circRNA circMED27 acts as a prognostic factor and mediator to promote lenvatinib resistance of hepatocellular carcinoma

Circ_0007386 Promotes the Progression of Hepatocellular Carcinoma Through the miR-507/ CCNT2 Axis

Background

Circular RNAs (circRNAs) have been shown to play a crucial role in the initiation and development of Hepatocellular carcinoma (HCC). However, the mechanism and function of circ_0007386 in HCC are still unknown.

Methods

Circ_0007386 expression level in HCC tissues, and HCC cell lines was further analyzed by qRT-PCR. Agarose gel electrophoresis and Sanger sequencing were used to figure out the structure of circ_0007386. The involvement of circ_0007386 in HCC development was evaluated by experimental investigations conducted in both laboratory settings (in vitro) and living organisms (in vivo). RNA immunoprecipitation, Western blotting, luciferase reporter assay and fluorescence in situ hybridization (FISH) were applied for finding out the interaction among circ_0007386, miR-507 and CCNT2. To assess the connection between circ_0007386 and lenvatinib resistance, lenvatinib-resistant HCC cell lines were employed.

Results

The expression of circ_0007386 was found to increase in HCC tissues, and it was observed to be associated with a worse prognosis. Overexpression of circ_0007386 stimulated HCC cells proliferation, invasion, migration and the epithelial-mesenchymal transition (EMT) while silencing of circ_0007386 resulted in the opposite effect. Mechanistic investigations revealed that circ_0007386 acted as a competing endogenous RNA of miR-507 to prevent CCNT2 downregulation. Downregulating miR-507 or overexpressing CCNT2 could reverse phenotypic alterations that originated from inhibiting of circ_0007386. Importantly, circ_0007386 determines the resistance of hepatoma cells to lenvatinib treatment.

Conclusion

Circ_0007386 advanced HCC progression and lenvatinib resistance through the miR-507/ CCNT2 axis. Meanwhile, circ_0007386 served as a potential biomarker and therapeutic target in HCC patients.

CircDCAF8 promotes the progression of hepatocellular carcinoma through miR-217/NAP1L1 Axis, and induces angiogenesis and regorafenib resistance via exosome-mediated transfer

BACKGROUND

Circular RNAs (circRNAs), which are a new type of single-stranded circular RNA, have significant involvement in progression of many diseases, including tumors. Currently, multiple circRNAs have been identified in hepatocellular carcinoma (HCC). Our study aims to investigate the function and mechanism of circDCAF8 in HCC.

METHODS

The expression of circDCAF8 (hsa_circ_0014879) in HCC and para-carcinoma tissue samples was determined using quantitative real-time polymerase chain reaction (qRT-PCR). The biological function of circDCAF8 in HCC was confirmed by experiments conducted both in vitro and in vivo. And the relationship between circDCAF8, miR-217 and NAP1L1 was predicted by database and verified using qRT-PCR, RNA-binding protein immunoprecipitation (RIP) and dual-luciferase reporter assays. Exosomes isolated from HCC cells were utilized to assess the connection of exosomal circDCAF8 with HCC angiogenesis and regorafenib resistance.

RESULTS

CircDCAF8 is upregulated in HCC tissues and cell lines, and is linked to an unfavourable prognosis for HCC patients. Functionally, circDCAF8 was proved to facilitate proliferation, migration, invasion and Epithelial-Mesenchymal Transformation (EMT) in HCC cells. Animal examinations also validated the tumor-promoting characteristics of circDCAF8 on HCC. Besides, exosomal circDCAF8 promoted angiogenesis in HUVECs. Mechanistically, circDCAF8 interacted with miR-217 and NAP1L1 was a downstream protein of miR-217. CircDCAF8 promoted NAP1L1 expression by sponging miR-217. In addition, exosomes may transfer circDCAF8 from regorafenib-resistant HCC cells to sensitive cells, where it would confer a resistant phenotype.

CONCLUSION

CircDCAF8 facilitates HCC proliferation and metastasis via the miR-217/NAP1L1 axis. Meanwhile, circDCAF8 can promote angiogenesis and drive resistance to regorafenib, making it a viable therapeutic target for HCC patients.

