Han-Byoel Lee

Single-cell RNA-seq enables comprehensive tumour and immune cell profiling in primary breast cancer

Single-cell transcriptome profiling of tumour tissue isolates allows the characterization of heterogeneous tumour cells along with neighbouring stromal and immune cells. Here we adopt this powerful approach to breast cancer and analyse 515 cells from 11 patients. Inferred copy number variations from the single-cell RNA-seq data separate carcinoma cells from non-cancer cells. At a single-cell resolution, carcinoma cells display common signatures within the tumour as well as intratumoral heterogeneity regarding breast cancer subtype and crucial cancer-related pathways. Most of the non-cancer cells are immune cells, with three distinct clusters of T lymphocytes, B lymphocytes and macrophages. T lymphocytes and macrophages both display immunosuppressive characteristics: T cells with a regulatory or an exhausted phenotype and macrophages with an M2 phenotype. These results illustrate that the breast cancer transcriptome has a wide range of intratumoral heterogeneity, which is shaped by the tumour cells and immune cells in the surrounding microenvironment.

Unique Features of Young Age Breast Cancer and Its Management

Young age breast cancer (YABC) has unique clinical and biological features that are not seen in older patients. Breast tumor biology is more aggressive and is associated with an unfavorable prognosis in younger women. The diagnosis of breast cancer is often delayed, resulting in their initial presentation with more advanced disease. Together, these characteristics lead to a poorer prognosis in younger women than in older women. Young women who receive breast-conserving therapy have a higher rate of local recurrence. Therefore, it is important to secure sufficient resection margins and consider boost radiotherapy to prevent local treatment failure. Based on age alone, patients with YABC should be regarded as high-risk cases, and they should be treated with adjuvant chemotherapy. Special considerations regarding psychosocial factors and fertility should be taken into account for young patients. This review discusses the major considerations and principles concerning the management of patients with YABC.

Predictive Significance of p53, Ki-67, and Bcl-2 Expression for Pathologic Complete Response after Neoadjuvant Chemotherapy for Triple-Negative Breast Cancer

Purpose Patients with triple-negative breast cancer (TNBC) with pathologic complete response (pCR) to neoadjuvant chemotherapy (NAC) have superior survival outcomes compared to those with residual disease after NAC. This study investigated the value of three biomarkers, p53, Ki-67, and Bcl-2 for predicting pCR in NAC-treated patients with TNBC. Methods Between 2003 and 2012, 198 patients with pathologically confirmed primary TNBC were treated with two different taxane-based chemotherapeutic regimens prior to surgery. Before NAC, expression of p53 (cutoff 25%), Ki-67 (cutoff 10%), and Bcl-2 (cutoff 10%) was assessed immunohistochemically in core biopsy specimens. The incidence of pCR was correlated with the expression of these biomarkers. Results Overall, pCR occurred in 37 of the 198 patients (18.7%). A significant association was observed between the pCR rate and overexpression of the p53 and Ki-67 biomarkers. Multivariate analysis showed that only p53 expression was independently associated with pCR to NAC (odds ratio, 3.961; p=0.003). The sensitivity, specificity, positive predictive value, and negative predictive value of p53 expression for predicting pCR were 77.8%, 50.3%, 26.2%, and 90.9%, respectively. The pCR rate was the lowest (5.2%) in patients with low expression of both p53 and Ki-67, and it was the highest (25.8%) when both biomarkers showed high expression. Conclusion Expression of p53 was significantly associated with pCR after NAC in patients with TNBC, suggesting that this biomarker might be particularly valuable in identifying TNBC patients prone to have residual disease after NAC.

Oncologic Safety of Immediate Breast Reconstruction for Invasive Breast Cancer Patients: A Matched Case Control Study

Purpose The purpose of this study was to compare locoregional recurrence-free survival (LRFS) and disease-free survival (DFS) between patients undergoing mastectomy and immediate breast reconstruction (IBR) and those undergoing mastectomy alone. Methods A retrospective review of patients who underwent mastectomy and immediate breast reconstruction for resectable invasive breast cancer between 2002 and 2010 at a single center was conducted. These cases were matched to patients who underwent mastectomy alone in the same time period, performed by 1:2 matching. Matching control variables included age, tumor size, axillary lymph node metastasis, and estrogen receptor status. Overall, 189 patients were identified in the IBR group, and 362 patients were matched to this group. Results In the IBR group, 75 patients (39.7%) underwent conventional total mastectomy, 78 (41.3%) underwent skin-sparing mastectomy (SSM), and 36 (19.0%) underwent nipple-sparing mastectomy (NSM). The IBR group was significantly younger than the control group (41.9 and 45.1 years, respectively) (p=0.032), in spite of matching between three age groups. The DFS rates were similar between the IBR group and mastectomy alone group, at 92.0% and 89.9%, respectively, at 5-year follow-up (log-rank test, p=0.496). The 5-year LRFS was 96.2% in the IBR group and 96.4% in the mastectomy alone group (log-rank test, p=0.704), similar to data from previous reports. Subgroup analyses for SSM or NSM patients showed no differences in LRFS and DFS between the two groups. Additionally, in stage III patients, IBR did not cause an increase in recurrence. Conclusion IBR after mastectomy, including both SSM and NSM, had no negative impact on recurrence or patient survival, even in patients with advanced disease.

