Cooperative interaction between c-myc and bcl-2 proto-oncogenes.

The bcl-2 proto-oncogene is activated by translocation in a variety of B-lymphoid tumours and synergizes with the c-myc oncogene in tumour progression. The mechanism of synergy is unclear but bcl-2 expression inhibits apoptosis, a property presumably pertinent to its proto-oncogenic mode of action. We have shown that the c-myc gene is a potent inducer of apoptosis, in addition to its established role in mitogenesis. Here we show that expression of the bcl-2 protein, Bcl-2, specifically abrogates c-myc-induced apoptosis without affecting the c-myc mitogenic function. This provides a novel mechanism for oncogene cooperation, of potential importance both in carcinogenesis and in the evolution of drug resistance in tumours.     

光动力疗法诱导的免疫原性细胞死亡的研究进展

光动力疗法（PDT）已被证明可以诱导免疫原性细胞死亡（ICD）.但是由于PDT本身的局限性以及肿瘤部位的免疫原性差和免疫抑制环境的原因,单独的PDT在癌症免疫治疗中难以获得强大而持久的适应性抗肿瘤功效,往往需要采用不同的策略来提高肿瘤的免疫应答效果.因此,文章简述了光动力学机理、ICD原理,以及对PDT诱导的ICD的各种不同策略进行了总结和讨论,策略包括增加氧气（O₂）和靶向性提高PDT效果,PDT联合光热疗法（PTT）和化疗等治疗方式,PDT结合免疫检查点以及免疫佐剂抑制来提高ICD效应,以此为研究人员提供更多的癌症免疫治疗方面的参考.     

Novel primitive lymphoid tumours induced in transgenic mice by cooperation between myc and bcl-2

The putative oncogene bcl-2 is juxtaposed to the immunoglobulin heavy chain (Igh) locus by the t(14;18) chromosomal translocation typical of human follicular B-cell lymphomas. The bcl-2 gene product is not altered by the translocation, but its expression is deregulated, presumably by the Igh enhancer E mu. Constitutive bcl-2 expression seems to augment cell survival, as infection with a bcl-2 retrovirus enables certain growth factor-dependent mouse cell lines to maintain viability when deprived of factor. Furthermore, high levels of the bcl-2 product can protect human B and T lymphoblasts under stress and thereby confer a growth advantage. Mice expressing a bcl-2 transgene controlled by the Igh enhancer accumulate small non-cycling B cells which survive unusually well in vitro but do not show a propensity for spontaneous tumorigenesis. In contrast, an analogous myc transgene, designed to mimic the myc-Igh translocation product typical of Burkitt's lymphoma and rodent plasmacytoma, promotes B lymphoid cell proliferation and predisposes mice to malignancy in pre-B and B lymphoid cells. Previous experiments have suggested that bcl-2 can cooperate with deregulated myc to improve in vitro growth of pre-B and B cells. Here we describe a marked synergy between bcl-2 and myc in doubly transgenic mice. E mu-bcl-2/myc mice show hyperproliferation of pre-B and B cells and develop tumours much faster than E mu-myc mice. Suprisingly, the tumours derive from a cell with the hallmarks of a primitive haemopoietic cell, perhaps a lymphoid-committed stem cell.     

聚乙烯亚胺-整合素配体复合物介导bcl-2反义核酸对结肠癌细胞的作用

目的:观察聚乙烯亚胺(PEI) -整合素蛋白的配体(Arg -Gly -Asp ,RGD)介导的bcl - 2反义核酸(antisenseoligodeoxynucleotide ,ASODN)对结肠癌细胞caco - 2的作用效果。方法:将阳离子复合物jetPEI-RGD与bcl- 2反义核酸混合形成ASODN -PEI-RGD三聚体复合物,转染caco - 2细胞。用台盼蓝拒染法计数活细胞,观察ASODN -PEI-RGD对caco - 2细胞的生长抑制作用,用流式细胞仪检测细胞的亚二倍体百分率,Heochst332 5 8染色观察细胞凋亡。结果:与ASODN对照组和jetPEI-RGD对照组相比,ASODN -PEI -RGD能够明显抑制caco - 2细胞增殖和诱导细胞凋亡(P<0 0 5 ) ,呈剂量和时间-效应关系。ASODN -PEI-RGD作用4 8h ,荧光染色可见大量的caco - 2细胞核固缩、核碎裂。结论:jetPEI-RGD介导的bcl- 2反义核酸能抑制caco - 2细胞增殖和诱导细胞凋亡。     

