Methamphetamine use shortens telomere length in male adults and rats.

BACKGROUND: Methamphetamine (MA) use increases the risk of age-related diseases. However, it remains uncertain whether MA use exhibits accelerated biological aging, as indicated by telomere length (TL), a proposed marker of aging. Here we conducted studies in both humans and rats to investigate the association between MA use and TL. METHODS: We recruited 125 male MA users and 66 healthy controls, aged 30-40 years. MA users were diagnosed using DSM-5 criteria and categorized into two groups: non-severe (n = 78) and severe (n = 47) MA use disorder (MUD). MA-treated conditioned place preference (CPP) rats were utilized to validate our clinical investigations. TL was assessed using real-time polymerase chain reaction. RESULTS: At clinical levels, MA users exhibited significantly shorter leukocyte TL compared to healthy controls. Among MA users, individuals with severe MUD had significantly shorter leukocyte TL than those with non-severe MUD. Importantly, both univariate and multivariate linear regression analyses demonstrated a negative association between the severity of MA use and leukocyte TL. In a rat model of MA-induced CPP, leukocyte TL was also significantly shortened after MA administration, especially in rats with higher CPP expression or reinstatement scores. CONCLUSION: MA use shortened TL, and the severity of MA use was negatively correlated with TL. These findings provide new insights into the pathophysiology of accelerated aging caused by MA use and may have implications for identifying biomarkers and developing novel treatment strategies for MUD.

[Prokaryotic expression and purification of human GST-Cdc25C fusion protein and preliminary detection of its function].

AIM: To clone prokaryotic expression vector of Cdc25C, purify the fusion protein of GST-Cdc25C, and identify its function preliminarily. METHODS: Human Cdc25C coding region was amplified from human mammary cDNA library by PCR, and cloned into the prokaryotic expression vector pGEX-KG. The fusion protein GST-Cdc25C was expressed in E.coli Rossate and purified by GST-Sepharose 4B beads. The function of purified GST-Cdc25C was identified by GST pull-down assay. RESULTS: The GST-Cdc25C recombinant plasmid was successfully obtained by double digestion identification. The inserted fragment was confirmed correctly by sequencing. SDS-PAGE and Western blot analysis showed that the fusion protein was expressed. The fusion protein of about M(r); 80 000 was successfully induced, and identified by SDS-PAGE and Western blot analysis. GST pull-down assay showed that GST-Cdc25C could interact with Chk2 which verified its known function. CONCLUSION: Cdc25C was successfully cloned and purified.

[Detect the PES1 expression with prepared monoclonal antibody].

AIM: To prepare anti-PES1 monoclonal antibody (mAb) and detect the PES1 expression in several kinds of human cancer cell lines and its tissue distribution in the adult rat. METHODS: pGEX-PES1(1-322aa) fusion protein was purified and inject-ed into mice for immunization. Anti-PES1 mAb was produced by cell fusion and screening after immunization. Anti-PES1 mAb was identified by Western blot. Several human cancer cell lines and different tissue samples of adult rat were detected the PES1 expressions with the mAb prepared. RESULTS: Aanti-PES1 mAb was determined to be specific to PES1 with Western blot analysis. PES1 were expressed in all kinds of breast, ovary, liver and lung cancer cell lines detected in different levels with prepared mAb. Pescadillo was obviously expressed in the breast and ovary but not other tissues of adult rat using prepared mAb. CONCLUSION: Anti-PES1 mAb was successfully prepared. PES1 may play an important role in the tumorigenicity and may also play a role in the pathway of estrogen since breast and ovary, the most important estrogen target organ of adult rat, obviously express pesca-dillo.

[SUMO-2/3 can covalently bind to progesterone receptor B to regulate its transcriptional activity].

