Separase Inhibitor Sepin-1 Inhibits Foxm1 Expression and Breast Cancer Cell Growth

Genome-wide CRISPR screen identifies ESPL1 limits the response of gastric cancer cells to apatinib

Apatinib was the first anti-angiogenic agent approved for treatment of metastatic gastric cancer (GC). However, the emergence of resistance was inevitable. Thus investigating new and valuable off-target effect of apatinib directly against cancer cells is of great significance. Here, we identified extra spindle pole bodies-like 1 (ESPL1) was responsible for apatinib resistance in GC cells through CRISPR genome-wide gain-of-function screening. Loss of function studies further showed that ESPL1 inhibition suppressed cell proliferation, migration and promoted apoptosis in vitro, and accordingly ESPL1 knockdown sensitized GC cells to apatinib. In addition, we found ESPL1 interacted with mouse double minute 2 (MDM2), a E3 ubiquitin protein ligase, and the combination of MDM2 siRNA with apatinib synergistically ameliorated the resistance induced by ESPL1 overexpression. In summary, our study indicated that ESPL1 played a critical role in apatinib resistance in GC cells. Inhibition of MDM2 could rescue the sensitivity of GC cells to apatinib and reverse ESPL1-mediated resistance.

Separase and Roads to Disengage Sister Chromatids during Anaphase

Receiving complete and undamaged genetic information is vital for the survival of daughter cells after chromosome segregation. The most critical steps in this process are accurate DNA replication during S phase and a faithful chromosome segregation during anaphase. Any errors in DNA replication or chromosome segregation have dire consequences, since cells arising after division might have either changed or incomplete genetic information. Accurate chromosome segregation during anaphase requires a protein complex called cohesin, which holds together sister chromatids. This complex unifies sister chromatids from their synthesis during S phase, until separation in anaphase. Upon entry into mitosis, the spindle apparatus is assembled, which eventually engages kinetochores of all chromosomes. Additionally, when kinetochores of sister chromatids assume amphitelic attachment to the spindle microtubules, cells are finally ready for the separation of sister chromatids. This is achieved by the enzymatic cleavage of cohesin subunits Scc1 or Rec8 by an enzyme called Separase. After cohesin cleavage, sister chromatids remain attached to the spindle apparatus and their poleward movement on the spindle is initiated. The removal of cohesion between sister chromatids is an irreversible step and therefore it must be synchronized with assembly of the spindle apparatus, since precocious separation of sister chromatids might lead into aneuploidy and tumorigenesis. In this review, we focus on recent discoveries concerning the regulation of Separase activity during the cell cycle.

siRNA and targeted delivery systems in breast cancer therapy

Recently, nucleic acid drugs have been considered as promising candidates in treatment of various diseases, especially cancer. Because of developing resistance to conventional chemotherapy, use of genetic tools in cancer therapy appears inevitable. siRNA is a RNAi tool with capacity of suppressing target gene. Owing to overexpression of oncogenic factors in cancer, siRNA can be used for suppressing those pathways. This review emphasizes the function of siRNA in treatment of breast tumor. The anti-apoptotic-related genes including Bcl-2, Bcl-xL and survivin can be down-regulated by siRNA in triggering cell death in breast cancer. STAT3, STAT8, Notch1, E2F3 and NF-κB are among the factors with overexpression in breast cancer that their silencing by siRNA paves the way for impairing tumor proliferation and invasion. The oncogenic mechanisms in drug resistance development in breast tumor such as lncRNAs can be suppressed by siRNA. Furthermore, siRNA reducing P-gp activity can increase drug internalization in tumor cells. Because of siRNA degradation at bloodstream and low accumulation at tumor site, nanoplatforms have been employed for siRNA delivery to suppress breast tumor progression via improving siRNA efficacy in gene silencing. Development of biocompatible and efficient nanostructures for siRNA delivery can make milestone progress in alleviation of breast cancer patients.

DRP1 contributes to head and neck cancer progression and induces glycolysis through modulated FOXM1/MMP12 axis

Abnormal DRP1 expression has been identified in a variety of human cancers. However, the prognostic potential and mechanistic role of DRP1 in head and neck cancer (HNC) are currently poorly understood. Here, we demonstrated a significant upregulation of DRP1 in HNC tissues, and that DRP1 expression correlates with poor survival of HNC patients. Diminished DRP1 expression suppressed tumor growth and metastasis in both in vitro and in vivo models. DRP1 expression was positively correlated with FOXM1 and MMP12 expression in HNC patient samples, suggesting pathological relevance in the context of HNC development. Moreover, DRP1 depletion affected aerobic glycolysis through the downregulation of glycolytic genes, and overexpression of MMP12 in DRP1‐depleted cells could help restore glucose consumption and lactate production. Using ChIP‐qPCR, we showed that DRP1 modulates FOXM1 expression, which can enhance MMP12 transcription by binding to its promoter. We also showed that miR‐575 could target 3’UTR of DRP1 mRNA and suppress DRP1 expression. Collectively, our study provides mechanistic insights into the role of DRP1 in HNC and highlights the potential of targeting the miR‐575/DRP1/FOXM1/MMP12 axis as a novel therapy for the prevention of HNC progression.

