The AXL receptor tyrosine kinase is associated with adverse prognosis and distant metastasis in esophageal squamous cell carcinoma

AXL - a new player in resistance to HER2 blockade

HER2 is a driver in solid tumors, mainly breast, oesophageal and gastric cancer, through activation of oncogenic signaling pathways such as PI3K or MAPK. HER2 overexpression associates with aggressive disease and poor prognosis. Despite targeted anti-HER2 therapy has improved outcomes and is the current standard of care, resistance emerge in some patients, requiring additional therapeutic strategies. Several mechanisms, including the upregulation of receptors tyrosine kinases such as AXL, are involved in resistance. AXL signaling leads to cancer cell proliferation, survival, migration, invasion and angiogenesis and correlates with poor prognosis. In addition, AXL overexpression accompanied by a mesenchymal phenotype result in resistance to chemotherapy and targeted therapies. Preclinical studies show that AXL drives anti-HER2 resistance and metastasis through dimerization with HER2 and activation of downstream pathways in breast cancer. Moreover, AXL inhibition restores response to HER2 blockade in vitro and in vivo. Limited data in gastric and oesophageal cancer also support these evidences. Furthermore, AXL shows a strong value as a prognostic and predictive biomarker in HER2+ breast cancer patients, adding a remarkable translational relevance. Therefore, current studies enforce the potential of co-targeting AXL and HER2 to overcome resistance and supports the use of AXL inhibitors in the clinic.

Structure-based drug discovery of novel fused-pyrazolone carboxamide derivatives as potent and selective AXL inhibitors

As a novel and promising antitumor target, AXL plays an important role in tumor growth, metastasis, immunosuppression and drug resistance of various malignancies, which has attracted extensive research interest in recent years. In this study, by employing the structure-based drug design and bioisosterism strategies, we designed and synthesized in total 54 novel AXL inhibitors featuring a fused-pyrazolone carboxamide scaffold, of which up to 20 compounds exhibited excellent AXL kinase and BaF3/TEL-AXL cell viability inhibitions. Notably, compound 59 showed a desirable AXL kinase inhibitory activity (IC50: 3.5 nmol/L) as well as good kinase selectivity, and it effectively blocked the cellular AXL signaling. In turn, compound 59 could potently inhibit BaF3/TEL-AXL cell viability (IC50: 1.5 nmol/L) and significantly suppress GAS6/AXL-mediated cancer cell invasion, migration and wound healing at the nanomolar level. More importantly, compound 59 oral administration showed good pharmacokinetic profile and in vivo antitumor efficiency, in which we observed significant AXL phosphorylation suppression, and its antitumor efficacy at 20 mg/kg (qd) was comparable to that of BGB324 at 50 mg/kg (bid), the most advanced AXL inhibitor. Taken together, this work provided a valuable lead compound as a potential AXL inhibitor for the further antitumor drug development.

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.

Gas6/AXL pathway: immunological landscape and therapeutic potential

Cancer is a disease with ecological and evolutionary unity, which seriously affects the survival and quality of human beings. Currently, many reports have suggested Gas6 plays an important role in cancer. Binding of gas6 to TAM receptors is associated with the carcinogenetic mechanisms of multiple malignancies, such as in breast cancer, chronic lymphocytic leukemia, non-small cell lung cancer, melanoma, prostate cancer, etc., and shortened overall survival. It is accepted that the Gas6/TAM pathway can promote the malignant transformation of various types of cancer cells. Gas6 has the highest affinity for Axl, an important member of the TAM receptor family. Knockdown of the TAM receptors Axl significantly affects cell cycle progression in tumor cells. Interestingly, Gas6 also has an essential function in the tumor microenvironment. The Gas6/AXL pathway regulates angiogenesis, immune-related molecular markers and the secretion of certain cytokines in the tumor microenvironment, and also modulates the functions of a variety of immune cells. In addition, evidence suggests that the Gas6/AXL pathway is involved in tumor therapy resistance. Recently, multiple studies have begun to explore in depth the importance of the Gas6/AXL pathway as a potential tumor therapeutic target as well as its broad promise in immunotherapy; therefore, a timely review of the characteristics of the Gas6/AXL pathway and its value in tumor treatment strategies is warranted. This comprehensive review assessed the roles of Gas6 and AXL receptors and their associated pathways in carcinogenesis and cancer progression, summarized the impact of Gas6/AXL on the tumor microenvironment, and highlighted the recent research progress on the relationship between Gas6/AXL and cancer drug resistance.

NAT10-mediated AXL mRNA N4-acetylcytidine modification promotes pancreatic carcinoma progression

Although the patient's survival time in various cancers has significantly increased in recent decades, the overall 5-year survival rate of pancreatic ductal adenocarcinoma (PDAC) has remained virtually unchanged due to rapid progression and metastasis. While N-acetyltransferase 10 (NAT10) has been identified as a regulator of mRNA acetylation in many malignancies, its role in PDAC remains unclear. Here, we found that NAT10 mRNA and protein levels were upregulated in PDAC tissues. Increased NAT10 protein expression was significantly correlated with poor prognosis in PDAC patients. Through our experiments, we demonstrated that NAT10 acted as an oncogene to promote PDAC tumorigenesis and metastasis in vitro and in vivo. Mechanistically, NAT10 exerts its oncogenic effects by promoting mRNA stability of receptor tyrosine kinase AXL in an ac4C-dependent manner leading to increased AXL expression and further promoting PDAC cell proliferation and metastasis. Together, our findings highlight the critical of NAT10 in PDAC progression and reveal a novel epigenetic mechanism by which modified mRNA acetylation promotes PDAC metastasis.

AXL Inhibitors: Status of Clinical Development

PURPOSE OF REVIEW

The AXL signaling pathway is associated with tumor growth as well as poor prognosis in cancer. Here, we highlight recent strategies for targeting AXL in the treatment of solid and hematological malignancies.

RECENT FINDINGS

AXL is a key player in survival, metastasis, and therapeutic resistance in many cancers. A range of AXL-targeted therapies, including tyrosine kinase inhibitors, monoclonal antibodies, antibody-drug conjugates, and soluble receptors, have entered clinical development. Notably, AXL inhibitors in combination with immune checkpoint inhibitors demonstrate early promise; however, further understanding of predictive biomarkers and treatment sequencing is necessary. Based on its role in tumor growth and drug resistance, AXL represents a promising therapeutic target in oncology. Results from ongoing clinical trials will provide valuable insights into the role of AXL inhibitors, both as single agents and in combination with other therapies.

