Inhibition of cyclin E1 sensitizes hepatocellular carcinoma cells to regorafenib by mcl-1 suppression

PROTACs: Current and Future Potential as a Precision Medicine Strategy to Combat Cancer

Proteolysis targeting chimeras (PROTAC) are an emerging precision medicine strategy, which targets key proteins for proteolytic degradation to ultimately induce cancer cell killing. These hetero-bifunctional molecules hijack the ubiquitin proteasome system to selectively add polyubiquitin chains onto a specific protein target to induce proteolytic degradation. Importantly, PROTACs have the capacity to target virtually any intracellular and transmembrane protein for degradation, including oncoproteins previously considered undruggable, which strategically positions PROTACs at the crossroads of multiple cancer research areas. In this review, we present normal functions of the ubiquitin regulation proteins and describe the application of PROTACs to improve the efficacy of current broad-spectrum therapeutics. We subsequently present the potential for PROTACs to exploit specific cancer vulnerabilities through synthetic genetic approaches, which may expedite the development, translation, and utility of novel synthetic genetic therapies in cancer. Finally, we describe the challenges associated with PROTACs and the ongoing efforts to overcome these issues to streamline clinical translation. Ultimately, these efforts may lead to their routine clinical use, which is expected to revolutionize cancer treatment strategies, delay familial cancer onset, and ultimately improve the lives and outcomes of those living with cancer.

Anti-hepatocellular carcinoma activity of the cyclin-dependent kinase inhibitor AT7519

Hepatocellular carcinoma (HCC) is one of the most common cancerous tumors and one of the leading causes of death among cancer-related disorders. Chemotherapy is ineffective in HCC patients, and the number of drugs that are in use is limited. Thus, new molecules are needed that could increase the effectiveness of anti-HCC regimens. Here, we show that AT7519, a CDK inhibitor, exerts positive effects on HCC cells: it inhibits proliferation, migration and clonogenicity. Detailed analysis of the transcriptomes of cells treated with this compound indicated that AT7519 affects a substantial portion of genes that are associated with HCC development and progression. Moreover, we showed that the concomitant use of AT7519 with gefitinib or cabozantinib sensitized HCC cells to these drugs. Thus, our research indicates that AT7519 is worth considering in monotherapy for hepatocellular carcinoma patients or in combination with other drugs, e.g., gefitinib or cabozantinib.

FBXL16 Promotes Endometrial Progesterone Resistance via PP2AB55α/Cyclin D1 Axis in Ishikawa

Background

F-box proteins are essential components of the E3 ubiquitin ligases which are involved in the regulation of almost all life activities such as cell cycle, proliferation, and apoptosis, which have become an important research and drug target. However, there are few studies on F-box and leucine-rich repeat protein 16 (FBXL16) in endometrial carcinoma.

Methods

Clinical samples were collected for determining the correlation between FBXL16 and endometrial carcinoma. Cells were screened and established with Ishikawa cells which proved the fundamental role of FBXL16 in regulating cell proliferation and cell cycle. The MPA-resistant endometrial carcinoma cell line Ishikawa/MPA was established. FBXL16, PP2A^B55α, and cyclin D1 were analyzed separately in MPA sensitive and resistant Ishikawa cells in vitro and in vivo.

Results

The high expression of FBXL16 was positively correlated with MPA resistance and poor prognosis of endometrial cancer. MPA tolerance of endometrial cancer cells was inhibited by knockdown of FBXL16 in DNA content assessment, CCK-8, and colony formation. It was confirmed that FBXL16 inhibited the activity of substrate PP2A^B55α by binding to PP2A, reduced the phosphorylation level at Thr308 site of AKT1, inhibited the expression of GSK-3β, and thus led to a significant decrease in the phosphorylation level of cyclin D1, which prevented the ubiquitination recognition and degradation of cyclin D1.

Conclusion

In our experiments, FBXL16 binds PP2A to promote the dephosphorylation of Thr286 site of cyclin D1 via AKT1/GSK3β/cyclin D1 pathway, which is required for resisting the ubiquitination degradation and enhances the MPA resistance of Ishikawa.

