ERK Signal Suppression and Sensitivity to CH5183284/Debio 1347, a Selective FGFR Inhibitor

Pyrrole-containing hybrids as potential anticancer agents: An insight into current developments and structure-activity relationships

Cancer poses a significant threat to human health. Therefore, it is urgent to develop potent anti-cancer drugs with excellent inhibitory activity and no toxic side effects. Pyrrole and its derivatives are privileged heterocyclic compounds with significant diverse pharmacological effects. These compounds can target various aspects of cancer cells and have been applied in clinical settings or are undergoing clinical trials. As a result, pyrrole has emerged as a promising drug scaffold and has been further probed to get novel entities for the treatment of cancer. This article reviews recent research progress on anti-cancer drugs containing pyrrole. It focuses on the mechanism of action, biological activity, and structure-activity relationships of pyrrole derivatives, aiming to assist in designing and synthesizing innovative pyrrole-based anti-cancer compounds.

A Phase I Study of KIN-3248, an Irreversible Small-molecule Pan-FGFR Inhibitor, in Patients with Advanced FGFR2/3-driven Solid Tumors

PURPOSE

Despite efficacy of approved FGFR inhibitors, emergence of polyclonal secondary mutations in the FGFR kinase domain leads to acquired resistance. KIN-3248 is a selective, irreversible, orally bioavailable, small-molecule inhibitor of FGFR1-4 that blocks both primary oncogenic and secondary kinase domain resistance FGFR alterations.

EXPERIMENTAL DESIGN

A first-in-human, phase I study of KIN-3248 was conducted in patients with advanced solid tumors harboring FGFR2 and/or FGFR3 gene alterations (NCT05242822). The primary objective was determination of MTD/recommended phase II dose (RP2D). Secondary and exploratory objectives included antitumor activity, pharmacokinetics, pharmacodynamics, and molecular response by circulating tumor DNA (ctDNA) clearance.

RESULTS

Fifty-four patients received doses ranging from 5 to 50 mg orally daily across six cohorts. Intrahepatic cholangiocarcinoma (48.1%), gastric (9.3%), and urothelial (7.4%) were the most common tumors. Tumors harbored FGFR2 (68.5%) or FGFR3 (31.5%) alterations-23 (42.6%) received prior FGFR inhibitors. One dose-limiting toxicity (hypersensitivity) occurred in cohort 1 (5 mg). Treatment-related, adverse events included hyperphosphatemia, diarrhea, and stomatitis. The MTD/RP2D was not established. Exposure was dose proportional and concordant with hyperphosphatemia. Five partial responses were observed; 4 in FGFR inhibitor naïve and 1 in FGFR pretreated patients. Pretreatment ctDNA profiling confirmed FGFR2/3 alterations in 63.3% of cases and clearance at cycle 2 associated with radiographic response.

CONCLUSION

The trial was terminated early for commercial considerations; therefore, RP2D was not established. Preliminary clinical data suggest that KIN-3248 is a safe, oral FGFR1-4 inhibitor with favorable pharmacokinetic parameters, though further dose escalation was required to nominate the MTD/RP2D.

SIGNIFICANCE

KIN-3248 was a rationally designed, next generation selective FGFR inhibitor, that was effective in interfering with both FGFR wild-type and mutant signaling. Clinical data indicate that KIN-3248 is safe with a signal of antitumor activity. Translational science support the mechanism of action in that serum phosphate was proportional with exposure, paired biopsies suggested phospho-ERK inhibition (a downstream target of FGFR2/3), and ctDNA clearance may act as a RECIST response surrogate.

Dual-specificity phosphatases: therapeutic targets in cancer therapy resistance

PURPOSE

Therapy resistance is the principal obstacle to achieving cures in cancer patients and its successful tackling requires a deep understanding of the resistance mediators. Increasing evidence indicates that tumor phosphatases are novel and druggable targets in translational oncology and their modulation may hinder tumor growth and motility and potentiate therapeutic sensitivity in various neoplasms via regulation of various signal transduction pathways. Dual-specificity phosphatases (DUSPs) are key players of cell growth, survival and death and have essential roles in tumor initiation, malignant progression and therapy resistance through regulation of the MAPK signaling pathway. In this review, different aspects of DUSPs are discussed.

METHODS

A comprehensive literature review was performed using various websites including PubMed.