Potent molecular-targeted therapies for advanced esophageal squamous cell carcinoma

Esophageal cancer (EC) remains a public health concern with a high mortality and disease burden worldwide. Esophageal squamous cell carcinoma (ESCC) is a predominant histological subtype of EC that has unique etiology, molecular profiles, and clinicopathological features. Although systemic chemotherapy, including cytotoxic agents and immune checkpoint inhibitors, is the main therapeutic option for recurrent or metastatic ESCC patients, the clinical benefits are limited with poor prognosis. Personalized molecular-targeted therapies have been hampered due to the lack of robust treatment efficacy in clinical trials. Therefore, there is an urgent need to develop effective therapeutic strategies. In this review, we summarize the molecular profiles of ESCC based on the findings of pivotal comprehensive molecular analyses, highlighting potent therapeutic targets for establishing future precision medicine for ESCC patients, with the most recent results of clinical trials.

Phase I Study Evaluating Glesatinib (MGCD265), An Inhibitor of MET and AXL, in Patients with Non-small Cell Lung Cancer and Other Advanced Solid Tumors

BACKGROUND

Heightened signaling by mesenchymal epithelial transition factor (MET) is implicated in tumorigenesis. Glesatinib is an investigational, oral inhibitor of MET and AXL.

OBJECTIVE

This phase I study determined the maximum tolerated dose (MTD), recommended phase II dose (RP2D), and safety profile of glesatinib in patients with advanced or unresectable solid tumors. Antitumor activity and pharmacokinetics (PK) were secondary objectives.

PATIENTS AND METHODS

Four formulations of glesatinib glycolate salt (capsule, unmicronized, micronized, and micronized version 2 [V2] tablets) and two free-base formulations (free-base suspension [FBS] capsule and spray-dried dispersion [SDD] tablet), developed to enhance drug exposure and optimize manufacturing processes, were evaluated in patients with genetically unselected advanced/unresectable solid tumors. MTD, based on dose-limiting toxicities (DLTs) observed during the first 21-day treatment cycle, was further evaluated in dose-expansion cohorts comprising patients with overexpression of MET and/or AXL, MET/AXL amplification, MET-activating mutations, or MET/AXL rearrangements for confirmation as the RP2D.

RESULTS

Glesatinib was evaluated across 27 dose-escalation cohorts (n = 108). Due to suboptimal exposure with glesatinib glycolate salt formulations in the initial cohorts, investigations subsequently focused on the FBS capsule and SDD tablet; for these formulations, MTD was identified as 1050 mg twice daily and 750 mg twice daily, respectively. An additional 71 patients received glesatinib in the FBS and SDD dose-expansion cohorts. At MTDs, the most frequent treatment-related adverse events were diarrhea (FBS, 83.3%; SDD, 75.0%), nausea (57.1%, 30.6%), vomiting (45.2%, 25.0%), increased alanine aminotransferase (45.2%, 30.6%), and increased aspartate aminotransferase (47.6%, 27.8%). Exploratory pharmacodynamic analyses indicated target engagement and inhibition of MET by glesatinib. Antitumor activity was observed with glesatinib FBS 1050 mg twice daily and SDD 750 mg twice daily in tumors harboring MET/AXL alteration or aberrant protein expression, particularly in patients with non--small cell lung cancer (NSCLC). In patients with NSCLC, the objective response rate was 25.9% in those with MET/AXL mutation or amplification and 30.0% in a subset with MET-activating mutations. All six partial responses occurred in patients with tumors carrying MET exon 14 deletion mutations.

CONCLUSIONS

The safety profile of single-agent glesatinib was acceptable. SDD 750 mg twice daily was selected as the preferred glesatinib formulation and dose based on clinical activity, safety, and PK data. Observations from this study led to initiation of a phase II study of glesatinib in patients with NSCLC stratified by type of MET alteration (NCT02544633).

CLINICAL TRIALS REGISTRATION

ClinicalTrials.gov NCT00697632; June 2008.

Phase I Study of Glesatinib (MGCD256) in Combination with Erlotinib or Docetaxel in Patients with Advanced Solid Tumors

BACKGROUND

Oncogenic drivers in solid tumors include aberrant activation of mesenchymal epithelial transition factor (MET) and AXL.

OBJECTIVE

This study investigated the safety and antitumor activity of glesatinib, a multitargeted receptor tyrosine kinase inhibitor that inhibits MET and AXL at clinically relevant doses, in combination with erlotinib or docetaxel.

PATIENTS AND METHODS

The phase I portion of this open-label, multicenter study included two parallel arms in which ascending doses of oral glesatinib (starting dose 96 mg/m²) were administered with erlotinib or docetaxel (starting doses 100 mg once daily and 50 mg/m², respectively) using a modified 3 + 3 design. Maximum tolerated dose (MTD) was based on dose-limiting toxicities (DLTs) during the first 21-day treatment cycle. Enrollment focused on patients with solid tumor types typically associated with MET aberration and/or AXL overexpression. The primary objective was to determine the safety profile of the treatment combinations. Antitumor activity and pharmacokinetics (PK) were also assessed.

RESULTS

Ten dose levels of glesatinib across three glycolate formulations (unmicronized, micronized, or micronized version 2 [V2] tablets) available during the course of the study were investigated in 14 dose-escalation cohorts (n = 126). MTDs of unmicronized glesatinib plus erlotinib or docetaxel, and micronized glesatinib plus erlotinib were not reached. Micronized glesatinib 96 mg/m² plus docetaxel exceeded the MTD. Further dosing focused on glesatinib micronized V2: maximum administered dose (MAD) was 700 mg twice daily with erlotinib 150 mg once daily or docetaxel 75 mg/m² every 3 weeks. DLTs, acceptable at lower glesatinib (micronized V2) dose levels, occurred in two of five and two of six patients at the MADs of glesatinib + erlotinib and glesatinib + docetaxel, respectively. Across all cohorts, the most frequent treatment-related adverse events were diarrhea (glesatinib + erlotinib: 84.1%; glesatinib + docetaxel: 45.6%), fatigue (46.4%, 70.4%), and nausea (30.4%, 35.1%). The objective response rate was 1.8% and 12.0% in all glesatinib + erlotinib and glesatinib + docetaxel cohorts, respectively.

CONCLUSIONS

The safety profile of glesatinib plus erlotinib or docetaxel was acceptable and there were no PK interactions. MADs of glesatinib 700 mg twice daily (micronized V2) with erlotinib 150 mg once daily or docetaxel 75 mg/m² every 3 weeks exceeded the MTD by a small margin. Modest signals of efficacy were observed with these treatment combinations in non-genetically selected patients with advanced solid tumors.

CLINICAL TRIALS REGISTRATION

ClinicalTrials.gov NCT00975767; 11 September 2009.

