BEZ235 Increases the Sensitivity of Hepatocellular Carcinoma to Sorafenib by Inhibiting PI3K/AKT/mTOR and Inducing Autophagy

Roles of Rictor alterations in gastrointestinal tumors (Review)

Gastrointestinal tumors account for five of the top 10 causes of mortality from all cancers (colorectal, liver, stomach, esophageal and pancreatic cancer). Mammalian target of rapamycin (mTOR) signaling is commonly dysregulated in various human cancers. As a core component of the mTOR complex 2 (mTORC2), Rictor is a key effector molecule of the PI3K/Akt pathway. A high alteration rate of Rictor has been observed in gastrointestinal tumors, and such Rictor alterations are often associated with resistance to chemotherapy and related adverse clinical outcomes. However, the exact roles of Rictor in gastrointestinal tumors remain elusive. The aim of the present study was to critically discuss the following: i) Mutation and biological characteristics of Rictor in tumors with a detailed overview of Rictor in cell proliferation, angiogenesis, apoptosis, autophagy and drug resistance; ii) the role of Rictor in tumors of the digestive system, particularly colorectal, hepatobiliary, gastric, esophageal and pancreatic cancer and cholangiocarcinoma; and iii) the current status and prospects of targeted therapy for Rictor by inhibiting Akt activation. Despite the growing realization of the importance of Rictor/mTORC2 in cancer, the underlying mechanistic details remain poorly understood; this needs to change in order for the development of efficient targeted therapies and re‑sensitization of therapy‑resistant cancers to be made possible.

Nanomedicine for cancer targeted therapy with autophagy regulation

Nanoparticles have unique physical and chemical properties and are currently widely used in disease diagnosis, drug delivery, and new drug development in biomedicine. In recent years, the role of nanomedical technology in cancer treatment has become increasingly obvious. Autophagy is a multi-step degradation process in cells and an important pathway for material and energy recovery. It is closely related to the occurrence and development of cancer. Because nanomaterials are highly targeted and biosafe, they can be used as carriers to deliver autophagy regulators; in addition to their favorable physicochemical properties, nanomaterials can be employed to carry autophagy inhibitors, reducing the breakdown of chemotherapy drugs by cancer cells and thereby enhancing the drug's efficacy. Furthermore, certain nanomaterials can induce autophagy, triggering oxidative stress-mediated autophagy enhancement and cell apoptosis, thus constraining the progression of cancer cells.There are various types of nanoparticles, including liposomes, micelles, polymers, metal-based materials, and carbon-based materials. The majority of clinically applicable drugs are liposomes, though other materials are currently undergoing continuous optimization. This review begins with the roles of autophagy in tumor treatment, and then focuses on the application of nanomaterials with autophagy-regulating functions in tumor treatment.

Ezetimibe Induces Paraptosis through Niemann-Pick C1-like 1 Inhibition of Mammalian-Target-of-Rapamycin Signaling in Hepatocellular Carcinoma Cells

Currently, hepatocellular carcinoma (HCC) is characterized by its unfavorable prognosis and resistance to conventional chemotherapy and radiotherapy. Drug repositioning, an approach aimed at identifying novel therapeutic applications for existing drugs, presents a cost-effective strategy for developing new anticancer agents. We explored the anticancer properties of Ezetimibe, a widely used oral lipid-lowering drug, in the context of HCC. Our findings demonstrate that Ezetimibe effectively suppresses HCC cell proliferation through paraptosis, an apoptotic-independent cell death pathway. The examination of HCC cells lines treated with Ezetimibe using light microscopy and transmission electron microscopy (TEM) showed cytoplasmic vacuolation in the perinuclear region. Notably, the nuclear membrane remained intact in both Ezetimibe-treated and untreated HCC cell lines. Probe staining assays confirmed that the cytoplasmic vacuoles originated from dilated endoplasmic reticulum (ER) compartments rather than mitochondria. Furthermore, a dose-dependent accumulation of reactive oxygen species (ROS) was observed in Ezetimibe-treated HCC cell lines. Co-treatment with the general antioxidant NAC attenuated vacuolation and improved cell viability in Ezetimibe-treated HCC cells. Moreover, Ezetimibe induced paraptosis through proteasome activity inhibition and initiation of the unfolded protein response (UPR) in HCC cell lines. In our in vivo experiment, Ezetimibe significantly impeded the growth of HCC tumors. Furthermore, when combined with Sorafenib, Ezetimibe exhibited a synergistic antitumor effect on HCC cell lines. Mechanistically, Ezetimibe induced paraptosis by targeting NPC1L1 to inhibit the PI3K/AKT/mTOR signaling pathway. In conclusion, our study highlights the potential of Ezetimibe as an anticancer agent by triggering paraptosis in HCC cells.

