MicroRNA-128-3p Mediates Lenvatinib Resistance of Hepatocellular Carcinoma Cells by Downregulating c-Met

miRNAs in HCC, pathogenesis, and targets

Liver cancer is the third leading cause of cancer-related mortality worldwide. HCC, the most common type of primary liver cancer, is driven by complex genetic, epigenetic, and environmental factors. MicroRNAs, a class of naturally occurring small noncoding RNAs, play crucial roles in HCC by simultaneously modulating the expression of multiple genes in a fine-tuning manner. Significant progress has been made in understanding how miRNAs influence key oncogenic pathways, including cell proliferation, apoptosis, angiogenesis, and epithelial-mesenchymal transition (EMT), as well as their role in modulating the immune microenvironment in HCC. Due to the unexpected stability of miRNAs in the blood and fixed HCC tumors, recent advancements also highlight their potential as noninvasive diagnostic tools. Restoring or inhibiting specific miRNAs has offered promising strategies for targeted HCC treatment by suppressing malignant hepatocyte growth and enhancing antitumor immunity. In this comprehensive review, we consolidate previous research and provide the latest insights into how miRNAs regulate HCC and their therapeutic and diagnostic potential. We delve into the dysregulation of miRNA biogenesis in HCC, the roles of miRNAs in the proliferation and apoptosis of malignant hepatocytes, angiogenesis and metastasis of HCC, the immune microenvironment in HCC, and drug resistance. We also discuss the therapeutic and diagnostic potential of miRNAs and delivery approaches of miRNA drugs to overcome the limitations of current HCC treatment options. By thoroughly summarizing the roles of miRNAs in HCC, our goal is to advance the development of effective therapeutic drugs with minimal adverse effects and to establish precise tools for early diagnosis of HCC.

MicroRNAs in Hepatocellular Carcinoma: Insights into Regulatory Mechanisms, Clinical Significance, and Therapeutic Potential

Hepatocellular carcinoma (HCC) is one of the most common malignant tumors. Tumor immune microenvironment (TIME), angiogenesis, epithelial-mesenchymal transformation (EMT), invasion, metastasis, metabolism, and drug resistance are the main factors affecting the development and treatment of tumors. MiRNAs play crucial roles in almost all major cellular biological processes. Studies have been carried out on miRNAs as biomarkers and therapeutic targets. Their dysregulation contributes to the progression and prognosis of HCC. This review aims to explore the molecular cascades and corresponding phenotypic changes caused by aberrant miRNA expression and their regulatory mechanisms, summarize and analyze novel biomarkers from somatic fluids (plasma/serum/urine), and highlight the latent capacity of miRNAs as therapeutic targets.

SPG21, a potential oncogene targeted by miR-128-3p, amplifies HBx-induced carcinogenesis and chemoresistance via activation of TRPM7-mediated JNK pathway in hepatocellular carcinoma

PURPOSE

Chronic hepatitis B virus (HBV) infection is the primary risk factor for the malignant progression of hepatocellular carcinoma (HCC). It has been reported that HBV X protein (HBx) possesses oncogenic properties, promoting hepatocarcinogenesis and chemoresistance. However, the detailed molecular mechanisms are not fully understood. Here, we aim to investigate the effects of miR-128-3p/SPG21 axis on HBx-induced hepatocarcinogenesis and chemoresistance.

METHODS

The expression of SPG21 in HCC was determined using bioinformatics analysis, quantitative real-time PCR (qRT-PCR), western blotting, and immunohistochemistry (IHC). The roles of SPG21 in HCC were elucidated through a series of in vitro and in vivo experiments, including real-time cellular analysis (RTCA), matrigel invasion assay, and xenograft mouse model. Pharmacologic treatment and flow cytometry were performed to demonstrate the potential mechanism of SPG21 in HCC.

RESULTS

SPG21 expression was elevated in HCC tissues compared to adjacent non-tumor tissues (NTs). Moreover, higher SPG21 expression correlated with poor overall survival. Functional assays revealed that SPG21 fostered HCC tumorigenesis and invasion. MiR-128-3p, which targeted SPG21, was downregulated in HCC tissues. Subsequent analyses showed that HBx amplified TRPM7-mediated calcium influx via miR-128-3p/SPG21, thereby activating the c-Jun N-terminal kinase (JNK) pathway. Furthermore, HBx inhibited doxorubicin-induced apoptosis by engaging the JNK pathway through miR-128-3p/SPG21.

