苯乙酸钠增强肿瘤细胞表面HLA分子的表达

以分化绣导剂苯乙酸钠处理肿瘤细胞,以ELISA检测肿瘤细胞表面HLA Ⅰ、Ⅱ类分子表达的变化。结果发现MCF-7、MDA-453、MKN-45以及Hela细胞表面HLA Ⅰ类分子表达较低,而MKN-28和3AO细胞表面HLA Ⅰ类分子高表达。MDA-453、MKN-28、MKN-45、Hela以及3AO细胞表面亦表达HLA Ⅱ类分子,而MCF-7细胞表面缺乏HLA Ⅱ类分子。苯乙酸钠能够诱导MCF-7细胞表面表达HLA Ⅱ类分子;增强MCF-7细胞表面HLA Ⅰ类分子,MDA-453、MKN-28、MKN-45、Hela以及3AO细胞表面HLA Ⅰ、Ⅱ类分子的表达。并且肿瘤细胞表面HLA Ⅰ类分子的表达与苯乙酸钠的作用时间和剂量呈正相关。     

重组hDCN对肝癌细胞株HepG2表面HLA分子表达的影响

目的研究peDNA3．1（＋）-核心蛋白聚糖（DCN）重组质粒对体外培养的HepG2细胞株表面HLAⅠ、Ⅱ类分子表达的影响,探讨DCN增强抗肿瘤免疫应答的作用。方法重组质粒pcDNA3．1（＋）-DCN转染HepG2细胞,用流式细胞术（FCM）检测转染前后HepG2细胞表面HLAⅠ、Ⅱ类分子的表达。结果HepG2细胞低表达HLAⅠ、Ⅱ类分子,经转染重组质粒作用后,HLAⅠ、Ⅱ类分子的荧光强度明显增强。结论rhDCN核心蛋白能上调肿瘤细胞表面HLAⅠ、Ⅱ类分子的表达,这一作用可能参与其抗肿瘤效应机制。     

卵巢癌细胞HLA Ⅰ类分子表达异常和TAP,LMP基因表达的关系

目的:肿瘤细胞表达MHCⅠ类分子是激发肿瘤抗原特异性CTL进行肿瘤免疫治疗的关键,肿瘤细胞HLAⅠ类分子表达异常是肿瘤逃脱免疫监视的重要机制.我们探讨了卵巢癌细胞HLAⅠ类分子表达异常的分子基础.方法:本文以West-ern blot、免疫组化和流式细胞术检测卵巢癌细胞HLA Ⅰ类分子的表达,以RT-PCR检测TAP,IMP基因的表达,探讨肿瘤细胞HLA Ⅰ类分子表达异常的分子基础.结果:卵巢癌中HLA Ⅰ类分子表达异常相当普遍(5/8),并涉及抗原加工相关基因TAP,LMP基因表达异常.25℃培养肿瘤细胞可部分诱导Ⅰ类分子的表达;结论:卵巢癌HLA Ⅰ类分子表达异常与其Ⅰ类抗原加工途径异常有关.     

冷冻影响肝癌细胞HLA和B7分子表达的实验研究

目的：探讨冷冻治疗后机体免疫功能提高的机制。方法：应用流式细胞仪检测人肝癌细胞经0℃或－20℃冷冻后，HLA和B7分子表达率和平均荧光强度的变化。结果：0℃组与对照组比较，HLA－Ⅰ分子和B7－2分子的表达率和平均荧光强度均无明显变化；HLA－Ⅱ分子和B7－1分子的表达率增高，平均荧光强度增强。－20℃组与对照组比较，HLA－Ⅰ、HLA-Ⅱ、B7-1和B7－2分子的表达率均增高，平均荧光强度均增强。－20℃组和0℃组比较，HLA－Ⅱ和B7－1分子的表达率和平均荧光强度均无显著性差异；HLA－Ⅰ和B7－2分子表达率均增高，平均荧光强度均增强。结论：0℃和－20℃冷冻可增强人肝癌细胞HLA和B7分子的表达，这可能是冷冻治疗提高机体免疫功能的机制之一。     

