Structural basis of human mpox viral DNA replication inhibition by brincidofovir and cidofovir.

Mpox virus has wildly spread over 108 non-endemic regions in the world since May 2022. DNA replication of mpox is performed by DNA polymerase machinery F8-A22-E4, which is known as a great drug target. Brincidofovir and cidofovir are reported to have broad-spectrum antiviral activity against poxviruses, including mpox virus in animal models. However, the molecular mechanism is not understood. Here we report cryogenic electron microscopy structures of mpox viral F8-A22-E4 in complex with a DNA duplex, or dCTP and the DNA duplex, or cidofovir diphosphate and the DNA duplex at resolution of 3.22, 2.98 and 2.79 Å, respectively. Our structural work and DNA replication inhibition assays reveal that cidofovir diphosphate is located at the dCTP binding position with a different conformation to compete with dCTP to incorporate into the DNA and inhibit DNA synthesis. Conformation of both F8-A22-E4 and DNA is changed from the pre-dNTP binding state to DNA synthesizing state after dCTP or cidofovir diphosphate is bound, suggesting a coupling mechanism. This work provides the structural basis of DNA synthesis inhibition by brincidofovir and cidofovir, providing a rational strategy for new therapeutical development for mpox virus and other pox viruses.

Glycocholic acid aggravates liver fibrosis by promoting the up-regulation of connective tissue growth factor in hepatocytes.

AIMS: The precise role of bile acid in the progression of liver fibrosis has yet to be elucidated. In this study, common bile duct ligation was used as an in vivo mouse model for the evaluation of bile acids that promote liver connective tissue growth factor expression. MAIN METHODS: Primary rat and mice hepatocytes, as well as primary rat hepatic stellate and HepaRG cells were evaluated as in vitro models for promoting the expression of connective tissue growth factor by bile acids. KEY FINDINGS: Compared with taurochenodeoxycholic acid, glycochenodeoxycholic acid, and taurocholic acid, glycocholic acid (GCA) most strongly promoted the secretion of connective tissue growth factor in mouse primary hepatocytes, rat primary hepatocytes and HepaRGs. GCA did not directly promote the activation of hepatic stellate cells. The administration of GCA in mice with ligated bile ducts promotes the progression of liver fibrosis, which may promote the yes-associated protein of hepatocytes into the nucleus, resulting in the hepatocytes secreting more connective tissue growth factor for hepatic stellate cell activation. In conclusion, our data showed that GCA can induce the expression of connective tissue growth factor in hepatocytes by promoting the nuclear translocation of yes-associated protein, thereby activating hepatic stellate cells. SIGNIFICANCE: Our findings help to elucidate the contribution of GCA to the progression of hepatic fibrosis in cholestatic disease and aid the clinical monitoring of cholestatic liver fibrosis development.

Influence of Zhuanggu Guanjie Pill on Seven Cytochrome P450 Enzymes Based on Probe Cocktail and Pharmacokinetics Approaches.

BACKGROUND: The use of herbal medicines has tremendously increased over the past few decades. Case reports and controlled clinical investigations of herbal-drug interactions have been reported. Since Cytochrome P450 (CYP) enzymes play an important role in drug interactions. The evaluation of the influence of herbal medicines on the activities of CYPs is beneficial to promote scientific and rational clinical use of herbal medicines. OBJECTIVE: Herein, we aimed to develop and validate a method to simultaneously quantify seven CYP cocktail probe drugs consisting of phenacetin (PNC), bupropion (BPP), losartan potassium (LK), omeprazole (OMP), dextromethorphan (DM), chlorzoxazone (CZZ) and midazolam (MDZ) and their respective metabolites in a single acquisition run and use this method to evaluate the influence of Zhuanggu Guanjie Pill (ZGGJP) on seven CYPs. METHODS: A cost-effective and simple UHPLC-(±)ESI-MS/MS method for simultaneous determination of seven probe drugs and metabolites in rat plasma was developed and validated. Male and female rats were randomly divided into three groups and treated with 1.2 g/kg/d ZGGJP, 5 g/kg/d ZGGJP and 0.5% CMC-Na for 14 consecutive days. After 24 h of the last administration, all rats were administrated orally with probe drugs. The influence of ZGGJP on the CYPs was carried out by comparing the metabolic ratio (Cmax, AUC0-t) of metabolites/probe drugs in rats. RESULTS: The calibration curves were linear, with correlation coefficient > 0.99 for seven probe drugs and their corresponding metabolites. Intra- and inter-day precisions were not greater than 15% RSD and the accuracies were within ±15% of nominal concentrations. The ZGGJP showed significant inductive effect on CYP1A2, CYP2B6, CYP2C9 and CYP3A in male and female rats. CONCLUSION: ZGGJP had inductive effects on CYP1A2, CYP2B6, CYP2C9 and CYP3A in male and female rats.

