Molecular therapy of breast cancer: progress and future directions

Advanced machine learning framework for enhancing breast cancer diagnostics through transcriptomic profiling

PURPOSE

This study proposes an advanced machine learning (ML) framework for breast cancer diagnostics by integrating transcriptomic profiling with optimized feature selection and classification techniques.

MATERIALS AND METHODS

A dataset of 1759 samples (987 breast cancer patients, 772 healthy controls) was analyzed using Recursive Feature Elimination, Boruta, and ElasticNet for feature selection. Dimensionality reduction techniques, including Non-Negative Matrix Factorization (NMF), Autoencoders, and transformer-based embeddings (BioBERT, DNABERT), were applied to enhance model interpretability. Classifiers such as XGBoost, LightGBM, ensemble voting, Multi-Layer Perceptron, and Stacking were trained using grid search and cross-validation. Model evaluation was conducted using accuracy, AUC, MCC, Kappa Score, ROC, and PR curves, with external validation performed on an independent dataset of 175 samples.

RESULTS

XGBoost and LightGBM achieved the highest test accuracies (0.91 and 0.90) and AUC values (up to 0.92), particularly with NMF and BioBERT. The ensemble Voting method exhibited the best external accuracy (0.92), confirming its robustness. Transformer-based embeddings and advanced feature selection techniques significantly improved model performance compared to conventional approaches like PCA and Decision Trees.

CONCLUSION

The proposed ML framework enhances diagnostic accuracy and interpretability, demonstrating strong generalizability on an external dataset. These findings highlight its potential for precision oncology and personalized breast cancer diagnostics.

Autophagy Deficiency Induced by SAT1 Potentiates Tumor Progression in Triple-Negative Breast Cancer

Aggressive triple-negative breast cancer (TNBC) still lacks approved targeted therapies, requiring more exploration of its underlying mechanisms. Previous studies have suggested a potential role of SAT1 (Spermidine/Spermine N1-acetyltransferase 1) in cancer, which needs to be further elucidated in breast cancer. In this study, highly expressed SAT1 in TNBC signified worse patient prognoses. And SAT1 knockdown effectively inhibited the proliferation and migration abilities of TNBC cells in vitro and in vivo. In terms of mechanism, the transcription factor JUN enhanced SAT1 transcriptional activity by binding to its promoter region. Then, SAT1 protein in the cytoplasm engaged in directly binding with YBX1 for sustaining YBX1 protein stability via deubiquitylation mediated by the E3 ligase HERC5. Further, SAT1 was found to suppress autophagy remarkably via stabilization of mTOR mRNA with the accumulation of YBX1-mediated methyl-5-cytosine (m5C) modification. These findings proved that SAT1 drives TNBC progression through the SAT1/YBX1/mTOR axis, which may provide a potential candidate for targeted therapy in advanced TNBC.

Genetically evaluating the causal role of peripheral immune cells in colorectal cancer: a two-sample Mendelian randomization study

BACKGROUND

Investigating novel therapeutic strategies for colorectal cancer (CRC) is imperative. However, there is limited research on the use of drugs to target peripheral blood immune cells in this context. To address this gap, we performed a two-sample Mendelian randomization (MR) analysis to identify potential therapeutic targets for CRC.

METHODS

We applied two-sample MR to identify the causal relationship between peripheral blood immune cells and CRC. GWAS data were obtained from the IEU OPEN GWAS project. Based on the implications from the MR results, we conducted a comprehensive database search and genetic analysis to explore potential underlying mechanisms. We predicted miRNAs for each gene and employed extensive research for potential therapeutic applications.

RESULTS

We have identified causal associations between two peripheral immune cells and colorectal cancer. Activated & resting Treg %CD4 + cell was positively associated with the risks of CRC, while DN (CD4-CD8-) %leukocyte cell exhibited a protective role in tumor progression. NEK7 (NIMA related kinase 7) and LHX9 (LIM homeobox 9) expressed in Treg cells were positively associated with CRC risks and may play a vital role in carcinogenesis.

CONCLUSIONS

This study identified causal relationship between peripheral immune cell and CRC. Treg and DN T cells were implicated to own promoting and inhibiting effects on CRC progression respectively. NEK7 and LHX9 in Treg cells were identified as potential biotarget for antitumor therapies.

Inhibitors Targeting the F-BOX Proteins

F-box proteins are involved in multiple cellular processes through ubiquitylation and consequent degradation of targeted substrates. Any significant mutation in F-box protein-mediated proteolysis can cause human malformations. The various cellular processes F-box proteins involved include cell proliferation, apoptosis, invasion, angiogenesis, and metastasis. To target F-box proteins and their associated signaling pathways for cancer treatment, researchers have developed thousands of F-box inhibitors. The most advanced inhibitor of FBW7, NVD-BK M120, is a powerful P13 kinase inhibitor that has been proven to bring about apoptosis in cancerous human lung cells by disrupting levels of the protein known as MCL1. Moreover, F-box Inhibitors have demonstrated their efficacy for treating certain cancers through targeting particular mutated proteins. This paper explores the key studies on how F-box proteins act and their contribution to malignancy development, which fabricates an in-depth perception of inhibitors targeting the F-box proteins and their signaling pathways that eventually isolate the most promising approach to anti-cancer treatments.

The tumor-nerve circuit in breast cancer

It is well established that innervation is one of the updated hallmarks of cancer and that psychological stress promotes the initiation and progression of cancer. The breast tumor environment includes not only fibroblasts, adipocytes, endothelial cells, and lymphocytes but also neurons, which is increasingly discovered important in breast cancer progression. Peripheral nerves, especially sympathetic, parasympathetic, and sensory nerves, have been reported to play important but different roles in breast cancer. However, their roles in the breast cancer progression and treatment are still controversial. In addition, the brain is one of the favorite sites of breast cancer metastasis. In this review, we first summarize the innervation of breast cancer and its mechanism in regulating cancer growth and metastasis. Next, we summarize the neural-related molecular markers in breast cancer diagnosis and treatment. In addition, we review drugs and emerging technologies used to block the interactions between nerves and breast cancer. Finally, we discuss future research directions in this field. In conclusion, the further research in breast cancer and its interactions with innervated neurons or neurotransmitters is promising in the clinical management of breast cancer.

New insights into the substrate inhibition of human 17β-hydroxysteroid dehydrogenase type 1

Human type 1 17β-hydroxysteroid dehydrogenase (17β-HSD1),a member of the short-chain dehydrogenase/reductase family, catalyzes the last step in the bioactivation of the most potent estrogen estradiol with high specificity and is thus involved in estrogen-dependent diseases. As an oxidoreductase, 17β-HSD1 can utilize both triphosphate and diphosphate cofactors in reaction at the molecular level, but more specific with triphosphate cofactor. The NADPH is much higher than NADP+ in living cells leading to preliminary reduction action. The enzyme also showed substrate-induced inhibition unprecedented in other members of 17β-HSDs. Our previous study elucidated the structural mechanism of substrate inhibition is due to the reversely bound estrone (E1) in the substrate-binding pocket of the enzyme resulting in a dead-end complex. However, the effect of the cofactor preference on the substrate inhibition of the enzyme is not yet clear. In the present study, we solved the ternary crystal structures of 17β-HSD1 in complex with E1 and cofactor analog NAD+ . Combined with molecular dynamics simulation using the enzyme with NADH/NADPH and different oriented E1 (normally oriented, E1N; reversely oriented, E1R), such ternary structure provides a complete picture of enzyme-substrate-cofactor interactions. The results reveal that different cofactors and substrate binding mode affect the allosteric effect between the two subunits of the enzyme. And the results from MD simulations confirmed that His²²¹ plays a key role in the formation of dead-end complex in NADPH complex, and the absence of stable interaction between His²²¹ and E1R in the NADH complex should be the main reason for its lack of substrate inhibition.

NCAPD2 promotes breast cancer progression through E2F1 transcriptional regulation of CDK1

Breast cancer (BC) is a serious threat to women's health worldwide. Non-SMC condensin I complex subunit D2 (NCAPD2) is a regulatory subunit of the coagulin I complex, which is mainly involved in chromosome coagulation and separation. The clinical significance, biological behavior, and potential molecular mechanism of NCAPD2 in BC were investigated in this study. We found that NCAPD2 was frequently overexpressed in BC, and it had clinical significance in predicting the prognosis of BC patients. Moreover, loss-of-function assays demonstrated that NCAPD2 knockdown restrained the progression of BC by inhibiting proliferation and migration and enhancing apoptosis in vitro. It was further confirmed that the downregulation of NCAPD2 inhibited tumor growth in vivo. NCAPD2 promoted the progression of BC through the extracellular signal-regulated kinase 5 (ERK5) signaling pathway. Additionally, NCAPD2 could transcriptionally activate CDK1 by interacting with E2F transcription factor 1 (E2F1) in MDA-MB-231 cells. Overexpression of CDK1 alleviated the inhibitory effects of NCAPD2 knockdown in BC cells. In summary, the NCAPD2/E2F1/CDK1 axis may play a role in promoting the progression of BC, which may provide a blueprint for molecular therapy.