RESULTS

We provide mechanistic insights into the roles of well-known DUSPs in resistance to a wide range of cancer therapeutic approaches including chemotherapy, radiation and molecular targeted therapy in human malignancies. Moreover, we discuss the development of DUSP modulators, with a focus on DUSP1 and 6 inhibitors. Ultimately, the preclinical investigations of small molecule inhibitors of DUSP1 and 6 are outlined.

CONCLUSION

Emerging evidence indicates that the DUSP family is aberrantly expressed in human malignancies and plays critical roles in determining sensitivity to a wide range of cancer therapeutic strategies through regulation of the MAPK signaling pathways. Consequently, targeting DUSPs and their downstream molecules can pave the way for more effective cancer therapies.

Current Development and Application of Anaerobic Glycolytic Enzymes in Urothelial Cancer

Urothelial cancer is a malignant tumor with metastatic ability and high mortality. Malignant tumors of the urinary system include upper tract urothelial cancer and bladder cancer. In addition to typical genetic alterations and epigenetic modifications, metabolism-related events also occur in urothelial cancer. This metabolic reprogramming includes aberrant expression levels of genes, metabolites, and associated networks and pathways. In this review, we summarize the dysfunctions of glycolytic enzymes in urothelial cancer and discuss the relevant phenotype and signal transduction. Moreover, we describe potential prognostic factors and risks to the survival of clinical cancer patients. More importantly, based on several available databases, we explore relationships between glycolytic enzymes and genetic changes or drug responses in urothelial cancer cells. Current advances in glycolysis-based inhibitors and their combinations are also discussed. Combining all of the evidence, we indicate their potential value for further research in basic science and clinical applications.

Synergistic effects of FGFR1 and PLK1 inhibitors target a metabolic liability in KRAS-mutant cancer

KRAS oncoprotein is commonly mutated in human cancer, but effective therapies specifically targeting KRAS-driven tumors remain elusive. Here, we show that combined treatment with fibroblast growth factor receptor 1 (FGFR1) and polo-like kinase 1 (PLK1) inhibitors evoke synergistic cytotoxicity in KRAS-mutant tumor models in vitro and in vivo. Pharmacological and genetic suppression of FGFR1 and PLK1 synergizes to enhance anti-proliferative effects and cell death in KRAS-mutant lung and pancreatic but not colon nor KRAS wild-type cancer cells. Mechanistically, co-targeting FGFR1 and PLK1 upregulates reactive oxygen species (ROS), leading to oxidative stress-activated c-Jun N-terminal kinase (JNK)/p38 pathway and E2F1-induced apoptosis. We further delineate that autophagy protects from PLK1/FGFR1 inhibitor cytotoxicity and that antagonizing the compensation mechanism by clinically approved chloroquine fully realizes the therapeutic potential of PLK1 and FGFR1 targeting therapy, producing potent and durable responses in KRAS-mutant patient-derived xenografts and a genetically engineered mouse model of Kras-induced lung adenocarcinoma. These results suggest a previously unappreciated role for FGFR1 and PLK1 in the surveillance of metabolic stress and demonstrate a synergistic drug combination for treating KRAS-mutant cancer.

Insights of fibroblast growth factor receptor 3 aberrations in pan-cancer and their roles in potential clinical treatment

Fibroblast growth factor receptor 3 (FGFR3) alters frequently across various cancer types and is a common therapeutic target in bladder urothelial carcinoma (BLCA) with FGFR3 variants. Although emerging evidence supports the role of FGFR3 in individual cancer types, no pan-cancer analysis is available. In this work, we used the open comprehensive datasets, covering a total of 10,953 patients with 10,967 samples across 32 TCGA cancer types, to identify the full alteration spectrum of FGFR3. FGFR3 abnormal expression, methylation patterns, alteration frequency, mutation location distribution, functional impact, and prognostic implications differed greatly from cancer to cancer. The overall alteration frequency of FGFR3 was relatively low in all cancers. Targetable mutations were mainly detected in BLCA, and S249C, Y373C, G370C, and R248C were hotspot mutations that could be targeted by an FDA approved erdafitinib. Genetic fusions were mainly observed in glioma, followed by BLCA. FGFR3-TACC3 was the most common fusion type which was proposed as novel therapeutic targets in glioma and was targetable with erdafitinib in BLCA. Lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC) were two lung cancer subtypes, FGFR3 fusion and hotspot mutation like S249C were observed more commonly in LUSC but not in LUAD. DNA methylation was correlated with the expression of FGFR3 and its downstream genes in some tumors. FGFG3 abnormal expression and alterations exhibited clinical correlations with patient prognosis in several tumors. This work exhibited the full alteration spectrum of FGFR3 and indicated several new clues for their application as potential therapeutic targets and prognostic indicators.

