Danusertib, a potent pan-Aurora kinase and ABL kinase inhibitor, induces cell cycle arrest and programmed cell death and inhibits epithelial to mesenchymal transition involving the PI3K/Akt/mTOR-mediated signaling pathway in human gastric cancer AGS and NCI-N78 cells

The Supression of Migration and Metastasis via Inhibition of Vascular Endothelial Growth Factor in Pancreatic Adenocarcinoma Cells Applied Danusertib

BACKGROUND/AIMS

Pancreatic ductal adenocarcinoma is an extremely deadly type of cancer with a high metastatic potential. Genetic factors in cellular events play an important role in the emergence of this situation. One of these factors is Aurora kinase family members, which play a role in migration, invasion, and cell cycle. In this study, the expression of vascular endothelial growth factor gene, which plays a role in migration, metastasis, and angiogenesis, on cystic fibrosis human pancreatic ductal adenocarcinoma 1 cells of danusertib, a pan-Aurora kinase inhibitor, was examined.

MATERIALS AND METHODS

The half maximal inhibitory concentration (IC50) value (400 nM) of danusertib in cystic fibrosis human pancreatic ductal adenocarcinoma 1 cells was determined by the wound-healing test depending on the dose and time and migration with CIM-Plate 16 in the xCELLingence system. In addition, the effect of danusertib on migration was determined by quantitative reverse transcription polymerase chain reaction (qRT-PCR) method and vascular endothelial growth factor gene expression.

RESULTS

When the dose- and time-dependent danusertib-applied cystic fibrosis human pancreatic ductal adenocarcinoma 1 cells were compared with the control group, it was observed that the wound formed did not close. In the xCELLigence system CIM-Plate 16 migration analysis, it was observed that migration was inhibited in the group administered danusertib in parallel with the wound dehiscence experiment. The gene expressions of vascular endothelial growth factor decreased 0.5-fold at the 24th hour and 0.3-fold at the 48th hour in the Danusertib-administered groups.

CONCLUSION

Danusertib, a pan-Aurora kinase inhibitor, is predicted to be used as a potential agent in pancreatic cancers due to its antitumor and anti-metastatic effect.

Aurora Kinase B Inhibition: A Potential Therapeutic Strategy for Cancer

Aurora kinase B (AURKB) is a mitotic serine/threonine protein kinase that belongs to the aurora kinase family along with aurora kinase A (AURKA) and aurora kinase C (AURKC). AURKB is a member of the chromosomal passenger protein complex and plays a role in cell cycle progression. Deregulation of AURKB is observed in several tumors and its overexpression is frequently linked to tumor cell invasion, metastasis and drug resistance. AURKB has emerged as an attractive drug target leading to the development of small molecule inhibitors. This review summarizes recent findings pertaining to the role of AURKB in tumor development, therapy related drug resistance, and its inhibition as a potential therapeutic strategy for cancer. We discuss AURKB inhibitors that are in preclinical and clinical development and combination studies of AURKB inhibition with other therapeutic strategies.

Bioinformatics Analysis Reveals an Association Between Cancer Cell Stemness, Gene Mutations, and the Immune Microenvironment in Stomach Adenocarcinoma

Cancer stem cells (CSCs), characterized by infinite proliferation and self-renewal, greatly challenge tumor therapy. Research into their plasticity, dynamic instability, and immune microenvironment interactions may help overcome this obstacle. Data on the stemness indices (mRNAsi), gene mutations, copy number variations (CNV), tumor mutation burden (TMB), and corresponding clinical characteristics were obtained from The Cancer Genome Atlas (TCGA) and UCSC Xena Browser. The infiltrating immune cells in stomach adenocarcinoma (STAD) tissues were predicted using the CIBERSORT method. Differentially expressed genes (DEGs) between the normal and tumor tissues were used to construct prognostic models with weighted gene co-expression network analysis (WGCNA) and Lasso regression. The association between cancer stemness, gene mutations, and immune responses was evaluated in STAD. A total of 6,739 DEGs were identified between the normal and tumor tissues. DEGs in the brown (containing 19 genes) and blue (containing 209 genes) co-expression modules were used to perform survival analysis based on Cox regression. A nine-gene signature prognostic model (ARHGEF38-IT1, CCDC15, CPZ, DNASE1L2, NUDT10, PASK, PLCL1, PRR5-ARHGAP8, and SYCE2) was constructed from 178 survival-related DEGs that were significantly related to overall survival, clinical characteristics, tumor microenvironment immune cells, TMB, and cancer-related pathways in STAD. Gene correlation was significant across the prognostic model, CNVs, and drug sensitivity. Our findings provide a prognostic model and highlight potential mechanisms and associated factors (immune microenvironment and mutation status) useful for targeting CSCs.

