A trispecific antibody targeting HER2 and T cells inhibits breast cancer growth via CD4 cells.

Effective antitumour immunity depends on the orchestration of potent T cell responses against malignancies1. Regression of human cancers has been induced by immune checkpoint inhibitors, T cell engagers or chimeric antigen receptor T cell therapies2-4. Although CD8 T cells function as key effectors of these responses, the role of CD4 T cells beyond their helper function has not been defined. Here we demonstrate that a trispecific antibody to HER2, CD3 and CD28 stimulates regression of breast cancers in a humanized mouse model through a mechanism involving CD4-dependent inhibition of tumour cell cycle progression. Although CD8 T cells directly mediated tumour lysis in vitro, CD4 T cells exerted antiproliferative effects by blocking cancer cell cycle progression at G1/S. Furthermore, when T cell subsets were adoptively transferred into a humanized breast cancer tumour mouse model, CD4 T cells alone inhibited HER2+ breast cancer growth in vivo. RNA microarray analysis revealed that CD4 T cells markedly decreased tumour cell cycle progression and proliferation, and also increased pro-inflammatory signalling pathways. Collectively, the trispecific antibody to HER2 induced T cell-dependent tumour regression through direct antitumour and indirect pro-inflammatory/immune effects driven by CD4 T cells.

Bidirectional transport of amino acids regulates mTOR and autophagy.

Amino acids are required for activation of the mammalian target of rapamycin (mTOR) kinase which regulates protein translation, cell growth, and autophagy. Cell surface transporters that allow amino acids to enter the cell and signal to mTOR are unknown. We show that cellular uptake of L-glutamine and its subsequent rapid efflux in the presence of essential amino acids (EAA) is the rate-limiting step that activates mTOR. L-glutamine uptake is regulated by SLC1A5 and loss of SLC1A5 function inhibits cell growth and activates autophagy. The molecular basis for L-glutamine sensitivity is due to SLC7A5/SLC3A2, a bidirectional transporter that regulates the simultaneous efflux of L-glutamine out of cells and transport of L-leucine/EAA into cells. Certain tumor cell lines with high basal cellular levels of L-glutamine bypass the need for L-glutamine uptake and are primed for mTOR activation. Thus, L-glutamine flux regulates mTOR, translation and autophagy to coordinate cell growth and proliferation.

Recognition Imaging of Trace E-cadherins on the Bladder Cancer Cells Surface during Epithelial-Mesenchymal Transition by Force-Distance Curve-Based AFM.

Tumor-associated epithelial-mesenchymal transition (EMT) contains a set of transitional cellular states usually judged by the EMT marker expression. E-cadherin is a down-regulated EMT epithelial marker, and the detection of E-cadherin is challenging on cancer cell surfaces in the middle and late stages of EMT. Here, the trace E-cadherins on the living bladder cancer T24 cell surface during EMT were investigated with force-distance curve-based atomic force microscopy. The results confirmed that T24 cells are still in an intermediate state and can be transferred into the mesenchymal phenotype by long-term TGF-ß1 induction. During EMT, E-cadherins on the T24 cell surface gradually decreased and rarely clustered. E-cadherin is not completely missing, even at the end of EMT, but is too sparse to cluster. This work provides us with a visual understanding of the expression and distribution of trace markers during EMT and a deep comprehension of the indispensable significance of E-cadherin in cancer cells.

Preliminary study on dosimetry characteristics of a novel cylindrical dose verification system.

OBJECTIVE: To develop a novel ionization chamber array dosimetry system, study its dosimetry characteristics, and perform preliminary tests for plan dose verification. METHODS: The dosimetry characteristics of this new array were tested, including short-term and long-term reproducibility, dose linearity, dose rate dependence, field size dependence, and angular dependence. The open field and MLC field plans were designed for dose testing. Randomly select 30 patient treatment plans (10 intensity-modulated radiation therapy [IMRT] plans and 20 volumetric modulated arc therapy [VMAT] plans) that have undergone dose verification using Portal Dosimetry to perform verification measurement and evaluate dose verification test results. RESULTS: The dosimetry characteristics of the arrays all performed well. The gamma passing rates (3%/2 mm) were more than 96% for the combined open field and MLC field plans. The average gamma pass rates were (99.54 ± 0.58)% and (96.70 ± 3.41)% for the 10 IMRT plans and (99.32 ± 0.89)% and (94.91 ± 6.01)% for the 20 VMAT plans at the 3%/2 mm and 2%/2 mm criteria, respectively, which is similar to the Portal Dosimetry's measurement results. CONCLUSIONS: This novel ionization chamber array demonstrates good dosimetry characteristics and is suitable for clinical IMRT and VMAT plan verifications.

