Immune reactivity during the growth of a murine lung adenocarcinoma: evaluation of paraneoplastic syndrome development.

The purpose of this study was to investigate if specific immune responses were present in mice bearing a lung adenocarcinoma that presents paraneoplastic syndromes during tumor evolution. Leukocytosis, mainly due to polymorphonuclear leukocytes, was found from day 15 of tumor growth. Delayed type hypersensitivity response and increased interleukin-6 (IL-6) serum levels were observed along tumor growth. Concomitant immunity, specific rejection of a second inoculum and in vitro specific cytotoxicity occurred at 20 days of implant. In advanced stages of tumor evolution impaired cytotoxicity, accompanied by a great increase of IL-6 in serum, were observed. Role of polymorphonuclear leukocytes and IL-6 overproduction as responsible for immune dysregulation and paraneoplastic syndromes are discussed.

A synthetic, nitrogenated antimetastatic and anti-angiogenic compound with low toxicity in vivo.

The design of more effective therapies for metastatic disease involves development of new compounds able to specifically block the malignant process. We demonstrated previously that a new synthetic nitrogenated compound 3'-1-chloroethyl-2,3-dihydro-1H-imidazo-(2, 1-i)-purine-4-ium-7-yl-3'-deoxy-1',5', 6'-tri-O-(methylsulfonyl)-muco-inositol chloride (DIC) had an anti-proliferative activity on tumor cells in vitro. In the present work we demonstrate that DIC induces apoptosis on the LM3 murine mammary adenocarcinoma cell line in vitro and has anti-angiogenic activity in vivo. We also evaluated toxicity, biodistribution and anti-neoplastic properties of DIC in vivo. Toxicity studies allowed us to establish the LD50 (750 mg/kg body weight). Administration of 250 mg/kg/day (LD10) for 6 days did not cause overt toxic effects. Biodistribution assays revealed that DIC was rapidly eliminated (60% at t=10 min), although it accumulated in tumor tissue at higher concentrations than in other tissues. Daily s.c. treatment with DIC (LD10) for 24 days significantly reduced the number of spontaneous lung metastases. These results suggest that DIC has the ability of impairing the metastatic development by inhibiting angiogenesis and inducing apoptosis on tumor cells.

Spontaneous murine lung adenocarcinoma (P07): A new experimental model to study paraneoplastic syndromes of lung cancer.

We report the histological and biological behavior characteristics of a lung tumor (P07) that arose spontaneously in a Balb/c mouse. P07 is a moderately to poorly differentiated adenocarcinoma that secretes granulocyte-macrophage colony stimulating factor (GM-CSF) in culture supernatants. This tumor presents some paraneoplastic syndromes, such as leukocytosis, hypercalcemia and cachexia. taken together with the peripheral blood leukocyte (PBL) counts and serum calcium levels during s.c. tumor growth and after surgery, this study suggests that P07 may be a useful experimental model to study the biology of lung cancer and paraneoplastic syndromes.

[Immunoregulation of tumor growth in a murine model]. / Inmunorregulación del crecimiento tumoral en un sistema murino.

Different spleen and tumor cell factors modifying tumoral and metastatic growth were studied. Spleen cell culture supernatants (SCS) from small and large tumor-bearing mice enhanced tumor growth. After tumor surgery, tumor enhancement was only mediated by supernatants from large tumor resected mice. Tumor facilitation and angiogenic response were mediated by the same supernatants; different fractions for these two activities were characterized. T and non-T cells, depending on tumor burden, were responsible for the enhancing activity; but angiogenesis depended only on T cells. While augmentation of metastatic spread was produced by tumor antigens (soluble tumor extracts, tumor-cell supernatants, formolized tumor cells), primary tumor development was not modified by tumor-cell supernatants. Increased incidence of metastases was also mediated by SCS from tumor resected mice which had previously been inoculated with tumor antigens. Immune status of tumor-resected mice was evaluated by delayed-type hypersensitivity reaction. Tumor cell membranes enriched with cholesterol-hemisuccinate were able to increase anti-tumor immune response.

Inmunorregulación del crecimiento tumoral en un sistema murino. / [Immunoregulation of tumor growth in a murine model]

Different spleen and tumor cell factors modifying tumoral and metastatic growth were studied. Spleen cell culture supernatants (SCS) from small and large tumor-bearing mice enhanced tumor growth. After tumor surgery, tumor enhancement was only mediated by supernatants from large tumor resected mice. Tumor facilitation and angiogenic response were mediated by the same supernatants; different fractions for these two activities were characterized. T and non-T cells, depending on tumor burden, were responsible for the enhancing activity; but angiogenesis depended only on T cells. While augmentation of metastatic spread was produced by tumor antigens (soluble tumor extracts, tumor-cell supernatants, formolized tumor cells), primary tumor development was not modified by tumor-cell supernatants. Increased incidence of metastases was also mediated by SCS from tumor resected mice which had previously been inoculated with tumor antigens. Immune status of tumor-resected mice was evaluated by delayed-type hypersensitivity reaction. Tumor cell membranes enriched with cholesterol-hemisuccinate were able to increase anti-tumor immune response.