Modulation of tumor-induced angiogenesis by proteins of extracellular matrix.

The formation of new vessels is a known event in enlarging tumors. Furthermore, the metastatic potential is abrogated or reduced markedly in the absence of neovascularization. Shedding of tumor cells into the circulation is not observed until vascularization has occurred. As a result, the interruption of neovascularization could be a good target for cancer control. This research was an attempt to see if two proteins present in extracellular matrix, collagen and fibronectin (FN), could modify the tumor-induced angiogenesis. The strong angiogenic response induced by S13 tumor cells in the skin of BALB/c mice was blocked by treatment with FN and FN-derived peptides. In contrast, collagen did not modify tumor-induced angiogenesis.

Isolated soluble fractions from spleen cell culture supernatants induce tumor enhancement.

Supernatants of spleen cell culture from small-tumor-bearing mice, large-tumor-bearing mice, and large-tumor resected mice were fractionated by Sephadex G-100. The biological activity on tumor growth of all fractions was tested in vivo. It was found that only one fraction (MW: 220-250 kD) from spleen cell supernatants of small-tumor-bearing mice or large-tumor resected mice enhanced tumor growth. In spleen cell supernatants from large-tumor-bearing mice, two fractions had enhancing activity (MW: 220-250 and 100-10 kD). Thus, the surgical resection of large tumor induced disappearance of enhancing activity from the fraction of lower molecular weight.

[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.

Angiogenic activity by spleen cell supernatants from tumor-bearing and tumor-resected mice.

Supernatants of cultured spleen cells (SCS) from small tumor-bearing mice (STBM) and large tumor-bearing mice (LTBM) are able to enhance tumor growth as well as accelerate tumor takes in vivo when inoculated 24 h before tumor implant. After tumor resection enhancing activity disappears at a rate depending on the size of the resected tumor. Spleen cells from tumor-bearing mice also evoke a complex vascular response, lymphocyte-induced angiogenesis (LIA) elicited via the release of lymphokines from activated T cells. As angiogenic factors promote tumor development we investigated if SCS from tumor-bearing and tumor-resected mice contain factors capable of evoking a LIA response. Angiogenic activity was detected by SCS of small and large tumor-bearing mice as well as in large tumor-resected mice. On the other hand, SCS from small tumor-resected mice are not able to evoke an angiogenic response. Possibly, the large antigenic burden in LTRM stimulate the immune system in a different way than in STRM. We can suggest that the different behavior of spleen cells after small and large tumor removal can be explained by quantitative or qualitative changes in the spleen subpopulations.

Nature of the spleen cell populations capable of releasing tumor enhancing factor.

Supernatants obtained from short-cultured spleen cells (SCS) from BALB/c mice bearing a syngeneic mammary transplanted tumor--S13--showed enhancing activity on tumor growth when inoculated into the foot pad of normal syngeneic mice 24 hr before injection of S13 tumor cells. The present work was designed to characterize the spleen cell population responsible for the releasing of the enhancing factor (EF) as long as the tumor grows (small tumor bearing mice--STBM--and large tumor bearing mice--LTBM). Pretreatment of spleen cells with anti-Thy 1.2 serum + C' and nylon-wool columns were utilized to separate cell populations and to characterize the cellular source of the enhancing activity in the spleens of STBM and LTBM. In this tumor system, evidence is presented for distinct enhancing cell population operating in the spleens of STBM and LTBM. In early stages of tumor development, the EF was found to be associated with T and non-T cells, whereas in advanced stages of tumor growth, this activity was found to be associated with only T cells.

Regulation of tumor growth by soluble spleen factors: effect of tumor resection.

Supernatants of cultured spleen cells (SCS) from small-tumor-bearing mice (STBM) and large-tumor-bearing mice (LTBM) were tested in vivo by their ability to modify tumor development. We found that when inoculated with S13 tumor cells into the foot-pad of syngeneic normal BALB/c mice, SCS enhanced tumor growth as well as accelerated tumor takes. When STBM and LTBM were operated on, the persistence of the enhancing activity by SCS was found to be associated with tumor size at the time of tumor removal. As early as 24 hours after small-tumor resection, enhancing activity disappeared or diminished to undetectable levels. On the other hand, enhancing activity by SCS from large-tumor-resected mice (LTRM) persisted until 15 days after surgery, and then faded. Enhancing activity associated with SCS from S13-tumor-bearing mice (TBM) was also seen when injected with M3 cells, a syngeneic unrelated tumor. Normal SCS did not affect tumor development. It seems that the rate of disappearance of enhancing activity observed in SCS from S13-tumor-resected mice (TRM) is mainly dependent on the size of tumor burden at the time of surgery.

[Modification of the graft versus host response (G.V.H.R.) in maternal lymphoid cells during allogenic gestation evolution (author's transl)]. / Modifications de la réaction greffon-contre-hôte (R.G.C.H.) des cellules lymphoides maternelles au cours de l'évolution de la gestation allogénique.

This study evaluates the maternal immunological response at different stages of gestation in the mouse. This response has been measured by the local G.V.H.R. of lymphocytes from uterine draining lymph nodes and spleens. The results reported here show that the maternal immunological reaction-against paternal antigens carried by the foetus-is lower at the beginning of gestation (on days 6-7) and increases significantly during the last period between 14 and 18 days. In contrast, the temporal G.V.H.R. response of maternal splenocytes is inverted, with lower values from day 14 to day 18.

Immune reactivity of spleen cells in advanced stages of tumor growth.

In a syngeneic tumor model by an indirect migration inhibition technique, using spleen cells from mice bearing large tumors (ATB-SC) no detectable amounts of migration inhibition factor (MIF) was found in response to either tumor cells or tumor extract. Although lymphokine production was suppressed, ATB-SC were able to respond to exogenous MIF and also to transfer a positive delayed foot-pad reaction (DFR) when co-inoculated with both forms of antigen into normal mice. These observations showed that in advanced stages of tumor development, when the ability of spleen cells to produce MIF toward tumor cells or tumor extract is lost, neither their capability to transfer a positive DFR not their responsiveness to MIF-rich culture supernatants were impaired.

Tumor delayed hypersensitivity reactions. "In vivo" functional differences between spleen and peripheral blood lymphocytes.

In a syngeneic BALB/c transplantable tumor model, specific delayed hypersensitvity reaction, detected by foot-pad swelling test appeared specifically suppressed or "eclipsed" in advanced tumor bearing mice. This "eclipsed" response could not be reversed after tumor resection. Unresponsiveness was analyzed by local adoptive transfer of lymphocytes from two different sources. When spleen cells (SC) from advanced tumor bearing and advanced tumor resected mice were locally transferred into normal recipients, a positive cutaneous delayed hypersensitivity (CDH) reaction was observed. While when peripheral blood lymphocytes (PBL) from the same anergic donors were transferred, no CDH reactivity was elicited. Functional differences between SC and PBL populations are suggested to explain these findings.