Augmentation of danusertib's anticancer activity against melanoma by blockage of autophagy

Previous evidence has shown that the increased expression of aurora kinase is closely related to melanoma progression and is an important therapeutic target in melanoma. Danusertib is an inhibitor of aurora kinase, and recent studies have shown that danusertib treatment induces autophagy in several types of cancer. Interestingly, autophagy plays a dual function in cancer as a pro-survival and anti-survival factor. In this study, we investigated the role of danusertib on the induction of autophagy in melanoma and determined the impact of autophagy induction on its anticancer activity against melanoma. Our results showed that danusertib can significantly inhibit melanoma growth by inducing cell cycle arrest and apoptosis. In addition, we demonstrated that danusertib treatment significantly inhibits the oncogenic Akt/mTOR signaling pathway and induces autophagy in melanoma cells. Furthermore, we identified that the inhibition of autophagy can enhance the inhibitory effects of danusertib on melanoma growth. Thus, the induction of autophagy by danusertib appears to be a survival mechanism in melanoma cells that may counteract its anticancer effects. These findings suggest a novel strategy to enhance the anticancer efficacy of danusertib in melanoma by blocking autophagy.

C1222C Deletion in Exon 8 of ABL1 Is Involved in Carcinogenesis and Cell Cycle Control of Colorectal Cancer Through IRS1/PI3K/Akt Pathway

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers worldwide. ABL1 (c-Abl) is a non-receptor tyrosine kinase, whose role, and molecular mechanism in CRC remain largely unclear. The aim of this study was to elucidate the role of ABL1 to obtain information on colon cancer gene mutation. We analyzed the tissue samples obtained from patients with CRC, CRC cell lines, and the immunodeficient mice. The proliferation, cell cycle, and apoptosis of CRC cells were examined. IPA software was used to analyze the molecules involved in CRC after ABL1 RNA interference. We found ABL1 was highly expressed in CRC tissues and cells. This high expression was associated with the TNM stage of CRC patients. In exon 8 of the ABL1 gene, we identified a novel mutation of C1222C deletion, which was related to the CRC stage. Depletion of ABL1 resulted in the inhibition of proliferation and escalation of apoptosis in two CRC cell lines, SW480, and HCT-116. Our in vivo study also demonstrated that depletion of ABL1 reduced CRC tumor progression. The results of the ingenuity pathway analysis indicated that the expression of 732 genes was upregulated and that of 691 genes was downregulated in mice transplanted with ABL1-downregulated CRC cells, among which we confirmed that depletion of ABL1 inhibited TGF-β1 via IRS1/PI3K/AKT pathway in CRC progression. These findings demonstrated that ABL1 plays an important role and that it can be a potential molecular target for CRC therapy.

Targeting E-cadherin expression with small molecules for digestive cancer treatment

Digestive system cancers, mainly including gastric cancer, hepatocellular carcinoma, pancreatic cancer, and colorectal cancer, are major public health problems and lead to serious cancer-related deaths worldwide. Clinically, treatment strategies of these cancers include surgery, chemotherapy, and immunotherapy. Although successful resection and chemotherapeutic drugs have improved the treatment level, the survival rate of patients with advanced digestive system cancers remains still low primarily due to tumor metastasis. E-cadherin, the prototypical member of the type-1 classical cadherins, has been characrized as an important molecule in epithelial-mesenchymal transition (EMT) process. Loss of E-cadherin is able to induce EMT process, which is associated with cancer stem cells and drug resistance in human cancer. Therefore, restoring E-cadherin could be a useful strategy for reversal of EMT and overcoming drug resistance. In this review, we describe pharmacological small molecules targeting E-cadherin expression for the treatment of digestive system cancers, which have emerged in the recent 5 years. We hope these compounds could be potentially used for treating cancer in the near future.

