Cancer stem cell fate determination: mito-nuclear communication.

Cancer stem cells (CSCs) are considered to be responsible for tumor recurrence and metastasis. Therefore, clarification of the mechanisms involved in CSC stemness maintenance and cell fate determination would provide a new strategy for cancer therapy. Unregulated cellular energetics has been accepted as one of the hallmarks of cancer cells, but recent studies have revealed that mitochondrial metabolism can also actively determine CSC fate by affecting nuclear stemness gene expression. Herein, from the perspective of mito-nuclear communication, we review recent progress on the influence of mitochondria on CSC potential from four aspects: metabolism, dynamics, mitochondrial homeostasis, and reactive oxygen species (ROS). Video Abstract.

Advances in neuroendocrine prostate cancer research: From model construction to molecular network analyses.

Prostate cancer is the most common cancer among men and has a high incidence and associated mortality worldwide. It is an androgen-driven disease in which tumor growth is triggered via ligand-mediated signaling through the androgen receptor (AR). Recent evidence suggests that the widespread use of effective AR pathway inhibitors may increase the occurrence of neuroendocrine prostate cancer (NEPC), an aggressive and treatment-resistant AR-negative variant; however, mechanisms controlling NEPC development remain to be elucidated. Various preclinical models have recently been developed to investigate the mechanisms driving the NEPC differentiation. In the present study, we summarized strategies for the development of NEPC models and proposed a novel method for model evaluation, which will help in the timely and accurate identification of NEPC by virtue of its ability to recapitulate the heterogeneity of prostate cancer. Moreover, we discuss the origin and the mechanism of NEPC. The understanding of the regulatory network mediating neuroendocrine differentiation presented in this review could provide valuable insights into the identification of novel drug targets for NEPC as well as into the causes of antiandrogenic drug resistance.

Monoamine oxidase A drives neuroendocrine differentiation in prostate cancer.

Neuroendocrine transdifferentiation (NED) of prostate cancer (PCa) is the main cause of failure of androgen receptor inhibitor treatment. However, the molecular mechanisms underlying the development of NEPC, especially treatment-induced NEPC, remain unclear. Emerging evidence indicates that elevated monoamine oxidase A (MAOA) contribute to the proliferation, cell stemness, and bone metastasis in PCa. Here, we generated an enzalutamide-induced NED cell model to assess the role of MAOA during NED. Overall, MAOA expression was significantly increased upon Enz long-term exposure and was required for neuroendocrine marker expression. In particular, Enz was found to induce NED via the MAOA/mTOR/HIF-1α signaling axis. Further analyses revealed that the MAOA inhibitor clorgyline(CLG) may bring multiple benefits to CRPC patients, including better therapeutic effect and delays NED. These findings suggest that MAOA may be an important target for the development of anti-NED therapies, thereby providing a novel strategy for the combined application of CLG and AR inhibitors in the clinic.

[Association between LMNA mutation and familial and idiopathic dilated cardiomyopathy patients in Xinjiang].

OBJECTIVE: To explore the association between LMNA gene mutation and familiar dilated cardiomyopathy (DCM) (FDCM) and idiopathic DCM (IDCM) in Uygurs and Hans people in Xinjiang area. METHODS: Peripheral blood samples were collected from 28 family member with FDCM and 123 sporadic patients with IDCM(56 Uygur patients and 67 Han patients), 80 Uygur and 80 Han people were chosen as normal controls. PCR was used to amplify the 12 exons of LMNA gene. The amplified products were sequenced and compared with the standard sequence in the NCBI to determine the mutation sites. RESULTS: Transmission of the allele C and T of rs4641 was similar in Han FDCM patients. One new variation(c.1714C>T) located at exon 10 of LMNA gene was identified in 1 Han patient with IDCM, this mutation caused an amino acid substitution (R572C). In Uygurs people, rs553016 polymorphism was significant different between IDCM and control groups (P < 0.05). Logistic regression revealed that rs553016 was an independent risk factor for Uygurs patients with IDCM (OR = 3.178, P = 0.035). CONCLUSIONS: LMNA rs4641 is not associated with FDCM of Hans people in Xinjiang while LMNA mutation is associated with IDCM and rs533106 polymorphism is an independent risk factor for Uygurs patients with IDCM.

[Progress in targeted inhibition of aerobic glycolysis combined with immunotherapy for renal cell carcinoma].