Dual Targeting of Steroid Sulfatase and 17β-Hydroxysteroid Dehydrogenase Type 1 by a Novel Drug-Prodrug Approach: A Potential Therapeutic Option for the Treatment of Endometriosis

A novel approach for the dual inhibition of steroid sulfatase (STS) and 17β-hydroxysteroid dehydrogenase type 1(17β HSD1) by a single drug was explored, starting from in-house 17β HSD1 inhibitors via masking their phenolic OH group with a sulfamate ester. The sulfamates were intentionally designed as drugs for the inhibition of STS and, at the same time, prodrugs for 17β-HSD1 inhibition ("drug-prodrug approach"). The most promising sulfamates 13, 16, 18-20, 22-24, 36, and 37 showed nanomolar IC₅₀ values for STS inhibition in a cellular assay and their corresponding phenols displayed potent 17β-HSD1 inhibition in cell-free and cellular assays, high selectivity over 17β-HSD2, reasonable metabolic stability, and low estrogen receptor α affinity. A close relationship was found between the liberation of the phenolic compound by sulfamate hydrolysis and 17β-HSD1 inactivation. These results showed that the envisaged drug-prodrug concept was successfully implemented. The novel compounds constitute a promising class of therapeutics for the treatment of endometriosis and other estrogen-dependent diseases.

MiR-4458-loaded gelatin nanospheres target COL11A1 for DDR2/SRC signaling pathway inactivation to suppress the progression of estrogen receptor-positive breast cancer

RNA interference is a promising way to treat cancer and the construction of a stable drug delivery system is critically important for its application. Gelatin nanospheres (GNs) comprise a biodegradable drug vehicle with excellent biocompatibility, but there are limited studies on its delivery and role in the stabilization of miRNA and siRNA. Breast cancer is the most diagnosed type of female cancer worldwide. Abnormal miRNA expression is closely related to the occurrence and progression of estrogen receptor-positive (ER+) breast cancer. In this study, miR-4458 was upregulated in ER+ breast cancer and could inhibit MCF-7 cell viability, colony formation, migration, and invasion. Collagen type XI alpha 1 (COL11A1) was identified as a directly interacting protein of miR-4458 and an important component of the extracellular matrix. High COL11A1 expression was positively correlated with poor prognosis, lower overall survival, disease-free survival, and a late tumor-node-metastasis stage. COL11A1 knockdown could inhibit MCF-7 cell migration and invasion. GNs were used to load a miR-4458 mimic or COL11A1 siRNA (si-COL11A1) to achieve sustained and controlled release in xenograft nude mice. Their tumor volume was decreased, tumor cell apoptosis was promoted, and hepatic metastasis was significantly inhibited. Moreover, the DDR2/SRC signaling pathway was inactivated after transfection with the miR-4458 mimic and si-COL11A1. In conclusion, GNs can be potentially used to deliver siRNA or miRNA, and miR-4458 and COL11A1 can be possible targets for ER+ breast cancer treatment.

Tumour-suppressing functions of the lncRNA MBNL1-AS1/miR-889-3p/KLF9 axis in human breast cancer cells

This study aimed to explore the role and potential mechanism of the long non-coding (lncRNA) MBNL1-AS1 in human breast cancer. We included 80 patients with breast cancer in this study. Breast cancer cell lines, including MCF7, SKBR3, MDA-MB-231 and MDA-MB-415, and the normal human breast cell line MCF10A were used in this study. MBNL1-AS1, miR-889-3p mimics, si-Krüppel-like factor 9 (KLF9) or their controls were transfected in the cells. Quantitative reverse transcription polymerase chain reaction (qRT-PCR), Western blotting and immunohistochemistry assay were performed to detect the expression of MBNL1-AS1, miR-889-3p and KLF9. Cell proliferation, invasion and migration were detected. Luciferase reporter gene and pull-down assay were performed to verify the target relationship among MBNL1-AS1, miR-889-3p and KLF9. Glycolysis was also detected after transfection. The expression of the lncRNA MBNL1-AS1 was low in the breast cancer tissues and cells. Lower expression levels of the lncRNA MBNL1-AS1 were associated with poor prognosis of breast cancer. Overexpression of the lncRNA MBNL1-AS1 decreased proliferation, invasion, migration and glycolysis of breast cancer cells. The lncRNA MBNL1-AS1 could interact with miR-889-3p, and KLF9 was the downstream target of miR-889-3p. Moreover, miR-889-3p was negatively correlated with KLF9 and lncRNA MBNL1-AS1. Both miR-889-3p and si-KLF9 could reverse the overexpression of lncRNA MBNL1-AS1 in breast cancer development. The lncRNA MBNL1-AS1 decreased proliferation, invasion, migration and glycolysis of breast cancer via the miR-889-3p/KLF9 axis, which might be a potential biomarker for the diagnosis of breast cancer.

Development of a Model System to Study Expression Profile of RAC2 Gene in Breast Cancer MDA-MB-231 Cell Line

The RAC2 gene encoding GTPases involve cellular signaling of actin polymerization, cell migration, and formation of the phagocytic NADPH oxidase complex. Oncogenic mutations in the RAC2 gene have been identified in various cancers, and extensive research is in progress to delineate its signaling pathways and identify potential therapeutic targets in breast cancers. This paper explored developing a bioinformatics model system to understand the RAC2 gene expression pattern concerning estrogenic receptor status in breast cancers. We have used the MDA-MB-231 breast cancer cell line to identify RAC2 gene expression. To simplify the development of model system with one dataset, we retrieved the microarray dataset GSE27515 from the Gene Expression Omnibus (GEO) for the differential gene expression analysis. Then, network analysis, pathway enrichment analysis, volcano plot, ORA, and the up/downregulated genes were used to highlight genes involved in signaling network pathways. We observed that the RAC2 gene is upregulated in the GSM679722, GSM676923, and GSM679724 downregulated in the samples GSM676925, GSM676926, and GSM676927 from the GEO dataset. Our observation found that the RAC2 gene is upregulated in the estrogen receptor (ER) negative breast cancers and downregulated in ER-positive breast cancer, involving pathways such as focal adhesion, MAPK signaling, axon guidance, and VEGF signaling pathway.

Identification of a DNA Methylation-Driven Genes-Based Prognostic Model and Drug Targets in Breast Cancer: In silico Screening of Therapeutic Compounds and in vitro Characterization

DNA methylation is a vital epigenetic change that regulates gene transcription and helps to keep the genome stable. The deregulation hallmark of human cancer is often defined by aberrant DNA methylation which is critical for tumor formation and controls the expression of several tumor-associated genes. In various cancers, methylation changes such as tumor suppressor gene hypermethylation and oncogene hypomethylation are critical in tumor occurrences, especially in breast cancer. Detecting DNA methylation-driven genes and understanding the molecular features of such genes could thus help to enhance our understanding of pathogenesis and molecular mechanisms of breast cancer, facilitating the development of precision medicine and drug discovery. In the present study, we retrospectively analyzed over one thousand breast cancer patients and established a robust prognostic signature based on DNA methylation-driven genes. Then, we calculated immune cells abundance in each patient and lower immune activity existed in high-risk patients. The expression of leukocyte antigen (HLA) family genes and immune checkpoints genes were consistent with the above results. In addition, more mutated genes were observed in the high-risk group. Furthermore, a in silico screening of druggable targets and compounds from CTRP and PRISM databases was performed, resulting in the identification of five target genes (HMMR, CCNB1, CDC25C, AURKA, and CENPE) and five agents (oligomycin A, panobinostat, (+)-JQ1, voxtalisib, and arcyriaflavin A), which might have therapeutic potential in treating high-risk breast cancer patients. Further in vitro evaluation confirmed that (+)-JQ1 had the best cancer cell selectivity and exerted its anti-breast cancer activity through CENPE. In conclusion, our study provided new insights into personalized prognostication and may inspire the integration of risk stratification and precision therapy.

miR-506-loaded gelatin nanospheres target PENK and inactivate the ERK/Fos signaling pathway to suppress triple-negative breast cancer aggressiveness

Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer. Some microRNAs (miRNAs) were abnormally expressed in TNBC, and they are closely related to the occurrence and progression of TNBC. Here, we found that miR-506 was significantly downregulated in TNBC and relatively lower miR-506 expression predicted a poorer prognosis. Moreover, we found that miR-506 could inhibit MDA-MB-231 cell viability, colony formation, migration, and invasion, and suppress the ERK/Fos oncogenic signaling pathway through upregulating its direct target protein proenkephalin (PENK). Therefore, miR-506 was proposed as a nucleic acid drug for TNBC therapy. However, miRNA is unstable in vivo, which limiting its application as a therapeutic drug via conventional oral or injected therapies. Here, a gelatin nanosphere (GN) delivery system was applied for the first time to load exogenous miRNA. Exogenous miR-506 mimic was loaded on GNs and injected into the in situ TNBC animal model, and the miR-506 could achieve sustained and controlled release. The results confirmed that overexpression of miR-506 and PENK in vivo through loading on GNs inhibited in situ triple-negative breast tumor growth and metastasis significantly in the xenograft model. Moreover, we indicated that the ERK/Fos signaling pathway was intensively inactivated after overexpression of miR-506 and PENK both in vitro and in vivo, which was further validated by the ERK1/2-specific inhibitor SCH772984. In conclusion, this study demonstrates that miR-506-loaded GNs have great potential in anti-TNBC aggressiveness therapy.

Progress of non-coding RNAs in triple-negative breast cancer

Non-coding RNAs (ncRNAs) include miRNA, lncRNA, and circRNA. NcRNAs are involved in multiple biological processes, including chromatin remodeling, signal transduction, post-transcriptional modification, cell autophagy, carbohydrate metabolism, and cell cycle regulation. Triple negative breast cancer (TNBC) is notorious for high invasiveness and metastasis, poor prognosis, and high mortality, and it is the most malignant breast cancer, while the effective targets for TNBC treatment are still lacking. NcRNAs act as oncogenes or suppressor genes, as well as promote or inhibit the occurrence and development of TNBC. Here, we reviewed some important miRNAs, lncRNAs, circRNAs, their target(s) and molecular mechanisms in TNBC. It is benefited to understand the occurrence and development of TNBC, further some ncRNAs might be potential targets for TNBC treatment.

Novel alkylaminoethyl derivatives of androstane 3-oximes as anticancer candidates: synthesis and evaluation of cytotoxic effects

Steroid anticancer drugs are the focus of numerous scientific research efforts. Due to their high cytotoxic effects against tumor cells, some natural or synthetic steroid compounds seem to be promising for the treatment of different classes of cancer. In the present study, fourteen novel O-alkylated oxyimino androst-4-ene derivatives were synthesized from isomerically pure 3E-oximes, using different alkylaminoethyl chlorides. Their in vitro cytotoxic activity was evaluated against eight human cancer cell lines, as well as against normal fetal lung (MRC-5) and human foreskin (BJ) fibroblasts, to test the efficiency and selectivity of the compounds. Most derivatives displayed strong activity against malignant melanoma (G-361), lung adenocarcinoma (A549) and colon adenocarcinoma (HT-29) cell lines. Angiogenesis was assessed in vitro using migration scratch and tube formation assays on HUVEC cells, where partial inhibition of endothelial cell migration was observed for the 17α-(pyridin-2-yl)methyl 2-(morpholin-4-yl)ethyl derivative. Among the compounds that most impaired the growth of lung cancer A549 cells, the (17E)-(pyridin-2-yl)methylidene derivative bearing a 2-(pyrrolidin-1-yl)ethyl substituent induced significant apoptosis in these cells. In combination with low cytotoxicity toward normal MRC-5 cells, this molecule stands out as a good candidate for further anticancer studies. In addition, in vitro investigations against cytochrome P450 enzymes revealed that certain compounds can bind selectively in the active sites of human steroid hydroxylases CYP7, CYP17A1, CYP19A1 or CYP21A2, which could be important for the development of novel activity modulators of these enzymes and identification of possible side effects.

Novel steroid O-alkylated 3-oxyimino derivatives were synthesized and evaluated in vitro for their antitumor properties. The obtained data indicate the potential of these functionalities for the development of new candidates for tumor treatment.

PTPRA facilitates cancer growth and migration via the TNF-α-mediated PTPRA-NF-κB pathway in MCF-7 breast cancer cells

Protein tyrosine phosphatase receptor type A (PTPRA), one of the classic protein tyrosine phosphatases, is crucial for modulating tumorigenesis and metastasis in breast cancer; however, its functional mechanism has not fully elucidated. The present study assessed PTPRA expression and estimated its clinical impact on survival using the Gene Expression Profiling Interactive Analysis database (GEPIA). Growth curves, colony formations and Transwell assays were utilized to examine cell proliferation and migration. Additionally, luciferase reporter assays were used to examine the potential tumor signaling pathways targeted by PTPRA in HEK293T cells. Furthermore, quantitative PCR (qPCR) was utilized to confirm the transcriptional regulation of PTPRA expression. Bioinformatic analyses of data from GEPIA identified PTPRA overexpression in patients with breast cancer. The growth curve, colony formation and transwell experiments demonstrated that PTPRA upregulation significantly promoted the cell proliferation and migration of MCF-7 breast cancer cells. In contrast, PTPRA knockdown significantly attenuated cell proliferation and migration. Mechanistic experiments revealed that the transcriptional activity of NF-κB was higher compared with other classic tumor pathways when they were activated by PTPRA in HEK293T cells. Furthermore, the transcriptional activity of NF-κB was altered in a PTPRA-dose-dependent manner. Additionally, following exposure to TNF-α, PTPRA-deficient MCF-7 cells exhibited lower NF-κB transcriptional activity compared with normal control cells. The results of the present study demonstrate that PTPRA overexpression accelerates inflammatory tumor phenotypes in breast cancer and that the TNF-α-mediated PTPRA-NF-κB pathway may offer novel insight into early diagnosis and optimum treatment for breast cancer.

Long-term survival among 5-year survivors of adolescent and young adult cancer

BACKGROUND

Although there are a growing number of survivors of adolescent and young adult (AYA) cancer, to the authors' knowledge the long-term overall survival (OS) patterns for AYA cancer survivors are underreported. The objective of the current study was to assess the long-term survival of AYA cancer survivors and identify factors associated with diminished long-term survival.

METHODS

The authors used The University of Texas MD Anderson Cancer Center's tumor registry to identify 5-year survivors of cancer diagnosed as AYAs (ages 15-39 years) between the years 1970 and 2005, and who were alive 5 years after diagnosis. Kaplan-Meier curves were used to estimate OS rates over time, and Cox proportional hazards models were fitted to evaluate the association of covariates with OS.

RESULTS

The authors identified 16,728 individuals who were 5-year survivors of cancer and were diagnosed as AYAs with a median follow-up of 20.0 years. The 10-year, 20-year, and 25-year OS rates were 86% (95% confidence interval [95% CI], 85%-86%), 74% (95% CI, 73%-75%), and 68% (95% CI, 67%-68%), respectively, all of which were lower than the age-adjusted estimated survival rates of the general population. Long-term OS improved for AYAs diagnosed between 2000 and 2005 compared with those diagnosed in the prior decades (P < .001). Older age at the time of diagnosis, receipt of radiation, and diagnoses including central nervous system tumors and breast cancer each were associated with diminished long-term survival.

CONCLUSIONS

AYA cancer survivors have inferior long-term survival compared with the general population. Studies investigating the prevalence and types of late treatment effects and causes of death among AYA survivors are needed to more accurately identify AYAs who are at highest risk of early or late mortality.

Estradiol-Induced MMP-9 Expression via PELP1-Mediated Membrane-Initiated Signaling in ERα-Positive Breast Cancer Cells

Proline-, glutamic acid-, leucine-rich protein 1 (PELP1) is a novel estrogen receptor (ER) coregulator, demonstrated distinctive characters from other ERα coregulators, and has been suggested to be involved in metastasis of several cancers. In ERα-positive breast cancer, PELP1 overexpression enhanced ruffles and filopodium-like structure stimulated by estradiol (E₂) through extranuclear cell signaling transduction hereby increased cell motility. However, whether PELP1 is also involved in extracellular matrix remodeling of ERα-positive breast cancer cells is still unknown. In this study, we investigated the role of PELP1 in E₂-induced MMP-9 expression and the underlined mechanism. The results demonstrated the following: E₂-induced ERα-positive MCF-7 breast cancer cell MMP-9 mRNA and protein expression in a rapid response and concentration-dependent manner. Knocked down PELP1 significantly suppressed E₂-induced MMP-9 expression. E₂-bovine serum albumin (BSA), a large molecular membrane-impenetrable conjugate of E₂, can also upregulate MMP-9 protein expression in MCF-7, and the action of E₂-BSA can be abolished by PI3K inhibitor LY294002; treating MCF-7 simultaneously with PELP1-shRNA and LY294002 did not show synergetic inhibitory effect on E₂-BSA-induced MMP-9 expression. Our results indicated that estrogen-induced MMP-9 expression in ER-positive breast cancer cells may be through PELP1-mediated PI3K/Akt signaling pathway.

