Activation of estrogen-related receptor: An alternative mechanism of hexafluoropropylene oxide homologs estrogenic effects.

Perfluorooctanoic acid (PFOA) alternatives such as hexafluoropropylene oxide homologs (HFPOs) cause concern due to increased occurrence in the environment as well as potential bioaccumulation and toxicity. HFPOs have been demonstrated to activate the estrogen receptor (ER) pathway. The ER pathway is homologous and connected to the estrogen-related receptor (ERR) pathway, but HFPOs effects on the ERR pathway have not been studied. Hence, we assessed the potential estrogenic effects of HFPOs via ERRγ pathway. In vitro assays revealed that HFPO dimeric, trimeric, and tetrameric acids (HFPO-DA, -TA, and -TeA, respectively), acted as ERRγ agonists, activating the transcription of both human and zebrafish ERRγ at low concentrations, but inhibiting zebrafish ERRγ at high concentrations. We also found that HFPO-TA promoted the human endometrial cancer cells (Ishikawa cells) proliferation via ERRγ/EGF, Cyclin D1 pathway. The HFPO-TA-induced proliferation of Ishikawa cells was inhibited by co-exposure with a specific antagonist of ERRγ, GSK5182. In vivo exposure of female zebrafish to HFPO-TA disturbed sex hormone levels, interfered with the gene expression involved in estrogen synthesis and follicle regulation, and caused histopathological lesions in the ovaries, which were similar to those induced by a known ERRγ agonist GSK4716. Taken together, this study revealed a new mechanism concerning the estrogenic effect of HFPOs via activation of the ERRγ pathway.

A Preprocessing Manifold Learning Strategy Based on t-Distributed Stochastic Neighbor Embedding.

In machine learning and data analysis, dimensionality reduction and high-dimensional data visualization can be accomplished by manifold learning using a t-Distributed Stochastic Neighbor Embedding (t-SNE) algorithm. We significantly improve this manifold learning scheme by introducing a preprocessing strategy for the t-SNE algorithm. In our preprocessing, we exploit Laplacian eigenmaps to reduce the high-dimensional data first, which can aggregate each data cluster and reduce the Kullback-Leibler divergence (KLD) remarkably. Moreover, the k-nearest-neighbor (KNN) algorithm is also involved in our preprocessing to enhance the visualization performance and reduce the computation and space complexity. We compare the performance of our strategy with that of the standard t-SNE on the MNIST dataset. The experiment results show that our strategy exhibits a stronger ability to separate different clusters as well as keep data of the same kind much closer to each other. Moreover, the KLD can be reduced by about 30% at the cost of increasing the complexity in terms of runtime by only 1-2%.

Physiological and transcriptome analyses reveal the response of Ammopiptanthus mongolicus to extreme seasonal temperatures in a cold plateau desert ecosystem.

Ammopiptanthus mongolicus is the only evergreen broad-leaved shrub present in arid areas of Northwest China and plays an important role in maintaining the stability of the local desert ecosystem. It can survive under extreme temperatures (e.g., extreme low temperature: - 24.8 °C and extreme high temperature: 37.7 °C). To understand the gene expression-physiological regulation network of A. mongolicus in extreme temperature environments, we monitored the changes in gene expression and photosynthetic traits of the leaves. The results showed that at low temperatures, the net photosynthetic rates (A), Fv'/Fm' and electron transport rate (ETR) decreased, the Fv/Fm ratio was only 0.32, and the proportion of nonregulatory heat dissipation Y(NO) increased. Based on a KEGG analysis of the differentially expressed genes, 15 significantly enriched KEGG pathways were identified, which were mainly related to circadian rhythm, photosynthesis, lipid metabolism, carbohydrate metabolism, plant hormones and other life activities. At high temperatures, the A value increased, and the proportion of regulatory energy dissipation Y(NPQ) increased. The KEGG analysis identified 24 significantly enriched KEGG pathways, which are mainly related to circadian rhythm, carbon sequestration of photosynthesis, carotenoid biosynthesis, secondary metabolites, cofactors and vitamin metabolism. In general, at the expense of photosynthesis, A. mongolicus can ensure the survival of leaves by increasing Y(NO) levels, regulating the circadian rhythm, increasing the synthesis of unsaturated fatty acids and changing the role of plant hormones. Under high-temperature stress, a high photosynthetic capacity was maintained by adjusting the stomatal conductance (gsw), increasing Y(NPQ), consuming excess light energy, continuously assembling and maintaining PSII, and changing the production of antioxidants.

