5-氟尿嘧啶通过促进miR-22表达抑制肝癌细胞增殖

目的研究5-氟尿嘧啶(5-FU)对miR-22在肝癌细胞中表达的影响及其抑制肝癌细胞增殖的分子机制。方法用Real-time PCR法检测肝细胞癌组织及细胞系中miR-22的表达;用Real-Time PCR法检测经不同浓度5-FU处理的肝癌细胞HepG2和Huh7中miR-22及其初始转录产物pri-miR-22的表达;用miR-22类似物及5-FU处理肝癌细胞HepG2和Huh7,并用Western blot法检测miR-22靶基因HDAC4的表达;设计拯救实验(rescue assay)研究5-FU、miR-22与肝癌细胞增殖的关系。结果 miR-22在肝细胞癌组织及细胞系中表达下调;5-FU可以诱导肝癌细胞系HepG2、Huh7内源性miR-22、pri-miR-22表达水平明显上调(P0.01);miR-22过表达及5-FU处理可以抑制HepG2、Huh7,HDAC4蛋白表达水平(P0.01)。结论 5-FU通过调控miR-22介导的HDAC4信号通路发挥抑制肝癌细胞增殖的作用。     

Marek's disease virus VP22: subcellular localization and characterization of carboxyl terminal deletion Mutations

Marek's disease virus (MDV) is an alphaherpesvirus that causes T cell lymphoma and severe immunosuppression in chickens. The MDV UL49 gene, which encodes the tegument viral protein 22 (VP22), has been expressed as a green fluorescent protein (GFP) fusion protein in chicken embryonic fibroblasts to examine its subcellular localization. As with both human herpesvirus 1 and bovine herpesvirus 1VP22-GFP fusion proteins, the MDV VP22-GFP product binds to microtubules and heterochromatin. In addition, the MDV protein also binds to the centrosomes. During mitosis, VP22-GFP binds to sister chromatids, but dissociates from the centrosomes and the microtubules of the mitotic spindle. A series of VP22 carboxy terminal truncation mutants were constructed to define regions responsible for these binding properties. These mutants identified separable domains or motifs responsible for binding microtubules and heterochromatin.     

An adenoid squamous carcinoma-forming cell line established from an oral keratinizing squamous cell carcinoma expressing carcinoembryonic antigen.

A neoplastic epithelial cell line, TYS, was isolated from a well-differentiated squamous cell carcinoma expressing carcinoembryonic antigen (CEA) that arose in human oral mucosa. Expressions of CEA and amylase as well as ample tonofilaments were detected in cultured TYS cells. Transplantation of the cells into athymic nude mice resulted in production of adenoid squamous cell carcinoma containing CEA and amylase. Cultivation of TYS cells in the presence of sodium butyrate resulted in suppression of cell growth and production of secretory granules with amylase in the cytoplasm of the cells. When the sodium butyrate-treated cells were transplanted into nude mice, a small mass developed transiently at the inoculation site and then disappeared. This mass was histopathologically interpreted as acinic cell carcinoma with squamoid lesion. These findings suggest that we have established a human adenoid squamous carcinoma cell line presumably derived from a minor salivary gland present in oral mucosa.     

Cell cycle effects of IL-10 on malignant B-1 cells

IL-10 is overexpressed in human chronic lymphocytic leukemia (CLL), and is an autocrine growth factor involved in the development of malignant B1 clones in NZB mice, a murine model for CLL. Antisense IL-10 oligonucleotide treatment induces apoptosis and cell cycle disruption in these cells both in vitro and in vivo. In addition, NZB IL-10 knock-out mice fail to develop the B-1 clones. Dampening of IL-10 protein production via antisense IL-10 oligonucleotide treatment is correlated with decreased p27/Kip1 protein expression which results in increased cyclin D2, cyclin E and cyclin A associated kinase activity. The action of the antisense oligonucleotides is through alterations in cell cycle regulation, resulting in accelerated cell cycle progression, a G2/M block which culminates in apoptosis induction in the malignant cells. This implies that the role of IL-10 as an autocrine growth factor in malignant B-1 cells lies in its ability to inhibit apoptosis induction through the maintenance of sustainable cell cycle progression in malignant cells.     