Tumor aerobic glycolysis is one of the main features of tumor metabolic reprogramming. This abnormal glycolytic metabolism provides bioenergy and biomaterials for tumor growth and proliferation. It is worth noting that aerobic glycolysis will not only provide biological materials and energy for tumor cells, but also help tumor cells to escape immune surveillance through regulation of immune microenvironment, thereby resisting tumor immunotherapy and promoting tumor progression. Based on the pathogenesis of renal cell carcinoma, this paper describes the characteristics of aerobic glycolysis, the effect of glycolytic metabolism on the immune microenvironment of renal cell carcinoma, the effect of glycolysis inhibitors on the immune microenvironment of renal cell carcinoma, and the prospect of glycolysis inhibitors combined with immune checkpoint inhibitors in the treatment of renal cell carcinoma.

Inhibition of FSP1: A new strategy for the treatment of tumors (Review).

Ferroptosis, a regulated form of cell death, is intricately linked to iron­dependent lipid peroxidation. Recent evidence strongly supports the induction of ferroptosis as a promising strategy for treating cancers resistant to conventional therapies. A key player in ferroptosis regulation is ferroptosis suppressor protein 1 (FSP1), which promotes cancer cell resistance by promoting the production of the antioxidant form of coenzyme Q10. Of note, FSP1 confers resistance to ferroptosis independently of the glutathione (GSH) and glutathione peroxidase­4 pathway. Therefore, targeting FSP1 to weaken its inhibition of ferroptosis may be a viable strategy for treating refractory cancer. This review aims to clarify the molecular mechanisms underlying ferroptosis, the specific pathway by which FSP1 suppresses ferroptosis and the effect of FSP1 inhibitors on cancer cells.

Interaction between the EPHB2 receptor and EFNB1 ligand drives gastric cancer invasion and metastasis via the Wnt/ß-catenin/FAK pathway.

The survival benefit for patients with gastric cancer (GC) is modest due to its high transfer potential. Targeted therapy for metastasis-related genes in GC may be a viable approach, however, inhibitors specifically targeting GC are limited. In this study, GC patient-derived xenografts (PDX) with metastatic burden were established via orthotopic transplantation. PCR-Array analysis of primary and metastatic tumors revealed EPH receptor B2 (EPHB2) as the most significantly upregulated gene. The interaction between the EPHB2 receptor and its cognate-specific EFNB1 ligands was high in GC and correlated with a poor prognosis. Fc-EFNB1 treatment increased the invasion and migration abilities of GC cells and induced a high EPHB2 expression. EPHB2 knockdown in GC cells completely abolished the ephrin ligand-induced effects on invasion and migration abilities. Signal transduction analysis revealed Wnt/ß-catenin and FAK as downstream signaling mediators potentially inducing the EPHB2 phenotype. In conclusion, the observed deregulation of EPHB2/EFNB1 expression in GC enhances the invasive phenotype, suggesting a potential role of EPHB2/EFNB1 compound in local tumor cell invasion and the formation of metastasis.

Mitochondrial DNA methylation is a predictor of immunotherapy response and prognosis in breast cancer: scRNA-seq and bulk-seq data insights.

Background: Alterations in Mitochondrial DNA methylation (MTDM) exist in many tumors, but their role in breast cancer (BC) development remains unclear. Methods: We analyzed BC patient data by combining scRNA-seq and bulk sequencing. Weighted co-expression network analysis (WGCNA) of TCGA data identified mitochondrial DNA methylation (MTDM)-associated genes in BC. COX regression and LASSO regression were used to build prognostic models. The biological function of MTDM was assessed using various methods, such as signaling pathway enrichment analysis, copynumber karyotyping analysis, and quantitative analysis of the cell proliferation rate. We also evaluated MTDM-mediated alterations in the immune microenvironment using immune microenvironment, microsatellite instability, mutation, unsupervised clustering, malignant cell subtype differentiation, immune cell subtype differentiation, and cell-communication signature analyses. Finally, we performed cellular experiments to validate the role of the MTDM-associated prognostic gene NCAPD3 in BC. Results: In this study, MTDM-associated prognostic models divided BC patients into high/low MTDM groups in TCGA/GEO datasets. The difference in survival time between the two groups was statistically significant (P<0.001). We found that high MTDM status was positively correlated with tumor cell proliferation. We analyzed the immune microenvironment and found that low-MTDM group had higher immune checkpoint gene expression/immune cell infiltration, which could lead to potential benefits from immunotherapy. In contrast, the high MTDM group had higher proliferation rates and levels of CD8+T cell exhaustion, which may be related to the secretion of GDF15 by malignant breast epithelial cells with a high MTDM status. Cellular experiments validated the role of the MTDM-associated prognostic gene NCAPD3 (the gene most positively correlated with epithelial malignant cell proliferation in the model) in BC. Knockdown of NCAPD3 significantly reduced the activity and proliferation of MDA-MB-231 and BCAP-37 cells, and significantly reduced their migration ability of BCAP-37 cell line. Conclusion: This study presented a holistic evaluation of the multifaceted roles of MTDM in BC. The analysis of MTDM levels not only enables the prediction of response to immunotherapy but also serves as an accurate prognostic indicator for patients with BC. These insightful discoveries provide novel perspectives on tumor immunity and have the potentially to revolutionize the diagnosis and treatment of BC.

