The Study Of Nonfamilial Primary Breast Cancer Molecular Mechanism And The Correlation Between Different Clinical Pathology Factors

ObjectiveBreast cancer is one of the diseases most greatly damaging to women's health. It is of crucial significance to explore the nonfamilial primary breast cancer molecular mechanism, tumor escaping immunological surveillance and self-immunotolerance for breast cancer research. There are many researches about BRCA1and BRCA2 gene mutation on familial breast cancer, while a few on nonfamilial breast cancer, 90% of all breast cancers. Many factors involve in breast cancer advancing, not only gene mutation. Immunological suppression and immunological surveillance escaped are also of concernful importance.RhoBTB2 (rho-related BTB domain-containing 2 ,RhoBTB2) was named in 2002. It is presumed expression absence or inactivity in most breast cancers[1]. Moreover, it is one of few genes related to nonfamilial primary breast cancer and may be the main tumor suppresser gene candidate for breast cancer. Researches about RhoBTB2 were barely processed abroad, and limited to breast cancer cell lines in vitro, while never in China.Fas(Apo-l, CD95) belongs to TNF super family. It distributes on surfaces of T cell, B cell, monocyte and other immunocytes, and plays an important role in immune modulation. There were a few of researches on relations between Fas and breast cancer, but inconsistent, and never refered to clinical pathology factors.CTLA-4 (cytotoxic T lymphocyte associated antigen-4) belongs to immunoglobulin super family. It distributes on surfaces of activated CD4+ T cells, CD8+ T cells, and activated B cell. It is involved in immunoreactive diseases, transplantation exclusion, tumor process, anti-infection, and anti-hypersensitivity, which induced by T cells. Researches about CTLA-4 trans signal converter mostly focused on immunoreactive diseases, little on tumor.Our research was a branch of Shandong Natural Fund Project Y2004C17, and will be the pioneer of RhoBTB2 research. Our purpose was to explore the nonfamilial primary breast cancer molecular mechanism, tumor escaping immunological surveillance and self-immunotolerance for breast cancer, and will indicate new target in breast cancer gene therapy.Materials and MethodsChose 60 operable primary breast cancer patients and 30 benign breast disease patients diagnosed in Shandong Breast Disease Center from Jan. 1999 to May. 2004. Cancer tissues were resected within primary tumor, and normal control tissues were resected aside from benign breast disease tissues. Once resected, stored in -196℃. We distilled total RNA from tissues with TRI Zol according to instructions, then did RT-PCR and electrophoresis on 1.5% agarose gel. Strips were scanned and analysed by Gel Dos1000 Gel Image Analyzer. Takenβ-actin of each sample as reference, we computed relative expressions with the gray degree ratios of aimed gene andβ-actin.β-actin1 was taken as reference for Rhobtb2 and CTLA-4, andβ-actin2 for Fas. SPSS 13.0 software was used for statistics.Results1. Rhobtb2 gene Rhobtb2 gene expressions were significantly lower in breast carcinoma tissues than control. The relative quantitative means of Rhobtb2 gene in breast carcinoma and control tissues were 0.625±0.160 vs 0.843±0.218, P<0.01. Mean Rhobtb2 expression in invasive ductal carcinoma tissues was lower than invasive lobular carcinoma tissues, 0.597±0.157 vs 0.717±0.145, P<0.05. There were no obvious differences when ages, axillary lymph node metastasis, clinical stages, ER, PR, HER2 and survival time varied.2. Fas Fas expressions were significantly higher in breast carcinoma tissues than control. The relative quantitative means of Fas in breast carcinoma and control tissues were 0.699±0.285 vs 0.502±0.178, P<0.01. Mean Fas expression in axillary lymph node metastasis positive patients was 0.782±0.313, while in axillary lymph node metastasis negative patients was 0.557±0.146, P<0.01. There were no obvious differences when ages, pathology types, clinical stages, ER, PR, HER2 and survival time varied.3. CTLA-4 CTLA-4 expressions were significantly higher in breast carcinoma tissues than control. The relative quantitative mean ranks of CTLA-4 in breast carcinoma and control tissues were 60.03 vs 16.43, P<0.01. Mean CTLA-4 expression in stageⅡandⅢcarcinoma tissues were 0.978±0.33, 1.134±0.24, P<0.05. There were no differences when ages, pathology types, axillary lymph node metastasis, ER, PR, HER2 and survival time varied.There were no notable correlations of Rhobtb2, Fas and CTLA-4 gene expression in breast carcinoma group. In control group, there were correlations between Fas and CTLA-4, CTLA-4 and RhoBTB2, the correlation coefficient were -0.591 and 0.417. There was no notable correlations between Fas and RhoBTB2.Conclusions1. Tumor suppresser gene RhoBTB2 can play a role in breast cancer early diagnosis as a new special breast cancer tumor marker, and in biologic treatment as a new target.2. The results indicated that not all the tumor cells escapes immunological surveillance by the absence or decrease of Fas expressed on the cells surface. It will be a new challenge to the traditional theory. The detection of Fas is valuable in investigating breast cancer molecular mechanism, early diagnosis and prognosis assessed.3. Immunotolerance may be a reason of tumor cells escaping immunological surveillance in breast cancer. Application of CTLA-4 antibody and tumor vaccine lies a considerable foreground in tumor protection and treatment. Moreover, CTLA-4 can also be a tool of early diagnosis and prognosis assessed tumor marker.4.The correlation research of RhoBTB2, Fas and CTLA-4 will illumine the road of exploring for breast cancer molecular mechanism, immunological suppression and immunological surveillance escaping.