Clinical significance and biological roles of cyclins in gastric cancer

Background and aim

Cyclins have been reported to be overexpressed with poor prognosis in several human cancers. However, limited numbers of studies evaluated the expressions and prognostic roles of cyclins in gastric cancer (GC). We aim to evaluate the expressions and prognostic roles of cyclins. Also, further efforts were made to explore biological function of the differentially expressed cyclins.

Methods

Cyclins expressions were analyzed by Oncomine and The Cancer Genome Atlas datasets, and the prognostic roles of cyclins in GC patients were investigated by the Kaplan–Meier Plotter database. Then, a comprehensive PubMed literature search was performed to identify expression and prognosis of cyclins in GC. Biological functions of the differentially expressed cyclins were explored through Enrich R platform, and KEGG and transcription factor were analyzed.

Results

The expression levels of CCNA2 (cyclin A2), CCNB1 (cyclin B1), CCNB2 (cyclin B2), and CCNE1 (cyclin E1) mRNAs were identified to be significantly higher in GC tissues than in normal tissues in both Oncomine and The Cancer Genome Atlas datasets. High expressions of CCNA2, CCNB1, and CCNB2 mRNAs were identified to be related with poor overall survival in Kaplan–Meier Plotter dataset. Evidence from clinical studies showed that CCNB1 was related with overall survival in GC patients. Cyclins were associated with several biological pathways, including cell cycle, p53 signaling pathway, FoxO signaling pathway, viral carcinogenesis, and AMPK signaling pathway. Enrichment analysis also showed that cyclins interacted with some certain transcription factors, such as FOXM1, SIN3A, NFYA, and E2F4.

Conclusion

Based on our results, high expressions of cyclins were related with poor prognosis in GC patients. The above information might be useful for better understanding the clinical and biological roles of cyclins mRNA and guiding individualized treatments for GC patients.

Anticancer effect of resibufogenin on gastric carcinoma cells through the phosphoinositide 3-kinase/protein kinase B/glycogen synthase kinase 3β signaling pathway

The aim of the present study was to investigate the anticancer effect of resibufogenin in gastric carcinoma cells through the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/glycogen synthase kinase 3β (GSK3β) signaling pathway. MGC-803 cells were treated with 0, 1, 2, 4 and 8 µM resibufogenin for 12, 24 and 48 h. Cell viability and apoptosis were measured using an MTT assay and annexin V staining. Caspase-3 and caspase-8 activity were identified using caspase-3 and caspase-8 activity kits and a variety of protein expression [B cell lymphoma (Bcl)-2, Bcl-2-associated X protein (Bax), cyclin D1, cyclin E, PI3K, phosphorylated AKT, phosphorylated GSK3β and β-catenin] were quantified using western blot analysis. It was revealed that resibufogenin effectively inhibited cell proliferation, and induced apoptosis and caspase-3 and caspase-8 activity in MGC-803 cells. Furthermore, treatment with resibufogenin effectively increased Bax/Bcl-2 expression, and suppressed cyclin D1, cyclin E, PI3K, phosphorylated AKT, phosphorylated GSK3β and β-catenin protein expression in MGC-803 cells. These results suggest that the anticancer effect of resibufogenin induces gastric carcinoma cell death through the PI3K/AKT/GSK3β signaling pathway, offering a novel view of the mechanism by which resibufogenin functions as an agent to treat gastric carcinoma.

A quantitative proteomic response of hepatocellular carcinoma Hep3B cells to danusertib, a pan-Aurora kinase inhibitor

Hepatocellular carcinoma (HCC) is the sixth most common cancer worldwide, but the overall prognosis remains disappointing especially in the advanced-stage patients. Aberration expression of Aurora kinases is tumorigenic and thus it has attracted interests as therapeutic targets in cancer treatment. Here, we investigated the proteomic response of HCC Hep3B cells to danusertib (Danu), a pan-Aurora kinase inhibitor, and then validated the proteomic results based on stable-isotope labeling by amino acids in cell culture (SILAC). The proteomic data identified that Danu modulated the expression of 542 protein molecules (279 up-regulated; 260 down-regulated; 3 stable). Ingenuity pathway analysis (IPA) and KEGG pathway analysis identified 107 and 24 signaling pathways were regulated by Danu, respectively. IPA analysis showed cellular growth and proliferation, and cell death and survival were among the top five molecular and cellular functions regulated by Danu. The verification experiments showed that Danu inhibited the proliferation of Hep3B cells with a 24-hr IC50 value of 22.03 µM. Danu treatment also arrested Hep3B cells in G2/M phase via regulating the expression of key cell cycle regulators and induced apoptosis via mitochondria-dependent pathway in a dose-dependent manner. Besides, Danu induced a marked autophagy, and inhibition of autophagy enhanced the anticancer effects of Danu, indicating a cyto-protective role of Danu-induced autophagy. Our proteomic data and Western blotting assays showed the PI3K/Akt/mTOR signaling pathway was involved in the inducing effect of Danu on apoptosis and autophagy. Collectively, our findings have demonstrated that the Aurora kinases inhibition with danusertib results in global proteomic response and exerts anticancer effects in Hep3B cells involving regulation of cell cycle, apoptosis and autophagy and associated signaling pathways.

