Enhancing therapeutic efficacy in luminal androgen receptor triple-negative breast cancer: exploring chidamide and enzalutamide as a promising combination strategy.

Extensive exploration of the molecular subtypes of triple-negative breast cancer (TNBC) is critical for advancing precision medicine. Notably, the luminal androgen receptor (LAR) subtype has attracted attention for targeted treatment combining androgen receptor antagonists and CDK4/6 inhibitors. Unfortunately, this strategy has proven to be of limited efficacy, highlighting the need for further optimization. Using our center's comprehensive multiomics dataset (n = 465), we identified novel therapeutic targets and evaluated their efficacy through multiple models, including in vitro LAR cell lines, in vivo cell-derived allograft models and ex vivo patient-derived organoids. Moreover, we conducted flow cytometry and RNA-seq analysis to unveil potential mechanisms underlying the regulation of tumor progression by these therapeutic strategies. LAR breast cancer cells exhibited sensitivity to chidamide and enzalutamide individually, with a drug combination assay revealing their synergistic effect. Crucially, this synergistic effect was verified through in vivo allograft models and patient-derived organoids. Furthermore, transcriptomic analysis demonstrated that the combination therapeutic strategy could inhibit tumor progression by regulating metabolism and autophagy. This study confirmed that the combination of histone deacetylase (HDAC) inhibitors and androgen receptor (AR) antagonists possessed greater therapeutic efficacy than monotherapy in LAR TNBC. This finding significantly bolsters the theoretical basis for the clinical translation of this combination therapy and provides an innovative strategy for the targeted treatment of LAR TNBC.

Kinetics of Nanobubbles in Tiny-Angle Twisted Bilayer Graphene.

Realization of high-quality van der Waals (vdWs) heterostructures by stacking two-dimensional (2D) layers requires atomically clean interfaces. Because of strong adhesion between the constituent layers, the vdWs forces could drive trapped contaminants together into submicron-size "bubbles", which leaves large interfacial areas atomically clean. Here, we study the kinetics of nanobubbles in tiny-angle twisted bilayer graphene (TBG) and our results reveal a substantial influence of the moiré superlattice on the motion of nanoscale interfacial substances. Our experiments indicate that the bubbles will mainly move along the triangular network of domain boundaries in the tiny-angle TBG when the sizes of the bubbles are comparable to that of an AA-stacking region. When the size of the bubble is smaller than that of an AA-stacking region, the bubble becomes motionless and is fixed in the AA-stacking region, because of its large out-of-plane corrugation.

Wnt/ß-catenin signalling pathway in breast cancer cells and its effect on reversing tumour drug resistance by alkaloids extracted from traditional Chinese medicine.

Breast cancer is a high-risk disease with a high mortality rate among women. Chemotherapy plays an important role in the treatment of breast cancer. However, chemotherapy eventually results in tumours that are resistant to drugs. In recent years, many studies have revealed that the activation of Wnt/ß-catenin signalling is crucial for the emergence and growth of breast tumours as well as the development of drug resistance. Additionally, drugs that target this pathway can reverse drug resistance in breast cancer therapy. Traditional Chinese medicine has the properties of multi-target and tenderness. Therefore, integrating traditional Chinese medicine and modern medicine into chemotherapy provides a new strategy for reversing the drug resistance of breast tumours. This paper mainly reviews the possible mechanism of Wnt/ß-catenin in promoting the process of breast tumour drug resistance, and the progress of alkaloids extracted from traditional Chinese medicine in the targeting of this pathway in order to reverse the drug resistance of breast cancer.

Tunable Sample-Wide Electronic Kagome Lattice in Low-Angle Twisted Bilayer Graphene.

