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Mohd Saleem,1 Azharuddin Sajid Syed Khaja,1 Ashfaque Hossain,2 Fahaad Alenazi,3 Kamaleldin B Said,1 Soha Abdallah Moursi,1 Homoud Abdulmohsin Almalaq,4 Hamza Mohamed,5 Ehab Rakha,6,7 Mohammed Salem Alharbi,8 Salma Ahmed Ali Babiker,9 Kauser Usman10 1Department of Pathology, College of Medicine, University of Hail, Hail, Kingdom of Saudi Arabia; 2Department of Medical Microbiology and Immunology, RAK Medical and Health Sciences University, Ras Al Khaimah, United Arab Emirates; 3Department of Pharmacology, College of Medicine, University of Hail, Hail, Kingdom of Saudi Arabia; 4Hail Health Cluster, King Khalid Hospital, College of Pharmacy, King Saud University, Riyadh, Kingdom of Saudi Arabia; 5Anatomy Department, Faculty of Medicine, Northern Border University, Arar, Kingdom of Saudi Arabia; 6Laboratory Department, King Khalid Hospital, Hail, Kingdom of Saudi Arabia; 7Clinical Pathology Department, Faculty of Medicine, Mansoura University, Mansoura, Egypt; 8Department of Internal Medicine, College of Medicine, University of Hail, Hail, Kingdom of Saudi Arabia; 9Department of Family Medicine, Hail University Medical Clinics, University of Hail, Hail, Kingdom of Saudi Arabia; 10Department of Internal Medicine, King George’s Medical University, Lucknow, IndiaCorrespondence: Azharuddin Sajid Syed Khaja, Department of Pathology, College of Medicine, University of Hail, Hail, Kingdom of Saudi Arabia, Tel +966 59 184 9573, Email skazharuddin@uoh.edu.saPurpose: Ventilator-associated pneumonia (VAP) is associated with a higher mortality risk for critical patients in the intensive care unit (ICU). Several strategies, including using β-lactam antibiotics, have been employed to prevent VAP in the ICU. However, the lack of a gold-standard method for VAP diagnosis and a rise in antibiotic-resistant microorganisms have posed challenges in managing VAP. The present study is designed to identify, characterize, and perform antimicrobial susceptibility of the microorganisms from different clinical types of infections in ICU patients with emphasis on VAP patients to understand the frequency of the latter, among others.Patients and Methods: A 1-year prospective study was carried out on patients in the ICU unit at a tertiary care hospital, Hail, Saudi Arabia.Results: A total of 591 clinically suspected hospital-acquired infections (HAI) were investigated, and a total of 163 bacterial isolates were obtained from different clinical specimens with a high proportion of bacteria found associated with VAP (70, 43%), followed by CAUTI (39, 24%), CLABSI (25, 15%), and SSI (14, 8.6%). Klebsiella pneumoniae was the most common isolate 39 (24%), followed by Acinetobacter baumannii 35 (21.5%), Pseudomonas aeruginosa 25 (15.3%), and Proteus spp 23 (14%). Among the highly prevalent bacterial isolates, extended-spectrum beta-lactamase was predominant 42 (42.4%).Conclusion: Proper use of antibiotics, continuous monitoring of drug sensitivity patterns, and taking all precautionary measures to prevent beta-lactamase-producing organisms in clinical settings are crucial and significant factors in fending off life-threatening infections for a better outcome.Keywords: ICU, VAP, ESBL, Klebsiella pneumoniae, Acinetobacter baumannii