The use of FNA samples for whole‐exome sequencing and detection of somatic mutations in breast cancer surgical specimens

The availability of suitable biospecimens is critical to the success of advanced genomic analyses. The objective of this study was to assess the sensitivity of fine‐needle aspiration (FNA) compared with gross surgical sampling (GSS) from surgical specimens for the detection of somatic mutations in breast cancer using whole‐exome sequencing (WES).

Transition into inflammatory cancer-associated adipocytes in breast cancer microenvironment requires microRNA regulatory mechanism

The role of adipocytes in cancer microenvironment has gained focus during the recent years. However, the characteristics of the cancer-associated adipocytes (CAA) in human breast cancer tissues and the underlying regulatory mechanism are not clearly understood. We reviewed pathology specimens of breast cancer patients to understand the morphologic characteristics of CAA, and profiled the mRNA and miRNA expression of CAA by using indirect co-culture system in vitro. The CAAs in human breast cancers showed heterogeneous topographic relationship with breast cancer cells within the breast microenvironment. The CAAs exhibited the characteristics of de-differentiation determined by their microscopic appearance and the expression levels of adipogenic markers. Additionally, the 3T3-L1 adipocytes indirectly co-cultured with breast cancer cells showed up-regulation of inflammation-related genes including Il6 and Ptx3. The up-regulation of IL6 in CAA was further observed in human breast cancer tissues. miRNA array of indirectly co-cultured 3T3-L1 cells showed increased expression of mmu-miR-5112 which may target Cpeb1. Cpeb1 is a negative regulator of Il6. The suppressive role of mmu-miR-5112 was confirmed by dual luciferase reporter assay, and mmu-miR-5112-treated adipocytes showed up-regulation of Il6. The transition of adipocytes into more inflammatory CAA resulted in proliferation-promoting effect in ER positive breast cancer cells such as MCF7 and ZR-75-1 but not in ER negative cells. In this study, we have determined the de-differentiated and inflammatory natures of CAA in breast cancer microenvironment. Additionally, we propose a miRNA-based regulatory mechanism underlying the process of acquiring inflammatory phenotypes in CAA.

In Vivo Tumor Growth Rate Measured by US in Preoperative Period and Long Term Disease Outcome in Breast Cancer Patients

Objective The aim of our study was to evaluate the effect of tumor growth rate, calculated from tumor size measurements by US, on breast cancer patients’ outcome. Patients and Methods Breast cancer patients who received at least two serial breast ultrasonographies (US) in our institution during preoperative period and were surgically treated between 2002 and 2010 were reviewed. Tumor growth rate was determined by specific growth rate (SGR) using the two time point tumor sizes by US. Results A total of 957 patients were analyzed. The median duration between initial and second US was 28 days (range, 8–140). The median initial tumor size was 1.7cm (range, 0.4–7.0) and median second size was 1.9cm (range, 0.3–7.2). 523(54.6%) cases had increase in size. The median SGR(x10-2) was 0.59 (range, -11.90~31.49) and mean tumor doubling time was 14.51 days. Tumor growth rate was higher when initial tumor size was smaller. Lymphovascular invasion, axillary lymph node metastasis, and higher histologic grade were significantly associated with higher SGR. SGR was significantly associated with disease-free survival (DFS) in a univariate analysis (p = 0.04), but not in a multivariate Cox analysis (p>0.05). High SGR was significantly associated with worse DFS in a subgroup of initial tumor size >2cm (p = 0.018), but not in those with tumor size <2cm (p>0.05). Conclusion Our results showed that tumor growth rate measured by US in a relatively short time interval was associated with other worse prognostic factors and DFS, but it was not an independent prognostic factor in breast cancer patients.