Dual blockade of EGFR and PI3K signaling pathways offers a therapeutic strategy for glioblastoma

BACKGROUND

Glioblastoma multiforme (GBM) is a devastating disease that lacks effective drugs for targeted therapy. Previously, we found that the third-generation epidermal growth factor receptor (EGFR) inhibitor AZD-9291 persistently blocked the activation of the ERK pathway but had no inhibitory effect on the phosphoinositide 3-kinase (PI3K)/Akt pathway. Given that the PI3K inhibitor GDC-0084 is being evaluated in phase I/II clinical trials of GBM treatment, we hypothesized that combined inhibition of the EGFR/ERK and PI3K/Akt pathways may have a synergistic effect in the treatment of GBM.

METHODS

The synergistic effects of cotreatment with AZD-9291 and GDC-0084 were validated using cell viability assays in GBM and primary GBM cell lines. Moreover, the underlying inhibitory mechanisms were assessed through colony formation, EdU proliferation, and cell cycle assays, as well as RNA-seq analyses and western blot. The therapeutic effects of the drug combination on tumor growth and survival were investigated in mice bearing tumors using subcutaneously or intracranially injected LN229 xenografts.

RESULTS

Combined treatment with AZD-9291 and GDC-0084 synergistically inhibited the proliferation and clonogenic survival, as well as induced cell cycle arrest of GBM cells and primary GBM cells, compared to monotherapy. Moreover, AZD-9291 plus GDC-0084 combination therapy significantly inhibited the growth of subcutaneous tumors and orthotopic brain tumor xenografts, thus prolonging the survival of tumor-bearing mice. More importantly, the combination of AZD-9291 and GDC-0084 simultaneously blocked the activation of the EGFR/MEK/ERK and PI3K/AKT/mTOR signaling pathways, thereby exerting significant antitumor activity.

CONCLUSION

Our findings demonstrate that the combined blockade of the EGFR/MEK/ERK and PI3K/AKT/mTOR pathways is more effective against GBM than inhibition of each pathway alone, both in vitro and in vivo. Our results suggest that AZD-9291 combined with GDC-0084 may be considered as a potential treatment strategy in future clinical trials. Video Abstract.

The stage-dependent prognostic role of ARID1A in hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is one of the most common causes of cancer-related death. Although novel treatment currently achieves a better response, the majority of HCC patients develop resistance and cannot benefit. Hence, novel biomarkers for guiding therapy and predicting the prognosis are needed.

Methods

Tissue microarrays of 206 HCC patients were used, and ARID1A expression was determined by immunohistochemistry. Databases were used for the verification and expansion of our results. The "rms" package of R software was used for the construction of the nomogram.

Results

ARID family alterations were associated with disease-free survival (P=0.0325) and overall survival (OS) (P=0.0076). Subgroup analysis confirmed the prognostic effect of ARID1A, ARID1B, and ARID2 alterations. In addition, ARID family genomic alterations, especially ARID1A, were closely related to poor progression-free survival (ARID: P=0.0011; ARID1A: P=0.0082) and OS (ARID: P=0.0161; ARID1A: P=0.0220) after sorafenib treatment. ARID1A expression was found to display a stage-dependent effect on the prognosis, serving as a risk factor in stage I-II patients (P<0.0001) and a protective factor in stage III-IV patients (P=0.0180).

Conclusions

ARID1A has dual roles in HCC in a tumor stage-dependent manner, and further study is required to uncover the complex function of ARID1A in HCC development, disease progression, and therapy.