CRISPR-Mediated Kinome Editing Prioritizes a Synergistic Combination Therapy for FGFR1-Amplified Lung Cancer

Oncogenic activation of the FGFR pathway is frequent in lung and other cancers. However, due to drug resistance, pharmacological blockage of aberrant FGFR signaling has provided little clinical benefit in patients with FGFR-amplified tumors. The determining factors for the limited efficacy of FGFR-targeted therapy remain incompletely understood. In this study, we performed kinome-wide CRISPR/Cas9 loss-of-function screens in FGFR1-amplified lung cancer cells treated with an FGFR inhibitor. These screens identified PLK1 as a potent synthetic lethal target that mediates a resistance mechanism by overriding DNA damage and cell-cycle arrest upon FGFR1 inhibition. Genetic and pharmacological antagonism of PLK1 in combination with FGFR inhibitor therapy synergized to enhance antiproliferative effects and drove cancer cell death in vitro and in vivo through activation of the γH2AX-CHK-E2F1 axis. These findings suggest a previously unappreciated role for PLK1 in modulating FGFR1 inhibitor sensitivity and demonstrate a synergistic drug combination for treating FGFR1-amplified lung cancer. SIGNIFICANCE: The identification of PLK1 as a potent synthetic lethal target for FGFR-targeted therapy provides an innovative rationale for the treatment of lung and other FGFR1-amplified cancers.

Fibroblast Growth Factor Receptors (FGFRs) and Noncanonical Partners in Cancer Signaling

Increasing evidence indicates that success of targeted therapies in the treatment of cancer is context-dependent and is influenced by a complex crosstalk between signaling pathways and between cell types in the tumor. The Fibroblast Growth Factor (FGF)/FGF receptor (FGFR) signaling axis highlights the importance of such context-dependent signaling in cancer. Aberrant FGFR signaling has been characterized in almost all cancer types, most commonly non-small cell lung cancer (NSCLC), breast cancer, glioblastoma, prostate cancer and gastrointestinal cancer. This occurs primarily through amplification and over-expression of FGFR1 and FGFR2 resulting in ligand-independent activation. Mutations and translocations of FGFR1-4 are also identified in cancer. Canonical FGF-FGFR signaling is tightly regulated by ligand-receptor combinations as well as direct interactions with the FGFR coreceptors heparan sulfate proteoglycans (HSPGs) and Klotho. Noncanonical FGFR signaling partners have been implicated in differential regulation of FGFR signaling. FGFR directly interacts with cell adhesion molecules (CAMs) and extracellular matrix (ECM) proteins, contributing to invasive and migratory properties of cancer cells, whereas interactions with other receptor tyrosine kinases (RTKs) regulate angiogenic, resistance to therapy, and metastatic potential of cancer cells. The diversity in FGFR signaling partners supports a role for FGFR signaling in cancer, independent of genetic aberration.

Resistance to FGFR1-targeted therapy leads to autophagy via TAK1/AMPK activation in gastric cancer

BACKGROUND

Fibroblast growth factor receptor 1 (FGFR1) is frequently dysregulated in various tumors. FGFR inhibitors have shown promising therapeutic value in several preclinical models. However, tumors resistant to FGFR inhibitors have emerged, compromising therapeutic outcomes by demonstrating markedly aggressive metastatic progression; however, the underlying signaling mechanism of resistance remains unknown.

METHODS

We established FGFR inhibitor-resistant cell models using two gastric cancer (GC) cell lines, MGC-803 and BGC-823. RNA-seq was performed to determine the continuous cellular transcriptome changes between parental and resistant cells. We explored the mechanism of resistance to FGFR inhibitor, using a subcutaneous tumor model and GC patient-derived tumor organotypic culture.

