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p53 loss of heterozygosity (LOH) is a frequent event in tumors of somatic and Li-Fraumeni syndrome patients harboring p53 mutation. Here, we focused on resolving a possible crosstalk between the immune-system and p53 LOH. Previously, we reported that p53 heterozygous bone-marrow mesenchymal progenitor cells undergo p53 LOH in-vivo. Surprisingly, the loss of either the wild-type p53 allele or mutant p53 allele was detected with a three-to-one ratio in favor of losing the mutant allele. In this study, we examined whether the immune-system can affect the LOH directionality in bone marrow progenitors. We found that mesenchymal progenitor cells derived from immune-deficient mice exhibited the same preference of losing the mutant p53 allele as immune-competent matched cells, nevertheless, these animals showed a significantly shorter tumor-free survival, indicating the possible involvement of immune surveillance in this model. Surprisingly, spontaneous tumors of p53 heterozygous immune-deficient mice exhibited a significantly higher incidence of p53 LOH compared to that observed in tumors derived of p53 heterozygous immune-competent mice. These findings indicate that the immune-system may affect the p53 LOH prevalence in spontaneous tumors. Thus suggesting that the immune-system may recognize and clear cells that underwent p53 LOH, whereas in immune-compromised mice, those cells will form tumors with shorter latency. In individuals with a competent immune-system, p53 LOH independent pathways may induce malignant transformation which requires a longer tumor latency. Moreover, this data may imply that the current immunotherapy treatment aimed at abrogating the inhibition of cellular immune checkpoints may be beneficial for LFS patients., (© 2016 UICC.)

Preclinical and clinical studies in our laboratory have suggested that prostaglandin (PG) E2 is involved in anorexia and cachexia development, although the role of COX pathways on the pathogenesis of cancer cachexia remains to be clarified. Expressions of PGE (EP1, EP2, EP3alpha,beta,gamma and EP4) and PGI (IP) receptors in the central nervous system (brain cortex, hypothalamus and brain stem), in peripheral (liver, white adipose tissue and skeletal muscle) and tumor tissue from MCG-101-bearing mice with and without indomethacin treatment were investigated by RT-PCR and immunohistochemistry. Expression of EP1 in the liver and EP4 receptor in white adipose tissue were upregulated and responded to indomethacin treatment, while downregulated expression of EP3 in skeletal muscle from tumor-bearing mice was unresponsive to indomethacin treatment despite improved carcass weight. Expression of EP and IP receptors in brain and tumor tissue from tumor-bearing mice were neither related nor responsive to systemic PGE2 levels including increased IL-1beta, IL-6 and TNF-alpha host activities. The expression IP receptor in CNS, peripheral tissue and tumor tissue was unchanged by cachexia development. Our results suggest that transcription of EP receptors in liver, fat and skeletal muscle tissue may be a control level for host metabolic alterations during tumor progression, while overall EP and IP receptor expression in CNS did not indicate an important control level for appetite regulation in MCG 101-bearing mice despite prostanoid related anorexia., (Copyright 2005 Wiley-Liss, Inc.)

The laboratory opossum, Monodelphis domestica, develops hyperplasia and neoplasia of the corneal stroma after repeated exposure to low doses of ultraviolet radiation (UVR) (non-erythemic in skin). We exposed adult animals from genetically diverse families within our colony to determine whether there are any heritable components to the risk of this form of eye cancer. From about 5 months of age, animals were exposed 3 times a week to a dose of about 125 J/m2 of UVB (spectral peak = 302 nm). Thirty-three sibships (151 individuals) completed at least 30 weeks of the protocol and 137 individuals completed 45 weeks. For genetic analysis, each animal was classified at 30 and 45 weeks as affected with corneal sarcoma or not. Heritabilities were estimated for the dichotomous eye-tumor trait which was highly heritable at both time points. This eye-cancer model system is valuable as a source of material for in vitro studies of angiogenesis and neoplastic transformation, for in vivo studies of tumor therapy and prevention, and for further research on the genetic determinants of cancer.

