Search

The use of conventional cytotoxic agents at metronomic schedules, alone or in combination with targeted agents or immunotherapy, is being explored as a promising anticancer strategy. We previously reported a potent antitumor effect of a single low-dose cyclophosphamide and interleukin-12 (IL-12) gene therapy against advanced gastrointestinal carcinoma, in mice. Here, we assessed whether the delivery of IL-12 by gene therapy together with metronomic cyclophosphamide exerts antitumor effects in a murine model of colorectal carcinoma. This combination therapy was able, at least in part, to reverse immunosuppression, by decreasing the number of regulatory T cells (Tregs) as well as of splenic myeloid-derived suppressor cells (MDSC s). However, metronomic cyclophosphamide plus IL-12 gene therapy failed to increase the number of tumor-infiltrating T lymphocytes and, more importantly, to induce a specific antitumor immune response. With respect to this, cyclophosphamide at a single low dose displayed a superior anticancer profile than the same drug given at a metronomic schedule. Our results may have important implications in the design of new therapeutic strategies against colorectal carcinoma using cyclophosphamide in combination with immunotherapy. Fil: Malvicini, Mariana. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; Argentina Fil: Alaniz, Laura Daniela. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; Argentina Fil: Bayo Fina, Juan Miguel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; Argentina Fil: García, Mariana Gabriela. Universidad Austral; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina Fil: Piccioni, Flavia Valeria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; Argentina Fil: Fiore, Esteban Juan. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; Argentina Fil: Atorrasagasti, María Catalina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; Argentina Fil: Aquino, Jorge Benjamin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; Argentina Fil: Matar, Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Rosario. Facultad de Ciencias Medicas. Instituto de Genetica Experimental; Argentina Fil: Mazzolini Rizzo, Guillermo Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Austral; Argentina

The combination of a single low dose of cyclophosphamide (Cy) with the adenovirus-mediated gene transfer of interleukin-12 (AdIL-12) might represent a successful therapy for experimental gastrointestinal tumors. This approach has been proven to revert immunosuppressive mechanisms elicited by cancer cells and to synergistically promote antitumor immunity. In addition, this therapeutic regimen has been shown to be more efficient in achieving complete tumor regressions in mice than the application of a metronomic schedule of Cy plus AdIL-12.

Interaction between hyaluronic acid (HA) and CD44 has been considered a key event in tumor invasion and metastasis. HA is a linear, high molecular weight glycosaminoglycan in its native state, but fragmented low molecular forms are found at sites ofneoplastic or inflammatory infiltrates. Both high and low molecular weights HA are involved in diverse biological functions. In this study, we used two clonal variants of a T cell murine lymphoma designated LBLa and LBLc. These cell lines were found to differ in their in vivo and in vitro growth rates. LBLa grew faster and exhibited an enhanced invasive capacity as compared to LBLc. In contrast, cell lines did not differ in the expression of surface markers (CD8, CD24, CD25, CD44, and CD18), or in their capacity to bind HA. However, LBLa cells exhibited higher capacity to migrate to low molecular weight HA than did LBLc. Migration was mediated by CD44 since it was abrogated by anti-CD44 monoclonal antibody as well as by hyaluronidase. We suggest that interaction between CD44 and low molecular weight HA may trigger migration mechanisms in LBLa cells, thus contributing to enhanced invasive cell capacity.