Restoring PUMA induction overcomes KRAS-mediated resistance to anti-EGFR antibodies in colorectal cancer

Antitumor Effect of Apcin on Endometrial Carcinoma via p21-Mediated Cell Cycle Arrest and Apoptosis

OBJECTIVE

Endometrial carcinoma (EC) is a prevalent gynecological malignancy characterized by increasing incidence and mortality rates. This underscores the critical need for novel therapeutic targets. One such potential target is cell division cycle 20 (CDC20), which has been implicated in oncogenesis. This study investigated the effect of the CDC20 inhibitor Apcin on EC and elucidated the underlying mechanism involved.

METHODS

The effects of Apcin on EC cell proliferation, apoptosis, and the cell cycle were evaluated using CCK8 assays and flow cytometry. RNA sequencing (RNA-seq) was subsequently conducted to explore the underlying molecular mechanism, and Western blotting and coimmunoprecipitation were subsequently performed to validate the results. Animal studies were performed to evaluate the antitumor effects in vivo. Bioinformatics analysis was also conducted to identify CDC20 as a potential therapeutic target in EC.

RESULTS

Treatment with Apcin inhibited proliferation and induced apoptosis in EC cells, resulting in cell cycle arrest. Pathways associated with apoptosis and the cell cycle were activated following treatment with Apcin. Notably, Apcin treatment led to the upregulation of the cell cycle regulator p21, which was verified to interact with CDC20 and consequently decrease the expression of downstream cyclins in EC cells. In vivo experiments confirmed that Apcin treatment significantly impeded tumor growth. Higher CDC20 expression was observed in EC tissue than in nonmalignant tissue, and increased CDC20 expression in EC patients was associated with shorter overall survival and progress free interval.

CONCLUSION

CDC20 is a novel molecular target in EC, and Apcin could be developed as a candidate antitumor drug for EC treatment.

PUMA/RIP3 Mediates Chemotherapy Response via Necroptosis and Local Immune Activation in Colorectal Cancer

Induction of programmed cell death (PCD) is a key cytotoxic effect of anticancer therapies. PCD is not confined to caspase-dependent apoptosis, but includes necroptosis, a regulated form of necrotic cell death controlled by receptor-interacting protein (RIP) kinases 1 and 3, and mixed lineage kinase domain-like (MLKL) pseudokinase. Necroptosis functions as a defense mechanism against oncogenic mutations and pathogens and can be induced by a variety of anticancer agents. However, the functional role and regulatory mechanisms of necroptosis in anticancer therapy are poorly understood. In this study, we found that RIP3-dependent but RIP1-independent necroptosis is engaged by 5-fluorouracil (5-FU) and other widely used antimetabolite drugs, and functions as a major mode of cell death in a subset of colorectal cancer cells that express RIP3. We identified a novel 5-FU-induced necroptosis pathway involving p53-mediated induction of the BH3-only Bcl-2 family protein, p53 upregulated modulator of apoptosis (PUMA), which promotes cytosolic release of mitochondrial DNA and stimulates its sensor z-DNA-binding protein 1 (ZBP1) to activate RIP3. PUMA/RIP3-dependent necroptosis mediates the in vitro and in vivo antitumor effects of 5-FU and promotes a robust antitumor immune response. Our findings provide a rationale for stimulating necroptosis to enhance tumor cell killing and antitumor immune response leading to improved colorectal cancer treatments.

Targeting KRAS in Colorectal Cancer: A Bench to Bedside Review

Colorectal cancer (CRC) is a heterogeneous disease with a myriad of alterations at the cellular and molecular levels. Kristen rat sarcoma (KRAS) mutations occur in up to 40% of CRCs and serve as both a prognostic and predictive biomarker. Oncogenic mutations in the KRAS protein affect cellular proliferation and survival, leading to tumorigenesis through RAS/MAPK pathways. Until recently, only indirect targeting of the pathway had been investigated. There are now several KRAS allele-specific inhibitors in late-phase clinical trials, and many newer agents and targeting strategies undergoing preclinical and early-phase clinical testing. The adequate treatment of KRAS-mutated CRC will inevitably involve combination therapies due to the existence of robust adaptive resistance mechanisms in these tumors. In this article, we review the most recent understanding and findings related to targeting KRAS mutations in CRC, mechanisms of resistance to KRAS inhibitors, as well as evolving treatment strategies for KRAS-mutated CRC patients.

Targeting Myc-driven stress addiction in colorectal cancer

MYC is a proto-oncogene that encodes a powerful regulator of transcription and cellular programs essential for normal development, as well as the growth and survival of various types of cancer cells. MYC rearrangement and amplification is a common cause of hematologic malignancies. In epithelial cancers such as colorectal cancer, genetic alterations in MYC are rare. Activation of Wnt, ERK/MAPK, and PI3K/mTOR pathways dramatically increases Myc levels through enhanced transcription, translation, and protein stability. Elevated Myc promotes stress adaptation, metabolic reprogramming, and immune evasion to drive cancer development and therapeutic resistance through broad changes in transcriptional and translational landscapes. Despite intense interest and effort, Myc remains a difficult drug target. Deregulation of Myc and its targets has profound effects that vary depending on the type of cancer and the context. Here, we summarize recent advances in the mechanistic understanding of Myc-driven oncogenesis centered around mRNA translation and proteostress. Promising strategies and agents under development to target Myc are also discussed with a focus on colorectal cancer.

