In situ augmentation of class I major histocompatibility antigen expression on immunogenic variants of a spontaneous murine mammary carcinoma

The relationship between expression of cell surface glycoproteins encoded by the major histocompatibility complex (MHC) and immunogenicity of a recently obtained spontaneous murine mammary adenocarcinoma (designated CBA.SP1) was examined. Immunogenic and nonimmunogenic variant clones were isolated from a subclone of the parent tumor after treatment with the mutagen N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) or the DNA hypomethylating agent and "gene activator," 5-aza-2'-deoxycytidine (5-aza-dCyd). All clones from the untreated tumor population were tumorigenic in normal syngeneic recipients. In contrast, immunogenic variant clones, isolated at high frequencies after drug treatment [ranging from 5% (5-aza-dCyd treated) to greater than 90% (MNNG treated)], were rejected in normal syngeneic mice but grew progressively in T-cell deficient nude mice. Consistent with our previous report (J. Natl. Cancer Inst., 75: 291, 1985), all 5-aza-dCyd induced immunogenic clones expressed elevated levels of class I (particularly Dk) MHC antigens. However some (three out of nine) nonimmunogenic clones also showed enhanced class I MHC expression, implying that not all high MHC expressors were immunogenic. In contrast to 5-aza-dCyd induced variants, only 50% of MNNG induced immunogenic variants showed elevated levels of Dk or Dk and Kk antigens in vitro. Strong augmentation of class I MHC antigens in situ was observed on all immunogenic, but not nonimmunogenic, clones following transplant into syngeneic mice; no increase in MHC expression on variants during progressive growth in athymic nude mice occurred. Although no class II (Ak or Ek) antigens were detected on the parent line or any of the immunogenic variants, a strong infiltration of host I-A bearing cells occurred during immune rejection of SP1 variants. These results are consistent with the hypothesis that induction of class I MHC antigen expression on certain low MHC expressing tumors, although not the sole requirement for immunogenicity, can facilitate immune rejection of the SP1 tumor and, conversely, that the reduced level of MHC observed in certain clinical cancers may significantly affect the immunological aspects of the tumor-host relationship.     

Failure of expression of class I major histocompatibility antigens to alter tumor immunogenicity of a spontaneous murine carcinoma

We have shown previously that clonal immunogenic variants of murine mammary adenocarcinoma 10.1 can be isolated after treatment in vitro with the DNA-hypomethylating agent 5-azacytidine (5-aza). Such immunogenic variants frequently express elevated class I major histocompatibility complex antigens relative to the level of expression in the parent tumor and are rejected in syngeneic mice by a T-cell-dependent process. To ascertain whether elevated immunogenicity is a function of increased class I antigen expression, we isolated high class I antigen expressors from 5-aza-treated 10.1 cells by using the fluorescence-activated cell sorter. Clonal variants displaying any increase in class I antigen expression were more efficient stimulators of allo-class I antigen-specific cytolytic T-cell precursors. However, these variants displayed unaltered tumorigenicity in immunocompetent syngeneic mice. Thus, phenotypic changes other than, or in addition to, elevated class I antigen expression cause the reduced tumorigenicity of immunogenic clones of 10.1 cells isolated after 5-aza treatment.     

Effects of murine tumor class I major histocompatibility complex expression on antitumor activity of tumor-infiltrating lymphocytes

Tumor-infiltrating lymphocytes (TILs) are T cells that can be grown from enzyme-digested murine or human tumors. When adoptively transferred to tumor-bearing hosts concurrent with the administration of recombinant interleukin-2 (rIL-2), TILs can mediate significant regression of tumor. To examine whether expression of class I major histocompatibility complex on tumor cells influenced the generation and antitumor activity of TILs, we used clones of murine B16BL6 melanoma either transfected with or lacking the class I gene Kb to generate TILs at a high dose (1,000 U/mL) or at a low dose (20 U/mL) of human rIL-2. TILs grew from both tumors in high-dose rIL-2, but they grew from the class I-expressing tumor only in low-dose rIL-2. TILs from the class I-deficient tumor did not lyse any target tested in vitro, nor did they demonstrate any therapeutic effect in vivo on established tumors that lacked or expressed class I. In contrast, TILs from the class I-expressing tumor specifically lysed the tumor of origin in vitro and caused it to regress in vivo. Further, these TILs demonstrated activity in vitro against the non-class I-expressing melanoma treated with the combination of murine recombinant interferon gamma and human recombinant tumor necrosis factor alpha; in vivo, when administered with recombinant interferon gamma and recombinant tumor necrosis factor alpha, TILs from the class I-expressing tumor mediated regression of non-class I-expressing pulmonary metastases, presumably by augmenting class I expression.     