Association of High Expression of Mitochondrial Fission Regulator 2 with Poor Survival of Patients with Esophageal Squamous Cell Carcinoma

Mitochondrial fission regulator 2 (MTFR2) is associated with mitochondrial fission, while few studies have assessed the associations between MTFR2 expression and clinical characteristics or prognosis of esophageal squamous cell carcinoma (ESCC). In this study, we compared the expression of MTFR2 in 6 ESCC tumors and relative normal tissues by immunohistochemistry (IHC). To assess the effect of MTFR2 expression on clinicopathologic characteristics and survival, 115 paraffin embedded ESCC tissue samples were assessed by IHC staining. Furthermore, the association between clinicopathological properties and MTFR2 expression in patients with ESCC was examined. The survival analysis was performed using the Cox regression models. We found that MTFR2 expression was significantly increased in ESCC tumors compared with normal esophageal epithelial cells. IHC analysis of 115 paraffin embedded ESCC tumor specimens of the patients showed that the expression of MTFR2 was significantly associated with clinical stage (P < 0.001), tumor classification (P < 0.001), histological grade (P < 0.001), and other clinicopathological characteristics. Both univariate and multivariate analyses showed that MTFR2 expression was inversely correlated with the survival of ESCC patients. In conclusion, the expression of MTFR2 is significantly associated with clinicopathologic characteristics and prognosis of ESCC. Thus, MTFR2 expression could serve as a potentially important prognostic biomarker and clinical target for patients with ESCC.

Therapeutic Targeting of the Gas6/Axl Signaling Pathway in Cancer

Many signaling pathways are dysregulated in cancer cells and the host tumor microenvironment. Aberrant receptor tyrosine kinase (RTK) pathways promote cancer development, progression, and metastasis. Hence, numerous therapeutic interventions targeting RTKs have been actively pursued. Axl is an RTK that belongs to the Tyro3, Axl, MerTK (TAM) subfamily. Axl binds to a high affinity ligand growth arrest specific 6 (Gas6) that belongs to the vitamin K-dependent family of proteins. The Gas6/Axl signaling pathway has been implicated to promote progression, metastasis, immune evasion, and therapeutic resistance in many cancer types. Therapeutic agents targeting Gas6 and Axl have been developed, and promising results have been observed in both preclinical and clinical settings when such agents are used alone or in combination therapy. This review examines the current state of therapeutics targeting the Gas6/Axl pathway in cancer and discusses Gas6- and Axl-targeting agents that have been evaluated preclinically and clinically.

Inhibition of the Axl pathway impairs breast and prostate cancer metastasis to the bones and bone remodeling

Approximately 90% of cancer-related deaths result from cancer metastasis. In prostate and breast cancers, bone is the most common site of cancer cell dissemination. Key steps in the metastatic cascade are promoted through upregulation of critical cell signaling pathways in neoplastic cells. The present study assessed the role of the receptor tyrosine kinase Axl in prostate and breast cancer cell metastasis to bones using (i) Axl knockdown neoplastic cells and osteoclast progenitor cells in vitro, (ii) intracardiac injection of Axl knockdown tumor cells in vivo, and (iii) selective Axl inhibitor BGB324. Axl inhibition in neoplastic cells significantly decreased their metastatic potential, and suppression of Axl signaling in osteoclast precursor cells also reduced the formation of mature osteoclasts. In vivo, Axl knockdown in prostate and breast cancer cells significantly suppressed the formation and progression of bone metastases. Hence, therapeutic targeting of Axl may impair tumor metastasis to the bones through neoplastic and host cell signaling axes.

The Role of the Receptor Tyrosine Kinase Axl in Carcinogenesis and Development of Therapeutic Resistance: An Overview of Molecular Mechanisms and Future Applications

Resistance to chemotherapeutic agents by cancer cells has remained a major obstacle in the successful treatment of various cancers. Numerous factors such as DNA damage repair, cell death inhibition, epithelial-mesenchymal transition, and evasion of apoptosis have all been implicated in the promotion of chemoresistance. The receptor tyrosine kinase Axl, a member of the TAM family (which includes TYRO3 and MER), plays an important role in the regulation of cellular processes such as proliferation, motility, survival, and immunologic response. The overexpression of Axl is reported in several solid and hematological malignancies, including non-small cell lung, prostate, breast, liver and gastric cancers, and acute myeloid leukaemia. The overexpression of Axl is associated with poor prognosis and the development of resistance to therapy. Reports show that Axl overexpression confers drug resistance in lung cancer and advances the emergence of tolerant cells. Axl is, therefore, an important candidate as a prognostic biomarker and target for anticancer therapies. In this review, we discuss the consequence of Axl upregulation in cancers, provide evidence for its role in cancer progression and the development of drug resistance. We will also discuss the therapeutic potential of Axl in the treatment of cancer.

The genetic effect and molecular function of the SOCS5 in the prognosis of esophageal squamous cell carcinoma

Expression of cytokines and growth factors have been shown to be highly correlated with the prognosis of esophageal squamous cell carcinoma (ESCC), a deadly disease with poor prognosis. The suppressor of cytokine signaling (SOCS) family of proteins are key factors in regulating cytokines and growth factors. Yet the role of the SOCS proteins in ESCC is hardly investigated. We currently investigated the prognostic role of SOCS5 in ESCC. We analyzed the prognostic effects of 16 single nucleotide polymorphisms (SNPs) within the SOCS genes in 632 ESCC patients. We repeatedly observed that the 3 SNPs in SOCS5, SOCS5:rs3814039, SOCS5:rs3738890, and SOCS5: rs3768720, were significantly correlated with both overall (OS) and progression-free survival (PFS) of ESCC patients (rs3814039, p=0.032 for OS and p=0.009 for PFS; rs3738890, p=0.016 for OS, and p=0.008 for PFS; rs3768720, p=0.005 for OS and p=0.002 for PFS). SOCS5: rs3768720 was also significantly associated with distant metastasis (Ptrend=0.028). The luciferase assay revealed that SOCS5:rs3814039 and SOCS5: rs3768720 might influence the prognosis by regulating SOCS5 expression. Functional analysis demonstrated SOCS5 was able to regulate epidermal growth factor receptor (EGFR) expression and migration activity of ESCC cells. Furthermore, Patients with strong SOCS5 in normal tissues exhibited significantly better PFS (P=0.049) and reduced risk of distant metastasis (P=0.004) compared to those with weak SOCS5 expression. Overall, our study demonstrates the novel function of SOCS5 in ESCC prognosis. The genetic polymorphisms and expression of SOCS5 could serve as a novel therapeutic biomarker for improving the prognosis of ESCC.