The EXTREME Regimen Associating Cetuximab and Cisplatin Favors Head and Neck Cancer Cell Death and Immunogenicity with the Induction of an Anti-Cancer Immune Response

(1) Background: The first line of treatment for recurrent/metastatic Head and Neck Squamous Cell Carcinoma (HNSCC) has recently evolved with the approval of immunotherapies that target the anti-PD-1 immune checkpoint. However, only about 20% of the patients display a long-lasting objective tumor response. The modulation of cancer cell immunogenicity via a treatment-induced immunogenic cell death is proposed to potentially be able to improve the rate of patients who respond to immune checkpoint blocking immunotherapies. (2) Methods: Using human HNSCC cell line models and a mouse oral cancer syngeneic model, we have analyzed the ability of the EXTREME regimen (combination therapy using the anti-EGFR cetuximab antibody and platinum-based chemotherapy) to modify the immunogenicity of HNSCC cells. (3) Results: We showed that the combination of cetuximab and cisplatin reduces cell growth through both cell cycle inhibition and the induction of apoptotic cell death independently of p53. In addition, different components of the EXTREME regimen were found to induce, to a variable extent, and in a cell-dependent manner, the emission of mediators of immunogenic cell death, including calreticulin, HMGB1, and type I Interferon-responsive chemokines. Interestingly, cetuximab alone or combined with the IC₅₀ dose of cisplatin can induce an antitumor immune response in vivo, but not when combined with a high dose of cisplatin. (4) Conclusions: Our observations suggest that the EXTREME protocol or cetuximab alone are capable, under conditions of moderate apoptosis induction, of eliciting the mobilization of the immune system and an anti-tumor immune response in HNSCC.

DPCPX induces Bim-dependent apoptosis in nasopharyngeal carcinoma cells

ADORA1 promotes tumor growth and development in multiple cancers. DPCPX (a selective adenosine A1 receptor antagonist), a specific ADORA1 antagonist, has shown antitumor effects in many cancer types. Nevertheless, the function of DPCPX in nasopharyngeal carcinoma (NPC) still remains to be unraveled. In this study, we investigated the functional role of DPCPX on NPC cells. We found that DPCPX promotes NPC cells growth inhibition. DPCPX induced Bim-dependent apoptosis in NPC cells irrespective of p53 status via the FoxO3a pathway following PI3K/AKT inhibition. Furthermore, DPCPX enhanced the antitumor effect of cisplatin, 5-FU and Paclitaxel in NPC. Xenograft experiment revealed that deficiency of Bim in vivo stalls apoptosis and antitumor activity of DPCPX. In conclusion, the PI3K/AKT/FoxO3a/Bim axis plays a critical role in the anticancer effects of DPCPX in NPC.

CDK4/6 Inhibition Suppresses p73 Phosphorylation and Activates DR5 to Potentiate Chemotherapy and Immune Checkpoint Blockade

Targeting cyclin-dependent kinases 4 and 6 (CDK4/6) is a successful therapeutic approach against breast and other solid tumors. Inhibition of CDK4/6 halts cell cycle progression and promotes antitumor immunity. However, the mechanisms underlying the antitumor activity of CDK4/6 inhibitors are not fully understood. We found that CDK4/6 bind and phosphorylate the p53 family member p73 at threonine 86, which sequesters p73 in the cytoplasm. Inhibition of CDK4/6 led to dephosphorylation and nuclear translocation of p73, which transcriptionally activated death receptor 5 (DR5), a cytokine receptor and key component of the extrinsic apoptotic pathway. p73-mediated induction of DR5 by CDK4/6 inhibitors promoted immunogenic cell death of cancer cells. Deletion of DR5 in cancer cells in vitro and in vivo abrogated the potentiating effects of CDK4/6 inhibitors on immune cytokine TRAIL, 5-fluorouracil chemotherapy, and anti-PD-1 immunotherapy. Together, these results reveal a previously unrecognized consequence of CDK4/6 inhibition, which may be critical for potentiating the killing and immunogenic effects on cancer cells.

SIGNIFICANCE

This work demonstrates how inhibition of CDK4/6 sensitizes cancer cells to chemotherapy and immune checkpoint blockade and may provide a new molecular marker for improving CDK4/6-targeted cancer therapies. See related commentary by Frank, p. 1170.