Overlaying two graphene layers with a small twist angle θ can create a moiré superlattice to realize exotic phenomena that are entirely absent in a graphene monolayer. A representative example is the predicted formation of localized pseudo-Landau levels (PLLs) with kagome lattice in tiny-angle twisted bilayer graphene (TBG) with θ<0.3° when the graphene layers are subjected to different electrostatic potentials. However, this was shown only for the model of rigidly rotated TBG, which is not realized in reality due to an interfacial structural reconstruction. It is believed that the interfacial structural reconstruction strongly inhibits the formation of the PLLs. Here, we systematically study electronic properties of the TBG with 0.075°≤θ<1.2° and demonstrate, unexpectedly, that the PLLs are quite robust for all the studied TBG. The structural reconstruction suppresses the formation of the emergent kagome lattice in the tiny-angle TBG. However, for the TBG around the magic angle, the sample-wide electronic kagome lattices with tunable lattice constants are directly imaged by using a scanning tunneling microscope. Our observations open a new direction to explore exotic correlated phases in moiré systems.

Oscillations of the Spacing between van Hove Singularities Induced by sub-Ångstrom Fluctuations of Interlayer Spacing in Graphene Superlattices.

Physical properties of two-dimensional van der Waals (vdWs) structures depend sensitively on both stacking orders and interlayer interactions. Yet, in most cases studied to date, the interlayer interaction is considered to be a "static" property of the vdWs structures. Here we demonstrate that applying a scanning tunneling microscopy (STM) tip pulse on twisted bilayer graphene (TBG) can induce sub-Ångstrom fluctuations of the interlayer separation in the TBG, which are equivalent to dynamic vertical external pressure of about 10 GPa on the TBG. The sub-Ångstrom fluctuations of the interlayer separation result in large oscillations of the energy separations between two van Hove singularities (VHSs) in the TBG. The period of the oscillations of the VHSs spacing is extremely long, about 500-1000 sec, attributing to tip-induced local stress in the atomic-thick TBG. Our result provides an efficient method to tune and measure the physical properties of the vdWs structures dynamically.

Stimulation of histamine H4 receptor participates in cold-induced browning of subcutaneous white adipose tissue.

Although many studies have shown that histamine and its signaling regulate energy homeostasis through the central nervous system, their roles in adipose tissues remain poorly understood. Here, we identified that the histamine H4 receptor (HrH4) was highly expressed in adipocytes at a level higher than that of the other three receptors (i.e., HrH1, HrH2, and HrH3). The HrH4 expression in adipocytes responded to cold through thermogenesis and lipolysis, supported by results from both mouse and cell models. When HrH4 expression was knocked down in the subcutaneous white adipose tissue (scWAT), browning and lipolysis effects triggered by cold were ablated, and the oxygen consumption was also lowered both at the normal and cold conditions. Moreover, mice exhibited browned scWAT, accelerated metabolic rates, and tolerance to hypothermia when 4-methylhistamine (4MH), a selective HrH4 agonist, was adjacently injected to the scWAT. Consistent with these findings, 4MH also triggered the browning and lipolytic effects in cultured C3H10T1/2 adipocytes. Mechanically, we demonstrated that p38/MAPK and ERK/MAPK pathways were involved in these processes. In conclusion, our findings have uncovered an effective role of HrH4 in adipose tissue browning.

Pharmacokinetics, bioavailability and metabolism of scopoletin in dog by ultra-high-performance liquid chromatography combined with linear ion trap-Orbitrap tandem mass spectrometry.

A highly sensitive and selective method based on ultra-high-performance liquid chromatography combined with linear ion trap-Orbitrap tandem mass spectrometry (UHPLC-LTQ-Orbitrap-MS) has been developed and validated for the determination of scopoletin in dog plasma. The analyte was extracted from plasma samples using acetonitrile and separated on an Acquity UPLC BEH C18 column (50 × 2.1 mm, 1.7 µm) with 0.05% ammonium hydroxide and acetonitrile as mobile phase. The developed method was linear over the concentration range of 1-500 ng/mL, with a correlation coefficient >0.9988. The intra- and inter-day precisions (RSD) were <8.93% while the accuracy (RE) ranged from -6.50 to 8.12%. Extraction recovery, matrix effect and stability for dog plasma samples were within the required limits. The validated method has been successfully applied to investigate the pharmacokinetics and metabolism of scopoletin in dog plasma after intravenous (1 mg/kg) and oral (10, 25, 50 mg/kg) administration. The results revealed that (a) scopoletin showed short elimination half-life in dog; (b) its oral bioavailability was low (within the range of 5.69-7.08%); (c) scopoletin showed dose-independent pharmacokinetic profiles in dog plasma over the dose range of 10-50 mg/kg; and (d) glucuronidation was the predominant metabolic pathway in dog.