HDAC Inhibition Sensitize Hepatocellular Carcinoma to Lenvatinib via Suppressing AKT Activation

Hepatocellular carcinoma (HCC) is a deadly malignancy with limited treatment options. As a first-line treatment for advanced HCC, Lenvatinib has been applicated in clinic since 2018. Resistance to Lenvatinib, however, has severely restricted the clinical benefits of this drug. Therefore, it is urgent to explore the potential resistance mechanisms of Lenvatinib and identify appropriate methods to reduce resistance for the treatment of HCC. We identified SAHA, a HDAC inhibitor, to have effective anti-tumor activity against Lenvatinib-resistant HCC organoids by screening a customized drug library. Mechanism analysis revealed that SAHA upregulates PTEN expression and suppresses AKT signaling, which contributes to reversing Lenvatinib resistance in liver cancer cells. Furthermore, combinational application of Lenvatinib and HDAC inhibitor or AKT inhibitor synergistically inhibits HCC cell proliferation and induces cell apoptosis. Finally, we confirmed the synergistic effects of Lenvatinib and SAHA, or AZD5363 in primary liver cancer patient derived organoids. Collectively, these findings may enable the development of Lenvatinib combination therapies for HCC.

Lenvatinib in hepatocellular carcinoma: Resistance mechanisms and strategies for improved efficacy

Hepatocellular carcinoma (HCC), one of the most prevalent and destructive causes of cancer-related deaths worldwide, approximately 70% of patients with HCC exhibit advanced disease at diagnosis, limiting the potential for radical treatment. For such patients, lenvatinib, a long-awaited alternative to sorafenib for first-line targeted therapy, has become a key treatment. Unfortunately, despite some progress, the prognosis for advanced HCC remains poor because of drug resistance development. However, the molecular mechanisms underlying lenvatinib resistance and ways to relief drug resistance in HCC are largely unknown and lack of systematic summary; thus, this review not only aims to explore factors contributing to lenvatinib resistance in HCC, but more importantly, summary potential methods to conquer or mitigate the resistance. The results suggest that abnormal activation of pathways, drug transport, epigenetics, tumour microenvironment, cancer stem cells, regulated cell death, epithelial-mesenchymal transition, and other mechanisms are involved in the development of lenvatinib resistance in HCC and subsequent HCC progression. To improve the therapeutic outcomes of lenvatinib, inhibiting acquired resistance, combined therapies, and nano-delivery carriers may be possible approaches.

Long Non-Coding RNAs as Determinants of Thyroid Cancer Phenotypes: Investigating Differential Gene Expression Patterns and Novel Biomarker Discovery

Thyroid Cancer (TC) is the most common endocrine malignancy, with increasing incidence globally. Papillary thyroid cancer (PTC), a differentiated form of TC, accounts for approximately 90% of TC and occurs predominantly in women of childbearing age. Although responsive to current treatments, recurrence of PTC by middle age is common and is much more refractive to treatment. Undifferentiated TC, particularly anaplastic thyroid cancer (ATC), is the most aggressive TC subtype, characterized by it being resistant and unresponsive to all therapeutic and surgical interventions. Further, ATC is one of the most aggressive and lethal malignancies across all cancer types. Despite the differences in therapeutic needs in differentiated vs. undifferentiated TC subtypes, there is a critical unmet need for the identification of molecular biomarkers that can aid in early diagnosis, prognosis, and actionable therapeutic targets for intervention. Advances in the field of cancer genomics have enabled for the elucidation of differential gene expression patterns between tumors and healthy tissue. A novel category of molecules, known as non-coding RNAs, can themselves be differentially expressed, and extensively contribute to the up- and downregulation of protein coding genes, serving as master orchestrators of regulated and dysregulated gene expression patterns. These non-coding RNAs have been identified for their roles in driving carcinogenic patterns at various stages of tumor development and have become attractive targets for study. The identification of specific genes that are differentially expressed can give insight into mechanisms that drive carcinogenic patterns, filling the gaps of deciphering molecular and cellular processes that modulate TC subtypes, outside of well-known driver mutations.

