Role of the receptor tyrosine kinase Axl in hepatocellular carcinoma and its clinical relevance

Discovery of a 1,6-naphthyridin-4-one-based AXL inhibitor with improved pharmacokinetics and enhanced in vivo antitumor efficacy

The receptor tyrosine kinase AXL has emerged as an attractive target in anticancer drug discovery. Herein, we described the discovery of a new series of 1,6-naphthyridin-4-one derivatives as potent AXL inhibitors. Starting from a low in vivo potency compound 9 which was previously reported by our group, we utilized structure-based drug design and scaffold hopping strategies to discover potent AXL inhibitors. The privileged compound 13c was a highly potent and orally bioavailable AXL inhibitor with an IC50 value of 3.2 ± 0.3 nM. Compound 13c exhibited significantly improved in vivo antitumor efficacy in AXL-driven tumor xenograft mice, causing tumor regression at well-tolerated dose, and demonstrated favorable pharmacokinetic properties (MRT = 16.5 h, AUC0-∞ = 59,815 ng h/mL) in Sprague-Dawley rats. These results suggest that 13c is a promising therapeutic candidate for AXL-targeting cancer treatment.

Altered expression of AXL receptor tyrosine kinase in gastrointestinal cancers: a promising therapeutic target

Gastrointestinal (GI) cancers that include all cancers of the digestive tract organs are generally associated with obesity, lack of exercising, smoking, poor diet, and heavy alcohol consumption. Treatment of GI cancers typically involves surgery followed by chemotherapy and/or radiation. Unfortunately, intrinsic or acquired resistance to these therapies underscore the need for more effective targeted therapies that have been proven in other malignancies. The aggressive features of GI cancers share distinct signaling pathways that are connected to each other by the overexpression and activation of AXL receptor tyrosine kinase. Several preclinical and clinical studies involving anti-AXL antibodies and small molecule AXL kinase inhibitors to test their efficacy in solid tumors, including GI cancers, have been recently carried out. Therefore, AXL may be a promising therapeutic target for overcoming the shortcomings of standard therapies in GI cancers.

Circular BANP knockdown inhibits the malignant progression of residual hepatocellular carcinoma after insufficient radiofrequency ablation

BACKGROUND

Circular RNAs (circRNAs) are endogenous non-coding RNAs, some of which have pathological roles. The current study aimed to explore the role of circRNA BTG3-associated nuclear protein (circ-BANP) binding with let-7f-5p and its regulation of the toll-like receptor 4 (TLR4)/signal transducer and activator of transcription 3 (STAT3) signaling pathway in residual hepatocellular carcinoma (HCC) after insufficient radiofrequency ablation (RFA).

METHODS

Circ-BANP, let-7f-5p, and TLR4 expressions in HCC samples were assessed using reverse transcription- quantitative polymerase chain reaction (RT-qPCR) and Western blotting. Bioinformatics prediction, RNA pull-down assay, and dual luciferase reporter gene assay were used to analyze the relationships among circ-BANP, let-7f-5p, and TLR4. Huh7 cells were used to generate an in vitro model of residual HCC, defined as Huh7-H cells, which were transfected with either a plasmid or the sequence of circ-BANP, let-7f-5p, or TLR4. Expression of circ-BANP, let-7f-5p, and TLR4 mRNA was determined by RT-qPCR. TLR4, STAT3, p-STAT3, vascular endothelial growth factor A, vascular endothelial growth factor receptor-2, and epithelial-mesenchymal transformation (EMT)-related factors proteins were determined by Western blotting. Cell proliferation was determined by cell counting kit-8 and 5-Ethynyl-2'-deoxyuridine (EdU) assay and cell migration and invasion by Transwell assay. Animal studies were performed by inducing xenograft tumors in nude mice.