Dinitramine induces implantation failure by cell cycle arrest and mitochondrial dysfunction in porcine trophectoderm and luminal epithelial cells

The herbicide market is growing rapidly, as weed control is a significant challenge in agriculture. Many studies have reported the toxicity of herbicides to non-target organisms. Dinitramine is a dinitroaniline herbicide that is particularly toxic to aquatic organisms. However, little is known about the effects of dinitramine on the female reproductive system. Therefore, in the present study, we utilized porcine trophectoderm (pTr) cells and porcine endometrial luminal epithelial (pLE) cells to verify the reproductive toxicity of dinitramine. Dinitramine reduced the viability of both cell types, by triggering cell cycle arrest, especially at the sub-G1 phase, and increasing apoptosis, inhibiting DNA replication. Dinitramine disrupted intracellular calcium homeostasis and induced oxidative stress by producing reactive oxygen species, leading to the loss of mitochondrial membrane potential and alteration of mitochondrial respiration. Mitogen-activated protein kinase pathways were altered, and migration decreased in pTr and pLE cells after dinitramine treatment; the expression of pregnancy-related genes in these cells was decreased. Thus, dinitramine reduced the viability and migratory capacity of both cell types, and this could interrupt the early stages of pregnancy.

Integrative proteogenomic characterization of hepatocellular carcinoma across etiologies and stages

Proteogenomic analyses of hepatocellular carcinomas (HCC) have focused on early-stage, HBV-associated HCCs. Here we present an integrated proteogenomic analysis of HCCs across clinical stages and etiologies. Pathways related to cell cycle, transcriptional and translational control, signaling transduction, and metabolism are dysregulated and differentially regulated on the genomic, transcriptomic, proteomic and phosphoproteomic levels. We describe candidate copy number-driven driver genes involved in epithelial-to-mesenchymal transition, the Wnt-β-catenin, AKT/mTOR and Notch pathways, cell cycle and DNA damage regulation. The targetable aurora kinase A and CDKs are upregulated. CTNNB1 and TP53 mutations are associated with altered protein phosphorylation related to actin filament organization and lipid metabolism, respectively. Integrative proteogenomic clusters show that HCC constitutes heterogeneous subgroups with distinct regulation of biological processes, metabolic reprogramming and kinase activation. Our study provides a comprehensive overview of the proteomic and phophoproteomic landscapes of HCCs, revealing the major pathways altered in the (phospho)proteome.

Proteogenomic analyses of hepatocellular carcinomas (HCC) have focused on early-stage, HBV-associated tumours and lacked information about the phosphoproteome. Here, the authors present a comprehensive HCC proteogenomics and phosphoproteomics study in patient samples from multiple etiologies and stages.

Nanomedicine in Hepatocellular Carcinoma: A New Frontier in Targeted Cancer Treatment

Hepatocellular carcinoma (HCC) is the third leading cause of cancer-related death and is associated with a dismal median survival of 2-9 months. The fundamental limitations and ineffectiveness of current HCC treatments have led to the development of a vast range of nanotechnologies with the goal of improving the safety and efficacy of treatment for HCC. Although remarkable success has been achieved in nanomedicine research, there are unique considerations such as molecular heterogeneity and concomitant liver dysfunction that complicate the translation of nanotheranostics in HCC. This review highlights the progress, challenges, and targeting opportunities in HCC nanomedicine based on the growing literature in recent years.

Cyclin E1 in Murine and Human Liver Cancer: A Promising Target for Therapeutic Intervention during Tumour Progression

Simple Summary

The cell cycle regulator Cyclin E1 is a key mediator and biomarker of liver cancer progression in mice and man independent of its canonical interacting partner Cyclin-dependent kinase 2. Over-expression of Cyclin E1 during hepatocarcinogenesis modulates several distinct biological processes such as proliferation, DNA damage response, stemness, invasion and the tumour microenvironment. Interventional depletion of Cyclin E1 in the course of liver cancer progression significantly reduces tumour burden. In contrast, the expression of Cyclin-dependent kinase 2 is dispensable for the progression of liver cancer in mice and lacked diagnostic or prognostic value in patients. Thus, specific inhibition of Cyclin E1 expression represents a promising strategy for the treatment of liver cancer.

