Breast Cancer Cell/Peripheral Blood Lymphocyte MHC Expression And Its Correlation To Clinical Pathology And Cytokine Intervention

Objective Tumor cells generated either in sito or metastasized from elsewhere should always be under the immune surveillance of the body. The immunological relationship between tumor and its host has become the cut-in of tumor biotherapy. MHC plays pivotal role in immune response and the most important step is the recognition of tumor antigen by the effector cells. Despite of its self-tissue origin, oncogenesis always produce specific tumor antigen. Theoretically, cancer developed from successful immune escape. Tumor cells often lack of certain components required for the activation of immune system. Tumor immunity is mainly a T cell dependent cellular immunity. Soluble tumor antigen is taken and processed into short peptides by antigen present cell (APC). The antigenic peptides bind to MHC Class II molecules and coactivate CD₄⁺ T cells. Cytokines secreted from the activated CD₄⁺ T cells will stimulate specific effector function of CD₈⁺ cells. Surface tumor antigen can also be processed within the tumor cells and presented as short peptides to the tumor cell surface, where they bind to MHC Class I molecules and directly activate CD₈⁺ effector cells.In tumor immunity, successful activation of CD₄⁺ T and CD₈⁺ T cells depends on intact expression of MHC Class I/II molecules. Reduced or lack of expression of MHC Class I/II molecules renders CTL recognition of tumor antigen impossible and thereby, makes successful tumor escape. Abnormal expression of MHC molecules hasbeen observed in many tumor cell lines. Reduced or lack of MHC expression was also reported in many human cancers, including beast cancer. However, no study has measured the MHC expression panel in breast cancer cells and analyzed the impact of tumor cell MHC status on host immune function, response to targeted cytokine intervention, MHC targeting gene therapy, tumor specific CTL inducing cancer vaccines, tumor antigen targeting monoclonal antibodies. Furthermore, studies on the MHC expression in Chinese breast cancer patients are extremely rare.c-erbB-2/neu gene rearrangement and CerbB-2 over expression are both poor prognostic index and play important roles in the origination and development of malignancies. The over expression and significance of c-erbB-2/neu in breast cancer patients may offer a potential targets for humoral and cellular immune therapies. c-erbB-2/neu over expression is accompanied by a high expression of other proteins, as well as an accumulation of large amount of MHC Class I peptide complex. A MHC Class I - limited and Her-2 peptide specific CTLs potentially has more efficient anti-tumor effects on her-2 positive cancer cells. In vivo and ex vivo experiments revealed that Herceptin-CerbB-2 complex can be internalized and processed into MHC Class I binding peptides, which bind to MHC Class I molecules and induce enhancive CerbB-2 specific CTL effects. Therefore, the expression of MHC could affect the anti-tumor of Herceptin. Evaluation of the CerbB-2 and MHC correlation might predict the clinical effectiveness of Herceptin.CerbB-2 targeted T cell mediated tumor vaccine is an important biotherapeutic strategy for breast cancer. However, CerbB-2 over expressed cell lines express significantly smaller amount of MHC Class I molecules. This observation could explain the escape mechanism of breast cancer with certain genotype. Further analysis of CerbB-2 and MHC correlation might help with designing of T cell based immune therapy.Animal experiment shown that INF- Y could up regulate the expression of MHC molecules, indicating a potential impact of certain cytokines on MHC related humoral and cellular immune therapies. The present study is designed to measure the MHC panel expression on breast cancercells and peripheral blood lymphocytes (PBL), to analysis their correlation to clinical pathologic findings, and to evaluate the effectiveness of INF- y intervention on lymphocyte MHC expression.Material and Methods Malignant and nonmalignant tissues from 36 breast cancer patients, and 30 benign breast disease patients were obtained through biopsy or mammectomy. The expression of MHC class I molecules (ABC and A2) and Class II molecules (DP/DQ/DR) were