Neoadjuvant endocrine therapy for strongly hormone receptor-positive and HER2-negative early breast cancer: results of a prospective multi-center study.

PURPOSE: For estrogen receptor (ER)-positive breast cancer, neoadjuvant endocrine therapy (NET) has been shown to be as effective as neoadjuvant chemotherapy (NACT). We evaluated the prognostic significance of Preoperative Endocrine Prognostic Index (PEPI). METHODS: We conducted a prospective, multi-center, non-randomized, controlled trial that enrolled postmenopausal early-stage strongly ER-positive (≥ 50%) and HER2-negative breast cancer patients. All patients were given 4-month NET before surgery. The primary objective was to investigate the 5-year recurrence-free survival (RFS) in patients who had PEPI 0-1 or pathological complete response (pCR) without chemotherapy. Patients who had PEPI 0-1 or pCR were recommended to receive adjuvant endocrine therapy only and patients had PEPI ≥ 2 may receive adjuvant chemotherapy at the discretion of the treating physician. RESULTS: A total of 410 patients were included and 352 patients constituted the per-protocol population. Overall, 9 patients (2.5%) had pCR (ypT0/is ypN0), 128 patients (36.4%) had PEPI = 0, and 56 patients (15.9%) had PEPI = 1. After a median follow-up of 60 months (4-104 months), patients who had PEPI 0-1 or pCR showed an improved 5-year RFS [99.5% (95% CI 98.5-99.9%) for PEPI 0-1 or pCR group vs. 93.7% (95% CI 89.6-97.8%) for PEPI ≥ 2 group, P = 0.028]. No survival difference was detected between patients received adjuvant chemotherapy vs. no chemotherapy among PEPI ≥ 2 cases. CONCLUSION: PEPI 0-1 or pCR may be used to define a group of ER-positive and HER2-negative postmenopausal early breast cancer patients with low relapse risk for whom adjuvant chemotherapy can be safely withheld. Studies on the identification and alternative treatment options for endocrine-resistant tumors are warranted. CLINICAL TRIAL REGISTRATION: NCT01613560.

Toripalimab combined with concurrent platinum-based Chemoradiotherapy in patients with locally advanced cervical Cancer: an open-label, single-arm, phase II trial.

BACKGROUND: Concurrent chemoradiotherapy is currently the standard of care for patients with locally advanced cervical cancer. However, even with the application of modern radiotherapy techniques, a considerable number of patients still develop distant metastases. PD-L1 inhibitors show good efficacy in cervical cancer. This single-arm phase II study aims to explore the efficacy and tolerability of combining PD-L1 inhibitor with concurrent chemoradiotherapy in the treatment of locally advanced cervical cancer. METHODS/DESIGN: The primary endpoint of the study was the objective response rate assessed according to RECIST v1.1 criteria. The inclusion criteria were previously untreated patients aged 18-75 years with stage III-IVA (FIGO 2018 staging system) locally advanced cervical cancer. During concurrent chemoradiotherapy and consolidation chemotherapy, the enrolled patients will receive toripalimab (240 mg) every 3 weeks. After consolidation chemotherapy, the enrolled patients will be treated with toripalimab (240 mg) once every 6 weeks until the whole treatment cycle reaches 1 year. Intensity modulated radiotherapy was used for external beam radiation, and high-dose rate brachytherapy was delivered under image-guidance. Weekly DDP (40 mg/m2) was given concurrently with radiotherapy while 6 cycles of consolidated chemotherapy (paclitaxel plus DDP) were given after radiotherapy every three weeks. Secondary objectives included safety and tolerability, toxicity profile, progression-free survival, and overall survival. DISCUSSION: PD-L1 inhibitor has shown good efficacy in recurrent/metastatic cervical cancer. However, there is still a lack of evidence about its combination with concurrent chemoradiotherapy in the treatment of locally advanced cervical cancer. The purpose of this study is to explore the efficacy and tolerance of this combination therapy, so as to lay the foundation for the future phase III randomized study. TRIAL REGISTRATION:  clinicaltrials.gov NCT05084677 . Retrospectively registered on Octorber 07, 2021.