Abstract

Cyclin E1 (CCNE1) is a regulatory subunit of Cyclin-dependent kinase 2 (CDK2) and is thought to control the transition of quiescent cells into cell cycle progression. Recently, we identified CCNE1 and CDK2 as key factors for the initiation of hepatocellular carcinoma (HCC). In the present study, we dissected the contributions of CCNE1 and CDK2 for HCC progression in mice and patients. Therefore, we generated genetically modified mice allowing inducible deletion of Ccne1 or Cdk2. After initiation of HCC, using the hepatocarcinogen diethylnitrosamine (DEN), we deleted Ccne1 or Cdk2 and subsequently analysed HCC progression. The relevance of CCNE1 or CDK2 for human HCC progression was investigated by in silico database analysis. Interventional deletion of Ccne1, but not of Cdk2, substantially reduced the HCC burden in mice. Ccne1-deficient HCCs were characterised by attenuated proliferation, impaired DNA damage response and downregulation of markers for stemness and microinvasion. Additionally, the tumour microenvironment of Ccne1-deficient mice showed a reduction in immune mediators, myeloid cells and cancer-associated fibroblasts. In sharp contrast, Cdk2 was dispensable for HCC progression in mice. In agreement with our mouse data, CCNE1 was overexpressed in HCC patients independent of risk factors, and associated with reduced disease-free survival, a common signature for enhanced chromosomal instability, proliferation, dedifferentiation and invasion. However, CDK2 lacked diagnostic or prognostic value in HCC patients. In summary, CCNE1 drives HCC progression in a CDK2-independent manner in mice and man. Therefore, interventional inactivation of CCNE1 represents a promising strategy the treatment of liver cancer.

Identification of hub genes associated with prognosis, diagnosis, immune infiltration and therapeutic drug in liver cancer by integrated analysis

Background

Liver cancer is one of the most common cancers and causes of cancer death worldwide. The objective was to elucidate novel hub genes which were benefit for diagnosis, prognosis, and targeted therapy in liver cancer via integrated analysis.

Methods

GSE84402, GSE101685, and GSE112791 were filtered from the Gene Expression Omnibus (GEO). Differentially expressed genes (DEGs) were identified by using the GEO2R. The GO and KEGG pathway of DEGs were analyzed in the DAVID. PPI and TF network of the DEGs were constructed by using the STRING, TRANSFAC, and Harmonizome. The relationship between hub genes and prognoses in liver cancer was analyzed in UALCAN based on The Cancer Genome Atlas (TCGA). The diagnostic value of hub genes was evaluated by ROC. The relationship between hub genes and tumor-infiltrate lymphocytes was analyzed in TIMER. The protein levels of hub genes were verified in HPA. The interaction between the hub genes and the drug were identified in DGIdb.

Results

In total, 108 upregulated and 60 downregulated DEGs were enriched in 148 GO terms and 20 KEGG pathways. The mRNA levels and protein levels of CDK1, HMMR, PTTG1, and TTK were higher in liver cancer tissues compared to normal tissues, which showed excellent diagnostic and prognostic value. CDK1, HMMR, PTTG1, and TTK were positively correlated with tumor-infiltrate lymphocytes, which might involve tumor immune response. The CDK1, HMMR, and TTK had close interaction with anticancer agents.

Conclusions

The CDK1, HMMR, PTTG1, and TTK were hub genes in liver cancer; hence, they might be potential biomarkers for diagnosis, prognosis, and targeted therapy of liver cancer.

Targeting transcription of MCL-1 sensitizes HER2-amplified breast cancers to HER2 inhibitors

Human epidermal growth factor receptor 2 gene (HER2) is focally amplified in approximately 20% of breast cancers. HER2 inhibitors alone are not effective, and sensitizing agents will be necessary to move away from a reliance on heavily toxic chemotherapeutics. We recently demonstrated that the efficacy of HER2 inhibitors is mitigated by uniformly low levels of the myeloid cell leukemia 1 (MCL-1) endogenous inhibitor, NOXA. Emerging clinical data have demonstrated that clinically advanced cyclin-dependent kinase (CDK) inhibitors are effective MCL-1 inhibitors in patients, and, importantly, well tolerated. We, therefore, tested whether the CDK inhibitor, dinaciclib, could block MCL-1 in preclinical HER2-amplified breast cancer models and therefore sensitize these cancers to dual HER2/EGFR inhibitors neratinib and lapatinib, as well as to the novel selective HER2 inhibitor tucatinib. Indeed, we found dinaciclib suppresses MCL-1 RNA and is highly effective at sensitizing HER2 inhibitors both in vitro and in vivo. This combination was tolerable in vivo. Mechanistically, liberating the effector BCL-2 protein, BAK, from MCL-1 results in robust apoptosis. Thus, clinically advanced CDK inhibitors may effectively combine with HER2 inhibitors and present a chemotherapy-free therapeutic strategy in HER2-amplified breast cancer, which can be tested immediately in the clinic.