Insights into lenvatinib resistance: mechanisms, potential biomarkers, and strategies to enhance sensitivity

Lenvatinib is a multitargeted tyrosine kinase inhibitor capable of promoting apoptosis, suppressing angiogenesis, inhibiting tumor cell proliferation, and modulating the immune response. In multiple cancer types, lenvatinib has presented manageable safety and is currently approved as an effective first-line therapy. However, with the gradual increase in lenvatinib application, the inevitable progression of resistance to lenvatinib is becoming more prevalent. A series of recent researches have reported the mechanisms underlying the development of lenvatinib resistance in tumor therapy, which are related to the regulation of cell death or proliferation, histological transformation, metabolism, transport processes, and epigenetics. In this review, we aim to outline recent discoveries achieved in terms of the mechanisms and potential predictive biomarkers of lenvatinib resistance as well as to summarize untapped approaches available for improving the therapeutic efficacy of lenvatinib in patients with various types of cancers.

Recent research progress of circular RNAs in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is an extremely heterogeneous malignant tumor with a high morbidity and mortality. Circular RNAs (circRNAs) are noncoding RNAs with high stability, organ/tissue/cell-specific expression and are conserved across species. Accumulating evidence suggested that circRNAs play crucial roles as microRNA sponges, protein sponges, scaffolds, recruiters and could even polypeptide encoders. Many studies have since revealed that circRNAs were aberrantly expressed in HCC and acted as crucial modulators of HCC carcinogenesis and progression. Furthermore, circRNAs have also been identified as potential diagnostic and prognostic biomarkers for HCC. In this review, we thoroughly outline and evaluate the function of circRNAs in HCC development, with an emphasis on the specific molecular pathways by which they participated in the formation and progression of HCC, and we address their potential for serving as clinical biomarkers in HCC.

MYC in liver cancer: mechanisms and targeted therapy opportunities

MYC, a major oncogenic transcription factor, regulates target genes involved in various pathways such as cell proliferation, metabolism and immune evasion, playing a critical role in the tumor initiation and development in multiple types of cancer. In liver cancer, MYC and its signaling pathways undergo significant changes, exerting a profound impact on liver cancer progression, including tumor proliferation, metastasis, dedifferentiation, metabolism, immune microenvironment, and resistance to comprehensive therapies. This makes MYC an appealing target, despite it being previously considered an undruggable protein. In this review, we discuss the role and mechanisms of MYC in liver physiology, chronic liver diseases, hepatocarcinogenesis, and liver cancer progression, providing a theoretical basis for targeting MYC as an ideal therapeutic target for liver cancer. We also summarize and prospect the strategies for targeting MYC, including direct and indirect approaches to abolish the oncogenic function of MYC in liver cancer.

Hepatocellular Carcinoma: Up-regulated Circular RNAs Which Mediate Efficacy in Preclinical In Vivo Models

Hepatocellular carcinoma (HCC) ranges as number two with respect to the incidence of tumors and is associated with a dismal prognosis. The therapeutic efficacy of approved multi-tyrosine kinase inhibitors and checkpoint inhibitors is modest. Therefore, the identification of new therapeutic targets and entities is of paramount importance. We searched the literature for up-regulated circular RNAs (circRNAs) which mediate efficacy in preclinical in vivo models of HCC. Our search resulted in 14 circRNAs which up-regulate plasma membrane transmembrane receptors, while 5 circRNAs induced secreted proteins. Two circRNAs facilitated replication of Hepatitis B or C viruses. Three circRNAs up-regulated high mobility group proteins. Six circRNAs regulated components of the ubiquitin system. Seven circRNAs induced GTPases of the family of ras-associated binding proteins (RABs). Three circRNAs induced redox-related proteins, eight of them up-regulated metabolic enzymes and nine circRNAs induced signaling-related proteins. The identified circRNAs up-regulate the corresponding targets by sponging microRNAs. Identified circRNAs and their targets have to be validated by standard criteria of preclinical drug development. Identified targets can potentially be inhibited by small molecules or antibody-based moieties and circRNAs can be inhibited by small-interfering RNAs (siRNAs) or short hairpin RNAs (shRNAs) for therapeutic purposes.