Chitosan nanoparticles encapsulated with BEZ235 prevent acute rejection in mouse heart transplantation

Acute rejection may manifest following heart transplantation, despite the implementation of relatively well-established immunosuppression protocols. The significance of the mTOR signaling pathway in rejection is widely acknowledged. BEZ235, a second-generation mTOR inhibitor with dual inhibitory effects on PI3K and mTOR, holds promise for clinical applications. This study developed a nanodelivery system, BEZ235@NP, to facilitate the intracellular delivery of BEZ235, which enhances efficacy and reduces adverse effects by improving the poor solubility of BEZ235. In the complete MHCII-mismatched model, BEZ235@NP significantly prolonged cardiac allografts survival compared to free BEZ235, which was attributed to more effective suppression of effector T cell activation and promotion of greater expansion of Tregs. These nanoparticles demonstrated excellent biosafety and exhibited no short-term biotoxicity upon investigation. To elucidate the mechanism, primary T cells were isolated from the spleen and it was observed that BEZ235@NP treatment resulted in the arrest of these cells in the G0/G1 phase. As indicated by Western blot analysis, BEZ235@NP substantially reduced mTOR phosphorylation. This, in turn, suppressed downstream pathways and ultimately exerted an anti-proliferative and anti-activating effect on cells. Furthermore, it was observed that inhibition of the mTOR pathway stimulated T-cell autophagy. In conclusion, the strategy of intracellular delivery of BEZ235 presents promising applications for the treatment of acute rejection.

Autophagy-Related Gene WD Repeat Domain 45B Promotes Tumor Proliferation and Migration of Hepatocellular Carcinoma through the Akt/mTOR Signaling Pathway

Hepatocellular carcinoma (HCC) is a highly aggressive malignant tumor. It has been found that autophagy plays a role both as a tumor promoter and inhibitor in HCC carcinogenesis. However, the mechanism behind is still unveiled. This study aims to explore the functions and mechanism of the key autophagy-related proteins, to shed light on novel clinical diagnoses and treatment targets of HCC. Bioinformation analyses were performed by using data from public databases including TCGA, ICGC, and UCSC Xena. The upregulated autophagy-related gene WDR45B was identified and validated in human liver cell line LO2, human HCC cell line HepG2 and Huh-7. Immunohistochemical assay (IHC) was also performed on formalin-fixed paraffin-embedded (FFPE) tissues of 56 HCC patients from our pathology archives. By using qRT-PCR and Western blots we found that high expression of WDR45B influenced the Akt/mTOR signaling pathway. Autophagy marker LC3- II/LC3-I was downregulated, and p62/SQSTM1 was upregulated after knockdown of WDR45B. The effects of WDR45B knockdown on autophagy and Akt/mTOR signaling pathways can be reversed by the autophagy inducer rapamycin. Moreover, proliferation and migration of HCC can be inhibited after the knockdown of WDR45B through the CCK8 assay, wound-healing assay and Transwell cell migration and invasion assay. Therefore, WDR45B may become a novel biomarker for HCC prognosis assessment and potential target for molecular therapy.

Biological impact and therapeutic perspective of targeting PI3K/Akt signaling in hepatocellular carcinoma: Promises and Challenges

Cancer progression results from activation of various signaling networks. Among these, PI3K/Akt signaling contributes to proliferation, invasion, and inhibition of apoptosis. Hepatocellular carcinoma (HCC) is a primary liver cancer with high incidence rate, especially in regions with high prevalence of viral hepatitis infection. Autoimmune disorders, diabetes mellitus, obesity, alcohol consumption, and inflammation can also lead to initiation and development of HCC. The treatment of HCC depends on the identification of oncogenic factors that lead tumor cells to develop resistance to therapy. The present review article focuses on the role of PI3K/Akt signaling in HCC progression. Activation of PI3K/Akt signaling promotes glucose uptake, favors glycolysis and increases tumor cell proliferation. It inhibits both apoptosis and autophagy while promoting HCC cell survival. PI3K/Akt stimulates epithelial-to-mesenchymal transition (EMT) and increases matrix-metalloproteinase (MMP) expression during HCC metastasis. In addition to increasing colony formation capacity and facilitating the spread of tumor cells, PI3K/Akt signaling stimulates angiogenesis. Therefore, silencing PI3K/Akt signaling prevents aggressive HCC cell behavior. Activation of PI3K/Akt signaling can confer drug resistance, particularly to sorafenib, and decreases the radio-sensitivity of HCC cells. Anti-cancer agents, like phytochemicals and small molecules can suppress PI3K/Akt signaling by limiting HCC progression. Being upregulated in tumor tissues and clinical samples, PI3K/Akt can also be used as a biomarker to predict patients' response to therapy.