CONCLUSION

The study suggested that SPG21, targeted by miR-128-3p, might be involved in enhancing HBx-induced carcinogenesis and doxorubicin resistance in HCC via the TRPM7/Ca2+/JNK signaling pathway. This insight suggested that SPG21 could be recognized as a potential oncogene, offering a novel perspective on its role as a prognostic factor and a therapeutic target in the context of HCC.

Dual effects of targeting neuropilin-1 in lenvatinib-resistant hepatocellular carcinoma: inhibition of tumor growth and angiogenesis

In the era of immunotherapy, lenvatinib (LEN) still holds an important position in the sequential treatment of advanced hepatocellular carcinoma (HCC). However, the sustained therapeutic effect of LEN is not sufficient, and there is a need to address the development of resistance. Neuropilin-1 (NRP1) is known to act as a coreceptor for epidermal growth factor receptor (EGFR), Met, and vascular endothelial growth factor receptor 2 (VEGFR2), which have been reported to be involved in LEN resistance. In this study, we used cell culture and in vivo xenograft models to evaluate the contribution of NRP1 in the acquisition of LEN resistance in HCC as well as the potential of NRP1 as a therapeutic target. LEN resistance increased EGF/EGFR and hepatocyte growth factor (HGF)/Met signaling in liver cancer cells and VEGFA/VEGFR2 and HGF/Met signaling in vascular endothelial cells, thereby promoting cell proliferation, cell migration, and angiogenesis. We found that activation of NRP1 is essential for the enhancement of these signaling. In addition, NRP1 inhibition combined with LEN therapy synergistically improved the antitumor effects against LEN-resistant HCC, indicating that NRP1 is an attractive therapeutic target.NEW & NOTEWORTHY We demonstrated that neuropilin-1 (NRP1) was an essential coreceptor mediating the activation of multiple signaling pathways in the acquisition of resistance to lenvatinib (LEN) in HCC. The addition of NRP1 inhibition to LEN had a synergistic antitumor effect on LEN-resistant HCC in culture and in vivo xenograft models.

Roles of clinical application of lenvatinib and its resistance mechanism in advanced hepatocellular carcinoma (Review)

Lenvatinib (LEN) is a multi-target TKI, which plays a pivotal role in the treatment of advanced hepatocellular carcinoma (HCC). The inevitable occurrence of drug resistance still prevents curative potential and is deleterious for the prognosis, and a growing body of studies is accumulating, which have devoted themselves to unveiling its underlying resistance mechanism and made some progress. The dysregulation of crucial signaling pathways, non-coding RNA and RNA modifications were proven to be associated with LEN resistance. A range of drugs were found to influence LEN therapeutic efficacy. In addition, the superiority of LEN combination therapy has been shown to potentially overcome the limitations of LEN monotherapy in a series of research, and a range of promising indicators for predicting treatment response and prognosis have been discovered in recent years. In this review, we summarize the latest developments in LEN resistance, the efficacy and safety of LEN combination therapy as well as associated indicators, which may provide new insight into its resistance as well as ideas in the treatment of advanced HCC.

MicroRNAs in Hepatocellular Carcinoma Pathogenesis: Insights into Mechanisms and Therapeutic Opportunities

Hepatocellular carcinoma (HCC) presents a significant global health burden, with alarming statistics revealing its rising incidence and high mortality rates. Despite advances in medical care, HCC treatment remains challenging due to late-stage diagnosis, limited effective therapeutic options, tumor heterogeneity, and drug resistance. MicroRNAs (miRNAs) have attracted substantial attention as key regulators of HCC pathogenesis. These small non-coding RNA molecules play pivotal roles in modulating gene expression, implicated in various cellular processes relevant to cancer development. Understanding the intricate network of miRNA-mediated molecular pathways in HCC is essential for unraveling the complex mechanisms underlying hepatocarcinogenesis and developing novel therapeutic approaches. This manuscript aims to provide a comprehensive review of recent experimental and clinical discoveries regarding the complex role of miRNAs in influencing the key hallmarks of HCC, as well as their promising clinical utility as potential therapeutic targets.