Application and Resistance Mechanisms of Lenvatinib in Patients with Advanced Hepatocellular Carcinoma

Lenvatinib, a multitargeted tyrosine kinase inhibitor (TKI), is one of the preferred targeted drugs for the treatment of advanced hepatocellular carcinoma (aHCC). Since the REFLECT study showed that lenvatinib was noninferior to sorafenib in overall survival (OS), lenvatinib monotherapy has been widely used for aHCC. Moreover, lenvatinib combination therapy, especially lenvatinib combined with immune checkpoint inhibitors (ICIs), has shown more encouraging clinical results. However, drug development and comprehensive treatment have not significantly improved the prognosis, and lenvatinib resistance is often encountered in treatment. The underlying molecular mechanism of lenvatinib resistance is still unclear, and studies to solve drug resistance are ongoing. The molecular mechanisms of lenvatinib resistance in patients with aHCC include the regulation of signaling pathways, the regulation of noncoding RNAs, the impact of the immune microenvironment, tumor stem cell activation and other mechanisms. This review aims to (1) summarize the progress of lenvatinib in treating aHCC, (2) delineate the known lenvatinib resistance mechanisms of current therapy, and (3) describe the development of therapeutic methods intended to overcome these resistance mechanisms.

Interactome of Long Non-Coding RNAs: Transcriptomic Expression Patterns and Shaping Cancer Cell Phenotypes

RNA biology has gained extensive recognition in the last two decades due to the identification of novel transcriptomic elements and molecular functions. Cancer arises, in part, due to the accumulation of mutations that greatly contribute to genomic instability. However, the identification of differential gene expression patterns of wild-type loci has exceeded the boundaries of mutational study and has significantly contributed to the identification of molecular mechanisms that drive carcinogenic transformation. Non-coding RNA molecules have provided a novel avenue of exploration, providing additional routes for evaluating genomic and epigenomic regulation. Of particular focus, long non-coding RNA molecule expression has been demonstrated to govern and direct cellular activity, thus evidencing a correlation between aberrant long non-coding RNA expression and the pathological transformation of cells. lncRNA classification, structure, function, and therapeutic utilization have expanded cancer studies and molecular targeting, and understanding the lncRNA interactome aids in defining the unique transcriptomic signatures of cancer cell phenotypes.

CircRNAs in osteoarthritis: research status and prospect

Osteoarthritis (OA) is the most common joint disease globally, and its progression is irreversible. The mechanism of osteoarthritis is not fully understood. Research on the molecular biological mechanism of OA is deepening, among which epigenetics, especially noncoding RNA, is an emerging hotspot. CircRNA is a unique circular noncoding RNA not degraded by RNase R, so it is a possible clinical target and biomarker. Many studies have found that circRNAs play an essential role in the progression of OA, including extracellular matrix metabolism, autophagy, apoptosis, the proliferation of chondrocytes, inflammation, oxidative stress, cartilage development, and chondrogenic differentiation. Differential expression of circRNAs was also observed in the synovium and subchondral bone in the OA joint. In terms of mechanism, existing studies have mainly found that circRNA adsorbs miRNA through the ceRNA mechanism, and a few studies have found that circRNA can serve as a scaffold for protein reactions. In terms of clinical transformation, circRNAs are considered promising biomarkers, but no large cohort has tested their diagnostic value. Meanwhile, some studies have used circRNAs loaded in extracellular vesicles for OA precision medicine. However, there are still many problems to be solved in the research, such as the role of circRNA in different OA stages or OA subtypes, the construction of animal models of circRNA knockout, and more research on the mechanism of circRNA. In general, circRNAs have a regulatory role in OA and have particular clinical potential, but further studies are needed in the future.

Erratum: Drug resistance mechanism of kinase inhibitors in the treatment of hepatocellular carcinoma

[This corrects the article DOI: 10.3389/fphar.2023.1097277.].