Therapeutic aspects of the Axl/Gas6 molecular system

Axl receptor tyrosine kinase (RTK) and its ligand, growth arrest-specific protein 6 (Gas6), are involved in several biological functions and participate in the development and progression of a range of malignancies and autoimmune disorders. In this review, we present this molecular system from a drug discovery perspective, highlighting its therapeutic implications and challenges that need to be addressed. We provide an update on Axl/Gas6 axis biology, exploring its role in fields ranging from angiogenesis, cancer development and metastasis, immune response and inflammation to viral infection. Finally, we summarize the molecules that have been developed to date to target the Axl/Gas6 molecular system for therapeutic and diagnostic applications.

Pharmaceutical inhibition of AXL suppresses tumor growth and invasion of esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a common type of cancer in a number of regions of the world, including East Asia, South Africa and Iran. It is often associated with poor prognosis rates. Tyrosine-protein kinase receptor UFO (AXL) is overexpressed in a subset of ESCC tumors, therefore the present study aimed to determine the effect of R428, a selective inhibitor of AXL, on ESCC tumor cells. TE1 and KYSE150 cell lines were used as models to investigate the effects of R428 treatment. The proliferative rate of the tumor cells was analyzed using MTT and colony formation assays. In addition, cell migration and invasion rates were analyzed using wound healing and Matrigel assays, respectively. The expression levels of matrix metalloproteinase (MMP)2 and MMP9, and the activation of protein kinase B (AKT), extracellular signal-regulated kinase (ERK) and AXL signaling were analyzed using gelatin zymography and western blotting. The results revealed that R428 inhibited the proliferative and invasive abilities of both cell lines. Furthermore, AXL, AKT and ERK signaling were all decreased in response to R428 treatment, alongside the expression levels of MMP2 and MMP9. In conclusion, the results of the present study suggested that R428 treatment may suppress ESCC tumor cell proliferation and invasion, representing a potential therapeutic target for ESCC.

LC-MS/MS assay for the quantification of foretinib in rat plasma and its application to preclinical pharmacokinetic study

A simple and sensitive ultra-high-performance liquid chromatography tandem mass spectrometric method was developed and validated for the determination of foretinib in rat plasma. The analyte and internal standard were extracted from the bio-samples with acetonitrile and then separated on an Acquity UPLC BEH C₁₈ column (50 × 2.1 mm, 1.7 μm) using 0.1% formic acid aqueous and acetonitrile as mobile phase, at a flow rate of 0.4 ml/min. The mass detection was performed in positive selected reaction monitoring mode with precursor-to-product transitions at m/z 317.1 > 128.1 for foretinib and m/z 502.2 > 323.1 for internal standard. The assay was demonstrated to be linear in the concentration range of 0.5-1000 ng/ml, with correlation coefficient >0.999. The mean extraction recovery of foretinib from rat plasma was within the range of 84.55-88.09%, while the matrix effect was in the range of 88.56-99.21%. The intra- and inter-day precisions were <12.95% and the accuracy ranged from -7.55 to 8.57%. Foretinib was stable in rat plasma under the tested storage conditions. The validated assay was successfully applied to the pharmacokinetic study of foretinib in the rats. The results revealed that foretinib showed moderate elimination half-life, low clearance and dose-independent pharmacokinetic profiles inrats.

Rational Drug Design of Axl Tyrosine Kinase Type I Inhibitors as Promising Candidates Against Cancer

The high level of Axl tyrosine kinase expression in various cancer cell lines makes it an attractive target for the development of anti-cancer drugs. In this study, we carried out several sets of in silico screening for the ATP-competitive Axl kinase inhibitors based on different molecular docking protocols. The best drug-like candidates were identified, after parental structure modifications, by their highest affinity to the target protein. We found that our newly designed compound R5, a derivative of the R428 patented analog, is the most promising inhibitor of the Axl kinase according to the three molecular docking algorithms applied in the study. The molecular docking results are in agreement with the molecular dynamics simulations using the MM-PBSA/GBSA implicit solvation models, which confirm the high affinity of R5 toward the protein receptor. Additionally, the selectivity test against other kinases also reveals a high affinity of R5 toward ABL1 and Tyro3 kinases, emphasizing its promising potential for the treatment of malignant tumors.

Molecular mechanisms of tobacco induced oral and oropharyngeal cancer: Results of a tissue microarray and immunohistochemistry-based study from a tertiary cancer center in India

BACKGROUND

It is well established that chronic exposure to tobacco induces head and neck cancers but the exact etiopathogenesis is not known. Though studies have shown expression of TIMP1, EPS8 and AXL in cancers, their role in tobacco-induced cancers is not known. We aimed this study to evaluate the role of these molecules in oral and oropharyngeal squamous cell cancers (SCC).

MATERIALS AND METHODS

In this single institutional study, 31 patients of oral and oropharyngeal SCC with history of chewing tobacco were included. Smokers were excluded from the study. After informed consent biopsies were taken from affected and contralateral normal mucosa. Paraffin blocks were made and tissue microarray (TMA) were constructed using these blocks. Immunohistochemistry (IHC) for TIMP1, EPS8, AXL kinase was carried out on these tissue microarrays. The intensity of staining was scored from 0 to 3+, related to expression of each of the three molecules.

RESULTS

The expression of TIMP1, EPS8 and AXL kinase was significantly more in the cancerous mucosa versus non-cancerous mucosa (P = 0.000 in all three) in oral and oropharyngeal SCC exposed to chewing tobacco.

CONCLUSION

Immunohistochemical expression of these molecular markers in oral and oropharyngeal SCC correlated with their molecular based studies. Significant IHC expression of TIMP1, EPS8 and AXL establishes their role in the pathogenesis of oral and oropharyngeal squamous cell carcinomas. Novel targeted therapies may be researched that can detect and target these molecules at an earlier stage of pathogenesis of these tumors.

The Esophageal Cancer and the PI3K/AKT/mTOR Signaling Regulatory microRNAs: a Novel Marker for Prognosis, and a Possible Target for Immunotherapy

The Phosphatidylinositol 3-kinase/AKT/Mammalian Target of Rapamycin (PI3K/AKT/mTOR) pathway has a critical regulatory role in cell biology including translation, transcription, and autophagy. Dysregulation of this pathway is involved in the pathogenesis, development, and prognosis of esophageal cancer that has been assessed in the recent years and its potential as a target in therapy. This report summarizes the current knowledge about PI3K/AKT/mTOR pathway and its cross-talk with a focus on the value of targeting this pathway as a potential therapeutic target in the treatment of esophageal cancer.