Involvement of apoptotic cell death in autoimmune diseases

A low rate of as well as a high rate of apoptotic cell death is involved in the development of various human autoimmune diseases. In rheumatoid arthritis (RA), impaired apoptosis of rheumatoid synovial cells appears to induce hyperplasia of the synovial tissues, whereas the acceleration of apoptotic cell death of osteoblasts may contribute to periarticular bone loss in patients with RA. Humoral factors including cytokines and growth factors present in the rheumatoid synovial tissues modulate the expression of apoptosis-related molecules in the cells, which inhibits or stimulates the apoptotic process of synovial cells and osteoblasts. In addition, investigations of animal arthritis models suggest that an enforced induction of apoptotic cell death of synovial cells ameliorates synovial tissue hyperplasia. The increase of salivary gland cell apoptosis and the resistance of apoptotic cell death in salivary infiltrating mononuclear cells have been observed in patients with Sj?gren's syndrome (SS). Immunohistochemical studies indicate that X chromosome linked inhibitor of apoptosis protein in salivary gland cells as well as Bcl-2/Bcl-xL in salivary infiltrating mononuclear cells may be critical anti-apoptogenic molecules in each cell type. Human T-lymphotropic virus type I (HTL V-I) is one of the pathogenic organisms for RA and SS, and we demonstrated that HTL V-I tax stimulates NF-kappa B nuclear translocation, inhibiting apoptotic cell death of human host cells, which may accelerate the autoimmune process. The association between the apoptosis of thyrocytes and the process of autoimmune thyroid diseases has also been examined, and our data suggest that Fas-mediated apoptosis of human thyrocytes is modulated by thyroid-stimulating antibodies, thyroid stimulation blocking antibodies, and cytokines. These data indicate that the correction of apoptotic cell death in each cell type will become a new therapeutic strategy for treatment of human autoimmune diseases.     

Endoplasmic reticulum stress causes autophagy and apoptosis leading to cellular redistribution of the autoantigens Ro/Sjögren's syndrome‐related antigen A (SSA) and La/SSB in salivary gland epithelial cells

The aim of this study was to examine the levels of endoplasmic reticulum (ER) stress in minor salivary glands, to investigate the interplay between ER stress-induced autophagy and apoptosis in human salivary gland (HSG) cells and to test the effect of ER stress-induced apoptosis on the cellular redistribution of the two major Sjögren’s syndrome (SS) autoantigens Ro/Sjögren’s syndrome-related antigen A (SSA) and La/Sjögren’s syndrome-related antigen B (SSB). Minor salivary gland biopsies from SS patients and sicca controls were examined by immunohistochemistry for the expression of 78 kDa glucose-regulated protein/binding immunoglobulin protein (GRP78/BiP) as an indicator of unfolded protein response (UPR). HSG cells were treated with thapsigargin (TG) and cell viability, autophagy and apoptosis were assessed. Immunoblot was applied to detect the conversion of LC3I to LC3II and the protein levels of GRP78/BiP and X-box binding protein-1 (XBP-1). Apoptosis was evaluated by a single-stranded DNA enzyme-linked immunosorbent assay (ELISA). Ro/SSA and La/SSB localization was visualized using immunofluorescence. GRP78/BiP was expressed by acinar and ductal epithelial cells in salivary glands of patients and sicca controls. TG treatment induced autophagy, as indicated by enhanced protein expression of LC3II. The protein levels of UPR marker XBP-1 were increased after TG treatment, while GRP78/BiP levels were decreased. TG treatment resulted in induction of HSG apoptosis. Ro/SSA and La/SSB autoantigens were localized predominantly to the cytoplasm in resting cells, while they were redistributed to cell membrane and blebs in the apoptotic cells. In conclusion, ER stress is activated in minor salivary gland epithelial cells from SS patients and controls. ER stress-induced apoptosis in HSG cells leads to cell surface and apoptotic blebs relocalization of Ro/SSA and La/SSB autoantigens.     