Bcl-2 is an inner mitochondrial membrane protein that blocks programmed cell death

The t(14; 18) chromosomal translocation of human follicular B-cell lymphoma juxtaposes the bcl-2 gene with the immunoglobulin heavy chain locus. The bcl-2 immunoglobulin fusion gene is markedly deregulated resulting in inappropriately elevated levels of bcl-2 RNA and protein. Transgenic mice bearing a bcl-2 immunoglobulin minigene demonstrate a polyclonal expansion of resting yet responsive IgM-IgD B cells which display prolonged cell survival but no increase in cell cycling. Moreover, deregulated bcl-2 extends the survival of certain haematopoietic cell lines following growth-factor deprivation. By using immunolocalization studies we now demonstrate that Bcl-2 is an integral inner mitochondrial membrane protein of relative molecular mass 25,000 (25k). Overexpression of Bcl-2 blocks the apoptotic death of a pro-B-lymphocyte cell line. Thus, Bcl-2 is unique among proto-oncogenes, being localized to mitochondria and interfering with programmed cell death independent of promoting cell division.     

Abrogation by c-myc of G1 phase arrest induced by RB protein but not by p53.

Inactivating mutations of the retinoblastoma gene (RB) are found in a wide variety of tumour cells. Replacement of wild-type RB can suppress the tumorigenicity of some of these cells, suggesting that the RB protein (Rb) may negatively regulate cell growth. As activation of c-myc expression promotes cell proliferation and blocks differentiation, it may positively regulate cell growth. The c-myc protein is localized in the nucleus and can physically associate with RB protein in vitro, hence c-myc may functionally antagonize RB function. Microinjection of Rb in G1 phase reversibly arrests cell-cycle progression. Here we co-inject RB protein with c-myc, EJ-ras, c-fos or c-jun protein. Co-injection of c-myc, but not EJ-ras, c-fos or c-jun, inhibits the ability of Rb to arrest the cell cycle. The c-myc does not inhibit the activity of another tumour supressor, p53 (ref. 12). Thus, c-myc and RB specifically antagonize one another in the cell.     

Expression of bcl-2 gene increases in apoptosis of vascular endothelial cells induced by rattlesnake venom

Apoptosis of vascular endothelial cells (VEC) has been induced by deprivation of survival factors (aFGF and serum) and by rattlesnake venom. The expression of bcl-2 gene has been examined by Northern blotting in the two apoptosis inducing systems. Our results show that the expression of bcl-2 has not been detected in normal culture cells and in apoptotic cells induced by deprivation of survival factors. But in apoptotic cells induced by rattlesnake venom (10 g/mL), the expression of bcl-2 increases, and its mRNA exhibits two bands. The data first suggest that increasing expression and splitting of bcl-2 mRNA may play an important role in apoptosis of VEC induced by rattlesnake venom, and this finding is helpful to understanding the role of bcl-2 in regulation of apoptosis.     

Sortilin is essential for proNGF-induced neuronal cell death

Sortilin (approximately 95 kDa) is a member of the recently discovered family of Vps10p-domain receptors, and is expressed in a variety of tissues, notably brain, spinal cord and muscle. It acts as a receptor for neurotensin, but predominates in regions of the nervous system that neither synthesize nor respond to this neuropeptide, suggesting that sortilin has additional roles. Sortilin is expressed during embryogenesis in areas where nerve growth factor (NGF) and its precursor, proNGF, have well-characterized effects. These neurotrophins can be released by neuronal tissues, and they regulate neuronal development through cell survival and cell death signalling. NGF regulates cell survival and cell death via binding to two different receptors, TrkA and p75NTR (ref. 10). In contrast, proNGF selectively induces apoptosis through p75NTR but not TrkA. However, not all p75NTR-expressing cells respond to proNGF, suggesting that additional membrane proteins are required for the induction of cell death. Here we report that proNGF creates a signalling complex by simultaneously binding to p75NTR and sortilin. Thus sortilin acts as a co-receptor and molecular switch governing the p75NTR-mediated pro-apoptotic signal induced by proNGF.     

