BET Inhibitors Potentiate Chemotherapy and Killing of SPOP-Mutant Colon Cancer Cells via Induction of DR5

A novel DDIT3 activator dehydroevodiamine effectively inhibits tumor growth and tumor cell stemness in pancreatic cancer

BACKGROUND

The existence of pancreatic cancer stem cells (PCSCs) results in limited survival benefits from current treatment options. There is a scarcity of effective agents for treating pancreatic cancer patients. Dehydroevodiamine (DeHE), a quinazoline alkaloid isolated from the traditional Chinese herb Evodiae fructus, exhibited potent inhibition of pancreatic ductal adenocarcinoma (PDAC) cell proliferation and tumor growth both in vitro and in vivo.

METHODS

The cytotoxic effect of DeHE on PDAC cells was assessed using CCK-8 and colony formation assays. The antitumor efficacy of DeHE were appraised in human PANC-1 xenograft mouse model. Sphere formation assay and flow cytometry were employed to quantify the tumor stemness. RNA-Seq analysis, drug affinity responsive target stability assay (DARTS), and RNA interference transfection were conducted to elucidate potential signaling pathways. Western blotting and immunohistochemistry were utilized to assess protein expression levels.

RESULTS

DeHE effectively inhibited PDAC cell proliferation and tumor growth in vitro and in vivo, and exhibited a better safety profile compared to the clinical drug gemcitabine (GEM). DeHE inhibited PCSCs, as evidenced by its suppression of self-renewal capabilities of PCSCs, reduced the proportion of ALDH+ cells and downregulated stemness-associated proteins (Nanog, Sox-2, and Oct-4) both in vitro and in vivo. Furthermore, there is potential involvement of DDIT3 and its downstream DDIT3/TRIB3/AKT/mTOR pathway in the suppression of stemness characteristics within DeHE-treated PDAC cells. Additionally, results from the DARTS assay indicated that DeHE interacts with DDIT3, safeguarding it against degradation mediated by pronase. Notably, the inhibitory capabilities of DeHE on PDAC cell proliferation and tumor stemness were partially restored by siDDIT3 or the AKT activator SC-79.

CONCLUSION

In summary, our study has identified DeHE, a novel antitumor natural product, as an activator of DDIT3 with the ability to suppress the AKT/mTOR pathway. This pathway is intricately linked to tumor cell proliferation and stemness characteristics in PDAC. These findings suggest that DeHE holds potential as a promising candidate for the development of innovative anticancer therapeutics.

Triazoles in Medicinal Chemistry: Physicochemical Properties, Bioisosterism, and Application

Triazole demonstrates distinctive physicochemical properties, characterized by weak basicity, various dipole moments, and significant dual hydrogen bond acceptor and donor capabilities. These features are poised to play a pivotal role in drug-target interactions. The inherent polarity of triazole contributes to its lower logP, suggesting the potential improvement in water solubility. The metabolic stability of triazole adds additional value to drug discovery. Moreover, the metal-binding capacity of the nitrogen atom lone pair electrons of triazole has broad applications in the development of metal chelators and antifungal agents. This Perspective aims to underscore the unique physicochemical attributes of triazole and its application. A comparative analysis involving triazole isomers and other heterocycles provides guiding insights for the subsequent design of triazoles, with the hope of offering valuable considerations for designing other heterocycles in medicinal chemistry.

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.

Bromodomain and extraterminal (BET) proteins: biological functions, diseases, and targeted therapy

BET proteins, which influence gene expression and contribute to the development of cancer, are epigenetic interpreters. Thus, BET inhibitors represent a novel form of epigenetic anticancer treatment. Although preliminary clinical trials have shown the anticancer potential of BET inhibitors, it appears that these drugs have limited effectiveness when used alone. Therefore, given the limited monotherapeutic activity of BET inhibitors, their use in combination with other drugs warrants attention, including the meaningful variations in pharmacodynamic activity among chosen drug combinations. In this paper, we review the function of BET proteins, the preclinical justification for BET protein targeting in cancer, recent advances in small-molecule BET inhibitors, and preliminary clinical trial findings. We elucidate BET inhibitor resistance mechanisms, shed light on the associated adverse events, investigate the potential of combining these inhibitors with diverse therapeutic agents, present a comprehensive compilation of synergistic treatments involving BET inhibitors, and provide an outlook on their future prospects as potent antitumor agents. We conclude by suggesting that combining BET inhibitors with other anticancer drugs and innovative next-generation agents holds great potential for advancing the effective targeting of BET proteins as a promising anticancer strategy.