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.

Functional analysis of LAT3 in prostate cancer: Its downstream target and relationship with androgen receptor

L‐type amino acid transporter 3 (LAT3, SLC43A1) is abundantly expressed in prostate cancer (PC) and is thought to play an essential role in PC progression through the cellular uptake of essential amino acids. Here, we analyzed the expression, function, and downstream target of LAT3 in PC. LAT3 was highly expressed in PC cells expressing androgen receptor (AR), and its expression was increased by dihydrotestosterone treatment and decreased by bicalutamide treatment. In chromatin immunoprecipitation sequencing of AR, binding of AR to the SLC43A1 region was increased by dihydrotestosterone stimulation. Knockdown of LAT3 inhibited cell proliferation, migration, and invasion, and the phosphorylation of p70S6K and 4EBP‐1. Separase (ESPL1) was identified as a downstream target of LAT3 by RNA sequencing analysis. In addition, immunostaining of prostatectomy specimens was performed. In the multivariate analysis, high expression of LAT3 was an independent prognostic factor for recurrence‐free survival (hazard ratio: 3.24; P = .0018). High LAT3 expression was correlated with the pathological T stage and a high International Society of Urological Pathology grade. In summary, our results suggest that LAT3 plays an important role in the progression of PC.

Cohesin Mutations in Cancer: Emerging Therapeutic Targets

The cohesin complex is crucial for mediating sister chromatid cohesion and for hierarchal three-dimensional organization of the genome. Mutations in cohesin genes are present in a range of cancers. Extensive research over the last few years has shown that cohesin mutations are key events that contribute to neoplastic transformation. Cohesin is involved in a range of cellular processes; therefore, the impact of cohesin mutations in cancer is complex and can be cell context dependent. Candidate targets with therapeutic potential in cohesin mutant cells are emerging from functional studies. Here, we review emerging targets and pharmacological agents that have therapeutic potential in cohesin mutant cells.

Circ-MMP2 (circ-0039411) induced by FOXM1 promotes the proliferation and migration of lung adenocarcinoma cells in vitro and in vivo

Numerous reports have stated the significance of cellular events such as proliferation, migration and EMT (epithelial-mesenchymal transition) for cancer development, but the related molecular mechanism remains elusive. FOXM1 (forkhead box transcription M1) is a nuclear co-activator participating in lung adenocarcinoma (LUAD). Thus, this study tried to explain the function of FOXM1 and its downstream molecular mechanism in LUAD. We uncovered FOXM1 upregulation in LUAD and demonstrated that FOXM1 facilitated β-catenin nuclear translocation to activate the transcription of downstream genes. Moreover, we discovered that FOXM1 transcriptionally activated circ0039411 which derived from matrix metallopeptidase 2 (MMP2) (also named as circ-MMP2), while MMP2 is a known downstream target of β-catenin. As for functional investigation, knockdown of circ-0039411 suppressed the proliferation, migration and EMT in LUAD cells and also hindered in vivo growth and metastasis of LUAD tumor. Mechanistically, circ-0039411 enhanced the stability of FOXM1 mRNA by recruiting IGF2BP3 (insulin like growth factor 2 mRNA binding protein 3), thus forming a positive feedback loop. In conclusion, this study revealed that FOXM1-induced circ-MMP2 (circ-0039411) contributes to malignant behaviors of LUAD cells via relying on FOXM1, potentially infusing inspirations for the search of new molecular targets for LUAD treatment.

The Analysis of the Anti-Tumor Mechanism of Ursolic Acid Using Connectively Map Approach in Breast Cancer Cells Line MCF-7

BACKGROUND

Ursolic acid (UA), a primary bioactive triterpenoid, was reported as an anti-cancer agent. However, the current knowledge of UA and its potential anti-cancer mechanisms and targets in breast cancer cells are limited. In this study, we aimed to illustrate the potential mechanisms and targets of UA in breast cancer cells MCF-7.

METHODS

The effect of UA on cell growth was determined in MCF-7 cells by MTT assay. The anti-tumor mechanism of UA was evaluated by microarray, CAMP, and Western blot. Moreover, the molecular docking between UA and potential receptors were predicted by iGEMDOCK software.