TRIM24 promotes colorectal cancer cell progression via the Wnt/β-catenin signaling pathway activation

Overexpression of TRIM24 is observed in several human cancers and is correlated with an increase in the progression and metastasis of tumors. In this study, we investigated the changes in activity and biochemical events that occur after overexpression of TRIM24 in a colorectal cancer (CRC) mouse model. We observed upregulated TRIM24 expression in CRC tissues compared to that in nonneoplastic adjacent tissues. Enhanced expression of TRIM24 was significantly associated with the status of lymph nodes and poor recurrence-free survival of patients with CRC. The role of TRIM24 in CRC tumor growth was investigated using an orthotopic model of MC38 mouse colon cancer cells overexpressing TRIM24, and CRC tumor growth was found to increase dramatically by TRIM24 overexpression. Moreover, angiogenesis was stimulated by TRIM24 overexpression via the upregulation of vascular endothelial growth factor (VEGF) expression. Overexpression of TRIM24 in MC38 cells led to an increase in the protein levels of ALDH1 and other stem cell markers. In addition, we observed that Wnt/β-catenin signaling is required for the function of TRIM24 in CRC cells. Tumor-associated macrophages (TAMs) were found to be recruited by tumor cells overexpressing TRIM24 via the increased expression of CCL2/5, CSF-1, and VEGF, further enhancing CRC tumor growth. In conclusion, overexpression of TRIM24 facilitates the growth of CRC and the remodeling of the tumor stroma via angiogenesis stimulation and TAM recruitment. The Wnt/β-catenin pathway is a possible crucial link in the TRIM24-associated progression of tumors, which may provide opportunities for pharmacological intervention.

RAS-mediated tumor stress adaptation and the targeting opportunities it presents

Cellular stress is known to function in synergistic cooperation with oncogenic mutations during tumorigenesis to drive cancer progression. Oncogenic RAS is a strong inducer of a variety of pro-tumorigenic cellular stresses, and also enhances the ability of cells to tolerate these stresses through multiple mechanisms. Many of these oncogenic, RAS-driven, stress-adaptive mechanisms have also been implicated in tolerance and resistance to chemotherapy and to therapies that target the RAS pathway. Understanding how oncogenic RAS shapes cellular stress adaptation and how this functions in drug resistance is of vital importance for identifying new therapeutic targets and therapeutic combinations to treat RAS-driven cancers.

BRD9 inhibition promotes PUMA-dependent apoptosis and augments the effect of imatinib in gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GISTs) are primarily characterized by activating mutations of tyrosine kinase or platelet-derived growth factor receptor alpha. Although the revolutionary therapeutic outcomes of imatinib are well known, the long-term benefits of imatinib are still unclear. The effects of BRD9, a recently identified subunit of noncanonical BAF complex (ncBAF) chromatin remodeling complexes, in GISTs are not clear. In the current study, we evaluated the functional role of BRD9 in GIST progression. Our findings demonstrated that the expression of BRD9 was upregulated in GIST tissues. The downregulation or inhibition of BRD9 could significantly reduce cellular proliferation, and facilitates apoptosis in GISTs. BRD9 inhibition could promote PUMA-dependent apoptosis in GISTs and enhance imatinib activity in vitro and in vivo. BRD9 inhibition synergizes with imatinib in GISTs by inducing PUMA upregulation. Mechanism study revealed that BRD9 inhibition promotes PUMA induction via the TUFT1/AKT/GSK-3β/p65 axis. Furthermore, imatinib also upregulates PUMA by targeting AKT/GSK-3β/p65 axis. In conclusion, our results indicated that BRD9 plays a key role in the progression of GISTs. Inhibition of BRD9 is a novel therapeutic strategy in GISTs treated alone or in combination with imatinib.

ADORA1 promotes nasopharyngeal carcinoma cell progression through regulation of PI3K/AKT/GSK-3β/β-catenin signaling

AIMS

For most human cancers, the expression pattern and biological function of ADORA1 (Adenosine A1 Receptor) are largely unknown. This study has been designed to explore the clinical significance and the mechanism of ADORA1 in nasopharyngeal carcinoma (NPC) cells.

MATERIALS AND METHODS

The level of ADORA1 in NPC and its adjacent tissues was analyzed by IHC, real-time PCR and western blotting. MTT and colony formation assays were used to determine the cell viability post ADORA1 overexpression or knockdown. Wound-healing assay and Transwell assay were used to analyze the effect of ADORA1 on migration and invasion. Moreover, the effect of ADORA1 on tumor growth was also studied in vivo by using xenograft mouse model. The regulation of ADORA1 on PI3K/AKT/GSK-3β/β-catenin pathway was determined by western blotting and TOP-Flash luciferase assay.

KEY FINDINGS

Primary NPC exhibits overexpression of ADORA1, which is related to the overexpression of its mRNA. Ectopic expression of ADORA1 promotes the proliferation, invasion and migration in NPC cells. The apoptosis, however, is suppressed. ADORA1 silencing was found to exert opposite effects in in vitro studies and produced a significant inhibitory effect on murine xenograft tumor growth in vivo experiments. Besides, ADORA1 also triggers the PI3K/AKT/GSK-3β/β-catenin intracellular oncogenic pathway for signal transduction. Inhibition of this pathway by PI3K inhibitor LY294002 obstructed the impact of ADORA1 on tumor development in cells with ADORA1-overexpression.

SIGNIFICANCE

ADORA1 has been identified as an important oncoprotein, promoting tumor cell proliferation via PI3K/AKT/GSK-3β/β-catenin signaling pathway in NPC.