Regorafenib inhibits migration, invasion, and vasculogenic mimicry of hepatocellular carcinoma via targeting ID1-mediated EMT

Regorafenib is approved for patients with unresectable hepatocellular carcinoma (HCC) following sorafenib. However, the effect of regorafenib on HCC metastasis and its mechanism are poorly understood. Here, our data showed that regorafenib significantly restrained the migration, invasion and vasculogenic mimicry (VM) of HCC cells, and downregulated the expression of epithelial-to-mesenchymal transition (EMT)/VM-related molecules. Using RNA-seq and cellular thermal shift assays, we found that inhibitor of differentiation 1 (ID1) was a key target of regorafenib. In HCC tissues, the protein expression of ID1 was positively correlated with EMT and VM formation (CD34- /PAS+ ). Functionally, ID1 knockdown inhibited HCC cell migration, invasion, metastasis, and VM formation in vitro and in vivo, with upregulation of E-cadherin and downregulation of Snail and VE-cadherin. Moreover, Snail overexpression promoted the migration, invasion, and VM formation of ID1 knockdown cells. Snail knockdown reduced the migration, invasion, and VM formation of ID1 overexpression cells. Finally, regorafenib suppressed VM formation and decreased the expression of ID1, VE-cadherin and Snail in HCC PDX model. In conclusion, we manifested that regorafenib distinctly inhibited EMT in HCC cells via targeting ID1, leading to the suppression of cell migration, invasion and VM formation. These findings suggest that regorafenib may be developed as a suitable therapeutic agent for HCC metastasis.

OTUB1 Promotes Progression and Proliferation of Prostate Cancer via Deubiquitinating and Stabling Cyclin E1

Background: Prostate cancer (PCa) is currently the most common cancer among males worldwide. It has been reported that OTUB1 plays a critical role in a variety of tumors and is strongly related to tumor proliferation, migration, and clinical prognosis. The aim of this research is to investigate the regulatory effect of OTUB1 on PCa proliferation and the underlying mechanism. Methods: Using the TCGA database, we identified that OTUB1 was up-regulated in PCa, and observed severe functional changes in PC3 and C4-2 cells through overexpression or knock down OTUB1. Heterotopic tumors were implanted subcutaneously in nude mice and IHC staining was performed on tumor tissues. The relationship between OTUB1 and cyclin E1 was identified via Western blotting and immunoprecipitations assays. Results: We found that the expression of OTUB1 in PCa was significantly higher than that in Benign Prostatic Hyperplasia (BPH). Overexpression OTUB1 obviously promoted the proliferation and migration of PC3 and C4-2 cells via mediating the deubiquitinated Cyclin E1, while OTUB1 knockout has the opposite effect. The nude mice experiment further explained the above conclusions. We finally determined that OTUB1 promotes the proliferation and progression of PCa via deubiquitinating and stabling Cyclin E1. Conclusions: Our findings reveal the critical role of OTUB1 in PCa, and OTUB1 promotes the proliferation and progression of PCa via deubiquitinating and stabilizing Cyclin E1. Blocking OTUB1/Cyclin E1 axis or applying RO-3306 could significantly repress the occurrence and development of PCa. OTUB1/Cyclin E1 axis might provide a new and potential therapeutic target for PCa.

LncRNA TTN-AS1 intensifies sorafenib resistance in hepatocellular carcinoma by sponging miR-16-5p and upregulation of cyclin E1

Drug resistance has always been an important problem affecting the therapeutic effect of hepatocellular carcinoma (HCC). To investigate the potential role of lncRNA TTN-AS1 in HCC cells with sorafenib (SOR) resistance, and explore the underlying pathways, quantitative real time polymerase chain reaction (qRT-PCR) was used to test the expression of TTN-AS1 in HCC tissues and cells. Then, the expression of TTN-AS1 was down-regulated by shRNA, the activity changes, apoptosis and related protein expression in HCC cells with/without SOR treatment were observed in succession. Expression levels of the downstream target of TTN-AS1, miR-16-5p were studied by dual-luciferase binding assay, cell proliferation, and western blotting analysis. Nude mice models of human HCC with TTN-AS1 gene knockdown were established to observe the tumor growth. As the results revealed, TTN-AS1 silencing in HCC cells induced apoptosis by enhancing the sensitivity of cells to SOR, and the tumor in nude mice became smaller. The mechanism study showed that miR-16-5p was affected by TTN-AS1 sponge, up-regulated cyclin E1 expression, and regulated PTEN/Akt signaling pathway, thereby significantly alleviating the inhibition of apoptosis of HCC cells induced by TTN-AS1 gene. Collectively, our results provided TTN-AS1 as a potential therapeutic target for sorafenib resistance in HCC.