Antioxidant interventions in autism spectrum disorders: A meta-analysis.

BACKGROUND: Autism spectrum disorder (ASD) might be associated with oxidative stress, and antioxidants are commonly used in the treatment of young people with ASD. However, the evidence about the effectiveness of these interventions remains debatable. We performed a meta-analysis to evaluate the effect of antioxidants on the symptoms of patients with autism. METHODS: Data sources: PubMed and Web of Science databases. STUDY SELECTION: We selected placebo-controlled, double-blind, randomized clinical trials published until February 2021 to evaluate the efficacy of antioxidant interventions on ASD. DATA ANALYSIS: Aberrant Behavior Checklist (ABC), Repetitive Behavior Scale-Revised (RBS), Social Responsiveness Scale (SRS), Developmental Behavior Checklist (DBC) and Clinical Global Impressions Severity scale (CGIS) were used to evaluate the 22 different symptom outcomes. The Hedges-adjusted g value was used to estimate the effect of each dietary intervention relative to the placebo. RESULTS: In this meta-analysis, we examined 13 double-blind randomized clinical trials, comprising a total of 570 patients with ASD: 293 in the intervention group and 277 in the placebo group. Antioxidants (N-acetylcysteine (NAC), other antioxidants) are more effective than placebos in improving the irritability among symptoms in the ABC and communication disturbance symptoms in the DBC. There was a good trend of improvement in the stereotypic behavior symptoms in the ABC. Treatment with NAC antioxidants showed a good trend of improvement in irritability in the ABC and symptoms of hyperactivity. The effect size was small, and there was a low risk of statistical heterogeneity and publication bias. LIMITATIONS: The number of studies in this meta-analysis was small and the sample size was small. CONCLUSION: This meta-analysis suggests that antioxidant intervention has a potential role in the management of some symptoms in patients with ASD, and indicates the feasibility of using antioxidants to treat autism in the future.

FEN1 is a prognostic biomarker for ER+ breast cancer and associated with tamoxifen resistance through the ERα/cyclin D1/Rb axis.

BACKGROUND: Tamoxifen is an important choice in endocrine therapy for patients with oestrogen receptor-positive (ER+) breast cancer, and disease progression-associated resistance to tamoxifen therapy is still challenging. Flap endonuclease-1 (FEN1) is used as a prognostic biomarker and is considered to participate in proliferation, migration, and drug resistance in multiple cancers, especially breast cancer, but the prognostic function of FEN1 in ER+ breast cancer, and whether FEN1 is related to tamoxifen resistance or not, remain to be explored. METHODS: On-line database Kaplan-Meier (KM) plotter, GEO datasets, and immunohistochemistry were used to analyse the prognostic value of FEN1 in ER+ breast cancer from mRNA and protein levels. Cell viability assay and colony formation assays showed the response of tamoxifen in MCF-7 and T47D cells. Microarray data with FEN1 siRNA versus control group in MCF-7 cells were analysed by Gene Set Enrichment Analysis (GSEA). The protein levels downstream of FEN1 were detected by western blot assay. RESULTS: ER+ breast cancer patients who received tamoxifen for adjuvant endocrine therapy with poor prognosis showed a high expression of FEN1. MCF-7 and T47D appeared resistant to tamoxifen after FEN1 over-expression and increased sensitivity to tamoxifen after FEN1 knockdown. Importantly, FEN1 over-expression could activate tamoxifen resistance through the ERα/cyclin D1/Rb axis. CONCLUSIONS: As a biomarker of tamoxifen effectiveness, FEN1 participates in tamoxifen resistance through ERα/cyclin D1/Rb axis. In the future, reversing tamoxifen resistance by knocking-down FEN1 or by way of action as a small molecular inhibitor of FEN1 warrants further investigation.

Cross-talk between the ER pathway and the lncRNA MAFG-AS1/miR-339-5p/ CDK2 axis promotes progression of ER+ breast cancer and confers tamoxifen resistance.