Steroid enzyme and receptor expression and regulations in breast tumor samples - A statistical evaluation of public data

In spite of the significant progress of estrogen-dependent breast cancer (BC) treatment, aromatase inhibitor resistance is a major problem limiting the clinical benefit of this frontier endocrine-therapy. The aim of this study was to determine the differential expression of steroid-converting enzymes between tumor and adjacent normal tissues, as well as their correlation in modulating intratumoral steroid-hormone levels in post-menopausal estrogen-dependent BC. RNA sequencing dataset (n = 1097) of The-Cancer-Genome-Atlas (Breast Invasive Carcinoma) retrieved through the data portal of Genomic Data Commons was used for differential expressions and expression correlation analyses by Mann-Whitney U and Spearman's rank test, respectively. The results showed significant up-regulation of 17β-HSD7 (2.50-fold, p < 0.0001) in BC, supporting its effect in sex-hormone control. Besides, suppression of 11β-HSD1 expression (-8.29-fold, p < 0.0001) and elevation of 11β-HSD2 expression (2.04-fold, p < 0.0001) provide a low glucocorticoid environment diminishing BC anti-proliferation. Furthermore, 3α-HSDs were down-regulated (-1.59-fold, p < 0.01; -8.18-fold, p < 0.0001; -33.96-fold, p < 0.0001; -31.85-fold, p < 0.0001 for type 1-4, respectively), while 5α-reductases were up-regulated (1.41-fold, p < 0.0001; 2.85-fold, p < 0.0001; 1.70-fold, p < 0.0001 for type 1-3, respectively) in BC, reducing cell proliferation suppressers 4-pregnenes, increasing cell proliferation stimulators 5α-pregnanes. Expression analysis indicates significant correlations between 11β-HSD1 with 3α-HSD4 (r = 0.605, p < 0.0001) and 3α-HSD3 (r = 0.537, p < 0.0001). Significant expression correlations between 3α-HSDs were also observed. Our results systematically present the regulation of steroid-converting enzymes and their roles in modulating the intratumoral steroid-hormone levels in BC with a vivid 3D-schema, supporting novel therapy targeting the reductive 17β-HSD7 and proposing a new combined therapy targeting 11β-HSD2 and 17β-HSD7.

Genetic Profiling of Breast Cancer with and Without Preexisting Metabolic Disease

Breast cancer is the most commonly diagnosed cancer and the leading cause of cancer death among women. Various mechanisms are involved in the initiation and progression of breast cancer. Metabolic dysregulation has been associated with increasing breast cancer incidence and mortality. However, little is known about how metabolic disease regulates the development and progression of breast cancer at the molecular level. Here, using a hybridization capture-based panel including 124 cancer-associated genes, we performed targeted next-generation sequencing of tumor tissues and matched blood samples from 20 postmenopausal patients with primary breast cancer, in which 6 cases suffered from preexisting metabolic disorders including hypertension, type 2 diabetes, and coronary heart disease. We took only the protein-altering variants and identified 170 somatic mutations of 59 genes. Among these, 40 mutated genes were found in the metabolic disease group, and 33 mutated genes were found in the non-metabolic disease group. Importantly, nonsynonymous mutations of 26 genes (MSH3, BRAF, MLH3, MTOR, DDR2, ALK, etc.) were uniquely present in the metabolic disease group. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes enrichment analysis were performed to investigate biological functions and key pathways of somatic mutations. TP53, PIK3CA, and PTEN were the top three commonly mutated genes at a higher frequency compared with the Cancer Genome Atlas (TCGA) data, and several novel but infrequent mutations in other genes were also found. Although further studies are required to validate these variants, our results are the first to suggest a specific molecular profile of breast cancer with preexisting metabolic disease.

Transcriptome of 17β-hydroxysteroid dehydrogenase type 2 plays both hormone-dependent and hormone-independent roles in MCF-7 breast cancer cells

Breast cancer is a major cause of cancer-related death for women in western countries. 17β-Hydroxysteroid dehydrogenases (17β-HSDs) play important roles in the last step of sex-hormone activation and the first step of sex-hormone inactivation. 17β-HSD2 is responsible for oxidizing the sex hormones. We used microarray technology to analyze the effect of 17β-HSD2 on the MCF-7 cell transcript profile after knocking down 17β-HSD2. Five hundred forty-two genes were regulated 1.5-fold or higher after treatment with 17β-HSD2 siRNA. Knocking down 17β-HSD2 interrupted nucleosome assembly. Pathway-Act-Network analysis showed that the MAPK and apoptosis signaling pathways were most regulated. In the gene-gene interaction network analysis, UGT2B15, which is involved in hormone metabolism, was the most regulated core gene. FOS, GREB1, and CXCL12 were the most regulated genes, and CXCL12 was related to tumor migration. Following 17β-HSD2 knock-down, the cell viability decreased to 75.9%. The S-phase percentage decreased by 19.4%, the Q2-phase percentage in cell apoptosis testing increased by 1.5 times, and cell migration decreased to 66.0%. These results were consistent with our gene chip analysis and indicated that 17β-HSD2 plays both hormone-dependent and hormone-independent enzymatic roles. In-depth investigations of this enzyme on the genomic level will help clarify its related molecular mechanisms.

Recent treatment progress of triple negative breast cancer

Breast cancer (BC) is a serious worldwide disease that threatens women's health. Particularly, the morbidity of triple-negative breast cancer (TNBC) is higher than that of other BC types due to its high molecular heterogeneity, metastatic potential and poor prognosis. TNBC lacks of estrogen receptor (ER), progesterone receptor (PR) and human epidermal growth factor receptor 2 (HER2), so there are still no effective treatment methods for TNBC. Here, we reviewed the classification of TNBC, its molecular mechanisms of pathogenesis, treatment methods and prognosis. Finding effective targets is critical for the treatment of TNBC. Also, refining the classification of TNBC is benefited to choose the treatment of TNBC, because the sensitivity of chemotherapy is different in different TNBC. Some new treatment methods have been proposed in recent years, such as nutritional therapy and noncoding RNA treatment methods. There are some disadvantages, such as the side effect on normal cells after nutrient deprivation, low specificity and instability of noncoding RNA. More studies are necessary to improve the treatment of TNBC.

Comparison of the roles of estrogens and androgens in breast cancer and prostate cancer

Breast cancer (BC) and prostate cancer (PC) are the second most common malignant tumors in women and men in western countries, respectively. The risks of death are 14% for BC and 9% for PC. Abnormal estrogen and androgen levels are related to carcinogenesis of the breast and prostate. Estradiol stimulates cancer development in BC. The effect of estrogen on PC is concentration-dependent, and estrogen can regulate androgen production, further affecting PC. Estrogen can also increase the risk of androgen-induced PC. Androgen has dual effects on BC via different metabolic pathways, and the role of the androgen receptor (AR) in BC also depends on cell subtype and downstream target genes. Androgen and AR can stimulate both primary PC and castration-resistant PC. Understanding the mechanisms of the effects of estrogen and androgen on BC and PC may help us to improve curative BC and PC treatment strategies.

TRAIL Mediated Signaling in Breast Cancer: Awakening Guardian Angel to Induce Apoptosis and Overcome Drug Resistance

Sequencing technologies have allowed us to characterize highly heterogeneous molecular landscape of breast cancer with unprecedented details. Tremendous breakthroughs have been made in unraveling contributory role of signaling pathways in breast cancer development and progression. It is becoming progressively more understandable that deregulation of spatio-temporally controlled pathways underlie development of resistance against different drugs. TRAIL mediated signaling has attracted considerable appreciation because of its characteristically unique ability to target cancer cells while leaving normal cells intact. Discovery of TRAIL was considered as a paradigm shift in molecular oncology because of its conspicuous ability to selectively target cancer cells. There was an exponential growth in the number of high-quality reports which highlighted cancer targeting ability of TRAIL and scientists worked on the development of TRAIL-based therapeutics and death receptor targeting agonistic antibodies to treat cancer. However, later studies challenged simplistic view related to tumor targeting ability of TRAIL. Detailed mechanistic insights revealed that overexpression of anti-apoptotic proteins, inactivation of pro-apoptotic proteins and downregulation of death receptors were instrumental in impairing apoptosis in cancer cells. Therefore researchers started to give attention to identification of methodologies and strategies to overcome the stumbling blocks associated with TRAIL-based therapeutics. Subsequent studies gave us a clear picture of signaling cascade of TRAIL and how deregulation of different proteins abrogated apoptosis. In this chapter we have attempted to provide an overview of the TRAIL induced signaling, list of proteins frequently deregulated and modern approaches to strategically restore apoptosis in TRAIL-resistant breast cancers.

