Blockage of SSRP1/Ets-1/Pim-3 signalling enhances chemosensitivity of nasopharyngeal carcinoma to docetaxel in vitro

A review on structure-function mechanism and signaling pathway of serine/threonine protein PIM kinases as a therapeutic target

The proviral integration for the Moloney murine leukemia virus (PIM) kinases, belonging to serine/threonine kinase family, have been found to be overexpressed in various types of cancers, such as prostate, breast, colon, endometrial, gastric, and pancreatic cancer. The three isoforms PIM kinases i.e., PIM1, PIM2, and PIM3 share a high degree of sequence and structural similarity and phosphorylate substrates controlling tumorigenic phenotypes like proliferation and cell survival. Targeting short-lived PIM kinases presents an intriguing strategy as in vivo knock-down studies result in non-lethal phenotypes, indicating that clinical inhibition of PIM might have fewer adverse effects. The ATP binding site (hinge region) possesses distinctive attributes, which led to the development of novel small molecule scaffolds that target either one or all three PIM isoforms. Machine learning and structure-based approaches have been at the forefront of developing novel and effective chemical therapeutics against PIM in preclinical and clinical settings, and none have yet received approval for cancer treatment. The stability of PIM isoforms is maintained by PIM kinase activity, which leads to resistance against PIM inhibitors and chemotherapy; thus, to overcome such effects, PIM proteolysis targeting chimeras (PROTACs) are now being developed that specifically degrade PIM proteins. In this review, we recapitulate an overview of the oncogenic functions of PIM kinases, their structure, function, and crucial signaling network in different types of cancer, and the potential of pharmacological small-molecule inhibitors. Further, our comprehensive review also provides valuable insights for developing novel antitumor drugs that specifically target PIM kinases in the future. In conclusion, we provide insights into the benefits of degrading PIM kinases as opposed to blocking their catalytic activity to address the oncogenic potential of PIM kinases.

The FACT-targeted drug CBL0137 enhances the effects of rituximab to inhibit B-cell non-Hodgkin's lymphoma tumor growth by promoting apoptosis and autophagy

BACKGROUND

Aggressive B-cell non-Hodgkin's lymphoma (B-NHL) patients often develop drug resistance and tumor recurrence after conventional immunochemotherapy, for which new treatments are needed.

METHODS

We investigated the antitumor effects of CBL0137. In vitro, cell proliferation was assessed by CCK-8 and colony formation assay. Flow cytometry was performed to analyze cell cycle progression, apoptosis, mitochondrial depolarization, and reactive oxygen species (ROS) production. Autophagy was detected by transmission electron microscopy and mGFP-RFP-LC3 assay, while western blotting was employed to detect proteins involved in apoptosis and autophagy. RNA-sequencing was conducted to analyze the transcription perturbation after CBL0137 treatment in B-NHL cell lines. Finally, the efficacy and safety of CBL0137, rituximab, and their combination were tested in vivo.

RESULTS

CBL0137, a small molecule anticancer agent that has significant antitumor effects in B-NHL. CBL0137 sequesters the FACT (facilitates chromatin transcription) complex from chromatin to produce cytotoxic effects in B-NHL cells. In addition, we discovered novel anticancer mechanisms of CBL0137. CBL0137 inhibited human B-NHL cell proliferation by inducing cell cycle arrest in S phase via the c-MYC/p53/p21 pathway. Furthermore, CBL0137 triggers ROS generation and induces apoptosis and autophagy in B-NHL cells through the ROS-mediated PI3K/Akt/mTOR and MAPK signaling pathways. Notably, a combination of CBL0137 and rituximab significantly suppressed B-NHL tumor growth in subcutaneous models, consistent with results at the cellular level in vitro.

CONCLUSIONS

CBL0137 has potential as a novel approach for aggressive B-NHL, and its combination with rituximab can provide new therapeutic options for patients with aggressive B-NHL. Video Abstract.

Exosomes loaded with circPARD3 promotes EBV-miR-BART4-induced stemness and cisplatin resistance in nasopharyngeal carcinoma side population cells through the miR-579-3p/SIRT1/SSRP1 axis

OBJECTIVE

To explore the effects of exosomes loaded with circular RNA PARD3 on EBV-miR-BART4-induced stemness and resistance of cisplatin in nasopharyngeal carcinoma side population (NPC-SP) cells through the miR-579-3p/SIRT1/SSRP1 axis.

METHODS

Sixty-five cancer tissues and 65 noncancerous tissues were collected from NPC patients or patients with rhinitis. The expressions of circPARD3, miR-579-3p, SIRT1, and SSRP1 were detected by qRT-PCR, western blot, or immunohistochemistry. In vivo tumor formation assay was performed in nude mice. Immunofluorescence and qRT-PCR were conducted for the determination of CD44 and CD133 expressions, and flow cytometry combined with Hoechst 33,342 dye efflux for identifying SP cells, CCK-8 and EdU assays for cell proliferation, and Transwell assay for migration and invasion.