RESULTS

Circ-BANP and TLR4 mRNAs were upregulated in HCC tissues (the fold change for circ-BANP was 1.958 and that for TLR4 was 1.736 relative to para-tumors) and expression further increased following insufficient RFA (fold change for circ- BANP was 2.407 and that of TLR4 was 2.224 relative to para-tumors). Expression of let-7f-5p showed an opposite tendency (fold change for let-7f-5p in HCC tissues was 0.491 and that in tumors after insufficient RFA was 0.300 relative to para-tumors). Competitive binding of circ-BANP to let-7f-5p was demonstrated and TLR4 was identified as a target of let-7f-5p (P < 0.01). Knockdown of circ-BANP or elevation of let-7f-5p expression inhibited the TLR4/STAT3 signaling pathway, proliferation, invasion, migration, angiogenesis, and EMT in Huh7 and Huh7-H cells (P < 0.01). The effects induced by circ-BANP knockdown were reversed by let-7f-5p inhibition. Overexpression of TLR4 reversed the impact of let-7f-5p upregulation on the cells (P < 0.01). Silencing of circ-BANP inhibited the in vivo growth of residual HCC cells after insufficient RFA (P < 0.01).

CONCLUSIONS

Knockdown of circ-BANP upregulated let-7f-5p to inhibit proliferation, migration, and EMT formation in residual HCC remaining after insufficient RFA. Effects occur via regulation of the TLR4/STAT3 signaling pathway.

Novel FLT3/AURK multikinase inhibitor is efficacious against sorafenib-refractory and sorafenib-resistant hepatocellular carcinoma

Background

Hepatocellular carcinoma (HCC) is the sixth most common type of cancer and has a high mortality rate worldwide. Sorafenib is the only systemic treatment demonstrating a statistically significant but modest overall survival benefit. We previously have identified the aurora kinases (AURKs) and FMS-like tyrosine kinase 3 (FLT3) multikinase inhibitor DBPR114 exhibiting broad spectrum anti-tumor effects in both leukemia and solid tumors. The purpose of this study was to evaluate the therapeutic potential of DBPR114 in the treatment of advanced HCC.

Methods

Human HCC cell lines with histopathology/genetic background similar to human HCC tumors were used for in vitro and in vivo studies. Human umbilical vein endothelial cells (HUVEC) were used to evaluate the drug effect on endothelial tube formation. Western blotting, immunohistochemical staining, and mRNA sequencing were employed to investigate the mechanisms of drug action. Xenograft models of sorafenib-refractory and sorafenib-acquired resistant HCC were used to evaluate the tumor response to DBPR114.

Results

DBPR114 was active against HCC tumor cell proliferation independent of p53 alteration status and tumor grade in vitro. DBPR114-mediated growth inhibition in HCC cells was associated with apoptosis induction, cell cycle arrest, and polyploidy formation. Further analysis indicated that DBPR114 reduced the phosphorylation levels of AURKs and its substrate histone H3. Moreover, the levels of several active-state receptor tyrosine kinases were downregulated by DBPR114, verifying the mechanisms of DBPR114 action as a multikinase inhibitor in HCC cells. DBPR114 also exhibited anti-angiogenic effect, as demonstrated by inhibiting tumor formation in HUVEC cells. In vivo, DBPR114 induced statistically significant tumor growth inhibition compared with the vehicle control in multiple HCC tumor xenograft models. Histologic analysis revealed that the DBPR114 treatment reduced cell proliferation, and induced apoptotic cell death and multinucleated cell formation. Consistent with the histological findings, gene expression analysis revealed that DBPR114-modulated genes were mostly related to the G2/M checkpoint and mitotic spindle assembly. DBPR114 was efficacious against sorafenib-intrinsic and -acquired resistant HCC tumors. Notably, DBPR114 significantly delayed posttreatment tumor regrowth and prolonged survival compared with the regorafenib group.

Conclusion

Our results indicated that targeting AURK signaling could be a new effective molecular-targeted agent in the treatment of patients with HCC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12929-022-00788-0.

