B cells, optimal vaccination strategies for rituximab-treated patients require induction of effector T cells. We have previously demonstrated in a murine model that idiotype (Id)-keyhole limpet hemocyanin-pulsed DCs induced Id-reactive CD8 T cells and protection against tumor challenge in the absence of anti-Id antibodies. On the basis of these results, we investigated vaccination in a therapeutic model, in which mice carrying advanced tumors of the highly aggressive 38C-13 lymphoma were treated with chemotherapy and anti-CD20 antibodies combined with a DC-based vaccine. As a rule, cytoreduction by cyclophosphamide was required in each regimen of combination treatment, and vaccination with tumor cell-loaded DCs was more effective than vaccination with Id-keyhole limpet hemocyanin-loaded DCs. We demonstrated that under conditions of large primary tumors that had already spread to lymph nodes, when anti-CD20 antibody treatment showed minimal effect and DC vaccination had no effect, synergism between anti-CD20 antibodies and DC vaccines resulted in significant long-term survival that did not involve active antitumor antibody production. Combination treatments including tumor cell-loaded DC vaccines may therefore provide a strategy for enhancing the potency of therapy in rituximab-treated patients.

Three-dimensional growth as multicellular spheroid activates the proangiogenic phenotype of colorectal carcinoma cells via LFA-1-dependent VEGF: implications on hepatic micrometastasis

Background

The recruitment of vascular stromal and endothelial cells is an early event occurring during cancer cell growth at premetastatic niches, but how the microenvironment created by the initial three-dimensional (3D) growth of cancer cells affects their angiogenesis-stimulating potential is unclear.

Methods

The proangiogenic profile of CT26 murine colorectal carcinoma cells was studied in seven-day cultured 3D-spheroids of <300 μm in diameter, produced by the hanging-drop method to mimic the microenvironment of avascular micrometastases prior to hypoxia occurrence.

Results

Spheroid-derived CT26 cells increased vascular endothelial growth factor (VEGF) secretion by 70%, which in turn increased the in vitro migration of primary cultured hepatic sinusoidal endothelium (HSE) cells by 2-fold. More importantly, spheroid-derived CT26 cells increased lymphocyte function associated antigen (LFA)-1-expressing cell fraction by 3-fold; and soluble intercellular adhesion molecule (ICAM)-1, given to spheroid-cultured CT26 cells, further increased VEGF secretion by 90%, via cyclooxygenase (COX)-2-dependent mechanism. Consistent with these findings, CT26 cancer cells significantly increased LFA-1 expression in non-hypoxic avascular micrometastases at their earliest inception within hepatic lobules in vivo; and angiogenesis also markedly increased in both subcutaneous tumors and hepatic metastases produced by spheroid-derived CT26 cells.

Conclusion

3D-growth per se enriched the proangiogenic phenotype of cancer cells growing as multicellular spheroids or as subclinical hepatic micrometastases. The contribution of integrin LFA-1 to VEGF secretion via COX-2 was a micro environmental-related mechanism leading to the pro-angiogenic activation of soluble ICAM-1-activated colorectal carcinoma cells. This mechanism may represent a new target for specific therapeutic strategies designed to block colorectal cancer cell growth at a subclinical micrometastatic stage within the liver.

Anti-idiotype x anti-CD44 bispecific antibodies inhibit invasion of lymphoid organs by B cell lymphoma

The demonstration that Abs to adhesion molecules can block tumor metastasis suggested their use for therapy. However, such Abs affect nonmalignant cells as well. To circumvent this adverse effect, we proposed the use of bispecific Abs that bind simultaneously to an adhesion receptor and to a tumor-specific Ag. Such bifunctional Abs bind more avidly to tumor cells that coexpress both target Ags than to normal cells. The Id of the surface Ig of malignant B lymphocytes is a tumor-specific Ag. Therefore, we produced bispecific Abs with specificity to the adhesion molecule, CD44, and to an idiotypic determinant of the murine B cell lymphoma, 38C-13. These anti-Id x anti-CD44 bispecific Abs blocked 38C-13 cell adhesion to hyaluronic acid, while not affecting adhesion of Id-negative cells. In vivo studies demonstrated that the bispecific Abs inhibited lymphoma cell dissemination to the lymph nodes, bone marrow, and spleen, and prolonged survival of tumor-bearing mice. Migration of 38C-13 cells to the lymphoid organs was inhibited by the bispecific Abs. Thus, the bispecific Ab-mediated reduction in metastasis resulted, at least in part, from reduced homing to these organs. In contrast to anti-CD44 monospecific Abs, the anti-Id x anti-CD44 bispecific Abs did not affect immune responses such as delayed-type hypersensitivity. Hence, bispecific Abs against adhesion molecules and tumor-specific Ags may selectively block tumor metastasis in a way which may leave at least part of the immune system intact.