Activation of endoplasmic reticulum stress by harmine suppresses the growth of esophageal squamous cell carcinoma

The worldwide overall 5-year survival rate of esophageal squamous cell carcinoma (ESCC) patients is less than 20%, and novel therapeutic strategies for these patients are urgently needed. Harmine is a natural β-carboline alkaloid, which received great interest in cancer research because of its biological and anti-tumor activities. The aim of this study is to examine the effects of harmine on ESCC and its mechanism. We investigated the effects of harmine on proliferation, cell cycle, apoptosis, and tumor growth in vivo. RNA sequencing (RNA-seq), real-time PCR, and western blotting were used to detect the mechanism. Harmine inhibited ESCC cell growth in vitro and tumor growth in vivo. Differentially expressed genes in harmine-treated ESCC cells were mainly involved in protein processing in the endoplasmic reticulum (ER). Real-time PCR and western blotting confirmed harmine-induced cellular ER stress. CRISPR-Cas9 knockout of C/EBP homologous protein (CHOP) abolished harmine-induced expression of death receptor 5 and apoptosis. Harmine also induced the expression of CHOP-mediated sestrin-2, which in turn contributes to autophagosome formation via suppressing the AMP-activated protein kinase-protein kinase B-mammalian target of rapamycin signaling pathway. In conclusion, our results demonstrate that harmine inhibits the growth of ESCC through its regulation of ER stress, suggesting that it is a promising candidate for ESCC treatment.

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.

Patient-derived xenograft models in cancer therapy: technologies and applications

Patient-derived xenograft (PDX) models, in which tumor tissues from patients are implanted into immunocompromised or humanized mice, have shown superiority in recapitulating the characteristics of cancer, such as the spatial structure of cancer and the intratumor heterogeneity of cancer. Moreover, PDX models retain the genomic features of patients across different stages, subtypes, and diversified treatment backgrounds. Optimized PDX engraftment procedures and modern technologies such as multi-omics and deep learning have enabled a more comprehensive depiction of the PDX molecular landscape and boosted the utilization of PDX models. These irreplaceable advantages make PDX models an ideal choice in cancer treatment studies, such as preclinical trials of novel drugs, validating novel drug combinations, screening drug-sensitive patients, and exploring drug resistance mechanisms. In this review, we gave an overview of the history of PDX models and the process of PDX model establishment. Subsequently, the review presents the strengths and weaknesses of PDX models and highlights the integration of novel technologies in PDX model research. Finally, we delineated the broad application of PDX models in chemotherapy, targeted therapy, immunotherapy, and other novel therapies.

Inhibition of multiple CDKs potentiates colon cancer chemotherapy via p73-mediated DR5 induction

Targeting cyclin-dependent kinases (CDKs) has recently emerged as a promising therapeutic approach against cancer. However, the anticancer mechanisms of different CDK inhibitors (CDKIs) are not well understood. Our recent study revealed that selective CDK4/6 inhibitors sensitize colorectal cancer (CRC) cells to therapy-induced apoptosis by inducing Death Receptor 5 (DR5) via the p53 family member p73. In this study, we investigated if this pathway is involved in anticancer effects of different CDKIs. We found that less-selective CDKIs, including flavopiridol, roscovitine, dinaciclib, and SNS-032, induced DR5 via p73-mediated transcriptional activation. The induction of DR5 by these CDKIs was mediated by dephosphorylation of p73 at Threonine 86 and p73 nuclear translocation. Knockdown of a common target of these CDKIs, including CDK1, 2, or 9, recapitulated p73-mediated DR5 induction. CDKIs strongly synergized with 5-fluorouracil (5-FU), the most commonly used CRC chemotherapy agent, in vitro and in vivo to promote growth suppression and apoptosis, which required DR5 and p73. Together, these findings indicate p73-mediated DR5 induction as a potential tumor suppressive mechanism and a critical target engaged by different CDKIs in potentiating therapy-induced apoptosis in CRC cells. These findings help better understand the anticancer mechanisms of CDKIs and may help facilitate their clinical development and applications in CRC.

Brd4 proteolysis-targeting chimera nanoparticles sensitized colorectal cancer chemotherapy

Bromodomain-Containing Protein 4 (BRD4) is a member of the BET family of bromodomains, which participates in gene transcription process and is closely related to tumor progression. We observed the up-regulated expression of BRD4 in colorectal cancer (CRC) after doxorubicin (DOX) treatment, which might be a potential mechanism for DOX resistance. This study constructed the tumor-targeting (cyclo (Arg-Gly-Asp-D-Phe-Lys)-poly(ethylene glycol)-poly(ε-caprolactone)) (cRGD-PEG-PCL) copolymer for co-delivery of DOX and BRD4 PROTAC degrader ARV-825 (ARV-DOX/cRGD-P) for CRC treatment. The ARV-DOX/cRGD-P complexes elicited synergistic anti-tumor effect via cell cycle arrest and the increased cell apoptosis, and mechanism studies implicated the regulation of proliferation- and apoptosis-related pathways in vitro. Moreover, the administration of ARV-DOX/cRGD-P significantly improved anti-tumor activity in subcutaneous colorectal tumors and colorectal intraperitoneal disseminated tumor models in mice by promoting tumor apoptosis, suppressing tumor proliferation and angiogenesis. Taken together, these data reveal that ARV-825 can heighten DOX sensitivity in CRC treatment and BRD4 is a potential therapeutic target for DOX-resistant CRC. The ARV-DOX/cRGD-P preparations have outstanding anti-cancer effects and may be used for clinical treatment of colorectal cancer in the future.