Cabozantinib (XL184) and R428 (BGB324) Inhibit the Growth of Esophageal Squamous Cell Carcinoma (ESCC)

Esophageal squamous cell carcinoma (ESCC) is a deadly disease for which no effective targeted therapeutic agent has been approved. Both AXL and c-MET have been reported to be independent prognostic factors for ESCC. Thus, inhibitors of AXL/c-MET might have great potential as targeted therapy for ESCC. In the current study, we evaluated the therapeutic potential of the AXL/c-MET selective inhibitors, R428 and cabozantinib, in cell and mouse xenograft models. We demonstrated that both R428 and cabozantinib significantly inhibited the growth of CE81T and KYSE-70 ESCC cells and showed by wound-healing assay that they both inhibited ESCC cell migration. In the animal model, ESCC xenograft models were established by injecting KYSE-70 cells with Matrigel into the upper back region of NOD-SCID male mice followed by treatment with vehicle control, R428 (50 mg/kg/day), cisplatin (1.0 mg/kg), or cabozantinib (30 mg/kg/day) for the indicated number of days. R428 alone significantly inhibited ESCC tumor growth compared to the vehicle; however, no synergistic effect with cisplatin was observed. Notably, the dramatic efficacy of cabozantinib alone was observed in the mouse xenograft model. Collectively, our study demonstrated that both cabozantinib and R428 inhibit ESCC growth in cell and xenograft models. The results reveal the great potential of using cabozantinib for targeted therapy of ESCC.

AXL receptor tyrosine kinase as a promising anti-cancer approach: functions, molecular mechanisms and clinical applications

Molecular targeted therapy for cancer has been a research hotspot for decades. AXL is a member of the TAM family with the high-affinity ligand growth arrest-specific protein 6 (GAS6). The Gas6/AXL signalling pathway is associated with tumour cell growth, metastasis, invasion, epithelial-mesenchymal transition (EMT), angiogenesis, drug resistance, immune regulation and stem cell maintenance. Different therapeutic agents targeting AXL have been developed, typically including small molecule inhibitors, monoclonal antibodies (mAbs), nucleotide aptamers, soluble receptors, and several natural compounds. In this review, we first provide a comprehensive discussion of the structure, function, regulation, and signalling pathways of AXL. Then, we highlight recent strategies for targeting AXL in the treatment of cancer.AXL-targeted drugs, either as single agents or in combination with conventional chemotherapy or other small molecule inhibitors, are likely to improve the survival of many patients. However, future investigations into AXL molecular signalling networks and robust predictive biomarkers are warranted to select patients who could receive clinical benefit and to avoid potential toxicities.

DS-1205b, a novel selective inhibitor of AXL kinase, blocks resistance to EGFR-tyrosine kinase inhibitors in a non-small cell lung cancer xenograft model

The AXL receptor tyrosine kinase is involved in signal transduction in malignant cells. Recent studies have shown that the AXL upregulation underlies epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI) resistance in EGFR-mutant non-small cell lung cancer (NSCLC). In this study, we investigated the effect of DS-1205b, a novel and selective inhibitor of AXL, on tumor growth and resistance to EGFR TKIs. In AXL-overexpressing NIH3T3 cells, DS-1205b potently inhibited hGAS6 ligand-induced migration in vitro and exerted significant antitumor activity in vivo. AXL was upregulated by long-term erlotinib or osimertinib treatment in HCC827 EGFR-mutant NSCLC cells, and DS-1205b treatment in combination with osimertinib or erlotinib effectively inhibited signaling downstream of EGFR in a cell-based assay. In an HCC827 EGFR-mutant NSCLC xenograft mouse model, combination treatment with DS-1205b and erlotinib significantly delayed the onset of tumor resistance compared to erlotinib monotherapy, and DS-1205b restored the antitumor activity of erlotinib in erlotinib-resistant tumors. DS-1205b also delayed the onset of resistance when used in combination with osimertinib in the model. These findings strongly suggest that DS-1205b can prolong the therapeutic benefit of EGFR TKIs in nonclinical as well as clinical settings.

Axl Inhibitor R428 Enhances TRAIL-Mediated Apoptosis Through Downregulation of c-FLIP and Survivin Expression in Renal Carcinoma

R428, a selective small molecule Axl inhibitor, is known to have anti-cancer effects, such as inhibition of invasion and proliferation and induction of cell death in cancer cells. The Axl receptor tyrosine kinase is highly expressed in cancer cells and the level of Axl expression is associated with survival, metastasis, and drug resistance of many cancer cells. However, the effect of Axl inhibition on overcoming anti-cancer drugs resistance is unclear. Therefore, we investigated the capability of Axl inhibition as a therapeutic agent for the induction of TRAIL (tumor necrosis factor-related apoptosis-inducing ligand) sensitivity. In this study, R428 markedly sensitized cancer cells to TRAIL-induced apoptotic cell death, but not in normal human skin fibroblast (HSF) and human umbilical vein cells (EA.hy926). Moreover, knockdown of Axl by siRNA also increased TRAIL-induced apoptosis. R428 decreased c-FLIP proteins levels via induction of miR-708 expression and survivin protein levels at the post-translational level, and we found that knockdown of Axl also decreased both c-FLIP and survivin protein expression. Overexpression of c-FLIP and survivin markedly inhibited R428 plus TRAIL-induced apoptosis. Furthermore, R428 sensitized cancer cells to multiple anti-cancer drugs-mediated cell death. Our results provide that inhibition of Axl could improve sensitivity to TRAIL through downregulation of c-FLIP and survivin expression in renal carcinoma cells. Taken together, Axl may be a tempting target to overcome TRAIL resistance.

Long non-coding antisense RNA GAS6-AS1 supports gastric cancer progression via increasing GAS6 expression

OBJECTIVE

As one broader class of non-coding RNAs (lncRNAs), non-coding antisense (AS) transcripts are functionally characterized to play pivotal roles in various pathophysiological processes, including tumor biology.

METHODS

In this study, the exact biological functions and regulation mechanisms of GAS6-AS1 in gastric cancer (GC) was examined.

RESULTS

The expression of GAS6-AS1 was markedly upregulated in GC tissues and is associated with advanced stage (III + IV) of GC patients. Gain-of-function and loss-of-function experiments showed that GAS6-AS1 promoted cell proliferation, migration, invasion ability in vitro and xenograft tumor growth in vivo by promoting entry into S-phase. The mechanistic investigations showed that GAS6-AS1 can control the expression of its cognate sense gene GAS6 at the transcriptional or translational levels by forming a RNA-RNA duplex, consequently inducing an increase of AXL level and driveling AXL signaling pathway activation.

CONCLUSIONS

Taken together, our studies indicate that GAS6-AS1 significantly driving the aggressive phenotype in GC through activating its cognate sense gene GAS6, and provides a more complete understanding of GAS6-AS1 as a potential therapeutic target for GC.