Crystal structures of human 17β-hydroxysteroid dehydrogenase type 1 complexed with estrone and NADP+ reveal the mechanism of substrate inhibition

Human 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1) catalyses the last step in estrogen activation and is thus involved in estrogen-dependent diseases (EDDs). Unlike other 17β-HSD members, 17β-HSD1 undergoes a significant substrate-induced inhibition that we have previously reported. Here we solved the binary and ternary crystal structures of 17β-HSD1 in complex with estrone (E1) and cofactor analog NADP⁺ , demonstrating critical enzyme-substrate-cofactor interactions. These complexes revealed a reversely bound E1 in 17β-HSD1 that provides the basis of the substrate inhibition, never demonstrated in estradiol complexes. Structural analysis showed that His²²¹ is the key residue responsible for the reorganization and stabilization of the reversely bound E1, leading to the formation of a dead-end complex, which exists widely in NADP(H)-preferred enzymes for the regulation of their enzymatic activity. Further, a new inhibitor is proposed that may inhibit 17β-HSD1 through the formation of a dead-end complex. This finding indicates a simple mechanism of enzyme regulation in the physiological background and introduces a pioneer inhibitor of 17β-HSD1 based on the dead-end inhibition model for efficiently targeting EDDs. DATABASES: Coordinates and structure factors of 17β-HSD1-E1 and 17β-HSD1-E1-NADP⁺ have been deposited in the Protein Data Bank with accession code 6MNC and 6MNE respectively. ENZYMES: 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1) EC 1.1.1.62.

The dual sex hormone specificity for human reductive 17β-hydroxysteroid dehydrogenase type 7: Synergistic function in estrogen and androgen control

Human 17β-hydroxysteroid dehydrogenase (17β-HSD) type 1 and 7 catalyze the final step of estrogen activation and the first step in androgen inactivation. It has been shown in breast cancer cells that DHT has a suppression effect on cell proliferation, counteracting the estrogen growth effect. However, the exact kinetic function of 17β-HSD7 in steroidogenesis was not determined. Here we report the steady-state kinetics and binding study for 17β-HSD7 with estrone or DHT as substrates and NADPH as cofactor. 17β-HSD7 has been overexpressed in E. coli and purified. For both substrates, kinetics of 17β-HSD7 demonstrates positive cooperativity. The K_0.5 value is 5.2 ± 0.4 μM and 14.4 ± 0.8 μM and the k_cat is 0.0063 ± 0.0003 s^-1 and 0.0153 ± 0.0007 s^-1 for the reduction of E1 and DHT, respectively. The binding study shows a similar affinity with a dissociation constant of 5.2 ± 0.5 μM and 11 ± 1 μM for E1 and DHT, respectively. Our kinetic and binding results reveal a positive cooperativity for 17β-HSD7 to both the E1 and DHT with a similar affinity, while 17β-HSD1 demonstrated a significantly higher affinity toward E1 than DHT, but with a strong E1 substrate inhibition. These results strongly support that the inhibition of 17β-HSD7 constitutes the basis of breast cancer cell proliferation decreasing that led to the shrinkage of xenograft ER + breast tumor mice model.

Synthesis of substituted 15β-alkoxy estrone derivatives and their cofactor-dependent inhibitory effect on 17β-HSD1

17β-Hydroxysteroid dehydrogenase type 1 (17β-HSD1) is a key enzyme in the biosynthesis of 17β-estradiol. Novel estrone-based compounds bearing various 15β-oxa-linked substituents and hydroxy, methoxy, benzyloxy, and sulfamate groups in position C3 as potential 17β-HSD1 inhibitors have been synthesized. In addition, in vitro inhibitory potentials measured in the presence of excess amount of NADPH or NADH were investigated. We observed substantial inhibitory potentials for several derivatives (IC₅₀ < 1 µM) and increased binding affinities compared to unsubstituted core molecules. Binding and inhibition were found to be cofactor-dependent for some of the compounds and we propose structural explanations for this phenomenon. Our results may contribute to the development of new 17β-HSD1 inhibitors, potential drug candidates for antiestrogen therapy of hormone-dependent gynecological cancers.

Steroid sulfatase inhibition success and limitation in breast cancer clinical assays: An underlying mechanism

Steroid sulfatase is detectable in most hormone-dependent breast cancers. STX64, an STS inhibitor, induced tumor reduction in animal assay. Despite success in phase І clinical trial, the results of phase II trial were not that significant. Breast Cancer epithelial cells (MCF-7 and T47D) were treated with two STS inhibitors (STX64 and EM1913). Cell proliferation, cell cycle, and the concentrations of estradiol and 5α-dihydrotestosterone were measured to determine the endocrinological mechanism of sulfatase inhibition. Comparisons were made with inhibitions of reductive 17β-hydroxysteroid dehydrogenases (17β-HSDs). Proliferation studies showed that DNA synthesis in cancer cells was modestly decreased (approximately 20%), accompanied by an up to 6.5% in cells in the G0/G1 phase and cyclin D1 expression reduction. The concentrations of estradiol and 5α-dihydrotestosterone were decreased by 26% and 3% respectively. However, supplementation of 5α-dihydrotestosterone produced a significant increase (approximately 35.6%) in the anti-proliferative effect of sulfatase inhibition. This study has clarified sex-hormone control by sulfatase in BC, suggesting that the different roles of estradiol and 5α-dihydrotestosterone can lead to a reduction in the effect of sulfatase inhibition when compared with 17β-HSD7 inhibition. This suggests that combined treatment of sulfatase inhibitors with 17β-HSD inhibitors such as the type7 inhibitor could hold promise for hormone-dependent breast cancer.

Development and Evaluation of Antibody Proteomics Technology for Rapid and Comprehensive Identification of Potential Biomarkers and Therapeutic Targets

Proteomics-based analyses are powerful means of identifying potentially useful proteins in the initial stage of drug development. Technological developments in the field of proteomics, and increases in the sensitivity of MS analyses, now facilitate identification and examination of increasingly small amounts of proteins that are differentially expressed in diseased versus normal tissues and can be candidate biomarkers or therapeutic targets. However, the current approach is for candidate proteins to be prioritized by research interest and then validated one by one; this is very inefficient. To address this issue, we have developed what we refer to as "antibody proteomics technology," which uses a phage antibody library and tissue microarray analysis to rapidly and comprehensively isolate monoclonal antibodies against candidate proteins for the identification of potential biomarkers and therapeutic targets. In our validation of this technology, we successfully identified oxysterol binding protein-like 5 and calumenin as potential biomarkers related to metastasis in lung cancer, annexin A4 as a potential biomarker related to cisplatin resistance in malignant mesothelioma, and Eph receptor A10 as a potential therapeutic target in breast cancer, including refractory breast cancer. These findings suggest that antibody proteomics technology has the potential to become a fundamental technology in drug discovery for the development of novel biomarkers and therapeutic targets.

Combined Biophysical Chemistry Reveals a New Covalent Inhibitor with a Low-Reactivity Alkyl Halide

17β-Hydroxysteroid dehydrogenase type 1 (17β-HSD1) plays a pivotal role in the progression of estrogen-related diseases because of its involvement in the biosynthesis of estradiol (E2), constituting a valuable therapeutic target for endocrine treatment. In the present study, we successfully cocrystallized the enzyme with the reversible inhibitor 2-methoxy-16β-( m-carbamoylbenzyl)-E2 (2-MeO-CC-156) as well as the enzyme with the irreversible inhibitor 3-(2-bromoethyl)-16β-( m-carbamoylbenzyl)-17β-hydroxy-1,3,5(10)-estratriene (PBRM). The structures of ternary complexes of 17β-HSD1-2-MeO-CC-156-NADP⁺ and 17β-HSD1-PBRM-NADP⁺ comparatively show the formation of a covalent bond between His²²¹ and the bromoethyl side chain of the inhibitor in the PBRM structure. A dynamic process including beneficial molecular interactions that favor the specific binding of a low-reactivity inhibitor and subsequent N-alkylation event through the participation of His²²¹ in the enzyme catalytic site clearly demonstrates the covalent bond formation. This finding opens the door to a new design of alkyl halide-based specific covalent inhibitors as potential therapeutic agents for different enzymes, contributing to the development of highly efficient inhibitors.