OBJECTIVE: To investigate whether progesterone receptor B (PRB) can be sumoylated by SUMO-2/3 and the effect of sumoylation on PRB transcriptional activity. METHODS: SUMO-2/3 cDNA was amplified from MCF-7 cDNA and cloned into the eukaryotic expression vector pcDNA3-FLAG. The plasmid pXJ40-myc-PRB was cotransfected with pcDNA3FLAG-SUMO2, pcDNA3FLAG-SUMO3 or the mock control into 293T cells, and PRB sumoylation was detected by immunoprecipitation and Western blotting. The effect of PRB sumoylation on its transcriptional activity was determined using reporter luciferase assay. RESULTS: pcDNA3FLAG-SUMO2 and pcDNA3FLAG-SUMO3 vectors were successfully constructed. SUMO-2/3 could bind covalently to PRB and increase its transcriptional dependent on the presence of progesterone. CONCLUSION: PRB can be sumoylated by SUMO-2/3 and its function is regulated by this modification.

[Prokaryotic expression and purification of human histone-1 and its activity detection].

AIM: To construct the prokaryotic expression vector of human histone-1, obtain the purified GST-H1 protein, and detect its activity. METHODS: Human histone-1 coding region was amplified from human mammary cDNA library, and was inserted into prokaryotic expression vector pGEX-KG. The recombinant plasmid pGEX-KG-H1 was transformed into E.coli Rossate. The expressed product was purified by GST-Sepharose 4B beads and identified by SDS-PAGE and Western blot analysis. RESULTS: The DNA fragment of about 650 bp was successfully amplified by PCR, cloned into pGEX-KG, and identified by sequencing. The recombinant protein of about M(r); 52 000 was successfully induced, purified and tested well by Kinase assay. CONCLUSION: The recombinant protein of GST-H1 is obtained successfully, which lay the foundation for further research on cell cycle control.

[siRNA-mediated inhibition of ErbB2 expression and its effect on breast cancer cell growth].

AIM: To construct a vector of ErbB2 small interfering RNA(siRNA), and to investigate its effect on ErbB2 expression and the growth of ZR75-1 breast cancer cells. METHODS: Two ErbB2-siRNAs were designed and inserted into the pSliencer 2.1-U6 neo vector. After confirmed by restriction and DNA sequencing, siRNA vectors were co-transfected with the FLAG-ErbB2 expression vector into human embryonic kidney 293T cells, or transfected into SKBR3 and ZR75-1 breast cancer cells. The effects of siRNAs on the expression of ErbB2 were identified by Western blot and the proliferation of ZR75-1 cells was repressed. RESULTS: Two siRNAs could effectively inhibit the expression of exogenous and endogenous ErbB2 proteins, and could repress the growth of ZR75-1 cells. CONCLUSION: ErbB2 siRNAs effectively inhibit the expression of ErbB2, thus repressing the growth of ZR75-1 cells.

[Inhibition of the expression of FHL2 by RNA interference].

AIM: To construct the eukaryotic expression vector of small interfering RNA (siRNA) targeting human FHL2 and transfect it into human embryo kidney 293T cells to investigate the silencing effect of FHL2 siRNA on the expression of FHL2 gene. METHODS: Two FHL2 siRNAs were designed and inserted into pSliencer 2.1-U6 neo expression vector. Then human embryo kidney 293T cells were cotransfected with the recombinant plasmids and FLAG-tagged FHL2 expression vector. The silencing effect of FHL2 siRNAs on the expression of FHL2 gene was identified by Western blot. RESULTS: The expression vectors of FHL2 siRNAs were constructed and confirmed by DNA sequencing. Western blot showed that FHL2 siRNAs effectively inhibited expression of FHL2. CONCLUSION: The eukaryotic expression vectors of FHL2 siRNAs are constructed successfully. The siRNAs effectively inhibit the expression of FHL2.

[Molecular mechanisms of regulation of estrogen receptor a expression level in breast cancer].

Estrogen receptor alpha (ERalpha) plays an important role in breast cancer development and progression and thus becomes a useful molecular target for breast cancer therapy. ERalpha is differentially expressed in breast cancer patients. Moreover, ERalpha expression levels may change at different stages of breast cancer even for the same patient. ERalpha expression is closely associated with the effect of endocrine therapy and prognosis. The mechanisms underlying ERalpha expression are complicated, because ERalpha expression is regulated at different levels, including chromatin, transcriptional, post- transcriptional, translational, and post-translational levels. Many proteins modulate the transcription of ERalpha gene at the chromatin and transcriptional levels through direct or indirect interaction with the ERa promoter. Some microRNAs decrease ERalpha levels possibly by induction of the degradation of ERalpha mRNA and/or repression of the mRNA translation. At the post-translational level, many proteins regulate ERalpha protein levels through ubiquitin-proteosome pathway. This review focuses on molecular mechanisms of regulation of ERalpha expression at different levels.