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

The receptor tyrosine kinase Axl and its ligand Gas6 regulate fundamental biological processes, including cell proliferation, survival and motility, through multiple downstream signaling pathways. Evidence to date suggests that aberrant Axl expression frequently occurs in many malignancies, including hepatocellular carcinoma, and that this is critical for promoting cell proliferation, migration, angiogenesis and metastasis. Moreover, deregulated Axl expression or activation is reportedly associated with resistance to cancer drugs and targeted cancer therapies. Thus, Axl inhibitors may represent a novel therapeutic approach for cancer treatment. This Review summarizes the latest advances concerning the biological role of Axl in hepatocellular carcinoma and its potential clinical relevance.

Acyl-CoA dehydrogenase long chain expression is associated with esophageal squamous cell carcinoma progression and poor prognosis

Background

Acyl-CoA dehydrogenase long chain (ACADL) was revealed to have a correlation with malignant progression of cancer. However, whether ACADL plays a role in clinical therapy remains unclear. The clinicopathological role of ACADL in esophageal squamous cell carcinoma (ESCC) will be discussed in this study.

Materials and methods

The expression of ACADL was analyzed via real-time PCR and Western blotting to assess mRNA and protein levels in ESCC cell lines and normal esophageal epithelial cells (NEECs), in six paired ESCC tumors and relative normal tissues. Furthermore, immunohistochemical staining was performed on 135 paraffin-embedded ESCC specimens to assess ACADL expression. The clinicopathological significance of ACADL expression was further investigated via survival analysis and Cox regression analysis.

Results

ACADL was found to be markedly upregulated in ESCC cell lines when compared with NEECs. Moreover, various experiments such as quantitative real-time PCR, Western blot, and immunohistochemical analyses all revealed that ACADL expression was increased in all six paired ESCC tumors and matched normal tissues. Furthermore, immunohistochemical analysis revealed an increased level of ACADL protein expression in all 135 paraffin-embedded samples from ESCC patients, which increased with disease progression.

Conclusion

We demonstrated that ACADL is overexpressed in ESCC, both in cell lines and clinical specimens. ACADL is found to be a vital regulator in ESCC progression and can predict a worse outcome for ESCC patients, suggesting that ACADL might be a valuable molecule to be targeted for clinical therapy of ESCC treatment.

The Dual Role of TAM Receptors in Autoimmune Diseases and Cancer: An Overview

Receptor tyrosine kinases (RTKs) regulate cellular processes by converting signals from the extracellular environment to the cytoplasm and nucleus. Tyro3, Axl, and Mer (TAM) receptors form an RTK family that plays an intricate role in tissue maintenance, phagocytosis, and inflammation as well as cell proliferation, survival, migration, and development. Defects in TAM signaling are associated with numerous autoimmune diseases and different types of cancers. Here, we review the structure of TAM receptors, their ligands, and their biological functions. We discuss the role of TAM receptors and soluble circulating TAM receptors in the autoimmune diseases systemic lupus erythematosus (SLE) and multiple sclerosis (MS). Lastly, we discuss the effect of TAM receptor deregulation in cancer and explore the therapeutic potential of TAM receptors in the treatment of diseases.

Combined detection of IL-6 and IL-8 is beneficial to the diagnosis of early stage esophageal squamous cell cancer: a preliminary study based on the screening of serum markers using protein chips

Background

The diagnosis rate of early stage esophageal squamous cell carcinoma (ESCC) is low due to the lack of specific tumor markers. Seeking for these markers is beneficial to improve the early diagnosis rate and the prognosis of patients. This study profiles the differentially expressed proteins of early stage ESCC patients via the AAH-BLG-507 protein chip, which further consolidates the clinical evidence of ESCC diagnosis.

Materials and methods

In this study, 20 serum samples were collected from Taihe Hospital between August 2016 and June 2017. Ten of them carried ESCC, while the rest were healthy controls. To profile the proteins’ expression level, the AAH-BLG-507 protein chip was used, and both highly expressed and lowly expressed proteins were fished out. Meanwhile, their biological roles were examined by using Gene Ontology (GO) database and String database, and they were further verified by ELISA.

Results

Results showed that the expression levels of AXL, ARTN, Ang2, BDNF, BMP7, cripto-1, CCL28, E-selectin, IL-6, IL-8 and SHH in the serum of early ESCC were significantly upregulated (P<0.05), particularly IL-6 and IL-8. The expression levels of TSP1 and MMP-8 were markedly downregulated (P<0.05). Analysis showed that these proteins were mainly involved in angiogenesis, signal transduction, cell proliferation and migration, indicating the close relationship with the development of ESCC.

Conclusion

It suggested that IL-6 and IL-8 proteins could be considered as the markers for ESCC diagnosis.

A reliable and stable method for the determination of foretinib in human plasma by LC-MS/MS: Application to metabolic stability investigation and excretion rate

Foretinib (GSK1363089) is a multiple receptor tyrosine kinases inhibitor. In this study, a reliable, fast liquid chromatography-tandem mass spectrometric method was described for assaying foretinib in plasma, urine, and rat liver microsome samples. Simple extraction procedure by protein preciptation with acetonitrile was implemented for foretinib and brigatinib (internal standard) analysis. Chromatographic resolution of analytes was achieved on C₁₈ column with the help of isocratic mobile phase. The binary mobile phase consisted of 60% ammonium formate (10 mM, pH 4.2) and 40% acetonitrile at a flow rate of 0.25 mL/min. Run time was 3 min, and both foretinib and brigatinib were eluted within 0.74 and 1.95 min; they were detected in positive ion mode utilizing multiple reactions monitoring mode. Linearity of the proposed method ranged from 5 to 500 ng/mL (r²≥ 0.9993) in the human plasma. Lower limit of quantification and detection were 6.0 and 1.8 ng/mL, respectively. Intraday and interday precision and accuracy were 0.16 to 1.67 % and -2.39 to -0.52 %. In vitro half-life and intrinsic clearance were 24.93 min and 6.56 mL/min/kg, respectively. Literature review showed that no previous studies have been proposed for the analytical quantification of foretinib in human plasma or its metabolic stability. The established method was also applied to estimate the rate of foretinib excretion in rat urine. The developed method can be used for foretinib pharmacokinetic applications.

Targeting AXL overcomes resistance to docetaxel therapy in advanced prostate cancer

Resistance to docetaxel is a major clinical problem in advanced prostate cancer. The overexpression of AXL receptor tyrosine kinase (AXL) has been correlated with chemotherapeutic drug resistance. However, the role of AXL expression in docetaxel resistance in prostate cancer is yet unclear. In this study, we demonstrate that AXL is overexpressed and activated independent of Gas6 in docetaxel-resistant prostate cancer cells (PC3-DR and DU145-DR). Moreover, we show that forced overexpression of AXL in PC3 and DU145 cells is sufficient to induce resistance to docetaxel in these cell lines. Notably, genetic or pharmacologic inhibition of AXL in the resistant models suppressed cell proliferation, migration, invasion, and tumor growth, and these effects were significantly augmented when AXL inhibition was combined with docetaxel treatment. Mechanistically, we found that AXL inhibition led to reversion of the epithelial-mesenchymal transition (EMT) phenotype and decreased the expression of ATP-binding cassette B1 (ABCB1). Overall, our results identify AXL as an important mediator of docetaxel resistance in prostate cancer. We propose that AXL-targeted therapy, in combination with docetaxel, has the potential to improve the response to docetaxel therapy and reduce resistance induced by prolonged docetaxel therapy in prostate cancer.