Proteomics analysis reveals novel insights into the mechanism of hepatotoxicity induced by Tripterygium wilfordii multiglycoside in mice.

Tripterygium wilfordii multiglycoside (GTW), extracted and purified from the peeled roots of T. wilfordii Hook.f. (TwHF), is a well-known traditional Chinese medicine and applied to various autoimmune diseases clinically. However, it has been reported to cause severe liver injury. At present, the mechanism underlying GTW-induced hepatotoxicity remain poorly defined. Here, we evaluated the effects of GTW on mouse liver and elucidated the associated mechanisms via label-free proteomics combined with bioinformatics analysis. Male C57BL/6J mice were randomly divided into normal group, a low-dose GTW (70 mg/kg) group and a high-dose GTW (140 mg/kg) group. After 1-week administration, GTW dose-dependently induced hepatotoxicity. Further analysis showed that GTW could act on the intestinal immune network for IgA production pathway, which plays an important role in maintaining intestinal homeostasis and influences the crosstalk between gut and liver. Western blots confirmed that GTW could decrease pIgR protein expression in the liver and ileum, and, as a result, the secretion of IgA into gut lumen was reduced. Further validation showed that intestinal barrier integrity was impaired in GTW-treated mice, promoting bacteria transferring to the liver and triggering proinflammatory response. Our study demonstrated that gut-liver axis may play a vital part in the progression of GTW-induced hepatotoxicity, which provides guidance for basic research and clinical application of GTW.

Novel application of anti-human Fc nanobody for screening high-producing CHO cells for monoclonal antibody.

Animal-derived anti-IgG secondary antibodies are currently employed to stain and screen of human monoclonal antibody(mAb)-producing cells, but using animal-derived antibodies may raise the concerns of high cost, complicated operations and biological safety issues in biopharmaceutical manufacturing. Nanobodies(VHHs) are attractive forms of antibodies for their straightforward engineering and expression in both eukaryotic and prokaryotic systems. Using phage-displayed immune llama VHH library, we identified new anti-Fc VHHs that could bind to human Fc with high affinity. In GFP fusion format, the anti-Fc VHH-GFP generated dramatically stronger FACS signals than AF488 conjugated anti-IgG antibodies when used for staining mAb-producing CHO cells. Furthermore, preparative sorting of CHO cells based on anti-Fc VHH-GFP staining resulted in the enrichment of cell lines capable of synthesizing mAb at high productivity. This safe and cost-efficient anti-Fc VHH-GFP may optimize the process of generating highly productive cell lines for therapeutic mAb production compared to conventional animal-derived fluorescent antibodies.

Obeticholic acid aggravates liver injury by up-regulating the liver expression of osteopontin in obstructive cholestasis.

AIMS: Obeticholic acid (OCA) was approved for the treatment of primary biliary cholangitis (PBC) patients, as it can significantly improve the level of serum alkaline phosphatase. However, OCA-induced liver injury in PBC patients puts them at risk of acute chronic liver failure, thus limiting the clinical application of OCA. Osteopontin (OPN), an extracellular cell matrix molecule, is highly induced in many cholestatic liver diseases. Herein we explored whether liver injury exacerbation by OCA was related to OPN. MAIN METHODS: Bile duct ligation (BDL) mice were treated with OCA (40 mg/kg) to evaluate its effect on liver injury and OPN involvement. Enzyme-linked immunosorbent assay, western blot, immunohistochemistry, and other assays were used to detect OPN levels in serum and liver. Immunohistochemistry, and immunofluorescence, among other assays, were used to evaluate the extent of ductular reaction. The extent of fibrosis was also determined using various assays, such as immunohistochemistry, quantitative real-time PCR (qPCR), and hydroxyproline assays. KEY FINDINGS: OPN was overexpressed in the liver of BDL mice treated with OCA. OCA induced overexpression of OPN exacerbated ductular reaction, fibrosis, and liver inflammation, and reduced hepatocyte proliferation. SIGNIFICANCE: Upon liver injury, OCA upregulates the expression of OPN in the liver and accelerates disease progression. This mechanism helps explain the risk of liver damage associated with OCA.