Inducible nitric oxide synthase expression is related to angiogenesis,bcl—2 and cell proliferation in hepatocellular carcinoma

In this study,we examined the expression of inducible nitric oxide synthase(iNOS) and vascular endothelial growth factor(VEGF) by immunohistochemical staining in 76 tissue sections collected from bepa-tocellular carcinoma(HCC) patients undergoing hepatectomy.Microvascular density (MVD) was determined by counting endothelial cells immunostained using anti-CD34 antibody.We performed DNA-flow cytometric analyses to elucidate the impact of iNOS and VEGF expression on the cell cycle of HCC.Most of the HCC cells that invaded stroma were markedly immunostained by iNOS antibody.The iNOS stain intensity of the liv-er tissue close to the tumor edge was stronger than that of HCC tissue,and the strongest was the hepatocytes colser to the tumor tissue.However,iNOS expression in 10 normal hepatic samples was undetectable.VEGF positive expression ratio was 84.8% in iNOS positive expression cases,and the ratio was 35.3% in negative cases.There was significant correlation(P=0.000) between iNOS and VEGF expression.Moreover,iNOS expression was significantly associated with bcl-2 and MVD,but without p53 expression.DNA-flow cytometric analyses showed that combined expression of iNOS and VEGF had significant impact on the cell cycle in HCC.PI(Proliferating Index) and SPF(S-phase fraction)in the combined positive expression of iNOS and VEGF group was significantly higher than that in the combined negative group.The present findings suggested that iNOS expression was significantly associated with angiogenesis,bcl-2 and cell proliferation of HCC.     

Dampening of death pathways by schnurri-2 is essential for T-cell development

Generation of a diverse and self-tolerant T-cell repertoire requires appropriate interpretation of T-cell antigen receptor (TCR) signals by CD4(+?) CD8(+) double-positive thymocytes. Thymocyte cell fate is dictated by the nature of TCR-major-histocompatibility-complex (MHC)-peptide interactions, with signals of higher strength leading to death (negative selection) and signals of intermediate strength leading to differentiation (positive selection). Molecules that regulate T-cell development by modulating TCR signal strength have been described but components that specifically define the boundaries between positive and negative selection remain unknown. Here we show in mice that repression of TCR-induced death pathways is critical for proper interpretation of positive selecting signals in vivo, and identify schnurri-2 (Shn2; also known as Hivep2) as a crucial death dampener. Our results indicate that Shn2(-/-) double-positive thymocytes inappropriately undergo negative selection in response to positive selecting signals, thus leading to disrupted T-cell development. Shn2(-/-) double-positive thymocytes are more sensitive to TCR-induced death in vitro and die in response to positive selection interactions in vivo. However, Shn2-deficient thymocytes can be positively selected when TCR-induced death is genetically ablated. Shn2 levels increase after TCR stimulation, indicating that integration of multiple TCR-MHC-peptide interactions may fine-tune the death threshold. Mechanistically, Shn2 functions downstream of TCR proximal signalling compenents to dampen Bax activation and the mitochondrial death pathway. Our findings uncover a critical regulator of T-cell development that controls the balance between death and differentiation.     