Non-steroidal anti-inflammatory drugs induce immunogenic cell death in suppressing colorectal tumorigenesis

Use of non-steroidal anti-inflammatory drugs (NSAIDs) is associated with reduced risk of colorectal cancer (CRC). However, the mechanism by which NSAIDs suppress colorectal tumorigenesis remains unclear. We previously showed that NSAIDs selectively kill emerging tumor cells via death receptor (DR) signaling and a synthetic lethal interaction mediated by the proapoptotic Bcl-2 family protein BID. In this study, we found NSAIDs induce endoplasmic reticulum (ER) stress to activate DR signaling and BID in tumor suppression. Importantly, our results unveiled an ER stress- and BID-dependent immunogenic effect of NSAIDs, which may be critical for tumor suppression. NSAID treatment induced hallmarks of immunogenic cell death (ICD) in CRC cells and colonic epithelial cells upon loss of APC tumor suppressor, and elevated tumor-infiltrating lymphocytes (TILs) in the polyps of APCMin/+ mice. ER stress inhibition or BID deletion abrogated the antitumor and immunogenic effects of NSAIDs. Furthermore, increased ER stress and TILs were detected in human advanced adenomas from NSAID-treated patients. Together, our results suggest that NSAIDs induce ER stress- and BID-mediated ICD to restore immunosurveillance and suppress colorectal tumor formation.

Copanlisib promotes growth inhibition and apoptosis by modulating the AKT/FoxO3a/PUMA axis in colorectal cancer

Colorectal cancer (CRC) is the type of cancer with the third highest incidence and is associated with high mortality and low 5-year survival rates. We observed that copanlisib, an inhibitor of PI3K (pan-class I phosphoinositide 3-kinase) that preferentially inhibits PI3Kδ and PI3Kα, impedes the growth of CRC cells by inducing apoptosis via PUMA. There was a marked increase in the expression of PUMA independent of p53 after treatment with copanlisib. The response of CRC cells to copanlisib could be predicted by PUMA expression. Copanlisib was found to induce PUMA expression through FoxO3a by directly binding to the PUMA promoter after inhibiting AKT signaling. PUMA deficiency mitigated the apoptosis induced by copanlisib. Caspase activation and mitochondrial dysfunction led to copanlisib resistance, as observed through a clonogenic assay, whereas enhanced expression of PUMA increased the copanlisib-induced susceptibility to apoptosis. Moreover, the antitumor effects of copanlisib were suppressed by a deficiency of PUMA in a xenograft model, and caspase activation and reduced apoptosis were also observed in vivo. Copanlisib-mediated chemosensitization seemed to involve the concurrent induction of PUMA expression via mechanisms that were both dependent and independent of p53. These observations indicate that apoptosis mediated by PUMA is crucial for the anticancer effects of copanlisib and that manipulation of PUMA may aid in enhancing anticancer activities.

BET degrader inhibits tumor progression and stem-like cell growth via Wnt/β-catenin signaling repression in glioma cells

Based on their histological appearance, gliomas are a very common primary tumor type of the brain and are classified into grades, Grade I to Grade IV, of the World Health Organization. Treatment failure is due to the cancer stem cells (CSC) phenotype maintenance and self-renewal. BET degraders such as ZBC260 represents a novel class of BET inhibitors that act by inducing BET proteins degradation. This study explores the mode of action and effects of ZBC260 in vivo and in vitro against glioma. By inhibiting cell proliferation and inducting cell cycle arrest, the fact that glioma cell lines show sensitivity to ZBC260. Notably, ZBC260 targeted glioma without side effects in vivo. In addition, the stem cell-like properties of glioma cells were inhibited upon ZBC260 treatment. When the mechanism was examined, our findings indicated that Wnt/β-catenin pathway repression is required for ZBC260-induced stem cell-like properties and tumor growth suppression. In conclusion, the growth of tumors and stem cell-like properties were inhibited by ZBC260 via Wnt/β-catenin repression, which suggests ZBC260 as a potential therapeutic agent for glioma.

UCHL3 promotes proliferation of colorectal cancer cells by regulating SOX12 via AKT/mTOR signaling pathway

OBJECTIVE

The dysregulation of deubiquitinating enzymes is important in the development of many cancers, including colorectal cancer (CRC). However, the precise function and potential mode of action of the deubiquitinating enzyme UCHL3 in CRC progression are poorly elucidated.

METHODS

The expression levels of UCHL3 in patient samples were analyzed by western blotting, real-time PCR and immunohistochemistry and its association with overall survival was analyzed using Kaplan-Meier method. Colony formation, CCK-8 and Transwell were used to examine the effects of UCHL3 knockdown or over-expression on CRC cells growth, invasion and migration. The functional effects of UCHL3 and SOX12 on tumor growth were further examined using xenograft tumor mouse models in vivo.

RESULTS

Here, we found high expression of UCHL3 in CRC tissues which showed an association with the development of tumor and CRC patient survival. Studies conducted in vitro showed that UCHL3 overexpression facilitates proliferation, invasion, migration, and EMT (epithelial-mesenchymal transition) in cells of CRC, and a knockdown of UCHL3 had a reverse effect. Likewise, experiments conducted in vivo also showed enhanced tumor growth due to UCHL3 overexpression. In addition, UCHL3 was found regulates SOX12 expression in CRC cells. PI3K/AKT/mTOR pathway is required for UCHL3-mediated SOX12 expression. Mechanically, UCHL3 regulates SOX12 via AKT/mTOR signaling pathway and facilitated tumor progression.