Four murine cellular tumor models expressing various combinations of oncogenes (SV40 large T and v-Ha-ras, SV40 large T and v-src, SV40 large T and neu, adenovirus EIA and v-Ha-ras) induce sarcoma when they are inoculated s.c. into the DBA/2 syngenic mice. The metastatic patterns, distribution and fate of these tumor cells transplanted by two different routes into syngenic DBA/2 mice have been studied. All the tumor cell lines except EIA-ras, induce massive overt artificial metastases principally in the lung after i.v. injection. In s.c. tumor-bearing mice, a few resting cells colonize the lung as micrometastases. When removed from this tissue context and injected s.c. these cells regain their proliferative potential and grow as local tumors which again give rise to occult pulmonary micrometastases.

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.

Conversion of solid sarcomas and carcinomas into ascites tumors depends on the in vivo selection of phenotypically altered tumor cell variants that can grow in the dissociated form. Once selected, they retain this property even after prolonged s.c. growth as solid tumors. From an s.c.-passaged subline of an ascites-converted murine sarcoma (SEWA-AS12), we were able to separate cells adapted to the ascites form of growth from cells that can only grow in the solid form on the basis of their differential adherence to plastic. Both c-myc and pvt-1 were amplified approximately 63- to 77-fold in the nonadherent subline (SEWA-AS12-NA), but only 5- to 8-fold in the adherent subline (SEWA-AS12-ADH). This suggests that c-myc and/or pvt-1 amplification may provide a selective advantage to cells that can grow in the dissociated form.

To find out whether manipulation of H-2 expression on metastatic cells could alter their metastatic properties, we immunoselected in vivo H-2 antigen variants from a metastatic clone of the T10 sarcoma [originating in a (C57BL/6J X C3H.eB)FI mouse] and tested their metastatic capacity. The unselected metastatic cells (IE7) were previously found to express H-2Db and H-2Dk antigens, but they did not express the H-2K antigens of either parental haplotype. Transplantation of IE7 cells into C57BL/6J irradiated mice resulted in loss of H-2Dk expression and a reduction in H-2Db antigen density. Further transplantation of these cells into non-irradiated C57BL/6J mice led to a total loss of H-2 expression. The cells concomitantly lost their metastatic potency. Immunoselection of IE7 cells in C3H.eB irradiated and non-irradiated mice resulted in cells which were H-2Dk-positive but H-2Db-negative. Cells of these selected variants not only retained their metastatic potential, but in fact were far more metastatic than the unselected IE7 cells. Thus, changes in H-2 expression on tumor cells may alter their metastatic potential. In the case of T10 cells, H-2Dk expression seems to be directly involved in their metastatic capacity.

After mutagenesis of mouse mastocytoma P815, it is possible to obtain variant (tum-) clones that are almost always rejected by syngeneic DBA/2 mice. Most tum- clones express new variant-specific antigens that can be detected by cytolytic T cells (CTL). Occasionally, mice injected with tum- variants eventually develop progressive tumors. Cells from these tumors were analyzed for antigen expression with variant-specific and P815-specific CTL clones. Out of 13 tumors examined, 11 were composed of cells that had clearly lost a variant-specific antigenic determinant. These results indicate that tum- variants induce a specific host rejection response which usually results in complete elimination of the variant cells, but that occasional antigen-loss constitutes an important mechanism of escape. The loss of a variant-specific antigenic determinant from one tum- clone that had escaped rejection allowed the detection of a residual variant-specific determinant. This was demonstrated by isolating a new CTL clone that lysed both the original tum- clone and its antigen-loss variant, but not other P815 targets. Thus, some complex transplantation antigens can be separated into independent determinants by using antigen-loss variants.

The genetics of late appearing MSV tumors showing a progressive growth pattern in AKR mice was investigated. The late MSV tumor response in F1 hybrids depended on the genetic background of the non-AKR parent. Within the 4-month observation period following virus injection, (CBA X AKR) F1, (DBA/2 X AKR)F1, and (NIH X AKR)F1 developed progressing MSV tumors, which exhibited latency and growth behavior comparable to that seen in AKR mice, (BALB X AKR)F1, (B6 X AKR)F1, and (B10br x akr)f1 mice did not show any late MSV tumors. In contrast to early regressing M-MSV tumors, whose development is independent of Fv-1 genotype, late MSV tumor progression is largely a function of this gene, since all late tumors which appeared in (B10BR x AKR) x AKR were observed in Fv-1n homozygous mice, H-2k halotype is a further factor in the occurrence of late MSV tumors, at least in (B6 x AKR) x AKR mice. In crosses of AKR with Fv-1 compatible mice, tumor appearance was strongly associated with inheritance of AKR-Mulv, and MSV recovered from late tumors of first back-cross animals appeared to be a new pseudotype with the endogenous AKR-MuLV. It is suggested that the host genetic control in both early and late MSV tumors is exerted mainly on the helper component of the leukemia-sarcoma complex.