measured by FACS using a panel of FITC conjugated MoAbs. The expression of ER, PR and CerbB-2 in breast cancer tissues from 36 patients was immunochemically stained by using mouse-anti-human MoAbs. Inter-group expression variation was analyzed by using SPSS 11 software. Correlation between MHC expression and clinical pathologic findings (including ER, PR, CerbB-2) was also analyzed.MHC panel expression on peripheral lymphocytes from 20 breast cancer patients and 20 normal controls were measured by FACS using a panel of FITC conjugated MoAbs specific for MHC Class I molecules ABC, A2, and MHC Class II molecules DP, DQ, DR, respectively. Inter-group variation was analyzed by using SPSS 11 software .Peripheral lymphocyte MHC expression before and after short-term INF- y intervention (1 million units/day, subcutaneous injection, for 4 weeks) were compared by paired-T test.Results1. Tissue MHC panel expression in breast cancer patients and in benign breast diseases.The breast cancer and benign breast disease tissue MHC expression was significantly lower than normal breast tissue (P < 0.05). The breast cancer tissue MHC Class I - ABC expression was similar to the benign breast disease tissue (P > 0.05). The benign breast disease tissue MHC Class I - A2 expression was higher than the breast cancer tissue (P < 0.05). The benign breast disease tissue MHC Class II -DP/DQ/DR expression was significantly higher than the breast cancer tissue (P < 0.05).2. Pathologic relevance of breast cancer tissue MHC expressionThe breast cancer tissue MHC Class II - DP/DQ/DR expression was higher in ER positive patients than in ER negative patients (P < 0.05). The breast cancer tissue MHC Class I - ABC, A2, MHC Class II - DP/DQ/DR expression was not relevant to patient age, tumor size and PR expression. Tissue MHC Class I - ABC expression in patients with metastasized lymph nodes was significantly lower than patients without lymph nodes involvement (P < 0.05). Patients with ^ 3 metastasized lymph nodes shown even lower tissue MHC Class I - ABC expression (P < 0.01). No difference was observed in tissue MHC Class I - A2 and MHC Class II - DP/DQ/DR expression between patients with and without lymph node metastasis.The tissue expression of MHC Class I - ABC was higher in CerbB-2 negative patients than in CerbB-2 positive patients (PO.05). The tissue expression of MHC Class I - ABC in 2 to 3 plus CerbB-2 positive patients was even lower (PO.01), indicating a negative correlation between MHC Class I - ABC and CerbB-2 expression. However, the tissue expression of MHC Class I -A2 and MHC Class II -DP/DQ/DR was similar in both CerbB-2 positive and CerbB-2 negative patients (P>0.05).3. PBL MHC panel expression in breast cancer patientsPBL MHC Class I - ABC, A2, MHC Class II -DP/DQ/DR expression was significantly lower in breast cancer than in normal controls (PO.01).4. Impact of short term INF- r intervention on PBL MHC expression in breast cancer patientsPBL MHC Class I - ABC and MHC Class II -DP/DQ/DR expression was slightly increased after short term INF- r intervention, although the difference was not significant (P>0.05). Nevertheless, PBL MHC Class I - A2 expression was significantly elevated after short term INF- r intervention (PO.01).Conclusion1. Reduced MHC Class I/II expression contributes to the molecular mechanism under immune escape in breast cancer.2. Benign breast diseases, as pre-cancers, shown similar MHC Class I expressiondefect to breast cancer. This observation is novel and warrants further study.3. Patients with metastasized lymph nodes and over-expression of c-erbB-2/neu showed even lower MHC expression. MHC expression could be predicative for the clinical response of Herceptin.4. Short term INF- r intervention in breast cancer patients might up-regulate the PBL MHC expression and thereby improve their in vivo anti-cancer immunity.This study evaluated tissue and PBL MHC panel expression defects in breast cancer and benign breast diseases. MHC expression could be a novel negative indicator for the clinical effectiveness of Herceptin in CerbB-2 positive patients. The reduced MHC status in breast cancer might be corrected partly by cytokine intervention. These findings lay fundamental basis for the development of novel biotherapeutic strategies for breast cancer.