Hormone receptor-positive breast cancer accounts for around 75% of breast cancers. The estrogen receptor pathway promotes tumor progression and endocrine resistance. Recently, the cross-talk between the ER signaling pathway and cell cycle regulation has been identified. It is necessary to determine the underlying molecular mechanisms involved in the ER signaling pathway and find new target genes for prognosis and drug resistance in ER+ breast cancer. In this study, lncRNA MAFG-AS1 was shown to be up-regulated and associated with poor prognosis in ER+ breast cancer. Functionally, down-regulation of MAFG-AS1 could inhibit cell proliferation and promote apoptosis. In addition, MAFG-AS1 which contained an estrogen-responsive element could promote CDK2 expression by sponging miR-339-5p. Subsequently, MAFG-AS1 and CDK2 were found to be up-regulated in tamoxifen-resistant MCF-7 cells. Cross-talk between the ER signaling pathway and cell cycle conducted by MAFG-AS1 and CDK2 could promote tamoxifen resistance. In conclusion, our study indicated that estrogen-responsive lncRNA MAFG-AS1 up-regulated CDK2 by sponging miR-339-5p, which promoted ER+ breast cancer proliferation. Cross-talk between the ER signaling pathway and cell cycle suggested that lncRNA MAFG-AS1 is a potential biomarker and therapeutic target in ER+ breast cancer. CDK2 inhibitors may be applied to endocrine resistance therapy.

Biological and clinical significance of flap endonuclease­1 in triple­negative breast cancer: Support of metastasis and a poor prognosis.

Flap endonuclease­1 (FEN1), a structure­specific nuclease participating in DNA replication and repair processes, has been confirmed to promote the proliferation and drug resistance of tumor cells. However, the biological functions of FEN1 in cancer cell migration and invasion have not been defined. In the present study, using online database analysis and immunohistochemistry of the specimens, it was found that FEN1 expression was associated with a highly invasive triple­negative breast cancer (TNBC) subtype in both breast cancer samples from the Oncomine database and from patients recruited into the study. Furthermore, FEN1 was an important biomarker of lymph node metastasis and poor prognosis in patients with TNBC. FEN1 promoted migration of TNBC cell lines and FEN1 knockdown reduced the number of spontaneous lung metastasis in vivo. Ingenuity Pathway Analysis of FEN1­related transcripts in 198 patients with TNBC demonstrated that the polo­like kinase family may be the downstream target of FEN1. PLK4 was further identified as a critical target of FEN1 mediating TNBC cell migration, by regulating actin cytoskeleton rearrangement. The results of the present study validate FEN1 as a therapeutic target in patients with TNBC and revealed a new role for FEN1 in regulating TNBC invasion and metastasis.

Prognostic Value and Influence of Receptor Conversion on Treatment Regimen in Metastatic Breast Cancer at the First Time of Recurrence.

PURPOSE: At the first time of metastatic breast cancer recurrence, conversion of the receptors status may occur between primary lesions and metastatic lesions, including the estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). Whether the decision of the treatment regimen is based on the primary receptor status or that of metastatic lesions is still unclear. METHODS: This study enrolled 411 female patients with a diagnosis of metastatic breast cancer at the first time of recurrence to explore the influence of receptor conversion on prognosis prediction and treatment regimen of patients with metastatic breast cancer. RESULTS: ER and PR changes from negative to positive are both prognostic factors for patients with breast cancer. Patients receiving endocrine therapy showed a better survival after recurrence than those using chemotherapy alone in the ER or PR Prim- Met+ subgroup. Patients in the HER2 Prim- Met+ subgroup using HER2-targeted therapy in multilines showed a post-recurrence survival advantage. In the bone re-biopsy subgroup, the PR change from positive to negative appeared to be more frequent than at other re-biopsy sites. CONCLUSIONS: Patients with metastatic breast cancer should perform re-biopsy to clarify the receptor status of the first metastatic lesions, which may provide clinicians valuable evidence to conduct treatments with higher precision.

Oxidative Stress Marker Aberrations in Multiple Sclerosis: A Meta-Analysis Study.