Association of expression between N-myc gene and major histocompatibility complex class I gene in surgically resected human neuroblastoma

Amplification of the N-myc gene in neuroblastoma correlates with advanced stage and poor prognosis. Association of the expression between N-myc and major histocompatibility complex (MHC) class I genes in 33 neuroblastomas obtained from Japanese children was investigated. Amplification of the N-myc gene was observed in two of five cases in Stage III, six of 11 cases in Stage IV, and one of five cases in Stage IV-S. In each case, the expression of N-myc gene was significantly increased. The expression was also increased in cases without amplification of the N-myc gene, the origin being from the suprarenal region. Expression of the MHC class I gene was significantly decreased in five of these nine with a high level of N-myc expression with amplification. These results suggest that the down-modulation of the MHC class I expression may be associated with the high level of expression and amplification of N-myc gene in the advanced stage of neuroblastoma.     

Xenogenization of a mouse lung carcinoma (3LL) by transfection with an allogeneic class I major histocompatibility complex gene (H-2Ld)

We investigated the tumorigenicity and immunogenicity of tumor cells transfected with an allogeneic class I major histocompatibility complex gene. A single clone (3LL/3) from a Lewis lung carcinoma in the C57BL/6 strain (H-2b) was cotransfected with a BALB/c genomic clone containing an H-2Ld gene and a bacterial neo gene conferring resistance to G418. Three Ld-positive, three Ld-negative, and two Neor clones were selected by means of a 125I-protein A binding assay using an anti-H-2Ld monoclonal antibody. The antigenic expression of the H-2Ld gene products was only 20-40% on the Ld-positive clones compared with Meth-A tumor cells of BALB/c mice. The 50% lethal tumor dose of these clones in C57BL/6 mice was 5.6 X 10(6) in the Ld-positive clones, but only 1.3 X 10(5) in the 3LL/3 parent clone, 1.2 X 10(5) in the Neor clones, and 2.2 X 10(5) in the Ld-negative clones. The tumorigenicity of the Ld-positive clones was, therefore, reduced to less than 1/40 of that of the parent tumor cells. The decreased tumorigenicity of the Ld-positive clones was abrogated in mice irradiated with 600 rads. After inoculation and spontaneous regression of the viable Ld-positive clone cells, the mice acquired transplantation resistance against the challenge of a parental 3LL/3 tumor. However, the immunogenicity variation between Ld-positive, Ld-negative, Neor, and 3LL/3 parent clones showed no statistical difference. These results indicate that tumor cells transfected with an allogeneic class I H-2 gene can express an H-2 foreign antigen, can regress in syngeneic hosts, and can induce antitumor transplantation resistance against the original tumors, although they are not able to enhance their immunogenicity.     

Frequent down-regulation of major histocompatibility class I antigen expression on individual micrometastatic carcinoma cells

An astoundingly high frequency of micrometastatic cells have been found in bone marrow aspirates of patients with colon carcinomas (G. Schlimok et al., J. Clin. Oncol., 8:831-837, 1990), although these tumors very rarely metastasize to the skeleton. This observation has raised questions about the malignant potential of such cells. In a first attempt to characterize this potential, we have assessed the expression of major histocompatibility complex (MHC) class I antigens on bone marrow micrometastases, inasmuch as down-regulation of these molecules is a potential mechanism to escape from MHC class I-restricted lysis by cytotoxic T-cells. The two groups of cancer patients compared were those with tumors known to rarely (stomach and colon cancer) or frequently (breast cancer) manifest skeleton metastases. Bone marrow aspirates taken from these patients were probed for individual disseminated tumor cells using the immunoalkaline phosphatase technique with monoclonal antibody CK2 to the epithelial differentiation antigen cytokeratin 18 (CK-18), as described previously (G. Schlimok et al., Proc. Natl. Acad. Sci. USA, 84:8672-8676, 1987). Specimens containing CK18-positive cells were colabeled with monoclonal antibody W6/32 directed to a framework (or nonpolymorphic) antigenic determinant of MHC class I heavy chains associated with beta 2-microglobulin. W6/32-positive CK-18-positive cells could be detected in 25 of 54 patients (46.3%) with significantly higher incidences in 26 breast cancer patients (61.9%) as compared to 28 patients with carcinomas of the stomach and colon (27.3 and 29.4%). Independent from the origin of the primary carcinoma, the incidence of W6/32-negative CK18-positive cells was positively correlated to both the differentiation grade of the primary tumor (P less than 0.05) and appeared to be linked to the occurrence of regional lymph node metastases (statistically not significant) determined by conventional histological examination. The present results demonstrate for the first time that down-regulation of MHC expression on individual micrometastatic cells correlates to the differential pattern of metastasis obtained by comparing breast and gastrointestinal carcinomas. This finding together with the suggestive link to clinical risk factors supports the significance of reduced MHC class I expression for the survival of residual metastatic cells which is a major determinant of prognosis for patients with solid tumors.     