Synthetical lethality of Werner helicase and mismatch repair deficiency is mediated by p53 and PUMA in colon cancer

Synthetic lethality is a powerful approach for targeting oncogenic drivers in cancer. Recent studies revealed that cancer cells with microsatellite instability (MSI) require Werner (WRN) helicase for survival; however, the underlying mechanism remains unclear. In this study, we found that WRN depletion strongly induced p53 and its downstream apoptotic target PUMA in MSI colorectal cancer (CRC) cells. p53 or PUMA deletion abolished apoptosis induced by WRN depletion in MSI CRC cells. Importantly, correction of MSI abrogated the activation of p53/PUMA and cell killing, while induction of MSI led to sensitivity in isogenic CRC cells. Rare p53-mutant MSI CRC cells are resistant to WRN depletion due to lack of PUMA induction, which could be restored by wildtype (WT) p53 knock in or reconstitution. WRN depletion or treatment with the RecQ helicase inhibitor ML216 suppressed in vitro and in vivo growth of MSI CRCs in a p53/PUMA-dependent manner. ML216 treatment was efficacious in MSI CRC patient-derived xenografts. Interestingly, p53 gene remains WT in the majority of MSI CRCs. These results indicate a critical role of p53/PUMA-mediated apoptosis in the vulnerability of MSI CRCs to WRN loss, and support WRN as a promising therapeutic target in p53-WT MSI CRCs.

Regulation of programmed cell death by Brd4

Epigenetic factor Brd4 has emerged as a key regulator of cancer cell proliferation. Targeted inhibition of Brd4 suppresses growth and induces apoptosis of various cancer cells. In addition to apoptosis, Brd4 has also been shown to regulate several other forms of programmed cell death (PCD), including autophagy, necroptosis, pyroptosis, and ferroptosis, with different biological outcomes. PCD plays key roles in development and tissue homeostasis by eliminating unnecessary or detrimental cells. Dysregulation of PCD is associated with various human diseases, including cancer, neurodegenerative and infectious diseases. In this review, we discussed some recent findings on how Brd4 actively regulates different forms of PCD and the therapeutic potentials of targeting Brd4 in PCD-related human diseases. A better understanding of PCD regulation would provide not only new insights into pathophysiological functions of PCD but also provide new avenues for therapy by targeting Brd4-regulated PCD.

Dual inhibition of BET and HAT/p300 suppresses colorectal cancer via DR5- and p53/PUMA-mediated cell death

Background

Colorectal cancer (CRC) frequently has a dysregulated epigenome causing aberrant up-regulation of oncogenes such as c-MYC. Bromodomain and extra-terminal domain (BET) proteins and histone acetyltransferases (HAT) are epigenetic regulatory proteins that create and maintain epigenetic states supporting oncogenesis. BET inhibitors and HAT inhibitors are currently being investigated as cancer therapeutics due to their ability to suppress cancer-promoting epigenetic modifiers. Due to the extensive molecular crosstalk between BET proteins and HAT proteins, we hypothesized that dual inhibition of BET and HAT could more potently inhibit CRC cells than inhibition of each individual protein.

Methods

We investigated the activity and mechanisms of a dual BET and HAT inhibitor, NEO2734, in CRC cell lines and mouse xenografts. MTS, flow cytometry, and microscopy were used to assess cell viability. qPCR, Western blotting, and immunofluorescent staining were used to assess mechanisms of action.

Results

We found that NEO2734 more potently suppresses CRC cell growth than first generation BET inhibitors, regardless of the status of common CRC driver mutations. We previously showed that BET inhibitors upregulate DR5 to induce extrinsic apoptosis. In the current study, we show that NEO2734 treatment induces CRC cell apoptosis via both the intrinsic and extrinsic apoptosis pathways. NEO2734 increases p53 expression and subsequently increased expression of the p53-upregulated mediator of apoptosis (PUMA), which is a critical mechanism for activating intrinsic apoptosis. We demonstrate that inhibition of either the intrinsic or extrinsic branches of apoptosis partially rescues CRC cells from NEO2734 treatment, while the dual inhibition of both branches of apoptosis more strongly rescues CRC cells from NEO2734 treatment. Finally, we show that NEO2734 monotherapy is able to suppress tumor growth in CRC xenografts by inducing apoptosis.