Monoamine oxidase A (MAOA): A promising target for prostate cancer therapy.

Monoamine oxidase A (MAOA) is a mitochondrial enzyme that catalyzes the oxidative deamination of monoamine neurotransmitters and dietary amines. Previous studies have shown that MAOA is clinically associated with prostate cancer (PCa) progression and plays a key role in almost each stage of PCa, including castrate-resistant prostate cancer, neuroendocrine prostate cancer, metastasis, drug resistance, stemness, and perineural invasion. Moreover, MAOA expression is upregulated not only in cancer cells but also in stromal cells, intratumoral T cells, and tumor-associated macrophages; thus, targeting MAOA can be a multi-pronged approach to disrupt tumor promoting interactions between PCa cells and tumor microenvironment. Furthermore, targeting MAOA can disrupt the crosstalk between MAOA and the androgen receptor (AR) to restore enzalutamide sensitivity, blocks glucocorticoid receptor (GR)- and AR-dependent PCa cell growth, and is a potential strategy for immune checkpoint inhibition, thereby alleviating immune suppression and enhancing T cell immunity-based cancer immunotherapy. MAOA is a promising target for PCa therapy, which deserves further exploration in preclinical and clinical settings.

Synergistic inhibition of the growth of MDA-MB-231 cells in triple-negative breast cancer by salinomycin combined with 17-AAG and its mechanism.

Salinomycin (SAL), a typical ion carrier antibiotic, inhibits tumor growth and metastasis by inducing apoptosis or autophagy in cancer or cancer stem cells and thus overcomes drug resistance. 17-allylamino-17-demethoxygeldanamycin (17-AAG), a heat shock protein Hsp90 competitive inhibitor, also has a role in inhibiting tumor development. However, their combination on the growth of breast cancer cells and its specific mechanism remains to be elucidated. The present study tested the influence of SAL and 17-AAG on cell growth, apoptosis and autophagy by MTT assays, Annexin V-FITC and propidium iodide double staining assay and immunoelectron microscopy. The influence of SAL and 17-AAG on proteomics was investigated by isobaric tag for relative and absolute quantitation. It was found that SAL combined with 17-AAG synergistically inhibited the cell growth and induced the apoptosis in a concentration-dependent manner, with the expression of caspase 3 and Bcl-2 were decreased while the expression of Bax was increased. In addition, SAL combined with 17-AAG inhibited autophagy, with the expression of microtubule-associated protein 1 light chain 3, Beclin1, p62 being decreased. Mechanistically, SAL combined with 17-AAG synergistically inhibited the reactive oxygen species/JNK signaling pathway. In conclusion, SAL combined with 17-AAG had a synergistic inhibitory effect on cell growth of breast cancer via inducing apoptosis and inhibiting autophagy. The present study might provide a new strategy for potential clinical application of SAL as a new anti-tumor drug especially as a drug combination with other molecular targeting therapeutics.

Strategies for the Construction of Mouse Models With Humanized Immune System and Evaluation of Tumor Immune Checkpoint Inhibitor Therapy.

Immunotherapy has been used as a first-line treatment for a variety of advanced tumors, allowing remarkable progress to be made in cancer treatment. Nonetheless, only a small number of patients can benefit from immune checkpoint inhibitor monotherapy. To improve the effect of immunotherapy, the underlying mechanism of combination therapy was investigated in the context of an intact human tumor immune microenvironment using mice with a human immune system (HIS) bearing human tumors. Herein, we summarize and discuss strategies for the development and use of HIS mice models in tumor immunotherapies. Most importantly, this review proposes a method of t11umor identification and classification in HIS mice based on the tumor-infiltrating lymphocytes and PD-L1 expression, and according to this classification, we propose different combination treatment strategies that can be utilized to enhance the effect of immunotherapy. Thus, we provide effective experimental schemes for tumor immunotherapy in HIS mice models.