The FBR murine osteosarcoma virus complex, isolated from a radiation-induced osteosarcoma of an X/Gf mouse causes the rapid appearance of osteosarcomas in newborn mice and transforms fibroblasts in vitro. The two components of the FBR-viral complex have been isolated separately in tissue culture: FBR-MuLV by end-point dilution and FBR-MuSV by the establishment of mouse [FBR-NP 117 (NIH 3T3)] and rat non-producer cell lines [FBR-NP415 (REF)]. The host range and RNase Tl fingerprint analysis of FBR-MuLV demonstrated a pattern closely related to, but distinguishable from, Akv-MuLV. Transformed cells from both mice and rats contain a rescuable FBR-MuSV genome. These pseudotypes produce foci in tissue culture and induce osteosarcomas in susceptible mouse strains. An FBR-MuSV (FBR-MuLV) cDNA probe detects a 5.2 kb HindIII and a 9.5 kb EcoRI FBR-MuSV-specific fragment in FBR-MuSV-transformed non-producer rat cells. The same fragments hybridized with a fos specific probe, demonstrating that FBR-provirus contains a c-fos-derived onc-gene.

Previous work has shown that the metastatic potential of RSV-transformed fibroblasts is correlated with the ability to form colonies in 0.6% ("hard") agar. Metastatic subclones were selected by this property from the non-metastasizing fibrosarcoma B77-313 line. A marker chromosome was found at high frequency (90% of cells) in all the subclones studied. This marker was detectable in only 0.5% of the parental B77-3T3 cells, demonstrating that metastatic clone precursors pre-existed, as a small minority, in the parental line. The genotypic marker appeared to be steadily associated with the metastatic phenotype since, after prolonged in vitro propagation, the subclones retained both the marker chromosome and the high metastatic potential. Although the marker chromosome was constantly present, chromosomal numerical and structural aberrations were also found in 20% of the long-term-propagated subclone cells, supporting the suggestion that metastatic properties are associated with cytogenetic instability.

An H-2 heterozygous sarcoma, MDAY, originally induced with methylcholanthrene in an (A X DBA/2)F1 ((H-2a X H-2d) hybrid host was selected for growth in the H-2d homoxygous parental DBA/2 strain by serial intraperitoneal transplantation of ascites tumor cells. An apparent variant, designated MDAY-D2, was obtained which showed the expected loss of the private and public H-2Kk haplotype antigens normally associated with the A strain parent and the original MDAY tumor. Comparison of the original and variant lines revealed a wide variety of a cell surface antigen and receptor differences. Both tumors were found to be highly anaplastic and histologically unclasssifiable. Examination of the two tumor lines growing in vivo revealed a remarkable difference in their metastatic growth potential. The original MDAY line showed little propensity to spread to any organ site, with the occasional exception of liver, after subcutaneous inoculation of (A X DBA/2)F1 mice. In striking contrast, there was a rapid and massive spread of MDAY-D2 to liver, spleen, lungs and kidneys within 12-16 days: liver and spleen could be totally replaced by tumor within 2-3 weeks. These characteristics were observed in both (A X DBA/2)F1 and DBA/2 mice. The tendency to metastasize, as well as loss of the H-2Kk haplotype, appeared stable and irreversible. Although the precise origin of MDAY-D2 is not clear, its metastasizing properties are unique, making it a useful and desirable model to study the biology of metastasis.

Old New Zealand Black (NZB) mice frequently develop reticulum-cell sarcoma and clones of aneuploid cells in their spleens. In order to define the relationship between neoplasms and chromosomal abnormalities, the pattern of distribution of aneuploid cells was studied to see if it corresponds to that expected of the malignancy, and chromosomally aberrant or normal spleen cells were transplanted into syngeneic newborn recipients. The results indicate that aneuploid cells arise focally but may disseminate widely in an affected mouse. A strong association was found between spleen-cell aneuploidy in a transplantation donor and both aneuploidy and histological evidence of reticulum-cell sarcoma in young recipients. Chromosomal aberrations in young recipients were always of donor origin. On the basis of these data, it seems likely that aneuploid clones which arise in the spleens of old NZB mice usually are at least potentially neoplastic.