Pluripotential reprogramming of the somatic genome in hybrid cells occurs with the first cell cycle

The fusion of pluripotent embryonic cells with somatic cells results in reprogramming of the somatic cell genome. Oct4-green fluorescent protein (GFP) transgenes that do not contain the proximal enhancer (PE) region are widely used to visualize reprogramming of the somatic to the pluripotent cell state. The temporal onset of Oct4-GFP activation has been found to occur 40-48 hours postfusion. We asked whether activation of the transgene actually reflects activation of the endogenous Oct4 gene. In the current study, we show that activation of an Oct4-GFP transgene that contains the PE region occurs within 22 hours of fusion. In addition, demethylation of the Oct4-GFP transgene and that of the endogenous Oct4 and Nanog genes was found to occur within 24 hours of fusion. As this timing corresponds with the timing of cell cycle completion in embryonic stem cells and fusion hybrids (approximately 22 hours), we postulate that pluripotential reprogramming of the somatic cell genome begins during the first cell cycle after the fusion of a somatic cell with a pluripotent cell and has been completed by day 2 postfusion.     

生长抑制因子1基因核定位序列-绿荧光蛋白融合表达载体的构建及表达

目的构建p33^ING1b核定位序列（nuclear locating sequence，NLS）-绿荧光蛋白融合表达载体，将其转染到人胚肺纤维母细胞系MRC-5，建立稳定表达该融合蛋白的细胞模型。方法应用逆转录PCR获得p33^ING1b的NLS序列，然后将NLS序列插入绿荧光蛋白融合表达载体pEGFP-C1的多克隆位点，构建pEGFP-C1-NLS-绿荧光蛋白融合表达载体，再用此载体转染MRC-5细胞系，观察活细胞绿荧光蛋白的亚细胞定位。结果成功构建了pEGFP-C1-NLS-绿荧光蛋白融合表达载体，由该载体表达的绿荧光蛋白-NLS肽段融合蛋白产生的绿色荧光信号全部定位于胞核部位，而空载体转染的细胞表达的绿色荧光蛋白，绿色荧光信号定位于细胞浆中。结论在活细胞内，生理情况下p33^ING1b完全定位于细胞核，并且在其亚细胞定位的转运过程中，NLS肽段起着决定性作用。     

Induction of insolubility by herpes simplex virus VP22 precludes intercellular trafficking of N-terminal Apoptin-VP22 fusion proteins

The herpes simplex virus protein VP22 has the intriguing ability to deliver proteins from an expressing cell to neighboring cells. Fusion of VP22 to Apoptin, a protein that induces apoptosis in tumor cells but not in normal cells, might enhance the delivery of Apoptin. To analyze this hypothesis two fusion proteins of VP22 and full-length Apoptin were constructed, namely VP22-VP3 and VP3-VP22, and their apoptosis-inducing ability and intercellular spreading behavior were analyzed by transfection in tumor cells. While both of the Apoptin-VP22 fusion proteins retained the capacity to kill tumor cells, neither of them showed intercellular trafficking. To determine whether the presence of a nuclear localization signal in the C-terminus of Apoptin caused nuclear retention of the fusion protein and the subsequent lack of intercellular spreading, VP22 was fused to the biologically active N-terminal part (residues 1–69) of Apoptin (VP3n), which lacks the nuclear localization signal. However, analysis of the VP3n-VP22 fusion constructs gave no evidence of intercellular transport. A more careful inspection of different fractions of cell lysates expressing Apoptin with or without fusion to VP22 revealed that both the full-length Apoptin protein and its fusion with VP22 are insoluble. Despite the fact that VP3n was found to be soluble on its own, which could make it amenable to transport by VP22, the VP3n-VP22 fusion proteins were present exclusively in the insoluble fraction. We hypothesize that the N-terminal multimerization domain of Apoptin cooperates with VP22 to facilitate aggregation with cellular proteins, thereby inducing insolubility. From these results we conclude that, depending on the fusion partner, VP22 can have a negative effect on the solubility of fusion proteins, which consequently precludes intercellular trafficking. Such properties should be taken into account when establishing new VP22-mediated protein transduction systems.Abbreviations CAV Chicken anemia virus - DAPI 2,4-Diamidino-2-phenylindole - GFP Green fluorescent protein - NLS Nuclear localization signal     

Characterization of a newly established human acinic cell adenocarcinoma cell line (HACC) originating from the salivary gland: Morphological features and role of various growth factors on the growth of the HACC cell line