Basilic vein variation encountered during surgery for arm vein port: A case report.

BACKGROUND: Venous variations are uncommon and usually hard to identify, and basilic vein variation is particularly rare. Basilic vein variation usually presents without any clinical symptoms and is often regarded as a benign alteration. This case was a patient with congenital basilic vein variation encountered during surgery for an infusion port. CASE SUMMARY: We documented and analyzed an uncommon anatomical variation in the basilic vein encountered during arm port insertion. This peculiarity has hitherto remained undescribed in the literature. We offer remedial strategies for addressing this anomaly in the future and precautionary measures to circumvent its occurrence. We conducted a comprehensive review of analogous cases in the literature, offering pertinent therapeutic recommendations and solutions, with the aim of enhancing the efficacy and safety of future arm port implantations. CONCLUSION: Venous variation is rare and requires detailed intraoperative and postoperative examination to ensure accuracy, so as not to affect subsequent treatment.

Robust flat bands in twisted trilayer graphene moiré quasicrystals.

Moiré structures formed by twisting three layers of graphene with two independent twist angles present an ideal platform for studying correlated quantum phenomena, as an infinite set of angle pairs is predicted to exhibit flat bands. Moreover, the two mutually incommensurate moiré patterns among the twisted trilayer graphene (TTG) can form highly tunable moiré quasicrystals. This enables us to extend correlated physics in periodic moiré crystals to quasiperiodic systems. However, direct local characterization of the structure of the moiré quasicrystals and of the resulting flat bands are still lacking, which is crucial to fundamental understanding and control of the correlated moiré physics. Here, we demonstrate the existence of flat bands in a series of TTGs with various twist angle pairs and show that the TTGs with different magic angle pairs are strikingly dissimilar in their atomic and electronic structures. The lattice relaxation and the interference between moiré patterns are highly dependent on the twist angles. Our direct spatial mappings, supported by theoretical calculations, reveal that the localization of the flat bands exhibits distinct symmetries in different regions of the moiré quasicrystals.

Age-based factors modulating the required thyroxine dose to achieve thyrotropin suppression in intermediate-and high-risk papillary thyroid cancer.

Background: Guidelines widely recommend thyrotropin suppression to reduce the risk of recurrence in intermediate- and high-risk papillary thyroid cancer (PTC) after total thyroidectomy. However, an insufficient or excessive dosage may result in a number of symptoms/complications especially in older patients. Patients and methods: We constructed a retrospective cohort including 551 PTC patient encounters. Using propensity score matching and logistic regression models, we determined the independent risk factors affecting levothyroxine therapy at different ages. Our outcomes included: expected TSH level and an unexpected TSH level, which was based on the initial thyroid-stimulating hormone (TSH) goal< 0.1 mIU/L with usual dosage of L-T4 (1.6 µg/kg/day). Results: From our analysis, more than 70% of patients undergoing total thyroidectomy did not achieve the expected TSH level using an empirical medication regimen, and the effect of the drug was affected by age (odds ratio [OR], 1.063; 95% CI, 1.032-1.094), preoperative TSH level (OR, 0.554; 95% CI, 0.436-0.704) and preoperative fT3 level (OR, 0.820; 95% CI, 0.727-0.925). In patients with age < 55 years old, preoperative TSH level (OR, 0.588; 95% CI, 0.459-0.753), and preoperative fT3 level (OR, 0.859; 95% CI, 0.746-0.990) were two independent protective factors, while, in patients with age ≥ 55 years old, only preoperative TSH level (OR, 0.490; 95% CI, 0.278-0.861) was the independent protective factors to achieve expected TSH level. Conclusion: Our retrospective analysis suggested the following significant risk factors of getting TSH suppression in PTC patients: age (≥55 years), lower preoperative TSH and fT3 levels.