RESULTS

We observed that FGFR1 was highly expressed in GC and FGFR1 inhibitor-resistant cell lines, demonstrating elevated levels of autophagic activity. These resistant cells were characterized by epithelial-mesenchymal transition (EMT) required to facilitate metastatic outgrowth. In drug-resistant cells, the FGFR1 inhibitor regulated GC cell autophagy via AMPK/mTOR signal activation, which could be blocked using either pharmacological inhibitors or essential gene knockdown. Furthermore, TGF-β-activated kinase 1 (TAK1) amplification and metabolic restrictions led to AMPK pathway activation and autophagy. In vitro and in vivo results demonstrated that the FGFR inhibitor AZD4547 and TAK1 inhibitor NG25 synergistically inhibited proliferation and autophagy in AZD4547-resistant cell lines and patient-derived GC organotypic cultures.

CONCLUSIONS

We elucidated the molecular mechanisms underlying primary resistance to FGFR1 inhibitors in GC, and revealed that the inhibition of FGFR1 and TAK1 signaling could present a potential novel therapeutic strategy for FGFR1 inhibitor-resistant GC patients.

Clinical Characteristics and Mutation Analyses of Ovarian Sertoli-Leydig Cell Tumors

BACKGROUND

There are limited studies on Sertoli-Leydig cell tumors (SLCTs) and no data in the population of Chinese patients with SLCTs from the genetic level. In addition, previous studies on SLCTs have focused exclusively on mutations in the DICER1 gene and no data exists on the genetic landscape of SLCTs.

METHODS

Patients with moderately or poorly differentiated SLCTs who underwent surgical resection between January 2012 and October 2018 in our institution were recruited. Whole exome sequencing was performed on formalin-fixed, paraffin-embedded tumor tissue and peripheral blood or normal tissue samples.

RESULTS

Seventeen patients were recruited with 19 tumor samples. The rate of tumor-associated germline mutations was 6 of 17 (35.3%), and that of DICER1 germline mutations was 4 of 17 (23.5%). Regarding clinical relapse, patients with germline tumor-associated mutations had significantly poorer prognosis than those without (p = .007), and those with germline DICER1 mutations were relatively more likely to exhibit clinical relapse, although not to a significant degree (p = .069). Regarding somatic mutations, firstly, the subclone evolution analysis demonstrated that the two tumors on the contralateral ovary were primary tumors, respectively. Secondly, somatic mutations were most commonly found in CDC27 (10/19, 52.6%), DICER1 (4/19, 21.1%), and MUC22 (4/19, 21.1%). And the analysis of cancer cell fractions showed that DICER1 mutations were correlated with tumorigenesis of SLCTs. The rates of germline and somatic DICER1 mutations were higher in patients who were younger than 18 years than those in older patients (p = .022 and p = .001, respectively).

CONCLUSION

Our study indicates that genetic testing may have important clinical significance for patients with SLCTs, particularly for younger patients.

IMPLICATIONS FOR PRACTICE

Bilateral ovarian Sertoli-Leydig cell tumors were verified to be primary tumors from the genetic perspective. The rates of germline and somatic DICER1 mutations were 4 of 17 (23.5%) and 4 of 19 (21.1%), respectively. The rates of germline and somatic DICER1 mutations were higher in patients who were younger than 18 years than those in older patients (p = .022 and p = .001, respectively).

N-cadherin-regulated FGFR ubiquitination and degradation control mammalian neocortical projection neuron migration

The functions of FGF receptors (FGFRs) in early development of the cerebral cortex are well established. Their functions in the migration of neocortical projection neurons, however, are unclear. We have found that FGFRs regulate multipolar neuron orientation and the morphological change into bipolar cells necessary to enter the cortical plate. Mechanistically, our results suggest that FGFRs are activated by N-Cadherin. N-Cadherin cell-autonomously binds FGFRs and inhibits FGFR K27- and K29-linked polyubiquitination and lysosomal degradation. Accordingly, FGFRs accumulate and stimulate prolonged Erk1/2 phosphorylation. Neurons inhibited for Erk1/2 are stalled in the multipolar zone. Moreover, Reelin, a secreted protein regulating neuronal positioning, prevents FGFR degradation through N-Cadherin, causing Erk1/2 phosphorylation. These findings reveal novel functions for FGFRs in cortical projection neuron migration, suggest a physiological role for FGFR and N-Cadherin interaction in vivo and identify Reelin as an extracellular upstream regulator and Erk1/2 as downstream effectors of FGFRs during neuron migration.