Influence of major histocompatibility complex class I and II antigens on survival in colorectal carcinoma

HLA-A,B,C and HLA-D molecules present antigenic peptides to the antigen-specific receptor of autologous T-lymphocytes. T-cell-mediated host-versus-tumor response might therefore depend on the presence of these molecules on tumor cells, although the absence of HLA-A,B,C determinants on a cell has been shown to increase its susceptibility to lysis by natural killer cells. To investigate whether the presence or absence of HLA-A,B,C and/or HLA-DR in colorectal carcinoma influences relapse rate and time of tumor-related death, 152 patients who underwent putatively curative surgical treatment were surveyed for a maximum of 65 months (mean, 48 months). As determined by immunohistochemistry, aberrant reduction or loss of HLA-A,B,C/beta 2-microglobulin molecules was more frequent in tumors of the proximal colon than of the rectosigmoid (P = 0.032) and in mucinous carcinomas than in nonmucinous ones (P = 0.022). An abnormal induction of the HLA-D-associated invariant chain (Ii) was more frequent in Dukes' A and B than in stage C (P = 0.046). Reduction/loss of HLA-A,B,C/beta 2-microglobulin was correlated with the absence of HLA-DR (P = 0.024) and Ii (P = 0.005). In contrast to the prognostic role of tumor stage and grade, the presence versus the absence of HLA-A,B,C/beta 2-microglobulin and HLA-DR/Ii molecules was not correlated with recurrence rate or survival. We conclude that in spite of an increasing amount of experimental data suggesting the contrary, the status of HLA-A,B,C and HLA-DR expression in colorectal carcinoma seems to be irrelevant in vivo, regarding survival and growth of residual tumor cells after putatively curative resection of the initial tumor burden.     

In vivo immunologic selection of class I major histocompatibility complex gene deletion variants from the B16-BL6 melanoma

The mechanism by which tumor allografts escape host immunologic attack was investigated. B16-BL6 cells (the bladder 6 subline of the B16 melanoma) (H-2b) were transfected with a gene (Dd) encoding an allogeneic class I major histocompatibility complex antigen. Clones that expressed Dd antigen were injected into the footpads of nonimmune syngeneic mice, syngeneic immune mice, and nude mice. Under conditions of immunologic selection a clone that contained multiple copies of the transfected gene formed variants that lacked the transfected gene. Primary tumors and pulmonary metastases of immunized mice and pulmonary metastases of nonimmunized mice had lost the Dd gene and, in most cases, all of the associated plasmid. In contrast, in immunodeficient nude mice, primary tumors and pulmonary metastases retained the Dd gene and the associated plasmid. Deletion of genes encoding cell surface antigens may be one of the mechanisms by which allogeneic tumors escape immunologic attack.     

Regulation of the expression of major histocompatibility complex class I genes in human colorectal cancer

Products encoded by the major histocompatibility complex class I genes are down-regulated in many tumors. The under-representation of HLA antigens in human tumors is usually associated with a poor prognosis. In this report, the expression of HLA genes in human colorectal carcinomas was studied using HLA-A and HLA-B locus-specific probes. Over 50% of the colorectal carcinomas studied showed a reduction in the amount of steady-state HLA mRNA. For some carcinomas, non-coordinated regulation of the HLA-A and HLA-B genes was observed. The HLA expression in some, but not all cases, could be enhanced by gamma-interferon. Over 60% of the colorectal carcinomas also expressed high level of the c-myc oncogene mRNA. However, no correlation could be made between the increase of c-myc expression and the down-regulation of the HLA genes.     