New insights into the mechanism of resistance to lenvatinib and strategies for lenvatinib sensitization in hepatocellular carcinoma

Lenvatinib is a multikinase inhibitor that suppresses vascular endothelial growth factor receptor (VEGFR), fibroblast growth factor receptor (FGFR), platelet-derived growth factor receptor α (PDGFRα), as well as the proto-oncogenes RET and KIT. Lenvatinib has been approved by the US Food and Drug Administration (FDA) for the first-line treatment of hepatocellular carcinoma (HCC) due to its superior efficacy when compared to sorafenib. Unfortunately, the development of drug resistance to lenvatinib is becoming increasingly common. Thus, there is an urgent need to identify the factors that lead to drug resistance and ways to mitigate it. We summarize the molecular mechanisms that lead to lenvatinib resistance (LR) in HCC, which involve programmed cell death (PCD), translocation processes, and changes in the tumor microenvironment (TME), and provide strategies to reverse resistance.

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.

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.

Mechanisms of drug resistance in HCC

HCC comprises ∼80% of primary liver cancer. HCC is the only major cancer for which death rates have not improved over the last 10 years. Most patients are diagnosed with advanced disease when surgical and locoregional treatments are not feasible or effective. Sorafenib, a multikinase inhibitor targeting cell growth and angiogenesis, was approved for advanced unresectable HCC in 2007. Since then, other multikinase inhibitors have been approved. Lenvatinib was found to be noninferior to sorafenib as a first-line agent. Regorafenib, cabozantinib, and ramucirumab were shown to prolong survival as second-line agents. Advances in immunotherapy for HCC have also added hope for patients, but their efficacy remains limited. A large proportion of patients with advanced HCC gain no long-term benefit from systemic therapy due to primary and acquired drug resistance, which, combined with its rising incidence, keeps HCC a highly fatal disease. This review summarizes mechanisms of primary and acquired resistance to therapy and includes methods for bypassing resistance. It addresses recent advancements in immunotherapy, provides new perspectives on the linkage between drug resistance and molecular etiology of HCC, and evaluates the role of the microbiome in drug resistance. It also discusses alterations in signaling pathways, dysregulation of apoptosis, modulations in the tumor microenvironment, involvement of cancer stem cells, changes in drug metabolism/transport, tumor hypoxia, DNA repair, and the role of microRNAs in drug resistance. Understanding the interplay among these factors will provide guidance on the development of new therapeutic strategies capable of improving patient outcomes.

Noncoding RNAs in Hepatocellular Carcinoma: Potential Applications in Combined Therapeutic Strategies and Promising Candidates of Treatment Response

The incidence of hepatocellular carcinoma (HCC) is increasing, and 40% of patients are diagnosed at advanced stages. Over the past 5 years, the number of clinically available treatments has dramatically increased for HCC, making patient management particularly complex. Immune checkpoint inhibitors (ICIs) have improved the overall survival of patients, showing a durable treatment benefit over time and a different response pattern with respect to tyrosine kinase inhibitors (TKIs). Although there is improved survival in responder cases, a sizeable group of patients are primary progressors or are ineligible for immunotherapy. Indeed, patients with nonviral etiologies, such as nonalcoholic steatohepatitis (NASH), and alterations in specific driver genes might be less responsive to immunotherapy. Therefore, improving the comprehension of mechanisms of drug resistance and identifying biomarkers that are informative of the best treatment approach are required actions to improve patient survival. Abundant evidence indicates that noncoding RNAs (ncRNAs) are pivotal players in cancer. Molecular mechanisms through which ncRNAs exert their effects in cancer progression and drug resistance have been widely investigated. Nevertheless, there are no studies summarizing the synergistic effect between ncRNA-based strategies and TKIs or ICIs in the preclinical setting. This review aims to provide up-to-date information regarding the possible use of ncRNAs as therapeutic targets in association with molecular-targeted agents and immunotherapies and as predictive tools for the selection of optimized treatment options in advanced HCCs.

New Opportunities in the Systemic Treatment of Hepatocellular Carcinoma-Today and Tomorrow

Hepatocellular carcinoma (HCC) is the most common primary liver cancer. Liver cirrhosis, hepatitis B, hepatitis C, and non-alcoholic fatty liver disease represent major risk factors of HCC. Multiple different treatment options are available, depending on the Barcelona Clinic Liver Cancer (BCLC) algorithm. Systemic treatment is reserved for certain patients in stages B and C, who will not benefit from regional treatment methods. In the last fifteen years, the arsenal of available therapeutics has largely expanded, which improved treatment outcomes. Nevertheless, not all patients respond to these agents and novel combinations and drugs are needed. In this review, we aim to summarize the pathway of trials investigating the safety and efficacy of targeted therapeutics and immunotherapies since the introduction of sorafenib. Furthermore, we discuss the current evidence regarding resistance mechanisms and potential novel targets in the treatment of advanced HCC.