Circular BANP knockdown inhibits the malignant progression of residual hepatocellular carcinoma after insufficient radiofrequency ablation

BACKGROUND

Circular RNAs (circRNAs) are endogenous non-coding RNAs, some of which have pathological roles. The current study aimed to explore the role of circRNA BTG3-associated nuclear protein (circ-BANP) binding with let-7f-5p and its regulation of the toll-like receptor 4 (TLR4)/signal transducer and activator of transcription 3 (STAT3) signaling pathway in residual hepatocellular carcinoma (HCC) after insufficient radiofrequency ablation (RFA).

METHODS

Circ-BANP, let-7f-5p, and TLR4 expressions in HCC samples were assessed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and Western blotting. Bioinformatics prediction, RNA pull-down assay, and dual luciferase reporter gene assay were used to analyze the relationships among circ-BANP, let-7f-5p, and TLR4. Huh7 cells were used to generate an in vitro model of residual HCC, defined as Huh7-H cells, which were transfected with either a plasmid or the sequence of circ-BANP, let-7f-5p, or TLR4. Expression of circ-BANP, let-7f-5p, and TLR4 mRNA was determined by RT-qPCR. TLR4, STAT3, p-STAT3, vascular endothelial growth factor A, vascular endothelial growth factor receptor-2, and epithelial-mesenchymal transformation (EMT)-related factors proteins were determined by Western blotting. Cell proliferation was determined by cell counting kit-8 and 5-Ethynyl-2'-deoxyuridine (EdU) assay and cell migration and invasion by Transwell assay. Animal studies were performed by inducing xenograft tumors in nude mice.

RESULTS

Circ-BANP and TLR4 mRNAs were upregulated in HCC tissues (the fold change for circ-BANP was 1.958 and that for TLR4 was 1.736 relative to para-tumors) and expression further increased following insufficient RFA (fold change for circ-BANP was 2.407 and that of TLR4 was 2.224 relative to para-tumors). Expression of let-7f-5p showed an opposite tendency (fold change for let-7f-5p in HCC tissues was 0.491 and that in tumors after insufficient RFA was 0.300 relative to para-tumors). Competitive binding of circ-BANP to let-7f-5p was demonstrated and TLR4 was identified as a target of let-7f-5p (P < 0.01). Knockdown of circ-BANP or elevation of let-7f-5p expression inhibited the TLR4/STAT3 signaling pathway, proliferation, invasion, migration, angiogenesis, and EMT in Huh7 and Huh7-H cells (P < 0.01). The effects induced by circ-BANP knockdown were reversed by let-7f-5p inhibition. Overexpression of TLR4 reversed the impact of let-7f-5p upregulation on the cells (P < 0.01). Silencing of circ-BANP inhibited the in vivo growth of residual HCC cells after insufficient RFA (P < 0.01).

CONCLUSIONS

Knockdown of circ-BANP upregulated let-7f-5p to inhibit proliferation, migration, and EMT formation in residual HCC remaining after insufficient RFA. Effects occur via regulation of the TLR4/STAT3 signaling pathway.

Exosomes secreted by M2 macrophages promote cancer stemness of hepatocellular carcinoma via the miR-27a-3p/TXNIP pathways

OBJECTIVE

Accumulating evidence has suggested that microRNAs (miRNAs) derived from M2 macrophage-derived exosomes (M2 exosomes) can regulate the progression of hepatocellular carcinoma (HCC). Nevertheless, the effect of miR-27a-3p derived from M2 exosomes on HCC has not been reported. We aim to explore the role of M2 exosomal miR-27a-3p in the cancer stemness of HCC via regulating thioredoxin-interacting protein (TXNIP).

METHODS

Exosomes were extracted from transfected M2 macrophages and were then co-cultured with HCC cells. Expression of miR-27a-3p and TXNIP, stemness, proliferation, drug resistance, migration, invasion and in vivo tumorigenicity of HCC cells were determined to assess the role of M2 exosomal miR-27a-3p in HCC. The binding relationship between miR-27a-3p and TXNIP was detected.