RESULTS

The result of MTT assay demonstrated that UA could inhibit MCF-7 cell growth with IC50 values of 20 μM. Microarray and CMAP analysis, validated by Western blot, indicated that UA significantly modulated IKK/NF-κB, RAF/ERK pathways, and down-regulated the phosphorylation level of PLK1 in MCF-7 cells.

CONCLUSION

Our data indicated that the anti-tumor effects of UA are due to the inhibited RAF/ERK pathway and IKK/NF-κB pathway. It could also be explained by the reduced phosphorylation of PLK1 in MCF-7 cells. This study provides a new insight for deep understanding of the new anti-cancer mechanisms of UA in MCF-7 breast cancer cells.

Stability and pharmacokinetics of separase inhibitor-Sepin-1 in Sprague-Dawley rats

Separase, a sister chromatid cohesion-resolving enzyme, is an oncogene and overexpressed in many human cancers. Sepin-1 (2,2-dimethyl-5-nitro-2H-benzimidazole-1,3-dioxide) is a potent separase inhibitor that impedes cancer cell growth, cell migration, and wound healing, suggesting that Sepin-1 possesses a great potential to target separase-overexpressing tumors. As a part of the IND-enabling studies to bring Sepin-1 to clinic, herein we report the results from a 28-day repeat-dose pharmacokinetic study of Sepin-1 in rats. Sepin-1 was intravenously administered to Sprague-Dawley rats once daily for 28 days at three different (5, 10, and 20 mg/kg) doses. Blood samples were collected after administration of doses on days 1 and 28. Sepin-1 is unstable and isomerizes in basic solutions, but it is stable in acidic buffer such as citrate-buffered saline (pH 4.0). UHPLC-MS analysis indicated Sepin-1 was rapidly metabolized in vivo. One of the major metabolites was an amine adduct of 2,2-dimethyl-5-nitro-2H-benzimidazole (named Sepin-1.55). The concentration of Sepin-1.55 in blood samples was Sepin-1 dose-dependent and used for pharmacokinetic analysis of Sepin-1. T_max was approximately 5-15 min. The data suggest that no Sepin-1 accumulation occurred from daily repeat dosing and similar exposures on the first and final day of dosing. Data also suggest a gender difference, namely that female rats have more exposure and slower clearance than male rats. The data support that Sepin-1 is a potential drug candidate that can be further developed to treat Separase-overexpressing human tumors.

Toxicity study of separase inhibitor-Sepin-1 in Sprague-Dawley rats

Sepin-1 is a small compound that inhibits enzymatic activity of Separase and growth of cancer cells. As part of the IND-enabling studies to develop Sepin-1 as a chemotherapeutic agent, herein we have profiled the toxicity of Sepin-1 in Sprague-Dawley rats in a good laboratory practice (GLP) setting. The maximum tolerated dose (MTD) of Sepin-1 in rats is 40 mg/kg in single dose study and 20 mg/kg in the study dosed for 7 consecutive days. The toxicity study consists of two parts-Main Study and Recovery Study. Sepin-1 with 0 (control), 5 (low dose), 10 (median dose), and 20 (high dose) mg/kg was administered by bolus intravenous injection to rats once daily for 28 consecutive days. The animals in the Main Study were euthanized on Day 29, whereas animals in the Recovery Study were allowed to recover for 28 days following the 28-day Sepin-1 dose before they were euthanized on Day 29 of the off-dose period. Although the effects of Sepin-1 at low and median doses are minimal, hematological analysis shows that high-dose Sepin-1 is associated with decrease of red blood cells and hemoglobin, and increase in the number of reticulocytes and platelets as well as mean corpuscular volume. Clinical chemistry indicates that Sepin-1 causes increase of total bilirubin and decrease of creatine kinase. Histopathology analysis indicates Sepin-1 results in minimal bone marrow erythroid hyperplasia, minimal to moderate splenic extramedullary hematopoiesis, minimal splenic lymphoid depletion, minimal to mild thymic lymphoid depletion, and minimal to mild mandibular lymph node lymphoid hyperplasia in male and female rats in the Main Study. Those abnormal changes are Sepin-1 dose-dependent and mostly reversible after a 28-day recovery period in animals from the Recovery Study. Based on our results, we conclude that Sepin-1 at pharmacologic doses (5-10 mg/kg) is well tolerable, with no significant rates of mortality or morbidity, and can further be developed as a potential new drug to treat Separase-overexpressed tumors.