Conclusions

Our study demonstrates NEO2734 potently suppresses CRC cells in vitro and in vivo by simultaneously upregulating PUMA and DR5 to induce cell death. Further studies of NEO2734 for treating CRC are warranted.

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.

Epigenetic regulation of autophagy in gastrointestinal cancers

The development of novel therapeutic approaches is necessary to manage gastrointestinal cancers (GICs). Considering the effective molecular mechanisms involved in tumor growth, the therapeutic response is pivotal in this process. Autophagy is a highly conserved catabolic process that acts as a double-edged sword in tumorigenesis and tumor inhibition in a context-dependent manner. Depending on the stage of malignancy and cellular origin of the tumor, autophagy might result in cancer cell survival or death during the GICs' progression. Moreover, autophagy can prevent the progression of GIC in the early stages but leads to chemoresistance in advanced stages. Therefore, targeting specific arms of autophagy could be a promising strategy in the prevention of chemoresistance and treatment of GIC. It has been revealed that autophagy is a cytoplasmic event that is subject to transcriptional and epigenetic regulation inside the nucleus. The effect of epigenetic regulation (including DNA methylation, histone modification, and expression of non-coding RNAs (ncRNAs) in cellular fate is still not completely understood. Recent findings have indicated that epigenetic alterations can modify several genes and modulators, eventually leading to inhibition or promotion of autophagy in different cancer stages, and mediating chemoresistance or chemosensitivity. The current review focuses on the links between autophagy and epigenetics in GICs and discusses: 1) How autophagy and epigenetics are linked in GICs, by considering different epigenetic mechanisms; 2) how epigenetics may be involved in the alteration of cancer-related phenotypes, including cell proliferation, invasion, and migration; and 3) how epidrugs modulate autophagy in GICs to overcome chemoresistance.

Targeting Myc-driven stress vulnerability in mutant KRAS colorectal cancer

Mutant KRAS is a key driver in colorectal cancer (CRC) and promotes Myc translation and Myc-dependent stress adaptation and proliferation. Here, we report that the combination of two FDA-approved drugs Bortezomib and Everolimus (RAD001) (BR) is highly efficacious against mutant KRAS CRC cells. Mechanistically, the combination, not single agent, rapidly depletes Myc protein, not mRNA, and leads to GCN2- and p-eIF2α-dependent cell death through the activation of extrinsic and intrinsic apoptotic pathways. Cell death is selectively induced in mutant KRAS CRC cells with elevated basal Myc and p-eIF2α and is characterized by CHOP induction and transcriptional signatures in proteotoxicity, oxidative stress, metabolic inhibition, and immune activation. BR-induced p-GCN2/p-eIF2α elevation and cell death are strongly attenuated by MYC knockdown and enhanced by MYC overexpression. The BR combination is efficacious against mutant KRAS patient derived organoids (PDO) and xenografts (PDX) by inducing p-eIF2α/CHOP and cell death. Interestingly, an elevated four-gene (DDIT3, GADD45B, CRYBA4 and HSPA1L) stress signature is linked to shortened overall survival in CRC patients. These data support that Myc-dependent stress adaptation drives the progression of mutant KRAS CRC and serves as a therapeutic vulnerability, which can be targeted using dual translational inhibitors.

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 (ICD) 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 TNF-related apoptosis-inducing ligand (TRAIL), 5-fluorouracil (5-FU) 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.

Epigenetic Approaches to Overcome Fluoropyrimidines Resistance in Solid Tumors

Simple Summary

Fluoropyrimidines represent the backbone of many combination chemotherapy regimens for the treatment of solid cancers but are still associated with toxicity and mechanisms of resistance. In this review, we focused on the epigenetic modifiers histone deacetylase inhibitors (HDACis) and on their ability to regulate specific genes and proteins involved in the fluoropyrimidine metabolism and resistance mechanisms. We presented emerging preclinical and clinical studies, highlighting the mechanisms by which HDACis can prevent/overcome the resistance and/or enhance the therapeutic efficacy of fluoropyrimidines, potentially reducing their toxicity, and ultimately improving the overall survival of cancer patients.

