Gene Expression Profiling of Fibroepithelial Lesions of the Breast

Fibroepithelial Neoplasm with Hybrid Features of Benign Phyllodes Tumor, Juvenile Papillomatosis, and Juvenile Fibroadenoma: A Case Report

Phyllodes tumor is an uncommon breast fibroepithelial neoplasm mainly found in middle-aged patients, presenting a morphologic continuum from benign to malignant. Juvenile papillomatosis represents a rare benign proliferative breast tumor primarily affecting young individuals and carries a potential elevated risk of subsequent breast cancer development. Juvenile fibroadenoma is a well-circumscribed biphasic neoplasm that often occurs in adolescent girls, characterized by a pericanalicular growth pattern with usual-type epithelial hyperplasia and gynaecomastia-like micropapillary proliferation. Herein, we present an unusual example of a 26-year-old woman with a left breast outer lower quadrant palpable mass. Ultrasonography identified a 5.9 cm lobulated hypoechoic solid mass with scattered small cysts. The preoperative biopsy initially diagnosed a fibroepithelial lesion, considering giant cellular fibroadenoma and phyllodes tumor in the differential. Subsequent complete excision revealed areas of benign phyllodes tumor features closely admixed with distinctive elements such as prominent multiple cysts exhibiting apocrine and papillary apocrine metaplasia, duct papillomatosis, and duct stasis characteristic of juvenile papillomatosis, and hyperplastic ductal epithelium with micropapillary projections demonstrating a pericanalicular growth pattern indicative of juvenile fibroadenoma. The diagnosis was conclusively established as a fibroepithelial lesion with combined features of benign phyllodes tumor, juvenile papillomatosis, and juvenile fibroadenoma. Further investigation uncovered a family history of breast cancer. Molecular analysis revealed a pattern of unique and overlapping mutations within these distinct histopathological areas. This unusual presentation with hybrid features within a single tumor is described for the first time in the literature along with the molecular signature of the individual components.

Integrating single-cell and spatial transcriptomes reveals COL4A1/2 facilitates the spatial organisation of stromal cells differentiation in breast phyllodes tumours

BACKGROUND

Breast phyllodes tumours (PTs) are a unique type of fibroepithelial neoplasms with metastatic potential and recurrence tendency. However, the precise nature of heterogeneity in breast PTs remains poorly understood. This study aimed to elucidate the cell subpopulations composition and spatial structure and investigate diagnostic markers in the pathogenesis of PTs.

METHODS

We applied single-cell RNA sequencing and spatial transcriptomes on tumours and adjacent normal tissues for integration analysis. Immunofluorescence experiments were conducted to verify the tissue distribution of cells. Tumour cells from patients with PTs were cultured to validate the function of genes. To validate the heterogeneity, the epithelial and stromal components of tumour tissues were separated using laser capture microdissection, and microproteomics data were obtained using data-independent acquisition mass spectrometry. The diagnostic value of genes was assessed using immunohistochemistry staining.

RESULTS

Tumour stromal cells harboured seven subpopulations. Among them, a population of widely distributed cancer-associated fibroblast-like stroma cells exhibited strong communications with epithelial progenitors which underwent a mesenchymal transition. We identified two stromal subpopulations sharing epithelial progenitors and mesenchymal markers. They were inferred to further differentiate into transcriptionally active stromal subpopulations continuously expressing COL4A1/2. The binding of COL4A1/2 with ITGA1/B1 facilitated a growth pattern from the stroma towards the surrounding glands. Furthermore, we found consistent transcriptional changes between intratumoural heterogeneity and inter-patient heterogeneity by performing microproteomics studies on 30 samples from 11 PTs. The immunohistochemical assessment of 97 independent cohorts identified that COL4A1/2 and CSRP1 could aid in accurate diagnosis and grading.

CONCLUSIONS

Our study demonstrates that COL4A1/2 shapes the spatial structure of stromal cell differentiation and has important clinical implications for accurate diagnosis of breast PTs.

A Comprehensive Review of Breast Fibroadenoma: Correlating Clinical and Pathological Findings

Breast fibroadenomas, common benign conditions, exhibit distinct clinical and histopathological features. This review highlights clinical presentation and histology correlations, providing insights for healthcare providers. Palpable masses, pain, and changes in breast appearance align with glandular and stromal components, emphasizing accurate diagnosis. Mammography, ultrasound, and MRI guide tailored treatment decisions. Challenges in differentiating atypical fibroadenomas highlight the need for meticulous histopathological evaluation. Clinical implications stress patient-centered care, shared decision-making, and ongoing follow-up. Future research focuses on genetic investigations and long-term studies. A multidisciplinary approach to breast fibroadenomas ensures comprehensive care for improved outcomes in both medical and emotional aspects.

CD146 promotes malignant progression of breast phyllodes tumor through suppressing DCBLD2 degradation and activating the AKT pathway

BACKGROUND

As a rapid-progressing tumor, breast malignant phyllodes tumors (PTs) are challenged by the lack of effective therapeutic strategies and suitable prognostic markers. This study aimed to clarify the role and mechanism of CD146 on promoting PTs malignant progression, and to identify a novel prognosis marker and treatment target of breast malignant PTs.

METHODS

The expression and prognostic significance of CD146 in PTs was detected through single-cell RNA-sequencing (scRNA-seq), immunostaining, real-time PCR and other methodologies. Functional experiments including proliferation assay, colony formation assay, transwell assay, and collagen contraction assay were conducted to validate the role of CD146 in malignant progression of PTs. The efficacy of anti-CD146 monoclonal antibody AA98 against malignant PTs was corroborated by a malignant PT organoid model and a PT patient-derived xenograft (PDX) model. Transcriptome sequencing, proteomic analysis, co-immunoprecipitation, and pull-down assay was employed to identify the modulating pathway and additional molecular mechanism.

RESULTS

In this study, the scRNA-seq analysis of PTs disclosed a CD146-positive characteristic in the α-SMA+ fibroblast subset. Furthermore, a progressive elevation in the level of CD146 was observed with the malignant progression of PTs. More importantly, CD146 was found to serve as an independent predictor for recurrence in PT patients. Furthermore, CD146 was found to augment the viability and invasion of PTs. Mechanistically, CD146 acted as a protective "shield" to prevent the degradation of Discoidin, CUB, and LCCL domain-containing protein 2 (DCBLD2), thereby activating the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway and enhancing malignant behaviors of PT cells. In the malignant PT organoid and PDX model, a significant suppression of malignant PT growth was observed after the application of AA98.

CONCLUSIONS

These findings suggested that CD146 served as an efficacious marker for predicting PT malignant progression and showed promise as a prognosis marker and treatment target of breast malignant PTs. The study further unveiled the essential role of the CD146-DCBLD2/PI3K/AKT axis in the malignant progression of PTs.

Recent Advances in Breast Cancer Research

This Special Issue (SI), titled "Recent Advances in Breast Cancer Research", covers 12 research articles and 1 communication in the field of breast cancer (BC) research [...].