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 materialThe online version of this article (doi:10.1007/s00262-017-1977-z) contains supplementary material, which is available to authorized users.

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.

Despite major advances in early detection and prognosis, chemotherapy resistance is a major hurdle in the battle against breast cancer. Identifying predictive markers and understanding the mechanisms are key steps to overcoming chemoresistance. Methylation-controlled J protein (MCJ, also known as DNAJC15) is a negative regulator of mitochondrial respiration and has been associated with chemotherapeutic drug sensitivity in cancer cell lines. Here we show, in a retrospective study of a large cohort of breast cancer patients, that low MCJ expression in breast tumors predicts high risk of relapse in patients treated with chemotherapy; however, MCJ expression does not correlate with response to endocrine therapy. In a prospective study in breast cancer patients undergoing neoadjuvant therapy, low MCJ expression also correlates with poor clinical response to chemotherapy and decreased disease-free survival. Using MCJ-deficient mice, we demonstrate that lack of MCJ is sufficient to induce mammary tumor chemoresistance in vivo. Thus, loss of expression of this endogenous mitochondrial modulator in breast cancer promotes the development of chemoresistance.

Stereotactic core needle biopsy has proven to be an accurate technique for evaluation of mammographically detected microcalcification. The development of the Mammotome biopsy system has led many medical centers to use this vacuum-assisted device for the sampling of microcalcifications in mammographically detected nonpalpable breast lesions. Ninety-six women underwent 101 stereotactic Mammotome core biopsies for mammographic calcifications over a 32-month period in the Department of Surgery at Tawam Hospital, the national referral oncology center in the UAE. The stereotactic procedure was performed by surgeons using the Mammotome biopsy system. Microcalcifications were evident on specimen radiographs and microscopic sections in 96% and 87% of the cases, respectively. Excisional biopsy was recommended for diagnoses of atypical ductal hyperplasia or carcinoma. Patients with benign diagnoses underwent mammographic follow-up. Eighty-one lesions were benign, 5 atypical ductal hyperplasias and 14 carcinomas were diagnosed (2 invasive lobular carcinoma, 4 invasive ductal carcinoma, and 8 intraductal carcinomas in situ: 1 comedo, 1 cribriform, 6 mixed cribriform and micropapillary). Surgical excision in four patients with atypia on Mammotome biopsy (one was lost to follow-up) showed atypical ductal hyperplasia. Surgical excision in seven patients diagnosed with intraductal carcinoma in situ (one patient lost to follow-up) showed intraductal carcinoma with no evidence of microinvasion. Similar diagnoses were made in all the invasive ductal and lobular carcinomas in both Mammotome and excisional biopsies. A diagnosis of atypia on Mammotome biopsy warranted excision of the atypical area, yet the underestimation rate for the presence of carcinoma remained low. The likelihood of an invasive component at excision was negligible for microcalcification diagnosed as intraductal carcinoma in situ on Mammotome biopsy. Mammotome biopsy proved to be an accurate technique for the sampling, diagnosis, and early detection of breast cancer.