Systematic discovery of drug action mechanisms by an integrated chemical genomics approach: identification of functional disparities between azacytidine and decitabine

Polypharmacology (the ability of a drug to affect more than one molecular target) is considered a basic property of many therapeutic small molecules. Herein, we used a chemical genomics approach to systematically analyze polypharmacology by integrating several analytical tools, including the LINCS (Library of Integrated Cellular Signatures), STITCH (Search Tool for Interactions of Chemicals), and WebGestalt (WEB-based GEne SeT AnaLysis Toolkit). We applied this approach to identify functional disparities between two cytidine nucleoside analogs: azacytidine (AZA) and decitabine (DAC). AZA and DAC are structurally and mechanistically similar DNA-hypomethylating agents. However, their metabolism and destinations in cells are distinct. Due to their differential incorporation into RNA or DNA, functional disparities between AZA and DAC are expected. Indeed, different cytotoxicities of AZA and DAC toward human colorectal cancer cell lines were observed, in which cells were more sensitive to AZA. Based on a polypharmacological analysis, we found that AZA transiently blocked protein synthesis and induced an acute apoptotic response that was antagonized by concurrently induced cytoprotective autophagy. In contrast, DAC caused cell cycle arrest at the G₂/M phase associated with p53 induction. Therefore, our study discriminated functional disparities between AZA and DAC, and also demonstrated the value of this chemical genomics approach that can be applied to discover novel drug action mechanisms.

ATG7 Overexpression Is Crucial for Tumorigenic Growth of Bladder Cancer In Vitro and In Vivo by Targeting the ETS2/miRNA196b/FOXO1/p27 Axis

Human bladder cancer (BC) is the fourth most common cancer in the United States. Investigation of the strategies aiming to elucidate the tumor growth and metastatic pathways in BC is critical for the management of this disease. Here we found that ATG7 expression was remarkably elevated in human bladder urothelial carcinoma and N-butyl-N-(4-hydroxybutyl)nitrosamine (BBN)-induced mouse invasive BC. Knockdown of ATG7 resulted in a significant inhibitory effect on tumorigenic growth of human BC cells both in vitro and in vivo by promoting p27 expression and inducing cell cycle arrest at G2/M phase. We further demonstrated that knockdown of ATG7 upregulated FOXO1 (forkhead box protein O 1) expression, which specifically promoted p27 transcription. Moreover, mechanistic studies revealed that inhibition of ATG7 stabilized ETS2 mRNA and, in turn, reduced miR-196b transcription and expression of miR-196b, which was able to bind to the 3' UTR of FOXO1 mRNA, consequently stabilizing FOXO1 mRNA and finally promoting p27 transcription and attenuating BC tumorigenic growth. The identification of the ATG7/FOXO1/p27 mechanism for promoting BC cell growth provides significant insights into understanding the nature of BC tumorigenesis. Together with our most recent discovery of the crucial role of ATG7 in promoting BC invasion, it raises the potential for developing an ATG7-based specific therapeutic strategy for treatment of human BC patients.

miR-340 Inhibits Proliferation and Induces Apoptosis in Gastric Cancer Cell Line SGC-7901, Possibly via the AKT Pathway