RESULTS

MiR-27a-3p was upregulated and TXNIP was downregulated in HCC cells, and M2 exosomes further upregulated miR-27a-3p. The upregulated M2 exosomal miR-27a-3p promoted stemness, proliferation, drug resistance, migration, invasion and in vivo tumorigenicity of HCC cells. TXNIP was confirmed as a target gene of miR-27a-3p.

CONCLUSION

M2 macrophages-derived exosomal miR-27a-3p promotes cancer stemness of HCC via downregulating TXNIP.

Second-line cabozantinib after sorafenib treatment for advanced hepatocellular carcinoma: a subgroup analysis of the phase 3 CELESTIAL trial

Objective

In the phase 3 CELESTIAL trial, cabozantinib improved overall survival (OS) and progression-free survival (PFS) compared with placebo in patients with previously treated advanced hepatocellular carcinoma (HCC). This subgroup analysis evaluated cabozantinib in patients who had received sorafenib as the only prior systemic therapy.

Methods

CELESTIAL randomised (2:1) patients with advanced HCC and Child–Pugh class A liver function to treatment with cabozantinib (60 mg daily) or placebo. Eligibility required prior treatment with sorafenib, and patients could have received ≤2 prior systemic regimens. The primary endpoint was OS. Outcomes in patients who had received sorafenib as the only prior therapy were analysed by duration of prior sorafenib (<3 months, 3 to <6 months and ≥6 months).

Results

Of patients who had received only prior sorafenib, 331 were randomised to cabozantinib and 164 to placebo; 136 patients had received sorafenib for <3 months, 141 for 3 to <6 months and 217 for ≥6 months. Cabozantinib improved OS relative to placebo in the overall second-line population who had received only prior sorafenib (median 11.3 vs 7.2 months; HR=0.70, 95% CI 0.55 to 0.88). This improvement was maintained in analyses by prior sorafenib duration with longer duration generally corresponding to longer median OS—median OS 8.9 vs 6.9 months (HR=0.72, 95% CI 0.47 to 1.10) for prior sorafenib <3 months, 11.5 vs 6.5 months (HR=0.65, 95% CI 0.43 to 1.00) for 3 to <6 months and 12.3 vs 9.2 months (HR=0.82, 95% CI 0.58 to 1.16) for ≥6 months. Cabozantinib also improved PFS in all duration subgroups. Safety data were consistent with the overall study population.

Conclusion

Cabozantinib improved efficacy outcomes versus placebo in the second-line population who had received only prior sorafenib irrespective of duration of prior sorafenib treatment, further supporting the utility of cabozantinib in the evolving treatment landscape of HCC.

Clinical trial number

NCT01908426.

Discovery of pyrrolo[2,3-d]pyrimidine derivatives as potent Axl inhibitors: Design, synthesis and biological evaluation

Axl has emerged as an attractive target for cancer therapy due to its strong correlation with tumor growth, metastasis, poor survival, and drug resistance. Herein, we report the design, synthesis and structure-activity relationship (SAR) investigation of a series of pyrrolo[2,3-d]pyrimidine derivatives as new Axl inhibitors. Among them, the most promising compound 13b showed high enzymatic and cellular Axl potencies. Furthermore, 13b possessed preferable pharmacokinetic properties and displayed promising therapeutic effect in BaF3/TEL-Axl xenograft tumor model. Compound 13b may serve as a lead compound for new antitumor drug discovery.

ADAMTSL5 is an epigenetically activated gene underlying tumorigenesis and drug resistance in hepatocellular carcinoma

BACKGROUND & AIMS

The tumour microenvironment shapes tumour growth through cellular communications that include both direct interactions and secreted factors. The aim of this study was to characterize the impact of the secreted glycoprotein ADAMTSL5, whose role in cancer has not been previously investigated, on hepatocellular carcinoma (HCC).