A promising cancer gene therapy agent based on the matrix protein of vesicular stomatitis virus.

The matrix (M) protein of vesicular stomatitis virus (VSV) plays a key role in inducing cell apoptosis during infection. To investigate whether M protein-mediated apoptosis could be used in cancer therapy, its cDNA was amplified and cloned into eukaryotic expression vector pcDNA3.1(+). The recombinant plasmid or the control empty plasmid pcDNA3.1(+) was mixed with cationic liposome and introduced into various tumor cell lines in vitro, including lung cancer cell LLC, A549, colon cancer cell CT26 and fibrosarcoma cell MethA. Our data showed that the M protein induced remarkable apoptosis of cancer cells in vitro compared with controls. Fifty micrograms of plasmid in a complex with 250 microg cationic liposome was injected intratumorally into mice bearing LLC or MethA tumor model every 3 days for 6 times. It was found that the tumors treated with M protein plasmid grew much more slowly, and the survival of the mice was significantly prolonged compared with the mice treated with the control plasmid. In MethA fibrosarcoma, the tumors treated with M protein plasmid were even completely regressed, and the mice acquired longtime protection against the same tumor cell in rechallenge experiments. Both apoptotic cells and CD8(+) T cells were widely distributed in M protein plasmid-treated tumor tissue. Activated cytotoxic T lymphocytes (CTLs) were further detected by means of (51)Cr release assay in the spleen of the treated mice. These results showed that M protein of VSV can act as both apoptosis inducer and immune response initiator, which may account for its extraordinary antitumor effect and warrant its further development in cancer gene therapy.

[Apoptosis of colon carcinoma cells of mice induced by vesicular stomatitis virus matrix protein in vitro].

OBJECTIVE: To test the inhibitive effect of the matrix protein of vesicular stomatitis virus (VSV) on the proliferation of colon carcinoma cells of mice in vitro. METHODS: The plasmid pcDNA3. 1-M encoding M protein of vesicular stomatitis viruses was transfected with lipofectamine 2000 into the colon carcinoma (CT26) cells of mice. The expression of VSV-M protein in the CT26 cells was detected by Western blot. The effect of vesicular stomatitis virus (VSV) matrix protein on the proliferation and apoptosis of colon carcinoma cells was measured by MTT, PI stainning and flow cytometry. RESULTS: The plasmid expressed M protein in the CT26 cells. Cytopathic effect was shown in the CT26 cells with transfected pcDNA3.1-M. The proliferation of the CT26 cells was suppressed significantly in vitro (76.4%, P < 0.05). The M protein induced apoptosis of the CT26 cells (80.2%), which was higher than'that of the controls (P < 0.05). CONCLUSION: The eukaryotic expression plasmid pcDNA3.1-M encoding M protein of vesicular stomatitis viruses induces apoptosis of CT26 cells, which has implications on the treatment of human colon cancer.

[Screening and identification of mesenchymal stem cell strains to secret mouse interleukin-12 mediated with lenti-viral vector].

OBJECTIVE: To screen the stable expression cell strains of mouse interleukin-12 (mIL-12) from mouse Mesenchymal Stem Cells (mMSCs) transfected with lenti-mIL-12 virus. METHODS: The mIL-12 cDNA was amplified from plasmid pORF-mIL-12 (Invivogen) by PCR. The cDNA was subcloned into pENTR 11 to generate recombinant plasmid pENTR-mIL-12. Then, pENTR-mIL-12 was homologously recombinated with pLenti6/V5-Dest. The recombinant was named as pLenti6/V5-mIL-12 and confirmed by PCR and DNA sequencing. The Lenti6/V5-mIL-12 virus was packaged using 293FT cells. The Lenti-mIL-12-MSC monoclone was picked from the mMSCs infected by the Lenti6/V5-mIL-12 virus using Blasticidin and verified by RT-PCR and ELISA. RESULTS: The recombinant pLenti6/V5-mIL-12 was constructed. The sequence of amplified mIL-12 gene was consistent with that reported in GenBank. By RT-PCR and ELISA, it was confirmed that the mIL-12 protein could be expressed and secreted into the supernatant of MSC strain culture. CONCLUSION: The recombinant mMSC strains lentivirally engineered to secret mIL-12 were obtained.