乳腺癌细胞表面MHCⅡ类抗原和共刺激分子表达的研究

目的研究乳腺癌细胞表面MHCⅡ类抗原与共刺激分子CD40、CD80(B7-1)和CD86(B7-2)的表达.方法采用流式细胞技术检测5株乳腺癌细胞MCF-7、SK-BR-3、T47D、MDA-MB-435s和ZR-75 -30表面MHCⅡ类抗原与共刺激分子CD40、CD80(B7-1)和CD86(B7-2)的表达,并与正常乳腺细胞HBL-100作比较. 结果 5株乳腺癌细胞MHCⅡ类分子表达均与正常乳腺细胞HBL-100差异有显著性(P<0.05), MCF-7细胞表达水平最低,约为HBL-100的1/5.MDA-MB-435s与ZR-75-30细胞表达水平为HBL-100的2倍,MDA-MB-435s荧光强度也比HBL-100及其他乳腺癌细胞高,但MDA-MB -435s细胞表面CD40分子表达水平最低,约为MCF-7与HBL-100 CD40分子表达水平的10%. MDA-MB-435s细胞的CD80和CD86分子表达水平与HBL-100相当(P>0.05),另4株乳腺癌细胞的CD80和CD86分子表达均比HBL-100低(P<0.05). 结论乳腺癌细胞表面MHCⅡ与共刺激分子表达异常,不同细胞表面分子的表达有所差异.乳腺癌细胞可通过这些分子表达异常而发生免疫逃逸.     

逆转录病毒载体介导的γ-干扰素基因在人肝癌细胞中的表达研究

以逆转录病毒载体(pLXSN)将人源γ-干扰素(huIFN-γ)基因转导入4种不同的人肝癌细胞株,经G418抗性筛选均获得了阳性克隆.PCR和RT-PCR结果均表明IFN-γ基因已在基因组DNA中整合并表达.IFN-γ生物活性检测结果表明,在基因修饰的4种不同个体人肝癌细胞株及同一细胞株的5种不同克隆中,分泌的IFN-γ活性有较大差别.流式细胞仪检测细胞表面HLAⅠ类分子,结果表明基因修饰肿瘤细胞表面HLAⅠ类分子表达有显著提高.同时还首次对HLAⅠ类分子专一位点A2表达进行了分析,结果表明经IFN-γ基因修饰后,A2表达增加与HLAⅠ类分子总体增加相一致,本实验为进行基因工程修饰的肿瘤疫苗研究奠定了基础.     

肿瘤细胞HLAⅠ类分子表达对NK抗性的影响及IFN-γ的调节作用

目的 探讨肿瘤细胞表面HLAⅠ类分子的表达与NK杀伤的关系及IFN－γ的调节作用。方法 用间接免疫荧光法检测7种肿瘤细胞表面HLA－ABC分子的表达;用鼠抗人HLA－ABC单抗封闭靶细胞后,观察NK杀伤的变化;用IFN-γ处理靶细胞后,观察瘤细胞表面HLA分子表达的变化及NK杀伤的变化。结果 不同肿瘤细胞株表达HLA－ABC分子的比例及荧光强度均不相同,除Karpas外,均表现为不同程度的下降。HLA－ABC表达阴性的K562细胞对NK杀伤最敏感,其他细胞的敏感性均有下降。肿瘤细胞表达HLA－ABC分子的表达多有不同程度的下降。用抗HLA单抗封闭相应位 点后,可使NK杀伤明显增强。用IFN－γ500U／ml处理48h后,白血病细胞K562、黑色素瘤细胞M21和高转移肺癌细胞PG表面HLAⅠ类分子表达明显增加,对NK杀伤的敏感性降低;而人T细胞淋巴瘤Karpas、髓样白血病细胞HL60和结直肠癌细胞HT29经处理后,HLAⅠ类分子表达无明显变化,对NK杀伤的敏感性反而明显增强。IFN－γ促进HL60和HT29细胞的凋亡。结论 NK细胞能识别HLA－ABC分子表达下降或缺陷的肿瘤细胞并发挥杀伤作用;INF－γ能恢复部分肿瘤细胞HLA－ABC分子的丢失,并能促进部分肿瘤细胞的凋亡,提高肿瘤对机体抗瘤机制的敏感性。     

转染B7-1基因的人胰腺癌细胞生物学活性的研究

目的探讨B7-1基因导入人胰腺癌SW1990细胞后肿瘤细胞生物学特性的变化.方法采用RT-PCR及FACS检测B7-1基因的表达.MTT法检测病毒转化细胞体外增殖能力.以肿瘤细胞淋巴细胞混合培养检测淋巴细胞的增殖反应.结果转染后的SW1990细胞表达B7-1阳性,野生型SW1990、SW1990/pLXSN细胞与SW1990/B7-1细胞的形态、体外生长特性及MHC Ⅰ类分子表达水平均无差异.SW1990/B7-1细胞增强PBL体外增殖能力及细胞因子IL-2和IFN-γ的分泌.结论表达B7-1分子的胰腺癌细胞免疫原性增加.     

