FoxM1 is a downstream target and marker of HER2 overexpression in breast cancer

Unravelling the therapeutic potential of forkhead box proteins in breast cancer: An update (Review)

Breast cancer, a prominent cause of mortality among women, develops from abnormal growth of breast tissue, thereby rendering it one of the most commonly detected cancers in the female population. Although numerous treatment strategies are available for breast cancer, discordance in terms of effective treatment and response still exists. Recently, the potential of signaling pathways and transcription factors has gained substantial attention in the cancer community; therefore, understanding their role will assist researchers in comprehending the onset and advancement of breast cancer. Forkhead box (FOX) proteins, which are important transcription factors, are considered crucial regulators of various cellular activities, including cell division and proliferation. The present study explored several subclasses of FOX proteins and their possible role in breast carcinogenesis, followed by the interaction between microRNA (miRNA) and FOX proteins. This interaction is implicated in promoting cell infiltration into surrounding tissues, ultimately leading to metastasis. The various roles that FOX proteins play in breast cancer development, their intricate relationships with miRNA, and their involvement in therapeutic resistance highlight the complexity of breast cancer dynamics. Therefore, recognizing the progress and challenges in current treatments is crucial because, despite advancements, persistent disparities in treatment effectiveness underscore the need for ongoing research, with future studies emphasizing the necessity for targeted strategies that account for the multifaceted aspects of breast cancer.

Exploring Anticancer Properties of Medicinal Plants against Breast Cancer by Downregulating Human Epidermal Growth Factor Receptor 2

Plants have a history of being employed in managing breast cancer. However, no scientific evidence supports the idea that these plants can effectively reduce the level of HER2 expression. In this study, extracts from 10 medicinal plants were evaluated for their anticancer properties against HER2-positive breast cancer cells through various methods, including the SRB assay, comet assay, annexin V-FITC dual staining, and immunoblotting. All extracts exerted antiproliferative activity against HER2-positive breast cancer cells. Furthermore, Terminalia chebula (T. chebula), Berberis aristata (B. aristata), and Mucuna pruriens (M. pruriens) reduced HER2 expression in tested cell lines. In addition, an increased Bax/Bcl-2 ratio was observed after the treatment. A comparative proteomics study showed modulation in the proteome profile of breast cancer cells after treatment with T. chebula, B. aristata, Punica granatum, M. pruriens, and Acorus calamus. Metabolic profiling of lead plants revealed the existence of multiple anticancer compounds. Our study demonstrates the considerable potential of the mentioned plants as innovative therapies for HER2-positive breast cancer.

Predicting the molecular mechanism-driven progression of breast cancer through comprehensive network pharmacology and molecular docking approach

Identification of key regulators is a critical step toward discovering biomarker that participate in BC. A gene expression dataset of breast cancer patients was used to construct a network identifying key regulators in breast cancer. Overexpressed genes were identified with BioXpress, and then curated genes were used to construct the BC interactome network. As a result of selecting the genes with the highest degree from the BC network and tracing them, three of them were identified as novel key regulators, since they were involved at all network levels, thus serving as the backbone. There is some evidence in the literature that these genes are associated with BC. In order to treat BC, drugs that can simultaneously interact with multiple targets are promising. When compared with single-target drugs, multi-target drugs have higher efficacy, improved safety profile, and are easier to administer. The haplotype and LD studies of the FN1 gene revealed that the identified variations rs6707530 and rs1250248 may both cause TB, and endometriosis respectively. Interethnic differences in SNP and haplotype frequencies might explain the unpredictability in association studies and may contribute to predicting the pharmacokinetics and pharmacodynamics of drugs using FN1.

Targeting the oncogenic transcription factor FOXM1 to improve outcomes in all subtypes of breast cancer

FOXM1 (Forkhead box M1) is an oncogenic transcription factor that is greatly upregulated in breast cancer and many other cancers where it promotes tumorigenesis, and cancer growth and progression. It is expressed in all subtypes of breast cancer and is the factor most associated with risk of poor patient survival, especially so in triple negative breast cancer (TNBC). Thus, new approaches to inhibiting FOXM1 and its activities, and combination therapies utilizing FOXM1 inhibitors in conjunction with known cancer drugs that work together synergistically, could improve cancer treatment outcomes. Targeting FOXM1 might prove especially beneficial in TNBC where few targeted therapies currently exist, and also in suppressing recurrent advanced estrogen receptor (ER)-positive and HER2-positive breast cancers for which treatments with ER or HER2 targeted therapies that were effective initially are no longer beneficial. We present these perspectives and future directions in the context of what is known about FOXM1, its regulation, and its key roles in promoting cancer aggressiveness and metastasis, while being absent or very low in most normal non-regenerating adult tissues. We discuss new inhibitors of FOXM1 and highlight FOXM1 as an attractive target for controlling drug-resistant and difficult-to-suppress breast cancers, and how blocking FOXM1 might improve outcomes for patients with all subtypes of breast cancer.

LncRNA ZNF582-AS1 Expression and Methylation in Breast Cancer and Its Biological and Clinical Implications

Background: Long non-coding RNAs (lncRNAs) play an important role in cellular activities and functions, but our understanding of their involvement in cancer is limited. Methods: TCGA data on RNA expression and DNA methylation were analyzed for lncRNAs' association with breast cancer survival, using the Cox proportional hazard regression model. Fresh tumor samples and clinical information from 361 breast cancer patients in our study were used to confirm the TCGA finding on ZNF582-AS1. A RT-qPCR method was developed to measure ZNF582-AS1 expression. Survival associations with ZNF582-AS1 were verified with a meta-analysis. In silico predictions of molecular targets and cellular functions of ZNF582-AS1 were performed based on its molecular signatures and nucleotide sequences. Results:ZNF582-AS1 expression was lower in breast tumors than adjacent normal tissues. Low ZNF582-AS1 was associated with high-grade or ER-negative tumors. Patients with high ZNF582-AS1 had a lower risk of relapse and death. These survival associations were confirmed in a meta-analysis and remained significant after adjustment for tumor grade, disease stage, patient age, and hormone receptor status. Correlation analysis indicated the possible suppression of ZNF582-AS1 expression by promoter methylation. Bioinformatics interrogation of molecular signatures suggested that ZNF582-AS1 could suppress tumor cell proliferation via downregulating the HER2-mediated signaling pathway. Analysis of online data also suggested that HIF-1-related transcription factors could suppress ZNF582-AS1 expression, and the lncRNA might bind to hsa-miR-940, a known oncogenic miRNA in breast cancer. Conclusions: ZNF582-AS1 may play a role in suppressing breast cancer progression. Elucidating the lncRNA's function and regulation may improve our understanding of the disease.

Endocrine resistant breast cancer: brain metastasis

Endocrine resistant breast cancer metastasis continues to serve as a significant clinical challenge with high morbidity and mortality for patients. As the number of breast cancer cases continues to rise, the rate of brain metastasis has also increased. For single lesions or a large symptomatic lesion with other smaller lesions, surgical resection is a viable option in non-eloquent regions. Stereotactic radiosurgery is a great option for post-operative therapy or for 10 or fewer small lesions (< 3 cm in size). Whole-brain radiation can be used sparingly for large tumor burdens but should encompass hippocampus sparing techniques. Chemotherapy options have remained relatively limited due to decreased permeability of the blood-brain barrier. Emerging monoclonal antibody treatments have offered initial promise, especially for endocrine resistant breast cancer metastasis.

Forkhead Box Protein M1 Promotes Nasopharyngeal Carcinoma Cell Tumorigenesis Possibly via the Wnt/β-Catenin Signaling Pathway

BACKGROUND Forkhead box protein M1 (FoxM1) is an important transcription factor involved in the development and progression of various malignancies. However, its role in nasopharyngeal carcinoma (NPC) remains largely unknown. This study aimed to assess the effect of FoxM1 on NPC cell tumorigenesis as well as the underlying mechanism. MATERIAL AND METHODS NPC cell lines CNE-1 and CNE-2 were treated with vehicle and FoxM1 inhibitor thiostrepton or transfected with small interfering RNA. CCK-8 assay, flow cytometric assay, and Hoechst 33258 staining were performed to assess the viability, apoptosis and nuclear morphological impairment, and cell cycle, respectively. The expression of apoptosis-related caspase-3 and caspase-9 was detected by western blot analysis The tumor growth in the mouse xenograft model of NPC treated with thiostrepton or control was assessed. The expression of Wnt/ß-catenin signaling proteins p27, FoxM1, S phase kinase-associated protein 2 (SKP2), and Cyclin D1 were determined both in cells and xenograft tissues by western blot analysis. RESULTS Inhibition of FoxM1 by thiostrepton significantly suppressed NPC cell viability, induced apoptosis, increased cell cycle arrest, impaired nuclear morphology, and reduced NPC cell-derived tumor xenograft growth. Mechanistically, inhibition or knockdown of FoxM1 inactivated the Wnt/ß-catenin signaling pathway, as demonstrated by altered expression of Wnt/ß-catenin signaling-related genes, including p27, SKP2, and cyclin D1, in both NPC cells and xenograft tissues. CONCLUSIONS We identified FoxM1 as a novel regulator of NPC cell tumorigenesis in vitro and in vivo. Targeting FoxM1 could be a promising therapeutic strategy against NPC.