Antiproliferative Properties of Newly Synthesized 19-Nortestosterone Analogs Without Substantial Androgenic Activity

19-Nortestosterone C-17 epimers with prominent antiproliferative properties have been previously described. In our present study, five novel 17α-19-nortestosterones (3-7) were synthesized to increase their beneficial biological activities with no associated undesired hormonal effects. The compounds were screened by a viability assay against a panel of human adherent gynecological cancer cell lines. Three of the tested derivatives (3-5) exhibited a remarkable inhibitory effect on the proliferation of HeLa cells with IC₅₀ values lower than that of our reference agent cisplatin (CIS). These three active agents also displayed considerable cancer selectivity as evidenced by their weaker growth inhibitory effect on non-cancerous fibroblast cells compared to CIS. The most potent newly synthesized 17α-chloro derivative (3) was selected for additional experiments in order to characterize its mechanism of action. Since nandrolone (19-nortestosterone, 1) is a structural analog with selective antiproliferative action on cervical carcinoma cells, it was utilized as a positive control in these studies. A lactate dehydrogenase (LDH) assay demonstrated a moderate cytotoxic effect of the test compounds. Cell cycle disturbance and the elevation of the hypodiploid population elicited by the test agents were detected by flow cytometry following propidium staining. The proapoptotic effects of the tested steroids were confirmed by fluorescent microscopy and a caspase-3 activity assay. Treatment-related caspase-9 activation without a substantial change in caspase-8 activity indicates the induction of the intrinsic apoptotic pathway. The selected agents directly influence the rate of tubulin assembly as evidenced by a polymerization assay. Yeast-based reporter gene assay revealed that the androgenic activity of the novel 19-nortestosterone derivative 3 is by multiple orders of magnitude weaker than that of the reference agent 1. Based on the behavior of the examined compounds it can be concluded that a halogen substitution of the 19-nortestosterone scaffold at the 17α position may produce compounds with unique biological activities. The results of the present study support that structurally modified steroids with negligible hormonal activity are a promising basis for the research and development of novel anticancer agents.

[Development of a Fundamental Technology to Seek Drug Targets, and Its Application to Cancer Targeting Therapy]

　Human epidermal growth factor receptor 2 (Her2)-targeting antibodies and anti-hormone therapy are effective for most breast cancer patients. However, such approaches are not viable with resistant cases or in triple-negative breast cancer (TNBC) patients, given the lack of Her2 and estrogen and progesterone receptors in these patients. Thus, new drug targets are urgently required. From this perspective, we searched for novel drug targets using proteomic analysis, and identified Eph receptor A10 (EphA10), which is elevated in breast cancer cells as compared to normal breast tissue. Here, we evaluated the potential of EphA10 as a drug target by analyzing its protein expression profile/function in cancer cells, and then by using an anti-EphA10 antibody to treat EphA10-expressing tumor-bearing mice. Protein expression profile analysis showed that EphA10 was expressed in various breast cancer subtypes, including TNBCs, with no expression observed in normal tissues, apart from the testes. Moreover, functional analysis of the cancer cells revealed that ligand-dependent proliferation was observed in EphA10-expressed cancer cells. Thus, we developed our novel anti-EphA10 antibody, which binds to EphA10 with high specificity and affinity at the nanomolar level. Finally, therapeutic analysis indicated that tumor growth was significantly suppressed in the mAb-treated mice in a dose-dependent manner. These results suggest that the EphA10-targeting therapy may be a novel therapeutic option for the management of breast cancer, including in TNBCs which aren't currently treated with molecular-targeted agents. Consequently, we hope that these findings will contribute to the development of a new targeting therapy for refractory breast cancer patients.

Natural scaffolds in anticancer therapy and precision medicine

The diversity of natural compounds is essential for their mechanism of action. The source, structures and structure activity relationship of natural compounds contributed to the development of new classes of chemotherapy agents for over 40 years. The availability of combinatorial chemistry and high-throughput screening has fueled the challenge to identify novel compounds that mimic nature's chemistry and to predict their macromolecular targets. Combining conventional and targeted therapies helped to successfully overcome drug resistance and prolong disease-free survival. Here, we aim to provide an overview of preclinical investigated natural compounds alone and in combination to further improve personalization of cancer treatment.

Expansion of tumor-infiltrating lymphocytes and their potential for application as adoptive cell transfer therapy in human breast cancer

Adoptive cell transfer (ACT) of ex vivo expanded tumor-infiltrating lymphocytes (TILs) has been successful in treating a considerable proportion of patients with metastatic melanoma. In addition, some patients with several other solid tumors were recently reported to have benefited clinically from such ACT. However, it remains unclear whether ACT using TILs is broadly applicable in breast cancer, the most common cancer in women. In this study, the utility of TILs as an ACT source in breast cancers was explored by deriving TILs from a large number of breast cancer samples and assessing their biological potentials. We successfully expanded TILs ex vivo under a standard TIL culture condition from over 100 breast cancer samples, including all breast cancer subtypes. We also found that the information about the percentage of TIL and presence of tertiary lymphoid structure in the tumor tissues could be useful for estimating the number of obtainable TILs after ex vivo culture. The ex vivo expanded TILs contained a considerable level of central memory phenotype T cells (about 20%), and a large proportion of TIL samples were reactive to autologous tumor cells in vitro. Furthermore, the in vitro tumor-reactive autologous TILs could also function in vivo in a xenograft mouse model implanted with the primary tumor tissue. Collectively, these results strongly indicate that ACT using ex vivo expanded autologous TILs is a feasible option in treating patients with breast cancer.

Substrate inhibition of 17β-HSD1 in living cells and regulation of 17β-HSD7 by 17β-HSD1 knockdown

This study addresses first the role of human 17β-hydroxysteroid dehydrogenase type 1 (17β-HSD1) in breast cancer (BC) cells. The enzyme has a high estrone-activating activity that is subject to strong substrate inhibition as shown by enzyme kinetics at the molecular level. We used BC cells to verify this phenomenon in living cells: estrone concentration increase did reduce the reaction with 0.025 to 4μM substrate. Moreover, 5α-dihydrotestosterone (DHT) demonstrated some inhibition of estrogen activation at both the molecular and cellular levels. The presence of DHT did not change the tendency toward substrate inhibition for estrone conversion, but shifted the inhibition toward higher substrate concentrations. Moreover, a binding study demonstrated that both DHT and dehydroepiandrosterone (DHEA) can be bound to the enzyme, thereby supporting the multi-specificity of 17β-HSD1. We then followed the concentrations of estradiol and performed q-RT-PCR measurements of reductive 17β-HSDs after 17β-HSD1 inhibition. The estradiol decrease by the 17β-HSD1 inhibition was demonstrated lending support to this observation. Knockdown and inhibition of 17β-HSD1 produced reduction in estradiol levels and the down-regulation of another reductive enzyme 17β-HSD7, thus "amplifying" the reduction of estradiol by the 17β-HSD1 modulation itself. The critical positioning of 17β-HSD7 in sex-hormone-regulation as well as the mutual regulation of steroid enzymes via estradiol in BC, are clearly demonstrated. Our study demonstrates that fundamental enzymological mechanisms are relevant in living cells. Moreover, further enzyme study in cells is merited to advance biological and medical research. We also demonstrated the central role of 17β-HSD7 in sex-hormone conversion and regulation, supporting it as a novel target for estrogen-dependent (ER+) BC.