CONCLUSION

UCHL3 plays an oncogenic role through the AKT/mTOR/SOX12 axis and can be considered as a potential target for therapy and CRC prognostic biomarker.

AMPK activation overcomes anti-EGFR antibody resistance induced by KRAS mutation in colorectal cancer

Background

Colorectal cancer (CRC) is associated with resistance to anti-epidermal growth factor receptor (EGFR) antibodies (both acquired and intrinsic), owing to the amplification or mutation of the KRAS oncogene. However, the mechanism underlying this resistance is incompletely understood.

Methods

DLD1 cells with WT (+/−) or KRAS G13D mutant allele were treated with different concentrations of Cetuximab (Cet) or panitumumab (Pab) to study the mechanism underlying the KRAS mutation-induced resistance to anti-EGFR antibodies. The function of AMPK in KRAS mutation-induced resistance to anti-EGFR antibodies in CRC cells, and the regulatory role of Bcl-2 family proteins in DLD1 cells with WT or mutated KRAS upon AMPK activation were investigated. In addition, xenograft tumor models with the nude mouse using DLD1 cells with WT or mutated KRAS were established to examine the effects of AMPK activation on KRAS mutation-mediated anti-EGFR antibody resistance.

Results

Higher levels of AMPK activity in CRC cells with wild-type KRAS treated with anti-EGFR antibody resulted in apoptosis induction. In contrast, CRC cells with mutated KRAS showed lower AMP-activated protein kinase (AMPK) activity and decreased sensitivity to the inhibitory effect of anti-EGFR antibody. CRC cells with mutated KRAS showed high levels of glycolysis and produced an excessive amount of ATP, which suppressed AMPK activation. The knockdown of AMPK expression in CRC cells with WT KRAS produced similar effects to those observed in cells with mutated KRAS and decreased their sensitivity to cetuximab. On the contrary, the activation of AMPK by metformin (Met) or 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) could overcome the KRAS-induced resistance to the anti-EGFR antibody in vivo and in vitro. The activation of AMPK resulted in the inhibition of myeloid cell leukemia 1 (Mcl-1) translation through the suppression of the mammalian target of rapamycin (mTOR) pathway.

Conclusion

The results established herein indicate that targeting AMPK is a potentially promising and effective CRC treatment strategy.

Mcl-1 inhibition overcomes intrinsic and acquired regorafenib resistance in colorectal cancer

Intrinsic and acquired resistance to targeted therapies is a significant clinical problem in cancer. We previously showed that resistance to regorafenib, a multi-kinase inhibitor for treating colorectal cancer (CRC) patients, can be caused by mutations in the tumor suppressor FBW7, which block degradation of the pro-survival Bcl-2 family protein Mcl-1. We tested if Mcl-1 inhibition can be used to develop a precision combination therapy for overcoming regorafenib resistance.

METHODS

Small-molecule Mcl-1 inhibitors were tested on CRC cells with knock-in (KI) of a non-degradable Mcl-1. Effects of Mcl-1 inhibitors on regorafenib sensitivity were determined in FBW7-mutant and -wild-type (WT) CRC cells and tumors, and in those with acquired regorafenib resistance due to enriched FBW7 mutations. Furthermore, translational potential was explored by establishing and analyzing FBW7-mutant and -WT patient-derived organoid (PDO) and xenograft (PDX) tumor models.

RESULTS

We found that highly potent and specific Mcl-1 inhibitors such as S63845 overcame regorafenib resistance by restoring apoptosis in multiple regorafenib-resistant CRC models. Mcl-1 inhibition re-sensitized CRC tumors with intrinsic and acquired regorafenib resistance in vitro and in vivo, including those with FBW7 mutations. Importantly, Mcl-1 inhibition also sensitized FBW7-mutant PDO and PDX models to regorafenib. In contrast, Mcl-1 inhibition had no effect in FBW7-WT CRCs.

CONCLUSIONS

Our results demonstrate that Mcl-1 inhibitors can overcome intrinsic and acquired regorafenib resistance in CRCs by restoring apoptotic response. FBW7 mutations might be a potential biomarker predicting for response to the regorafenib/Mcl-1 inhibitor combination.

Lestaurtinib potentiates TRAIL-induced apoptosis in glioma via CHOP-dependent DR5 induction

Lestaurtinib, also called CEP-701, is an inhibitor of tyrosine kinase, causes haematological remission in patients with AML possessing FLT3-ITD (FLT3 gene) internal tandem duplication and strongly inhibits tyrosine kinase FLT3. Treatment with lestaurtinib modulates various signalling pathways and leads to cell growth arrest and programmed cell death in several tumour types. However, the effect of lestaurtinib on glioma remains unclear. In this study, we examined lestaurtinib and TRAIL interactions in glioma cells and observed their synergistic activity on glioma cell apoptosis. While U87 and U251 cells showed resistance to TRAIL single treatment, they were sensitized to apoptosis induced by TRAIL in the presence of lestaurtinib because of increased death receptor 5 (DR5) levels through CHOP-dependent manner. We also demonstrated using a xenograft model of mouse that the tumour growth was absolutely suppressed because of the combined treatment compared to TRAIL or lestaurtinib treatment carried out singly. Our findings reveal a potential new strategy to improve antitumour activity induced by TRAIL in glioma cells using lestaurtinib through a mechanism dependent on CHOP.

