MET and Small-Cell Lung Cancer

Evaluation of [18F]AlF-EMP-105 for Molecular Imaging of C-Met

C-Met is a receptor tyrosine kinase that is overexpressed in a range of different cancer types, and has been identified as a potential biomarker for cancer imaging and therapy. Previously, a ⁶⁸Ga-labelled peptide, [⁶⁸Ga]Ga-EMP-100, has shown promise for imaging c-Met in renal cell carcinoma in humans. Herein, we report the synthesis and preliminary biological evaluation of an [¹⁸F]AlF-labelled analogue, [¹⁸F]AlF-EMP-105, for c-Met imaging by positron emission tomography. EMP-105 was radiolabelled using the aluminium-[¹⁸F]fluoride method with 46 ± 2% RCY and >95% RCP in 35-40 min. In vitro evaluation showed that [¹⁸F]AlF-EMP-105 has a high specificity for c-Met-expressing cells. Radioactive metabolite analysis at 5 and 30 min post-injection revealed that [¹⁸F]AlF-EMP-105 has good blood stability, but undergoes transformation-transchelation, defluorination or demetallation-in the liver and kidneys. PET imaging in non-tumour-bearing mice showed high radioactive accumulation in the kidneys, bladder and urine, demonstrating that the tracer is cleared predominantly as [¹⁸F]fluoride by the renal system. With its high specificity for c-Met expressing cells, [¹⁸F]AlF-EMP-105 shows promise as a potential diagnostic tool for imaging cancer.

Overview of Molecular Detection Technologies for MET in Lung Cancer

MET tyrosine kinase receptor pathway activation has become an important actionable target in solid tumors. Aberrations in the MET proto-oncogene, including MET overexpression, the activation of MET mutations, MET mutations that lead to MET exon 14 skipping, MET gene amplifications, and MET fusions, are known to be primary and secondary oncogenic drivers in cancer; these aberrations have evolved as predictive biomarkers in clinical diagnostics. Thus, the detection of all known MET aberrations in daily clinical care is essential. In this review, current molecular technologies for the detection of the different MET aberrations are highlighted, including the benefits and drawbacks. In the future, another focus will be on the standardization of detection technologies for the delivery of reliable, quick, and affordable tests in clinical molecular diagnostics.

Targeting the cMET pathway to enhance immunotherapeutic approaches for mUM patients

The liver is the most preferential initial site of metastasis for uveal melanoma (mUM), and this preference is associated with rapid mortality in mUM patients. Despite the significant clinical benefits of Immune checkpoint inhibitors (ICIs) in metastatic cutaneous melanoma patients, ICIs have shown little to no benefit in mUM patients. A potential reason for this inefficiency of ICI could be partly devoted to the involvement of the liver itself, thanks to its rich source of growth factors and immunosuppressive microenvironment. Uveal melanoma cells show increased expression of a transmembrane protein called cMET, which is known as the sole receptor for the Hepatocyte growth factor (HGF). Hyperactivation of cMET by HGF contributes to mUM development, and the liver, being the major source of HGF, may partially explain the metastasis of uveal melanoma cells to the liver. In addition, cMET/HGF signaling has also been shown to mediate resistance to ICI treatment, directly and indirectly, involving tumor and immune cell populations. Therefore, targeting the cMET/HGF interaction may enhance the efficacy of immunotherapeutic regimes for mUM patients. Hence in this minireview, we will discuss the rationale for combining cMET inhibitors/antibodies with leading immune checkpoint inhibitors for treating mUM. We will also briefly highlight the challenges and opportunities in targeting cMET in mUM.

Synergistic Antitumor Effects of Anlotinib Combined with Oral 5-Fluorouracil/S-1 via Inhibiting Src/AKT Signaling Pathway in Small-Cell Lung Cancer

Background

Small-molecule tyrosine inhibitor anlotinib which developed in China has been approved as a third-line treatment for patients with small-cell lung cancer (SCLC). Our previous clinical study found that anlotinib combined with S-1 has better short-term ORR than the single-agent anlotinib of SCLC and other small-molecule vascular targeted drug therapies in the treatment of SCLC. However, the molecular mechanism of those effect remains unclear.

Methods

SCLC cell line H446 was treated with either anlotinib, 5-FU alone, or combination. The cellular effects including cell viability, cell apoptosis, cell cycle, cell migration, and invasion were explored to evaluate the cell proliferation level. Western blot was performed to determine the protein levels of the combined action of the two drugs. The xenograft mouse model was established by injection of H446 cells into mouse, and the animals were randomized and assigned for the drug treatments. Body weights and tumor sizes were recorded. WB was conducted using tumor tissues. All data were collected and statistically analyzed using t-test to reveal the underlying molecular mechanism.