The action and resistance mechanisms of Lenvatinib in liver cancer

Lenvatinib is a tyrosine kinase inhibitor that prevents the formation of new blood vessels namely by inhibiting tyrosine kinase enzymes as the name suggests. Specifically, Lenvatinib acts on vascular endothelial growth factor receptors 1-3 (VEGFR1-3), fibroblast growth factor receptors 1-4 (FGFR1-4), platelet-derived growth factor receptor-alpha (PDGFRα), tyrosine-kinase receptor (KIT), and rearranged during transfection receptor (RET). Inhibition of these receptors works to inhibit tumor proliferation. It is through these inhibition mechanisms that Lenvatinib was tested to be noninferior to Sorafenib. However, resistance to Lenvatinib is common, making the positive effects of Lenvatinib on a patient's survival null after resistance is acquired. Therefore, it is crucial to understand mechanisms related to Lenvatinib resistance. This review aims to piece together various mechanisms involved in Lenvatinib resistance and summarizes the research done so far investigating it.

Role of Non-Coding RNAs in Hepatocellular Carcinoma Progression: From Classic to Novel Clinicopathogenetic Implications

Hepatocellular carcinoma (HCC) is a predominant malignancy with increasing incidences and mortalities worldwide. In Western countries, the progressive affirmation of Non-alcoholic Fatty Liver Disease (NAFLD) as the main chronic liver disorder in which HCC occurrence is appreciable even in non-cirrhotic stages, constitutes a real health emergency. In light of this, a further comprehension of molecular pathways supporting HCC onset and progression represents a current research challenge to achieve more tailored prognostic models and appropriate therapeutic approaches. RNA non-coding transcripts (ncRNAs) are involved in the regulation of several cancer-related processes, including HCC. When dysregulated, these molecules, conventionally classified as "small ncRNAs" (sncRNAs) and "long ncRNAs" (lncRNAs) have been reported to markedly influence HCC-related progression mechanisms. In this review, we describe the main dysregulated ncRNAs and the relative molecular pathways involved in HCC progression, analyzing their implications in certain etiologically related contexts, and their applicability in clinical practice as novel diagnostic, prognostic, and therapeutic tools. Finally, given the growing evidence supporting the immune system response, the oxidative stress-regulated mechanisms, and the gut microbiota composition as relevant emerging elements mutually influencing liver-cancerogenesis processes, we investigate the relationship of ncRNAs with this triad, shedding light on novel pathogenetic frontiers of HCC progression.

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.

Epigenetic reactivation of tumor suppressor genes with CRISPRa technologies as precision therapy for hepatocellular carcinoma

BACKGROUND

Epigenetic silencing of tumor suppressor genes (TSGs) is a key feature of oncogenesis in hepatocellular carcinoma (HCC). Liver-targeted delivery of CRISPR-activation (CRISPRa) systems makes it possible to exploit chromatin plasticity, by reprogramming transcriptional dysregulation.

RESULTS

Using The Cancer Genome Atlas HCC data, we identify 12 putative TSGs with negative associations between promoter DNA methylation and transcript abundance, with limited genetic alterations. All HCC samples harbor at least one silenced TSG, suggesting that combining a specific panel of genomic targets could maximize efficacy, and potentially improve outcomes as a personalized treatment strategy for HCC patients. Unlike epigenetic modifying drugs lacking locus selectivity, CRISPRa systems enable potent and precise reactivation of at least 4 TSGs tailored to representative HCC lines. Concerted reactivation of HHIP, MT1M, PZP, and TTC36 in Hep3B cells inhibits multiple facets of HCC pathogenesis, such as cell viability, proliferation, and migration.

CONCLUSIONS

By combining multiple effector domains, we demonstrate the utility of a CRISPRa toolbox of epigenetic effectors and gRNAs for patient-specific treatment of aggressive HCC.

Evaluation and Application of Drug Resistance by Biomarkers in the Clinical Treatment of Liver Cancer

Liver cancer is one of the most lethal cancers in the world, mainly owing to the lack of effective means for early monitoring and treatment. Accordingly, there is considerable research interest in various clinically applicable methods for addressing these unmet needs. At present, the most commonly used biomarker for the early diagnosis of liver cancer is alpha-fetoprotein (AFP), but AFP is sensitive to interference from other factors and cannot really be used as the basis for determining liver cancer. Treatment options in addition to liver surgery (resection, transplantation) include radiation therapy, chemotherapy, and targeted therapy. However, even more expensive targeted drug therapies have a limited impact on the clinical outcome of liver cancer. One of the big reasons is the rapid emergence of drug resistance. Therefore, in addition to finding effective biomarkers for early diagnosis, an important focus of current discussions is on how to effectively adjust and select drug strategies and guidelines for the treatment of liver cancer patients. In this review, we bring this thought process to the drug resistance problem faced by different treatment strategies, approaching it from the perspective of gene expression and molecular biology and the possibility of finding effective solutions.