Can We Skip Intraoperative Evaluation of Sentinel Lymph Nodes? Nomogram Predicting Involvement of Three or More Axillary Lymph Nodes before Breast Cancer Surgery

Purpose The American College of Surgeons Oncology Group Z0011 trial reported that complete dissection of axillary lymph nodes (ALNs) may not be warranted in women with clinical T1-T2 tumors and one or two involved ALNs who were undergoing lumpectomy plus radiation followed by systemic therapy. The present study was conducted to identify preoperative imaging predictors of ≥ 3 ALNs. Materials and Methods The training set consisted of 1,917 patients with clinical T1-T2 and node negative invasive breast cancer. Factors associated with ≥ 3 involved ALNs were evaluated by logistic regression analysis. The validation set consisted of 378 independent patients. The nomogram was applied prospectively to 512 patients who met the Z0011 criteria. Results Of the 1,917 patients, 204 (10.6%) had ≥ 3 positive nodes. Multivariate analysis showed that involvement of ≥ 3 nodes was significantly associated with ultrasonographic and chest computed tomography findings of suspicious ALNs (p < 0.001 each). These two imaging criteria, plus patient age, were used to develop a nomogram calculating the probability of involvement of ≥ 3 ALNs. The areas under the receiver operating characteristic curve of the nomogram were 0.852 (95% confidence interval [CI], 0.820 to 0.883) for the training set and 0.896 (95% CI, 0.836 to 0.957) for the validation set. Prospective application of the nomogram showed that 60 of 512 patients (11.7%) had scores above the cut-off. Application of the nomogram reduced operation time and cost, with a very low re-operation rate (1.6%). Conclusion Patients likely to have ≥ 3 positive ALNs could be identified by preoperative imaging. The nomogram was helpful in selective intraoperative examination of sentinel lymph nodes.

The Clinical Significance and Molecular Features of the Spatial Tumor Shapes in Breast Cancers

Each breast cancer has its unique spatial shape, but the clinical importance and the underlying mechanism for the three-dimensional tumor shapes are mostly unknown. We collected the data on the three-dimensional tumor size and tumor volume data of invasive breast cancers from 2,250 patients who underwent surgery between Jan 2000 and Jul 2007. The degree of tumor eccentricity was estimated by using the difference between the spheroid tumor volume and ellipsoid tumor volume (spheroid-ellipsoid discrepancy, SED). In 41 patients, transcriptome and exome sequencing data obtained. Estimation of more accurate tumor burden by calculating ellipsoid tumor volumes did not improve the outcome prediction when compared to the traditional longest diameter measurement. However, the spatial tumor eccentricity, which was measured by SED, showed significant variation between the molecular subtypes of breast cancer. Additionally, the degree of tumor eccentricity was associated with well-known prognostic factors of breast cancer such as tumor size and lymph node metastasis. Transcriptome data from 41 patients showed significant association between MMP13 and spatial tumor shapes. Network analysis and analysis of TCGA gene expression data suggest that MMP13 is regulated by ERBB2 and S100A7A. The present study validates the usefulness of the current tumor size method in determining tumor stages. Furthermore, we show that the tumors with high eccentricity are more likely to have aggressive tumor characteristics. Genes involved in the extracellular matrix remodeling can be candidate regulators of the spatial tumor shapes in breast cancer.

S100A8/A9 mediate the reprograming of normal mammary epithelial cells induced by dynamic cell-cell interactions with adjacent breast cancer cells.

To understand the potential effects of cancer cells on surrounding normal mammary epithelial cells, we performed direct co-culture of non-tumorigenic mammary epithelial MCF10A cells and various breast cancer cells. Firstly, we observed dynamic cell-cell interactions between the MCF10A cells and breast cancer cells including lamellipodia or nanotube-like contacts and transfer of extracellular vesicles. Co-cultured MCF10A cells exhibited features of epithelial-mesenchymal transition, and showed increased capacity of cell proliferation, migration, colony formation, and 3-dimensional sphere formation. Transcriptome analysis and phosphor-protein array suggested that several cancer-related pathways are significantly dysregulated in MCF10A cells after the direct co-culture with breast cancer cells. S100A8 and S100A9 showed distinct up-regulation in the co-cultured MCF10A cells and their microenvironmental upregulation was also observed in the orthotropic xenograft of syngeneic mouse mammary tumors. When S100A8/A9 overexpression was induced in MCF10A cells, the cells showed phenotypic features of directly co-cultured MCF10A cells in terms of in vitro cell behaviors and signaling activities suggesting a S100A8/A9-mediated transition program in non-tumorigenic epithelial cells. This study suggests the possibility of dynamic cell-cell interactions between non-tumorigenic mammary epithelial cells and breast cancer cells that could lead to a substantial transition in molecular and functional characteristics of mammary epithelial cells.