Biomedical subjects

R Falcioni

Publications and source records attributed to R Falcioni.

25 records · Page 2Linked to original sources

PubMed1988

MHC antigens expressed on 3LL metastatic variants: correlation with the expression of a TSP-180 protein.

In attempts to correlate metastatic potential with specific properties of tumor cells, homogeneous subpopulations, which are endowed with low or high metastatic potential, have been selected from Lewis lung carcinoma (3LL). In particular, since cell surface constituents are possibly involved in the metastatic process, changes in antigen expression have been correlated with the metastatic potential of 3LL variants. In this view, we quantitated the expression of MHC (Db,Kb) antigens and of a tumor specific protein (TSP) identified by the monoclonal antibody (MoAb) 135-13C on some "in vitro" and "in vivo" variants of 3LL. The MoAb 135-13C was found to recognize a TSP-180 protein that appears on the cell surface of several murine carcinomas, but is not detected on normal cells in culture. Studies of the MHC expression on these variants, by the use of the indirect immunofluorescent staining or the direct binding of the MoAb to H-2Db (28-14-8) and the MoAb to H-2Kb (28-13-3), demonstrate that "in vivo" and "in vitro" 3LL variants which, are endowed with a higher metastatic potential, express on the cell surface a higher amount of the Db antigen. By contrast, all the 3LL lines have few cells recognized by the MoAb to H-2Kb and express low amounts of this antigen on the cell surface. The direct binding to different tumor lines and the analysis of the immunoprecipitates from the cell lysates by the use of the MoAb 135-13C demonstrate that the TSP-180 protein is highly expressed on 3LL cells which possess high capacity to metastasize to the lung. The variations induced in 3LL metastatic phenotype by the injection of the variant lines in allogeneic mice (Balb/c, C3HeB:H-2d,H-2k, respectively) or after treatment with the specific MoAb 135-13C have, also, been studied. An attempt was made to correlate the changes in 3LL metastatic phenotype with the expression of the TSP-180 protein and of the MHC antigens. We conclude that a high expression on the cell surface of the Db antigen and of the TSP-180 protein, is associated with a high malignant phenotype of 3LL tumor cells.

Animals↗

PubMed1986

Expression of tumor antigen correlated with metastatic potential of Lewis lung carcinoma and B16 melanoma clones in mice.

Expression of a tumor-associated antigen, recognized by a monoclonal antibody (MoAb 135-13C) to lung carcinoma cells, has been studied in cloned Lewis lung carcinoma (3LL) and in B16 melanoma (F1 and F10) tumor lines endowed with different metastatic potentials. MoAb 135-13C recognizes a protein complex (tumor-specific Mr 180,000 protein) that appears on the cell surface of several murine lung carcinomas but is not detected on normal cells in culture. Standard metastatic variants of B16 melanoma (F1 and F10) and two variant sublines of 3LL (M1087 and BM21548) together with the parental line of 3LL have been used for these experiments. The two cloned variant lines derived from 3LL have been shown to retain high (M1087) and low (BM21548) metastatic phenotypes during in vivo passaging. We found that all three cell lines of 3LL bind monoclonal antibody specifically, but one cell variant with higher metastatic potential shows a higher capacity to bind MoAb 135-13C than did the other variant. Similarly we found that B16 F10 cells bind higher amounts of MoAb 135-13C than did B16 F1 cells. In addition the analysis of the amounts of MoAb 135-13C bound to the cell surface of several other in vitro and in vivo tumor lines with different metastatic capacity demonstrates that all tumor lines which express high ability to colonize to the lung also express, on the cell surface, higher amounts of tumor-specific Mr 180,000 protein. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis autoradiograms of immunoprecipitates from cell lysates of 3LL and B16 tumor lines demonstrate that MoAb 135-13C specifically precipitated three proteins banding at molecular weights of 204,000, 134,000, and 116,000. We conclude that MoAb 135-13C recognizes a surface protein complex which is present in higher amounts in 3LL and B16 cells which possess higher capacity to metastasize to the lung.

Animals↗

PubMed1984

Analysis of translation products synthesized in isolated rat hepatocytes treated with diethylnitrosamine.

Isolated rat hepatocytes were labeled with 35S-methionine in the presence of 25 mM diethylnitrosamine (DENA). The intrinsically labeled proteins were analyzed by one- and two-dimensional gel electrophoresis and the fluorographic patterns were compared with those obtained from untreated hepatocytes. The results of short term experiments (2 h) show that, in the presence of 25 mM DENA, protein synthesis is inhibited by 50%. This reduction encompasses all protein species without selective inhibition of certain proteins.

Animals↗

PubMed1984

Heat-shock proteins produced by two human melanoma cell lines: absence of correlation with thermosensitivity.

Two human melanoma cell lines, extremely different in their thermal sensitivity, were pulse-labelled with (35S)-methionine after 60 min of exposure at 42 degrees C. For both cell lines, fractionation of the intrinsically labelled proteins by polyacrylamide gel electrophoresis (PAGE) showed increased labelling of a polypeptide band of Mr 72,000, along with a slight reduction of overall protein synthesis. By two-dimensional electrophoresis, the Mr 72,000 band resolved into multiple pattern components of the same size but differing in isoelectric points. The absence of qualitative and quantitative differences between the two melanoma cell lines indicates that the different thermal sensitivities are unrelated to their ability to express the heat-shock proteins.