The Synergistic Effects of SHR6390 Combined With Pyrotinib on HER2+/HR+ Breast Cancer

HER2+/HR+ breast cancer is a special molecular type of breast cancer. Existing treatment methods are prone to resistance; “precision treatment” is necessary. Pyrotinib is a pan-her kinase inhibitor that can be used in HER2-positive tumors, while SHR6390 is a CDK4/6 inhibitor that can inhibit ER+ breast cancer cell cycle progression and cancer cell proliferation. In cancer cells, HER2 and CDK4/6 signaling pathways could be nonredundant; co-inhibition of both pathways by combination of SHR6390 and pyrotinib may have synergistic anticancer activity on HER2+/HR+ breast cancer. In this study, we determined the synergy of the two-drug combination and underlying molecular mechanisms. We showed that the combination of SHR6390 and pyrotinib synergistically inhibited the proliferation, migration, and invasion of HER2+/HR+ breast cancer cells in vitro. The combination of two drugs induced G1/S phase arrest and apoptosis in HER2+/HR+ breast cancer cell lines. The combination of two drugs prolonged the time to tumor recurrence in the xenograft model system. By second-generation RNA sequencing technology and enrichment analysis of the pyrotinib-resistant cell line, we found that FOXM1 was associated with induced resistance to HER2-targeted therapy. In HER2+/HR+ breast cancer cell lines, the combination of the two drugs could further reduce FOXM1 phosphorylation, thereby enhancing the antitumor effect to a certain extent. These findings suggest that SHR6390 combination with pyrotinib suppresses the proliferation, migration, and invasion of HER2+/HR+ breast cancers through regulation of FOXM1.

A narrative review of research progress on FoxM1 in breast cancer carcinogenesis and therapeutics

OBJECTIVE

The purpose of this review is to clarify the potential roles of forkhead box transcription factor M1 (FoxM1) in the occurrence and progression of breast cancer, as well as the predictive value of FoxM1 as a prognostic biomarker and potential therapeutic target for breast cancer.

BACKGROUND

Breast cancer, well-known as a molecularly heterogeneous cancer, is still one of the most frequently diagnosed malignant tumors among females worldwide. Tumor recurrence and metastasis are the central causes of high mortality in breast cancer patients. Many factors contribute to the occurrence and progression of breast cancer, including FoxM1. FoxM1, widely regarded as a classic proliferation-related transcription factor, plays pivotal roles in the occurrence, proliferation, invasion, migration, drug resistance, and epithelial-mesenchymal transition (EMT) processes of multiple human tumors including breast cancer.

METHODS

The PubMed database was searched for articles published in English from February 2008 to May 2021 using related keywords such as "forkhead box transcription factor M1", "human breast cancer", "FoxM1", and "human tumor". About 90 research papers and reports written in English were identified, most of which were published after 2015. These papers mainly concentrated on the functions of FoxM1 in the occurrence, development, drug resistance, and treatment of human breast cancer.

CONCLUSIONS

Considering that the abnormal expression of FoxM1 plays a significant role in the proliferation, invasion, metastasis, and chemotherapy drug resistance of breast cancer, and its overexpression is closely correlated with the unfavorable clinicopathological characteristics of breast tumor patients, it is considerably important to comprehend the regulatory mechanism of FoxM1 in breast cancer. This will provide strong evidence for FoxM1 as a potential biomarker for the targeted treatment and prognostic evaluation of breast cancer patients.

CDC2 Is an Important Driver of Vascular Smooth Muscle Cell Proliferation via FOXM1 and PLK1 in Pulmonary Arterial Hypertension

A key feature of pulmonary arterial hypertension (PAH) is the hyperplastic proliferation exhibited by the vascular smooth muscle cells from patients (HPASMC). The growth inducers FOXM1 and PLK1 are highly upregulated in these cells. The mechanism by which these two proteins direct aberrant growth in these cells is not clear. Herein, we identify cyclin-dependent kinase 1 (CDK1), also termed cell division cycle protein 2 (CDC2), as having a primary role in promoting progress of the cell cycle leading to proliferation in HPASMC. HPASMC obtained from PAH patients and pulmonary arteries from Sugen/hypoxia rats were investigated for their expression of CDC2. Protein levels of CDC2 were much higher in PAH than in cells from normal donors. Knocking down FOXM1 or PLK1 protein expression with siRNA or pharmacological inhibitors lowered the cellular expression of CDC2 considerably. However, knockdown of CDC2 with siRNA or inhibiting its activity with RO-3306 did not reduce the protein expression of FOXM1 or PLK1. Expression of CDC2 and FOXM1 reached its maximum at G1/S, while PLK1 reached its maximum at G2/M phase of the cell cycle. The expression of other CDKs such as CDK2, CDK4, CDK6, CDK7, and CDK9 did not change in PAH HPASMC. Moreover, inhibition via Wee1 inhibitor adavosertib or siRNAs targeting Wee1, Myt1, CDC25A, CDC25B, or CDC25C led to dramatic decreases in CDC2 protein expression. Lastly, we found CDC2 expression at the RNA and protein level to be upregulated in pulmonary arteries during disease progression Sugen/hypoxia rats. In sum, our present results illustrate that the increased expression of FOXM1 and PLK1 in PAH leads directly to increased expression of CDC2 resulting in potentiated growth hyperactivity of PASMC from patients with pulmonary hypertension. Our results further suggest that the regulation of CDC2, or associated regulatory proteins, will prove beneficial in the treatment of this disease.

FOXM1: A Multifunctional Oncoprotein and Emerging Therapeutic Target in Ovarian Cancer

Forkhead box M1 (FOXM1) is a member of the conserved forkhead box (FOX) transcription factor family. Over the last two decades, FOXM1 has emerged as a multifunctional oncoprotein and a robust biomarker of poor prognosis in many human malignancies. In this review article, we address the current knowledge regarding the mechanisms of regulation and oncogenic functions of FOXM1, particularly in the context of ovarian cancer. FOXM1 and its associated oncogenic transcriptional signature are enriched in >85% of ovarian cancer cases and FOXM1 expression and activity can be enhanced by a plethora of genomic, transcriptional, post-transcriptional, and post-translational mechanisms. As a master transcriptional regulator, FOXM1 promotes critical oncogenic phenotypes in ovarian cancer, including: (1) cell proliferation, (2) invasion and metastasis, (3) chemotherapy resistance, (4) cancer stem cell (CSC) properties, (5) genomic instability, and (6) altered cellular metabolism. We additionally discuss the evidence for FOXM1 as a cancer biomarker, describe the rationale for FOXM1 as a cancer therapeutic target, and provide an overview of therapeutic strategies used to target FOXM1 for cancer treatment.

Functional Characterization of Circulating Tumor Cells (CTCs) from Metastatic ER+/HER2- Breast Cancer Reveals Dependence on HER2 and FOXM1 for Endocrine Therapy Resistance and Tumor Cell Survival: Implications for Treatment of ER+/HER2- Breast Cancer

Simple Summary

Acquired endocrine resistance and late recurrence in patients with ER+/HER2− breast cancer are complex and not fully understood. Here, we evaluated mechanisms of acquired resistance in circulating tumor cells (CTCs) from an ER+/HER2− breast cancer patient who initially responded but later progressed under endocrine treatment. We found a switch from ERα-dependent to HER2-dependent and ERα-independent expression of FOXM1, which may enable disseminated ER+/HER2− cells to re-initiate tumor cell growth and metastasis formation in the presence of endocrine treatment. We found that NFkB signaling sustains HER2 and FOXM1 expression in CTCs in the presence of ERα inhibitors suggesting that NFkB and FOXM1 might be an efficient therapeutic approach to prevent late recurrence and to treat endocrine resistance. Collectively our data show that CTCs from patients with endocrine resistance allow mechanisms of acquired endocrine resistance to be delineated, and can be used to test potential drug regimens for combatting resistance.

Abstract

Mechanisms of acquired endocrine resistance and late recurrence in patients with ER+/HER2− breast cancer are complex and not fully understood. Here, we evaluated mechanisms of acquired resistance in circulating tumor cells (CTCs) from an ER+/HER2− breast cancer patient who initially responded but later progressed under endocrine treatment. We found a switch from ERα-dependent to HER2-dependent and ERα-independent expression of FOXM1, which may enable disseminated ER+/HER2− cells to re-initiate tumor cell growth and metastasis formation in the presence of endocrine treatment. Our results also suggest a role for HER2 in resistance, even in ER+ breast cancer cells that have neither HER2 amplification nor activating HER2 mutations. We found that NFkB signaling sustains HER2 and FOXM1 expression in CTCs in the presence of ERα inhibitors. Inhibition of NFkB signaling blocked expression of HER2 and FOXM1 in the CTCs, and induced apoptosis. Thus, targeting of NFkB and FOXM1 might be an efficient therapeutic approach to prevent late recurrence and to treat endocrine resistance. Collectively our data show that CTCs from patients with endocrine resistance allow mechanisms of acquired endocrine resistance to be delineated, and can be used to test potential drug regimens for combatting resistance.