[Inhibitory effect of Trillium saponins on invasion and migration of HuH-7 cells by promoting human ß defensin-2 expression].

Objective To investigate the effect and mechanism of Trillium saponins on the invasion and migration of HuH-7 cells regulated by human ß-defensin 2 (HBD-2). Methods HuH-7 cells were treated with 0.5, 1.0, 2.0, 4.0 mg/L Trillium saponins. Cell proliferation was detected by MTT assay. TranswellTM chamber was used to measure cell invasion and migration. The levels of matrix metalloproteinase-2 (MMP2), HBD-2 and matrix metalloproteinase-9 (MMP9) were detected by Western blot analysis. HBD-2 small interfering RNA (siRNA) was transfected into HuH-7 cells. The interference effect of Trillium saponins treatment was verified by real-time quantitative PCR and Western blot analysis, and TranswellTM assay was used to detect cell invasion and migration. Results Except that 0.5 mg/L Trillium saponins had no effect on the proliferation of HuH-7 cells, the proliferation of HuH-7 cells was inhibited by all other doses of Trillium saponins. (0.5, 1.0) mg/L of Trillium saponins down-regulated the levels of MMP2 and MMP9 proteins, increased the level of HBD-2 protein and inhibited cell invasion, migration. HBD-2 siRNA transfection significantly reduced the level of HBD-2 in HuH-7 cells. Down-regulation of HBD-2 increased the invasive, migratory ability and increased the levels of MMP2 and MMP9 proteins in HuH-7 cells treated with Trillium saponins. Conclusion Trillium saponins can inhibit the invasion and migration of HuH-7 cells by promoting the expression of HBD-2.

Vesicular stomatitis virus matrix protein gene enhances the antitumor effects of radiation via induction of apoptosis.

Vesicular stomatitis virus (VSV) matrix (M) protein can directly induce apoptosis by inhibiting host gene expression when it is expressed in the absence of other viral components. Previously, we found that the M protein gene complexed to DOTAP-cholesterol liposome (Lip-MP) can suppress malignant tumor growth in vitro and in vivo; however, little is known regarding the biological effect of Lip-MP combined with radiation. The present study was designed to determine whether Lip-MP could enhance the antitumor activity of radiation. LLC cells treated with a combination of Lip-MP and radiation displayed apparently increased apoptosis compared with those treated with Lip-MP or radiation alone. Mice bearing LLC or Meth A tumors were treated with intratumoral or intravenous injections of Lip-MP and radiation. The combined treatment significantly reduced mean tumor volumes compared with either treatment alone in both tumor models and prolonged the survival time in Meth A tumor models and the intravenous injection group of LLC tumor models. Moreover, the antitumor effects of Lip-MP combined with radiation were greater than their additive effects when compared with the expected effects of the combined treatment in vivo. This study suggests that Lip-MP enhanced the antitumor activity of radiation by increasing the induction of apoptosis.

Lily extracts inhibit the proliferation of gastric carcinoma SGC-7901 cells by affecting cell cycle progression and apoptosis via the upregulation of caspase-3 and Fas proteins, and the downregulation of FasL protein.

The present study aimed to investigate the effect of alkaloids and carbinol extracts from lily on the proliferation of SGC-7901 cells, as well as the underlying mechanism. SGC-7901 cells were incubated with different concentrations of alkaloid or carbinol extracts for 24, 48 or 72 h. MTT assays were used to measure the inhibition rate of SGC-7901 cell proliferation. Inverted phase contrast and fluorescence microscopy was used to observe morphological changes of SGC-7901 cells. Flow cytometry was employed to detect cell cycle progression and apoptosis rates of SGC-7901 cells. Western blotting was performed to measure the expression of caspase-3, Fas and Fas ligand (FasL) proteins in SGC-7901 cells. The inhibition rate of SGC-7901 cell proliferation was significantly enhanced with increasing drug concentrations and time elapsed. Treatment with alkaloid or carbinol extracts deteriorated the morphology of SGC-7901 cells in a dose-dependent manner. Alkaloid and carbinol extracts arrested SGC-7901 cells in the G2/M phase, and induced apoptosis in a dose-dependent manner. Alkaloid and carbinol extracts enhanced caspase-3, and Fas expression, but reduced FasL expression in SGC-7901 cells. The present study demonstrated that alkaloids and carbinol extracts from lily inhibited the proliferation of gastric carcinoma SGC-7901 cells by arresting cells in the G2/M phase. The upregulation of caspase-3 and Fas proteins, and the downregulation of FasL protein may be an important mechanism for the induction of SGC-7901 cell apoptosis.