Circular RNA expression profile identifies circMGEA5 as a novel metastasis-promoting factor and potential biomarker in osteosarcoma

Osteosarcoma (OS) is associated with a high incidence of lung metastasis, which leads to a high risk of cancer death. Circular RNA (circRNA), a novel class of noncoding RNA, is emerging as a key player in human cancer. Herein, we explored the role of circMGEA5 in OS metastasis by conducting circRNA expression microarray. CircMGEA5 was significantly upregulated in metastatic OS tissues compared to primary tissues. High circMGEA5 was positively related with shorter overall and disease-free survival time. Knockdown of circMGEA5 suppressed OS cell migration, invasion, and epithelial-mesenchymal transition (EMT). Mechanistically, circMGEA5 acted as a competing endogenous RNA (ceRNA) to directly sponge miR-153-3p and miR-8084, resulting in increasing ZEB1 and Snail expression, respectively, thereby inducing EMT and metastasis. In turn, ZEB1 and Snail were capable to bind to circMGEA5 promoter, activating circMGEA5 transcription, thus forming a positive feedback loop. Furthermore, we established the tail vein injection model and found that circMGEA5 depletion remarkably reduced lung metastasis nodules generated by OS cells. In sum, our findings, for the first time, reveal the metastasis-promoting role of circMGEA5 in OS. Targeting of this newly identified ceRNA axis may be crucial in the development of novel therapies for metastatic OS patients.

Review of novel functions and implications of circular RNAs in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most frequent malignancies, with high incidence and mortality. As the majority of HCC patients are diagnosed at an advanced stage and die of recurrence and metastasis, its pathology and new biomarkers are needed. Circular RNAs (circRNAs) are a large subclass of long non-coding RNAs (lncRNAs) with covalently closed loop structures and abundant, conserved, stable, tissue-specific expression in mammalian cells. CircRNAs exert multiple functions in HCC initiation, growth and progression, serving as promising biomarkers for diagnosis, prognosis and therapeutic targets for this disease. This review briefly describes the biogenesis and biological functions of circRNAs and elucidates the roles of circRNAs in the development and progression of HCC, especially regarding epithelial-mesenchymal transition (EMT), drug resistance and interactions with epigenetic modifications. In addition, this review highlights the implications of circRNAs as potential biomarkers and therapeutic targets for HCC. We hope to provide novel insight into the roles of circRNAs in HCC.

The Roles of Epigenetic Regulation and the Tumor Microenvironment in the Mechanism of Resistance to Systemic Therapy in Hepatocellular Carcinoma

Primary liver cancer is the sixth most common cancer and the third most common cause of cancer-related deaths worldwide. Hepatocellular carcinoma (HCC) is a major histologic type with a poor prognosis owing to the difficulty in early detection, the chemotherapy resistance, and the high recurrence rate of the disease. Despite recent advancements in HCC prevention and diagnosis, over 50% of patients are diagnosed at Barcelona Clinic Liver Cancer Stage B or C. Systemic therapies are recommended for unresectable HCC (uHCC) with major vascular invasion, extrahepatic metastases, or intrahepatic lesions that have a limited response to transcatheter arterial chemoembolization, but the treatment outcome tends to be unsatisfactory due to acquired drug resistance. Elucidation of the mechanisms underlying the resistance to systemic therapies and the appropriate response strategies to solve this issue will contribute to improved outcomes in the multidisciplinary treatment of uHCC. In this review, we summarize recent findings on the mechanisms of resistance to drugs such as sorafenib, regorafenib, and lenvatinib in molecularly targeted therapy, with a focus on epigenetic regulation and the tumor microenvironment and outline the approaches to improve the therapeutic outcome for patients with advanced HCC.

Lenvatinib resistance mechanism and potential ways to conquer

Lenvatinib (LVN) has been appoved to treat advanced renal cell carcinoma, differentiated thyroid carcinoma, hepatocellular carcinoma. Further other cancer types also have been tried in pre-clinic and clinic without approvation by FDA. The extensive use of lenvastinib in clinical practice is sufficient to illustrate its important therapeutic role. Although the drug resistance has not arised largely in clinical, the studies focusing on the resistance of LVN increasingly. In order to keep up with the latest progress of resistance caused by LVN, we summerized the latest studies from identify published reports. In this review, we found the latest report about resistance caused by lenvatinib, which were contained the hotspot mechanism such as the epithelial-mesenchymal transition, ferroptosis, RNA modification and so on. The potential ways to conquer the resistance of LVN were embraced by nanotechnology, CRISPR technology and traditional combined strategy. The latest literature review of LVN caused resistance would bring some ways for further study of LVN. We call for more attention to the pharmacological parameters of LVN in clinic, which was rarely and would supply key elements for drug itself in human beings and help to find the resistance target or idea for further study.