Aim: Coronavirus infection has caused disease at the pandemic level with several deaths worldwide and affected all aspects of human life. One way to minimize virus transmission and its effects is to perform mass vaccination within the general population so that herd immunity is developed against the SARS-CoV-2 virus. However, low health literacy and vaccine hesitancy are potential threats in achieving this. The present study is designed to measure the Knowledge, Attitude, and Perception levels towards COVID-19 and assess public perception and acceptance levels of the vaccine among the general population in the Hail province of Saudi Arabia. Methods: A bilingual, community-based questionnaire, consisting of the respondents’ socio-demographic profile, COVID-19 knowledge, and attitude & perception towards COVID-19 vaccination, was circulated using different social media platforms. The collected data was analyzed using SPSS software. Results: Appropriate knowledge level was found in 74.8% of the respondents, whereas inappropriate knowledge levels were observed in females and participants with non-health-related occupations and were inversely related to willingness to the vaccine. More than 60% of the respondents had a negative attitude towards the COVID-19 vaccine, as only 51% were willing to get vaccinated. A negative attitude was significantly associated with female respondents. Conclusion: Our study reports a high knowledge level among the respondents in the Hail province. However, there is also a decreased willingness to be vaccinated, suggesting that more vaccine and health literacy seminars should be conducted to generate awareness among the general population in the Hail province, KSA.

A 1-year prospective study was carried out on patients in the ICU unit at a tertiary care hospital, Hail, Kingdom of Saudi Arabia. A total of 163 bacterial isolates were obtained from different clinical specimens with a high proportion of bacteria found associated with ventilator-associated pneumoniae (70, 43%), followed by catheter-associated urinary tract infection (39, 24%), central line-associated bloodstream infection (25, 15%), and surgical site infection (14, 8.6%). Klebsiella pneumoniae was the most common isolate (39, 24%), followed by Acinetobacter baumannii (35, 21.47%), Pseudomonas aeruginosa (25, 15%), and Proteus spp (23, 14%). Among the highly prevalent bacterial isolates, extended-spectrum beta-lactamase was predominant (42, 42.4%). Proper use of antibiotics, continuous monitoring of drug sensitivity patterns, and taking all precautionary measures to prevent beta-lactamases-producing organisms in the clinical settings are crucial and significant factors to fend off life-threatening infections and for a better outcome.

A 2-year prospective study carried out on ventilator-associated pneumonia (VAP) patients in the intensive care unit at a tertiary care hospital, Hail, Kingdom of Saudi Arabia (KSA), revealed a high prevalence of extremely drug-resistant (XDR)

A 2-year prospective study carried out on ventilator-associated pneumonia (VAP) patients in the intensive care unit at a tertiary care hospital, Hail, Kingdom of Saudi Arabia (KSA), revealed a high prevalence of extremely drug-resistant (XDR) Acinetobacter baumannii. About a 9% increase in the incidence rate of A. baumannii occurred in the VAP patients between 2019 and 2020 (21.4% to 30.7%). In 2019, the isolates were positive for IMP-1 and VIM-2 (31.1% and 25.7%, respectively) as detected by PCR. In comparison, a higher proportion of isolates produced NDM-1 in 2020. Here, we observed a high proportion of resistant ICU isolates towards the most common antibiotics in use. Colistin sensitivity dropped to 91.4% in the year 2020 as compared to 2019 (100%). Thus, the finding of this study has a highly significant clinical implementation in the clinical management strategies for VAP patients. Furthermore, strict implementation of antibiotic stewardship policies, regular surveillance programs for antimicrobial resistance monitoring, and screening for genes encoding drug resistance phenotypes have become imperative.

Objective: To evaluate the levels of information regarding the current emerging outbreak of coronavirus disease 2019 (COVID-19) among medical and dental students at universities in Saudi Arabia through an online questionnaire Methods: A detailed structured questionnaire was prepared, containing demographic profiles and questions related to knowledge and awareness of the COVID-19 pandemic, and was emailed to 240 subjects, out of these, 209 responded to all the questions Results: The majority of the respondents were aware of the current and past epidemics of the coronavirus diseases, and they heard about SARS or MERS (89 5%) and the COVID-19 pandemic (94 7%) Internet was the main source of information (63 1%) followed by professors and physicians (24 2%), print media (6 1%), television (4%), and family or friends (2 5%) The majority of respondents received information about COVID-19 from the Ministry of Health (85 6%) and 44 5% of respondents participated in the COVID-19 symposium or conference Respondents of the college of Medicine were more aware (96 1%) about COVID-19 than respondents of the college of Dentistry (86 2%;p=0 02) Conclusion: The study finds a high level of COVID-19 awareness among medical and dental students at KSA universities However, there is a need to study in a community-level assessment regarding knowledge about COVID-19 © 2020, Indian Association of Preventive and Social Medicine All rights reserved