Inhibition of 17beta-hydroxysteroid dehydrogenase type 7 modulates breast cancer protein profile and enhances apoptosis by down-regulating GRP78

17beta-hydroxysteroid dehydrogenase type 7 (17β-HSD7) promotes breast cancer cell growth via dual-catalytic activity by modulating estradiol and DHT. Here, we clarified the expression pattern of 17β-HSD7 in postmenopausal luminal A type breast cancer with The Cancer Genome Atlas (TCGA) cohort. The impact of 17β-HSD7 inhibition on the proteome of MCF-7 cells was investigated and on cell apoptosis was revealed. MCF-7 cells were treated with an efficient inhibitor of 17β-HSD7 (INH7) or with vehicle, and a differential proteomics study was performed using two-dimensional (2D) gel electrophoresis followed by mass spectrometry and ingenuity pathway analysis (IPA). Cell apoptosis was analyzed by flow cytometry, followed by reverse transcription quantitative real-time PCR (RT-qPCR) and Western blot to investigate the expression of apoptosis-related genes. Our data showed 17β-HSD7 is amplified in primary and progressive breast cancer, inhibition of 17β-HSD7 in MCF-7 cells modulated 104 proteins primarily involved in cell death/survival, cell growth and DNA processing. The expression of 78kDa glucose-regulated protein (GRP78) and anti-apoptosis factor Bcl-2 were significantly suppressed via 17β-HSD7 inhibition with INH7, consequently induced MCF-7 cell apoptosis. However, INH7 treatment of T47D, another widely used epithelial ER+ breast cancer cell line, led to an up-regulation of GRP78 expression, resulting in a limited increase in apoptosis. These results suggest cell-specific effects of INH7 in the breast cancer, which is interesting for further study. An combinatory effect on apoptosis by INH7 and Letrozole (aromatase inhibitor) was further demonstrated in MCF-7. Down-regulation of GRP78 via 17β-HSD7 inhibition enhances cell apoptosis in response to Letrozole. This study highlights GRP78 as a key regulator related to 17β-HSD7 inhibition and effect. Taken together, results from the present study suggest a hypothesis that inhibition of 17β-HSD7 would be a complementary strategy to Letrozole by suppression of GRP78 in ER+ breast cancer. However, from a research perspective, further studies have to be carried out with more breast cancer cell lines as well as in vivo model to assess the efficacy of inhibitor combination.

Synergistic anti-cancer effects of epigenetic drugs on medulloblastoma cells

PURPOSE

Medulloblastomas are aggressive brain malignancies. While considerable progress has been made in the treatment of medulloblastoma patients with respect to overall survival, these patients are still at risk of developing neurologic and cognitive deficits as a result of anti-cancer therapies. It is hypothesized that targeted molecular therapies represent a better treatment option for medulloblastoma patients. Therefore, the aim of the present study was to test a panel of epigenetic drugs for their effect on medulloblastoma cells under mild hypoxic conditions that reflect the physiological concentrations of oxygen in the brain.

METHODS

Protein levels of histone deacetylase 1 (HDAC1) and DNA methyltransferase 1 (DNMT1) in medulloblastoma-derived cells (Daoy and D283 Med), as well as in developing and differentiated brain cells, were determined and compared. Class I and II histone deacetylase inhibitors (HDACi) and a DNMT inhibitor, 5-aza-2'-deoxycytidine (5-aza-dC), were applied to Daoy and D283 Med cells, and their effects were studied using viability, apoptosis and cancer sphere assays.

RESULTS

We found that in HDAC1 and DNMT1 overexpressing medulloblastoma-derived cells, cell death was induced under various epigenetic drug conditions tested. At low HDACi concentrations, however, a pro-proliferative effect was observed. Parthenolide, a drug that affects cancer stem cells, was found to be efficient in inducing cell death in both cell lines tested. In contrast, we found that Daoy cells were more resistant to 5-aza-dC than D283 Med cells. When suberoylanilide hydroxamic acid (SAHA) and parthenolide were individually applied to both cell lines in combination with 5-aza-dC, a synergistic effect on cell survival was observed.

CONCLUSIONS

Our current results suggest that the application of HDACi in combination with drugs that target DNMT may represent a promising option for the treatment of medulloblastoma.

Clinical significance of the estrogen-modifying enzymes steroid sulfatase and estrogen sulfotransferase in epithelial ovarian cancer

17β-estradiol (E2) can contribute to the progression of epithelial ovarian cancer (EOC). Although the majority of patients with EOC are postmenopausal woman, when de novo estrogen production in the ovary has ceased, ovarian cancer cells remain exposed to estrogens synthesized locally in the cancer cells from inactive sulfonated steroid hormone precursors-such as estrone sulfate taken up from the circulation via the sulfatase pathway. An abundance of the estrogen-modifying enzymes, including estrogen-activating steroid sulfatase (STS) and estrogen-inactivating estrogen-sulfotransferase (SULT1E1), is important for providing active estrogen to EOC cells. Therefore, the present study determined the levels of SULT1E1, STS and estrogen receptor α (ERα) protein in paraffin-embedded specimens from 206 patients with Federation of Gynecology and Obstetrics stage II–IV EOC treated with debulking surgery and standard platinum-based adjuvant chemotherapy. The levels of STS, SULT1E1 and ERα were assessed by automated quantitative microscopy-based image analysis subsequent to immunohistochemical staining. Significantly higher SULT1E1 levels were observed in better differentiated EOC tumors compared to grade 3 EOC tumors (P=0.001). STS and SULT1E1 levels were positively associated with ERα abundance (P<0.001 and P=0.001, respectively). In advanced stage high-grade serous EOC (HGSOC; n=132), the most frequent and lethal type of ovarian cancer, SULT1E1 expression was significantly associated with a better overall survival rate (hazard ratio 0.66, 95% confidence interval, 0.45–0.94; P=0.005). These results highlight the importance of SULT1E1-mediated estrogen inactivation in EOC, particularly HGSOC. Therefore, targeting the sulfatase pathway is a potential endocrine therapeutic intervention for certain patients with estrogen-responsive EOC.

Mechanism of Regulatory Effect of MicroRNA-206 on Connexin 43 in Distant Metastasis of Breast Cancer

Background:

MicroRNA-206 (miR-206) and connexin 43 (Cx43) are related with the distant metastasis of breast cancer. It remains unclear whether the regulatory effect of miR-206 on Cx43 is involved in metastasis of breast cancer.

Methods:

Using quantitative real-time polymerase chain reaction and Western blot, the expressions of miR-206 and Cx43 were determined in breast cancer tissues, hepatic and pulmonary metastasis (PM), and cell lines (MCF-10A, MCF-7, and MDA-MB-231). MCF-7/MDA-M-231 cells were transfected with lentivirus-shRNA vectors to enhance/inhibit miR-206, and then Cx43 expression was observed. Cell counting kit-8 assay and Transwell method were used to detect their changes in proliferation, migration, and invasion activity. The mutant plasmids of Cx43-3’ untranslated region (3’UTR) at position 478–484 and position 1609–1615 were constructed. Luciferase reporter assay was performed to observe the effects of miR-206 on luciferase expression of different mutant plasmids and to confirm the potential binding sites of Cx43.

Results:

Cx43 protein expression in hepatic and PM was significantly higher than that in the primary tumor, while no significant difference was showed in messenger RNA (mRNA) expression. MiR-206 mRNA expression in hepatic and PM was significantly lower than that in the primary tumor. Cx43 mRNA and protein levels, as well as cell proliferation, migration, and invasion capabilities, were all significantly improved in MDA-MB-231 cells after reducing miR-206 expression but decreased in MCF-7 cells after elevating miR-206 expression, which demonstrated a significantly negative correlation between miR-206 and Cx43 expression (P = 0.03). MiR-206 can drastically decrease Cx43 expression of MCF-7 cells but exerts no effects on Cx43 expression in 293 cells transfected with the Cx43 coding region but the lack of Cx43-3’UTR, suggesting that Cx43-3’UTR may be the key in Cx43 regulated by miR-206. Luciferase expression showed that the inhibition efficiency was reduced by 46.80% in position 478–484 mutant, 16.72% in position 1609–1615 mutant; the inhibition was totally disappeared in double mutant (P = 0.02).

Conclusions:

MiR-206 can regulate the expression of Cx43, the cytobiological activity, and the metastasis of breast cancer through binding to the two binding sites in Cx43-3’UTR: position 478–484 and position 1609–1615.