Abstract

Although fluoropyrimidines were introduced as anticancer agents over 60 years ago, they are still the backbone of many combination chemotherapy regimens for the treatment of solid cancers. Like other chemotherapeutic agents, the therapeutic efficacy of fluoropyrimidines can be affected by drug resistance and severe toxicities; thus, novel therapeutic approaches are required to potentiate their efficacy and overcome drug resistance. In the last 20 years, the deregulation of epigenetic mechanisms has been shown to contribute to cancer hallmarks. Histone modifications play an important role in directing the transcriptional machinery and therefore represent interesting druggable targets. In this review, we focused on histone deacetylase inhibitors (HDACis) that can increase antitumor efficacy and overcome resistance to fluoropyrimidines by targeting specific genes or proteins. Our preclinical data showed a strong synergistic interaction between HDACi and fluoropyrimidines in different cancer models, but the clinical studies did not seem to confirm these observations. Most likely, the introduction of increasingly complex preclinical models, both in vitro and in vivo, cannot recapitulate human complexity; however, our analysis of clinical studies revealed that most of them were designed without a mechanistic approach and, importantly, without careful patient selection.

Bromodomain and extra-terminal inhibitors emerge as potential therapeutic avenues for gastrointestinal cancers

Gastrointestinal (GI) cancers, including colorectal cancer, pancreatic cancer, liver cancer and gastric cancer, are severe social burdens due to high incidence and mortality rates. Bromodomain and extra-terminal (BET) proteins are epigenetic readers consisting of four conserved members (BRD2, BRD3, BRD4 and BRDT). BET family perform pivotal roles in tumorigenesis through transcriptional regulation, thereby emerging as potential therapeutic targets. BET inhibitors, disrupting the interaction between BET proteins and acetylated lysines, have been reported to suppress tumor initiation and progression in most of GI cancers. In this review, we will demonstrate how BET proteins participate in the GI cancers progression and highlight the therapeutic potential of targeting BET proteins for GI cancers treatment.

BET protein degradation triggers DR5-mediated immunogenic cell death to suppress colorectal cancer and potentiate immune checkpoint blockade

Bromodomain and extra-terminal domain (BET) family proteins are epigenetic readers that play a critical role in oncogenesis by controlling the expression of oncogenes such as c-Myc. Targeting BET family proteins has recently emerged as a promising anticancer strategy. However, the molecular mechanisms by which cancer cells respond to BET inhibition are not well understood. In this study, we found that inducing the degradation of BET proteins by the proteolysis targeting chimeras (PROTAC) approach potently suppressed the growth of colorectal cancer (CRC) including patient-derived tumors. Mechanistically, BET degradation transcriptionally activates Death Receptor 5 (DR5) to trigger immunogenic cell death (ICD) in CRC cells. Enhanced DR5 induction further sensitizes CRC cells with a mutation in Speckle-type POZ protein (SPOP). Furthermore, DR5 is indispensable for a striking antitumor effect of combining BET degradation and anti-PD-1 antibody, which was well tolerated in mice and almost eradicated syngeneic tumors. Our results demonstrate that BET degradation triggers DR5-mediated ICD to potently suppress CRC and potentiate immune checkpoint blockade. These results provide a rationale, mechanistic insights, and potential biomarkers for developing a precision CRC therapy by inducing BET protein degradation.

Identification of a Novel Immune-Related CpG Methylation Signature to Predict Prognosis in Stage II/III Colorectal Cancer

With the increasing incidence of colorectal cancer (CRC) and continued difficulty in treating it using immunotherapy, there is an urgent need to identify an effective immune-related biomarker associated with the survival and prognosis of patients with this disease. DNA methylation plays an essential role in maintaining cellular function, and changes in methylation patterns may contribute to the development of autoimmunity, aging, and cancer. In this study, we aimed to identify a novel immune-related methylated signature to aid in predicting the prognosis of patients with CRC. We investigated DNA methylation patterns in patients with stage II/III CRC using datasets from The cancer genome atlas (TCGA). Overall, 182 patients were randomly divided into training (n = 127) and test groups (n = 55). In the training group, five immune-related methylated CG sites (cg11621464, cg13565656, cg18976437, cg20505223, and cg20528583) were identified, and CG site-based risk scores were calculated using univariate Cox proportional hazards regression in patients with stage II/III CRC. Multivariate Cox regression analysis indicated that methylated signature was independent of other clinical parameters. The Kaplan-Meier analysis results showed that CG site-based risk scores could significantly help distinguish between high- and low-risk patients in both the training (P = 0.000296) and test groups (P = 0.022). The area under the receiver operating characteristic curve in the training and test groups were estimated to be 0.771 and 0.724, respectively, for prognosis prediction. Finally, stratified analysis results suggested the remarkable prognostic value of CG site-based risk scores in CRC subtypes. We identified five methylated CG sites that could be used as an efficient overall survival (OS)-related biomarker for stage II/III CRC patients.

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 APC^Min/+ 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.