Molecular features and clinical implications of the heterogeneity in Chinese patients with HER2-low breast cancer.

The molecular heterogeneity and distinct features of HER2-low breast cancers, particularly in the Chinese population, are not well understood, limiting its precise management in the era of antibody‒drug conjugates. To address this issue, we established a cohort of 434 Chinese patients with HER2-low breast cancer (433 female and one male) and integrated genomic, transcriptomic, proteomic, and metabolomic profiling data. In this cohort, HER2-low tumors are more distinguished from HER2-0 tumors in the hormone receptor-negative subgroup. Within HER2-low tumors, significant interpatient heterogeneity also exists in the hormone receptor-negative subgroup: basal-like tumors resemble HER2-0 disease, and non-basal-like HER2-low tumors mimic HER2-positive disease. These non-basal-like HER2-low tumors are enriched in the HER2-enriched subtype and the luminal androgen receptor subtype and feature PIK3CA mutation, FGFR4/PTK6/ERBB4 overexpression and lipid metabolism activation. Among hormone receptor-positive tumors, HER2-low tumors show less loss/deletion in 17q peaks than HER2-0 tumors. In this work, we reveal the heterogeneity of HER2-low breast cancers and emphasize the need for more precise stratification regarding hormone receptor status and molecular subtype.

Comprehensive analysis of the effect of Hashimoto's thyroiditis on the diagnostic efficacy of preoperative ultrasonography on cervical lymph node lesions in papillary thyroid cancer.

Purpose: Hashimoto's thyroiditis often leads to reactive hyperplasia of the central compartment lymph nodes in papillary thyroid carcinoma (PTC) patients. However, the effect and clinical significance of Hashimoto's thyroiditis (HT) on ultrasonography evaluation for cervical lymph node (LN) lesions remain unknown. This study aims to investigate the effect of Hashimoto's thyroiditis on the diagnostic efficacy of preoperative ultrasonography on cervical lymph node lesions in PTC patients. Patients and methods: This study consecutively enrolled 1,874 PTC patients who underwent total thyroidectomy and radical cervical lymph node dissection between January 2010 and December 2021. Eligible patients were categorized as with HT and without HT. The diagnostic performance of preoperative ultrasonography for cervical LN lesions (including central LNs and lateral LNs) was evaluated between PTC patients with HT and those without HT, respectively. Results: Among the 1,874 PTC patients, 790 (42.1%) had central cN+ and 1,610 (85.9%) had lateral cN+. Compared with PTC patients without HT, the preoperative US for central LNs displays a higher false-positive rate (27.9% vs. 12.2%, p <0.001) and a lower specificity (72.1% vs. 87.8%, p < 0.001) in PTC patients with HT. Moreover, in PTC patients with HT, the ratio of the absence of fatty hilum in central LNs without metastasis was higher than in PTC patients without HT (13.02% vs. 7.46%, p = 0.013). However, no such differences were observed in lateral LNs. Conclusion: HT will interfere with the preoperative US evaluation for central LNs and increase the incidence of the absence of fatty hilum in central benign LNs. When PTC patients have concomitant HT, clinicians should thoroughly evaluate the central LNs, thereby decreasing the incidence of misdiagnosis and unnecessary surgery.

Comprehensive Analysis of Prognostic Alternative Splicing Signature Reveals Recurrence Predictor for Papillary Thyroid Cancer.