In the present study, we unrevealed the effect of tamoxifen on ERα and PIP5K1α/AKT that are responsible for prostate cancer growth and invasion. Tamoxifen in combination treatment with PIP5K1α inhibitor, ISA‐2011B, led to tumor regression in xenograft mice. We found that depletion of tumor‐associated macrophages using clodronate sensitized the inhibitory effect of tamoxifen on prostate cancer., Selective ERα modulator, tamoxifen, is well tolerated in a heavily pretreated castration‐resistant prostate cancer (PCa) patient cohort. However, its targeted gene network and whether expression of intratumor ERα due to androgen deprivation therapy (ADT) may play a role in PCa progression is unknown. In this study, we examined the inhibitory effect of tamoxifen on castration‐resistant PCa in vitro and in vivo. We found that tamoxifen is a potent compound that induced a high degree of apoptosis and significantly suppressed growth of xenograft tumors in mice, at a degree comparable to ISA‐2011B, an inhibitor of PIP5K1α that acts upstream of PI3K/AKT survival signaling pathway. Moreover, depletion of tumor‐associated macrophages using clodronate in combination with tamoxifen increased inhibitory effect of tamoxifen on aggressive prostate tumors. We showed that both tamoxifen and ISA‐2011B exert their on‐target effects on prostate cancer cells by targeting cyclin D1 and PIP5K1α/AKT network and the interlinked estrogen signaling. Combination treatment using tamoxifen together with ISA‐2011B resulted in tumor regression and had superior inhibitory effect compared with that of tamoxifen or ISA‐2011B alone. We have identified sets of genes that are specifically targeted by tamoxifen, ISA‐2011B or combination of both agents by RNA‐seq. We discovered that alterations in unique gene signatures, in particular estrogen‐related marker genes are associated with poor patient disease‐free survival. We further showed that ERα interacted with PIP5K1α through formation of protein complexes in the nucleus, suggesting a functional link. Our finding is the first to suggest a new therapeutic potential to inhibit or utilize the mechanisms related to ERα, PIP5K1α/AKT network, and MMP9/VEGF signaling axis, providing a strategy to treat castration‐resistant ER‐positive subtype of prostate cancer tumors with metastatic potential.

Cancer cells facilitate growth and metastasis by using multiple signals from the cancer-associated microenvironment. However, it remains poorly understood whether prostate cancer (PCa) cells may recruit and utilize bone marrow cells for their growth and survival. Furthermore, the regulatory mechanisms underlying interactions between PCa cells and bone marrow cells are obscure. In this study, we isolated bone marrow cells that mainly constituted populations that were positive for CD11b and Gr1 antigens from xenograft PC-3 tumor tissues from athymic nu/nu mice. We found that the tumor-infiltrated cells alone were unable to form tumor spheroids, even with increased amounts and time. By contrast, the tumor-infiltrated cells together with PCa cells formed large numbers of tumor spheroids compared with PCa cells alone. We further utilized xenograft athymic nu/nu mice bearing bone metastatic lesions. We demonstrated that PCa cells were unable to survive and give rise to colony-forming units (CFUs) in media that were used for hematopoietic cell colony-formation unit (CFU) assays. By contrast, PC-3M cells survived when bone marrow cells were present and gave rise to CFUs. Our results showed that PCa cells required bone marrow cells to support their growth and survival and establish bone metastasis in the host environment. We showed that PCa cells that were treated with either siRNA for PIP5K1&alpha, or its specific inhibitor, ISA-2011B, were unable to survive and produce tumor spheroids, together with bone marrow cells. Given that the elevated expression of PIP5K1&alpha, was specific for PCa cells and was associated with the induced expression of VEGF receptor 2 in PCa cells, our findings suggest that cancer cells may utilize PIP5K1&alpha, mediated receptor signaling to recruit growth factors and ligands from the bone marrow-derived cells. Taken together, our study suggests a new mechanism that enables PCa cells to gain proliferative and invasive advantages within their associated host microenvironment. Therapeutic interventions using PIP5K1&alpha, inhibitors may not only inhibit tumor invasion and metastasis but also enhance the host immune system.