ETS-1/c-Met drives resistance to sorafenib in hepatocellular carcinoma

BACKGROUND

The purpose of this study was to clarify the molecular regulatory mechanism of c-Met up-regulated expression and elucidate the molecular mechanisms by which c-Met overexpression and activation drive progression and sorafenib resistance in hepatocellular carcinoma (HCC).

METHODS

The resistance index was calculated. Bioinformatic techniques were applied to predict the transcription factors that bind and their binding sites on the c-Met promoter. Chromatin immunoprecipitation assays were implemented to verify the prediction results. To determine the regulatory mechanisms and effects of c-Met on sorafenib resistance in HCC, c-Met expression and activation were down-regulated by siRNA and inhibitor in in vivo and vitro experiments, while a parental cell line (Huh-7) was transfected with the adenovirus that upregulated c-Met expression.

RESULTS

c-Met expression was increased in HCC sorafenib-resistant cells. Functional findings suggested that c-Met overexpression and activation drive HCC tumor progression and sorafenib resistance by promoting cell proliferation, migration, and stopping apoptosis. Molecular mechanism findings demonstrated that the MEK/ERK signaling pathway activated the expression and activity of ETS-1 mediated by p-ERK, which led to its binding to the c-Met gene promoter and upregulation of c-Met transcriptional expression. The activation of the HGF/c-Met pathway drives sorafenib resistance in HCC cells by activating the Ras/Raf/ERK and PI3K/Akt signaling pathways, which regulate biologic processes, including cell proliferation, migration and anti-apoptosis.

CONCLUSION

c-Met overexpression and activation is an essential mechanism of sorafenib resistance in HCC. Combination therapy of sorafenib plus c-Met inhibitor overcame the resistance of sorafenib-targeted therapy for HCC.

The interactions between integrin α5β1 of liver cancer cells and fibronectin of fibroblasts promote tumor growth and angiogenesis

Hepatocellular carcinoma (HCC) progression is closely related to pathological fibrosis, which involves heterotypic intercellular interactions (HIIs) between liver cancer cells and fibroblasts. Here, we studied them in a direct coculture model, and identified fibronectin from fibroblasts and integrin-α₅β₁ from liver cancer cells as the primary responsible molecules utilizing CRISPR/Cas9 gene-editing technology. Coculture led to the formation of 3D multilayer microstructures, and obvious fibronectin remodeling was caused by upregulated integrin-α₅β₁, which greatly promoted cell growth in 3D microstructures. Integrin-α₅ was more sensitive and specific than integrin-β₁ in this process. Subsequent mechanistic exploration revealed the activation of integrin-Src-FAK, AKT and ERK signaling pathways. Importantly, the growth-promoting effect of HIIs was verified in a xenograft tumor model, in which more blood vessels were observed in bigger tumors derived from the coculture group than that derived from monocultured groups. Hence, we conducted triculture by introducing human umbilical vein endothelial cells, which aligned to and differentiated along multilayer microstructures in an integrin-α₅β₁ dependent manner. Furthermore, fibronectin, integrin-α₅, and integrin-β₁ were upregulated in 52 HCC tumors, and fibronectin was related to microvascular invasion. Our findings identify fibronectin, integrin-α₅, and integrin-β₁ as tumor microenvironment-related targets and provide a basis for combination targeted therapeutic strategies for future HCC treatment.

CYP2C8 Suppress Proliferation, Migration, Invasion and Sorafenib Resistance of Hepatocellular Carcinoma via PI3K/Akt/p27kip1 Axis

Background

Cytochrome P450 2C8 (CYP2C8) gene is one of the members of the cytochrome P450 enzymes (CYPs) gene family. The aim of this study was to reveal the function of CYP2C8 in hepatocellular carcinoma (HCC) and its effect on the sorafenib resistance.

Methods

Differential expression analysis in multiple HCC datasets all suggested that CYP2C8 expression was significantly decreased in HCC tissues, compared with para-carcinoma liver tissues. The expression level of CYP2C8 was subsequently compared between HCC tissues and para-carcinoma liver tissues of 70 patients form Guangxi, China, with the result consistent with the above. Survival analysis and ROC analysis indicated that CYP2C8 was equipped with satisfactory diagnostic and prognostic value in HCC. To examine the effect of CYP2C8 on the malignant phenotype of HCC cells, stable transcriptional cell lines with CYP2C8 over-expression were established, and then Cell Counting Kit-8 (CCK8) assay, colony formation assay, cell cycle assay, cell invasion assay and wound healing assay were performed.

