Biomedical subjects

J J Gaforio

Publications and source records attributed to J J Gaforio.

25 records · Page 2Linked to original sources

PubMed1993

Generation and control of metastasis in experimental tumor systems; inhibition of experimental metastases by a tilorone analogue.

The role of the chemical compound RMI 10,874DA (3,6-bis[2-(dimethylamino)-ethoxyl]-9H-xanthene-9-one dihydrochloride) in the abrogation of the metastatic spread of tumor cells was studied. Pre-treatment of BALB/c mice with the RMI 10,874DA compound (referred to below as tilorone analogue) completely eliminated lung colonization of an H-2-negative (GR9.B9) MCA-induced fibrosarcoma clone in an experimental metastasis assay. Other murine tumors, including H-2-positive and H-2-negative chemically induced fibrosarcoma clones and B16 melanoma, were also sensitive to the treatment; orally administered tilorone analogue given one day before the i.v. injection of tumor cells markedly inhibited lung colonization. The effect was not due to direct toxicity of tilorone analogue on tumor cells, but instead it was dependent on NK cells; this was suggested by the finding that anti-asialo GM, treatment of mice abrogated the effect of tilorone analogue. Kinetic studies of splenic NK activity in tilorone-treated mice showed a rapid boosting of NK-cell activity, the greatest stimulation occurring the day before removal of splenocytes for 51Cr-release assay against YAC-I target cells. These kinetics correlated with the inhibition of in vivo lung colonization after tilorone analogue treatment. Inhibition of experimental tumor metastasis was dose-dependent and was observed when animals were treated the day before or the day after tumor-cell injection. Furthermore, repeated treatment of mice with this tilorone analogue significantly reduced lung colonization.

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PubMed1992

Effect of MHC class-I transfection on local tumor growth and metastasis in an H-2-negative clone derived from a chemically induced fibrosarcoma.

GR9 is a chemically induced fibrosarcoma composed of clones with different H-2 class-I expression. These clones differ with respect to local growth and spontaneous metastasis. The B9 clone (H-2 negative) is highly tumorigenic (local growth) but of low metastatic potential (spontaneous metastasis assay). We have analyzed the effect that transfection of H-2Dd and H-2Kd genes on this clone have upon local growth, lung colonization after i.v. injection and ability to form spontaneous metastases. The results showed that the effect on local growth of transfection of the Kd-gene was stronger than that of the Dd gene. In addition, B9 co-transfected with H-2Kd and Dd genes showed the highest immunogenic properties in syngeneic BALB/c mice. Interestingly, the pSV2-neo transfected clone gave almost the same result as that obtained with Dd transfection. Lung colonization after i.v. injection of the different clones (experimental metastasis), paralleled the results obtained for local growth: the number of lung nodules followed the cadence KdDd less than Kd less than Dd less than pSV2. Survival of mice was always inversely correlated with local growth, e.g., all mice injected with 5 x 10(5) B9 H-2KdDd transfected cells survived. In contrast, no mice injected with the B9 control did. These differences were abrogated in irradiated and nude BALB/c mice. Finally, all transfected clones remained non-metastatic in a spontaneous metastasis assay, behaving as the control, non-transfected B9 cells.

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PubMed1991

Differential mRNA levels of c-myc, c-fos and MHC class I in several clones of a murine fibrosarcoma.

We have evaluated the relationship between MHC class-I, c-myc and c-fos proto-oncogene expression in several clones of a methylcholanthrene-induced fibrosarcoma (GR9) which originated in a BALB/c mouse. These clones represent a heterogeneous population and differ markedly with regard to H-2 class-I cell-surface expression, local tumor growth, NK sensitivity and metastatic potential. In the present study we show that cell-surface expression of MHC class-I antigens correlates inversely with levels of c-myc mRNA transcripts. On the other hand, mRNA levels of c-fos are correlated directly with the amount of mRNA of MHC class I. Treatment of the B9 clone with gamma interferon increased mRNA transcription and surface expression of H-2 class-I antigens, while c-myc transcription was simultaneously down-regulated. In contrast, c-fos mRNA levels remained unaltered.

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PubMed1991

Heterogeneity of MHC-class-I antigens in clones of methylcholanthrene-induced tumors. Implications for local growth and metastasis.