FOXM1 and Cancer: Faulty Cellular Signaling Derails Homeostasis

Forkhead box transcription factor, FOXM1 is implicated in several cellular processes such as proliferation, cell cycle progression, cell differentiation, DNA damage repair, tissue homeostasis, angiogenesis, apoptosis, and redox signaling. In addition to being a boon for the normal functioning of a cell, FOXM1 turns out to be a bane by manifesting in several disease scenarios including cancer. It has been given an oncogenic status based on several evidences indicating its role in tumor development and progression. FOXM1 is highly expressed in several cancers and has also been implicated in poor prognosis. A comprehensive understanding of various aspects of this molecule has revealed its role in angiogenesis, invasion, migration, self- renewal and drug resistance. In this review, we attempt to understand various mechanisms underlying FOXM1 gene and protein regulation in cancer including the different signaling pathways, post-transcriptional and post-translational modifications. Identifying crucial molecules associated with these processes can aid in the development of potential pharmacological approaches to curb FOXM1 mediated tumorigenesis.

Transcriptomic analysis of the liver in aged laying hens with different intensity of brown eggshell color

OBJECTIVE

Eggshell color is an important indicator of egg quality for consumers, especially for brown eggs. Various factors related to laying hens and their environment affect brown eggshell coloration. However, there have been no studies investigating hepatic functions of laying hens with variable intensity of brown eggshell color. Therefore, this study was aimed to identify potential factors affecting brown eggshell coloration in aged laying hens at the hepatic transcriptomic level.

METHODS

Five hundred 92-wk-old Hy-line Brown laying hens were screened to select laying hens with different intensity of brown eggshell color based on eggshell color fans. Based on eggshell color scores, hens with dark brown eggshells (DBE; eggshell color fan score = 14.8) and hens with light brown eggshells (LBE; eggshell color fan score = 9.7) were finally selected for the liver sampling. We performed RNA-seq analysis using the liver samples through the paired-end sequencing libraries. Differentially expressed genes (DEGs) profiling was carried out to identify their biological meaning by bioinformatics.

RESULTS

A total of 290 DEGs were identified with 196 being up-regulated and 94 being down-regulated in DBE groups as compared to LBE groups. The Kyoto encyclopedia of genes and genomes (KEGG) analysis revealed that these DEGs belong to several biological pathways including herpes simplex infection (toll-like receptor 3 [TLR3], cyclin-dependent kinase 1, etc.) and influenza A (TLR3, radical S-adenosyl methionine domain containing 2, myxovirus [influenza virus] resistance 1, etc.). Genes related to stress response (ceremide kinase like) and nutrient metabolism (phosphoenolpyruvate carboxy-kinase 1, methylmalonic aciduria [cobalamin deficiency] cblB type, glycine receptor alpha 2, solute carrier family 7 member 11, etc.) were also identified to be differentially expressed.

CONCLUSION

The current results provide new insights regarding hepatic molecular functions related to different intensity of brown eggshell color in aged laying hens. These insights will contribute to future studies aiming to optimize brown eggshell coloration in aged laying hens.

EP300 and SIRT1/6 Co-Regulate Lapatinib Sensitivity Via Modulating FOXO3-Acetylation and Activity in Breast Cancer

Forkhead Box O3 (FOXO3) is a tumor suppressor whose activity is fine-tuned by post-translational modifications (PTMs). In this study, using the BT474 breast cancer cells and a recently established lapatinib resistant (BT474-Lap^R) cell line, we observed that higher FOXO3 and acetylated (Ac)-FOXO3 levels correlate with lapatinib sensitivity. Subsequent ectopic expression of EP300 led to an increase in acetylated-FOXO3 in sensitive but not in resistant cells. Drug sensitivity assays revealed that sensitive BT474 cells show increased lapatinib cytotoxicity upon over-expression of wild-type but not acetylation-deficient EP300. Moreover, FOXO3 recruitment to target gene promoters is associated with target gene expression and drug response in sensitive cells and the inability of FOXO3 to bind its target genes correlates with lapatinib-resistance in BT474-Lap^R cells. In addition, using SIRT1/6 specific siRNAs and chemical inhibitor, we also found that sirtuin 1 and -6 (SIRT1 and -6) play a part in fine-tuning FOXO3 acetylation and lapatinib sensitivity. Consistent with this, immunohistochemistry results from different breast cancer subtypes showed that high SIRT6/1 levels are associated with constitutive high FOXO3 expression which is related to FOXO3 deregulation/inactivation and poor prognosis in breast cancer patient samples. Collectively, our results suggest the involvement of FOXO3 acetylation in regulating lapatinib sensitivity of HER2-positive breast cancers.

Regulation of PERK expression by FOXO3: a vulnerability of drug-resistant cancer cells

The major impediment to effective cancer therapy has been the development of drug resistance. The tumour suppressive transcription factor FOXO3 promotes cell cycle arrest, senescence and cell death, and mediates the cytotoxic and cytostatic functions of cancer therapeutics. In consequence, FOXO3 is often downregulated as an adaptive response in cancer and particularly in chemotherapeutic drug-resistant cells. Consistently, we find that FOXO3 expression is attenuated in the drug-resistant MCF-7-Epi^R and MCF-7-Tax^R compared to the parental MCF-7 breast cancer cells. Using ChIP, short-interfering RNA (siRNA) knockdown, and overexpression assays as well as Foxo^1/3/4-/- MEFs, we establish the endoplasmic reticulum (ER)-stress defence modulator PERK (eIF2AK3) as a direct downstream transcriptional target of FOXO3. In agreement, there is also a positive correlation between FOXO3 and PERK expression at the protein and RNA levels in breast cancer patient samples. We uncover that PERK expression is downregulated but its activity constitutively elevated in the drug-resistant cells. With this in mind, we exploit this adaptive response of low FOXO3 and PERK expression, and high PERK activity in drug-resistant breast cancer cells and show that these drug-resistant cells are specifically sensitive to PERK inhibition. In support of this finding, we show that ectopic overexpression of FOXO3 can reduce the sensitivity of the resistant cells to the PERK inhibitor GSK2606414, while the Foxo^1/3/4-/- MEFs expressing lower levels of PERK are more sensitive to PERK inhibition compared to wild-type MEFs. PERK inhibitor-titration and -time course experiments showed that the drug-resistant cells, which express lower expression and higher activity levels of PERK, are more sensitive to the increasing concentrations of PERK inhibitor compared to parental MCF-7 cells. Our present work thus reveals a chemotherapeutic drug-resistant cancer cell vulnerability in PERK and suggests PERK as a potential target for cancer therapy, specifically in the context of drug-resistant cancers.

Epigenetically altered miR‑193a‑3p promotes HER2 positive breast cancer aggressiveness by targeting GRB7

Emerging evidence has demonstrated that microRNAs (miRNAs/miRs) have various biological functions in the development of human epidermal growth factor receptor 2 (HER2) positive breast cancer. The aim of the present study is to reveal the mechanism of miR‑193a‑3p inhibiting the progress of HER2 positive breast cancer. The expression of miR‑193a‑3p was evaluated by quantitative polymerase chain reaction (PCR). The methylation status of miR‑193a‑3p was evaluated by PCR and pyrosequencing analysis. Overexpression of miR‑193a‑3p and growth factor receptor bound protein 7 (GRB7) combined with in vitro tumorigenic assays were conducted to determine the carcinostatic capacities of miR‑193a‑3p in HER2 positive breast cancer cells. The association between miR‑193a‑3p and GRB7 was determined by luciferase reporter assay. Protein level was evaluated using western blot analysis. miR‑193a‑3p was downregulated in HER2 positive breast cancer cells and clinical tissues. Methylation‑mediated silencing led to decreased expression of miR‑193a‑3p in HER2 positive breast cancer. Overexpression of miR‑193a‑3p could inhibit proliferation, migration and invasion of breast cancer cells. Overexpression of GRB7 could abolish this effect. miR‑193a‑3p could directly target the 3' untranslated region of GRB7. miR‑193a‑3p could directly or indirectly target extracellular signal‑regulated kinase 1/2 (ERK1/2) and forkhead box M1 (FOXM1) signaling. In conclusion, it was identified that silencing of miR‑193a‑3p through hypermethylation can promote HER2 positive breast cancer progress by targeting GRB7, ERK1/2 and FOXM1 signaling. The function of miR‑193a‑3p in HER2 positive breast cancer implicates its potential application in therapy.