A longitudinal study of 40 New Zealand Black (NZB) mice and 20 BALB/c control animals was performed. A significant association was observed between the presence of acquired spleen-cell aneuploidy at some time during life and development of histological evidence of reticulum-cell neoplasia in individual animals. This finding is compatible with the hypothesis that aneuploid clones which arise in the spleens of aging NZBs are at least potentially neoplastic. However, no relationship between histologically neoplastic reticulum cell proliferation and aneuploidy was apparent in single splenic specimens obtained from NZB mice of various ages. This lack of association indicates that failure to detect chromosomal abnormalities on direct study of cells from a tumor cannot be taken as evidence that the neoplastic cells themselves lack such abnormalities.

The relationship between the Ah locus and the induction of subcutaneous fibrosarcomas by dibenz[a,h]anthracene and dibenz[a,c]anthracene was investigated in C57BL/6J (Ahb/Ahb), (C57BL/6J)(DBA/2J)F1 (Ahb/Ahd) and (Ahd/Ahd) mice. Ahb/Ahb and Ahb/Ahd mice have the high-affinity Ah receptor and therefore the polycyclic hydrocarbon induction of aryl hydrocarbon hydroxylase activity (cytochrome P1-450) proceeds with ease; Ahd/Ahd mice have the poor-affinity Ah receptor and this induction process proceeds more poorly, by a factor of at least 10-fold. Dibenz[a,c]anthracene proved to be a relatively weak carcinogen, producing less than 3% tumor incidence at doses up to 300 micrograms per mouse. In contrast, dibenz[a,h]anthracene caused an almost 50% tumor incidence in Ahb/Ahb and Ahb/Ahd mice, while causing approximately 2% tumor incidence in Ahd/Ahd mice. Both isomers bind avidly to the cytosolic Ah receptor, and both chemicals induce aryl hydrocarbon hydroxylase activity in Ahb/Ahb and Ahd/Ahd animals. Among progeny of the (C57BL/6J) (DBA/2J) F1 X DBA/2J backcross, 63 of 100 Ahb/Ahd mice and none of 75 Ahd/Ahd mice developed tumors. These data demonstrate a strict correlation between susceptibility to dibenz[a,h]anthracene-induced subcutaneous tumors and expression of the Ahb allele, i.e. presence of the high-affinity Ah receptor and therefore readily inducible P1-450.

Presumptive sarcoma cells have been isolated from primary MSV tumors induced in normal, immunosuppressed (ALG) and athymic nude mice. These cells were atypical in appearance, induced tumors in secondary hosts and expressed the viral antigens gp70, p30 and p12. In vitro growth characteristics of the MSV cells were tested in a variety of assays defining cell transformation. None of these indicated that the virus-positive cells were transformed. Sex chromosome marker studies were carried out to determine if secondary tumor arose solely from proliferation of donor cells or through infection of host tissue. Tumors from female irradiated mice induced by injections of tumor cells derived from male mice contained a high proportion of metaphases of non-donor origin, indicating that infection is an important but not the sole mechanism involved in tumor transfer. These data also demonstrated that many of the sarcoma cells are damaged as a result of infection as shown by the presence of chromosome breaks and aneuploid metaphases. Histologic sections of both regressor and progressor tumors showed that the virus-positive cells were scattered as single cells surrounded by inflammatory cells, rather than as masses of dividing virus-positive cells found in the MSV-induced transplanted tumor. Collectively, these data support the contention that the MSV tumor is the manifestation of a response to a highly noxious virus infection rather than a tumor of dividing, transformed malignant cells.

Bone marrow chimeras, athymic nude rats and a congeneic strain were utilized to verify and further examine non-RT-1 linked background genes that influence immune responses of BN and LEW rats to Moloney sarcomas. In transplants that did not involve RT-1 incompatibility, infusion of high-responder bone marrow into a lethally irradiated low-responder recipient, or low-responder bone marrow into a high-responder recipient, would restore a high antibody response to the gp70 antigen of MuLV. Such transplants did not restore a high response to the p30 antigen. Athymic nude rats did not exhibit a significant response to either p30 or gp70 while euthymic littermates exhibited a significant response to both antigens. Growth of Moloney sarcomas as well as antibody and cellular responses to antigens expressed by such tumors were measured in LEW-IN rats which carry the RT-1 of BN and the background of LEW. For each of these parameters, LEW-IN resembled LEW more closely than BN.