Results

The results of aforementioned assays suggested that CYP2C8 over-expression restricted the proliferation, clonality, migration, invasion and cell cycle of HCC cells but had no significant effect on cell apoptosis. The enrichment analysis in terms of sequencing data of HCC cell lines with stable CYP2C8 over-expression suggested that CYP2C8 might be related to PI3K/Akt/p27^Kip1 axis. The inhibition of CYP2C8 over-expression on PI3K/Akt/p27^Kip1 axis was subsequently demonstrated with Western blot assay. In the rescue experiment, it was observed that both P27 inhibitor and PI3K agonist counteracted the repressed malignant phenotype caused by CYP2C8 over-expression, which further demonstrated that CYP2C8 played a role in HCC cells via PI3K/Akt/p27^Kip1 axis.

Discussion

The results demonstrated that CYP2C8 enhances the anticancer activity of sorafenib in vitro assays and in tumor xenograft model, with Ki-67 down-regulation and PI3K/Akt/p27Kip1 axis inhibition. In conclusion, these findings hinted that CYP2C8 restricted malignant phenotype and sorafenib resistance in HCC via PI3K/Akt/p27^kip1 axis.

Autophagy-Related Chemoprotection against Sorafenib in Human Hepatocarcinoma: Role of FOXO3 Upregulation and Modulation by Regorafenib

Early acquisition of sorafenib resistance is responsible for the dismal prognosis of advanced hepatocarcinoma (HCC). Autophagy, a catabolic process involved in liver homeostasis, has been associated with chemosensitivity modulation. Forkhead box O3 (FOXO3) is a transcription factor linked to HCC pathogenesis whose role on autophagy-related sorafenib resistance remains controversial. Here, we unraveled the linkage between autophagy and sorafenib resistance in HCC, focusing on the implication of FOXO3 and its potential modulation by regorafenib. We worked with two HepG2-derived sorafenib-resistant HCC in vitro models (HepG2S1 and HepG2S3) and checked HCC patient data from the UALCAN database. Resistant cells displayed an enhanced basal autophagic flux compared to HepG2, showing higher autophagolysosome content and autophagy markers levels. Pharmacological inhibition of autophagy boosted HepG2S1 and HepG2S3 apoptosis and subG1 cells, but reduced viability, indicating the cytoprotective role of autophagy. HCC samples displayed higher FOXO3 levels, being associated with shorter survival and autophagic genes expression. Consistently, chemoresistant in vitro models showed significant FOXO3 upregulation. FOXO3 knockdown suppressed autophagy and caused resistant cell death, demonstrating that overactivation of such pro-survival autophagy during sorafenib resistance is FOXO3-dependent; a cytoprotective mechanism that the second-line drug regorafenib successfully abolished. Therefore, targeting FOXO3-mediated autophagy could significantly improve the clinical efficacy of sorafenib.

Autophagy up-regulated by MEK/ERK promotes the repair of DNA damage caused by aflatoxin B1

Aflatoxin B1 (AFB1), a kind of mycotoxin, exerts its cytotoxicity by increasing the oxidative damage of target organs, especially the liver. In vivo and in vitro experiments were carried out to elucidate the toxic mechanism of AFB1. The results of MTT, cloning-formation, flow cytometry, immunocytochemistry, Reverse transcription PCR (RT-PCR) and western blot showed that AFB1 activated NOX2 gp91 phox, inhibited proliferation and migration, and blocked cell cycle at G0/G1 period of HHL-5 cells. Autophagy promoted the repair of NOX2-dependent DNA damage. NOX2/gp91 phox mainly activates MEK/ERK pathway and then up-regulates autophagy. In vivo experiments have shown that AFB1 (0.75 mg/kg daily orally, 4 weeks) had no significant changes in the size and shape of the liver in mice. However, these treatments lead to structural abnormalities of hepatocytes and DNA damage. In summary, AFB1 caused intracellular oxidative stress and DNA damage, NOX2/gp91-phox activates the MEK/ERK pathway, and upregulated autophagy to promote the repair of DNA damage. We concluded that by increasing the level of autophagy, the ability of anti-AFB1 toxicity of liver can be increased.