Identification of Bioactive Small Molecule Inhibitors of Separase

Separase, a cysteine protease of the CD clan, triggers chromosome segregation during mitosis by cleaving the cohesin ring entrapping the two sister chromatids. Deregulated separase activity is associated with aneuploidy, a hallmark of most human cancers. In fact, separase is highly overexpressed in many solid cancers, making it an attractive chemotherapeutic target. To identify small molecules capable of inhibiting separase in its complex cellular environment, we established a highly sensitive assay to quantify separase activity in cells and screened a 51 009-member library for separase inhibitors. In vitro assays confirmed that the identified compounds efficiently inhibited separase, while not affecting caspase-1, another CD-clan protease structurally related to separase. Importantly, HeLa cells with compromised separase activity displayed severe chromosome segregation defects upon compound treatment, confirming that the identified inhibitors are bioactive in tumor tissue culture cells. Structure-activity relationship studies succeeded in the optimization of the most promising inhibitor. Overall, this study demonstrates the feasibility of identifying separase-specific inhibitors, which serve as promising lead compounds for the development of clinically relevant separase inhibiting drugs.

MiR-216b suppresses cell proliferation, migration, invasion, and epithelial-mesenchymal transition by regulating FOXM1 expression in human non-small cell lung cancer

Background/aims: MiR-216b and forkhead box M1 (FOXM1) were demonstrated to exert their biological effects on the development and progression of tumors. This study aimed to investigate the expression and role of miR-216b and FOXM1 in tissues and cell lines of non-small cell lung cancer (NSCLC). Methods: The expressions of miR-216b and FOXM1 in NSCLC tissues and cells were detected by qRT-PCR and Western blot analysis. Cell proliferation was measured by CCK-8 assay. Cell migration and invasion were confirmed by Transwell assay. Finally, the bioinformatics and dual-luciferase reporter assay were conducted to validate the relationship of miR-216b and FOXM1. Results: Compared with normal tissues and cells, the expression of miR-216b was obviously decreased in NSCLC tissues and cells. However, the expressions of FOXM1 mRNA and protein were significantly increased, and negatively correlated with the expression of miR-216b. Multivariate Cox's regression analysis suggested that miR-216b or FOXM1 expression was an independent prognostic factor for patients with NSCLC. MiR-216b overexpression remarkably repressed cell proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) of NSCLC cells. The bioinformatics and dual-luciferase reporter assay validated that the 3'-untranslated region (3'-UTR) of FOXM1 mRNA was indeed a direct target of FOXM1. In vitro, overexpression of FOXM1 partially eliminated inhibitory effects of miR-216b on cell proliferation, migration, and invasion, whereas inhibition of FOXM1 contributed to inhibitory effects mediated by miR-216b. Conclusion: MiR-216b inhibits cell proliferation, migration, invasion, and EMT by targeting the expression of FOXM1 in human NSCLC. These findings suggested a potential therapeutic role of miR-216b in patients of NSCLC.

hsa_circ_0061140 Knockdown Reverses FOXM1-Mediated Cell Growth and Metastasis in Ovarian Cancer through miR-370 Sponge Activity

Circular RNAs (circRNAs) are a class of noncoding RNAs that regulate gene expression at the posttranscriptional level. The specific functions of circRNAs in ovarian cancer are yet to be established. Previous sequencing analyses have revealed an abnormal expression of hsa_circ_0061140 in ovarian cancer. The main aim of the present study is to establish the specific role of hsa_circ_0061140 in ovarian cancer. circRNA expression in ovarian cancer cells was detected via real-time qPCR. The effects on specific cellular characteristics (proliferation, migration, and the EMT) and subcellular localization of hsa_circ_0061140 were assessed via RNA fluorescence in situ hybridization, knockdown, and luciferase reporter assays in the SKOV3 and A2780 cell lines. Tumorigenesis was induced in nude mice to assess the effects of hsa_circ_0061140 on ovarian cancer growth in vivo. Our results showed that hsa_circ_0061140 was upregulated in ovarian cancer cell lines. Knockdown of hsa_circ_0061140 suppressed cell proliferation and migration, both in vivo and in vitro, by inhibiting FOXM1 expression through sponging miR-370. Overexpression of FOXM1 or suppression of miR-370 rescued hsa_circ_0061140 silencing-induced inhibition of cell proliferation, migration, and the EMT. The associations among hsa_circ_0061140, miR-370, and FOXM1 were confirmed via bioinformatic prediction and fluorescein reporter experiments. Thus, hsa_circ_0061140 appeared to function as a competing endogenous RNA of miR-370 that promoted cell growth and metastasis in ovarian cancer through regulation of the miR-370/FOXM1 pathway mediating EMT.