CDK4/6 inhibition suppresses tumour growth and enhances the effect of temozolomide in glioma cells

In adults, glioma is the most commonly occurring and invasive brain tumour. For malignant gliomas, the current advanced chemotherapy includes TMZ (temozolomide). However, a sizeable number of gliomas are unyielding to TMZ, hence, giving rise to an urgent need for more efficient treatment choices. Here, we report that cyclin-dependent kinases 4 (CDK4) is expressed at significantly high levels in glioma cell lines and tissues. CDK4 overexpression enhances colony formation and proliferation of glioma cells and extends resistance to inhibition of TMZ-mediated cell proliferation and induction of apoptosis. However, CDK4 knockdown impedes colony formation and cell proliferation, and enhances sensitivity of glioma cells to TMZ. The selective inhibition of CDK4/6 impedes glioma cell proliferation and induces apoptotic induction. The selective inhibitors of CDK4/6 may enhance glioma cell sensitivity to TMZ. We further showed the possible role of RB phosphorylation mediated by CDK4 for its oncogenic function in glioma. The growth of glioma xenografts was inhibited in vivo, through combination treatment, and corresponded to enhanced p-RB levels, reduced staining of Ki-67 and enhanced activation of caspase 3. Therefore, CDK4 inhibition may be a favourable strategy for glioma treatment and overcomes TMZ resistance.

MicroRNA-155-3p promotes glioma progression and temozolomide resistance by targeting Six1

The prognosis of glioma is generally poor and is the cause of primary malignancy in the brain. The role of microRNAs has been implicated in tumour inhibition or activation. In several cancers, the Six1 signalling pathway has been found to be aberrant and also relates to the formation of tumours. We analysed the database for expression profiles and clinical specimens of various grades of glioma to assess microRNA-155-3p (miR-155-3p) expression. The role of miR-155-3p in glioblastoma, cell cycle, proliferation, apoptosis and resistance to temozolomide was assessed in vitro through flow cytometry and cell proliferation assays. Bioinformatics analyses, and assays using luciferase reporter, and immunoblotting revealed that miR-155-3p targets Six1 and that the relationship between glioma and healthy brain tissues was significantly inverse. In rescue experiments, overexpressed Six1 revoked the changes in cell cycle distribution, proliferation and resistance to temozolomide estimated by apoptosis induced by overexpressed miR-155-3p. MiR-155-3p inhibition reduced glioma cell growth and proliferation in the brain of a mouse model and increased the survival of mice with gliomas. Thus, miR-155-3p modulates Six1 expression and facilitates the progression of glioblastoma and resistance to temozolomide and may act as a novel diagnostic biomarker and a target for glioma treatment.

Trametinib potentiates TRAIL-induced apoptosis via FBW7-dependent Mcl-1 degradation in colorectal cancer cells

Trametinib is a MEK1/2 inhibitor and exerts anticancer activity against a variety of cancers. However, the effect of Trametinib on colorectal cancer (CRC) is not well understood. In the current study, our results demonstrate the ability of sub-toxic doses of Trametinib to enhance TRAIL-mediated apoptosis in CRC cells. Our findings also indicate that Trametinib and TRAIL activate caspase-dependent apoptosis in CRC cells. Moreover, Mcl-1 overexpression can reduce apoptosis in CRC cells treated with Trametinib with or without TRAIL. We further demonstrate that Trametinib degrades Mcl-1 through the proteasome pathway. In addition, GSK-3β phosphorylates Mcl-1 at S159 and promotes Mcl-1 degradation. The E3 ligase FBW7, known to polyubiquitinate Mcl-1, is involved in Trametinib-induced Mcl-1 degradation. Taken together, these results provide the first evidence that Trametinib enhances TRAIL-mediated apoptosis through FBW7-dependent Mcl-1 ubiquitination and degradation.

MiR-3116 sensitizes glioma cells to temozolomide by targeting FGFR1 and regulating the FGFR1/PI3K/AKT pathway

Glioma is a brain tumour that is often diagnosed, and temozolomide (TMZ) is a common chemotherapeutic drug used in glioma. Yet, resistance to TMZ is a chief hurdle towards curing the malignancy. The current work explores the pathways and involvement of miR-3116 in the TMZ resistance. miR-3116 and FGFR1 mRNA were quantified by real-time PCR in malignant samples and cell lines. Appropriate assays were designed for apoptosis, viability, the ability to form colonies and reporter assays to study the effects of the miR-3116 or FGFR1. The involvement of PI3K/AKT signalling was assessed using Western blotting. Tumorigenesis was evaluated in an appropriate xenograft mouse model in vivo. This work revealed that the levels of miR-3116 dipped in samples resistant to TMZ, while increased miR-3116 caused an inhibition of the tumour features mentioned above to hence augment TMZ sensitivity. miR-3116 was found to target FGFR1. When FGFR1 was overexpressed, resistance to TMZ was augmented and reversed the sensitivity caused by miR-3116. Our findings further confirmed PI3K/AKT signalling pathway is involved in this action. In conclusion, miR-3116 sensitizes glioma cells to TMZ through FGFR1 downregulation and the PI3K/AKT pathway inactivation. Our results provide a strategy to overcome TMZ resistance in glioma treatment.