BACKGROUND: Alternative splicing (AS) plays a key role in the diversity of proteins and is closely associated with tumorigenicity. The aim of this study was to systemically analyze RNA alternative splicing (AS) and identify its prognostic value for papillary thyroid cancer (PTC). METHODS: AS percent-splice-in (PSI) data of 430 patients with PTC were downloaded from the TCGA SpliceSeq database. We successfully identified recurrence-free survival (RFS)-associated AS events through univariate Cox regression, LASSO regression and multivariate regression and then constructed different types of prognostic prediction models. Gene function enrichment analysis revealed the relevant signaling pathways involved in RFS-related AS events. Simultaneously, a regulatory network diagram of AS and splicing factors (SFs) was established. RESULTS: We identified 1397 RFS-related AS events which could be used as the potential prognostic biomarkers for PTC. Based on these RFS-related AS events, we constructed a ten-AS event prognostic prediction signature that could distinguish high-and low-risk patients and was highly capable of predicting PTC patient prognosis. ROC curve analysis revealed the excellent predictive ability of the ten-AS events model, with an area under the curve (AUC) value of 0.889; the highest prediction intensity for one-year RFS was 0.923, indicating that the model could be used as a prognostic biomarker for PTC. In addition, the nomogram constructed by the risk score of the ten-AS model also showed high predictive efficiency for the prognosis of PTC patients. Finally, the constructed SF-AS network diagram revealed the regulatory role of SFs in PTC. CONCLUSION: Through the limited analysis, AS events could be regarded as reliable prognostic biomarkers for PTC. The splicing correlation network also provided new insight into the potential molecular mechanisms of PTC.

Effects of marital status on survival of medullary thyroid cancer stratified by age.

PURPOSE: Marital status has emerged as an important influence on several cancer outcomes, but its role in medullary thyroid cancer (MTC) remains unclear. This study was to explore the effects of marital status on the prognosis of MTC patients and to determine whether its effects vary by age. PATIENTS AND METHODS: We retrospectively extracted 1344 eligible patients diagnosed with MTC between 2004 and 2015 from the Surveillance, Epidemiology, and End Results (SEER) database. Based on the marital status, we divided those patients into married and unmarried groups. We compared the difference in overall survival (OS) and cancer-specific survival (CSS) between married and unmarried via the Kaplan-Meier analysis. Univariate and multivariate Cox proportional models were performed to identify the prognostic factors of OS and CSS. RESULTS: There were 1344 MTC eligible patients in a total of which 883 (65.7%) were married and 461 (34.3%) were unmarried. The comparison observed between married and unmarried patients was as follows: male (45.2% vs. 28.0%), age (≥52 years) (55.9% vs. 44.6%), White (86.7% vs. 78.7%), and undergo surgery (97.7% vs. 93.3%). Multivariate analysis revealed unmarried status as a risk factor independently associated with worse OS (HR: 2.15, 95% CI: 1.59-2.92) rate and CSS (HR: 1.70, 95% CI: 1.17-2.47) rate. In a further analysis stratified by age, there was no significant difference in OS and CSS between married and unmarried patients younger than 52 years. For the remaining group with 52 years old and higher, unmarried patients showed significantly higher risk of OS and CSS than married patients at all stages of the pathology except M1 stage. CONCLUSION: Married patients with MTC have a better prognosis than unmarried ones. Age can affect the association between marital status and the survival of MTC, and married elders may benefit more than youngers.

In situ forming hydrogel of natural polysaccharides through Schiff base reaction for soft tissue adhesive and hemostasis.

In this study, a novel injectable hydrogel with biocompatibility and biodegradability through Schiff base reaction was prepared for soft tissue adhesive and hemostasis. Aldehyde hydroxyethyl starch (AHES) was prepared by oxidizing hydroxyethyl starch to get aldehyde groups. Amino carboxymethyl chitosan (ACC) was prepared by grafting ethylenediamine onto carboxymethyl chitosan to get more amino groups. Two-component AHES/ACC hydrogel was formed through Schiff base reaction between aldehyde and amino groups. By changing the reaction conditions various contents of aldehyde and amino group were achieved. The properties of AHES/ACC hydrogel were tunable including gelation time, swelling ratio, degradation and mechanical tensile by varying the content of aldehyde and amino groups. Then biocompatibility measurements showed that AHES/ACC hydrogels supported cell viability and proliferation in vitro and exhibited good biodegradability and biocompatibility in vivo. AHES/ACC hydrogel also had effective hemostatic ability. Thus, this study provides a strategy for the design and fabrication of fast in situ forming hydrogels. Through Schiff base reaction in situ forming hydrogel derived from natural polysaccharides can be modulated and prepared for soft tissue adhesive, hemostasis or other biomedical applications in future.