BACKGROUND Gastric cancer is among the most common types of cancer, with high morbidity and mortality. MicroRNAs (miRNAs) play vital roles in the tumorigenesis and biology of gastric cancer. This study aimed to reveal the role of miR-340 in gastric cancer cell proliferation and apoptosis and to elucidate the potential mechanisms. MATERIAL AND METHODS Human gastric cancer cells SGC-7901 were used in this study for cell transfection with miR-340 mimic or inhibitor. After transfection, cell viability, proliferation, and apoptosis were examined by MTT, BrdU, and flow cytometry assays, respectively. The protein level changes of p27, p21, Caspase 3 (CASP3), B cell lymphoma 2 (BCL2), BCL2-associated X protein (BAX), and v-AKT murine thymoma viral oncogene (AKT) were detected by Western blot. RESULTS Overexpression of miR-340 significantly reduced cell viability and proliferation (P<0.01), and induced cell apoptosis (P<0.01) of SGC-7901. miR-340 elevated the protein level of cell cycle inhibitor p27, but did not affect the level of p21. Apoptosis-related factors pro-CASP3, cleaved-CASP3, and BAX were promoted, and BCL2 was inhibited by miR-340. miR-340 also suppressed the phosphorylation of AKT. Opposite effects were detected when SGC-7901 cells were transfected with miR-340 inhibitor. CONCLUSIONS These results indicate that miR-340 can inhibit proliferation and induce apoptosis of SGC-7901 cells, suggesting its roles in protecting against gastric cancer. The roles of miR-340 in gastric cancer cells may be associated with its regulation of the AKT pathway. Thus, miR-340 may be a potential therapeutic strategy for gastric cancer treatment.

A protein and mRNA expression-based classification of gastric cancer

The overall survival of gastric carcinoma patients remains poor despite improved control over known risk factors and surveillance. This highlights the need for new classifications, driven towards identification of potential therapeutic targets. Using sophisticated molecular technologies and analysis, three groups recently provided genetic and epigenetic molecular classifications of gastric cancer (The Cancer Genome Atlas, 'Singapore-Duke' study, and Asian Cancer Research Group). Suggested by these classifications, here, we examined the expression of 14 biomarkers in a cohort of 146 gastric adenocarcinomas and performed unsupervised hierarchical clustering analysis using less expensive and widely available immunohistochemistry and in situ hybridization. Ultimately, we identified five groups of gastric cancers based on Epstein-Barr virus (EBV) positivity, microsatellite instability, aberrant E-cadherin, and p53 expression; the remaining cases constituted a group characterized by normal p53 expression. In addition, the five categories correspond to the reported molecular subgroups by virtue of clinicopathologic features. Furthermore, evaluation between these clusters and survival using the Cox proportional hazards model showed a trend for superior survival in the EBV and microsatellite-instable related adenocarcinomas. In conclusion, we offer as a proposal a simplified algorithm that is able to reproduce the recently proposed molecular subgroups of gastric adenocarcinoma, using immunohistochemical and in situ hybridization techniques.

Low Expression of CDK5 and p27 Are Associated with Poor Prognosis in Patients with Gastric Cancer

Several previous studies have demonstrated that CDK5 or p27 expression in gastric cancer are associated with overall survival. We have previously reported that tumor suppressive function of CDK5 is related to p27. The aim of this study was to investigate correlation between the clinicopathological parameters and overall survival with different CDK5/p27 expression statuses in 244 gastric cancer patients using immunohistochemistry. Low CDK5 expression was detected in 93 cases (38.11%) and low p27 in 157 cases (64.34%). The expression of CDK5 was significantly related to sex (P = 0.034) and Lauren's classification (P = 0.013). The expression of p27 was significantly related to sex (P = 0.012), differentiation (P = 0.003), TNM stage (P = 0.013) and lymph node metastasis (P = 0.001). Based on the combined expression of CDK5 and p27, we classified the patients into four subtypes: CDK5 Low/p27 Low (n = 69), CDK5 High/p27 Low (n = 88), CDK5 Low/p27 High (n = 24) and CDK5 High/p27 High (n = 63). The CDK5 Low/p27 Low expression was closely related to female (P = 0.026), diffuse type (P = 0.027) and lymph node metastasis (P = 0.010). The CDK5 Low/p27 Low patients displayed poorer survival in comparison with the rest of the patients in Kaplan-Meier analysis. No significant overall survival difference was observed among the patients with CDK5 High and/or p27 High expression. In the multivariate analysis, CDK5 and p27 co-expression status was identified as an independent prognostic factor for patients with gastric cancer.