表达CD40L基因的卵巢癌细胞诱导树突状细胞成熟及分泌Th1型细胞因子的作用机制

目的 探讨转染CD40L cDNA的卵巢癌细胞株OVHM对树突状细胞(DC)成熟、分化的影响及诱导其分泌细胞因子的机制.方法 采用脂质体转染法将鼠全长CD40L基因转染人小鼠卵巢癌细胞株OVHM中,用G418筛选出表达CD40L基因的抗药性克隆细胞(CD40L-OVHM).应用免疫磁珠分选并纯化小鼠骨髓DC.将DC与转染和未转染CD40L cDNA的OVHM细胞混合培养,流式细胞术检测DC细胞表面人主要组织相容性复合物Ⅰ类分子(MHC-Ⅰ)、Ⅱ类分子(MHC-Ⅱ)、CD80、CD86和CCR7的表达,逆转录聚合酶链反应(RT-PCR)检测共培养细胞中白细胞介素(IL)-12、IL-23、IL-27、IL-18、γ干扰素(IFN-γ)、Mig基因的表达.结果 DC与CD40L-OVHM细胞混合培养后可形成集落,且上调了DC细胞MHC-Ⅰ、MHC-Ⅱ、CD80、CD86、CCR7的共刺激分子和黏附分子的表达.在DC+CD40L-OVHM组可检测到细胞因子IL-12、IL-23、IL-27、IL-18、IFN-γ、Mig基因的表达,而在DC组、DC+OVHM组、CD40L-OVHM组、OVHM组未检测到这些基因的表达.结论 表达CD40L的卵巢癌细胞促进了DC的成熟,诱导了Th1型细胞因子的分泌,这可能是转染CD40L基因的卵巢癌细胞产生抗肿瘤效应的机制之一.     

NK细胞杀伤人骨髓瘤RPMI8226细胞的活性及其可能的机制

目的:研究同种异体NK细胞对人骨髓瘤RPMI 8226细胞的杀伤活性及其可能的机制。方法:LDH释放法检测NK细胞对RPMI 8226细胞和人白血病K562细胞的杀伤活性,流式细胞术和RT-PCR法分别检测K562和RPMI 8226细胞中NKG2D配体和HLA-Ⅰ类分子的表达;阻断K562和RPMI 8226细胞中NKG2D配体的表达后,检测NK细胞的杀伤活性。结果:NK细胞对RPMI 8226靶细胞的杀伤活性明显低于对K562靶细胞的杀伤(P<0.01)。K562细胞高表达NKG2D配体,不表达HLA-Ⅰ类分子;RPMI 8226细胞低表达NKG2D配体,高表达HLA-Ⅰ类分子,其HLA基因型为A 01,66;B 58,58;Cw 03,06。阻断NKG2D配体后NK细胞杀伤K562细胞的活性明显降低(P<0.01),而杀伤RPMI 8226细胞的活性无明显改变;阻断HLA-Ⅰ类分子,NK细胞杀伤K562细胞的活性无变化,而杀伤RPMI 8226细胞的活性明显提高(P<0.01)。结论:NK细胞杀伤RPMI 8226细胞的活性较低,其机制与RPMI 8226细胞高表达HLA-Ⅰ类分子、低表达NKG2D配体有关。     

转染CD80(B7-1)基因前后人肿瘤细胞系表面标志表达

第十七届国际癌症大会将于1998年8月24～28日在美丽的巴西港口城市里约热内卢举行.此次大会是继1994年印度新德里第十六届国际癌症大会后,肿瘤界的又一次盛会.会议将特邀世界最著名的科学家作10个大会演讲,并分临床及基础两个大专题广泛交流肿瘤研究领域的最新进展.临床专题:脑、头颈、口腔、甲状腺、食管、肺、胃、肠、肝、胰腺、前列腺、卵巢、子宫、皮肤、软组织、骨等各种癌肿,及原发灶不明者、淋巴瘤、白血病等的诊断与治疗(临床试验、近距离放疗、体外放疗、单抗治疗、大     

Prognostic value of HLA class I expression in patients with oral squamous cell carcinoma