Effects of Ambidextrous Leadership on Employees' Work Behavior: The Mediating Role of Psychological Empowerment.

The complexity of today's organizational environment increasingly requires leaders to think in a dynamic and flexible way to resolve contradictory issues. This study explored and compared the effects of servant leadership and authoritarian leadership on employees' work behavior from the perspectives of ambidextrous leadership theory and social exchange theory, and further examined the mediating role of psychological empowerment. In this study, 315 employees from state-owned communication companies in Shandong and Zhejiang Provinces in China were selected as subjects, and path analysis was used to test the hypotheses. The results showed that servant leadership positively predicted organizational citizenship behavior and task performance. While authoritarian leadership negatively predicted organizational citizenship behavior and positively predicted task performance, psychological empowerment mediated the relationship between the two leadership styles and organizational citizenship behavior and task performance. Moreover, psychological empowerment and organizational citizenship behavior played a multiple mediating role between the two leadership styles and task performance. The theoretical implications of these findings for advancing the ambidextrous leadership theory in Chinese organizational contexts and practical approaches for corporate managers to effectively use ambidextrous leadership style were discussed.

Preparation and properties of N-glycosylated chitosan/polyvinyl alcohol hydrogels for use in wound dressings.

Chitosan and its derivatives show potent biocompatibility, biodegradability, antimicrobial activity, hemostatic effects, and wound healing properties. Their application in wound dressings has garnered substantial research interest. In this work, we prepared a drug-loaded hydrogel by mixing N-glycosylated chitosan with polyvinyl alcohol (PVA), followed by loading of ofloxacin. A 2:1 volume ratio of chitosan to PVA was found to be optimal based on swelling and water evaporation rates. The slow-drug-release performance of the blended hydrogel was best when the ofloxacin loading was 5.0%. The ofloxacin-loaded hydrogel shows excellent antimicrobial properties in vitro and wound healing ability in an in vivo rabbit full-thickness excision wound model. The chitosan/PVA blended hydrogel has great potential for use in wound dressings and sustained drug release.

Investigating Derivatives of Tanshinone IIA Sulfonate Sodium and Chloroxine for Their Inhibition Activities against the SARS-CoV-2 Papain-like Protease.

SARS-CoV-2 has caused a global pandemic of COVID-19, posing a huge threat to public health. The SARS-CoV-2 papain-like cysteine protease (PLpro) plays a significant role in virus replication and host immune regulation, which is a promising antiviral drug target. Several potential inhibitors have been identified in vitro. However, the detailed mechanism of action and structure-activity relationship require further studies. Here, we investigated the structure-activity relationships of the series of derivatives of tanshinone IIA sulfonate sodium (TSS) and chloroxine based on biochemical analysis and molecular dynamics simulation. We found that compound 7, a derivative of chloroxine, can disrupt PLpro-ISG15 interaction and exhibits an antiviral effect for SARS-CoV-2 variants (wild type, delta, and omicron) at the low micromolar level. These studies confirmed that inhibiting PLpro-ISG15 interaction and, thus, restoring the host's innate immunity are effective methods for fighting against viral infection.

Repurposing clinically approved drugs for COVID-19 treatment targeting SARS-CoV-2 papain-like protease.

COVID-19 is a disease caused by SARS-CoV-2, which has led to more than 4 million deaths worldwide. As a result, there is a worldwide effort to develop specific drugs for targeting COVID-19. Papain-like protease (PLpro) is an attractive drug target because it has multiple essential functions involved in processing viral proteins, including viral genome replication and removal of post-translational ubiquitination modifications. Here, we established two assays for screening PLpro inhibitors according to protease and anti-ISGylation activities, respectively. Application of the two screening techniques to the library of clinically approved drugs led to the discovery of tanshinone IIA sulfonate sodium and chloroxine with their IC50 values of lower than 10 µM. These two compounds were found to directly interact with PLpro and their molecular mechanisms of binding were illustrated by docking and molecular dynamics simulations. The results highlight the usefulness of the two developed screening techniques for locating PLpro inhibitors.