Inhibition of EZH2 enhances the therapeutic effect of 5-FU via PUMA upregulation in colorectal cancer

Although the survival rate of patients with cancer have increased due to the use of current chemotherapeutic agents, adverse effects of cancer therapy remain a concern. The reversal of drug resistance, reduction in harmful side effects and accelerated increase in efficiency have often been addressed in the development of combination therapeutics. Tazemetostat (EPZ-6438), a histone methyltransferase EZH2 selective inhibitor, was approved by the FDA for the treatment of advanced epithelioid sarcoma. However, the effect of tazemetostat on colorectal cancer (CRC) and 5-FU sensitivity remains unclear. In this study, the enhancement of tazemetostat on 5-FU sensitivity was examined in CRC cells. Our findings demonstrated that tazemetostat combined with 5-FU exhibits synergistic antitumor function in vitro and in vivo in CRC cells. In addition, tazemetostat promotes PUMA induction through the ROS/ER stress/CHOP axis. PUMA depletion attenuates the antitumor effect of the combination therapy. Therefore, tazemetostat may be a novel treatment to improve the sensitivity of tumors to 5-FU in CRC therapy. In conclusion, the combination of 5-FU and tazemetostat shows high therapeutic possibility with reduced unfavorable effects.

eIF4E S209 phosphorylation licenses myc- and stress-driven oncogenesis

To better understand a role of eIF4E S209 in oncogenic translation, we generated EIF4E^S209A/+ heterozygous knockin (4EKI) HCT 116 human colorectal cancer (CRC) cells. 4EKI had little impact on total eIF4E levels, cap binding or global translation, but markedly reduced HCT 116 cell growth in spheroids and mice, and CRC organoid growth. 4EKI strongly inhibited Myc and ATF4 translation, the integrated stress response (ISR)-dependent glutamine metabolic signature, AKT activation and proliferation in vivo. 4EKI inhibited polyposis in Apc^Min/+ mice by suppressing Myc protein and AKT activation. Furthermore, p-eIF4E was highly elevated in CRC precursor lesions in mouse and human. p-eIF4E cooperated with mutant KRAS to promote Myc and ISR-dependent glutamine addiction in various CRC cell lines, characterized by increased cell death, transcriptomic heterogeneity and immune suppression upon deprivation. These findings demonstrate a critical role of eIF4E S209-dependent translation in Myc and stress-driven oncogenesis and as a potential therapeutic vulnerability.

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.

P2X7R promotes angiogenesis and tumour-associated macrophage recruitment by regulating the NF-κB signalling pathway in colorectal cancer cells

Overexpression of P2X7R has been observed in several tumours and is related to cancer advancement and metastasis. However, the role of P2X7R in colorectal cancer (CRC) patients is not well understood. In the current study, overexpression of P2X7R and the effects at the molecular and functional levels in CRC were assessed in a mouse orthotopic model. Functional assays, such as the CCK‐8 assay, wound healing and transwell assay, were used to determine the biological role of P2X7R in CRC cells. CSC‐related genes and properties were detected via sphere formation and real‐time PCR assays. The underlying mechanisms were explored by Western blotting, real‐time PCR and Flow cytometry. In this study, we found that overexpression of P2X7R increases in the in vivo growth of tumours. P2X7R overexpression also increased CD31, VEGF and concurrent angiogenesis. P2X7R up‐regulates aldehyde dehydrogenase‐1 (ALDH1) and CSC characteristics. Transplanted tumour cells with P2X7R overexpression stimulated cytokines to recruit tumour‐associated macrophage (TAMs) to increase the growth of tumours. We also found that the NF‐κB signalling pathway is involved in P2X7R‐induced cytokine up‐regulation. P2X7R promotes NF‐κB–dependent cytokine induction, which leads to TAM recruitment to control tumour growth and advancement and remodelling of the stroma. Our findings demonstrate that P2X7R plays a key role in TAM recruitment, which may be a therapeutic target for CRC patients.

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.

Blocking the Bromodomains Function Contributes to Disturbances in Alga Chara vulgaris Spermatids Differentiation

Bromodomain containing (BRD) proteins play an essential role in many cellular processes. The aim of this study was to estimate activity of bromodomains during alga Chara vulgaris spermatids differentiation. The effect of a bromodomain inhibitor, JQ1 (100 μM), on the distribution of individual stages of spermatids and their ultrastructure was studied. The material was Feulgen stained and analysed in an electron microscope. JQ1 caused shortening of the early stages of spermiogenesis and a reverse reaction at the later stages. Additionally, in the same antheridium, spermatids at distant developmental stages were present. On the ultrastructural level, chromatin fibril system disorders and significantly distended endoplasmic reticulum (ER) cisternae already at the early stages were observed. Many autolytic vacuoles were also visible. The ultrastructural disturbances intensified after prolonged treatment with JQ1. The obtained data show that JQ1 treatment led to changes in the spermatid number and disturbances in chromatin condensation and to cytoplasm reduction. The current studies show some similarities between C. vulgaris and mammals spermiogenesis. Taken together, these results suggest that JQ1 interferes with the spermatid differentiation on many interdependent levels and seems to induce ER stress, which leads to spermatid degeneration. Studies on the role of bromodomains in algae spermiogenesis have not been conducted so far.