Human acinic cell adenocarcinoma cell (HACC) line was established from the pleural effusion that contains meta-static tumor cells of acinic cell adenocarcinoma of papillary and microcystic type originating from the parotid gland. The HACC cells grew in an adherent monolayer with a doubling time of 66 h. Implanted tumor of SCID mice revealed similar histologlcal findings to that of the primary tumor. The HACC cells produced mucin and expressed epithelial markers as well as α₁-antitrypsin and lysozyme, whereas salivary peptide P-C was expressed in cultured HACC cells but not In the primary and Implanted HACC cell tumors. S-100 protein was also expressed in both the primary tumor and HACC cell line. Neither amplification of common oncogenes nor expression of p53 was observed. The receptor for epidermal growth factor (EGF) was expressed, indicating EGF and transforming growth factor-α (TGF-α) enhanced the growth of the HACC line. Unexpectedly, tumor necrosis factor-α (TNF-α) also enhanced the growth of the HACC line significantly. However, there was no evidence of autocrine growth using these growth factors. In contrast, TGF-β1 inhibited the growth of the HACC cell line through apoptosis. The HACC cell line has features similar to both acinar and intercalated ductal cells of the salivary gland. Epidermal growth factor, TGF-α and TNF-α are potential growth factors for the HACC cell line. The HACC cell line may be a good model for studying the biological behavior of salivary gland neoplasms.     

Identification of two nuclear import signals in the alpha-gene product ICP22 of herpes simplex virus 1

The herpes simplex virus 1 (HSV-1) infected cell protein 22 (ICP22) is a multifunctional viral regulator that localizes in the nucleus of infected cells. ICP22 is required for optimal virus replication in certain cell types and is subject to extensive posttranslational modification. To map the signals in ICP22 which mediate its efficient nuclear localization, we investigated the nuclear import of fusion proteins comprising various fragments of ICP22 fused to green fluorescent protein (GFP) or beta-galactosidase (beta-Gal). These data demonstrated that ICP22 contains two independent regions with nuclear localization signal (NLS) activity. NLS1 maps to ICP22 amino acid position 16-31 and closely resembles the classical bipartite NLS of the type originally identified in nucleoplasmin. In contrast, NLS2 maps to ICP22 amino acid position 118-131 and contains multiple critical basic residues. Furthermore, fusion of both NLSs to chimeric glutathione-S-transferase (GST)-GFP protein and subsequent cytoplasmic microinjection of the respective transport substrates allowed us to monitor nuclear import in real-time. These data demonstrated that both ICP22-derived NLSs mediated efficient nuclear import with identical kinetics, resulting in complete nuclear accumulation of the chimeric transport cargoes at approximately 30 min postinjection. Finally, our data provide new insights into the domain structure of the multifunctional alpha-gene product ICP22 of HSV-1.     

Expression of HER-2/neu gene and protein in salivary duct carcinomas of parotid gland as revealed by fluorescence in-situ hybridization and immunohistochemistry

AIMS: Salivary duct carcinoma is a highly malignant salivary gland tumour with aggressive clinical behaviour, characterized by histological resemblance to invasive ductal carcinoma of the breast. Amplification of HER-2/neu oncogene and over-expression of its gene product have both prognostic and therapeutic implications in breast cancer. Recent report on salivary duct carcinomas for HER-2/neu using immunohistochemistry (IHC) has shown over-expression in most cases. However, correlation between IHC and molecular genetic analysis of HER-2/neu in salivary duct carcinoma has not yet been performed. METHODS AND RESULTS: We have now evaluated 11 cases of salivary duct carcinomas for HER-2/neu status using IHC and fluorescent in-situ hybridization (FISH). To our knowledge, this is the first molecular genetic analysis of HER-2/neu in salivary duct carcinoma. CONCLUSIONS: In immunohistochemistry, over-expression of HER-2/neu protein was identified as distinct membrane staining in most carcinoma cells in all our salivary duct carcinoma cases, while only four cases revealed an amplification of HER-2/neu gene by means of FISH analysis. Both amplified and non-amplified salivary duct carcinomas with strong immunohistochemical staining for HER-2/neu protein were associated with poor clinical outcome for the patients. Apparently, HER-2/neu protein over-expression could also be controlled by mechanisms other than gene amplification. In the group of salivary gland tumours other than salivary duct carcinoma, strong over-expression was detected only in three cases of carcinoma ex pleomorphic adenoma. Thus, over-expression of HER-2/neu protein is also a useful marker of malignant transformation in pleomorphic adenomas.     