Immunogenic cell death in colon cancer prevention and therapy

Colorectal cancer (CRC) is a leading cause of cancer-related death worldwide. The colonic mucosa constitutes a critical barrier and a major site of immune regulation. The immune system plays important roles in cancer development and treatment, and immune activation caused by chronic infection or inflammation is well-known to increase cancer risk. During tumor development, neoplastic cells continuously interact with and shape the tumor microenvironment (TME), which becomes progressively immunosuppressive. The clinical success of immune checkpoint blockade therapies is limited to a small set of CRCs with high tumor mutational load and tumor-infiltrating T cells. Induction of immunogenic cell death (ICD), a type of cell death eliciting an immune response, can therefore help break the immunosuppressive TME, engage the innate components, and prime T cell-mediated adaptive immunity for long-term tumor control. In this review, we discuss the current understanding of ICD induced by antineoplastic agents, the influence of driver mutations, and recent developments to harness ICD in colon cancer. Mechanism-guided combinations of ICD-inducing agents with immunotherapy and actionable biomarkers will likely offer more tailored and durable benefits to patients with colon cancer.

miR-1254 inhibits progression of glioma in vivo and in vitro by targeting CSF-1

The role of miRNAs (microRNAs) has been implicated in glioma initiation and progression, although the inherent biochemical mechanisms still remain to be unravelled. This study strived to evaluate the association between CSF-1 and miR-1254 and their effect on advancement of glioma cells. The levels of miR-1254 in glioma cells and tissues were determined by real-time RT-PCR. Proliferation, apoptosis and cell cycle arrest, invasion and migration, were assessed by CCK-8 assay, colony formation assay, flow cytometry, transwell assay and wound-healing assay, respectively. The targeted relationship between miR-1254 and CSF-1 was confirmed by dual-luciferase reporter assay. The effects of CSF-1 on cellular functions were also assessed. The in vivo effect of miR-1254 on the formation of a tumour was explored by using the mouse xenograft model. We found in both glioma tissues and glioma cells, the down-regulated expressions of miR-1254 while that of CSF-1 was abnormally higher than normal level. The target relationship between CSF-1 and miR-1254 was validated by dual-luciferase reporter assay. The CSF-1 down-regulation or miR-1254 overexpression impeded the invasion, proliferation and migratory ability of U251 and U87 glioma cells, concurrently occluded the cell cycle and induced cell apoptosis. Moreover, in vivo tumour development was repressed due to miR-1254 overexpression. Thus, CSF-1 is targeted directly by miR-1254, and the miR-1254/CSF-1 axis may be a potential diagnostic target for malignant glioma.

Gilteritinib induces PUMA-dependent apoptotic cell death via AKT/GSK-3β/NF-κB pathway in colorectal cancer cells

As a highly potent and highly selective oral inhibitor of FLT3/AXL, gilteritinib showed activity against FLT3D835 and FLT3‐ITD mutations in pre‐clinical testing, although its role on colorectal cancer (CRC) cells is not yet fully elucidated. We examined the activity of gilteritinib in suppressing growth of CRC and its enhancing effect on other drugs used in chemotherapy. In this study, we observed that, regardless of p53 status, treatment using gilteritinib induces PUMA in CRC cells via the NF‐κB pathway after inhibition of AKT and activation of glycogen synthase kinase 3β (GSK‐3β). PUMA was observed to be vital for apoptosis in CRC cells through treatment of gilteritinib. Moreover, enhancing induction of PUMA through different pathways could mediate chemosensitization by using gilteritinib. Furthermore, PUMA deficiency revoked the antitumour role of gilteritinib in vivo. Thus, our results indicate that PUMA mediates the antitumour activity of gilteritinib in CRC cells. These observations are critical for the therapeutic role of gilteritinib in CRC.

miR-20a regulates inflammatory in osteoarthritis by targeting the IκBβ and regulates NK-κB signaling pathway activation

In the cartilage and synovial microenvironment of osteoarthritis (OA) patients, utmost changes are commonly brought upon by the inflammatory cytokines, leading to cellular dysfunction, particularly in chondrocytes. The regulation of chondrogenesis, a key part is played the microRNAs. Thus, the current study aimed to assess the function of miR-20a in osteoarthritis. The miR-20a expression was observed to increase in the tissues of OA cartilage, when compared with tissues of normal cartilage, and enhanced proliferation of chondrocyte was observed in the presence of miR-20a. Moreover, on treating the chondrocytes with LPS (lipopolysaccharide), an increase in miR-20a level was observed. On transfecting with miR-20a inhibitor, inhibition in production of LPS-induced pro-inflammatory cytokines as well as cell apoptosis were seen. The assay for luciferase activity showed that the expression of IκBβ was impeded on being targeted at its 3'-UTR by miR-20a. The transfection of IκBβ and inhibitor of miR-20a repressed the NF-κB pathway activation and chondrocyte cellular apoptosis. An OA model was established for in vivo studies on rats by ACLT (anterior cruciate ligament transection). In conclusion, the results demonstrate an increase in articular cavity inflammation in rats with OA in the presence of miR-20a by targeting on IκBβ and activating the NF-κB signaling pathway.