[Expression of EYA2 in non-small cell lang cancer].

OBJECTIVE: To identify the expression of Drosophila Eyes Absent Homologue 2 (EYA2) in non-small cell lung cancer (NSCLC) and to investigate its correlation with clinical parameters. METHODS: 59 fresh specimens of lung cancer and paired normal lung tissue were obtained from 59 NSCLC cases treated in the department of thoracic surgery in our hospital from June 2006 to October 2007. Western blotting and immunohistochemistry were used to assay the specimens with goat anti-human EYA2 polyclone antibody. Clinicopathological parameters were collected and the correlation with EYA2 expression was subsequently analyzed. RESULTS: The expression of EYA2 was detected in cytoplasm and nucleus of the cancer cells, but mostly in cytoplasm. Western blotting and immunohistochemistry showed the expression of EYA2 in NSCLC was increased and correlated with pathological type, but not with gender, age, pTNM stage, histological differentiation and lymph node metastasis. EYA2 expression was significantly up-regulated in adenocarcinoma, while not changed in lung squamous cell carcinoma. CONCLUSION: The results of this study suggest that expression of EYA2 in lung adenocarcinoma is augmented. EYA2 is likely participating in the development of lung adenocarcinoma as a transcriptional activator.

[Construction of human Egr-1 promoter and its response to ionizing radiation in tumor cells].

AIM: To construct human Egr-1 promoter luciferase reporter system and study its activity induced by ionizing radiation. METHODS: Egr-1 promoter was obtained by human genomic PCR and cloned into pGL3-basic vector. After transfection of recombinant plasmid into human tumor cells, the Egr-1 promoter activity induced by ionizing radiation was detected by luciferase reporter assay. RESULTS: The luciferase reporter system of Egr-1 promoter was successfully constructed. The activity of Egr-1 promoter was substantially increased after different doses of IR and reached to the peak at the time point of 48 h after IR. CONCLUSION: The Egr-1 promoter was constructed in this study showed IR inducible activity in tumor cells, laying foundation for the research of radiation. mediated gene therapy.

High mobility group box-1 protein acts as a coactivator of nuclear factor of activated T cells-2 in promoting interleukin-2 transcription.

High mobility group box-1 protein, an abundant and conserved constituent of vertebrate nuclei, has recently been reported to be an endogenous immune signal [Rovere-Querini P, Capobianco A, Scaffidi P, Valentinis B, Catalanotti F, Giazzon M, et al. HMGB1 is an endogenous immune adjuvant released by necrotic cells. EMBO Reports 2004;5:825-30]. High mobility group box-1 protein can trigger the release of interleukin-2 and interleukin-12 from lymphocytes. However, at present the underlying mechanism remains unknown. It has been clarified that nuclear factor of activated T cells-2 transduces most immunological signals in T cells and modulates the production of interleukin-2. So it is natural that we asked whether high mobility group box-1 protein could promote production of interleukin-2 in a nuclear factor of activated T cells-2-dependent way. Our experiments firstly showed that high mobility group box-1 protein could bind to nuclear factor of activated T cells-2 in vivo and in vitro. High mobility group box-1 protein cotransfection markedly upregulated the transcription activity of nuclear factor of activated T cells-2 in promoting interleukin-2 reporter gene transcription, which was demonstrated to be dose-dependent. Cotransfection of high mobility group box-1 protein and nuclear factor of activated T cells-2 induced an 18.4-time increase of interleukin-2 activity in 293T cells and a 117.7-time increase in Hela cells. Moreover, inhibition of either high mobility group box-1 protein or nuclear factor of activated T cells -2 expression by sRNAi led to significant decrease of transcription activity of interleukin-2 reporter gene, suggesting that high mobility group box-1 protein and nuclear factor of activated T cells-2 both take important roles in facilitating interleukin-2 transcription, and high mobility group box-1 protein could act as a coactivator for nuclear factor of activated T cells-2 in enhancing transcription of interleukin-2. This discovery has not been reported elsewhere, and helps to understand the newly highlighted immunological role of high mobility group box-1 protein.