Exploitation of the Herpes simplex virus translocating protein VP22 to carry influenza virus proteins into cells for studies of apoptosis: direct confirmation that neuraminidase induces apoptosis and indications that other proteins may have a role

Summary.  Previously, we have shown that apoptosis induced by influenza virus was inhibited by an anti-neuraminidase compound [4-guanidino-2, 3-dehydro-N-acetylneuraminic acid (GG167; Relenza; Zanamivir)], which does not enter cells, and acts at the attachment/entry phase of virus replication. Furthermore, a virulent virus, clone 7a, induced greater levels of apoptosis than the attenuated A/Fiji and had greater neuraminidase (NA) activity. To confirm more directly that NA induces apoptosis, the NA of clone 7a and A/Fiji was expressed fused to the Herpes simplex virus tegument coat protein VP22, transfected into HeLa cells and the level of apoptosis determined. VP22 translocates between cells via the medium thus allowing expressed proteins to transfer to a larger number of cells than those originally transfected. Clone 7a NA fused to VP22 induced a significant level of apoptosis whereas A/Fiji NA/VP22 did not, confirming that NA activity is an important determinant of apoptosis acting during fusion protein translocation between cells. Furthermore, the induction of apoptosis was abrogated by antibody to transforming growth factor-β, which is activated by NA. This approach also showed that VP22/NS1 proteins of both clone 7a and A/Fiji induced apoptosis when expressed alone but inhibited double stranded RNA-induced apoptosis suggesting that this protein may have a dual mode of action. Also, the M1 and M2 proteins of both viruses induced apoptosis but their NP proteins did not. Received June 27, 2001; accepted December 10, 2001     

Effect of Bcl-2 antisense oligonucleotide on drug-sensitivity in association with apoptosis in undifferentiated thyroid carcinoma

Although attempts have been made to treat undifferentiated thyroid carcinoma using multidisciplinary therapeutic procedures including surgery, radiotherapy, and chemotherapy, the prognosis of undifferentiated thyroid carcinoma remains quite poor. New approaches to increase the sensitivity of patients to anticancer drugs and radiation will be needed to improve the survival rate for undifferentiated thyroid carcinoma. We examined the effect of Bcl-2 antisense oligonucleotide on drug-sensitivity in association with apoptosis in the 8305C undifferentiated thyroid carcinoma cell line. The drug sensitivity was evaluated by MTT assay for 48 h, while apoptosis was assessed according to the formation of internucleosomal DNA ladders. The Bcl-2 antisense was introduced into 8305C cells by using a 18-mer phosphorothioate oligonucleotide by lipopolyamine-mediated transfection twice for 12 h. The expression of apoptosis genes was assessed by Western blotting. The 8305C cells were sensitive to adriamycin (ADM), mitomycin (MMC), docetaxel (TXT), and paclitaxel (TXL), showing mean IC50 values of 0.72, 1.1, 1.3, and 4.1 microM, respectively. In contrast, the 8305C cells were resistant to cisplatin (CDDP) and 5-fluorouracil (5-FU), with mean IC50 values of 42.0 and 48.0 microM, respectively. Treatment with Bcl-2 antisense suppressed the protein level of Bcl-2 in 8305C cells in a dose-dependent manner up to 1.0 microM. Drug-sensitivity was increased by pretreatment with Bcl-2 antisense as assessed by the IC50 (x-fold): 0.48 (1.5-fold) in ADM; 0.42 (2.6-fold) in MMC, 0.56 (2.3-fold) in TXT, 1.5 (2.7-fold) in TXL, 8.6 (4.9-fold) in CDDP, and 25.0 (1.9-fold) in 5-FU, respectively. The increased drug-sensitivity was associated with the induction of apoptosis-related proteins, Fas, caspase 8, cytochrome c, caspase 3, and to subsequent apoptosis, as determined by the formation of internucleosomal DNA ladders and PARP in the treated cells. Susceptibility in apoptotic cell death following treatment with anticancer drugs was associated with induction of apoptosis-related genes in undifferentiated thyroid carcinoma cells, and induction of apoptosis was enhanced by pretreatment with Bcl-2 antisense oligonucleotide. These results imply a potential new strategy targeting an antiapoptotic protein, Bcl-2, by its antisense oligonucleotide for enhancement of chemotherapeutic efficacy in undifferentiated thyroid carcinomas.     