Oxidative stress has been suggested to play a key role in multiple sclerosis (MS), but clinical data on oxidative stress markers in MS patients were inconsistent. This study sought to quantitatively summarize the data of oxidative stress markers in the blood and cerebrospinal fluid (CSF) of patients with MS in the literature. We conducted a systematic search of PubMed and Web of Science and included studies if they provided data on the concentrations of oxidative stress markers in the peripheral blood and CSF of MS patients and healthy control (HC) subjects. The systematic search resulted in the inclusion of 31 studies with 2,001 MS patients and 2,212 HC subjects for meta-analysis. Random-effects meta-analysis demonstrated that patients with MS had significantly increased concentrations of blood oxidative stress markers compared with HC subjects for malondialdehyde (MDA; Hedges' g, 2.252; 95% CI, 1.080 to 3.424; p < 0.001) and lipid hydroperoxide by tert-butyl hydroperoxide-initiated chemiluminescence (CL-LOOH; Hedges' g, 0.383; 95% CI, 0.065 to 0.702; p = 0.018). In contrast, concentrations of albumin (Hedges' g, -1.036; CI, -1.679 to -0.394; p = 0.002) were significantly decreased in MS patients when compared with those in HC subjects. However, the other analyzed blood oxidative stress markers did not show significant differences between cases and controls. Furthermore, this meta-analysis showed significant association between CSF MDA and MS (Hedges' g, 3.275; 95% CI, 0.859 to 5.691; p = 0.008). Taken together, our results revealed increased blood and CSF MDA and decreased blood albumin levels in patients with MS, strengthening the clinical evidence of increased oxidative stress in MS.

GALNT6 promotes breast cancer metastasis by increasing mucin-type O-glycosylation of α2M.

Breast cancer is the most lethal malignancy in women. N-acetylgalactosaminyltransferase 6 (GALNT6) is an enzyme which mediates the initial step of mucin-type O-glycosylation, and has been reported to be involved in mammary carcinogenesis. However, the molecular mechanism of GALNT6 in breast cancer metastasis has not been fully explored. In this study, based on online database analyses and tissue microarrays, the overall survival (OS) of breast cancer patients with high expression of GALNT6 was found to be shorter than those with low expression of GALNT6. Also, high GALNT6 expression was positively correlated with advanced pN stage and pTNM stage. GALNT6 was shown to be able to promote the migration and invasion of breast cancer cells, and enhance the level of mucin-type O-glycosylation of substrates in the supernatants of breast cancer cells. Qualitative mucin-type glycosylomics analysis identified α2M as a novel substrate of GALNT6. Further investigation showed that GALNT6 increased O-glycosylation of α2M, and the following activation of the downstream PI3K/Akt signaling pathway was involved in the promotion of migration and invasion of breast cancer cells. This study identified a new substrate of GALNT6 and provides novel understanding of the role of GALNT6 in promoting metastasis and poor prognosis in breast cancer.

Inhibition of FEN1 Increases Arsenic Trioxide-Induced ROS Accumulation and Cell Death: Novel Therapeutic Potential for Triple Negative Breast Cancer.

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer, which is very difficult to treat and commonly develops resistance to chemotherapy. The following study investigated whether the inhibition of Flap Endonuclease 1 (FEN1) expression, the key enzyme in the base excision repair (BER) pathway, could improve the anti-tumor effect of arsenic trioxide (ATO), which is a reactive oxygen species (ROS) inducer. Our data showed that ATO could increase the expression of FEN1, and the knockdown of FEN1 could significantly enhance the sensitivity of TNBC cells to ATO both in vitro and in vivo. Further mechanism studies revealed that silencing FEN1 in combination with low doses of ATO might increase intracellular ROS and reduce glutathione (GSH) levels, by reducing the nuclear translocation of nuclear factor erythroid 2-related factor 2 (Nrf2); elevating ROS leaded to apoptosis and p38 and JNK pathway activating. In conclusion, our study suggested the combination of FEN1 knockdown and ATO could induce TNBC cell death by promoting ROS production. FEN1 knockdown can effectively decrease the application concentrations of ATO, thus providing a possibility for the treatment of TNBC with ATO.

MiR-891a-5p as a prognostic marker and therapeutic target for hormone receptor-positive breast cancer.