A Nomogram Predicting Lymph Node Metastasis in T1 Breast Cancer based on the Surveillance, Epidemiology, and End Results Program.

Background: Patients with early stage breast cancer with lymph nodes metastasis were proven to have more aggressive biologically phenotypes. This study aimed to build a nomogram to predict lymph node metastasis in patients with T1 breast cancer. Methods: We identified female patients with T1 breast cancer diagnosed between 2010 and 2014 in the Surveillance, Epidemiology and End Results database. The patients were randomized into training and validation sets. Univariate and multivariate logistic regressions were carried out to assess the relationships between lymph node metastasis and clinicopathological characteristics. A nomogram was developed and validated by a calibration curve and receptor operating characteristic curve analysis. Result: Age, race, tumour size, tumour primary site, pathological grade, oestrogen receptor (ER) status, progesterone receptor (PR) status and human epidermal growth factor receptor 2 (HER2) status were independent predictive factors of positive lymph node metastasis in T1 breast cancer. Increasing age, tumour size and pathological grade were positively correlated with the risk of lymph node metastasis. We developed a nomogram to predict lymph node metastasis and further validated it in a validation set, with areas under the receiver operating characteristic curves of 0.733 and 0.741 in the training and validation sets, respectively. Conclusions: A better understanding of the clinicopathological characteristics of T1 breast cancer patients might important for assessing their lymph node status. The nomogram developed here, if further validated in other large cohorts, might provide additional information regarding lymph node metastasis. Together with sentinel lymph node biopsy, this nomogram can help comprehensively predict lymph node metastasis.

BMP4 facilitates beige fat biogenesis via regulating adipose tissue macrophages.

Thermogenic beige fat improves metabolism and prevents obesity. Emerging evidence shows that the activation of M2 macrophages stimulates beige adipogenesis, whereas the activation of M1 macrophages, which play a major role in inflammation, impedes beige adipogenesis. Thus, the identification of factors that regulate adipose tissue macrophages (ATMs) will help clarify the mechanism involved in beiging. Here, we found that one of the secreted proteins in adipose tissue, namely, BMP4, alters the ATM profile in subcutaneous adipose tissue by activating M2 and inhibiting M1 macrophages. Mechanistically, the BMP4-stimulated p38/MAPK/STAT6/PI3K-AKT signalling pathway is involved. Meanwhile, BMP4 improved the potency of M2 macrophages to induce beige fat biogenesis. Considering that the overexpression of BMP4 in adipose tissue promotes the beiging of subcutaneous adipose tissue and improves insulin sensitivity, these findings provide evidence that BMP4 acts as an activator of beige fat by targeting immuno-metabolic pathways.

Genomic and Transcriptomic Landscape of Triple-Negative Breast Cancers: Subtypes and Treatment Strategies.

We comprehensively analyzed clinical, genomic, and transcriptomic data of a cohort of 465 primary triple-negative breast cancer (TNBC). PIK3CA mutations and copy-number gains of chromosome 22q11 were more frequent in our Chinese cohort than in The Cancer Genome Atlas. We classified TNBCs into four transcriptome-based subtypes: (1) luminal androgen receptor (LAR), (2) immunomodulatory, (3) basal-like immune-suppressed, and (4) mesenchymal-like. Putative therapeutic targets or biomarkers were identified among each subtype. Importantly, the LAR subtype showed more ERBB2 somatic mutations, infrequent mutational signature 3 and frequent CDKN2A loss. The comprehensive profile of TNBCs provided here will serve as a reference to further advance the understanding and precision treatment of TNBC.