Development and validation of a novel epigenetic signature for predicting prognosis in colon cancer

Epigenetic factors play a critical role in carcinogenesis by imparting a distinct feature to the chromatin architecture. The present study aimed to develop a novel epigenetic signature for evaluating the relapse-free survival of colon cancer patients. Public microarray datasets were acquired from the Gene Expression Omnibus databases: GSE39582, GSE17538, GSE33113, and GSE37892 set. Patients from GSE39582 set were randomized 1:1 into training and internal validation series. Patients were divided into high-risk and low-risk groups in training series based on a set of 11 epigenetic factors (p < .001). The good reproducibility for the prognostic value of the epigenetic signature was confirmed in the internal validation series (p < .001), external validation series (a combination of GSE17538 set, GSE33113 set, and GSE37892 set; p = .018), and entire series (p < .001). Furthermore, a nomogram, which integrated the epigenetic signature, pathological stage, and postoperative chemotherapy, was developed based on the GSE39582 set. The time-dependent receiver operating characteristic curve at 1 year demonstrated that the comprehensive signature presented superior prognostic value than the pathological stage. In conclusion, an epigenetic signature, which could be utilized to divide colon cancer patients into two groups with significantly different risk of relapse, was established. This biomarker would aid in identifying patients who require an intensive follow-up and aggressive therapeutic intervention.

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.

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-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.

BRD4 Levels Determine the Response of Human Lung Cancer Cells to BET Degraders That Potently Induce Apoptosis through Suppression of Mcl-1

Lung cancer consists of approximately 80% non-small cell lung cancer (NSCLC) and 20% small cell lung cancer (SCLC) and remains the leading cause of cancer-related deaths worldwide despite advances in early diagnosis, targeted therapy, and immunotherapy. Thus, novel therapies are still urgently needed. Bromodomain and extraterminal (BET) proteins, primarily comprised of BRD2, BRD3, and BRD4 proteins, function as epigenetic readers and master transcription coactivators and are now recognized cancer therapeutic targets. BET degraders such as ZBC260 and dBET represent a novel class of BET inhibitors that act by inducing BET degradation. The current study demonstrates the therapeutic efficacies of BET degraders, particularly ZBC260, against lung cancer, as well as understanding the underlying mechanisms and identifying molecular markers that determine cell sensitivity to BET degraders. A panel of NSCLC cell lines possessed similar response patterns to ZBC260 and dBET but different responses to BET inhibitor JQ-1. BRD levels, particularly BRD4, correlated positively with high sensitivity to BET degraders but not to JQ-1. BET degraders potently induced apoptosis in sensitive NSCLC cells and were accompanied by reduction of Mcl-1 and c-FLIP levels, which are critical for mediating induction of apoptosis and enhancement of TRAIL-induced apoptosis. Accordingly, ZBC260 exerted more potent activity than JQ-1 in vivo against the growth of NSCLC xenografts and patient-derived xenografts. These findings warrant future clinical validation of the efficacy of BET degraders in NSCLC, particularly those with high levels of BRD proteins, especially BRD4. SIGNIFICANCE: The current study demonstrates the potential of novel BET degraders in the treatment of lung cancer and warrants clinical validation of BET degraders in lung cancer with high levels of BRD4.

Bromodomain and extraterminal domain inhibitor enhances the antitumor effect of imatinib in gastrointestinal stromal tumours

In gastrointestinal stromal tumours (GISTs), the function of bromodomain-containing 4 (BRD4) remains underexplored. BRD4 mRNA abundance was quantified in GISTs. In the current study, we investigated the role of BRD4 in GISTs. Our results show a significant enhancement in BRD4 mRNA and a shift from very low-risk/low-risk to high-risk levels as per NCCN specifications. Overexpression of BRD4 correlated with unfavourable genotype, nongastric location, enhanced risk and decreased disease-free survival, which were predicted independently. Knockout of BRD4 in vitro suppressed KIT expression, which led to inactivation of the KIT/PI3K/AKT/mTOR pathway, impeded migration and cell growth and made the resistant GIST cells sensitive to imatinib. The expression of KIT was repressed by a BRD4 inhibitor JQ1, which also induced myristoylated-AKT-suppressible caspases 3 and 9 activities, induced LC3-II, exhibited dose-dependent therapeutic synergy with imatinib and attenuated the activation of the PI3K/AKT/mTOR pathway. In comparison with their single therapy, the combination of JQ1/imatinib more efficiently suppressed the growth of xenografts and exhibited a reduction in KIT phosphorylation, a decrease in Ki-67 and in the levels of phosphorylated PI3K/AKT/mTOR and enhanced TUNEL staining. Thus, we characterized the biological, prognostic and therapeutic implications of overexpressed BRD4 in GIST and observed that JQ1 suppresses KIT transactivation and nullifies the activation of PI3K/AKT/mTOR, providing a potential strategy for treating imatinib-resistant GIST through dual blockade of KIT and BRD4.