Targeting forkhead box M1 transcription factor in breast cancer

Breast cancer continues to be the most commonly diagnosed malignancy and second most common cause of cancer-related deaths among women in the United States. Improved understanding of the molecular heterogeneity of breast tumors and the approval of multiple targeted therapies have revolutionized the treatment landscape and long-term survival rates for patients with breast cancer. Despite the development of highly effective targeted agents, drug resistance and disease progression remain major clinical concerns. Improved understanding of the molecular mechanisms mediating drug resistance will allow new treatments to be developed. The forkhead box M1 (FoxM1) transcription factor is overexpressed in breast cancer and strongly associated with resistance to targeted therapies and chemotherapy. FoxM1 regulates all hallmarks of cancer, including proliferation, mitosis, EMT, invasion, and metastasis. Inhibition of FoxM1 transcription factor function is a potential strategy for overcoming breast cancer progression. In this research update, we review the role of FoxM1 in breast cancer and pharmacological approaches for blocking FoxM1 transcription factor function. Future preclinical studies should evaluate combination drug strategies to inhibit FoxM1 function and upstream kinase signaling pathways as potential strategies to treat resistant and metastatic breast cancers.

HER2 and EGFR amplification and expression in urothelial carcinoma occurs in distinct biological and molecular contexts

We analyzed a cohort of 599 cases of urothelial carcinoma for EGFR, ERBB2, and ERBB3 gene expression and genomic alterations. The cohort consisted of a reference set (n = 292) comprising all stages and grades and one set (n = 307) of advanced tumors. All cases were previously classified into urothelial carcinoma molecular subtypes. Genomic amplifications were established by array-CGH or in-situ hybridization, and gene expression both at mRNA and protein levels. Clinical HER2 status was independently evaluated using standard clinical procedures. EGFR amplifications were observed in 14% and ERBB2 amplifications in 23% of the reference cohort. EGFR gains were enriched in the Basal/SCC-like and ERBB2 gains in the Genomically Unstable subtypes. The expression data suggests that the Genomically Unstable show high ERBB2/ERBB3 but low EGFR expression and that Basal/SCC-like tumors show high EGFR but low ERBB2/ERBB3 expression. Whereas the frequency of ERBB2 genomic amplification were similar for cases of the Genomically Unstable subtype in the two cohorts, the Urothelial-like subtype acquires ERBB2 amplifications and expression during progression. Even though a good correlation between gene amplification and ERBB2 gene expression was observed in the Urothelial-like and Genomically Unstable subtypes less than half of the Basal/SCC-like cases with ERBB2 amplification showed concomitant ERBB2 mRNA and protein expression. We conclude that clinical trials using ERBB2 (HER2) or EGFR as targets have not fully appreciated the molecular heterogeneity in which activated ERBB2 and EGFR systems operate. Proper tumor classification is likely to be critical for arriving at thorough conclusions regarding new HER2 and EGFR based treatment regimes.

FoxM1 is an independent poor prognostic marker and therapeutic target for advanced Middle Eastern breast cancer

Breast cancer (BC) is the most common cause of cancer-related death in females in Saudi Arabia. BC in Saudi women tend to behave more aggressively than breast cancer in the West. Therefore, identification of new molecular targets and treatment strategies are highly warranted to improve patient outcome. FoxM1 has been shown to play a critical role in pathogenesis of various malignancies. In this study, we explored the prevalence and clinical implication of FoxM1 overexpression in Saudi breast cancer. FoxM1 protein overexpression was seen in 79% (770/975) of BC tissues and was associated with aggressive clinical parameters such as younger age (< 30 yrs) (p = 0.0172), high grade (p < 0.0001), mucinous histology (p < 0.0001) and triple negative phenotype (p < 0.0001). Overexpression of FoxM1 was significantly associated with activated AKT (p < 0.0001), Ki67 expression (p < 0.0001), VEGF (p < 0.0001), MMP-9 (p < 0.0001), XIAP (p < 0.0001) and Bcl-xL (p = 0.0300). Importantly, FoxM1 overexpression is found to be an independent prognostic marker in multivariate analysis in advanced stage (Stage III and IV) breast cancer (p = 0.0298). In vitro data using BC cell lines showed that down-regulation of FoxM1 using specific inhibitor, thiostrepton or siRNA inhibited cell migration, invasion and angiogenesis. In addition, treatment of BC cell lines with thiostrepton resulted in inhibition of proliferation and induction of apoptosis in a dose-dependent manner. In vivo, thiostrepton treatment regressed MDA-MB-231 cells generated xenografts via down-regulation of FoxM1 and its downstream targets. Our results suggest that FoxM1 may be a potential therapeutic target for the treatment of aggressive breast cancers.

UBE2C Is a Transcriptional Target of the Cell Cycle Regulator FOXM1

FOXM1 (forkhead box protein M1) is a transcription factor that participates in all stages of tumor development, mainly through the control of cell cycle and proliferation, regulating the expression of genes involved in G1/S and G2/M transition and M phase progression. The ubiquitin conjugating enzyme E2 (UBE2C) is a member of the anaphase promoting complex/cyclosome, promoting the degradation of several target proteins along cell cycle progression, during metaphase/anaphase transition. FOXM1 and UBE2C have been found overexpressed in a wide range of different solid tumors. Therefore, the aim of this study was to investigate whether UBE2C is a transcriptional target of FOXM1, using esophageal squamous cell carcinoma (ESCC) as a model, in addition to several cancer-deposited data. Our results show that FOXM1 and UBE2C expression present a positive correlation in normal tissues and in 25 distinct tumor types, including ESCC, where these genes are overexpressed. Moreover, FOXM1 binds to UBE2C promoter region in ESCC cell line and transcriptionally activates it, leading to UBE2C upregulation. In conclusion, this study provides evidences that FOXM1 transcriptionally regulates UBE2C expression in ESCC and their deregulation may be a general phenomenon in human neoplasias.

Transcription factor FoxM1 is the downstream target of c-Myc and contributes to the development of prostate cancer

Background

Prostate cancer is a common malignancy and the second leading cause of cancer death in men. Elevated expression of the transcription factor FoxM1 and c-Myc has been identified in prostate cancer. However, the potential mechanism of elevated FoxM1 and c-Myc to the development of prostate cancer has not been identified.

Methods

In this report, the mRNA level of FoxM1 and c-Myc was detected in 30 prostate cancer and para-cancer tissues. Then, we detected the expression level of FoxM1 by real-time PCR and Western blot after disturbance of the expression level of c-Myc in PC-3 cells. Whether c-Myc could bind to FoxM1 promoter was identified by ChIP assay. Finally, the migratory, invasive, and proliferative abilities in FoxM1 overexpressing and silencing PC-3 cells were detected by wound healing, transwell assay, CCK-8 assays, and Ki-67 protein level.

Results

We found that the expression level of FoxM1 and c-Myc were both increased in prostate cancer samples compared with para-cancer samples. The expression level of FoxM1 was changed consistent with the protein level of c-Myc. ChIP assay detected the direct binding of c-Myc in FoxM1 gene promoter. Lastly, overexpression of FoxM1 increased the migratory, invasive, and proliferative abilities of PC-3 cells, and its downregulation significantly decreased the migratory, invasive, and proliferative abilities.

Conclusions

In conclusion, FoxM1 was significantly increased in prostate cancer samples, and it could regulate the proliferative and invasive ability of prostate cancer cells which might be a new target for prostate cancer. Besides, c-Myc could regulate the expression level of FoxM1 by directly binding to its gene promoter.

FOXM1 confers resistance to gefitinib in lung adenocarcinoma via a MET/AKT-dependent positive feedback loop

Gefitinib resistance remains a major problem in the treatment of lung adenocarcinoma. However, the molecular mechanisms of gefitinib resistance are not fully understood. In this study, we characterized the critical role of transcription factor Forkhead box protein M1 (FOXM1) in gefitinib resistance of lung adenocarcinoma cells. In vitro drug sensitivity assays demonstrated that FOXM1 inhibition sensitized PC9/GR and HCC827/GR cells to gefitinib, whereas FOXM1 overexpression enhanced PC9 and HCC827 cell resistance to gefitinib. Increased FOXM1 resulted in the upregulation of hepatocyte growth factor receptor (MET), which led to activation of the protein kinase B (AKT) pathway, whereas knockdown of FOXM1 did the opposite. FOXM1 bound directly to the MET promoter regions and regulated the promoter activities and the expression of MET at the transcriptional level. Moreover, MET/AKT pathway upregulated the expression of FOXM1 in lung adenocarcinoma cells. Inhibition of pAKT by LY294002 or inhibition of pMET by PHA-665752 significantly inhibited the expression of FOXM1 in lung adenocarcinoma cells. Importantly, we further demonstrated that the expression levels of FOXM1, pAKT and MET were significantly increased in lung adenocarcinoma tissues relative to normal lung tissues, and these three biomarkers were concomitantly overexpressed in lung adenocarcinoma tissues. Taken together, our results indicate that FOXM1 promotes acquired resistance to gefitinib of lung adenocarcinoma cells, and FOXM1 crosstalks with MET/AKT signaling to form a positive feedback loop to promote lung adenocarcinoma development.