The Aberrant Expression of the Mesenchymal Variant of FGFR2 in the Epithelial Context Inhibits Autophagy

Signaling of the epithelial splice variant of fibroblast growth factor receptor 2 (FGFR2b) triggers both differentiation and autophagy, while the aberrant expression of the mesenchymal FGFR2c isoform in epithelial cells induces impaired differentiation, epithelial mesenchymal transition (EMT) and tumorigenic features. Here we analyzed in the human keratinocyte cell line, as well as in primary cultured cells, the possible impact of FGFR2c forced expression on the autophagic process. Biochemical and quantitative immunofluorescence analysis, coupled to the use of autophagic flux sensors, specific substrate inhibitors or silencing approaches, showed that ectopic expression and the activation of FGFR2c inhibit the autophagosome formation and that AKT/MTOR is the downstream signaling mainly involved. Interestingly, the selective inhibition of AKT or MTOR substrates caused a reversion of the effects of FGFR2c on autophagy, which could also arise from the imbalance of the interplay between AKT/MTOR pathway and JNK1 signaling in favor of JNK1 activation, BCL-2 phosphorylation and possibly phagophore nucleation. Finally, silencing experiments of depletion of ESRP1, responsible for FGFR2 splicing and consequent FGFR2b expression, indicated that the switching from FGFR2b to FGFR2c isoform could represent the key event underlying the inhibition of the autophagic process in the epithelial context. Our results provide the first evidence of a negative impact of the out-of-context expression of FGFR2c on autophagy, suggesting a possible role of this receptor in the modulation of the recently proposed negative loop between autophagy and EMT during carcinogenesis.

A Phase I, Open-Label, Multicenter, Dose-escalation Study of the Oral Selective FGFR Inhibitor Debio 1347 in Patients with Advanced Solid Tumors Harboring FGFR Gene Alterations

PURPOSE

To investigate tolerability, efficacy, and pharmacokinetics/pharmacodynamics of Debio 1347, a selective FGFR inhibitor.

PATIENTS AND METHODS

This was a first-in-human, multicenter, open-label study in patients with advanced solid tumors harboring FGFR1-3 gene alterations. Eligible patients received oral Debio 1347 at escalating doses once daily until disease progression or intolerable toxicity. Dose-limiting toxicities (DLT) were evaluated during the first 4 weeks on treatment, pharmacokinetics/pharmacodynamics postfirst dose and after 4 weeks.

RESULTS

A total of 71 patients were screened and 58 treated with Debio 1347 at doses from 10 to 150 mg/day. Predominant tumor types were breast and biliary duct cancer, most common gene alterations were FGFR1 amplifications (40%) and mutations in FGFR2 (12%) and FGFR3 (17%); 12 patients (21%) showed FGFR fusions. Five patients at three dose levels had six DLTs (dry mouth/eyes, hyperamylasemia, hypercalcemia, hyperbilirubinemia, hyperphosphatemia, and stomatitis). The maximum tolerated dose was not reached, but dermatologic toxicity became sometimes dose limiting beyond the DLT period at ≥80 mg/day. Adverse events required dose modifications in 52% of patients, mostly due to dose-dependent, asymptomatic hyperphosphatemia (22%). RECIST responses were seen across tumor types and mechanisms of FGFR activation. Six patients, 3 with FGFR fusions, demonstrated partial responses, 10 additional patients' tumor size regressions of ≤30%. Plasma half-life was 11.5 hours. Serum phosphate increased with Debio 1347 plasma levels and confirmed target engagement at doses ≥60 mg/day.

CONCLUSIONS

Preliminary efficacy was encouraging and tolerability acceptable up to 80 mg/day, which is now used in an extension part of the study.