An in vitro study on the effects of the combination of salinomycin with cisplatin on human gastric cancer cells.

The present study aimed to investigate the anticancer effects of cisplatin (DDP) combined with salinomycin (SAL) on the gastric cancer cell line SGC­7901, as well as to explore the mechanisms underlying their actions. An MTT assay was used to evaluate the inhibitory effects of SAL, DDP and their combination on gastric cancer cell proliferation. Morphological alterations of cancer cells following treatment were observed under an inverted phase­contrast microscope and a fluorescence microscope. Cell cycle progression and apoptosis were analyzed using flow cytometry. The expression of nuclear factor (NF)­κB p65 and Fas protein ligand (L) in cancer cells was assessed using immunocytochemistry. The present results demonstrated that the combination of SAL and DDP significantly inhibited the proliferation (P<0.05) and altered the morphological characteristics of SGC­7901 cells, thus suggesting that SAL may enhance the susceptibility of gastric cancer cells to DDP. In addition, treatment with a combination of SAL and DDP resulted in S phase­arrest and increased the apoptotic rate of SGC­7901 cells. Furthermore, marked FasL upregulation and NF­κB p65 downregulation were observed in cancer cells treated with the combination of SAL and DDP. The results of the present study demonstrated that the combination of SAL and DDP induced the apoptosis of human gastric cancer cells, and suggested that the underlying mechanism may involve the upregulation of FasL and downregulation of NF­κB p65.

Effects of salinomycin and 17­AAG on proliferation of human gastric cancer cells in vitro.

The aim of the present study was to investigate the effects and mechanisms of 17­AAG combined with salinomycin treatment on proliferation and apoptosis of the SGC­7901 gastric cancer cell line. An MTT assay was used to detect the proliferation of SGC­7901 cells. Morphological alterations of cells were observed under inverted phase­contrast and fluorescence microscopes. Cell cycle and apoptosis were assessed by flow cytometry analysis. The protein expression of nuclear factor (NF)­κB p65 and Fas­ligand (L) were evaluated by immunocytochemistry. Salinomycin with a concentration range of 1­32 µmol/l was demonstrated to inhibit growth of SGC­7901 cells effectively, affect the morphology and apoptosis rate of cells, and arrest SGC­7901 cells in S phase. Furthermore, salinomycin significantly increased the protein expression of Fas­L and decreased the protein expression of NF­κB p65. The alterations in SGC­7901 cells co­treated with salinomycin and 17­AAG were more significant compared with cells treated with one drug only. In conclusion, the individual use of salinomycin and combined use with 17­AAG may significantly inhibit SGC­7901 gastric cancer cell proliferation and induce cell apoptosis. The potential mechanisms may be associated with upregulation of Fas­L and downregulation of NF­κB. These results provide a basis for the potential use of salinomycin in gastric cancer treatment.

[Construction of mammalian co-expression plasmid pIRES -LMP1-HSP90 beta and its expression in vitro].

OBJECTIVE: This study sought to clone Epstein-Barr virus latent membrane protein 1 (LMP1) and heat shock protein 90 beta (HSP90 beta) of nasopharyngeal carcinoma (NPC), to construct the mammalian co-expression plasmid pIRES-LMP1-HSP90 beta, and to detect the expression of the plasmid in vitro. METHODS: Total RNA was isolated from human NPC by cloning technique, their cDNA fragments of LMP1 gene and HSP90 beta gene were gained by RT-PCR, and their cDNA fragments were constructed into the mammalian co-expression plasmid vector pIRES. The inserted target genes in the mammalian co-expression plasmid were verified by nucleotide sequencing. COS cell line was transfected with this mammalian co-expression plasmid using lipofectin reagent. The expression of LMP1 and HSP90 beta molecules were detected by RT-PCR and Western blot technique. RESULTS: The mammalian expression plasmid pIRES-LMP1-HSP90 beta was obtained by cloning technique. The nucleotide sequences of LMP1 gene and HSP90 beta gene in this mammalian co-expression plasmid had high homology with EBV-LMP1 (100%) and human HSP90 beta (100%) respectively. After transfection with this mammalian co-expression plasmid, the LMP1 and HSP90 beta molecules were expressed in COS cells. CONCLUSION: The constructed mammalian co-expression plasmid pIRES-LMP1-HSP90 beta can express LMP1 and HSP90 beta molecules in vitro at the same time.