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.

Long Non-Coding RNA GAS5 Promotes BAX Expression by Competing with microRNA-128-3p in Response to 5-Fluorouracil

The acquisition of drug resistance is a major hurdle for effective cancer treatment. Although several efforts have been made to overcome drug resistance, the underlying mechanisms have not been fully elucidated. This study investigated the role of long non-coding RNA (lncRNA) growth arrest-specific 5 (GAS5) in drug resistance. GAS5 was found to be downregulated in colon cancer cell lines that are resistant to 5-fluorouracil (5-FU). Downregulation of GAS5 decreased the viability of HCT116 cells and the level of the pro-apoptotic BAX protein, while GAS5 overexpression promoted cell death in response to 5-FU. The interaction between GAS5 and BAX mRNA was investigated using MS2-tagged RNA affinity purification (MS2-trap) followed by RT-qPCR, and the results showed that GAS5 bound to the 3'-untranslated region of BAX mRNA and enhanced its expression by interfering with the inhibitory effect of microRNA-128-3p, a negative regulator of BAX. In addition, ectopic expression of GAS5 increased the sensitivity of resistant cells in response to anti-cancer drugs. These results suggest that GAS5 promoted cell death by interfering with miR-128-3p-mediated BAX downregulation. Therefore, GAS5 overexpression in chemo-resistant cancer cells may be a potential strategy to improve the anti-cancer efficacy of drugs.

Antitumor Effect of Pseudolaric Acid B Involving Regulation of Notch1/Akt Signaling Response in Human Hepatoma Cell In Vitro

Background

Liver cancer, particularly hepatocellular carcinoma (HCC), is the fourth leading cause of cancer-related death worldwide. Sorafenib is a crucial drug for the treatment of advanced HCC, but it is difficult to meet the challenge of increasing clinical demands due to its severe side effects and drug resistance. Hence, development of novel antitumor drugs is urged. Previous studies showed that pseudolaric acid B (PAB) could reduce the expression of protein kinase B (PKB/Akt), a downstream effector of Notch signaling, facilitating cell apoptosis in HCC. The disruption of Notch signaling was verified to exacerbate malignant progression and drug resistance, however, the antitumor effect of PAB on Notch signaling in HCC remains unclear. Thus, this study aims to investigate the anti-HCC effect of PAB in association with the regulation of Notch1/Akt signaling.

Methods

CCK-8 assay and transwell assay were used to examine the cell proliferation and invasion in Huh7 cells after treatment with PAB and a Notch inhibitor DAPT. Moreover, the cell cycle of Huh7 cells after treatment with PAB was analyzed using flow cytometry. Finally, the changes of Notch1, Jagged1, Hes1, and Akt expression at the protein and mRNA level in Notch1/Akt signaling in Huh7 cells after treatment with PAB and DAPT were analyzed using immunofluorescence assay and real-time qPCR.

Results

The proliferation rate of Huh7 cells exposed to PAB of 0.5, 1, 2, 4, 8, 10, 20, 40, 80, 100, and 200 μmol/L revealed a time-and dose-dependent decrease in vitro, showing cell cycle arrest at G2/M phase (P < 0.05). Furthermore, compared with the untreated group, at the concentration of 40 μmol/L, the proliferation rate and invasion rate of Huh7 cells in PAB, DAPT, and PAB-DAPT combination (PAB + DAPT) group were significantly decreased (P < 0.05), but the PAB + DAPT showed no synergistic antiproliferation and anti-invasion effect in comparison with PAB treatment alone (P > 0.05). In addition, compared with the untreated group, PAB and DAPT alone significantly downregulated the expression of Notch1, Jagged1, Hes1, Akt mRNA, or/and protein in Huh7 cells (P < 0.05), but there was no significant difference in synergistic downregulated effect between the PAB + DAPT group and the PAB group (P > 0.05).

Conclusion

PAB can suppress proliferation and invasion of HCC cells through downregulating the expression of Notch1/Akt signaling protein and mRNA, and may be a potential novel antitumor drug candidate for the clinical treatment of HCC in the future.