Anti-CD38 monoclonal antibody interference with blood compatibility testing: Differentiating isatuximab and daratumumab via functional epitope mapping.

BACKGROUND: There are two FDA-approved anti-CD38 monoclonal antibodies for treatment of multiple myeloma: isatuximab and daratumumab. Owing to expression of CD38 on reagent red blood cells (RBCs), these antibodies interfere with indirect antiglobulin tests (IATs). We sought to understand differences in such interference by performing binding experiments. STUDY DESIGN AND METHODS: In vitro experiments to compare the binding to RBCs of isatuximab and daratumumab alone or in the presence of a mouse anti-human CD38 antibody (HB-7 or AT13/5) or a nicotinamide adenine dinucleotide-analog CD38 inhibitor were performed and quantified by flow cytometry, imaging, mass spectrometry, surface plasmon resonance, and LigandTracer technologies. Serologic testing was performed on plasma samples spiked with isatuximab or daratumumab. RESULTS: CD38 expressed on RBCs can be directly bound by daratumumab, whereas isatuximab requires a co-factor, such as HB-7, AT13/5, or a CD38 inhibitor, suggesting that the isatuximab epitope on RBCs is masked in vitro. Daratumumab samples more frequently showed interference and had stronger reactions than isatuximab samples. Dithiothreitol treatment was equally effective in mitigating the interference caused by either drug. DISCUSSION: Both isatuximab and daratumumab interfere with IATs but at different magnitudes, reflecting distinct binding to CD38 on RBCs. From the binding studies, we conclude that the isatuximab epitope on RBCs is masked in vitro and binding requires a certain CD38 conformation or co-factor. This circumstance may explain why interference is seen only in a subset of patients receiving isatuximab when compared with interference seen in most patients on daratumumab therapy.

The protective effect of biomineralized BSA-Mn3O4 nanoparticles on HUVECs investigated by atomic force microscopy.

Manganese-based nanozymes have been widely used in the field of cell protection due to their various enzyme-mimicking activities, but their effect on the mechanical properties of cells is not yet known. Here, bovine serum albumin-modified Mn3O4 nanoparticles (BSA-Mn3O4 NPs) with good biocompatibility were synthesized by a one-step biomineralization method using BSA as a template. BSA-Mn3O4 NPs possess scavenging activity against superoxide free radicals (O2˙-), hydroxyl radicals (˙OH) and hydrogen peroxide (H2O2). The excellent reactive oxygen species (ROS) scavenging activity of BSA-Mn3O4 NPs enables them to effectively reduce the intracellular ROS level, thus mitigating the damage of oxidative stress on human umbilical vein endothelial cells (HUVECs). Subsequently, the intracellular antioxidant mechanism of the BSA-Mn3O4 NPs was further investigated. The results show that the BSA-Mn3O4 NPs could inhibit the depolymerization of F-actin, help cells maintain their normal morphology, and reduce the decrease in Young's modulus of cells caused by oxidative stress.

Evaluation of a beneficial effect of adjuvant chemotherapy in patients with stage I triple-negative breast cancer: a population-based study using the SEER 18 database.