Human leukocyte antigen (HLA) class Ⅰ molecules play a central role in anticancer immunity, but their prognostic value in oral squamous cell carcinoma (OSCC) remains unclear. We examined HLA class I expression in 2 distinct tumor compartments, namely, the tumor center and invasive front, and evaluated the association between its expression pattern and histopathological status in 137 cases with OSCC. Human leukocyte antigen class Ⅰ expression was graded semiquantitatively as high, low, and negative. At the invasive front of the tumor, HLA class I expression was high in 72 cases (52.6%), low in 44 cases (32.1%), and negative in 21 cases (15.3%). The HLA class I expression in the tumor center was high in 48 cases (35.0%), low in 58 cases (42.4%), and negative in 31 cases (22.6%). The 5‐year overall survival and disease‐specific survival rates were good in cases with high HLA class I expression at the invasive front; however, there was no significant difference in survival based on HLA class I expression in the tumor center. In addition, high HLA class I expression was correlated with high CD8⁺ T cell density, whereas negative HLA class I expression was correlated with low CD8⁺ T cell density at the invasive front. These results suggest that it is easier for CD8⁺ T cells to recognize presented peptides in the case of high HLA class Ⅰ expression at the tumor invasive front and could be a prognostic factor for OSCC.     

Loss of HLA class I and mismatch repair protein expression in sporadic endometrioid endometrial carcinomas

Tumor cells can escape from cytotoxic T-cell responses by downregulation of human leukocyte antigen (HLA) class I molecules expressed at the cell surface which has been associated with a deficient mismatch repair (MMR) system in colorectal carcinomas. Our study investigated the association between expression of MMR proteins and HLA class I in sporadic endometrioid endometrial carcinomas (EC). In a consecutively selected cohort of 486 EC patients, MMR proteins (MLH1, MSH2 and MSH6) and HLA class I (HLA-A, -B, -C or β(2) m) were investigated by immunohistochemistry. Expression levels of MMR proteins and HLA class I were compared between low-grade and high-grade ECs. HLA class I expression was compared between tumors with loss (negative immunostaining of ≥1 MMR protein) and expression of MMR proteins. Associations between previously determined numbers of intratumoral CD8(+) T-lymphocytes and expression of MMR proteins and HLA class I and the influence on survival was determined. ECs with loss of MMR protein expression (33.5%) more frequently have loss of HLA-B/C (37.3%), compared to ECs with MMR protein expression (25.5%, p = 0.007). Patients with loss of MMR proteins have a worse disease-specific survival compared to patients with expression (p = 0.039). CD8(+) T-lymphocytes have a positive influence on disease-free and disease-specific survival in the total EC cohort but not in patients with loss of MMR protein expression. In conclusion, our results indicate that loss of MMR protein expression is related to selective downregulation of HLA class I which contributes to immune escape in EC with an abnormal MMR system.     

Low surface expression of B7-1 (CD80) is an immunoescape mechanism of colon carcinoma

Artificially enforced expression of CD80 (B7-1) and CD86 (B7-2) on tumor cells renders them more immunogenic by triggering the CD28 receptor on T cells. The enigma is that such B7s interact with much higher affinity with CTLA-4 (CD152), an inhibitory receptor expressed by activated T cells. We show that unmutated CD80 is spontaneously expressed at low levels by mouse colon carcinoma cell lines and other transplantable tumor cell lines of various tissue origins. Silencing of CD80 by interfering RNA led to loss of tumorigenicity of CT26 colon carcinoma in immunocompetent mice, but not in immunodeficient Rag-/- mice. CT26 tumor cells bind CTLA-4Ig, but much more faintly with a similar CD28Ig chimeric protein, thus providing an explanation for the dominant inhibitory effects on tumor immunity displayed by CD80 at that expression level. Interestingly, CD80-negative tumor cell lines such as MC38 colon carcinoma and B16 melanoma express CD80 at dim levels during in vivo growth in syngeneic mice. Therefore, low CD80 surface expression seems to give an advantage to cancer cells against the immune system. Our findings are similar with the inhibitory role described for the dim CD80 expression on immature dendritic cells, providing an explanation for the low levels of CD80 expression described in various human malignancies.     

B7-1 and B7-2 act differentially in the induction of a T cell response: their impact for a HLA-matched and HLA-mismatched anti-tumor immunotherapy

The efficacy of T cell-based immunotherapy is primarily due to efficient cellular activation that requires the engagement of 2 separate signals, i.e., via the T cell receptor complex and via co-stimulatory molecules the prototype of which is CD28. In cellular activation, the CD28 ligands B7-1 (CD80) and B7-2 (CD86) are thought to play nearly identical roles in T cell activation. We monitored the T cell response upon co-culture with HLA Class I-matched and mismatched renal carcinoma cells, respectively, that express different levels of B7-1 and B7-2, respectively. In a HLA Class I-mismatched co-culture, T cell proliferation, IFN-gamma and GM-CSF secretion equally depend on the levels of B7-1 and B7-2 on tumor cells. In contrast, in a HLA Class I-matched situation, B7-2 is more effective in the induction of IFN-gamma and GM-CSF secretion than B7-1, but both B7 molecules induce T cell proliferation equally efficient. B7-2 is more effective than B7-1 in inducing TNF-alpha and IL-10 secretion in both HLA Class I-matched and mismatched situations. The distinct patterns of cytokine induction by B7-1 and B7-2 obviously depend on the HLA Class I compatibility. These conclusions have substantial implications for the development of B7-based vaccines used for immunotherapies.     

