Biological differences between normal and cancer-associated fibroblasts in breast cancer.

Background: Cancer-associated fibroblasts (CAFs) constitute the primary constituents of the tumor microenvironment (TME) and exert significant influences on cancer progression. However, adequate comprehension of CAF profiles in breast cancer, as well as the precise mechanisms underlying their promotion of cancer, remains lacking. Objectives: To discerns the biological differences between normal fibroblasts (NFs) and CAFs in breast cancer and explore the underlying mechanism. Methods: Three pairs of CAFs and NFs were isolated from breast cancer patients of diverse subtypes who had not undergone prior radiotherapy or chemotherapy. Morphological characteristics of CAFs and NFs were assessed through optical and electron microscopy, their biological attributes were examined using cell counting kits and transwell assays, and their impact on breast cancer cells was simulated using a coculture system. Furthermore, the miRNA profiles of CAFs and NFs were sequenced via an Illumina HiSeq 2500 platform. Results: CAFs exhibited higher growth rate and motility than NFs and a stronger potential to promote the malignancy of breast cancer cells. RNA sequencing of both NFs and CAFs revealed differentially expressed miRNAs with notable variability among distinct patients within their NFs and CAFs, while the enrichment of the target genes of differentially expressed miRNAs within both GO terms and KEGG pathways demonstrated significant similarity across patients with different profiles. Conclusion: CAFs have greater malignancy and higher potential to influence the growth, migration, invasion and chemoresistance of cocultured breast cancer cells than NFs. In addition, the miRNAs that are differentially expressed in CAFs when compared to NFs display substantial variability across patients with distinct breast cancer subtypes, while the enrichment of target genes regulated by these miRNAs, within GO terms and KEGG pathways, remains remarkably consistent among patients with varying profiles.

Cancer-associated fibroblasts in breast cancer: Challenges and opportunities.

The tumor microenvironment is proposed to contribute substantially to the progression of cancers, including breast cancer. Cancer-associated fibroblasts (CAFs) are the most abundant components of the tumor microenvironment. Studies have revealed that CAFs in breast cancer originate from several types of cells and promote breast cancer malignancy by secreting factors, generating exosomes, releasing nutrients, reshaping the extracellular matrix, and suppressing the function of immune cells. CAFs are also becoming therapeutic targets for breast cancer due to their specific distribution in tumors and their unique biomarkers. Agents interrupting the effect of CAFs on surrounding cells have been developed and applied in clinical trials. Here, we reviewed studies examining the heterogeneity of CAFs in breast cancer and expression patterns of CAF markers in different subtypes of breast cancer. We hope that summarizing CAF-related studies from a historical perspective will help to accelerate the development of CAF-targeted therapeutic strategies for breast cancer.

Corrigendum: STAT5a Confers Doxorubicin Resistance to Breast Cancer by Regulating ABCB1.

[This corrects the article DOI: 10.3389/fonc.2021.697950.].

Fascin enhances the vulnerability of breast cancer to erastin-induced ferroptosis.

Ferroptosis, which is characterized by intracellular iron accumulation and lipid peroxidation, is a newly described form of regulated cell death that may play a key role in tumour suppression. In the present study, we investigated the expression profiles and biological effects of fascin actin-bundling protein 1 (Fascin, gene name FSCN1) in breast cancer. In addition, bioinformatics analysis of the TCGA cancer database and gain- and loss-of-function studies showed that Fascin enhances sensitivity to erastin-induced ferroptosis. Mechanistically, Fascin directly interacts with cysteine/glutamate transporter (xCT, gene name SLC7A11) and decreases its stability via the ubiquitin-mediated proteasome degradation pathway. Furthermore, we observed that Fascin is substantially upregulated in tamoxifen-resistant breast cancer cell lines, and drug-resistant cells were also more vulnerable to erastin-induced ferroptosis. Taken together, our findings reveal a previously unidentified role of Fascin in ferroptosis by regulating xCT. Thus, ferroptosis activation in breast cancer with high Fascin level may serve as a potential treatment.

STAT5a Confers Doxorubicin Resistance to Breast Cancer by Regulating ABCB1.

