Epithelial to mesenchymal transition and microRNA expression are associated with spindle and apocrine cell morphology in triple-negative breast cancer

Abstract

Triple negative breast cancers (TNBC) are a morphologically and genetically heterogeneous group of breast cancers with uncertain prediction of biological behavior and response to therapy. Epithelial to mesenchymal transition (EMT) is a dynamic process characterized by loss of typical epithelial phenotype and acquisition of mesenchymal characteristics. Aberrant activation of EMT can aggravate the prognosis of patients with cancer, however, the mechanisms of EMT and role of microRNAs (miRNAs) in EMT activation is still unclear. The aim of our study was to analyze miRNA expression within areas of TNBCs with cellular morphology that may be related to the EMT process and discuss possible associations. Out of all 3953 re-examined breast cancers, 460 breast cancers were diagnosed as TNBC (11.64%). With regard to complete tumor morphology preservation, the tissue samples obtained from core—cut biopsies and influenced by previous neoadjuvant therapy were excluded. We assembled a set of selected 25 cases to determine miRNA expression levels in relation to present focal spindle cell and apocrine cell morphology within individual TNBCs. We used descriptive (histological typing and morphology), morphometric, molecular (microdissection of tumor and non-tumor morphologies, RNA isolation and purification, microchip analysis) and bioinformatic analysis (including pathway analysis). The results were verified by quantitative real-time PCR (RT-qPCR) on an extended set of 70 TNBCs. The majority of TNBCs were represented by high—grade invasive carcinomas of no special type (NST) with medullary features characterized by well-circumscribed tumors with central necrosis or fibrosis and frequent tendency to spindle-cell and/or apocrine cell transformation. Apocrine and spindle cell transformation showed a specific miRNA expression profile in comparison to other tumor parts, in situ carcinoma or non-tumor structures, particularly down-regulated expression of hsa-miRNA-143-3p and hsa-miRNA-205-5p and up-regulated expression of hsa-miR-22-3p, hsa-miRNA-185-5p, and hsa-miR-4443. Apocrine cell tumor morphology further revealed decreased expression of hsa-miR-145-5p and increased expression of additional 14 miRNAs (e.g. hsa-miR-182-5p, hsa-miR-3135b and hsa-miR-4417). Pathway analysis for target genes of these miRNAs revealed several shared biological processes (i.e. Wnt signaling, ErbB signaling, MAPK signaling, endocytosis and axon guidance), which may in part contribute to the EMT and tumor progression. We provide the first miRNA expression profiling of specific tissue morphologies in TNBC. Our results demonstrate a specific miRNA expression profile of apocrine and spindle cell morphology which can exhibit a certain similarity with the EMT process and may also be relevant for prognosis and therapy resistance of TNBC.

An Update on the Molecular and Clinical Characteristics of Apocrine Carcinoma of the Breast

“…The pathway analysis revealed that these miRNAs closely interfere with several important signaling pathways, such as Wnt, ErbB/HER2, and MAPK pathways; the authors also speculated that these miRNAs might contribute to EMT in special types of TNBC -apocrine and spindle cell (metaplastic) carcinomas, concluding that further mechanistic studies are essential to confirm their observations. 42 Notably, we also demonstrated the EMT in a case of morphologically apocrine DCIS (AR + ) harboring PTEN and HRAS mutations with progression to spindle cell metaplastic carcinoma that had the same mutational profile and a loss of AR expression. 43 EMT was supported by the loss of E-cadherin protein (without CDH1 gene mutations or loss) and nuclear ß-catenin expression in invasive spindle cell component.…”

“…41 miRNAs have been extensively characterized in various cancers, including breast cancer. Recently, Koleckova et al 42 demonstrated that triple-negative breast carcinomas with apocrine and spindle cell (metaplastic) morphology exhibited a distinct miRNA profile compared with other breast cancers. In particular, they showed the downregulation of hsa-miRNA-143-3p and hsa-miRNA-205-5p and upregulation of the hsa-miR-22-3p, hsa-miRNA-185-5p, and hsa-miR-4443 ( Table 2 ).…”

miR-145-5p Mimic Inhibits Bone Metastasis of Prostate Cancer Via the Regulation of Epithelial Mesenchymal Transition

“…This suggests that miR-145-5p inhibits PC-3 cell metastasis and promotes PC-3 cell apoptosis. Moreover, the expression of hsa-miR-145-5p is also decreased in tumor transformational apocrine and spindle cells compared to in situ carcinoma or nonttumor structures [37]. This indicates that miR-145-5p has a potential regulatory effect on cancer metastasis.…”

Potential Anti-Metastatic Role of the Novel miR-CT3 in Tumor Angiogenesis and Osteosarcoma Invasion

“…During several steps of metastasis, the cancer cells disseminate into other organs via EMT. Furthermore, it is well known that miRNAs play a pivotal role in the regulation of EMT phenotype, also in OS cells [ 43 , 49 , 50 , 51 ]. Hence, we investigated the potential role of miR-CT3 in regulating expression of EMT-factors.…”