Long non-coding RNA-ENST00000434223 suppresses tumor progression in gastric cancer cells through the Wnt/ß-catenin signaling pathway.

BACKGROUND: Gastric cancer (GC) develops from the lining of the stomach. The present study aimed to explore the effects of long non-coding RNA-ENST00000434223 (lncRNA ENST00000434223) on gastric cancer (GC) cells. METHODS: One hundred and four GC tissues and paracancerous tissues were collected from GC patients, and expression of ENST00000434223, Wnt2b, ß-catenin, cyclinD1, E-cadherin, N-cadherin, vimentin, and snail was subsequently assessed. Morphological changes in cells were assessed using an inverted microscope, and expression of Bcl-2, Bax and caspase-3 was examined. RESULTS: We found that expression of Wnt2b, ß-catenin, cyclinD1, N-cadherin, vimentin, and snail was increased in GC tissues, while expression of ENST00000434223 and E-cadherin was decreased. SGC-7901 cells were closely arranged, and expression of Wnt2b, ß-catenin, CyclinD1, N-cadherin, Vimentin, snail and Bcl-2 was increased, whereas expression of ENST00000434223, E-cadherin, Bax and caspase-3 was decreased. Furthermore, the rate of apoptosis was decreased and cell proliferation, invasion and migration were increased in response to downregulation of ENST00000434223. By contrast, upregulation of ENST00000434223 exhibited the opposite effects in MKN-45 cells. CONCLUSION: The results of this study provide a promising experimental basis for the treatment of gastric cancer through interventional targeting of lncRNA ENST00000434223.

Expression of soluble programmed death-1 protein in peripheral blood regulatory T cells and its effects on rheumatoid arthritis progression.

The present study aimed to investigate the role of the soluble programmed death­1 (sPD-1) protein, which is released by peripheral blood regulatory T cells (Treg) during the progression of rheumatoid arthritis (RA). From October 2012 to May 2014, 82 RA patients (RA group) and 90 healthy volunteers (healthy controls; HC) were recruited. Cluster of differentiation (CD)4, CD25 and forkhead/winged helix transcription factor p3 (Foxp3) and expression of cytotoxic T lymphocyte associated antigen 4 (CTLA-4) and Foxp3 were detected by flow cytometry. Expression of sPD­1 in Treg was detected by western blot analysis. Immunosuppressive activity of CD4+CD25­ Treg was measured via thiazolyl blue in an MTT assay. ELISA was used to detect interleukin­10 (IL­10), transforming growth factor beta (TGF-ß), interleukin-4 (IL-4), interferon­Î³ (IFN-γ) and nuclear factor of activated T cells (NF­AT). It was observed that in peripheral blood, CD4+CD25-FOXP3+/CD4+ levels were reduced in the RA group (P<0.001), and sPD­1 levels were markedly higher (P<0.001), compared with the HC group. Additionally, it was observed that relative sPD­1 protein expression in the small interfering RNA (siRNA)-sPD-1 treated group was reduced compared with the untreated and scrambled siRNA groups (all P<0.0001). The mean fluorescence intensity of CTLA-4 and Foxp3 decreased markedly upon transfection with siRNA-sPD-1 (P<0.001). Compared with the normal CD4+CD25­ T group, optical density (OD)540 values, IFN-γ/IL-4 concentration ratio and NF­AT activity in siRNA untreated and scramble groups reduced significantly (all P<0.001). OD540 value, IFN-γ/IL-4 concentration ratio and NF­AT activity in the siRNA­sPD­1 group were significantly upregulated (all P<0.001). Therefore, sPD-1 may suppress the level of CD4+CD25­ Tregs in the peripheral blood of RA patients, and may be involved in a variety of immune processes mediated by CD4+CD25­ Tregs.