Background: Breast cancer is one of the most frequent malignant tumors worldwide, with 1.67 million newly-diagnosed cases and 522,000 deaths each year. Therefore, seeking the novel biomarkers and therapeutic targets that contribute to postoperative recurrence and metastasis in patients with breast cancer is emerging and facilitates the development of innovative therapeutics. Methods: Retrieving the dataset of patients with hormone receptor (HR)-positive breast cancers from Gene Expression Omnibus (GEO) and collecting the data from the patients with HR-positive breast cancers enrolled in the First Affiliated Hospital of China Medical University are so as to identify the miRNAs associated with metastasis and distant metastasis-free survival (DMFS). Then MTT and Transwell migration assays were used to validate the effect of miRNAs on cell proliferation and migration of estrogen receptor-positive breast cancer T47D and MCF7 cells in vitro, respectively. Results: From GSE59829 dataset, the miRNA expression levels of miR-891a-5p, miR-383-5p and miR-1295a were significantly downregulated while the levels of miR-128-3p, miR-661 and miR-296-3p were significantly upregulated in breast cancers from patients with metastasis as compared to the matched non-metastatic group. Moreover, low expression levels of miR-891a-5p, miR-383-5p and miR-1295a or high expression levels of miR-128-3p, miR-661 and miR-296-3p were respectively associated with low DMFS in patients with breast cancer. Our clinical cohort study supported that the levels of miR-891a-5p, miR-383-5p and miR-1295a were significantly lower in breast cancers from the metastasis group when compared with non-metastatic group. However, there is no significant difference with regard to the levels of miR-128-3p, miR-661 and miR-296-3p in breast cancer between these two groups. Moreover, low expression levels of miR-891a-5p and miR-383-5p but not miR-1295a in breast cancer were significantly associated with low DMFS in patients, implying that the expression of miR-891a-5p and miR-383-5p were the potential prognosis markers for metastatic human breast cancers. Further investigation disclosed that miR-891a-5p but not miR-383-5p restrained both proliferation and migration of T47D and MCF7 cells. In silico analysis of miRNAs target gene through online computational algorithms revealed that A Disintegrin and metalloproteinase domain-containing protein 10 (ADAM10) is the downstream target for miR-891a-5p. Further study confirmed that miR-891a-5p impeded ADAM10 expression by directly binding to its 3'UTR, leading to the inhibition of breast cancer cells proliferation and migration. Moreover, silencing ADAM10 inhibited T47D and MCF7 cells growth and migration. Conclusion: miR-891a-5p is the vital prognostic marker for HR-positive breast cancer. In addition, miR-891a-5p and miR-383-5p are the potential targets for HR-positive breast cancer therapeutics.

Sesquiterpenoids from Artemisia vestita and Their Antifeedant and Antifungal Activities.

Four new sesquiterpenoids, named artemivestinolide D-G (1-4) and three known sesquiterpenoids (5-7), were isolated from Artemisia vestita. The structures of these new compounds were determined based on extensive spectroscopic data analyses. Furthermore, the electronic circular dichroism data determined the absolute configurations of the new compounds. The antifeedant and antifungal activities of the isolates were evaluated against third-instar larvae of Plutella xylostella and three plant pathogenic fungi. Compounds 1-7 showed moderate antifeedant activities and compounds 1-4 and 6-7 exhibited antifungal activities.

Prediction of the RNA Secondary Structure Using a Multi-Population Assisted Quantum Genetic Algorithm.

Quantum-inspired genetic algorithms (QGAs) were recently introduced for the prediction of RNA secondary structures, and they showed some superiority over the existing popular strategies. In this paper, for RNA secondary structure prediction, we introduce a new QGA named multi-population assisted quantum genetic algorithm (MAQGA). In contrast to the existing QGAs, our strategy involves multi-populations which evolve together in a cooperative way in each iteration, and the genetic exchange between various populations is performed by an operator transfer operation. The numerical results show that the performances of existing genetic algorithms (evolutionary algorithms [EAs]), including traditional EAs and QGAs, can be significantly improved by using our approach. Moreover, for RNA sequences with middle-short length, the MAQGA improves even this state-of-the-art software in terms of both prediction accuracy and sensitivity.

Peripheral Blood and Cerebrospinal Fluid Cytokine Levels in Guillain Barré Syndrome: A Systematic Review and Meta-Analysis.