PURPOSE: To evaluate the effect of adjuvant chemotherapy on improving the prognosis of patients with stage I triple-negative breast cancer (TNBC). METHODS: TNBC patients diagnosed in the SEER 18 database from 2010 to 2015 were included. Kaplan-Meier plots and log-rank tests were used to compare the differences in breast cancer-specific survival (BCSS) and overall survival (OS) between subgroups of variables. A Cox proportional hazard model was used to determine the prognostic factors affecting BCSS and OS. RESULTS: A total of 9256 patients were enrolled in this study. Among these patients, 380 died from breast cancer, and 703 died from all causes. Patients who received chemotherapy had significantly better BCSS and OS than those who did not receive chemotherapy for stage T1cN0M0 (BCSS, hazard ratio (HR) = 0.68, 95% confidence interval (CI) 0.51-0.90; OS, HR = 0.54, 95% CI 0.44-0.67) and stage IB (BCSS, HR = 0.39, 95% CI 0.16-0.95; OS, HR = 0.41, 95% CI 0.19-0.87) disease. Patients who received chemotherapy did not have significantly better BCSS or OS than those who did not receive chemotherapy for stage T1aN0M0 or T1bN0M0 disease. The patients who received chemotherapy in the poorly differentiated and undifferentiated groups had better BCSS (HR = 0.68, 95% CI 0.52-0.88) and OS (HR = 0.54, 95% CI 0.44-0.66) than the patients who did not receive chemotherapy. CONCLUSION: According to current clinical guidelines, patients with stage T1bN0M0 TNBC are probably overtreated. The prognosis of these patients with stage T1aN0M0 or T1bN0M0 disease is good enough that adjuvant chemotherapy cannot improve it further.

Methionyl-tRNA synthetase inhibitor has potent in vivo activity in a novel Giardia lamblia luciferase murine infection model.

BACKGROUND: Methionyl-tRNA synthetase (MetRS) inhibitors are under investigation for the treatment of intestinal infections caused by Giardia lamblia. OBJECTIVES: To properly analyse the therapeutic potential of the MetRS inhibitor 1717, experimental tools including a robust cell-based assay and a murine model of infection were developed based on novel strains of G. lamblia that employ luciferase reporter systems to quantify viable parasites. METHODS: Systematic screening of Giardia-specific promoters and luciferase variants led to the development of a strain expressing the click beetle green luciferase. Further modifying this strain to express NanoLuc created a dual reporter strain capable of quantifying parasites in both the trophozoite and cyst stages. These strains were used to develop a high-throughput cell assay and a mouse infection model. A library of MetRS inhibitors was screened in the cell assay and Compound-1717 was tested for efficacy in the mouse infection model. RESULTS: Cell viability in in vitro compound screens was quantified via bioluminescence readouts while infection loads in mice were monitored with non-invasive whole-animal imaging and faecal analysis. Compound-1717 was effective in clearing mice of Giardia infection in 3 days at varying doses, which was supported by data from enzymatic and phenotypic cell assays. CONCLUSIONS: The new in vitro and in vivo assays based on luciferase expression by engineered G. lamblia strains are useful for the discovery and development of new therapeutics for giardiasis. MetRS inhibitors, as validated by Compound-1717, have promising anti-giardiasis properties that merit further study as alternative therapeutics.

Gut microbial dysbiosis is associated with development and progression of radiation enteritis during pelvic radiotherapy.

Radiation enteritis (RE) is the most common complication of radiotherapy for pelvic irradiation receivers. Herein we investigated the alterations in gut microbial profiles and their association with enteritis in patients undergoing pelvic radiotherapy. Faecal samples were collected from 18 cervical cancer patients during radiotherapy. Microbiota profiles were characterized based on 16S rRNA sequencing using the Illumina HiSeq platform. Epithelial inflammatory response was evaluated using bacterial-epithelial co-cultures. Dysbiosis was observed among patients with RE, which was characterized by significantly reduced α-diversity but increased ß-diversity, relative higher abundance of Proteobacteria and Gammaproteobacteria and lower abundance of Bacteroides. Coprococcus was clearly enriched prior to radiotherapy in patients who later developed RE. Metastat analysis further revealed unique grade-related microbial features, such as more abundant Virgibacillus and Alcanivorax in patients with mild enteritis. Additionally, using bacterial-epithelial co-cultures, RE patient-derived microbiota induced epithelial inflammation and barrier dysfunction, enhanced TNF-α and IL-1ß expression compared with control microbiota. Taken together, we define the overall picture of gut microbiota in patients with RE. Our results suggest that dysbiosis of gut microbiota may contribute to development and progression of RE. Gut microbiota can offer a set of biomarkers for prediction, disease activity evaluation and treatment selection in RE.