Differential expression of class I major histocompatibility complex determinants by lymphoblastic leukemia-lymphoma cell lines.

Two T-cell lines (XR11-4T and XR11-5T), established from radiation-induced, murine lymphoblastic lymphomas, were examined for the expression of class I major histocompatibility complex antigen and tumor induction. These cell lines expressed class I private determinants, H-2.9 and H-2.26, but not the monomorphic determinant defined by monoclonal antibody M1/42. Both cell lines produced tumors in syngeneic and allogeneic hosts. The monomorphic determinant could be demonstrated on both cell lines following growth in allogeneic (BALB/c mice) but not in syngeneic (RFM mice) hosts. The re-expressed determinant present on cells following growth in allogeneic mice was not of host origin. Thus, tumorigenic x irradiation may differentially affect the expression of class I major histocompatibility complex determinants.     

Association in the expression of Kirsten-ras oncogene and the major histocompatibility complex class I antigens in fibrosarcoma tumor cell variants exhibiting different metastatic capabilities

The metastatic properties of the methylcholanthrene-induced T-10 sarcoma tumor variants which originated in C3H x C57Bl/6 F1 mice are correlated with the relative expression of class I major histocompatibility complex antigens. Both the nonmetastatic and the highly metastatic clones were found to lack the H-2K region-controlled H-2Kb and H-2Kk antigens. However, the nonmetastatic clones express only the H-2Db molecule whereas the metastatic clones express both the H-2Db and the H-2Dk molecules. Transfection of the highly metastatic lines with cloned H-2K genes (Kb, Kk) reduced their tumorigenicity and abolished the formation of metastasis in syngeneic mice, while the transfection of the nonmetastatic lines with cloned H-2Dk genes resulted in shifting the cells to the metastatic phenotype. The present study is aimed to investigate the expression of protooncogenes in the T-10 fibrosarcoma lines that exhibit distinct metastatic properties in correlation with the expressed H-2 antigens. The major oncogene which showed differential expression in the T-10 clones is Ki-ras. The amounts of specific Ki-ras messenger RNA and the Ki-ras Mr 21,000 protein are expressed in elevated levels in the H-2Dk-negative nonmetastatic clones in comparison with a low level of expression in the H-2Dk-positive highly metastatic clones. Expression of H-2K antigens following transfection with cloned H-2K genes had no effect on the expressed Ki-ras oncogene in the T-10 clones. However, transfection of the nonmetastatic cells with the cloned H-2Dk gene resulted in shifting of the cells to a highly metastatic phenotype and in reduction of the expressed c-Ki-ras oncogene.     

Influence of major histocompatibility complex class I, class II and TLA genes on tumor rejection.

T lymphocytes recognize antigen associated with MHC class I and/or class II gene products. Recognition of malignant cells is therefore dependent on presentation of tumor associated antigen(s) by MHC molecules. We have studied immunity to tumors that have down-regulated class I expression. These studies demonstrate a requirement for class I antigens, but suggest that additional factors may also be required for tumor-specific immunity. The MHC also encodes TLA class I antigens, whose function is unknown. Our studies suggest that these molecules function is unknown. Our studies suggest that T lymphocytes, specifically in tumor cells that do not express H-2K or H-2D moieties. Other studies are aimed at improving tumor-specific Th cell generation by producing class II+ tumor cells. The success of these experiments indicates that this approach may be a potentially useful immunotherapy.     

Reduced tumorigenicity of murine tumor cells secreting gamma-interferon is due to nonspecific host responses and is unrelated to class I major histocompatibility complex expression

Spontaneous SP1 murine adenocarcinoma cells transfected with the murine gamma-interferon (IFN-gamma) gene expressed IFN-gamma (SP1/IFN-gamma) failed to grow in syngeneic hosts and grew in nude mice. The rejection of SP1/IFN-gamma cells was related to the amount of IFN-gamma produced and appeared to be mediated primarily by nonspecific cellular mechanisms, although some role for T-cells in the afferent arm of this response is possible. SP1 cells are H2-Kk negative but express class I antigens when producing IFN-gamma. However, class I major histocompatibility complex (MHC) expression, while likely necessary, was insufficient in itself to prevent tumor growth since secretion of greater than 64 units/ml IFN-gamma was needed to inhibit tumorigenicity while only 8 units/ml IFN-gamma could induce class I antigens. Similar results were obtained with the murine colon carcinoma CT-26, a tumor that constitutively expresses class I MHC antigens, further supporting the contention that class I MHC expression is not essential for the rejection response induced by IFN-gamma. The failure of SP1/IFN-gamma cells to protect against a challenge with parent SP1 cells argues that factors other than IFN-gamma production or class I MHC expression are needed to induce a protective response against weakly or nonimmunogenic tumor cells.     