[Establishment of estrogen receptor alpha trans-activation system].

OBJECTIVE: To construct estrogen receptor alpha (ERalpha) trans-activation system. METHODS: The full length ERalpha and its different function regions [(transcriptional activation function 1 (AF1), DNA binding domain (DBD), and transcriptional activation function 2 (AF2)] were amplified from pcDNA3-ERalpha by PCR and cloned into the pGAL vector. The expressions of the recombinant plasmids constructed were detected via immunoblotting. The 293T cells transfected with recombinant plasmids of full length ERalpha, its different function regions and empty vector were divided into 5 groups; each group was divided into 2 parts which were treated with or without estrogen (E(2)). The transcriptional activity of each group was detected in 293T cells after the recombinant plasmid was co-transfected with 0.2 microg of estrogen receptor element luciferase (ERE-LUC) and 0.1 microg of plasmid expressing beta-galactosidase and treated with or without 10 nmol/L E(2) for 24 hours. RESULTS: The full length ERalpha and its different function regions were expressed in the 293T cells. Compared with the empty pGAL vector, the transcription activities of full length ERalpha, AF1, AF2 and DBD recombinant plasmids were raised about 20.44 +/- 1.01, 2.09 +/- 0.11, 8.09 +/- 0.30 and 1.05 +/- 0.09 fold, respectively, with the induction of E(2) after transfection in the 293T cells. CONCLUSION: The trans-activation system of ERalpha has been successfully established.

[Effects of trichostatin A on the interaction between HBx and histone deacetylase protein 1].

OBJECTIVES: To study the effects of trichostatin A (TSA) on protein-protein interaction between HBx and histone deacetylase protein 1 (HDAC1). METHODS: Both HBx and HDAC1 expressing vectors were constructed by the method of routine molecular cloning. The expression of HBx and HDAC1 were observed by Western blot assay. The protein-protein interaction was tested between HBx and HDAC1 by GST pull-down in vitro as well as co-immunoprecipitation in vivo. RESULTS: Both HBx and HDAC1 expressing vectors were successfully constructed. Protein-protein interaction between HBx and HDAC1 existed both in vitro and in vivo. TSA, an inhibitor of HDAC1, had no effect on the interaction between HBx and HDAC1. CONCLUSIONS: HBx interacts with HDAC1 in vivo and in vitro in a non- TSA dependent way.

The relationship between the structure of dermatan sulfate derivatives and their antithrombotic activities.

To study the relationship between the structure of dermatan sulfate (DS) derivatives and their anti-thrombotic activities, DS-derived oligosaccharides (with different structures and relative molecular weight (M(r))) were prepared, and the effects of the DS-derived oligosaccharides on the activities of heparin cofactor II (HCII), activated protein C (APC), blood platelet, and vascular endothelial cells were studied. The major disaccharides of DS and polysulfated dermatan sulfate (PSDS) were IdoA-1-->3-GalNAc-4-OSO(3) and IdoA-2OSO(3)-1-->3-GalNAc4, 6-diOSO(3), respectively. The results showed that the consequence of the thrombotic inhibitory effects of DS and its derivatives were as follows: PSDS>low molecular weight polysulfated dermatan sulfate (LPSDS)>DS. Both DS and PSDS inhibited platelet aggregation in the concentration-dependent manner, and the IC(50) value of DS and PSDS is 12.7+/-1.3 and 28.6+/-0.9 mg/mL, respectively. DS oligosaccharides (DSOSs) and PSDS oligosaccharides (PSDSOSs) both significantly inhibited P-selectin expression on platelet surface (P<0.01), while DSOSs have no different effect compared with PSDSOSs. DSOSs and PSDSOSs significantly enhanced the activity of HCII in inhibiting thrombin in the plasma. The most active PSDSOS was PSDSOS(1) with M(r) of 4959, which enhanced the HCII activity by 91% (P<0.01). The experiments on APC activity showed that DS and its derivatives enhanced APC activity. The most active PSDSOS was PSDSOS(3) with M(r) of 2749, which enhanced the APC activity to 331+/-27% (P<0.01). DSOSs and PSDSOSs enhanced tissue plasminogen activator (t-PA) activity and reduced the plasminogen activator inhibitor (PAI) activity from cultured human umbilical vein endothelial cells (HUVEC), resulting in the ratio of t-PA/PAI going up. PSDSOSs which have the same M(r) as DSOSs produced more active effects in above assays, except for platelet aggregation.