PIWI-interacting RNA-36712 restrains breast cancer progression and chemoresistance by interaction with SEPW1 pseudogene SEPW1P RNA.

BACKGROUND: Breast cancer is one of the most common malignancies and the major cause of cancer-related death in women. Although the importance of PIWI-interacting RNAs (piRNAs) in cancer has been increasingly recognized, few studies have been explored the functional mechanism of piRNAs in breast cancer development and progression. METHODS: We examined the top 20 highly expressed piRNAs based on the analysis of TCGA breast cancer data in two patient cohorts to test the roles of piRNAs in breast cancer. The effects of piRNA-36,712 on the malignant phenotypes and chemosensitivity of breast cancer cells were detected in vitro and in vivo. MS2-RIP and reporter gene assays were conducted to identify the interaction and regulation among piRNA-36,712, miRNAs and SEPW1P. Kaplan-Meier estimate with log-rank test was used to compare patient survival by different piRNA-36,712 expression levels. RESULTS: We found piRNA-36,712 level was significantly lower in breast cancer than in normal breast tissues and low level was correlated with poor clinical outcome in patients. Functional studies demonstrated that piRNA-36,712 interacts with RNAs produced by SEPW1P, a retroprocessed pseudogene of SEPW1, and subsequently inhibits SEPW1 expression through competition of SEPW1 mRNA with SEPW1P RNA for microRNA-7 and microRNA-324. We also found that higher SEPW1 expression due to downregulation of piRNA-36,712 in breast cancer may suppress P53, leading to the upregulated Slug but decreased P21 and E-cadherin levels, thus promoting cancer cell proliferation, invasion and migration. Furthermore, we found that piRNA-36,712 had synergistic anticancer effects with the paclitaxel and doxorubicin, two chemotherapeutic agents for breast cancer. CONCLUSIONS: These findings suggest that piRNA-36,712 is a novel tumor suppressor and may serve as a potential predictor for the prognosis of breast cancer patients.

Evaluation of menopausal status among breast cancer patients with chemotherapy-induced amenorrhea.

OBJECTIVE: In patients with chemotherapy-induced amenorrhea (CIA), the menopausal status is ambiguous and difficult to evaluate. This study aimed to establish a discriminative model to predict and classify the menopausal status of breast cancer patients with CIA. METHODS: This is a single center hospital-based study from 2013 to 2016. The menopausal age distribution and accumulated incidence rate of CIA are described. Multivariate models were adjusted for established and potential confounding factors including age, serum concentration of estradiol (E2) and follicle-stimulating hormone (FSH), feeding, pregnancy, parity, abortions, and body mass index (BMI). The odds ratio (OR) and 95% confidence interval (95% CI) of different risk factors were estimated. RESULTS: A total of 1,796 breast cancer patients were included in this study, among whom, 1,175 (65.42%) were premenopausal patients and 621 (34.58%) were post-menopause patients. Five hundred and fifty patients were included in CIA analysis, and a cumulative CIA rate of 81.64% was found in them. Age (OR: 1.856, 95% CI: 1.732-1.990), serum concentration of E2 (OR: 0.976, 95% CI: 0.972-0.980) and FSH (OR: 1.060, 95% CI: 1.053-1.066), and menarche age (OR: 1.074, 95% CI: 1.009-1.144) were found to be associated with the patients' menopausal status. According to multivariate analysis, the discriminative model to predict the menopausal status is Logit (P)=-28.396+0.536Age-0.014E2+0.031FSH. The sensitivities for this model were higher than 85%, and its specificities were higher than 89%. CONCLUSIONS: The discriminative model obtained from this study for predicting menstrual state is important for premenopausal patients with CIA. This model has high specificity and sensitivity and should be prudently used.

Identification of the endosomal sorting complex required for transport-I (ESCRT-I) as an important modulator of anti-miR uptake by cancer cells.