Background: Guillain Barré Syndrome (GBS) is an autoimmune disorder caused by the immune-mediated damage of the peripheral nervous system. Increasing evidence suggests that inflammatory cytokines are important mediators for the onset and progression of GBS. A number of clinical studies have demonstrated elevated levels of T helper-1 (Th1-), Th2-, and Th17-related cytokines in patients with GBS; however, the results were inconsistent across studies. Methods: We performed a systematic review and a meta-analysis of studies comparing the levels of inflammatory cytokines in the cerebrospinal fluid and peripheral blood between patients with GBS and healthy individuals, using Comprehensive Meta-Analysis Version 2 software. A database search identified 30 studies comprising 1,302 patients with GBS and 1,073 healthy controls. Results: The random-effects meta-analysis demonstrated that peripheral blood tumor necrosis factor-α (Hedges g, 1.544; 95% confidence interval (CI), 0.923-2.165; p < 0.001), interleukin-1ß (IL-1ß; Hedges g, 0.678; 95% CI, 0.183-1.172; p = 0.007), IL-6 (Hedges g, 0.630; 95% CI, 0.100-1.160; p = 0.02), IL-4 (Hedges g, 0.822; 95% CI, 0.220-1.423; p = 0.007), IL-17 (Hedges g, 1.452; 95% CI, 0.331-2.573; p = 0.011), interferon-γ (Hedges g, 1.104; 95% CI, 0.490-1.719; p < 0.001), and C-reactive protein (Hedges g, 0.909; 95% CI, 0.453-1.365; p < 0.001) levels were significantly increased in patients with GBS when compared with healthy controls. Contrastingly, the blood IL-10 and transforming growth factor-ß levels were not significantly associated with GBS. Furthermore, the meta-analysis found that cerebrospinal fluid IL-17 levels were significantly associated with GBS (Hedges g, 1.882; 95% CI, 0.104-3.661; p = 0.038). Conclusion: Altogether, our results clarified the circulating inflammatory cytokine profile in patients with GBS, and revealed that Th1-, Th2-, and Th17-related cytokines were highly elevated in the GBS patients, suggesting the potential use of these cytokines as biomarkers for GBS.

FEN1 mediates miR-200a methylation and promotes breast cancer cell growth via MET and EGFR signaling.

Flap endonuclease 1 (FEN1) is recognized as a pivotal factor in DNA replication, long-patch excision repair, and telomere maintenance. Excessive FEN1 expression has been reported to be closely associated with cancer progression, but the specific mechanism has not yet been explored. In the present study, we demonstrated that FEN1 promoted breast cancer cell proliferation via an epigenetic mechanism of FEN1-mediated up-regulation of DNA methyltransferase (DNMT)1 and DNMT3a. FEN1 was proved to interact with DNMT3a through proliferating cell nuclear antigen (PCNA) to suppress microRNA (miR)-200a-5p expression mediated by methylation. Furthermore, miR-200a-5p was identified to repress breast cancer cell proliferation by inhibiting the expression of its target genes, hepatocyte growth factor (MET), and epidermal growth factor receptor (EGFR). Overall, our data surprisingly demonstrate that FEN1 promotes breast cancer cell growth via the formation of FEN1/PCNA/DNMT3a complex to inhibit miR-200a expression by DNMT-mediated methylation and to recover the target genes expression of miR-200a, MET, and EGFR. The novel epigenetic mechanism of FEN1 on proliferation promotion provides a significant clue that FEN1 might serve as a predictive biomarker and therapeutic target for breast cancer.-Zeng, X., Qu, X., Zhao, C., Xu, L., Hou, K., Liu, Y., Zhang, N., Feng, J., Shi, S., Zhang, L., Xiao, J., Guo, Z., Teng, Y., Che, X. FEN1 mediates miR-200a methylation and promotes breast cancer cell growth via MET and EGFR signaling.

Aquilariaenes A-H, eight new diterpenoids from Chinese eaglewood.

Aquilariaenes A-H (1-8), eight new diterpenoids and nor-diterpenoids (1-8) belonging to abietane or pimarane, were isolated from the petroleum ether extract of Chinese eaglewood. Their structures were elucidated on the basis of extensive spectroscopic methods including HRESIMS, IR, 1D and 2D NMR spectroscopic data analyses. Antidepressant activities of isolates for in vitro inhibition of serotonin and norepinephrine reuptake in rat brain synaptosomes were evaluated.