[Preparation of antibody against Memo protein and analysis of expression profile of Memo in mouse tissues].

AIM: To prepare and characterize antibody against Memo protein and to detect the tissue distribution of Memo in mice. METHODS: Fusion protein GST-Memo was expressed and purified, and polyclonal antibody against Memo was prepared by immunizing mice. A FLAG-tagged eukaryotic expression vector pcDNA3-FLAG-Memo was constructed. The specificity of the antibody was detected by Western blot. RESULTS: An eukaryotic expression vector pcDNA3-FLAG-Memo was obtained. The polyclonal antibody was found to be specific to Memo. Memo protein was widely expressed in mouse tissues using the obtained antibody in Western blot. CONCLUSION: Antibody specific to Memo has been successfully obtained, which provides useful tool for investigation into Memo-associated mechanisms of tumor metastasis and invasiveness.

[Effects of exogenous ER beta expression on the cell growth properties of MCF-7 breast cancer cell line].

OBJECTIVE: To study the effects of exogenous ER beta on the growth of breast cancer MCF-7 cells under different treatment. METHODS: An eukaryotic expression vector containing 1.6 kb of human entire coding sequence of ER beta (pCDNA3-ER beta) was transfected into human breast cancer MCF-7 cells using lipofectamine 2000. The biological activity of ER beta was detected with the luciferase reporter containing estrogen responsive element (ERE) and the expression of ER beta protein by Western blot. The growth properties of MCF-7, pCDNA 3-transfected MCF-7 and pCDNA 3-ER beta-transfected MCF-7 cells under different treatment, including E2 (17beta-estradiol) and 4-OHT (4-hydroxytamoxifen), were observed. RESULTS: A stronger activation of the reporter by ER beta in the presence of E2 was observed in the pCDNA 3-ER beta-transfected MCF-7 cells than in the pCDNA 3-transfected MCF-7 and in MCF-7 cells. Western blot analysis showed that the protein level of ER beta in the pCDNA 3-ER beta-transfected MCF-7 cells was markedly increased. Exogenous ER beta expression did not change the growth properties and the morphology of MCF-7 cells under normal condition. The pCDNA 3-ER beta-transfected MCF-7 cells proliferated at the same rate as naive cells in the presence of 4-OHT, whereas a strong inhibition of the proliferation of the pCDNA 3-ER beta-transfected MCF-7 cells in the presence of E2 was observed. CONCLUSION: Exogenous ER beta expression does not increase the resistance to 4-OHT, and a strong inhibition of the proliferation may occur in the presence of E2.

[An analysis of the features of HBx protein distributed in liver cells and its expression in E. coli].

OBJECTIVE: To investigate the features of HBx protein distributed in liver cells and its expression in E. coli. METHODS: The expression vectors encoding the full length HBx and its mutants were constructed by the routine molecular cloning method. HBx protein expression was detected using Western blotting. The distribution feature of HBx protein in liver cells was examined using the fluorescence confocal microscopy. A series of purified HBx fusion proteins were obtained by glutathione-sepharose 4B affinity chromatography. RESULTS: The expression vectors were successfully constructed for the full length HBx and its mutants. HBx was found distributed uniformly in the nuclei but granularly in the cytoplasm of the liver cells. Under optimal conditions, the mutant GST-HBx (72-120aa) was easily degraded. CONCLUSION: This study may provide a basis for further study on the biological function of HBx at the protein level.

[Expression of XBP-1 in breast cancer cell lines and its role in ERalpha signaling].