Acquired JHDM1D-BRAF Fusion Confers Resistance to FGFR Inhibition in FGFR2-Amplified Gastric Cancer

FGFR2 gene is frequently amplified in gastric cancer. Recently, targeting FGFR2 has drawn attention as a form of gastric cancer therapy, and FGFR-selective inhibitors have shown promising efficacy in clinical studies. Because overcoming acquired resistance is a common problem with molecular targeting drugs, we investigated a resistant mechanism of FGFR inhibitors using the gastric cancer cell line SNU-16, which harbors FGFR2 amplification. We established single-cell clones of FGFR inhibitor-resistant SNU-16 (AZD-R) by continuous exposure to AZD4547, a selective FGFR inhibitor. To screen the genetic alterations acquired in AZD-R, we ran a comparative genomic hybridization assay and found an amplification of Chr7q34 region. The chromosomal breakpoints were located between the 12th and the 13th exon of jumonji C domain containing histone demethylase 1 homolog D (JHDM1D) and between the 3rd and the 4th exon of BRAF We sequenced cDNA of the AZD-R clones and found fusion kinase JHDM1D-BRAF, which has previously been identified in primary ovarian cancer. Because JHDM1D-BRAF fusion lacks a RAS-binding domain, the dimerization of JHDM1D-BRAF was enhanced. A cell growth inhibition assay using MEK inhibitors and RAF-dimer inhibitors indicated the dependence of AZD-R clones for growth on the MAPK pathway. Our data provide a clinical rationale for using a MEK or RAF dimer inhibitor to treat FGFR2-amplified gastric cancer patients who have acquired resistance through the JHDN1D-BRAF fusion. Mol Cancer Ther; 17(10); 2217-25. ©2018 AACR.

Role of Fibroblast Growth Factor Receptor 2b in the Cross Talk between Autophagy and Differentiation: Involvement of Jun N-Terminal Protein Kinase Signaling

Fibroblast growth factor receptor 2b (FGFR2b) is a receptor tyrosine kinase expressed exclusively in epithelial cells. We previously demonstrated that FGFR2b induces autophagy and that this process is required for the triggering of FGFR2b-mediated early differentiation of keratinocytes. However, the molecular mechanisms regulating this interplay remain to be elucidated. Since we have also recently shown that Jun N-terminal protein kinase 1 (JNK1) signaling is involved in FGFR2b-induced autophagy and a possible role of the JNK pathway in epidermal differentiation has been suggested (though it is still debated), we investigated here the cross talk between FGFR2b-mediated autophagy and differentiation, focusing on the downstream JNK signaling. Biochemical, molecular, and immunofluorescence approaches in 2-dimensional (2-D) keratinocyte cultures and three-dimensional (3-D) organotypic skin equivalents confirmed that FGFR2b overexpression increased both autophagy and early differentiation. The use of FGFR2b substrate inhibitors and the silencing of JNK1 highlighted that this signaling is required not only for autophagy but also for the triggering of early differentiation. In contrast, the extracellular signal-regulated kinase 1 and 2 (ERK1/2) pathway did not appear to be involved in the two processes, and AKT signaling, whose activation contributes to the FGFR2b-mediated onset of keratinocyte differentiation, was not required for the triggering of autophagy. Overall, our results point to JNK1 as a signaling hub that regulates the interplay between FGFR2b-induced autophagy and differentiation.

Blockage of the mevalonate pathway overcomes the apoptotic resistance to MEK inhibitors with suppressing the activation of Akt in cancer cells

With increasing clinical demands for MEK inhibitors in cancer treatment, overcoming the resistance to MEK inhibitors is an urgent problem to be solved. Numerous reports have shown that MEK inhibition results in the activation of PI3K-Akt signaling, which may confer apoptotic resistance to MEK inhibitors. We here demonstrate that the blockade of the mevalonate pathway using the antilipidemic drug statins represses Akt activation following MEK inhibition and induces significant apoptosis when co-treated with CH5126766 or trametinib. These events were clearly negated by the addition of mevalonate or geranylgeranyl pyrophosphate, indicating that the protein geranylgeranylation is implicated in the apoptotic resistance to MEK inhibitors. Furthermore, mechanistically, the combined treatment of CH5126766 with statins upregulated TNF-related apoptosis-inducing ligand (TRAIL), which was dependent on inhibition of the mevalonate pathway and is involved in apoptosis induction in human breast cancer MDA-MB-231 cells. The present study not only revealed that the mevalonate pathway could be targetable to enhance the efficacy of MEK inhibitors, but also proposes that combinatorial treatment of MEK inhibitors with statins may be a promising therapeutic strategy to sensitize cancer cells to apoptosis.