Epithelial-mesenchymal transition in gastric cancer

Gastric cancer (GC) is one of the most common malignancies worldwide with poor prognosis for lack of early detection and effective treatment modalities. The significant influence of tumor microenvironment on malignant cells has been extensively investigated in this targeted-therapy era. Epithelial-mesenchymal transition (EMT) is a highly conserved and fundamental process that is critical for embryogenesis and some other pathophysiological processes, especially tumor genesis and progression. Aberrant gastric EMT activation could endow gastric epithelial cells with increased mesenchymal characteristics and less epithelial features, and promote cancer cell stemness, initiation, invasion, metastasis, and chemo-resistance with cellular adhesion molecules especially E-cadherin concomitantly repressed, which allows tumor cells to disseminate and spread throughout the body. Some pathogens, stress, and hypoxia could induce and aggravate GC via EMT, which is significantly correlated with prognosis. GC EMT is modulated by diverse micro-environmental, membrane, and intracellular cues, and could be triggered by various overexpressed transcription factors, which are downstream of several vital cross-talking signaling pathways including TGF-β, Wnt/β-catenin, Notch, etc. microRNAs also contribute significantly to GC EMT modulation. There are currently some agents which could suppress GC EMT, shedding light on novel anti-malignancy strategies. Investigating potential mechanisms modulating GC cell EMT and discovering novel EMT regulators will further elucidate GC biology, and may provide new biomarkers for early GC detection and potentially efficient targets for preventative and curative anti-GC intervention approaches to prevent local and distant invasions.

Danusertib Induces Apoptosis, Cell Cycle Arrest, and Autophagy but Inhibits Epithelial to Mesenchymal Transition Involving PI3K/Akt/mTOR Signaling Pathway in Human Ovarian Cancer Cells

Ovarian carcinoma (OC) is one of the most common gynecological malignancies, with a poor prognosis for patients at advanced stage. Danusertib (Danu) is a pan-inhibitor of the Aurora kinases with unclear anticancer effect and underlying mechanisms in OC treatment. This study aimed to examine the cancer cell killing effect and explore the possible mechanisms with a focus on proliferation, cell cycle progression, apoptosis, autophagy, and epithelial to mesenchymal transition (EMT) in human OC cell lines C13 and A2780cp. The results showed that Danu remarkably inhibited cell proliferation, induced apoptosis and autophagy, and suppressed EMT in both cell lines. Danu arrested cells in G₂/M phase and led to an accumulation of polyploidy through the regulation of the expression key cell cycle modulators. Danu induced mitochondria-dependent apoptosis and autophagy in dose and time-dependent manners. Danu suppressed PI3K/Akt/mTOR signaling pathway, evident from the marked reduction in the phosphorylation of PI3K/Akt/mTOR, contributing to the autophagy inducing effect of Danu in both cell lines. In addition, Danu inhibited EMT. In aggregate, Danu exerts potent inducing effect on cell cycle arrest, apoptosis, and autophagy, but exhibits a marked inhibitory effect on EMT. PI3K/Akt/mTOR signaling pathway contributes, partially, to the cancer cell killing effect of Danu in C13 and A2780cp cells.

Celastrol induces cell cycle arrest by MicroRNA-21-mTOR-mediated inhibition p27 protein degradation in gastric cancer

Objective

Celastrol has anti-cancer effects by increase of apoptosis of gastric cancer cells. However, its role in gastric cancer cell cycle is still unclear. The aim of this study was to investigate the effect and mechanism of celastrol on gastric cancer cell cycle.

Methods

The effects of celastrol on cell cycle in BGC-823 and MGC-803 cells were assayed via flow cytometry analysis. The expression of p27 and mTOR was detected by real-time PCR and western blot. The activity of mTOR and mTORC2 was measured by mTOR and mTORC2 kinase assays. miR-21 mimic was used to up-regulate miR-21 expression and mTOR expression plasmid was used to increase mTOR level in gastric cancer cells.

Results

Celastrol caused G2/M cell-cycle arrest that was accompanied by the down-regulation of miR-21 expression. In particular, miR-21 overexpression reversed cell cycle arrest effects of celastrol. Further study showed that celastrol increased levels of the p27 protein by inhibiting its degradation. miR-21 and mTOR signaling pathway was involved in the increase of p27 protein expression in BGC-823 and MGC-803 cells treated with celastrol. Significantly, miR-21 overexpression restored the decrease of mTOR activity in cells exposed celastrol.

Conclusions

The effect of celastrol on cell cycle arrest of gastric cancer cells was due to an increase of p27 protein level via inhibiting miR-21-mTOR signaling pathway.