Cell Line↗

PubMed1984

Modulation of heat shock protein synthesis in two human melanoma cell lines.

Two human melanoma cell lines, largely different from one another in their intrinsic thermosensitivity, were exposed to supranormal temperatures and labeled with 35S-methionine. The protein patterns resolved by SDS-polyacrylamide gel electrophoresis showed in both cell lines an increased synthesis of a unique set of heat shock proteins (HSP) of 72 Kdalton (KD). Already evident after 15 min at 42 degrees C, the relative rate of synthesis of these HSP increased progressively for up to 3 h of continuous heat treatment. The cells exposed for 1 h at 42 degrees C and then returned to 37 degrees C maintained a high relative rate of HSP synthesis for more than 6 h. The rate of decay of the neosynthesized HSP did not differ from that of the overall cell proteins. Since in both cell lines all the parameters concerning HSP induction were identical, no correlation can be established between their intrinsic sensitivity towards the conditioning treatment and the capacity to respond to heat treatment with an increased synthesis of these proteins.

Cell Line↗

PubMedDate not supplied

Stimulation of tumor cell growth in vitro by a monoclonal antibody to a tumor specific protein (TSP-180) present on the cell surface of 3LL cells.

Proliferation capacity and MHC class I antigen expression of two Lewis lung carcinoma (3LL) metastatic variants (C87, BC215) grown under defined experimental conditions (serum-free defined medium or 10 per cent serum) have been studied following exposure to MoAb 135-13C which recognizes on these cells a tumor surface protein of 180,000 daltons (TSP-180). The results of this study indicate that the high metastatic clone (C87) binds higher amounts of MoAb to TSP-180 and Db antigens than does the low metastatic one (BC215), while both clones express very low amounts of Kb antigens. 3LL clones grown in 10 per cent serum or adapted in serum-free, defined medium show the same metastatic phenotype and MHC class I antigen expression, but when grown in defined medium exhibit increased capacity to bind MoAb 135-13C. However, the relative binding rate of 3LL clones grown in 10 per cent serum or in defined medium is unchanged: the high metastatic clone always showing higher capacity to bind MoAb to TSP-180. Furthermore, comparison of EGF binding sites on the cell surface of 3LL clones, grown in different culture conditions, demonstrates that the C87 clone binds higher amounts of labelled EGF and that this amount increases in serum-free defined medium, exactly as reported for TSP-180. In addition, competition experiments demonstrated that MoAb 135-13C does not compete for EGF binding sites on 3LL cell surface. Studies on cell proliferation following exposure to MoAb 135-13C, revealed that the low metastatic clone (BC215) is more actively stimulated than the high metastatic one. Moreover, similar data were obtained after exposure of 3LL clones to physiological amounts of different growth factors (i.e. EGF, MSA, insulin). Analysis of MHC class I antigen expression following exposure to MoAb 135-13C indicated that MoAb 135-13C induces on the cell surface of the C87 clone a transient low modulation of Db antigens. These results suggest that 3LL cells endowed with lower metastatic potential are more dependent on the microenvironmental conditions than the high metastasizing ones, and that MoAb 135-13C binding to 3LL cell surface stimulates proliferation as reported for several known growth factors.

Animals↗

PubMedDate not supplied

Metastatic phenotype: growth factor dependence and integrin expression.

Homogeneous subpopulations, which are endowed with low or high metastatic potential, were selected from Lewis lung carcinoma (3LL) in an attempt to correlate metastatic phenotype with specific properties of tumor cells. Since the growth of malignant cells at secondary sites could depend on their ability to respond to microenvironments, the growth factor dependence of 3LL variants has been studied. The ability of variant lines to grow in monolayer and in soft agar cultures, either in the presence or absence of different growth factors or serum, was analyzed and correlated with their metastatic potential. The reported results demonstrate that tumor cells expressing higher metastatic potential also exhibit higher capacity to grow and proliferate in all the culture conditions tested, independently of the addition of exogenous growth factors or serum. Moreover, since highly metastasizing cells express a significant amount of TGF-beta 1 mRNA, a pattern of autocrine growth is postulated for 3LL metastatic cells. One relevant aspect of the phenotype of transformed cells is their reduced adhesion to solid substrates; this phenomenon is thought to reflect the invasive and metastatic potential of tumor cells. Since the adhesion of the cells to substrata is mediated by molecules of the extracellular matrix, the expression of extracellular matrix receptors (integrins) was studied on 3LL metastatic variants. In particular, through immunochemical and biochemical studies we investigated the expression of the laminin receptor(alpha 6/beta 1) and of a novel receptor (integrin: alpha 6/beta 4), of unknown function. The receptors were quantitated on the cell surface of 3LL variants by the use of specific monoclonal antibodies which recognize, respectively, different epitopes of alpha 6, beta 4 or beta 1 subunits. Results demonstrate that the novel integrin alpha 6/beta 4, is specifically expressed in highly metastasizing 3LL cells, whereas the laminin receptor alpha 6/beta 1 is expressed in all 3LL variants. In conclusion, data presented demonstrate that 3LL cells endowed with higher metastatic potential are more independent of the microenvironmental conditions in that they possess a higher autocrine capacity than the lower metastasizing ones, and could acquire higher capacity to invade through the expression on their cell surface of specific receptors for cell adhesion (the novel integrin, defined as alpha 6/beta 4).

Animals↗