FoxM1 is a promising candidate target in the treatment of breast cancer

Forkhead box protein M1(FoxM1) is a member of forkhead superfamily transcription factors. Emerging evidences have progressively contributed to our understanding on a central role of FoxM1 in human cancers. However, perspectives on the function of FoxM1 in breast cancer (BC) remain conflicting, and mostly were from basic research. Here, we explored the expression profile and prognostic values of FoxM1 based on analysis of pooled clinical datasets derived from online accessible databases, including ONCOMINE, Breast Cancer Gene-Expression Miner v4.0, and Kaplan-Meier plotter. It was found that, FoxM1 mRNA expression was significantly higher in breast tumor versus normal control. FoxM1expression profile presented a distinct pattern in different molecular subtypes of BC patients. Higher expression of FoxM1 was correlated to low mRNA expression of estrogen receptor 1 (ESR1), erb-B2 receptor tyrosine kinase 2 (ERBB2), and was inversely associated with the expression of classical luminal regulators forkhead box protein A1 (FoxA1) and GATA binding protein 3 (GATA3). Elevated FoxM1 expression predicted shorter distance metastasis free survival (DMFS) in BC patients, particularly with estrogen receptor (ER) positive and Luminal A, Luminal B subtypes of BC. More interestingly, elevated FoxM1 expression predicted poor survival in breast cancer patients, especially in the ER (+), progesterone receptor (PR) (+) subgroups and BC patients received adjuvant chemotherapy only or treated with tamoxifen only. These results implied that FoxM1 is an essential prognostic factor and promising candidate target in the treatment of breast cancer.

OTUB1-catalyzed deubiquitination of FOXM1 facilitates tumor progression and predicts a poor prognosis in ovarian cancer

Ubiquitination is essential for regulation of cell physiology, protein stability, and signal transduction [1]. Its dysregulation is an important factor in many diseases, including cancer. We explored the potential OTUB1-catalyzed deubiquitination of FOXM1, a transcription factor linked to carcinogenesis, and the biological consequence of that interaction in ovarian cancer. We found that FOXM1 is ubiquitinated by multiple polyUb chains and targeted for proteosomal degradation in a reaction dependent on its ubiquitination-required KEN box. Additionally, the OTUB1 N-terminus and catalytic triad bind to FOXM1, specifically catalyzing cleavage of the K48-specific ubiquitin linkage from FOXM1. Moreover, OTUB1-FOXM1 interaction drives tumor progression and OTUB1 expression predicts a poor prognosis in ovarian cancer. Our study suggests that inhibiting OTUB1-FOXM1 interaction is a potential new avenue for ovarian cancer therapy.

Correlation of HER2 and FOXM1 in human colorectal carcinoma and its clinical significance

BACKGROUND

The human epidermal growth factor receptor 2 (HER2) and transcription factor forkhead box protein M1 (FOXM1) are proto-oncogenes and have expressed in various kinds of human solid malignancies. However, the clinical significance of HER2 and FOXM1 in colorectal cancer (CRC) remains controversial, and there is no related report of the connection between HER2 and FOXM1 in colorectal cancer. This study aims to investigate the clinical values based on the connection of HER2 with FOXM1 in colorectal cancer.

MATERIAL/METHODS

We retrospectively investigated HER2 and FOXM1 expressions of 130 paraffin embedded CRC and their adjacent paraneoplastic tissues through immunohistochemical assay. Western blot and RT-PCR assays were applied to measure the relative expressions of HER2 and FOXM1 in mRNA and the protein levels of 30 fresh CRC and the adjacent paraneoplastic tissues.

RESULTS

HER2 and FOXM1 expressions were significantly higher in colorectal cancer than those in paraneoplastic tissues (P<0.001). Similarly, the relative expression levels of HER2 and FOXM1 in mRNA and protein were also significantly higher in CRC tissues than those in paraneoplastic tissues (P<0.05). The HER2 expression was closely correlated with tumor size, degree of differentiation, presence of vascular invasion, lymph node metastasis, distant metastases, advanced TNM stage, and prognosis (P<0.05). The FOXM1 expression was related to tumor invasion, vascular invasion, lymph node metastasis, distant metastases, TNM stage, and prognosis (P<0.05). Besides, FOXM1 was an independent prognostic factor in CRC. There was a significant correlation between FOXM1 and HER2 expressions in colorectal cancer (r=0.335; P<0.01).

CONCLUSIONS

The overexpressions of HER2 and FOXM1 protein in colorectal cancer correlate with their clinicopathological characteristics and prognosis. HER2 and FOXM1 are important diagnostic markers for colorectal cancer. Furthermore, FOXM1 may be a potential target for therapy especially in HER2-targeted therapy-resistant cancers.

FOXM1 regulates expression of eukaryotic elongation factor 2 kinase and promotes proliferation, invasion and tumorgenesis of human triple negative breast cancer cells

Eukaryotic elongation factor 2 kinase (eEF2K), an emerging molecular target for cancer therapy, contributes to cancer proliferation, cell survival, tumorigenesis, and invasion, disease progression and drug resistance. Although eEF2K is highly up-regulated in various cancers, the mechanism of gene regulation has not been elucidated. In this study, we examined the role of Forkhead Box M1 (FOXM1) proto-oncogenic transcription factor in triple negative breast cancer (TNBC) cells and the regulation of eEF2K. We found that FOXM1 is highly upregulated in TNBC and its knockdown by RNA interference (siRNA) significantly inhibited eEF2K expression and suppressed cell proliferation, colony formation, migration, invasion and induced apoptotic cell death, recapitulating the effects of eEF2K inhibition. Knockdown of FOXM1 inhibited regulators of cell cycle, migration/invasion and survival, including cyclin D1, Src and MAPK-ERK signaling pathways, respectively. We also demonstrated that FOXM1 (1B and 1C isoforms) directly binds to and transcriptionally regulates eEF2K gene expression by chromatin immunoprecipitation (ChIP) and luciferase gene reporter assays. Furthermore, in vivo inhibition of FOXM1 by liposomal siRNA-nanoparticles suppressed growth of MDA-MB-231 TNBC tumor xenografts in orthotopic models. In conclusion, our study provides the first evidence about the transcriptional regulation of eEF2K in TNBC and the role of FOXM1 in mediating breast cancer cell proliferation, survival, migration/invasion, progression and tumorgenesis and highlighting the potential of FOXM1/eEF2K axis as a molecular target in breast and other cancers.

The FOXO3-FOXM1 axis: A key cancer drug target and a modulator of cancer drug resistance

The FOXO3 and FOXM1 forkhead box transcription factors, functioning downstream of the essential PI3K-Akt, Ras-ERK and JNK/p38MAPK signalling cascades, are crucial for cell proliferation, differentiation, cell survival, senescence, DNA damage repair and cell cycle control. The development of resistance to both conventional and newly emerged molecularly targeted therapies is a major challenge confronting current cancer treatment in the clinic. Intriguingly, the mechanisms of resistance to ‘classical’ cytotoxic chemotherapeutics and to molecularly targeted therapies are invariably linked to deregulated signalling through the FOXO3 and FOXM1 transcription factors. This is owing to the involvement of FOXO3 and FOXM1 in the regulation of genes linked to crucial drug action-related cellular processes, including stem cell renewal, DNA repair, cell survival, drug efflux, and deregulated mitosis. A better understanding of the mechanisms regulating the FOXO3-FOXM1 axis, as well as their downstream transcriptional targets and functions, may render these proteins reliable and early diagnostic/prognostic factors as well as crucial therapeutic targets for cancer treatment and importantly, for overcoming chemotherapeutic drug resistance.

Prognostic genes of breast cancer revealed by gene co-expression network analysis

The aim of the present study was to identify genes that may serve as markers for breast cancer prognosis by constructing a gene co-expression network and mining modules associated with survival. Two gene expression datasets of breast cancer were downloaded from ArrayExpress and genes from these datasets with a coefficient of variation >0.5 were selected and underwent functional enrichment analysis with the Database for Annotation, Visualization and Integration Discovery. Gene co-expression networks were constructed with the WGCNA package in R. Modules were identified from the network via cluster analysis. Cox regression was conducted to analyze survival rates. A total of 2,669 genes were selected, and functional enrichment analysis of them revealed that they were mainly associated with the immune response, cell proliferation, cell differentiation and cell adhesion. Seven modules were identified from the gene co-expression network, one of which was found to be significantly associated with patient survival time. Expression status of 144 genes from this module was used to cluster patient samples into two groups, with a significant difference in survival time revealed between these groups. These genes were involved in the cell cycle and tumor protein p53 signaling pathway. The top 10 hub genes were identified in the module. The findings of the present study could advance the understanding of the molecular pathogenesis of breast cancer.

Oxidative Stress Gene Expression Profile Correlates with Cancer Patient Poor Prognosis: Identification of Crucial Pathways Might Select Novel Therapeutic Approaches

The role of altered redox status and high reactive oxygen species (ROS) is still controversial in cancer development and progression. Intracellular levels of ROS are elevated in cancer cells suggesting a role in cancer initiation and progression; on the contrary, ROS elevated levels may induce programmed cell death and have been associated with cancer suppression. Thus, it is crucial to consider the double-face of ROS, for novel therapeutic strategies targeting redox regulatory mechanisms. In this review, in order to derive cancer-type specific oxidative stress genes' profile and their potential prognostic role, we integrated a publicly available oxidative stress gene signature with patient survival data from the Cancer Genome Atlas database. Overall, we found several genes statistically significant associated with poor prognosis in the examined six tumor types. Among them, FoxM1 and thioredoxin reductase1 expression showed the same pattern in four out of six cancers, suggesting their specific critical role in cancer-related oxidative stress adaptation. Our analysis also unveiled an enriched cellular network, highlighting specific pathways, in which many genes are strictly correlated. Finally, we discussed novel findings on the correlation between oxidative stress and cancer stem cells in order to define those pathways to be prioritized in drug development.