C-Cbl reverses HER2-mediated tamoxifen resistance in human breast cancer cells.

BACKGROUND: Tamoxifen is a frontline therapy for estrogen receptor (ER)-positive breast cancer in premenopausal women. However, many patients develop resistance to tamoxifen, and the mechanism underlying tamoxifen resistance is not well understood. Here we examined whether ER-c-Src-HER2 complex formation is involved in tamoxifen resistance. METHODS: MTT and colony formation assays were used to measure cell viability and proliferation. Western blot was used to detect protein expression and protein complex formations were detected by immunoprecipitation and immunofluorescence. SiRNA was used to examine the function of HER2 in of BT474 cells. An in vivo xenograft animal model was established to examine the role of c-Cbl in tumor growth. RESULTS: MTT and colony formation assay showed that BT474 cells are resistant to tamoxifen and T47D cells are sensitive to tamoxifen. Immunoprecipitation experiments revealed ER-c-Src-HER2 complex formation in BT474 cells but not in T47D cells. However, ER-c-Src-HER2 complex formation was detected after overexpressing HER2 in T47D cells and these cells were more resistant to tamoxifen. HER2 knockdown by siRNA in BT474 cells reduced ER-c-Src-HER2 complex formation and reversed tamoxifen resistance. ER-c-Src-HER2 complex formation was also disrupted and tamoxifen resistance was reversed in BT474 cells by the c-Src inhibitor PP2 and HER2 antibody trastuzumab. Nystatin, a lipid raft inhibitor, reduced ER-c-Src-HER2 complex formation and partially reversed tamoxifen resistance. ER-c-Src-HER2 complex formation was disrupted by overexpression of c-Cbl but not by the c-Cbl ubiquitin ligase mutant. In addition, c-Cbl could reverse tamoxifen resistance in BT474 cells, but the ubiquitin ligase mutant had no effect. The effect of c-Cbl was validated in BT474 tumor-bearing nude mice in vivo. Immunofluorescence also revealed ER-c-Src-HER2 complex formation was reduced in tumor tissues of nude mice with c-Cbl overexpression. CONCLUSIONS: Our results suggested that c-Cbl can reverse tamoxifen resistance in HER2-overexpressing breast cancer cells by inhibiting the formation of the ER-c-Src-HER2 complex.

SIRT5 as a biomarker for response to anthracycline-taxane-based neoadjuvant chemotherapy in triple-negative breast cancer.

Neoadjuvant chemotherapy (NAC) is of great importance for patients with triple-negative breast cancer (TNBC) and the achievement of pathological complete response (pCR) to NAC in TNBC patients indicates survival benefits. However, the identification of reliable predictive biomarkers of pCR to NAC in TNBC patients remains an urgent and largely unattended medical issue. In the present study, we evaluated the differentially expressed genes (DEGs) between pCR and non-pCR patients after doxorubicin/cyclophosphamide therapy, followed by paclitaxel pre-operative treatment in 64 TNBC patients recorded in the GSE41998 dataset of Gene Expression Omnibus and identified 118 DEGs. Subsequently, we selected five core genes that were closely associated with the pCR of TNBC patients by using a genetic algorithm­support vector machine-based method. Sirtuin 5 (SIRT5) was one of the five core genes and patients who achieved pCR expressed higher levels of SIRT5. Thus, we speculated that SIRT5 may be a potential predictive marker of the response to anthracycline-taxane-based chemotherapy. Oncomine analysis revealed that the expression levels of SIRT5 were higher in epirubicin/cyclophosphamide-docetaxel responders compared with non-responders. Furthermore, Gene Ontology analysis indicated that SIRT5 may affect the response to anthracycline-taxane-based chemotherapy by regulating the Rho pathway. It was also observed that SIRT5 was upregulated in TNBC and breast cancer with BRCA1 mutation subtypes. High SIRT5 expression was also associated with poor clinical outcomes of breast cancer patients. In conclusion, the present study revealed SIRT5 as a biomarker for response to anthracycline-taxane-based NAC in patients with TNBC and identified a series of novel biological functions of SIRT5 in breast cancer.