Study on the effects of Zhuanggu Guanjie Pill, a modern Chinese medicine formula, on the activities and mRNA expression of seven CYP isozymes in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Zhuanggu Guanjie Pill (ZGGJP), a modern Chinese medicine formula, is composed of 12 herbs and has been used to treat osteoporosis in China for almost 30 years. However, no in vivo study of the influences of ZGGJP on the cytochrome P450 (CYP) activities have been reported. AIM OF THE STUDY: The aim of this study was to evaluate the effects of ZGGJP on the activities and the mRNA expression of CYP enzymes (CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A) and their corresponding nuclear receptor levels in rats. MATERIALS AND METHODS: After 7 days oral treatment of ZGGJP at low- and high-dose, cocktail solution was given to rats. Blood samples were collected at series of time points. The plasma concentrations of probe drugs and their corresponding metabolites were determined by UPLC-MS/MS. The influence of ZGGJP on the activities of seven CYPs were evaluated the metabolic ratios (Cmax and AUC0-t) for metabolites/probe drugs. In addition, the effects of ZGGJP on the mRNA expression of CYPs and their corresponding nuclear receptors in rat liver were evaluated by real-time PCR. RESULTS: ZGGJP showed significant inductive effects on CYP1A2 and CYP2B6 of both male and female rats. The influence of ZGGJP on CYP2C9 and CYP3A showed gender difference. ZGGJP could induce the activities of CYP2C9 and CYP3A in female rats, but have no influence on the activities in male rats. ZGGJP had no effects on CYP2D6, CYP2C19 and CYP2E1. The mRNA expression results of CYPs were in accordance with the pharmacokinetic results. The mRNA expression levels of constitutive androstane receptor (CAR) and vitamin D receptor (VDR) were increased significantly in female rats at high dosage, but no significant changes were observed in male rats. CONCLUSION: ZGGJP had inductive effects on CYP1A2 and CYP2B6 in both male and female rats. The results showed that ZGGJP could induce the activities of CYP2C9 and CYP3A in female rats, but had no effect in male rats. This may suggest that the influence of ZGGJP on CYP2C9 and CYP3A exhibit gender difference. The inductive effects of ZGGJP on the activities of CYPs, exhibiting gender difference, may be regulated by CAR and VDR. Therefore, co-administration of ZGGJP with other drugs, especially using CYP2C9 and CYP3A substrates in females, may need dose adjustment to avoid herb-drug interaction.

Drug Repurposing of Itraconazole and Estradiol Benzoate against COVID-19 by Blocking SARS-CoV-2 Spike Protein-Mediated Membrane Fusion.

SARS-CoV-2 caused the emerging epidemic of coronavirus disease in 2019 (COVID-19). To date, there are more than 82.9 million confirmed cases worldwide, there is no clinically effective drug against SARS-CoV-2 infection. The conserved properties of the membrane fusion domain of the spike (S) protein across SARS-CoV-2 make it a promising target to develop pan-CoV therapeutics. Herein, two clinically approved drugs, Itraconazole (ITZ) and Estradiol benzoate (EB), are found to inhibit viral entry by targeting the six-helix (6-HB) fusion core of SARS-CoV-2 S protein. Further studies shed light on the mechanism that ITZ and EB can interact with the heptad repeat 1 (HR1) region of the spike protein, to present anti-SARS-CoV-2 infections in vitro, indicating they are novel potential therapeutic remedies for COVID-19 treatment. Furthermore, ITZ shows broad-spectrum activity targeting 6-HB in the S2 subunit of SARS-CoV and MERS-CoV S protein, inspiring that ITZ have the potential for development as a pan-coronavirus fusion inhibitor.

Preparation and characterization of a Schiff-based chitosan-fructose quaternary ammonium salt for medical applications.

The aim of this study was to develop a new chitosan derivative and investigate its effects on fresh tissue healing in rats. A chitosan-fructose Schiff based quaternary ammonium salt (CS = Fru-DEAE) was synthesized for the first time and characterized using FT-IR and 1HNMR, and the modification rate and the solution properties were studied. A rat wound model was established, and the experimental group was treated using 0.1 g of the chitosan derivative hydrogel. The wound healing rate, and the concentration of collagen III and proline in the wounds were assessed in the experimental group and compared with those of the control group at 7, 10, and 15 d. The CS = Fru-DEAE hydrogel demonstrated good performance and promoted the healing of infected wounds in rats. The hydrogel could accelerate the infiltration of inflammatory cells and increase the amount of type III collagen in the wound area, which likely contributed to its efficacy.