RESULTS

CircPARD3, SIRT1, and SSRP1 were upregulated while miR-579-3p was downregulated in NPC tissues and cells. CircPARD3 was positively correlated with the expressions of SIRT1 and SSRP1, and miR-579-3p was negatively correlated with circPARD3, SIRT1, and SSRP1. Exosomes loaded with circPARD3 promoted EBV-miR-BART4-induced stemness and cisplatin resistance in NPC-SP cells, while miR-579-3p reversed the effect of exosomal circPARD3 on EBV-miR-BART4-induced stemness and cisplatin resistance in NPC-SP cells. Additionally, miR-579-3p suppressed EBV-miR-BART4-induced stemness and cisplatin resistance in NPC-SP cells by regulating SIRT1. SIRT1 upregulated SSRP1 expression by catalyzing H3K4 methylation and down-regulation of SSRP1 reversed the effect of SIRT1 on EBV-miR-BART4-induced stemness and cisplatin resistance in NPC-SP cells.

CONCLUSION

Exosomes loaded with circPARD3 promoted EBV-miR-BART4-induced stemness and cisplatin resistance in NPC-SP cells through the miR-579-3p/SIRT1/SSRP1 axis. Graphical Headlights • EBV-miR-BART4 induces the stemness and resistance of NPC-SP cells. • CircPARD3 regulates SIRT1 by miR-579-3p. • SIRT1 regulates SSRP1 expression by histone methylation. • Exosomes loaded with circPARD3 promotes EBV-miR-BART4-induced NPC-SP cell stemness and resistance by the miR-579-3p/SIRT1/SSRP1 axis.

Global effects of RAB3GAP1 dysexpression on the proteome of mouse cortical neurons

Mounting studies have demonstrated that RAB3GAP1 expression is modified in brain diseases with multiple neurobiological functions and processes and acts as a potentially significant target. However, the cellular and molecular events arising from RAB3GAP1 dysexpression are still incompletely understood. In this work, underexpression and overexpression of RAB3GAP1 were first induced into cultured mouse cortical neurons by transfection with lentivirus plasmids. Then we globally explored the effects of RAB3GAP1 dysexpression on the proteome of the neurons through the use of isobaric tag for relative and absolute quantitation (iTRAQ)-based quantitative proteomics with bioinformatics. A total of 364 proteins in the RAB3GAP1-underexpression group and 314 proteins in the RAB3GAP1-overexpression group were identified to be differentially expressed. Subsequent bioinformatics analysis indicated that the proteome functional expression profiles induced by RAB3GAP1 underexpression and overexpression were different, suggesting the potential differences in biological processes and cellular effects. Subsequent intergroup cross-comparison revealed some candidate target proteins regulated directly by RAB3GAP1. Further parallel reaction monitoring (PRM) analysis illustrated that Sub1, Ssrp1, and Top1 proteins might serve as new potentially important linkers in the RAB3GAP1-mediated autophagy pathway in the cortical neurons. Collectively, the current proteomics data furnished new valuable insights to better understand the regulatory molecular mechanism of neuronal RAB3GAP1.

Effective inhibition of MYC-amplified group 3 medulloblastoma by FACT-targeted curaxin drug CBL0137

Medulloblastoma (MB) is the most common malignant pediatric brain tumor that can be categorized into four major molecular subgroups. Group 3 MB with MYC amplification (MYCamp-G3-MB) has been shown to be highly aggressive and exhibited worst prognosis, indicating the need for novel effective therapy most urgently. A few epigenetic targeted therapeutic strategies have recently been proven to effectively treat preclinical models of MYCamp-G3-MB, including BET inhibition, HDAC inhibition and SETD8 inhibition, unveiling a promising direction for further investigation. In this study, we carried out systemic bioinformatic analyses of public-available MB datasets as well as functional genomic screening datasets of primary MYCamp-G3-MB lines to search for other potential therapeutic targets within epigenetic modulators. We identified SSRP1, a subunit of histone-chaperone FACT complex, to be the top drug target candidate as it is highly cancer-dependent in whole-genome CRISPR-Cas9 screening across multiple MYCamp-G3-MB lines; significantly upregulated in MYCamp-G3-MB compared to normal cerebellum and most of the rest MB subtypes; its higher expression is correlated with worse prognosis; and it has a blood-brain-barrier penetrable targeted drug that has entered early phase human clinical trials already. Then we utilized RNA-interference approach to verify the cancer-dependency of SSRP1 in multiple MYCamp-G3-MB lines and further confirmed the therapeutic efficacy of FACT-targeted curaxin drug CBL0137 on treating preclinical models of MYCamp-G3-MB in vitro and in vivo, including an orthotopic intracranial xenograft model. Mechanistically, transcriptome analyses showed CBL0137 preferentially suppressed cell-cycle and DNA-repair related biological processes. Moreover, it selectively disrupted transcription of MYC and NEUROD1, two critical oncogenic transcription factors of MYCamp-G3-MB, via depleting FACT complex from their promoter regions. In summary, our study demonstrates FACT-targeted CBL0137 works effectively on treating MYCamp-G3-MB, presenting another promising epigenetic-targeted therapeutic strategy against the most devastating form of MB.