Currently, no effective targeted therapeutics exists for treatment of metastatic prostate cancer (PCa). Given that matrix metalloproteinases 9 (MMP9) and its associated vascular endothelial growth factor (VEGF) are critical for tumor vascularization and invasion under castration‐resistant condition, it is therefore of great importance to define the functional association and interplay between androgen receptor (AR) and MMP9 and their associated key survival and invasion pathways in PCa cells. Here, we found that there was a significant correlation between MMP9 and AR protein expression in primary and metastatic PCa tissues, and a trend that high level of MMP9 expression was associated with poor prognosis. We demonstrated that constitutive activation of AR increased expression of MMP9 and VEGF/VEGF receptors. We further showed that AR exerts its effect on MMP9/VEGF signaling axis through PIP5K1α/AKT. We showed that MMP9 physically interacted with PIP5K1α via formation of protein–protein complexes. Furthermore, elevated expression of MMP9 enhanced ability of AR to activate its target gene cyclin A1. The elevated sequential activation of AR/PIP5K1α/AKT/MMP9/VEGF signaling axis contributed to increased invasiveness and growth of metastatic tumors. Conversely, treatment with PIP5K1α inhibitor significantly suppressed invasiveness of PCa cells expressing constitutively activated AR, this was coincident with its inhibitory effect of this inhibitor on AR/MMP9/VEGF pathways. Our results suggest that AR and MMP9‐associated network proteins may be effectively targeted by blocking PIP5K1α/AKT pathways using PIP5K1α inhibitor in metastatic PCa., What's new? The androgen receptor (AR) is a key factor in prostate cancer (PCa) progression and metastasis. Given that matrix metalloproteinase 9 (MMP9) and the vascular endothelial growth factor (VEGF) pathway are critical for tumor vascularization and invasion under castration‐resistant condition, it may be of importance to define the functional interplay between AR and MMP9 and their associated key survival and invasion pathways in PCa cells. This study identifies novel cooperative mechanisms involving AR, the MMP9/ VEGF signaling axis and PIP5K1α/AKT pathways driving tumor invasion. The findings provide new information to guide the development of targeted therapy for invasive castration‐resistant prostate cancer.

Glutamate-ammonia ligase (GLUL) is important for acid-base homeostasis, ammonia detoxification, cell signaling, and proliferation. Here, we reported that GLUL ablation conferred resistance to several anticancer drugs in specific cancer cell lines while leaving other cell lines non-resistant to the same drugs. To understand the biochemical mechanics supporting this drug resistance, we compared drug-resistant GLUL knockout (KO) A549 non-small-cell lung carcinoma (NSCLC) cells with non-resistant GLUL KO H1299 NSCLC cells and found that the resistant A549 cells, to a larger extent, depended on exogenous glucose for proliferation. As GLUL activity is linked to the tricarboxylic acid (TCA) cycle via reversed glutaminolysis, we probed carbon flux through both glycolysis and TCA pathways by means of 13C5 glutamine, 13C5 glutamate, and 13C6 glucose tracing. We observed increased labeling of malate and aspartate in A549 GLUL KO cells, whereas the non-resistant GLUL KO H1299 cells displayed decreased 13C-labeling. The malate and aspartate shuttle supported cellular NADH production and was associated with cellular metabolic fitness. Inhibition of the malate-aspartate shuttle with aminooxyacetic acid significantly impacted upon cell viability with an IC50 of 11.5 &mu, M in resistant GLUL KO A549 cells compared to 28 &mu, M in control A549 cells, linking resistance to the malate-aspartate shuttle. Additionally, rescuing GLUL expression in A549 KO cells increased drug sensitivity. We proposed a novel metabolic mechanism in cancer drug resistance where the increased capacity of the malate-aspartate shuttle increased metabolic fitness, thereby facilitating cancer cells to escape drug pressure.