Interface engineering of microelectrodes toward ultrasensitive monitoring of ß-amyloid peptides in cerebrospinal fluid in Alzheimer's disease.

Ultrasensitive detection of monomeric ß-amyloid peptides is of fundamental significance for studying the pathological progression of Alzheimer's disease (AD). In this article, by facilely engineering a gold microelectrode interface, we developed a novel electrochemical biosensor for sensitive and selective monitoring of ß-amyloid peptide (Aß) monomers in cerebrospinal fluid (CSF). Through specific Cu2+-Aß-hemin coordination, Aß directed the assembly of Cu2+-PEI/AuNPs-hemin nanoprobes into network aggregates on a microelectrode interface, which promoted the enrichment of Aß monomers on the microelectrode. Furthermore, the AuNP aggregate promotes the deposition of silver nanoparticles, which were utilized for the electrochemical stripping analysis of the Aß monomer. The proposed method displayed ultra-sensitivity for Aß monomers with the detection limit down to 0.2 pM. Besides, high selectivity toward Aß monomers was observed. These remarkable analytical performances render the electrochemical biosensor useful for evaluating the dynamic change of Aß monomer level in CSF of live mice with AD, promoting the investigation of the role that Aß monomers play in brain events.

Amelioration of type 1 diabetes by recombinant fructose-1,6-bisphosphate aldolase and cystatin derived from Schistosoma japonicum in a murine model.

Infection with helminth parasites or the administration of their antigens can prevent or attenuate autoimmune diseases. To date, the specific molecules that prime the amelioration are only limited. In this study, recombinant Schistosoma japonicum cystatin (rSjcystatin) and fructose-1,6-bisphosphate aldolase (rSjFBPA) were administered to female NOD mice via intraperitoneal (i.p.) injection to characterize the immunological response by the recombinant proteins. We have shown that the administration of rSjcystatin or rSjFBPA significantly reduced the diabetes incidence and ameliorated the severity of type 1 diabetes mellitus (T1DM). Disease attenuation was associated with suppressed interferon-gamma (IFN-γ) production in autoreactive T cells and with a switch to the production of Th2 cytokines. Following rSjcystatin or rSjFBPA injection, regulatory T cells (Tregs) were remarkably increased, which was accompanied by increased expression of interleukin-10 (IL-10) and transforming growth factor beta (TGF-ß). Our study suggests that helminth-derived proteins may be useful in strategies to limit pathology by promoting the Th2 response and upregulating Tregs during the inflammatory tissue-damage process in T1DM.

Enantiomers of Single Chirality Nanotube as Chiral Recognition Interface for Enhanced Electrochemical Chiral Analysis.

Although separation of single-walled carbon nanotubes (SWCNTs) according to their helicity and handedness has been attracting tremendous interest recently, exploration of the left- and right-handed SWCNT enantiomers (defined as "M" and "P") to chiral sensing still remains in the early stage. Here we presented a new electrochemical sensor for chiral discrimination, which for the first time amplified the chiral selection on the electrode surface based on the left- or right-handed semiconducting SWCNT enantiomers with (6,5)-enriched chirality. The enantioselectivity was demonstrated by different peak current response to analyte enantiomers, observed in differential pulse voltammogram (DPV). Chiral distinguishing might be a result of the formation of an efficient chiral nanospace originating from the high purity of single enantiomer of (6,5) SWCNT. The obtained chiral electrodes were also applied to determine the enantiomeric excess (ee) of DOPA. There was a good linear relationship between DPV peak currents and % ee of l-DOPA. This study is the first example showing how the structure of chiral SWCNTs influences electrochemical chiral recognition.

[Recombinant expression of Schistosoma japonicum fructose-1, 6-bisphos- phate aldolase and its expression in different developmental stages of S. japonicum].