We analyzed the H-2 class-I expression of different clones obtained from 4 different methylcholanthrene-induced tumors in BALB/c (H-2d) mice. The results clearly indicated high intra-tumor heterogeneity in all 4 fibrosarcomas with regard to H-2 K, D and L expression. Clones were found to be H-2-negative, H-2-positive, or to present intermediate expression. Southern blot analysis of class-I genes showed RFLPs equal to those obtained from normal BALB/c DNA, ruling out rearrangements or gross deletions in the class-I genes of different tumors. However, Northern blot studies showed a straightforward relationship between class-I mRNA levels and H-2 expression. In vivo experiments demonstrated an inverse relationship between local growth and spontaneous metastasis, e.g., H-2-positive class-I clones produced high numbers of lung colonies but very poor local growth, and vice-versa. These results paralleled the NK sensitivity or resistance of the different clones. Cross-protection experiments showed that only clones coming from the same tumor were able to protect against challenge with clones of the same neoplasia but not with clones from different chemically induced fibrosarcomas, indicating that a clone of a given tumor probably contained the same TATA. Finally, we compared the H-2, K, D and L expression and class-I mRNA levels of various metastatic colonies. Interestingly, another degree of heterogeneity was found: an H-2-negative clone (GR9.B9) gave rise to H-2-negative (B9MP6) and H-2-positive (B9MP2) metastatic colonies.

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PubMed1990

A weakly tumorigenic phenotype with high MHC class-I expression is associated with high metastatic potential after surgical removal of the primary murine fibrosarcoma.

We have examined the metastatic capacity of different clones of a chemically induced fibrosarcoma GR9. These clones have previously been characterized for their H-2 class-I and class-II phenotype, NK sensitivity and local tumor growth. Our present data show that clones which express low amounts of H-2 class-I antigens are poorly metastatic in a post-surgical spontaneous metastasis assay, while those expressing high levels of class-I antigens possess a high metastatic capacity. These results correlate inversely with local growth patterns of the clones. High metastatic capacity was associated with resistance to NK cells. In an experimental metastasis assay, based on intravenous administration of in vitro carried GR9 clones to syngeneic BALB/c mice, an opposite result to the post-surgical assay was obtained. Gamma-IFN treatment of B9 clones (H-2-deficient) enhanced H-2 class-I expression and diminished experimentally induced metastases. Metastatic colonies, from the spontaneous metastasis assay, obtained from different organs, showed changes in the ratio H-2K/H-2D. There was a tendency for down-regulation of the expression of H-2K molecules in H-2-positive clones and for up-regulation of H-2D expression in H-2-negative clones.

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PubMedDate not supplied

c-K-ras overexpression is characteristic for metastases derived from a methylcholanthrene-induced fibrosarcoma.

We investigated the relationship between the activation of the c-myc and c-K-ras proto-oncogenes and the acquisition of metastatic potential in a methylcholanthrene-induced BALB/c fibrosarcoma. The murine fibrosarcoma GR9 was originally induced in BALB/c mice following exposure to the carcinogenic chemical 3-methylcholanthrene. To induce spontaneous metastasis, we used two tumor cell clones (B9 and G2) known to differ in their metastatic potential, local tumor growth, H-2 class I expression and sensitivity to natural killer (NK) cells. The metastatic nodes were obtained from the lung, liver and kidney. The results showed: (1) amplification of the c-myc proto-oncogene in original tumor clones as well as in all metastatic nodes; (2) mRNA overexpression without amplification of the K-ras proto-oncogene in the metastatic cells, regardless of their anatomical location; (3) no c-K-ras point mutations at codons 12 and 61, and (4) in general, a statistically significantly reduced in vitro sensitivity of metastatic tumor cells to NK cells as compared with the tumor clones used to induce them (p<0.05). These results therefore suggest that overexpressed c-K-ras mRNA is important during tumor progression, perhaps rendering metastatic tumor cells more resistant to lysis by NK cells.

Animals↗

PubMedDate not supplied

The biological consequences of altered MHC class I expression in tumours.

The identification of different mechanisms by which tumours escape from the immune system has helped to evaluate the clinical relevance of a variety of phenotypic changes that occur during tumour development. Among them, changes in HLA class I expression play a leading role in the tumour-host environment since HLA class I molecules interact with T lymphocytes for antigen presentation and with NK cells for inhibition/activation of these immune effector cells. Our laboratory has proposed a classification of the altered HLA class I phenotypes frequently found in human tumours, into five major groups. This review focuses on the tumour phenotypes found in primary and metastatic lesions, the molecular mechanisms that give rise to each phenotype and the clinical implications of these findings.

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