Genomic analysis of increased host immune and cell death responses induced by 1918 influenza virus

The influenza pandemic of 1918-19 was responsible for about 50 million deaths worldwide. Modern histopathological analysis of autopsy samples from human influenza cases from 1918 revealed significant damage to the lungs with acute, focal bronchitis and alveolitis associated with massive pulmonary oedema, haemorrhage and rapid destruction of the respiratory epithelium. The contribution of the host immune response leading to this severe pathology remains largely unknown. Here we show, in a comprehensive analysis of the global host response induced by the 1918 influenza virus, that mice infected with the reconstructed 1918 influenza virus displayed an increased and accelerated activation of host immune response genes associated with severe pulmonary pathology. We found that mice infected with a virus containing all eight genes from the pandemic virus showed marked activation of pro-inflammatory and cell-death pathways by 24 h after infection that remained unabated until death on day 5. This was in contrast with smaller host immune responses as measured at the genomic level, accompanied by less severe disease pathology and delays in death in mice infected with influenza viruses containing only subsets of 1918 genes. The results indicate a cooperative interaction between the 1918 influenza genes and show that study of the virulence of the 1918 influenza virus requires the use of the fully reconstructed virus. With recent concerns about the introduction of highly pathogenic avian influenza viruses into humans and their potential to cause a worldwide pandemic with disastrous health and economic consequences, a comprehensive understanding of the global host response to the 1918 virus is crucial. Moreover, understanding the contribution of host immune responses to virulent influenza virus infections is an important starting point for the identification of prognostic indicators and the development of novel antiviral therapies.     

Apoptotic signal pathways and regulatory mechanisms of cancer cells induced by IL-24

The melanoma differentiation-associated gene-7(mda-7),IL-24,has the specific functions that induce cancer cell apoptosis without doing harm to normal cells. We systematically review the apoptotic signal pathways and their regulatory mechanisms induced by Ad.IL-24 and IL-24 in diverse cancer cells. IL-24 can participate in varied signal transduction pathways,including JAK,p38 MAPK,Wnt/β-catenin,JNK,ER stress and mitochondria-associated signal pathways. And we review five proteins interacting with IL-24,including Bip/GRP78,S1 R,PKR,Beclin1 and soluble clusterin,which are relative to the tumor-specific effect of IL-24. It is speculated that ER stress,G-protein pathways and MAPK signal pathways may be the primary upstream effectors which activate the sequential downstream mediators resulting in apoptosis induced by IL-24 in tumor cells. Experimental results also show that IL-24 sensitizes cancer cells and indirectly promotes apoptosis rather than functions as a direct apoptosis inducer itself.     

棉铃虫单粒包埋型核型多角体病毒诱发草地贪夜蛾细胞株Sf的程序性死亡

棉铃虫单粒包埋型核型多角体病毒（ＨａＳＮＰＶ）能够诱发草地贪夜蛾Ｓｆ细胞株发生早期死亡现象．依据死亡过程的细胞形态变化，ＤＮＡ降解的梯状电泳特征以及对不同抑制剂敏感性的差异，可以初步断定该死亡现象为程序性死亡．早期死亡伴随着病毒ＤＮＡ复制与子代病毒生成的中止．同时发现野生型ＡＣＭＮＰＶ的共感染能够有效地抑制早期死亡的发生，并对抑制作用的可能性机制进行了探讨．     

Wild-type p53 induces apoptosis of myeloid leukaemic cells that is inhibited by interleukin-6.

Wild-type p53 protein has many properties consistent with its being the product of a tumour suppressor gene. Although the normal roles of tumour suppressor genes are still largely unknown, it seems that they could be involved in promoting cell differentiation as well as in mediating growth arrest by growth-inhibitory cytokines. Hence, the abrogation of wild-type p53 expression, which is a common feature of many tumours, could eliminate these activities. We have now tested this notion by restoring the expression of p53 in a murine myeloid leukaemic cell line that normally lacks p53. The use of a temperature-sensitive p53 mutant allowed us to analyse cells in which the introduced p53 had either wild-type or mutant properties. Although there seemed to be no effect on differentiation, the introduction of wild-type p53 resulted in rapid loss of cell viability in a way characteristic of apoptosis (programmed cell death). The effect of wild-type p53 was counteracted by interleukin-6. Thus products of tumour suppressor genes could be involved in restricting precursor cell populations by mediating apoptosis.