Dacomitinib, a pan-inhibitor of ErbB receptors, suppresses growth and invasive capacity of chemoresistant ovarian carcinoma cells

Epithelial ovarian cancer (EOC) is the most lethal gynaecological malignancy worldwide. Development of chemoresistance and peritoneal dissemination of EOC cells are the major reasons for low survival rate. Targeting signal transduction pathways which promote therapy resistance and metastatic dissemination is the key to successful treatment. Members of the ErbB family of receptors are over-expressed in EOC and play key roles in chemoresistance and invasiveness. Despite this, single-targeted ErbB inhibitors have demonstrated limited activity in chemoresistant EOC. In this report, we show that dacomitinib, a pan-ErbB receptor inhibitor, diminished growth, clonogenic potential, anoikis resistance and induced apoptotic cell death in therapy-resistant EOC cells. Dacominitib inhibited PLK1-FOXM1 signalling pathway and its down-stream targets Aurora kinase B and survivin. Moreover, dacomitinib attenuated migration and invasion of the EOC cells and reduced expression of epithelial-to-mesenchymal transition (EMT) markers ZEB1, ZEB2 and CDH2 (which encodes N-cadherin). Conversely, the anti-tumour activity of single-targeted ErbB agents including cetuximab (a ligand-blocking anti-EGFR mAb), transtuzumab (anti-HER2 mAb), H3.105.5 (anti-HER3 mAb) and erlotinib (EGFR small-molecule tyrosine kinase inhibitor) were marginal. Our results provide a rationale for further investigation on the therapeutic potential of dacomitinib in treatment of the chemoresistant EOC.

Plk1 Regulates the Repressor Function of FoxM1b by inhibiting its Interaction with the Retinoblastoma Protein

FoxM1b is a cell cycle-regulated transcription factor, whose over-expression is a marker for poor outcome in cancers. Its transcriptional activation function requires phosphorylation by Cdk1 or Cdk2 that primes FoxM1b for phosphorylation by Plk1, which triggers association with the co-activator CBP. FoxM1b also possesses transcriptional repression function. It represses the mammary differentiation gene GATA3 involving DNMT3b and Rb. We investigated what determines the two distinct functions of FoxM1b: activation and repression. We show that Rb binds to the C-terminal activation domain of FoxM1b. Analyses with phospho-defective and phospho-mimetic mutants of FoxM1b identified a critical role of the Plk1 phosphorylation sites in regulating the binding of FoxM1b to Rb and DNMT3b. That is opposite of what was seen for the interaction of FoxM1b with CBP. We show that, in addition to GATA3, FoxM1b also represses the mammary luminal differentiation marker FoxA1 by promoter-methylation, and that is regulated by the Plk1 phosphorylation sites in FoxM1b. Our results show that the Plk1 phosphorylation sites in FoxM1b serve as a regulator for its repressor function, and they provide insights into how FoxM1b inhibits differentiation genes and activates proliferation genes during cancer progression.

Roles of FoxM1 in cell regulation and breast cancer targeting therapy

Forkhead box M1 (FoxM1) is an oncogenic transcription factor involved in a wide variety of cellular processes, such as cell cycle progression, proliferation, differentiation, migration, metabolism and DNA damage response. It is overexpressed in many human cancers, especially in breast cancers. Posttranslational modifications are known to play an important role in regulating the expression and transcriptional activity of FoxM1. In this review, we characterize the posttranslational modifications of FoxM1, summarize modifications of FoxM1 by different kinases, explore the relationship between the different sites of modifications and comprehensively describe how posttranslational modifications to regulate the function of FoxM1 by changing protein stability, nucleus localization and transcriptional activity. Additionally, we systematically summarize the roles of FoxM1 in breast cancer occurrence, therapy and drug resistance. The purpose of this paper tries to give a better understanding of the regulatory mechanisms of FoxM1 in cell regulation and highlights potential of a new method for breast cancer therapy by targeting FoxM1.

Expression of FOXM1 and related proteins in breast cancer molecular subtypes

Forkhead box (FOX) proteins constitute an extended family of transcriptional regulators. FOXM1 is ubiquitously expressed in cells undergoing proliferation, and overexpression of FOXM1 is associated with poor prognosis in various malignant tumours. FOXM1 and FOXO3a are often transcriptionally antagonistic. FOXO3a plays a critical tumour-suppressive role in breast cancer. FOXO activity is modulated by its acetylation status, which is regulated by class III histone deacetylases (sirtuins; also known as SIRTs). This study evaluated the role of FOX proteins and their regulators in each molecular subtype of breast cancer. Immunohistochemical expressions of FOXM1, FOXO3a, SIRT1 and SIRT6 were evaluated in tissue microarray blocks containing 688 consecutive breast cancer samples. Mean expression levels were used to categorize tumours according to the expression of each protein (high or low). High expression of FOXM1 was significantly correlated with high SIRT1 and SIRT6 expression, higher histologic grade and triple-negative breast cancer (TNBC). High expression of nuclear FOXO3a and nuclear SIRT1 was correlated with a lower histologic grade and the hormone receptor-positive/HER2-negative subtype. In survival analysis, FOXM1 was an independent adverse prognostic factor for disease-free and overall survival in the hormone receptor-positive/HER2-negative subtype but not in the HER2-positive subtype or TNBC. In conclusion, although high FOXM1 expression was noted in the TNBC subtype, it had no prognostic impact in TNBC. However, it had prognostic significance in the hormone receptor-positive/HER2-negative subtype.

Effect of taxol on the expression of FoxM1 ovarian cancer-associated gene

The incidence of ovarian cancer in women has been on the increase in recent years. The aim of the present study was to examine the effects of taxol on the expression of ovarian cancer-associated gene forkhead box transcription factor M1 (FoxM1) and its therapeutic effects for ovarian cancer. The expression of FoxM1 gene was examined in patients with or without ovarian cancer. RNA and protein levels of FoxM1 gene of ovarian cancer patients were detected at different time periods (1, 3, 6, 8, 12 and 24 months) after treatment with taxol. The results showed that the mRNA level of FoxM1 gene in patients with ovarian cancer was significantly higher than that in normal women (P<0.05). With time and progression of the disease, the expression of FoxM1 gene significantly increased in the patients not being administered taxol, whereas the expression of FoxM1 in the patients administered taxol was significantly lower comparatively (P<0.05). In conclusion, an asssociation was identified between the FoxM1 gene and ovarian cancer. The FoxM1 gene therefore promotes the generation and deterioration of ovarian cancer, whereas taxol reduces it. These findings provide a certain theoretical basis for the later treatment of ovarian cancer disease.

FoxM1 promotes breast tumorigenesis by activating PDGF-A and forming a positive feedback loop with the PDGF/AKT signaling pathway

The autocrine platelet-derived growth factor (PDGF)/PDGF receptor (PDGFR) signaling pathway promotes breast cancer tumorigenesis, but the mechanisms for its dysregulation in breast cancer are largely unknown. In the study, we identified PDGF-A as a novel transcriptional target of FoxM1. FoxM1 directly binds to two sites in the promoter of PDGF-A and activates its transcription. Mutation of these FoxM1-binding sites diminished PDGF-A promoter activity. Increased FoxM1 resulted in the upregulation of PDGF-A, which led to activation of the AKT pathway and increased breast cancer cell proliferation and tumorigenesis, whereas knockdown of FoxM1 does the opposite. Blocking AKT activation with a phosphoinositide 3-kinase/AKT inhibitor decreased FoxM1-induced cell proliferation. Moreover, PDGF/AKT pathway upregulates the expression of FoxM1 in breast cancer cells. Knockdown of PDGF-A or blockade of AKT activation inhibited the expression of FoxM1 in breast cancer cells. Furthermore, expression of FoxM1 significantly correlated with the expression of PDGF-A and the activated AKT signaling pathway in human breast cancer specimens. Our study demonstrates a novel positive regulatory feedback loop between FoxM1 and the PDGF/AKT signaling pathway; this loop contributes to breast cancer cell growth and tumorigenesis.