Thymus-leukemia antigen (TL) as a major histocompatibility complex (MHC) class Ib molecule and tumor-specific antigen

Mouse thymus-leukemia antigens (TL) belong to the family of major histocompatibility complex (MHC) class Ib antigens and have a unique mode of expression, i.e., in contrast to other MHC class Ib or Ia antigens, they are found restricted to the intestines in all mouse strains, but also in the thymus of certain strains (TL(+) strains). Nevertheless, a proportion of T lymphomas/leukemias in strains that do not express TL in the thymus (TL(-) strains) feature TL as a tumor antigen. TL was originally defined serologically, but subsequently we have succeeded in generating T cell receptor (TCR) and cytotoxic T lymphocytes (CTL) recognizing TL. By use of TL tetramers free from peptides and transfectants expressing various TL/H-2 chimeric molecules, we have been able to show that TL-specific CTL recognize the alpha1/alpha2 domain of TL without any additional antigen molecules. We previously reported that one of TL's functions in the thymus is positive selection of TCR CTL. Recent studies with TL tetramers revealed that they can bind to normal intestinal intraepithelial lymphocytes (iIEL) and thymocytes in a CD8-dependent, but TCR/CD3-independent manner, while their binding to TL-specific CTL is TCR/CD3- and CD8-dependent. The possible significance of these findings in relation to the roles of TL in the intestines is discussed. We have long been interested in TL as a model tumor antigen which shares characteristics with human differentiation tumor antigens, and we have demonstrated that growth of TL(+) lymphoma cells in vivo is suppressed by immunization with TL(+) skin or dendritic cells (DC) from TL transgenic mice. In addition, anti-tumor effects against TL(+) T lymphomas were obtained by adoptive transfer of TL tetramer strongly-positive TL-specific CTLs.     

Correlation of major histocompatibility complex class I related A (MICA) polymorphism with the risk of developing breast cancer

In the present study, we examined the association of different alleles of MICA gene with the risk of breast cancer development in Iranian population. Our data showed a significant relationship between longer alleles, alleles with 9- and 6-GCT repeat of MICA gene, and a higher risk of developing breast cancer according to the age of onset. The data indicated a 6-fold increase for developing breast cancer in patients carrying the allele with 6-GCT repeat after age 50 (OR = 5.8333, 95% CI: 1.2976–26/2236, P = 0.0172). In addition, patients carrying longer alleles in their genotype (6/6, 6/9, and 9/9 genotypes) were found significantly at higher risk of developing breast cancer than control individuals (OR = 5.6, P = 0.0038, 95% CI: 1.6578–18.9166). In contrast, alleles with short GCT repeat of 4 and 5.1 showed to play a role in reducing the risk of breast cancer (OR = 0.79, P = 0.3643 and 95% CI: 0.4743–1.3157). Women with allele 4 were found twofold more protected against breast cancer (OR = 0.4597, 95% CI: 0.2164–0.9765, P = 0.0401). The results suggested that women with genotypes with 9- and 6-GCT repeat alleles of MICA gene could be considered more potent to develop breast cancer especially at higher age.     

Hexadecylphosphocholine selectively upregulates expression of intracellular adhesion molecule-1 and class I major histocompatibility complex antigen in human monocytes

U 937 cells are widely used as a model system to study human monocytes, since they express typical human monocyte markers and properties. Hexadecylphosphocholine (HPC) is the main representative of a class of synthetic phospholipids, the alkylphosphocholines (APCs), and is able to form stable multilamellar vesicles (MLVs = liposomes) to deliver HPC to monocytes/macrophages. Here we report the ability of both micellar and liposomal HPC (L-HPC) to interact with human monocytes and upregulate specific adhesion molecules. Whereas CD14 could neither be induced by HPC nor by L-HPC on U 937 cells, intracellular adhesion molecule-1 and class 1 major histocompatibility complex (MHC-1) antigen were upregulated by both HPC and L-HPC in a dose-dependent manner. These data support and complete previous studies on HPC-induced activation of U 937 cells and provide additional mechanistic information on the initial steps of HPC-mediated recruitment of macrophages and their antitumor activity.