Expression, regulation and targeting of receptor tyrosine kinases in esophageal squamous cell carcinoma

Esophageal cancer is one of the most common types of cancer, which is a leading cause of cancer-related death worldwide. Based on histological behavior, it is mainly of two types (i) Esophageal squamous cell carcinoma (ESCC), and (ii) esophageal adenocarcinoma (EAD or EAC). In astronomically immense majority of malignancies, receptor tyrosine kinases (RTKs) have been kenned to play a consequential role in cellular proliferation, migration, and metastasis of the cells. The post-translational modifications (PTMs) including phosphorylation of tyrosine (pY) residue of the tyrosine kinase (TK) domain have been exploited for treatment in different malignancies. Lung cancer where pY residues of EGFR have been exploited for treatment purpose in lung adenocarcinoma patients, but we do not have such kind of felicitously studied and catalogued data in ESCC patients. Thus, the goal of this review is to summarize the studies carried out on ESCC to explore the role of RTKs, tyrosine kinase inhibitors, and their pertinence and consequentiality for the treatment of ESCC patients.

Expression, regulation and targeting of receptor tyrosine kinases in esophageal squamous cell carcinoma

Esophageal cancer is one of the most common types of cancer, which is a leading cause of cancer-related death worldwide. Based on histological behavior, it is mainly of two types (i) Esophageal squamous cell carcinoma (ESCC), and (ii) esophageal adenocarcinoma (EAD or EAC). In astronomically immense majority of malignancies, receptor tyrosine kinases (RTKs) have been kenned to play a consequential role in cellular proliferation, migration, and metastasis of the cells. The post-translational modifications (PTMs) including phosphorylation of tyrosine (pY) residue of the tyrosine kinase (TK) domain have been exploited for treatment in different malignancies. Lung cancer where pY residues of EGFR have been exploited for treatment purpose in lung adenocarcinoma patients, but we do not have such kind of felicitously studied and catalogued data in ESCC patients. Thus, the goal of this review is to summarize the studies carried out on ESCC to explore the role of RTKs, tyrosine kinase inhibitors, and their pertinence and consequentiality for the treatment of ESCC patients.

The prognostic role of Gas6/Axl axis in solid malignancies: a meta-analysis and literature review

Background

Axl is a receptor tyrosine kinase that is involved in many pathological conditions and carcinogenesis. Gas6 is the major ligand of Axl. Activation of Gas6/Axl pathway is essential for cancer development. However, its prognostic significance in solid tumors remains unclear. Therefore, we performed this meta-analysis to elucidate the prognostic impact of Axl.

Methods

Published studies on Axl or Gas6 expression and overall survival (OS) and/or disease-free survival (DFS) were searched from databases. The outcome measurement is hazard ratio (HR) for OS or DFS related to Axl/Gas6 expression. Meta-analysis was performed using RevMan. The pooled HR was calculated by fixed-/random-effect models.

Results

A total of 3,344 patients from 25 studies were included. The results of meta-analysis showed that Axl overexpression was correlated with shorter OS (HR: 2.03, p<0.0001) and DFS (HR: 1.85, p<0.0001). In subgroup analysis, Axl expression was significantly correlated with poor prognosis in hepatocellular, esophageal and lung cancer. Axl expression was associated with differentiation grade, TNM stage, lymph node and distant metastasis.

Conclusion

These results suggest that Axl overexpression is correlated with poor prognosis in solid tumors. This correlation varies among different types of cancers. More studies are needed to further investigate the prognostic value of Axl.

AXL is a marker for epithelial-mesenchymal transition in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a common cancer in China and certain other parts of the world with a dismal prognosis for affected patients. AXL is a member of the TYRO3-AXL-MER family of receptor tyrosine kinases, and has been revealed to be an important mediator of epithelial-mesenchymal transition (EMT) in several types of cancer. However, to the best of our knowledge, its function in EMT in ESCC cells has not yet been examined. The present study employed two independent ESCC mRNA profile datasets and revealed that AXL is associated with several EMT markers. Gene Set Enrichment Analysis indicated that EMT occurs more in ESCC with high AXL expression. Analysis on another dataset demonstrated further that increased expression of AXL in ESCC is associated with increased migratory ability. Collectively, the results of the present study provide evidence that AXL is a marker for EMT in ESCC.

Genetic polymorphisms of ATG5 predict survival and recurrence in patients with early-stage esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a deadly disease with high risk of tumor recurrence even among patients with an early pathologic stage of tumor. In the current study, we investigate the association between 20 SNPs of the ATG5 gene and prognosis of patients with early-stage ESCC. A total of 305 patients diagnosed with early-stage ESCC were enrolled in the study and randomly assigned to a training set (n=93) or replication set (n=212). The genotypes of candidate SNPs (single nucleotide polymorphisms) within ATG5 were analyzed and correlated with the prognosis of ESCC patients. We repeatedly demonstrated that 3 SNPs in ATG5, rs1322178, rs3804329, and rs671116, were significantly correlated with the prognosis of patients with early-stage ESCC (HR[95 % CI]=2.01[1.19-3.40], p=0.009 for ATG5: rs1322178; HR[95 % CI]=1.88 [1.08-3.26], p=0.025 for ATG5:rs3804329; HR[95 % CI]=1.73[1.24-2.42], p=0.001 for ATG5:rs671116, in combined group). Both rs1322178 and rs3804329 can predict early distant metastasis of patients. Furthermore, increased expression of ATG5 was observed in ESCC tumor tissue as compared to adjacent normal tissue. Moreover, higher levels of ATG5 expression in both normal and tumor tissues exhibited a trend to correlate with poor prognosis of patients. However, the expression of ATG5 did not correlate with these 3 relevant prognostic SNPs. We concluded that hereditary genetic polymorphisms and gene expression of ATG5 can serve as prognostic predictors of patients with early-stage ESCC.