Drug resistance mechanism of kinase inhibitors in the treatment of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is the most common form of primary liver cancer, and it usually occurs following chronic liver disease. Although some progress has been made in the treatment of HCC, the prognosis of patients with advanced HCC is not optimistic, mainly because of the inevitable development of drug resistance. Therefore, multi-target kinase inhibitors for the treatment of HCC, such as sorafenib, lenvatinib, cabozantinib, and regorafenib, produce small clinical benefits for patients with HCC. It is necessary to study the mechanism of kinase inhibitor resistance and explore possible solutions to overcome this resistance to improve clinical benefits. In this study, we reviewed the mechanisms of resistance to multi-target kinase inhibitors in HCC and discussed strategies that can be used to improve treatment outcomes.

Hsa_circ_0074158 regulates the endothelial barrier function in sepsis and its potential value as a biomarker

Background: Sepsis is one of the main causes of death in critically ill patients with high morbidity and mortality. Circular RNAs (CircRNAs) are aberrantly expressed, and play significant regulatory roles in many diseases. However, the expression profiles and functions of circRNAs in sepsis have not yet been fully clarified.

Methods: Our present study performed an RNA sequencing (RNA-seq) analysis to assess the expression profiles of circRNAs in vitro. We applied the quantitative real-time polymerase chain reaction (RT-qPCR) to verify the RNA-seq results. The analyses of Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, the competitive endogenous RNA (ceRNA) regulatory networks, were performed to explore the potential mechanism in sepsis. And then, significantly up-regulated differentially expressed (DE) circRNA, hsa_circ_0074158, was selected for further study. Hsa_circ_0074158 was silenced to investigate its regulatory function in sepsis, and the barrier function was also examined in vitro. Endothelial cell junctions were valued using Vascular endothelial cadherin (VE-cadherin), which was detected by immunofluorescence staining. We measured endothelial permeability by transendothelial electrical resistance (TEER) and fluorescein isothiocyanate (FITC)-dextran extravasation.

Results: In total, 203 significantly DE circRNAs, including 77 up-regulated and 126 down-regulated, were identified. In vitro, the RT-qPCR assay showed that the expression pattern of hsa_circ_0074158, hsa_circ_RSBN1L_11059, hsa_circ_0004188, and hsa_circ_0005564 were consistent with the results from RNA-seq analysis. The expression of hsa_circ_0074158 detected by RT-qPCR in vivo was also consistent with the RNA-seq results. The ceRNA networks, GO enrichment, and the KEGG pathway analyses revealed that circRNAs may be related to the barrier function in sepsis. The immunofluorescence assay showed that the suppression of hsa_circ_0074158 expression significantly enhanced the expression of VE-cadherin, which was suppressed in lipopolysaccharide (LPS)-induced sepsis. Additionally, hsa_circ_0074158 knockdown could partially reverse the LPS-induced TEER reduction and FITC-dextran extravasation elevation in sepsis.

Conclusion: In conclusion, we have found DE circRNAs could serve as potential biomarkers and therapeutic targets for sepsis. Hsa_circ_0074158 plays a vital role in sepsis and is related to the disruption of the endothelial barrier.

CircPAK1 promotes the progression of hepatocellular carcinoma via modulation of YAP nucleus localization by interacting with 14-3-3ζ

Background

Circular RNA (circRNA), a new class of non-coding RNA, has obvious correlations with the occurrence and development of many diseases, including tumors. This study aimed to investigate the potential roles of circPAK1 in hepatocellular carcinoma (HCC).