SM22α对结直肠癌细胞侵袭和迁移能力的影响

目的:探究平滑肌22α蛋白(SM22α)对结直肠癌细胞侵袭和迁移能力的影响,并探讨其分子机制。方法:通过慢病毒转染人结直肠癌细胞HCTL16构建SM22α过表达细胞,应用细胞划痕实验检测细胞迁移能力的变化;Transwell小室检测细胞侵袭和迁移能力的变化;使用RT-qPCR检测细胞SM22αmRNA表达的改变;通过Western blot法检测细胞外信号调节激酶(ERK)、p-ERK、基质金属蛋白酶9(MMP-9)和SM22α蛋白水平。结果:成功构建HCT116过表达SM22α细胞;SM22α过表达细胞的侵袭和迁移能力减弱(P0.05);SM22α过表达抑制p-ERK和MMP-9的蛋白水平(P0.05)。结论:SM22α通过抑制ERK/MMP-9信号通路调节结直肠癌细胞侵袭和迁移能力。     

腺病毒介导的RNA干涉对乳腺癌SKBR3细胞HER2的下调及生长抑制效应

目的:探讨采用腺病毒做为载体介导基于RNA干涉的针对高HER2肿瘤的基因治疗的可能性。方法:构建HER2-绿色荧光蛋白融合蛋白表达质粒pHER2-GFP,并与9种针对HER2不同靶序列的siRNA表达质粒分别共转染CHO-K1细胞,根据荧光蛋白表达量从中筛选出沉默效率最高的质粒。将筛选出的质粒转染HER2高表达乳腺癌SKBR3细胞,检测它们对HER2表达的影响。随后,将siRNA转录单元克隆入腺病毒载体,成功包装病毒后感染SKBR3细胞,再次测定其下调HER2的效应及其对细胞生长的影响。结果:2种有效下调HER2表达的质粒被筛选出来。将此2种质粒所含siRNA转录单元包装入腺病毒后仍然保持了原有的基因沉默效应。HER2下调增加了SKBR3细胞中G1期细胞的比例,并且诱导部分细胞凋亡。MTT和细胞长期增殖抑制实验表明腺病毒介导的RNA干涉抑制了SKBR3细胞生长。结论:重组腺病毒介导的RNA干涉能够下调HER2的表达并且对高表达HER2的乳腺癌细胞有生长抑制作用。     

Radioprotective effect of heat shock protein 25 on submandibular glands of rats

Irradiation (IR) is a fundamental treatment modality for head and neck malignancies. However, a significant drawback of IR treatment is irreversible damage of salivary gland in the IR field. In the present study, we investigated whether heat shock protein (HSP) 25 could be used as a radioprotective molecule for radiation-induced salivary gland damage in rats. HSP25 as well as inducible HSP70 (HSP70i) that were delivered to the salivary gland via an adenoviral vector significantly ameliorated radiation-induced salivary fluid loss. Radiation-induced apoptosis, caspase-3 activation, and poly(ADP-ribose) polymerase cleavage in acinar cells, granular convoluted cells, and intercalated ductal cells were also inhibited by HSP25 or HSP70i transfer. The alteration of salivary contents, including amylase, protein, Ca+, Cl-, and Na+, was also attenuated by HSP25 transfer. Histological analysis revealed almost no radiation-induced damage in salivary gland when HSP25 was transferred. Aquaporin 5 expression in salivary gland was inhibited by radiation; and HSP25 transfer to salivary gland prevented this alteration. The protective effect of HSP70i on radiation-induced salivary gland damage was less or delayed than that of HSP25. These results indicate that HSP25 is a good candidate molecule to protect salivary gland from the toxicity of IR.