Cabozantinib induces PUMA-dependent apoptosis in colon cancer cells via AKT/GSK-3β/NF-κB signaling pathway

Cabozantinib is a multi-kinase inhibitor targeting MET, AXL, and VEGFR2, and has been approved for use in multiple malignancies. The means by which Cabozantinib acts to target colorectal cancer (CRC) cells remains poorly understood, and we sought to investigate how this drug disrupts cell growth in CRC cells and how it interacts to enhance the efficacy of other chemotherapeutic agents. In this study, we found that Cabozantinib activated a p65-dependent signaling pathway in response to both inhibition of AKT and activation of glycogen synthase kinase 3β (GSK3β), leading to upregulation of PUMA in CRC cells regardless of p53 activity. PUMA upregulation facilitates CRC apoptosis in response to Cabozantinib, which also acts synergistically with the chemotherapeutic agents Cetuximab and 5-FU to induce robust apoptosis in a PUMA-dependent manner. Eliminating PUMA expression ablated this apoptosis induced by Cabozantinib in xenograft mouse model. Our findings revealed that Cabozantinib acts to drive CRC cells apoptosis via a PUMA-dependent mechanism, thus identifying PUMA expression as a potential predictor of Cabozantinib efficacy and a potential novel therapeutic target.

Encorafenib inhibits migration, induces cell cycle arrest and apoptosis in colorectal cancer cells

Encorafenib, a new-generation BRAF inhibitor, has been approved by FDA for the treatment of melanoma in combination with binimetinib. However, the mechanism of the drug works in colorectal cancer (CRC) is still unclear. In this study, the suppression of growth of CRC cells by encorafenib was investigated. The effects of treatment of encorafenib on pathways linked to cancer were studied, and the effective inhibition of cell proliferation was documented. Our findings showed that cell migration was inhibited by encorafenib through a likely involvement of MPP and TIMP modulation. Furthermore, encorafenib treatment also induced cell cycle arrest. In addition, induction of apoptosis in CRC cells by elevating levels of PUMA. These observations indicate the potential therapeutic efficacy of encorafenib on CRC.

The anticancer effects of cinobufagin on hepatocellular carcinoma Huh‑7 cells are associated with activation of the p73 signaling pathway

The Na⁺/K⁺-ATPase inhibitor cinobufagin exhibits numerous anticancer effects on hepatocellular carcinoma (HCC) cells expressing wild-type p53 via inhibition of aurora kinase A (AURKA) and activation of p53 signaling. However, the effects of cinobufagin on HCC cells expressing mutant p53 remain unclear. In the present study, the anticancer effects of cinobufagin were investigated on HCC Huh-7 cells with mutant p53, and the effects of AURKA overexpression or inhibition on the anticancer effects of cinobufagin were analyzed. Viability, cell cycle progression and apoptosis of cells were determined using an MTT assay, flow cytometry and Hoechst 33342 staining, respectively. The expression levels of p53 and p73 signaling-associated proteins were investigated via western blot analysis. The results demonstrated that the expression levels of AURKA, B-cell lymphoma 2 (Bcl-2), cyclin-dependent kinase 1, cyclin B1, proliferating cell nuclear antigen and heterogeneous nuclear ribonucleoprotein K, as well as the phosphorylation of p53 and mouse double minute 2 homolog, were significantly decreased in Huh-7 cells treated with 5 µmol/l cinobufagin for 24 h. Conversely, the expression levels of Bcl-2-associated X protein, p21, p53 upregulated modulator of apoptosis and phorbol-12-myristate-13-acetate-induced protein 1, were significantly increased by cinobufagin treatment. Overexpression or inhibition of AURKA suppressed or promoted the anticancer effects of cinobufagin on Huh-7 cells, respectively. These results indicated that cinobufagin may induce anticancer effects on Huh-7 cells via the inhibition of AURKA and p53 signaling, and via the activation of p73 signaling, in an AURKA-dependent manner.

BET inhibitor I-BET151 sensitizes GBM cells to temozolomide via PUMA induction

A significant roadblock in treatment of GBM multiforme (GBM) is resistance to temozolomide (TMZ). In this study, we investigated whether I-BET151, a specific BET inhibitor, could sensitize GBM cells to TMZ. Our findings showed that the action of I-BET151 could augment the effect of TMZ on cancer cells U251 and U87 cells. In U251 cells, administration of I-BET151 increased the TMZ-induced apoptosis GBM cells. I-BET151 remarkably enhanced the activities of caspase-3. In addition, I-BET151 promoted TMZ-induced migration and invasion in GBM cells. Moreover, I-BET151 increased the amount of reactive oxygen species as well as superoxide anions with a decrease of activity of SOD and the anti-oxidative properties of GBM cells. I-BET151 also induced increased PUMA expression, which is required for the functions of I-BET151 and regulates the synergistic cytotoxic effects of i-BET151 and TMZ in GBM cells. I-BET151 with TMZ also showed synergistic cytotoxic effects in vivo. These point out to an approach to tackle GBM using TMZ along with BET inhibitors.