Estradiol-independent modulation of breast cancer transcript profile by 17beta-hydroxysteroid dehydrogenase type 1

17beta-hydroxysteroid dehydrogenase type 1 (17β-HSD1) is a steroidal enzyme which, in breast cancer cells, mainly synthesizes 17-beta-estradiol (E2), an estrogenic hormone that stimulates breast cancer cell growth. We previously showed that the enzyme increased breast cancer cell proliferation via a dual effect on E2 and 5α-dihydrotestosterone (DHT) levels and impacted gene expression and protein profile of breast cancer cells cultured in E2-contained medium. Here, we used RNA interference technique combined with microarray analyses to investigate the effect of 17β-HSD1 expression on breast cancer cell transcript profile in steroid-deprived condition. Our data revealed that knockdown of 17β-HSD1 gene, HSD17B1, modulates the transcript profile of the hormone-dependent breast cancer cell line T47D, with 105 genes regulated 1.5 fold or higher (p < 0.05) in estradiol-independent manner. Using Ingenuity Pathway Analysis (IPA), we additionally assessed functional enrichment analyses, including biological functions and canonical pathways, and found that, in concordance with the role of 17β-HSD1 in cancer cell growth, most regulated genes are cancer-related genes. Genes that primarily involved in the cell cycle progression, such as the cyclin A2 gene, CCNA2, are generally down-regulated whereas genes involved in apoptosis and cell death, including the pro-apoptotic gene XAF1, IFIH1 and FGF12, are on the contrary up-regulated by 17β-HSD1 knockdown, and 21% of the modulated genes belong to this latter functional category. This indicates that 17β-HSD1 may be involved in oncogenesis by favoring anti-apoptosis pathway in breast cancer cells and correborates with its previously shown role in increasing breast cancer cell proliferation. The gene regulation occurring in steroid-deprived conditions showed that 17β-HSD1 can modulate endogenous gene expression in steroid-independent manners. Besides, we tested the ability of estrogen to induce or repress endogenous genes of T47D by microarray analysis. Expression of a total of 130 genes were found to increase or decrease 1.5-fold or higher (p < 0.05) in response to E2 treatment (1 nM for 48 h), revealing a list of potential new estrogen-responsive genes and providing useful information for further studies of estrogen-dependent breast cancer mechanisms. In conclusion, in breast cancer cells, in addition to its implication in the E2-dependent gene transcription, the present study demonstrates that 17β-HSD1 also modulates gene expression via mechanisms independent of steroid actions. Those mechanisms that may include the ligand-independent gene transcription of estrogen receptor alpha (ERα), whose expression is positively correlated with that of the enzyme, and that may implicate 17β-HSD1 in anti-apoptosis pathways, have been discussed.

DNMT1-PPARγ pathway in macrophages regulates chronic inflammation and atherosclerosis development in mice

The DNA methyltransferase-mediated proinflammatory activation of macrophages is causally linked to the development of atherosclerosis (AS). However, the role of DNMT1, a DNA methylation maintenance enzyme, in macrophage polarization and AS development remains obscure. Here, we established transgenic mice with macrophage-specific overexpression of DNMT1 (Tg^DNMT1) or PPAR-γ (Tg^PPAR-γ) to investigate their effects on AS progression in ApoE-knockout mice fed an atherogenic diet. Primary macrophages were extracted to study the role of the DNMT1/PPAR-γ pathway in regulating inflammatory cytokine production. We demonstrated that Tg^DNMT1 significantly increased proinflammatory cytokine production in macrophages and plasma, and it accelerated the progression of AS in the atherogenic diet-treated ApoE-knockout mice. Further, we found that the DNA methylation status of the proximal PPAR-γ promoter was regulated by DNMT1 in macrophages. Notably, additional Tg^PPAR-γ or pharmacological activation of PPAR-γ effectively prevented Tg^DNMT1-induced proinflammatory cytokine production in macrophages and AS development in the mouse model. Finally, we demonstrated that elevated DNMT1 was correlated with decreased PPAR-γ, and increased proinflammatory cytokine production in the peripheral blood monocytes isolated from the patients with AS, compared to those of healthy donors. Our findings shed light on a novel strategy for the prevention and therapy of AS.

Mimicking postmenopausal steroid metabolism in breast cancer cell culture: Differences in response to DHEA or other steroids as hormone sources

Following menopause virtually 100% of estrogens are synthesized in peripheral target tissues from precursor steroids of adrenal origin. These steroids are the unique source of sex steroids in these women. This positions some steroid metabolizing enzymes as primary targets for novel therapies for estrogen receptor-positive (ER+) breast cancer. However, previous research on the steroid-converting enzymes has been performed using their direct substrate as a hormone source, depending on the facility where studied and the robust signal obtained. These experiments may not always provide an accurate reflection of physiological and post-menopausal conditions. We suggest providing dehydroepiandrosterone (DHEA) as an intracrinological hormone source, and comparing the role of steroid-converting enzymes using DHEA and their direct substrates when an extensive mechanistic understanding is required. Here, we present a comparative study of these enzymes with the provision of DHEA and the direct substrates, estrone (E1) or dihydrotestosterone (DHT), or additional steroids as hormone sources, in breast cancer cells. Enzyme knockdown by respective specific siRNAs and observations on the resulting differences in biological function were carried out. Cell biology studies showed no difference in biological function for 17β-HSD1 and 17β-HSD7 when cultured with different steroid hormones: cell proliferation and estradiol levels decreased, whereas DHT accumulated; cyclinD1, PCNA, and pS2 were down-regulated after knocking down these two enzymes, although the quantitative results varied. However, culture medium supplementation was found to have a marked impact on the study of 3α-HSD3. We demonstrated that provision of different steroids as a substrate or hormone sources may promote modified biological effects: provision of DHEA is the preferred choice to mimic postmenopausal steroid metabolism in cell culture.

Inhibition of Macrophage CD36 Expression and Cellular Oxidized Low Density Lipoprotein (oxLDL) Accumulation by Tamoxifen: A PEROXISOME PROLIFERATOR-ACTIVATED RECEPTOR (PPAR)γ-DEPENDENT MECHANISM

Macrophage CD36 binds and internalizes oxidized low density lipoprotein (oxLDL) to facilitate foam cell formation. CD36 expression is activated by peroxisome proliferator-activated receptor γ (PPARγ). Tamoxifen, an anti-breast cancer medicine, has demonstrated pleiotropic functions including cardioprotection with unfully elucidated mechanisms. In this study, we determined that treatment of ApoE-deficient mice with tamoxifen reduced atherosclerosis, which was associated with decreased CD36 and PPARγ expression in lesion areas. At the cellular level, we observed that tamoxifen inhibited CD36 protein expression in human THP-1 monocytes, THP-1/PMA macrophages, and human blood monocyte-derived macrophages. Associated with decreased CD36 protein expression, tamoxifen reduced cellular oxLDL accumulation in a CD36-dependent manner. At the transcriptional level, tamoxifen decreased CD36 mRNA expression, promoter activity, and the binding of the PPARγ response element in CD36 promoter to PPARγ protein. Tamoxifen blocked ligand-induced PPARγ nuclear translocation and CD36 expression, but it increased PPARγ phosphorylation, which was due to that tamoxifen-activated ERK1/2. Furthermore, deficiency of PPARγ expression in macrophages abolished the inhibitory effect of tamoxifen on CD36 expression or cellular oxLDL accumulation both in vitro and in vivo Taken together, our study demonstrates that tamoxifen inhibits CD36 expression and cellular oxLDL accumulation by inactivating the PPARγ signaling pathway, and the inhibition of macrophage CD36 expression can be attributed to the anti-atherogenic properties of tamoxifen.

Discovery of a sulfamate-based steroid sulfatase inhibitor with intrinsic selective estrogen receptor modulator properties

Steroid sulfatase (STS), the enzyme which converts inactive sulfated steroid precursors into active hormones, is a promising therapeutic target for the treatment of estrogen-sensitive breast cancer. We report herein the synthesis and in vitro study of dual-action STS inhibitors with selective estrogen-receptor modulator (SERM) effects. A library of tetrahydroisoquinoline-N-substituted derivatives (phenolic compounds) was synthesized by solid-phase chemistry and tested on estrogen-sensitive breast cancer T-47D cells. Three phenolic compounds devoid of estrogenic activity and toxicity emerged from this screening. Their sulfamate analogs were then synthesized, tested in STS-transfected HEK-293 cells, and found to be potent inhibitors of the enzyme (IC50 of 3.9, 8.9, and 16.6 nM). When tested in T-47D cells they showed no estrogenic activity and produced a moderate antiestrogenic activity. The compounds were further tested on osteoblast-like Saos-2 cells and found to significantly stimulate their proliferation as well as their alkaline phosphatase activity, thus suggesting a SERM activity. These results are supported by molecular docking experiments.

Genetics and Breast Cancer - Oncologists Perspectives

Breast cancer is the most common cancer in women worldwide. The clinical outcomes of which, have improved in the past decade, primarily due early diagnosis and multimodal management. Understanding of the disease biology with findings from omics-based research and molecular genetic characterization of the disease has been an important component of the therapy in the past 10 years. There is a need to understand the variations in individuals at the molecular level to enable in sub-classification of the different disease phenotypes and if possible to tailor the treatment to the patient. This article attempts to review the beneficial role of genetics in various facets of breast cancer management, in modern scientific medicine.