Methods

High-throughput sequencing was performed on 3 pairs of HCC and matched normal tissues to determine the upregulated circRNAs. The expression level of circPAK1 was detected by qRT-PCR in HCC and paired with normal liver tissue samples. The effects of circPAK1 on proliferation, invasion, metastasis and apoptosis of HCC cells were evaluated by in vitro and in vivo experiments. We also constructed Chitosan/si-circPAK1 (CS/si-circPAK1) nanocomplexes using Chitosan material to evaluate its in vivo therapeutic effect on HCC. High-throughput sequencing, RNA-sequencing, RNA probe pull-down, RNA immunoprecipitation and Co-Immunoprecipitation assays were performed to explore the relationship between circPAK1, 14–3-3ζ, p-LATS1 and YAP. Exosomes isolated from lenvatinib-resistant HCC cell lines were used to evaluate the relationship between exosomal circPAK1 and lenvatinib resistance.

Results

CircPAK1, a novel circRNA, is highly expressed in HCC tumor tissues and cell lines as well as correlated with poor outcomes in HCC patients. Functionally, circPAK1 knockdown inhibited HCC cell proliferation, migration, invasion and angiogenesis while circPAK1 overexpression promoted HCC progression. The tumor-promoting phenotypes of circPAK1 on HCC were also confirmed by animal experiments. Importantly, the application of CS/si-circPAK1 nanocomplexes showed a better therapeutic effect on tumor growth and metastasis. Mechanistically, circPAK1 enhanced HCC progression by inactivating the Hippo signaling pathway, and this kind of inactivation is based on its competitively binding of 14–3-3 ζ with YAP, which weakens the recruitment and cytoplasmic fixation of 14–3-3 ζ to YAP, thus promoting YAP nucleus localization. Additionally, circPAK1 could be transported by exosomes from lenvatinib-resistant cells to sensitive cells and induce lenvatinib resistance of receipt cells.

Conclusion

CircPAK1 exerts its oncogenic function by competitively binding 14–3-3 ζ with YAP, thus promoting YAP nucleus localization, leading to the inactivation of a Hippo signaling pathway. Exosomal circPAK1 may drive resistance to lenvatinib, providing a potential therapeutic target for HCC patients.

New insights into antiangiogenic therapy resistance in cancer: Mechanisms and therapeutic aspects

Angiogenesis is a hallmark of cancer and is required for tumor growth and progression. Antiangiogenic therapy has been revolutionarily developing and was approved for the treatment of various types of cancer for nearly two decades, among which bevacizumab and sorafenib continue to be the two most frequently used antiangiogenic drugs. Although antiangiogenic therapy has brought substantial survival benefits to many cancer patients, resistance to antiangiogenic drugs frequently occurs during clinical treatment, leading to poor outcomes and treatment failure. Cumulative evidence has demonstrated that the intricate interplay among tumor cells, bone marrow-derived cells, and local stromal cells critically allows for tumor escape from antiangiogenic therapy. Currently, drug resistance has become the main challenge that hinders the therapeutic efficacies of antiangiogenic therapy. In this review, we describe and summarize the cellular and molecular mechanisms conferring tumor drug resistance to antiangiogenic therapy, which was predominantly associated with redundancy in angiogenic signaling molecules (e.g., VEGFs, GM-CSF, G-CSF, and IL17), alterations in biological processes of tumor cells (e.g., tumor invasiveness and metastasis, stemness, autophagy, metabolic reprogramming, vessel co-option, and vasculogenic mimicry), increased recruitment of bone marrow-derived cells (e.g., myeloid-derived suppressive cells, tumor-associated macrophages, and tumor-associated neutrophils), and changes in the biological functions and features of local stromal cells (e.g., pericytes, cancer-associated fibroblasts, and endothelial cells). We also review potential biomarkers to predict the response to antiangiogenic therapy in cancer patients, which mainly consist of imaging biomarkers, cellular and extracellular proteins, a certain type of bone marrow-derived cells, local stromal cell content (e.g., pericyte coverage) as well as serum or plasma biomarkers (e.g., non-coding RNAs). Finally, we highlight the recent advances in combination strategies with the aim of enhancing the response to antiangiogenic therapy in cancer patients and mouse models. This review introduces a comprehensive understanding of the mechanisms and biomarkers associated with the evasion of antiangiogenic therapy in cancer, providing an outlook for developing more effective approaches to promote the therapeutic efficacy of antiangiogenic therapy.