OBJECTIVE: To clone, express and purify Schistosoma japonicum fructose-1, 6-bisphosphate aldolase (SjFBPA) in E. coli and observe its expression in different developmental stages of S. japonicum. METHODS: FBPA gene was amplified from S. japonicum adult worm cDNA by using PCR. The amplified product was recombined into pET28a plasmid, and inducibly expressed with IPTG in E. coli BL21. SDS-PAGE and Western blotting were employed to analyze and identify the recombinant protein SjFBPA (rSjFBPA). Then, rSjFBPA was purified by chromatographic purification and its purity was analyzed by SDS- PAGE. The protein concentration of rSjFBPA purified was measured by the BCA method. Furthermore, SjFBPA mRNA was ana- lyzed in different developmental stages of S. japonicum by RT-PCR. RESULTS: SjFBPA was successfully amplified by using PCR and identified by restriction enzyme digestion and sequencing. The Western blotting analysis confirmed that the recombinant pro- tein could specifically reactive to the anti-His-tag monoclonal antibody. The concentration of the purified recombinant protein was about 4 mg/ml. The result of RT-PCR showed that SjFBPA mRNA was expressed in cercaria, schistosomulum, adult worm and egg of S. japonicum. CONCLUSION: SjFBPA is successfully recombined and expressed in a prokaryotic system, and SjFBPA mRNA is expressed in cercaria, schistosomulum, adult worm and egg of S. japonicum.

[Association of murine double minute 2 and P53 polymorphisms with breast cancer susceptibility].

OBJECTIVE: To investigate the combined effects between the two polymorphisms murine double minute 2 (MDM2) rs2279744 T→G and P53 rs1042522 G→C on the genetic susceptibility of breast cancer. METHODS: A total of 600 female patients with diagnosed breast cancer were consecutively recruited from the Yuhang district, Hangzhou city during March 2001 to May 2009. In the same period as the cases were collected, 600 healthy women living in Yuhang district, Hangzhou city were selected from a nutritional survey conducted. Peripheral blood lymphocytes were obtained from the study subjects and the demographic information were collected through questionnaires. PCR-restriction fragment length polymorphism (PCR-RFLP) was used for genotyping MDM2 rs2279744 T→G and P53 rs1042522 G→C. Logistic regression analysis was used to analyze the combined effects of the two polymorphisms on breast cancer risk. RESULTS: The frequency of MDM2 rs2279744 GG, TG and TT genotypes were 31.5% (189/600), 45.5% (273/600), 23.0% (138/600) in case group and 19.0% (114/600), 49.2% (295/600), 31.8% (191/600) in control group. The frequency of P53 rs1042522 GG, GC and CC genotypes were 23.1% (139/600), 50.2% (301/600), 26.7% (160/600) in case group and 30.5% (183/600), 51.3% (308/600), 18.2% (109/600) in control group. Logistic regression analysis showed that carriers with rs2279744 TG, GG genotypes had a significant increased risk for developing breast cancer compared with rs2279744 TT carriers (OR = 1.31, 95%CI: 0.97 - 1.73 for TG; OR = 2.24, 95%CI: 1.61 - 3.09 for GG). When comparing with rs1042522 GG carriers, carriers with rs1042522 GC, CC genotypes had a significant increased risk for developing breast cancer (OR = 1.34, 95%CI: 0.94 - 1.68 for GC; OR = 1.89, 95%CI: 1.35 - 2.68 for CC). The united analysis of this two polymorphisms showed that compared with individuals carrying rs2279744 TT and rs1042522 GG (the frequency were 4.8% (29/600) in case group and 11.5% (69/600) in control group), carries with rs2279744 TG/GG and rs1042522 GC/GG genotypes (the frequency were 95.2% (571/600) in case group and 88.5% (531/600) in control group) showed significant higher risk in the susceptibility to breast cancer (OR = 2.30, 95%CI: 1.39 - 3.82 for TG/GC + GG; OR = 2.14, 95%CI: 1.29 - 3.55 for TT + GC/CC; OR = 2.86, 95%CI: 1.80 - 4.53 for TG/GG + GC/CC). The combination of MDM2 rs2279744 T→G and P53 rs1042522 G→C contributed to a significantly higher risk of breast cancer than did any one of the variant (P = 0.046). The risk of susceptibility to breast cancer was much higher when this two polymorphisms both variant. CONCLUSIONS: The MDM2 rs2279744 T→G and P53 rs1042522 G→C may be risk factor for breast cancer. Significant combined effects between the two polymorphisms may contribute to the genetic susceptibility to breast cancer.