METHODS

ADAMTSL5 methylation status was evaluated through bisulfite sequencing, and publicly available data analysis. ADAMTSL5 RNA and protein expression were assessed in mouse models and HCC patient samples and compared to data from published datasets. Functional studies, including association of ADAMTSL5 depletion with responsiveness to clinically relevant drugs, were performed in cellular and in vivo models. Molecular alterations associated with ADAMTSL5 targeting were determined using proteomics, biochemistry, and reverse-transcription quantitative PCR.

RESULTS

Methylome analysis revealed hypermethylated gene body CpG islands at the ADAMTSL5 locus in both mouse and human HCC, correlating with higher ADAMTSL5 expression. ADAMTSL5 targeting interfered with tumorigenic properties of HCC cells in vitro and in vivo, whereas ADAMTSL5 overexpression conferred tumorigenicity to pre-tumoural hepatocytes sensitized to transformation by a modest level of MET receptor expression. Mechanistically, ADAMTSL5 abrogation led to a reduction of several oncogenic inputs relevant to HCC, including reduced expression and/or phosphorylation levels of receptor tyrosine kinases MET, EGFR, PDGFRβ, IGF1Rβ, or FGFR4. This phenotype was associated with significantly increased sensitivity of HCC cells to clinically relevant drugs, namely sorafenib, lenvatinib, and regorafenib. Moreover, ADAMTSL5 depletion drastically increased expression of AXL, accompanied by a sensitization to bemcentinib.

CONCLUSIONS

Our results point to a role for ADAMTSL5 in maintaining the function of key oncogenic signalling pathways, suggesting that it may act as a master regulator of tumorigenicity and drug resistance in HCC.

LAY SUMMARY

The environment of cancer cells has profound effects on establishment, progression, and response of a tumour to treatment. Herein, we show that ADAMTSL5, a protein secreted by liver cancer cells and overlooked in cancer so far, is increased in this tumour type, is necessary for tumour formation and supports drug resistance. Adamtsl5 removal conferred sensitivity of liver cancer cells to drugs used in current treatment. This suggests ADAMTSL5 as a potential marker in liver cancer as well as a possible drug target.

Drug Discovery in Liver Disease Using Kinome Profiling

The liver is one of the most important organs, playing critical roles in maintaining biochemical homeostasis. Accordingly, disease of the liver is often debilitating and responsible for untold human misery. As biochemical nexus, with kinases being master regulators of cellular biochemistry, targeting kinase enzymes is an obvious avenue for treating liver disease. Development of such therapy, however, is hampered by the technical difficulty of obtaining comprehensive insight into hepatic kinase activity, a problem further compounded by the often unique aspects of hepatic kinase activities, which makes extrapolations from other systems difficult. This consideration prompted us to review the current state of the art with respect to kinome profiling approaches towards the hepatic kinome. We observe that currently four different approaches are available, all showing significant promise. Hence we postulate that insight into the hepatic kinome will quickly increase, leading to rational kinase-targeted therapy for different liver diseases.

Management of Adverse Events Associated with Cabozantinib Treatment in Patients with Advanced Hepatocellular Carcinoma

Cabozantinib is an oral multikinase inhibitor whose targets include vascular endothelial growth factor receptors, MET, and the TAM family of kinases (TYRO3, AXL, MER). Cabozantinib is approved for patients with advanced hepatocellular carcinoma who have been previously treated with sorafenib, based on improved overall survival and progression-free survival relative to placebo in the phase III CELESTIAL study. During CELESTIAL, the most common adverse events (AEs) experienced by patients receiving cabozantinib included palmar-plantar erythrodysesthesia, fatigue, gastrointestinal-related events, and hypertension. These AEs can significantly impact treatment tolerability and patient quality of life. However, AEs can be effectively managed with supportive care and dose modifications. During CELESTIAL, more than half of the patients receiving cabozantinib required a dose reduction, while the rate of treatment discontinuation due to AEs was low. Here, we review the safety profile of cabozantinib and provide guidance on the prevention and management of the more common AEs, based on current evidence from the literature as well as our clinical experience. We consider the specific challenges faced by clinicians in treating this patient population and discuss factors that may affect exposure and tolerability to cabozantinib.