Despite recent improvement in adjuvant therapies, triple-negative, and ER+ subtypes of breast cancer (BC) with metastatic potentials remain the leading cause of BC-related deaths. We investigated the role of phosphatidylinositol-4-phosphate 5-kinase alpha (PIP5Kα), a key upstream factor of PI3K/AKT, and the therapeutic effect of PIP5Kα inhibitor on subtypes of BC. The clinical importance of PIP5K1α and its association with survivals were analyzed using three BC cohorts from Nottingham (n = 913), KM plotter (n = 112) and TCGA (n = 817). Targeted overexpression or knockdown of PIP5K1α were introduced into BC cell lines. The effects of PIP5K1α and its inhibitor on growth and invasion of BC were confirmed by using in vitro assays including proliferation, migration, apoptosis and luciferase reporter assays and in vivo xenograft mouse models. All statistical tests were two-sided. PIP5K1α was associated with poor patient outcome in triple-negative BC (for PIP5K1α protein, p = 0.011 and for mRNA expression, p = 0.028, log-rank test). 29% of triple-negative BC had PIP5K1A gene amplification. Elevated level of PIP5K1α increased expression of pSer-473 AKT (p < 0.001) and invasiveness of triple-negative MDA-MB-231 cells (p < 0.001). Conversely, inhibition of PIP5K1α using its inhibitor ISA-2011B, or via knockdown suppressed growth and invasiveness of MDA-MB-231 xenografts (mean vehicle-treated controls = 2160 mm3, and mean ISA-2011B-treated = 600 mm3, p < 0.001). ISA-2011B-treatment reduced expression of pSer-473 AKT (p < 0.001) and its downstream effectors including cyclin D1, VEGF and its receptors, VEGFR1 and VEGFR2 (p < 0.001) in xenograft tumors. In ER+ cancer cells, PIP5K1α acted on pSer-473 AKT, and was in complexes with VEGFR2, serving as co-factor of ER-alpha to regulate activities of target genes including cyclin D1 and CDK1. Our study suggests that our developed PIP5K1α inhibitor has a great potential on refining targeted therapeutics for treatment of triple-negative and ER+ BC with abnormal PI3K/AKT pathways.