Mechanisms of unassisted delivery of RNA therapeutics, including inhibitors of microRNAs, remain poorly understood. We observed that the hepatocellular carcinoma cell line SKHEP1 retains productive free uptake of a miR-21 inhibitor (anti-miR-21). Uptake of anti-miR-21, but not a mismatch (MM) control, induces expression of known miR-21 targets (DDAH1, ANKRD46) and leads to dose-dependent inhibition of cell growth. To elucidate mechanisms of SKHEP1 sensitivity to anti-miR-21, we conducted an unbiased shRNA screen that revealed tumor susceptibility gene 101 (TSG101), a component of the endosomal sorting complex required for transport (ESCRT-I), as an important determinant of anti-proliferative effects of anti-miR-21. RNA interference-mediated knockdown of TSG101 and another ESCRT-I protein, VPS28, improved uptake of anti-miR-21 in parental SKHEP1 cells and restored productive uptake to SKHEP1 clones with acquired resistance to anti-miR-21. Depletion of ESCRT-I in several additional cancer cell lines with inherently poor uptake resulted in improved activity of anti-miR-21. Finally, knockdown of TSG101 increased uptake of anti-miR-21 by cancer cells in vivo following systemic delivery. Collectively, these data support an important role for the ESCRT-I complex in the regulation of productive free uptake of anti-miRs and reveal potential avenues for improving oligonucleotide free uptake by cancer cells.

Selective inhibition of mutant isocitrate dehydrogenase 1 (IDH1) via disruption of a metal binding network by an allosteric small molecule.

Cancer-associated point mutations in isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) confer a neomorphic enzymatic activity: the reduction of α-ketoglutarate to d-2-hydroxyglutaric acid, which is proposed to act as an oncogenic metabolite by inducing hypermethylation of histones and DNA. Although selective inhibitors of mutant IDH1 and IDH2 have been identified and are currently under investigation as potential cancer therapeutics, the mechanistic basis for their selectivity is not yet well understood. A high throughput screen for selective inhibitors of IDH1 bearing the oncogenic mutation R132H identified compound 1, a bis-imidazole phenol that inhibits d-2-hydroxyglutaric acid production in cells. We investigated the mode of inhibition of compound 1 and a previously published IDH1 mutant inhibitor with a different chemical scaffold. Steady-state kinetics and biophysical studies show that both of these compounds selectively inhibit mutant IDH1 by binding to an allosteric site and that inhibition is competitive with respect to Mg(2+). A crystal structure of compound 1 complexed with R132H IDH1 indicates that the inhibitor binds at the dimer interface and makes direct contact with a residue involved in binding of the catalytically essential divalent cation. These results show that targeting a divalent cation binding residue can enable selective inhibition of mutant IDH1 and suggest that differences in magnesium binding between wild-type and mutant enzymes may contribute to the inhibitors' selectivity for the mutant enzyme.

Study of the Interactions of Fusarium virguliforme Toxin FvTox1 with Synthetic Peptides by Molecular Simulations and a Label-Free Biosensor.

Fusarium virguliforme is a soil borne pathogen that causes sudden death syndrome (SDS) in soybean plants. This pathogenic disease may result in severe soybean yield suppression and can cause serious economic harm. It has been shown that the FvTox1 toxin produced by the pathogen may be the root cause of foliar SDS. Anti-FvTox1 single-chain variable fragment antibody expressed in transgenic soybean plants was shown to neutralize the FvTox1 toxin involved in foliar SDS development. Here, we have investigated the binding affinities of FvTox1 with four FvTox1-interacting peptides of 7 to 12 amino acids identified from phage display libraries using both bioinformatics-based molecular simulations and label-free bioassays with a unique photonic crystal biosensor. Results from the molecular simulations have predicted the interaction energies and 3-dimensional (3D) structures of FvTox1 and FvTox1-interacting peptide complexes. Our label-free binding assays have further provided the interaction strength of FvTox1 with four different FvTox1-interacting peptides and experimentally confirmed the simulation results obtained from bioinformatics-based molecular calculations.

PIM inhibitors target CD25-positive AML cells through concomitant suppression of STAT5 activation and degradation of MYC oncogene.