Long non-coding RNA ELDR enhances oral cancer growth by promoting ILF3-cyclin E1 signaling

Oral squamous cell carcinoma (OSCC) is the sixth most common cancer with a 5-year overall survival rate of 50%. Thus, there is a critical need to understand the disease process, and to identify improved therapeutic strategies. Previously, we found the long non-coding RNA (lncRNA) EGFR long non-coding downstream RNA (ELDR) induced in a mouse tongue cancer model; however, its functional role in human oral cancer remained unknown. Here, we show that ELDR is highly expressed in OSCC patient samples and in cell lines. Overexpression of ELDR in normal non-tumorigenic oral keratinocytes induces cell proliferation, colony formation, and PCNA expression. We also show that ELDR depletion reduces OSCC cell proliferation and PCNA expression. Proteomics data identifies the RNA binding protein ILF3 as an interacting partner of ELDR. We further show that the ELDR-ILF3 axis regulates Cyclin E1 expression and phosphorylation of the retinoblastoma (RB) protein. Intratumoral injection of ELDR-specific siRNA reduces OSCC and PDX tumor growth in mice. These findings provide molecular insight into the role of ELDR in oral cancer and demonstrate that targeting ELDR has promising therapeutic potential.

Development of Mcl-1 inhibitors for cancer therapy

The myeloid leukemia cell differentiation protein (Mcl-1) is an anti-apoptotic protein of the B-cell lymphoma 2 (Bcl-2) family, which regulates cellular apoptosis. Mcl-1 expression plays a key role in survival of cancer cells and therefore serves as a promising target in cancer therapy. Besides, its importance as a cancer target, various peptides and small-molecule inhibitors have been successfully designed and synthesized, yet no Mcl-1 inhibitor is approved for clinical use. However, recent development on the understanding of Mcl-1's role in key cellular processes in cancer and an upsurge of reports highlighting its association in various anticancer drug resistance supports the view that Mcl-1 is a key target in various cancers, especially hematological cancers. This review compiles structures of a variety of inhibitors of Mcl-1 reported to date. These include inhibitors based on a diverse range of heterocycles (e.g. indole, imidazole, thiophene, nicotinic acid, piperazine, triazine, thiazole, isoindoline), oligomers (terphenyl, quaterpyridine), polyphenol, phenalene, anthranilic acid, anthraquinone, macrocycles, natural products, and metal-based complexes. In addition, an effort has been made to summarize the structure activity relationships, based on a variety of assays, of some important classes of Mcl-1 inhibitors, giving affinities and selectivities for Mcl-1 compared to other Bcl-2 family members. A focus has been placed on categorizing the inhibitors based on their core frameworks (scaffolds) to appeal to the chemical biologist or medicinal chemist.

Targeted therapy for hepatocellular carcinoma

The last 3 years have seen the emergence of promising targeted therapies for the treatment of hepatocellular carcinoma (HCC). Sorafenib has been the mainstay of treatment for a decade and newer modalities were ineffective and did not confer any increased therapeutic benefit until the introduction of lenvatinib which was approved based on its non-inferiority to sorafenib. The subsequent success of regorafenib in HCC patients who progress on sorafenib treatment heralded a new era of second-line treatment and was quickly followed by ramucirumab, cabozantinib, and the most influential, immune checkpoint inhibitors (ICIs). Over the same period combination therapies, including anti-angiogenesis agents with ICIs, dual ICIs and targeted agents in conjunction with surgery or other loco-regional therapies, have been extensively investigated and have shown promise and provided the basis for exciting clinical trials. Work continues to develop additional novel therapeutic agents which could potentially augment the presently available options and understand the underlying mechanisms responsible for drug resistance, with the goal of improving the survival of patients with HCC.