Chemoresistance is a daunting challenge to the prognosis of patients with breast cancer. Signal transducer and activator of transcription (STAT) 5a plays vital roles in the development of various cancers, but its function in breast cancer is controversial, and its role in chemoresistance in breast cancer remains unexplored. Here we identified STAT5a as a chemoresistance inducer that regulates the expression of ABCB1 in breast cancer and can be targeted by pimozide, an FDA-approved psychotropic drug. First, we found that STAT5a and ABCB1 were expressed at higher levels in doxorubicin-resistant cell lines and chemoresistant patients, and their expression was positively correlated. Then, we confirmed the essential roles of STAT5a and ABCB1 in doxorubicin resistance in breast cancer cells and the regulation of ABCB1 transcription by STAT5a. Subsequently, the efficacy of pimozide in inhibiting STAT5a and sensitizing doxorubicin-resistant breast cancer cells was tested. Finally, we verified the role of STAT5a in doxorubicin resistance in breast cancer and the efficacy of pimozide in reversing this resistance in vivo. Our study demonstrated the vital role of STAT5a in doxorubicin resistance in breast cancer. Targeting STAT5a might be a promising strategy for treating doxorubicin-resistant breast cancer. Moreover, repurposing pimozide for doxorubicin resensitization is attractive due to the safety profile of pimozide.

Establishment and Characterization of a HER2-Positive Cell Line Derived From the Pleural Effusion of a Drug-Resistant Breast Cancer Patient.

Drug resistance is a daunting challenge in the treatment of breast cancer, making it an urgent problem to solve in studies. Cell lines are important tools in basic and preclinical studies; however, few breast cell lines from drug-resistant patients are available. Herein, we established a novel HER2-positive breast cancer cell line from the pleural effusion of a drug-resistant metastatic breast cancer patient. This cell line has potent proliferative capability and tumorigenicity in nude mice but weak invasive and colony-forming capability. The molecular subtype of the cell line and its sensitivity to chemotherapeutics and HER2-targeting agents are different from those of its origin, suggesting that the phenotype changes between the primary and metastatic forms of breast cancer.

[Retracted] LINC01638 silencing inhibits cancer cell proliferation in colorectal adenocarcinoma through interaction with RUNX2.

Following the publication of the above paper, the authors drew to the Editor's attention that they had identified some errors in Fig. 5A. First, the authors were unable to locate the original images for Fig. 5A; furthermore, repetitions of the same experiments yielded results that were opposite to those that the authors had originally reported. These results were integral to the study, and affected the reported conclusions in the article. Therefore, the authors requested that the paper be withdrawn from the publication. The Editor of Molecular Medicine Reports has considered the authors' request, and agrees that the article should be retracted from the Journal. Note that all that authors agree with the retraction of this paper, and the Editor and the authors apologize to the readership of the Journal for any inconvenience caused. [the original article was published in Molecular Medicine Reports 19: 5275-5280, 2019; DOI: 10.3892/mmr.2019.10191].

Targeting ferroptosis in breast cancer.

Ferroptosis is a recently discovered distinct type of regulated cell death caused by the accumulation of lipid-based ROS. Metabolism and expression of specific genes affect the occurrence of ferroptosis, making it a promising therapeutic target to manage cancer. Here, we describe the current status of ferroptosis studies in breast cancer and trace the key regulators of ferroptosis back to previous studies. We also compare ferroptosis to common regulated cell death patterns and discuss the sensitivity to ferroptosis in different subtypes of breast cancer. We propose that viewing ferroptosis-related studies from a historical angle will accelerate the development of ferroptosis-based biomarkers and therapeutic strategies in breast cancer.

LINC01638 silencing inhibits cancer cell proliferation in colorectal adenocarcinoma through interaction with RUNX2.

lncRNA LINC01638 has been revealed to play an oncogenic role in triple negative breast cancer. The present study was carried out to investigate the involvement of LINC01638 in colorectal adenocarcinoma. In the present study it was observed that LINC01638 in plasma was upregulated in colorectal adenocarcinoma patients compared to healthy controls. Plasma levels of LINC01638 were affected by tumor size but not by distant metastasis. Plasma levels of Runt­related transcription factor 2 (RUNX2) were also higher in colorectal adenocarcinoma patients than in healthy controls, and were positively correlated with plasma levels of LINC01638 in colorectal adenocarcinoma patients but not in healthy controls. ROC curve analysis revealed that upregulation of LINC01638 distinguished colorectal adenocarcinoma at stage I and II from healthy controls. LINC01638 shRNA knockdown led to RUNX2 downregulation, while RUNX2 overexpression exhibited no significant effects on LINC01638. LINC01638 shRNA knockdown inhibited and RUNX2 overexpression promoted the proliferation of colorectal adenocarcinoma cells. RUNX2 overexpression attenuated the effects of LINC01638 shRNA knockdown on cancer cell proliferation. Therefore, lncRNA LINC01638 silencing may inhibit cancer cell proliferation in colorectal adenocarcinoma through its interaction with RUNX2.