Postchemotherapy relapse presents a major unmet medical need in acute myeloid leukemia (AML), where treatment options are limited. CD25 is a leukemic stem cell marker and a conspicuous prognostic marker for overall/relapse-free survival in AML. Rare occurrence of genetic alterations among PIM family members imposes a substantial hurdle in formulating a compelling patient stratification strategy for the clinical development of selective PIM inhibitors in cancer. Here we show that CD25, a bona fide STAT5 regulated gene, is a mechanistically relevant predictive biomarker for sensitivity to PIM kinase inhibitors. Alone or in combination with tyrosine kinase inhibitors, PIM inhibitors can suppress STAT5 activation and significantly shorten the half-life of MYC to achieve substantial growth inhibition of high CD25-expressing AML cells. Our results highlight the importance of STAT5 and MYC in rendering cancer cells sensitive to PIM inhibitors. Because the presence of a CD25-positive subpopulation in leukemic blasts correlates with poor overall or relapse-free survival, our data suggest that a combination of PIM inhibitors with chemotherapy and tyrosine kinase inhibitors could improve long-term therapeutic outcomes in CD25-positive AML.

Complete inactivation of DNMT1 leads to mitotic catastrophe in human cancer cells.

Studies have shown that DNA (cytosine-5-)-methyltransferase 1 (DNMT1) is the principal enzyme responsible for maintaining CpG methylation and is required for embryonic development and survival of somatic cells in mice. The role of DNMT1 in human cancer cells, however, remains highly controversial. Using homologous recombination, here we have generated a DNMT1 conditional allele in the human colorectal carcinoma cell line HCT116 in which several exons encoding the catalytic domain are flanked by loxP sites. Cre recombinase-mediated disruption of this allele results in hemimethylation of approximately 20% of CpG-CpG dyads in the genome, coupled with activation of the G2/M checkpoint, leading to arrest in the G2 phase of the cell cycle. Although cells gradually escape from this arrest, they show severe mitotic defects and undergo cell death either during mitosis or after arresting in a tetraploid G1 state. Our results thus show that DNMT1 is required for faithfully maintaining DNA methylation patterns in human cancer cells and is essential for their proliferation and survival.

Breast Cancer Disparities: A Multicenter Comparison of Tumor Diagnosis, Characteristics, and Surgical Treatment in China and the U.S.

BACKGROUND AND OBJECTIVE: Incidence of and mortality rates for breast cancer continue to rise in the People's Republic of China. The purpose of this study was to analyze differences in characteristics of breast malignancies between China and the U.S. METHODS: Data from 384,262 breast cancer patients registered in the U.S. Surveillance, Epidemiology, and End Results (SEER) program from 2000 to 2010 were compared with 4,211 Chinese breast cancer patients registered in a Chinese database from 1999 to 2008. Outcomes included age, race, histology, tumor and node staging, laterality, surgical treatment method, and reconstruction. The Pearson chi-square and Fisher's exact tests were used to compare rates. RESULTS: Infiltrating ductal carcinoma was the most common type of malignancy in the U.S. and China. The mean number of positive lymph nodes was higher in China (2.59 vs. 1.31, p < .001). Stage at diagnosis was higher in China (stage IIA vs. I, p < .001). Mean size of tumor at diagnosis was higher in China (32.63 vs. 21.57 mm). Mean age at diagnosis was lower in China (48.28 vs. 61.29 years, p < .001). Moreover, 2.0% of U.S. women underwent radical mastectomy compared with 12.5% in China, and 0.02% in China underwent reconstructive surgery. CONCLUSION: Chinese women were diagnosed at younger ages with higher stage and larger tumors and underwent more aggressive surgical treatment. Prospective trials should be conducted to address screening, surgical, and tumor discrepancies between China and the U.S. IMPLICATIONS FOR PRACTICE: Breast cancer patients in China are diagnosed at later stages than those in America, which might contribute to different clinical management and lower 5-year survival rate. This phenomenon suggests that an earlier detection and treatment program should be widely implemented in China. By comparing the characteristics of Chinese and Chinese-American patients, we found significant differences in tumor size, lymph nodes metastasis, and age at diagnosis. These consequences indicated that patients with similar genetic backgrounds may have different prognoses due to the influence of environment and social economic determinates.