Long intergenic noncoding RNA01134 accelerates hepatocellular carcinoma progression by sponging microRNA-4784 and downregulating structure specific recognition protein 1

Dysregulation of long noncoding RNAs (lncRNAs) has been suggested to foster the carcinogenesis of hepatocellular carcinoma (HCC). To date, the role of long intergenic noncoding RNA01134 (LINC01134) in HCC have never been researched yet. Herein, we found that LINC01134 was highly expressed in HCC tissues in comparison with the matched normal liver tissues and increased LINC01134 expression correlated with shorter overall survival of patients with HCC. Additionally, we demonstrated LINC01134 downregulation significantly suppressed the proliferation ability and colony formation capacity of HCC cells. Furthermore, we revealed that LINC01134 functioned as a competitive endogenous RNA (ceRNA) for miR-4784 to upregulate structure-specific recognition protein 1 (SSRP1) in HCC cells. Meanwhile, miR-4784 inhibitor or restoration of SSRP1 could markedly attenuate the inhibitory effect of LINC01134 downregulation on HCC cells. Taken together, LINC01134 may promote the carcinogenesis of HCC at least partly via the miR-4784/SSRP1 axis. Therefore, LINC01134/miR-4784/SSRP1 axis should be developed as the promising therapeutic target for HCC.

MIR106A-5p upregulation suppresses autophagy and accelerates malignant phenotype in nasopharyngeal carcinoma

Dysregulated microRNAs (miRNAs) are involved in carcinoma progression, metastasis, and poor prognosis. We demonstrated that in nasopharyngeal carcinoma (NPC), transactivated MIR106A-5p promotes a malignant phenotype by functioning as a macroautophagy/autophagy suppressor by targeting BTG3 (BTG anti-proliferation factor 3) and activating autophagy-regulating MAPK signaling. MIR106A-5p expression was markedly increased in NPC cases based on quantitative real-time PCR, miRNA microarray, and TCGA database analysis findings. Moreover, MIR106A-5p was correlated with advanced stage, recurrence, and poor clinical outcomes in NPC patients. In addition to three-dimensional cell culture assays, zebrafish and BALB/c mouse tumor models revealed that overexpressed MIR106A-5p targeted BTG3 and accelerated the NPC malignant phenotype by inhibiting autophagy. BTG3 promoted autophagy, and its expression was correlated with poor prognosis in NPC. Attenuation of autophagy, mediated by the MIR106A-5p-BTG3 axis, occurred because of MAPK pathway activation. MIR106A-5p overexpression in NPC was due to increased transactivation by EGR1 and SOX9. Our findings may lead to novel insights into the pathogenesis of NPC.

Abbreviations: ACTB: actin beta; ATG: autophagy-related; ATG5: autophagy related 5; BLI: bioluminescence; BTG3: BTG anti-proliferation factor 3; CASP3: caspase 3; ChIP: chromatin immunoprecipitation; CQ: chloroquine; Ct: threshold cycle; DAPI: 4ʹ,6-diamidino-2-phenylindole; DiL: 1,1ʹ-dioctadecyl-3,3,3ʹ,3ʹ-tetramethylindocarbocyanine perchlorate; EBSS: Earle’s balanced salt solution; EGR1: early growth response 1; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GEO: Gene Expression Omnibus; GFP: green fluorescent protein; IF: immunofluorescence; IHC: immunohistochemistry; ISH: in situ hybridization; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; MIR106A-5p: microRNA 106a-5p; miRNAs: microRNAs; MKI67: marker of proliferation ki-67; mRNA: messenger RNA; MTOR: mechanistic target of rapamycin kinase; NPC: nasopharyngeal carcinoma; qRT-PCR: quantitative real-time PCR; siRNA: small interfering RNA; SOX9: SRY-box transcription factor 9; SQSTM1: sequestosome 1; TCGA: The Cancer Genome Atlas; WB: western blot.