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.

High Loading of Hydrophobic and Hydrophilic Agents via Small Immunostimulatory Carrier for Enhanced Tumor Penetration and Combinational Therapy

Development of small-sized nanoformulations for effective tumor penetration, particularly for those tumors with dense stroma is a major challenge in cancer nanomedicine. It is even more challenging to achieve effective co-loading of both hydrophobic and hydrophilic anticancer agents through a small-sized nanocarrier. In this work, we designed a novel redox-responsive gemcitabine (GEM)-conjugated polymer POEG-co-PVDGEM (PGEM) as a small-sized nanocarrier to co-deliver hydrophilic GEM and hydrophobic paclitaxel (PTX). Methods: The in vitro physicochemical and biological properties of PTX/PGEM NPs were characterized. The efficiency of the PGEM carrier in selective codelivery of GEM and PTX in two murine tumor models as well as a patient derived xenograft model (PDX) was also evaluated. In addition, we investigated the changes in tumor immune microenvironment after treatment with PTX/PGEM nanoparticles. Results: We discovered that GEM conjugation could significantly decrease the nanoparticle size from 160 nm to 13 nm. Moreover, different from most reported GEM-conjugated polymers, PGEM polymer could serve as a prodrug carrier to load a wide variety of hydrophobic agents with high drug loading capacity and excellent stability. More importantly, our strategy could be extended to various nucleotides-based drugs such as azacytidine, decitabine and cytarabine, suggesting a new platform for co-delivery of various first line hydrophilic and hydrophobic anticancer agents. Imaging showed that our small-sized carrier was much more effective in tumor accumulation and penetration compared to the relatively large-sized drug carrier. The PGEM prodrug-based carrier not only well retained the pharmacological activity of GEM, but also boosted T-cell immune response. Furthermore, delivery of PTX via PGEM led to significantly improved antitumor activity in several murine cancer models and a PDX model of colon cancer. Conclusion: This work not only provided a small-sized carrier platform that was able to load multiple hydrophilic and hydrophobic drugs with high loading capacity, but also provided an effective regimen for enhanced tumor penetration and improved anti-tumor immunity.

BRD4 promotes tumor progression and NF-κB/CCL2-dependent tumor-associated macrophage recruitment in GIST

The most commonly occurring sarcoma of the soft tissue is gastrointestinal stromal tumor (GIST). Treatment and prevention of the disease necessitate an understanding of the molecular mechanisms involved. However, the role of BRD4 in the progression of GIST is still unclear. While it is known there are abundant infiltrating tumor-associated macrophages (TAMs) in the tumor microenvironment, the exact role of these cells has yet to be studied. This work showed an upregulation of BRD4 in GIST that was associated with GIST prognosis. Through gain and loss of function studies, it was found that BRD4 promotes GIST growth and angiogenesis in vitro and in vivo. Mechanistically, BRD4 enhances CCL2 expression by activating the NF-κB signaling pathway. Furthermore, this CCL2 upregulation causes recruitment of macrophages into the tumor leading to tumor growth. A likely mechanism for interactions in the GIST microenvironment has been outlined by this work to show the role and potential use of BRD4 as a treatment target in GIST.

BET inhibitor bromosporine enhances 5-FU effect in colorectal cancer cells

Treatment of colorectal cancer (CRC) remains a challenge because of the lack of effective early treatment strategies and high incidence of relapse. 5-Fluorouracil (5-FU) is a typical CRC treatment. Bromosporine is an innovative bromodomain and extraterminal domain (BET) inhibitor. We investigated if CRC could be targeted by the combination of 5-FU and bromosporine in a synergistic manner in vivo and in vitro. Our findings shown that the combination treatment inhibits cell viability, formation of colonies, increased apoptosis and cell cycle arrest at G0-G1. In addition, the expression level of BRD4 was high in HCT116 cells exposed to 5-FU that showed lower apoptosis against the parental cells. Moreover, the 5-FU-resistance was reversed significantly by BRD4 knockdown or inhibition. The drug combination showed increased activity against tumor than individual drug exposure in the xenograft model. In conclusion, this work serves as a basic clinical evaluation of 5-FU and bromosporine as an effective therapeutic approach for CRC.