AXL-Driven EMT State as a Targetable Conduit in Cancer

The receptor tyrosine kinase (RTK) AXL has been intrinsically linked to epithelial-mesenchymal transition (EMT) and promoting cell survival, anoikis resistance, invasion, and metastasis in several cancers. AXL signaling has been shown to directly affect the mesenchymal state and confer it with aggressive phenotype and drug resistance. Recently, the EMT gradient has also been shown to rewire the kinase signaling nodes that facilitate AXL-RTK cross-talk, protracted signaling, converging on ERK, and PI3K axes. The molecular mechanisms underplaying the regulation between the kinome and EMT require further elucidation to define targetable conduits. Therapeutically, as AXL inhibition has shown EMT reversal and resensitization to other tyrosine kinase inhibitors, mitotic inhibitors, and platinum-based therapy, there is a need to stratify patients based on AXL dependence. This review elucidates the role of AXL in EMT-mediated oncogenesis and highlights the reciprocal control between AXL signaling and the EMT state. In addition, we review the potential in inhibiting AXL for the development of different therapeutic strategies and inhibitors. Cancer Res; 77(14); 3725-32. ©2017 AACR.

2-Acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylcarbonylamino) phenyl carbamoylsulfanyl] propionic acid, a glutathione reductase inhibitor, induces G2/M cell cycle arrest through generation of thiol oxidative stress in human esophageal cancer cells

Esophageal squamous cell carcinoma (ESCC) is a highly malignant cancer with poor response to both of chemotherapy and radiotherapy. 2-Acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanylcarbonylamino) phenyl carbamoylsulfanyl] propionic acid (2-AAPA), an irreversible inhibitor of glutathione reductase (GR), is able to induce intracellular oxidative stress, and has shown anticancer activity in many cancer cell lines. In this study, we investigated the effects of 2-AAPA on the cell proliferation, cell cycle and apoptosis and aimed to explore its mechanism of action in human esophageal cancer TE-13 cells. It was found that 2-AAPA inhibited growth of ESCC cells in a dose-dependent manner and it did not deplete reduced glutathione (GSH), but significantly increased the oxidized form glutathione (GSSG), resulting in decreased GSH/GSSG ratio. In consequence, significant reactive oxygen species (ROS) production was observed. The flow cytometric analysis revealed that 2-AAPA inhibited growth of esophageal cancer cells through arresting cell cycle in G₂/M phase, but apoptosis-independent mechanism. The G₂/M arrest was partially contributed by down-regulation of protein expression of Cdc-25c and up-regulation of phosphorylated Cdc-2 (Tyr15), Cyclin B1 (Ser147) and p53. Meanwhile, 2-AAPA-induced thiol oxidative stress led to increased protein S-glutathionylation, which resulted in α-tubulin S-glutathionylation-dependent depolymerization of microtubule in the TE-13 cells. In conclusion, we identified that 2-AAPA as an effective thiol oxidative stress inducer and proliferation of TE-13 cells were suppressed by G₂/M phase cell cycle arrest, mainly, through α-tubulin S-glutathionylation-mediated microtubule depolymerization. Our results may introduce new target and approach for esophageal cancer therapy through generation of GR-mediated thiol oxidative stress.

Giving AXL the axe: targeting AXL in human malignancy

The receptor tyrosine kinase AXL, activated by a complex interaction between its ligand growth arrest-specific protein 6 and phosphatidylserine, regulates various vital cellular processes, including proliferation, survival, motility, and immunologic response. Although not implicated as an oncogenic driver itself, AXL, a member of the TYRO3, AXL, and MERTK family of receptor tyrosine kinases, is overexpressed in several haematologic and solid malignancies, including acute myeloid leukaemia, non-small cell lung cancer, gastric and colorectal adenocarcinomas, and breast and prostate cancers. In the context of malignancy, evidence suggests that AXL overexpression drives wide-ranging processes, including epithelial to mesenchymal transition, tumour angiogenesis, resistance to chemotherapeutic and targeted agents, and decreased antitumor immune response. As a result, AXL is an attractive candidate not only as a prognostic biomarker in malignancy but also as a target for anticancer therapies. Several AXL inhibitors are currently in preclinical and clinical development. This article reviews the structure, regulation, and function of AXL; the role of AXL in the tumour microenvironment; the development of AXL as a therapeutic target; and areas of ongoing and future investigation.

LC-MS/MS reveals the formation of aldehydes and iminium reactive intermediates in foretinib metabolism: phase I metabolic profiling

Using LC-MS/MS, six phase I foretinib metabolites in addition to four potential reactive metabolites, two aldehydes and two iminium ions, were detected and the bioactivation pathways were proposed.

The Receptor Tyrosine Kinase AXL in Cancer Progression

The AXL receptor tyrosine kinase (AXL) has emerged as a promising therapeutic target for cancer therapy. Recent studies have revealed a central role of AXL signaling in tumor proliferation, survival, stem cell phenotype, metastasis, and resistance to cancer therapy. Moreover, AXL is expressed within cellular components of the tumor microenvironment where AXL signaling contributes to the immunosuppressive and protumorigenic phenotypes. A variety of AXL inhibitors have been developed and are efficacious in preclinical studies. These agents offer new opportunities for therapeutic intervention in the prevention and treatment of advanced disease. Here we review the literature that has illuminated the cellular and molecular mechanisms by which AXL signaling promotes tumor progression and we will discuss the therapeutic potential of AXL inhibition for cancer therapy.

The Role of TAM Family Receptors in Immune Cell Function: Implications for Cancer Therapy

The TAM receptor protein tyrosine kinases-Tyro3, Axl, and Mer-are essential regulators of immune homeostasis. Guided by their cognate ligands Growth arrest-specific gene 6 (Gas6) and Protein S (Pros1), these receptors ensure the resolution of inflammation by dampening the activation of innate cells as well as by restoring tissue function through promotion of tissue repair and clearance of apoptotic cells. Their central role as negative immune regulators is highlighted by the fact that deregulation of TAM signaling has been linked to the pathogenesis of autoimmune, inflammatory, and infectious diseases. Importantly, TAM receptors have also been associated with cancer development and progression. In a cancer setting, TAM receptors have a dual regulatory role, controlling the initiation and progression of tumor development and, at the same time, the associated anti-tumor responses of diverse immune cells. Thus, modulation of TAM receptors has emerged as a potential novel strategy for cancer treatment. In this review, we discuss our current understanding of how TAM receptors control immunity, with a particular focus on the regulation of anti-tumor responses and its implications for cancer immunotherapy.

Translational research in thoracic surgery-the National Taiwan University Hospital experience

Thoracic surgeons should be more aware of the latest information about histopathological, genetic and epigenetic alterations that may influence treatment policy and patient outcome in the biomolecular era. Translational research studies often produce a promising diagnostic tool or new treatment that can be used clinically. The results of these translational studies may even change the practical guidelines and current staging system in thoracic malignancies. The following article summarizes the experiences of translational research in esophageal cancer and non-small cell lung cancer (NSCLC) at National Taiwan University Hospital in Taiwan.