// Azharuddin Sajid Syed Khaja 1, 2, * , Salman M. Toor 1, 2, * , Haytham El Salhat 3, 4 , Issam Faour 4 , Navid Ul Haq 5 , Bassam R. Ali 6 , Eyad Elkord 1, 2, 7 1 Cancer Research Center, Qatar Biomedical Research Institute, College of Science and Engineering, Hamad Bin Khalifa University, Qatar Foundation, Doha, Qatar 2 Department of Medical Microbiology and Immunology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates 3 Oncology Department, Al Noor Hospital, Abu Dhabi, United Arab Emirates 4 Surgery Department, Tawam Hospital, Al Ain, United Arab Emirates 5 Pathology Department, Tawam Hospital, Al Ain, United Arab Emirates 6 Department of Pathology, College of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates 7 Institute of Cancer Sciences, University of Manchester, Manchester, United Kingdom * These authors contributed equally to this work Correspondence to: Eyad Elkord, email: eelkord@hbku.edu.qa , eyad.elkord@manchester.ac.uk Keywords: regulatory T cells, FoxP3, helios, immune checkpoint receptors, primary breast cancer Received: February 21, 2017 Accepted: March 16, 2017 Published: March 25, 2017 ABSTRACT Immunosuppressive cells such as regulatory T cells (Tregs) have an ambiguous role in breast cancer prognosis, with studies reporting both positive and negative correlations between Treg infiltration and prognosis. This discrepancy could be due to the different immunosuppressive molecules present in these cells. In the present study, we phenotypically characterize different Treg subsets infiltrating the tumor microenvironment (TME), compared to adjacent normal tissue and peripheral blood of primary breast cancer (PBC) patients. We report that the majority of tumor-infiltrating CD4 + and CD8 + T cells have terminally exhaustive phenotype as assessed by CD39 and PD-1 expressions. We also show that Tregs are accumulated in breast TME compared to normal tissue. Further characterization of Tregs showed that these are mainly FoxP3 + Helios + and express high levels of CTLA-4 and PD-1. This preferential accumulation of FoxP3 + Helios + Treg subset with co-expression of different immune inhibitory molecules might have a negative effect on breast cancer prognosis. Taken together, our results suggest that breast tumor cells might utilize Tregs, and different suppressive pathways involving CD39, PD-1 and CTLA-4 molecules in creating an immune-subversive environment for them to survive, and a dual blockade of these immunosuppressive molecules might be considered as an effective method in breast cancer treatment.

Increased levels of myeloid cells, especially myeloid-derived suppressor cells (MDSCs), have been reported to correlate with bad prognosis and reduced survival in cancer patients. However, limited data are available on their conclusive phenotypes and their correlation with clinical settings. The aim of this study was to investigate levels and phenotype of myeloid cells in peripheral blood and tumor microenvironment (TME) of colorectal cancer (CRC) patients, compared to blood from healthy donors (HDs) and paired, adjacent non-tumor colon tissue. Flow cytometric analysis was performed to examine the expression of different myeloid markers in fresh peripheral blood samples from CRC patients and HDs, and tissue-infiltrating immune cells from CRC patients. We found significantly higher levels of cells expressing myeloid markers and lacking the expression of major histocompatibility complex class II molecule HLA-DR in blood and tumor of CRC patients. Further analysis revealed that these cells were granulocytic and expressed Arginase 1 indicative of their suppressive phenotype. These expanded cells could be neutrophils or granulocytic MDSCs, and we refer to them as granulocytic myeloid cells (GMCs) due to the phenotypical and functional overlap between these cell subsets. Interestingly, the expansion of peripheral GMCs correlated with higher stage and histological grade of cancer, thereby suggesting their role in cancer progression. Furthermore, an increase in CD33+CD11b+HLA-DR-CD14-CD15- immature myeloid cells was also observed in CRC tumor tissue. Our work shows that GMCs are expanded in circulation and TME of CRC patients, which provides further insights for developing immunotherapeutic approaches targeting these cell subsets to enhance antitumor immune and clinical responses.

Although Rac and its activator Tiam1 are known to stimulate cell-cell adhesion, the mechanisms regulating their activity in cell-cell junction formation are poorly understood. Here, we identify β2-syntrophin as a Tiam1 interactor required for optimal cell-cell adhesion. We show that during tight-junction (TJ) assembly β2-syntrophin promotes Tiam1-Rac activity, in contrast to the function of the apical determinant Par-3 whose inhibition of Tiam1-Rac activity is necessary for TJ assembly. We further demonstrate that β2-syntrophin localizes more basally than Par-3 at cell-cell junctions, thus generating an apicobasal Rac activity gradient at developing cell-cell junctions. Targeting active Rac to TJs shows that this gradient is required for optimal TJ assembly and apical lumen formation. Consistently, β2-syntrophin depletion perturbs Tiam1 and Rac localization at cell-cell junctions and causes defects in apical lumen formation. We conclude that β2-syntrophin and Par-3 fine-tune Rac activity along cell-cell junctions controlling TJ assembly and the establishment of apicobasal polarity.