MTHFD1L as a folate cycle enzyme correlates with prognostic outcome and its knockdown impairs cell invasive behaviors in osteosarcoma via mediating the AKT/mTOR pathway

Osteosarcoma (OS) is the most frequent primary malignancy initially in bone with multiple genomic aberrations. Methylenetetrahydrofolate dehydrogenase 1-like (MTHFD1L) is linked with the progression of diverse tumors. However, its function in OS is not understood completely. The expression pattern and prognostic significance of MTHFD1L in OS tissues were analyzed based on GEO database. The expression level of MTHFD1L in OS cell lines was explored by qRT-PCR. The cell proliferation, colony formation ability, invasion as well as migration in OS cells after MTHFD1L knockdown were determined using cell counting kit 8 (CCK-8) assay, colony formation and transwell methods. GSEA analysis was performed to predict the underlying mechanisms of MTHFD1L in OS development. Furthermore, the western blot was utilized to study the influence of MTHFD1L on AKT/mTOR pathway. Our results indicated that MTHFD1L expression was significantly up-regulated in OS tissues and cells compared with normal tissues and cells. High expression of MTHFD1L could lead to poor prognosis of OS patients. Cell proliferation, colony formation ability, migration and invasion were blocked because of reduced MTHFD1L in vitro. Moreover, cell cycle and AKT/mTOR pathway were all associated with MTHFD1L expression. In conclusion, the findings revealed that MTHFD1L might promote the development of OS via mediating cell cycle and AKT/mTOR pathway, indicating that MTHFD1L might act as a promising therapeutic target for OS treatment.

Role of cellular, molecular and tumor microenvironment in hepatocellular carcinoma: Possible targets and future directions in the regorafenib era

Hepatocellular carcinoma (HCC) remains as one of the major causes of cancer-related mortality, despite the recent development of new therapeutic options. Regorafenib, an oral multikinase inhibitor, is the first systemic therapy that has a survival benefit for patients with advanced HCC that have a poor response to sorafenib. Even though regorafenib has been approved by the FDA, the clinical trial for regorafenib treatment does not show significant improvement in overall survival. The impaired efficacy of regorafenib caused by various resistance mechanisms, including epithelial-mesenchymal transitions, inflammation, angiogenesis, hypoxia, oxidative stress, fibrosis and autophagy, still needs to be resolved. In this review, we provide insight on regorafenib microenvironmental, molecular and cellular mechanisms and interactions in HCC treatment. The aim of this review is to help physicians select patients that would obtain the maximal benefits from regorafenib in HCC therapy.

Regorafenib Alteration of the BCL-xL/MCL-1 Ratio Provides a Therapeutic Opportunity for BH3-Mimetics in Hepatocellular Carcinoma Models

BACKGROUND

The multikinase inhibitor regorafenib, approved as second-line treatment for hepatocellular carcinoma (HCC) after sorafenib failure, may induce mitochondrial damage. BH3-mimetics, inhibitors of specific BCL-2 proteins, are valuable drugs in cancer therapy to amplify mitochondrial-dependent cell death.

METHODS

In in vitro and in vivo HCC models, we tested regorafenib's effect on the BCL-2 network and the efficacy of BH3-mimetics on HCC treatment.

RESULTS

In hepatoma cell lines and Hep3B liver spheroids, regorafenib cytotoxicity was potentiated by BCL-xL siRNA transfection or pharmacological inhibition (A-1331852), while BCL-2 antagonism had no effect. Mitochondrial outer membrane permeabilization, cytochrome c release, and caspase-3 activation mediated A-1331852/regorafenib-induced cell death. In a patient-derived xenograft (PDX) HCC model, BCL-xL inhibition stimulated regorafenib activity, drastically decreasing tumor growth. Moreover, regorafenib-resistant HepG2 cells displayed increased BCL-xL and reduced MCL-1 expression, while A-1331852 reinstated regorafenib efficacy in vitro and in a xenograft mouse model. Interestingly, BCL-xL levels, associated with poor prognosis in liver and colorectal cancer, and the BCL-xL/MCL-1 ratio were detected as being increased in HCC patients.

CONCLUSION

Regorafenib primes tumor cells to BH3-mimetic-induced cell death, allowing BCL-xL inhibition with A-1331852 or other strategies based on BCL-xL degradation to enhance regorafenib efficacy, offering a novel approach for HCC treatment, particularly for tumors with an elevated BCL-xL/MCL-1 ratio.