Paclitaxel targets FOXM1 to regulate KIF20A in mitotic catastrophe and breast cancer paclitaxel resistance

FOXM1 has been implicated in taxane resistance, but the molecular mechanism involved remains elusive. In here, we show that FOXM1 depletion can sensitize breast cancer cells and mouse embryonic fibroblasts into entering paclitaxel-induced senescence, with the loss of clonogenic ability, and the induction of senescence-associated β-galactosidase activity and flat cell morphology. We also demonstrate that FOXM1 regulates the expression of the microtubulin-associated kinesin KIF20A at the transcriptional level directly through a Forkhead response element (FHRE) in its promoter. Similar to FOXM1, KIF20A expression is downregulated by paclitaxel in the sensitive MCF-7 breast cancer cells and deregulated in the paclitaxel-resistant MCF-7Tax(R) cells. KIF20A depletion also renders MCF-7 and MCF-7Tax(R) cells more sensitive to paclitaxel-induced cellular senescence. Crucially, resembling paclitaxel treatment, silencing of FOXM1 and KIF20A similarly promotes abnormal mitotic spindle morphology and chromosome alignment, which have been shown to induce mitotic catastrophe-dependent senescence. The physiological relevance of the regulation of KIF20A by FOXM1 is further highlighted by the strong and significant correlations between FOXM1 and KIF20A expression in breast cancer patient samples. Statistical analysis reveals that both FOXM1 and KIF20A protein and mRNA expression significantly associates with poor survival, consistent with a role of FOXM1 and KIF20A in paclitaxel action and resistance. Collectively, our findings suggest that paclitaxel targets the FOXM1-KIF20A axis to drive abnormal mitotic spindle formation and mitotic catastrophe and that deregulated FOXM1 and KIF20A expression may confer paclitaxel resistance. These findings provide insights into the underlying mechanisms of paclitaxel resistance and have implications for the development of predictive biomarkers and novel chemotherapeutic strategies for paclitaxel resistance.

The Role of Forkhead Box Protein M1 in Breast Cancer Progression and Resistance to Therapy

The Forkhead box M1 (FOXM1) is a transcription factor that has been implicated in normal cell growth and proliferation through control of cell cycle transition and mitotic spindle. It is implicated in carcinogenesis of various malignancies where it is activated by either amplification, increased stability, enhanced transcription, dysfunction of regulatory pathways, or activation of PI3K/AKT, epidermal growth factor receptor, Raf/MEK/MAPK, and Hedgehog pathways. This review describes the role of FOXM1 in breast cancer. This includes how FOXM1 impacts on different subtypes of breast cancer, that is, luminal/estrogen receptor positive (ER+), expressing human epidermal growth factor receptor 2 (HER2), basal-like breast cancer (BBC), and triple negative breast cancer (TNBC). The review also describes different tested preclinical therapeutic strategies targeting FOXM1. Developing clinically applicable therapies that specifically inhibit FOXM1 activity is a logical next step in biomarker-driven approaches against breast cancer but will not be without its challenges due to the unique properties of this transcription factor.

Expression of Forkhead box M1 in soft tissue leiomyosarcoma: Clinicopathologic and in vitro study using a newly established cell line

Leiomyosarcoma (LMS) of soft tissue is a sarcoma with smooth‐muscle differentiation, and conventional chemotherapy does not improve its outcome. The application of novel antitumor agents and precise prognostication has been demanded. The expression of the protein Forkhead box M1 (FOXM1), a member of the FOX family, is considered an independent predictor of poor survival in many cancers and sarcomas. However, the expression status of FOXM1 in LMS is poorly understood. The purposes of this study were to examine the correlation between the expression of FOXM1 and clinicopathologic or prognostic factors and to clarify the efficacy of FOXM1 target therapy in LMS. We evaluated the immunohistochemical expressions of FOXM1 using 123 LMS tumor specimens. Univariate and multivariate survival analyses revealed that FOXM1 expression was associated with poor prognosis in LMS. An in vitro study was then carried out to examine the antitumor effect of a FOXM1 inhibitor (thiostrepton) and siRNA on a novel LMS cell line, TC616. We also assessed the efficacy of the combined use of doxorubicin and thiostrepton. Thiostrepton showed dose‐dependent antitumor activity and TC616 cells treated with the combination of thiostrepton and doxorubicin showed lower proliferation compared to those treated with either drug individually. FOXM1 interruption by siRNA decreased cell proliferation and increased chemosensitivity. In conclusion, FOXM1 has potential to be a therapeutic target for LMS.

Targeting of mutant p53-induced FoxM1 with thiostrepton induces cytotoxicity and enhances carboplatin sensitivity in cancer cells

FoxM1 is an oncogenic Forkhead transcription factor that is overexpressed in ovarian cancer. However, the mechanisms by which FoxM1 is deregulated in ovarian cancer and the extent to which FoxM1 can be targeted in ovarian cancer have not been reported previously. In this study, we showed that MDM2 inhibitor Nutlin-3 upregulated p53 protein and downregulated FoxM1 expression in several cancer cell lines with wild type TP53 but not in cell lines with mutant TP53. FoxM1 downregulation was partially blocked by cycloheximide or actinomycin D, and pulse-chase studies indicate Nutlin-3 enhances FoxM1 mRNA decay. Knockdown of p53 using shRNAs abrogated the FoxM1 downregulation by Nutlin-3, indicating a p53-dependent mechanism. FoxM1 inhibitor, thiostrepton, induces apoptosis in cancer cell lines and enhances sensitivity to cisplatin in these cells. Thiostrepton downregulates FoxM1 expression in several cancer cell lines and enhances sensitivity to carboplatin in vivo. Finally, FoxM1 expression is elevated in nearly all (48/49) ovarian tumors, indicating that thiostrepton target gene is highly expressed in ovarian cancer. In summary, the present study provides novel evidence that both amorphic and neomorphic mutations in TP53 contribute to FoxM1 overexpression and that FoxM1 may be targeted for therapeutic benefits in cancers.

OGFOD1 is required for breast cancer cell proliferation and is associated with poor prognosis in breast cancer

2-oxogluatrate and Fe(II)-dependent oxygenase domain-containing protein 1 (OGFOD1) was recently revealed to be a proline hydroxylase of RPS23 for translational termination. However, OGFOD1 is nuclear, whereas translational termination occurs in the cytoplasm, raising the possibility of another function of OGFOD1 in the nucleus. In this study, we demonstrate that OGFOD1 is involved in cell cycle regulation. OGFOD1 knockdown in MDA-MB-231 breast cancer cells significantly impeded cell proliferation and resulted in the accumulation of G1 and G2/M cells by decreasing the mRNA levels of G1/S transition- and G2/M-related transcription factors and their target genes. We also confirmed that OGFOD1 is highly expressed in breast cancer tissues by bioinformatic analysis and immunohistochemistry. Thus, we propose that OGFOD1 is required for breast cancer cell proliferation and is associated with poor prognosis in breast cancer.

Hyperplastic Growth of Pulmonary Artery Smooth Muscle Cells from Subjects with Pulmonary Arterial Hypertension Is Activated through JNK and p38 MAPK

Smooth muscle in the pulmonary artery of PAH subjects, both idiopathic and hereditary, is characterized by hyperplasia. Smooth muscle cells (HPASMC) isolated from subjects with or without PAH retain their in vivo phenotype as illustrated by their expression of alpha-smooth muscle actin and expression of H-caldesmon. Both non PAH and PAH HPASMC display a lengthy, approximately 94h, cell cycle. The HPASMC from both idiopathic and hereditary PAH display an abnormal proliferation characterized by continued growth under non-proliferative, non-growth stimulated conditions. This effector independent proliferation is JNK and p38 MAP kinase dependent. Blocking the activation of either abrogates the HPASMC growth. HPASMC from non PAH donors under quiescent conditions display negligible proliferation but divide upon exposure to growth factors such as PDGF-BB or FGF2 but not EGF. This growth does not involve the MAP kinases. Instead it routes via the tyrosine kinase receptor through mTOR and then 6SK. In the PAH cells PDGF-BB and FGF2 augment the dysregulated cell proliferation, also through mTOR/6SK. Additionally, blocking the activation of mTOR also modulates the MAP kinase promoted dysregulated growth. These results highlight key alterations in the growth of HPASMC from subjects with PAH which contribute to the etiology of the disease and can clearly be targeted at various regulatory points for future therapies.

Increased expression of forkhead box M1 is associated with aggressive phenotype and poor prognosis in estrogen receptor-positive breast cancer

Fox transcription factors play a critical role in the regulation of a variety of biological processes. While FoxM1 behaves like the oncogenic transcription factor, FoxO3a is known as a tumor suppressor by inhibiting FoxM1. This study aimed to investigate the clinicopathological significance of FoxM1 and FoxO3a expression in breast cancer. Expression of FoxM1 and FoxO3a were analyzed by immunohistochemical staining on tissue microarray sections from 236 breast cancer patients, and correlated with various clinicopathological characteristics. Overexpression of FoxM1 correlated with adverse clinicopathological features, such as larger tumor size, lymph node metastasis, advanced tumor stage, and lymphovascular invasion. The Kaplan-Meier survival curves revealed no prognostic significance of FoxM1 expression. However, in subgroup analyses with patients of estrogen receptor (ER) positive breast cancers, FoxM1 overexpression associated with poor disease free and overall survival. No association was found between FoxO3a and FoxM1 expression. Regarding clinicopathological variables, the only association between histologic grade and FoxO3a was observed. In conclusion, FoxM1 overexpression was significantly associated with aggressive phenotypes and poor prognosis of ER-positive breast cancer. These findings suggest the possible role of FoxM1 as a prognostic biomarker and putative target of anti-cancer therapy.