Wnt5a, a member of non-canonical wingless-related MMTV integration site family is a secreted glycoprotein that plays important roles in development and disease. Recent studies have shown that Wnt5a protein levels are up-regulated in prostate cancer, but contrasting reports exist on the role of Wnt5a to predict outcome after radical prostatectomy in patients with localized prostate cancer. Our group has recently shown that preserved high protein expression of Wnt5a in prostate cancer is associated with longer relapse-free time after radical prostatectomy. The present tissue microarray study emphasizes the role of Wnt5a protein expression in a different, well-defined, and independent cohort consisting of 312 prostate cancer patients. Kaplan–Meier curves plotted between Wnt5a expression and time to biochemical recurrence revealed that in low-grade prostate cancer, patients with preserved high-Wnt5a protein levels in their tumor cells have a lower risk of recurrence after radical prostatectomy compared to patients with low-Wnt5a protein expression. When Wnt5a protein expression was added to a Cox regression multivariate analysis, both Wnt5a protein expression and surgical margin status independently predict biochemical free survival. Herein we confirm Wnt5a positivity as a prognostic factor and show that preserved overexpression of Wnt5a protein is associated with increased time to biochemical recurrence in localized low-grade prostate cancer patients after radical prostatectomy. Our results emphasize that Wnt5a can be used as a predictive biomarker, and favoring the view of Wnt5a as a future therapeutic target in prostate cancer patients with tumor cells displaying low expression of Wnt5a.

Background Wnt5a is a non-canonical secreted glycoprotein of the Wnt family that plays an important role in cancer development and progression. Previous studies report that Wnt5a is upregulated in prostate cancer and suggested that Wnt5a affects migration and invasion of prostate tumor cell. This study aimed to evaluate the prognostic value of Wnt5a protein expression in prostate cancer tissue and its potential to predict outcome after radical prostatectomy in patients with localized prostate cancer. Methodology and Results Immunohistochemical analysis of a tissue microarray containing prostate specimens of 503 patients with localized prostate cancer showed significantly higher Wnt5a protein expression in cancer compared to benign cores from the same patients (p

Pathological conditions including cancers lead to accumulation of a morphological mixture of highly immunosuppressive cells termed as myeloid-derived suppressor cells (MDSC). The lack of conclusive markers to identify human MDSC, due to their heterogeneous nature and close phenotypical and functional proximity with other cell subsets, made it challenging to identify these cells. Nevertheless, expansion of MDSC has been reported in periphery and tumor microenvironment of various cancers. The majority of studies on breast cancers were performed on murine models and hence limited literature is available on the relation of MDSC accumulation with clinical settings in breast cancer patients. The aim of this study was to investigate levels and phenotypes of myeloid cells in peripheral blood (n = 23) and tumor microenvironment of primary breast cancer patients (n = 7), compared with blood from healthy donors (n = 21) and paired non-tumor normal breast tissues from the same patients (n = 7). Using multicolor flow cytometric assays, we found that breast cancer patients had significantly higher levels of tumor-infiltrating myeloid cells, which comprised of granulocytes (P = 0.022) and immature cells that lack the expression of markers for fully differentiated monocytes or granulocytes (P = 0.016). Importantly, this expansion was not reflected in the peripheral blood. The immunosuppressive potential of these cells was confirmed by expression of Arginase 1 (ARG1), which is pivotal for T-cell suppression. These findings are important for developing therapeutic modalities to target mechanisms employed by immunosuppressive cells that generate an immune-permissive environment for the progression of cancer. Electronic supplementary material The online version of this article (doi:10.1007/s00262-017-1977-z) contains supplementary material, which is available to authorized users.