Estrogen receptor (ERalpha) plays an important role in the development and progression of breast cancer. Several recent studies have demonstrated that expression of human X-box binding protein 1 (XBP-1) is associated with ERalpha status in breast tumors and overexpressed in a subset of breast tumors. XBP-1 has two splicing variants, which were designated as XBP-1S and XBP-1U, respectively. However, little is known about the expression pattern of XBP-1S and XBP-1U in breast cancer cells and about their roles in ERalpha signaling. In this study, the expression of two splicing forms of XBP-1 was detected in breast cancer cell lines with RT-PCR. Estrogen response element (ERE) -containing luciferase reporter assay was used to determine the effects of XBP-1S and XBP-1U on the transcription activity of ERalpha in MDA-MB-435 breast cancer cells. The result showed that both XBP-1S and XBP-1U enhanced the transcription activity of ERalpha in a hormone-independent and dose-dependent manner and the activity of of XBP-1S is higher than that of XBP-1U. Enhancement of ERE-containing luciferase reporter gene expression by XBP-1S and XBP-1U was dependent on ERalpha. These data suggest that XBP-1S and XBP-1U may play important roles in breast cancer growth and progression through ERalpha signaling.

A novel eIF5A complex functions as a regulator of p53 and p53-dependent apoptosis.

Although eukaryotic translation initiation factor 5A (eIF5A) was originally designated as an "initiation factor," recent data have shown it to be also involved in apoptosis. However, the actual function of eIF5A in apoptosis is still unknown. In this study, we performed yeast two-hybrid screens to identify eIF5A-interacting proteins to help us understand the mechanisms of eIF5A. Our results demonstrated that eIF5A and syntenin could engage in a specific interaction both in vitro and in vivo and functioned collaboratively to regulate p53 activity. Our findings, for the first time, revealed a new biological activity for eIF5A as the regulator of p53. Overexpression of eIF5A or its EFP domain resulted in up-regulation of p53, and silencing eIF5A by small interfering RNA reduced the p53 protein level. Further analysis by reverse transcription PCR showed eIF5A-activated p53 transcription. The effect of eIF5A on p53 transcriptional activity was further demonstrated by the increasing expressions of p21 and Bax, well known target genes of p53. In contrast, a point mutant of eIF5A, hypusination being abolished, was revealed to be functionally defective in p53 up-regulation. Overexpression of eIF5A led to a p53-dependent apoptosis or sensitized cells to induction of apoptosis by chemotherapeutic agents. However, when eIF5A interacted with its novel partner, syntenin, the eIF5A-induced increase in p53 protein level was significantly inhibited. Therefore, eIF5A seems to be a previously unrecognized regulator of p53 that may define a new pathway for p53-dependent apoptosis, and syntenin might regulate p53 by balancing the regulation of eIF5A signaling to p53 for apoptosis.

Attenuation of estrogen receptor alpha-mediated transcription through estrogen-stimulated recruitment of a negative elongation factor.

Estrogen receptor alpha (ERalpha) signaling is paramount for normal mammary gland development and function and the repression of breast cancer. ERalpha function in gene regulation is mediated by a number of coactivators and corepressors, most of which are known to modify chromatin structure and/or influence the assembly of the regulatory complexes at the level of transcription initiation. Here we describe a novel mechanism of attenuating the ERalpha activity. We show that cofactor of BRCA1 (COBRA1), an integral subunit of the human negative elongation factor (NELF), directly binds to ERalpha and represses ERalpha-mediated transcription. Reduction of the endogenous NELF proteins in breast cancer cells using small interfering RNA results in elevated ERalpha-mediated transcription and enhanced cell proliferation. Chromatin immunoprecipitation reveals that recruitment of COBRA1 and the other NELF subunits to endogenous ERalpha-responsive promoters is greatly stimulated upon estrogen treatment. Interestingly, COBRA1 does not affect the estrogen-dependent assembly of transcription regulatory complexes at the ERalpha-regulated promoters. Rather, it causes RNA polymerase II (RNAPII) to pause at the promoter-proximal region, which is consistent with its in vitro biochemical activity. Therefore, our in vivo work defines the first corepressor of nuclear receptors that modulates ERalpha-dependent gene expression by stalling RNAPII. We suggest that this new level of regulation may be important to control the duration and magnitude of a rapid and reversible hormonal response.