Role of the stromal cell derived factor-1/CXC chemokine receptor 4 axis in the invasion and metastasis of lung cancer and mechanism

Background

Lung cancer is the most common tumor, and has the highest incidence and mortality rates among all malignant tumors. Since stromal cell derived factor-1 (SDF-1) and CXC chemokine receptor 4 (CXCR4) are specific to binding sites, they are more important than other members of the families for tumor invasion and metastasis. We herein aimed to investigate the role of the axis of chemokine SDF-1 and its receptor CXCR4 in the invasion and metastasis of lung cancer.

Methods

Sixty clinical non-small cell lung cancer (NSCLC) tissue samples were collected. The CXCR4 expressions in cancer, paracancerous and normal lung tissues were detected by immunocytochemical assay and PCR. Cells with CXCR4 overexpression (CXCR4-A549) were constructed. After induction with SDF-1, CXCR4-A549 and A549 cells were subjected to in vitro chemotaxis and invasion assays. Their proliferation and apoptosis were detected by flow cytometry. The activities of phosphoinositide 3-kinase/protein kinase B (AKT) and mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK)-related signaling pathways were detected by Western blot. The downstream signaling molecules that may be activated by SDF-1/CXCR4 were analyzed. The expressions of vascular endothelial growth factor-C and matrix metalloproteinase-2 were detected by Western blot and PCR. A mouse model was established by subcutaneous inoculation of lung cancer cells. The effects of up-regulated CXCR4 expression on the migration of lung cancer cells in vitro and their tumorigenesis and metastasis in vivo were assessed.

Results

There was no expression in normal or paracancerous tissues. The expression of CXCR4 mRNA in lung cancer tissues was 83.3% (50/60). The expressions of CXCR4 in lung squamous cell carcinoma and adenocarcinoma were similar (P>0.05). The expression of CXCR4 was 76.9% (10/13) in highly differentiated carcinoma, 82.1% (23/28) in moderately differentiated carcinoma and 84.2% (16/19) in lowly differentiated carcinoma (P>0.05). The expression of CXCR4 was 72.7% (8/11) in TNM stage I patients, 83.9% (26/31) in stage II patients, and 88.9% (16/18) in stage III patients, with significant correlations. After up-regulation of CXCR4, the invasion ability of CXCR4-A549 cells was increased 1.62-fold (P<0.05). ERK and AKT were significantly phosphorylated 30 min after SDF-1 treatment. The tumorigenic rates of six mice inoculated with CXCR4-A549 and A549 cells were both 100%, with the average tumor weights of (4.37±0.96 g) and (3.24±1.16 g) respectively (P<0.05). In the CXCR4-A549 group, metastatic tumors clearly formed in the lungs of 6 mice, but only 2 mice in the A549 group had tumor cell invasion.

Conclusions

SDF-1/CXCR4 played a key role in the invasion and metastasis of lung cancer. The interaction between SDF-1α and CXCR4 activated a series of downstream molecules by activating ERK and AKT.

Interplay between FGFR2b-induced autophagy and phagocytosis: role of PLCγ-mediated signalling

Signalling of the epithelial splicing variant of the fibroblast growth factor receptor 2 (FGFR2b) induces both autophagy and phagocytosis in human keratinocytes. Here, we investigated, in the cell model of HaCaT keratinocytes, whether the two processes might be related and the possible involvement of PLCγ signalling. Using fluorescence and electron microscopy, we demonstrated that the FGFR2b-induced phagocytosis and autophagy involve converging autophagosomal and phagosomal compartments. Moreover, the forced expression of FGFR2b signalling mutants and the use of specific inhibitors of FGFR2b substrates showed that the receptor-triggered autophagy requires PLCγ signalling, which in turn activates JNK1 via PKCδ. Finally, we found that in primary human keratinocytes derived from light or dark pigmented skin and expressing different levels of FGFR2b, the rate of phagocytosis and autophagy and the convergence of the two intracellular pathways are dependent on the level of receptor expression, suggesting that FGFR2b signalling would control in vivo the number of melanosomes in keratinocytes, determining skin pigmentation.