MDA-7/IL-24对Burkitt淋巴瘤细胞的诱导分化作用

目的:研究黑色素瘤分化相关基因-7(melanoma differentiation associated gene 7,MDA-7)/IL-2对Burkitt淋巴瘤细胞的促分化作用并探讨其作用机制.方法:构建稳定过表达MDA-7/IL-24的人Burkitt淋巴瘤Raji和Daudi细胞株,MTS法检测稳定转染MDA-7/IL-24对Raji和Daudi细胞活力的影响;Transwell小室实验检测转染MDA-7/IL-24对Raji和Daudi细胞侵袭和迁移能力的影响;流式细胞术检测细胞凋亡水平及免疫表型;Western blotting技术检测转染MDA-7/IL-24对Raji和Daudi细胞表达分化相关蛋白Myb、BLIMP1及BCL-6的影响;建立裸鼠Raji细胞移植瘤模型,检测在体内环境中稳定转染MDA-7/IL-24对Raji细胞生物活性的影响.结果:过表达MDA-7/IL-24的Raji和Daudi细胞其增殖(P.＜0.05)、侵袭(P＜0.01)及迁移(P＜0.01)能力均明显下降,但凋亡细胞无明显增加(P＞0.05),表达CD45及CD138的水平均明显增加(P＜0.01),而表达CD10的水平明显下降(P＜0.01).过表达MDA-7/IL-24的Raji和Daudi细胞表达BLIMP1的水平明显增加(P＜0.01),而表达Myb及BCL-6的水平均明显减低(P＜0.01).MDA-7/IL-24过表达组裸鼠模型Raji细胞移植瘤质量明显低于对照组[(1.23±0.21)vs(1.96±0.24)g,P＜0.01].结论:转染MDA-7/IL-24可能通过诱导分化作用抑制Burkitt淋巴瘤细胞的生物活性.     

HLA-G expression in malignant melanoma

Both, the expression of HLA-G (a non-classical HLA class I molecule) and the loss of classical HLA class I molecules enable tumor cells to evade from immunosurveillance of the host. Whereas HLA-G down-modulates the immune functions of all cells participating in the immune defence mechanisms, defects on HLA class I expression result in the resistance of tumor cells to cytotoxic T lymphocytes attacks. This contribution reviews the HLA-G expression pattern in malignant melanoma lesions, its correlation to the loss of classical HLA class I antigens, and new aspects of HLA-G regulation.     

T cell recognition of HLA‐A2 restricted tumor antigens is impaired by the oncogene HER2

The HER2 oncogene is frequently over‐expressed in human cancers and a promising target for immune therapy. Previous studies have shown that over‐expression of mouse or rat HER2 leads to markedly reduced levels of major histocompatibility complex (MHC) class I and molecules of the antigen processing and presentation machinery (APM), thus resulting in a phenotype promoting tumor escape from the immune system. Our study focuses on analyzing the effect of HER2 on MHC class I antigen presentation and sensitivity to tumor‐antigen specific cytotoxic T lymphocytes (CTLs) in HLA‐A2.1⁺ melanoma cell lines. We demonstrate significant inverse correlations both between the expression of HER2 and total MHC class I surface expression as well as between HER2 and HLA‐A2. A significant reduction of HLA‐A2 levels was found when melanoma and carcinoma cell lines were transfected with a human HER2 gene. A signaling‐competent HER2 molecule was crucial for the observed HLA‐A2 down‐regulation, as transfectants expressing high levels of HER2 mutated in the tyrosine signaling domain did not show altered HLA‐A2 expression. Importantly, the human melanoma cell line EST049 demonstrated reduced HER2 and melanoma antigen‐specific recognition by CTLs upon HER2 transfection. In addition, high expression of HER2 prevented both IFN‐γ mediated HLA‐A2 up‐regulation and improved recognition by HLA‐A2‐restricted CTLs in treated cells. Moreover, key APM molecules were down‐regulated by HER2. These findings implicate that HER2 over‐expressing tumors may be more prone to escape from HLA‐A2 restricted CTLs suggesting that immunotherapy approaches inducing an integrated humoral, cellular and innate immune response would be most effective.