Overexpression of forkhead box protein M1 (FOXM1) in ovarian cancer correlates with poor patient survival and contributes to paclitaxel resistance

Aim

Deregulation of FOXM1 has been documented in various cancers. The aim of this study was to evaluate the role of FOXM1 in ovarian cancer tumorigenesis and paclitaxel resistance.

Experimental Design

Expression of FOXM1 was examined in 119 clinical samples by immunohistochemistry and correlated with clinicopathological parameters. Effects of FOXM1 knockdown on ovarian cancer cell migration, invasion and mitotic catastrophe were also studied. qPCR and ChIP-qPCR were used to establish KIF2C as a novel FOXM1 target gene implicated in chemoresistance.

Results

High nuclear FOXM1 expression in ovarian cancer patient samples was significantly associated with advanced stages (P = 0.035), shorter overall (P = 0.019) and disease-free (P = 0.014) survival. Multivariate analysis confirmed FOXM1 expression as an independent prognostic factor for ovarian cancer. FOXM1 knockdown significantly inhibited migration and invasion of ovarian cancer cells and enhanced paclitaxel-mediated cell death and mitotic catastrophe in a p53-independent manner. Bioinformatics analysis suggested a number of potential transcription targets of FOXM1. One of the potential targets, KIF2C, exhibited similar expression pattern to FOXM1 in chemosensitive and chemoresistant cells in response to paclitaxel treatment. FOXM1 could be detected at the promoter of KIF2C and FOXM1 silencing significantly down-regulated KIF2C.

Conclusion

Our findings suggest that FOXM1 is associated with poor patient outcome and contributes to paclitaxel resistance by blocking mitotic catastrophe. KIF2C is identified as a novel FOXM1 transcriptional target that may be implicated in the acquisition of chemoresistance. FOXM1 should be further investigated as a potential prognostic marker and therapeutic target for ovarian cancer.

Insulin-like growth factor-1 receptor signaling increases the invasive potential of human epidermal growth factor receptor 2-overexpressing breast cancer cells via Src-focal adhesion kinase and forkhead box protein M1

Resistance to the human epidermal growth factor receptor (HER2)-targeted antibody trastuzumab is a major clinical concern in the treatment of HER2-positive metastatic breast cancer. Increased expression or signaling from the insulin-like growth factor-1 receptor (IGF-1R) has been reported to be associated with trastuzumab resistance. However, the specific molecular and biologic mechanisms through which IGF-1R promotes resistance or disease progression remain poorly defined. In this study, we found that the major biologic effect promoted by IGF-1R was invasion, which was mediated by both Src-focal adhesion kinase (FAK) signaling and Forkhead box protein M1 (FoxM1). Cotargeting IGF-1R and HER2 using either IGF-1R antibodies or IGF-1R short hairpin RNA in combination with trastuzumab resulted in significant but modest growth inhibition. Reduced invasion was the most significant biologic effect achieved by cotargeting IGF-1R and HER2 in trastuzumab-resistant cells. Constitutively active Src blocked the anti-invasive effect of IGF-1R/HER2 cotargeted therapy. Furthermore, knockdown of FoxM1 blocked IGF-1-mediated invasion, and dual targeting of IGF-1R and HER2 reduced expression of FoxM1. Re-expression of FoxM1 restored the invasive potential of IGF-1R knockdown cells treated with trastuzumab. Overall, our results strongly indicate that therapeutic combinations that cotarget IGF-1R and HER2 may reduce the invasive potential of cancer cells that are resistant to trastuzumab through mechanisms that depend in part on Src and FoxM1.

Resistance to HER2-targeted therapies: a potential role for FOXM1

Despite the tremendous efficacy of trastuzumab against HER2-overexpressing metastatic breast cancers, a significant fraction of women demonstrate progressive disease during treatment. Multiple mechanisms have been proposed to mediate trastuzumab resistance. In this mini-review, we discuss the evidence supporting FOXM1 as a mediator of resistance and potential new therapeutic target in trastuzumab-refractory breast cancer. FOXM1 expression is significantly elevated in multiple breast cancer data sets. Some studies suggest a direct correlation between FOXM1 and HER2 expression levels. In addition, overexpression of FOXM1 reduces the sensitivity of HER2-positive breast cancer cells to trastuzumab or lapatinib. Conversely, knockdown or pharmacological inhibition of FOXM1 rescues resistance to HER2-targeted therapies. Current pre-clinical information supports further investigation of the role of FOXM1 in trastuzumab-resistant breast cancer.

Synuclein gamma protects HER2 and renders resistance to Hsp90 disruption

Hsp90 is an important driver of stabilization and activation of several oncogenic proteins in many key pathways in oncogenesis, including HER2. The present study demonstrated that synuclein gamma (SNCG) prevents the protein degradation and protects the function of HER2 in the condition when the function of Hsp90 is blocked. Disruption of Hsp90 resulted in a significant degradation of HER2 and the loss of activity. However, SNCG completely recovered Hsp90 disruption-mediated losses of HER2 and the function. SNCG bound to HER2 in the presence and absence of Hsp90. Specifically, the C-terminal (Gln106-Asp127) of SNCG bound to the loop connecting αC helix and β4 sheet of the kinase domain of HER2. SNCG renders resistance to 17-AAG-induced tumor suppression in tumor xenograft. Crossing SNCG transgenic mice with HER2 mice stimulated HER2-induced tumor growth and rendered resistance to Hsp90 disruption. The present study indicates that SNCG protects Hsp90 client protein of HER2, and renders resistance to Hsp90 disruption.

Next-generation transcriptome sequencing of the premenopausal breast epithelium using specimens from a normal human breast tissue bank

Introduction

Our efforts to prevent and treat breast cancer are significantly impeded by a lack of knowledge of the biology and developmental genetics of the normal mammary gland. In order to provide the specimens that will facilitate such an understanding, The Susan G. Komen for the Cure Tissue Bank at the IU Simon Cancer Center (KTB) was established. The KTB is, to our knowledge, the only biorepository in the world prospectively established to collect normal, healthy breast tissue from volunteer donors. As a first initiative toward a molecular understanding of the biology and developmental genetics of the normal mammary gland, the effect of the menstrual cycle and hormonal contraceptives on DNA expression in the normal breast epithelium was examined.

Methods

Using normal breast tissue from 20 premenopausal donors to KTB, the changes in the mRNA of the normal breast epithelium as a function of phase of the menstrual cycle and hormonal contraception were assayed using next-generation whole transcriptome sequencing (RNA-Seq).

Results

In total, 255 genes representing 1.4% of all genes were deemed to have statistically significant differential expression between the two phases of the menstrual cycle. The overwhelming majority (221; 87%) of the genes have higher expression during the luteal phase. These data provide important insights into the processes occurring during each phase of the menstrual cycle. There was only a single gene significantly differentially expressed when comparing the epithelium of women using hormonal contraception to those in the luteal phase.

Conclusions

We have taken advantage of a unique research resource, the KTB, to complete the first-ever next-generation transcriptome sequencing of the epithelial compartment of 20 normal human breast specimens. This work has produced a comprehensive catalog of the differences in the expression of protein-coding genes as a function of the phase of the menstrual cycle. These data constitute the beginning of a reference data set of the normal mammary gland, which can be consulted for comparison with data developed from malignant specimens, or to mine the effects of the hormonal flux that occurs during the menstrual cycle.

MEK inhibition increases lapatinib sensitivity via modulation of FOXM1

The standard targeted therapy for HER2-overexpressing breast cancer is the HER2 monoclonal antibody, trastuzumab. Although effective, many patients eventually develop trastuzumab resistance. The dual EGFR/HER2 small molecule tyrosine kinase inhibitor lapatinib is approved for use in trastuzumab-refractory metastatic HER2-positive breast cancer. However, lapatinib resistance is a problem as most patients with trastuzumab-refractory disease do not benefit from lapatinib. Understanding the mechanisms underlying lapatinib resistance may ultimately facilitate development of new therapeutic strategies for HER2-overexpressing breast cancer. Our current results indicate that MEK inhibition increases lapatinib-mediated cytotoxicity in resistant HER2-overexpressing breast cancer cells. We genetically and pharmacologically blocked MEK/ERK signaling and evaluated lapatinib response by trypan blue exclusion, anchorage-independent growth assays, flow cytometric cell cycle and apoptosis analysis, and in tumor xenografts. Combined MEK inhibition and lapatinib treatment reduced phosphorylated ERK more than single agent treatment. In addition, Western blots, immunofluorescence, and immunohistochemistry demonstrated that the combination of MEK inhibitor plus lapatinib reduced nuclear expression of the MEK/ERK downstream proto-oncogene FOXM1. Genetic knockdown of MEK was tested for the ability to increase lapatinib-mediated cell cycle arrest or apoptosis in JIMT-1 and MDA361 cells. Finally, xenograft studies demonstrated that combined pharmacological inhibition of MEK plus lapatinib suppressed tumor growth and reduced expression of FOXM1 in HER2-overexpressing breast cancers that are resistant to trastuzumab and lapatinib. Our results suggest that FoxM1 contributes to lapatinib resistance downstream of MEK signaling, and supports further study of pharmacological MEK inhibition to improve response to lapatinib in HER2-overexpressing trastuzumab-resistant breast cancer.