Bufothionine exerts anti-cancer activities in gastric cancer through Pim3

AIM

Gastric cancer (GC) is the fourth most common cancer globally. Bufothionine is a major active constituent of Cinobufacini (Huachansu), which is extracted from the skin and parotid venom gland of the toad Bufo bufo gargarizans Cantor. It exhibits anti-cancer activities in vitro. However, whether bufothionine exerts anti-cancer activities against GC is unknown. This study was designed to evaluate the efficacy of bufothionine in vitro and in vivo.

MATERIAL AND METHODS

MKN28 and AGS cells were chosen as cell models to study the anti-cancer effect of bufothionine. Cell viability was determined by CCK-8 assay, while the effect of bufothionine on cell membrane integrity was examined by LDH assay. Cell apoptosis was detected by Hoechst/PI staining and Annexin V-FITC/PI staining followed by flow cytometry analysis. The expression levels of proteins involved were examined using western blotting. I-Traq analysis was conducted to identify the differentially expressed genes in AGS cells following bufothionine treatment. The anti-growth effect of bufothionine was validated in vivo using a GC xenograft model.

KEY FINDINGS

The results revealed that bufothionine prevented the growth, destroyed cell membrane and promoted apoptotic cell death of GC cells. iTRAQ analysis revealed thatPIM3 might be a molecular target responsible for the anti-cancer effects of bufothionine. It was also found that PIM3 knockdown significantly augmented the anti-growth and pro-apoptotic effects of bufothionine in GC cells. In contrast, ectopic PIM3 expression markedly dampened the anti-neoplastic activities of bufothionine. The expression of PIM3 was also suppressed by bufothionine treatment in xenograft tumor tissue.

SIGNIFICANCE

Bufothionine exhibited anti-cancer activities in vitro and in vivo in GC via downregulating PIM3.

A novel lncRNA LOC101927746 accelerates progression of colorectal cancer via inhibiting miR-584-3p and activating SSRP1

An increasing number of reports have indicated that long noncoding RNAs (lncRNAs) are involved in the pathogenesis of colorectal cancer (CRC). However, many lncRNAs remain unidentified in CRC, and their functions are yet to be elucidated. In this study, we investigated the function of lncRNA LOC101927746 in CRC progression. We found that LOC101927746 expression was significantly increased in CRC tissues according to the GEO dataset. Moreover, LOC101927746 expression was positively correlated with tumor stage and metastasis. Additionally, the high expression of LOC101927746 predicted poor prognosis in CRC patients. Functionally, we demonstrated that LOC101927746 silencing significantly suppressed the proliferation, migration, and invasion of CRC cells. In terms of its mechanism, LOC101927746 could serve as a competing endogenous RNA to inhibit miR-584-3p and activate its target gene SSRP1. The expression of miR-584-3p was inversely correlated with either LOC101927746 or SSRP1 in CRC tissues. The overexpression of SSRP1 or inhibition of miR-584-3p could reverse the effects of LOC101927746 knockdown in CRC cells. Taken together, our results suggest that the LOC101927746/miR-584-3p/SSRP1 axis modulates CRC progression.

Gallic Acid Inhibited Matrix Invasion and AP-1/ETS-1-Mediated MMP-1 Transcription in Human Nasopharyngeal Carcinoma Cells

Gallic acid is a trihydroxybenzoic acid found in natural herbal plants. Gallic acid has been reported to inhibit the migration and invasive capability of various cancers. Little is known about the underlying mechanisms of invasion responsible for cancer metastasis via gallic acid. The present study was intended to investigate the anti-invasive effect of gallic acid on human nasopharyngeal carcinoma cells (NPC-BM1) and its related mechanism. Gallic acid inhibited the invasion of NPC-BM1 cells dose- and time-dependently without significant cytotoxic effect. Affymetrix oligonucleotide microarray analysis revealed matrix metalloproteinase-1 (MMP-1) as the most down-regulated gene in NPC-BM1 cells by gallic acid. The cytosolic and secreted MMP-1 levels were both found to be inhibited by gallic acid as demonstrated by western blot analysis and ELISA respectively. The mRNA expression and transcription of MMP-1 gene was also down-regulated as determined by RT/real-time PCR and promoter activity assay. The expression of two major transcription binding factors in the MMP-1 promoter, AP-1 and ETS-1, were demonstrated to be reduced by gallic acid in NPC-BM1 cells. The effect of gallic acid was associated with the inhibition of p38 MAPK signaling pathway. In addition, gallic acid enhanced the gene expression of tissue inhibitor of matrix metalloproteinase-1 (TIMP-1) which further suppressed the MMP-1 activity. These findings may be useful to develop a novel chemotherapeutic agent to inhibit the metastasis of nasopharyngeal cancer.