MITF suppression improves the sensitivity of melanoma cells to a BRAF inhibitor

Microphthalmia-associated transcription factor (MITF) is expressed in melanomas and has a critical role in melanocyte development and transformation. Because inhibition of MITF inhibits cell growth in melanoma, MITF is a potential therapeutic target molecule. Here, we report the identification of CH6868398, which has a novel chemical structure and suppresses MITF expression at the protein level in melanoma cells. CH6868398 showed cell growth inhibition activity against MITF-dependent melanoma cells both with and without BRAF mutation and also exhibited anti-tumor efficacy in a melanoma xenograft model. Because selective BRAF inhibitors are standard therapeutics for BRAF-mutated melanoma, we investigated the effect of CH6868398 with a BRAF inhibitor, PLX4720, on cell growth inhibition. The addition of CH6868398 enhanced the cell growth inhibition activity of PLX4720 in melanoma cell lines. Furthermore, combination of CH6868398 and PLX4720 efficiently suppressed MITF protein and enhanced cleavage of Caspase3 and poly (ADP-ribose) polymerase (PARP) in melanoma cell lines. These data support the therapeutic potential of CH6868398 as an anti-melanoma agent that reduces MITF protein levels in combination with BRAF inhibitors.

MITF suppression by CH5552074 inhibits cell growth in melanoma cells

PURPOSE

Although treatment of melanoma with BRAF inhibitors and immune checkpoint inhibitors achieves a high response rate, a subset of melanoma patients with intrinsic and acquired resistance are insensitive to these therapeutics, so to improve melanoma therapy other target molecules need to be found. Here, we screened our chemical library to identify an anti-melanoma agent and examined its action mechanisms to show cell growth inhibition activity.

METHODS

We screened a chemical library against multiple skin cancer cell lines and conducted ingenuity pathway analysis (IPA) to investigate the mechanisms of CH5552074 activity. Suppression of microphthalmia-associated transcription factor (MITF) expression levels was determined in melanoma cells treated with CH5552074. Cell growth inhibition activity of CH5552074 was evaluated in MITF-dependent melanoma cell lines.

RESULTS

We identified an anti-melanoma compound, CH5552074, which showed remarkable cell growth inhibition activity in melanoma cell lines. The IPA results suggested that CH5552074-sensitive cell lines had activated MITF. In further in vitro studies in the melanoma cell lines, a knockdown of MITF with siRNA resulted in cell growth inhibition, which showed that CH5552074 inhibited cell growth by reducing the expression level of MITF protein.

CONCLUSIONS

These results suggest that CH5552074 can inhibit cell growth in melanoma cells by reducing the protein level of MITF. MITF inhibition by CH5552074 would be an attractive option for melanoma treatment.

Identification of Pharmacodynamic Transcript Biomarkers in Response to FGFR Inhibition by AZD4547

The challenge of developing effective pharmacodynamic biomarkers for preclinical and clinical testing of FGFR signaling inhibition is significant. Assays that rely on the measurement of phospho-protein epitopes can be limited by the availability of effective antibody detection reagents. Transcript profiling enables accurate quantification of many biomarkers and provides a broader representation of pathway modulation. To identify dynamic transcript biomarkers of FGFR signaling inhibition by AZD4547, a potent inhibitor of FGF receptors 1, 2, and 3, a gene expression profiling study was performed in FGFR2-amplified, drug-sensitive tumor cell lines. Consistent with known signaling pathways activated by FGFR, we identified transcript biomarkers downstream of the RAS-MAPK and PI3K/AKT pathways. Using different tumor cell lines in vitro and xenografts in vivo, we confirmed that some of these transcript biomarkers (DUSP6, ETV5, YPEL2) were modulated downstream of oncogenic FGFR1, 2, 3, whereas others showed selective modulation only by FGFR2 signaling (EGR1). These transcripts showed consistent time-dependent modulation, corresponding to the plasma exposure of AZD4547 and inhibition of phosphorylation of the downstream signaling molecules FRS2 or ERK. Combination of FGFR and AKT inhibition in an FGFR2-mutated endometrial cancer xenograft model enhanced modulation of transcript biomarkers from the PI3K/AKT pathway and tumor growth inhibition. These biomarkers were detected on the clinically validated nanoString platform. Taken together, these data identified novel dynamic transcript biomarkers of FGFR inhibition that were validated in a number of in vivo models, and which are more robustly modulated by FGFR inhibition than some conventional downstream signaling protein biomarkers. Mol Cancer Ther; 15(11); 2802-13. ©2016 AACR.