Results

When anlotinib was combined with 5-FU, the IC50 value of cells was significantly reduced. And apoptosis, cell cycle arrest, and cell motility rates were stronger when anlotinib combined with 5-FU than in the anlotinib or 5-FU alone. In H446 cell-derived xenograft mouse model, tumor volumes were significantly decreased in Anlo/5-FU combination group than anlotinib or 5-FU alone group. Western blot showed the decreasing expression of p-Src/p-AKT in the Anlo/5-FU group.

Conclusion

Our data revealed that the treatment of combination of antitumor angiogenesis agent anlotinib with chemotherapy drug 5-FU may have synergistic cytotoxicity to SCLC in vitro and in vivo. This treatment modality reduced cell proliferation and migration via Src/AKT pathway. This new strategy may be a promising treatment for SCLC but needs to be confirmed in future clinical trials.

Antineoplastic effects of erufosine on small cell and non-small cell lung cancer cells through induction of apoptosis and cell cycle arrest

BACKGROUND

Lung cancer (LC) is the most common types of cancer worldwide and is marked by high mortality rate. LC is classified into two major types due to their molecular and histological properties; non-small cell lung cancer (NSCLC) A549 and small cell lung cancer (SCLC). Currently, surgery, chemotherapy and radiation therapy are the most common treatment options of LC. However, the survival rate of LC is still very poor. Therefore, new treatment strategies are urgently needed. Erufosine (ErPC3) is a novel alkylphosphocholine and inhibits the translocation of Akt to the plasma membrane.

METHODS AND RESULTS

In the current study, the effects of ErPC3 in NSCLC cell line A549 and SCLC cell line DMS 114 in terms of cell viability, induction of apoptosis, cell cycle phase distribution, gene and protein expression levels, and migration capacity were investigated. 25 µM ErPC3 exhibited dose-dependent cytotoxicity against in both cancer cells. However, DMS 114 was more sensitive to ErPC3 than A549. Similarly, ErPC3 induced apoptotic cell ratio in DMS114 was significantly greater than A549. 25 µM ErPC3 caused the accumulation of both cell in G2/M phase. The levels of BCL-2 were downregulated and CASPASE 3-7 and BAX were upregulated while p-Akt levels were reduced in A549 and DMS 114 cells treated with 25 µM ErPC3. Besides, ErPC3 displayed anti-migratory effect on A549 and DMS 114.

CONCLUSION

These findings suggest that ErPC3 may be a promising novel therapeutic candidate for treatment of LC. ErPC3 treatment merits further investigation as potential agent against LC.

Frequency of actionable molecular drivers in lung cancer patients with precocious brain metastases

Brain metastases frequently occur during the course of disease in patients suffering from lung cancer. Occasionally, neurological symptoms caused by brain metastases (BM) might represent the first sign of systemic tumor disease (so called precocious metastases), leading to the detection of the primary lung tumor. The biological basis of precocious BM is largely unknown, and treatment options are not well established for this subgroup of patients. Therefore, we retrospectively analyzed 33 patients (24 non-small cell lung cancer (NSCLC)), 9 small cell lung cancer (SCLC)) presenting with precocious BM focusing on molecular alterations potentially relevant for the tumor's biology and treatment. We found five FGFR1 amplifications (4 adenocarcinoma, 1 SCLC) among 31 analyzed patients (16.1%), eight MET amplifications among 30 analyzed tumors (7 NSCLC, 1 SCLC; 26.7%), three EGFR mutations within 33 patients (all adenocarcinomas, 9.1%), and five KRAS mutations among 32 patients (all adenocarcinomas; 15.6%). No ALK, ROS1 or RET gene rearrangements were detected. Our findings suggest that patients with precocious BM of lung cancer harbor EGFR mutations, MET amplifications or FGFR1 amplifications as potential targeted treatment options.

ARID2 deficiency promotes tumor progression and is associated with higher sensitivity to chemotherapy in lung cancer

The survival rate in lung cancer remains stubbornly low and there is an urgent need for the identification of new therapeutic targets. In the last decade, several members of the SWI/SNF chromatin remodeling complexes have been described altered in different tumor types. Nevertheless, the precise mechanisms of their impact on cancer progression, as well as the application of this knowledge to cancer patient management are largely unknown. In this study, we performed targeted sequencing of a cohort of lung cancer patients on genes involved in chromatin structure. In addition, we studied at the protein level the expression of these genes in cancer samples and performed functional experiments to identify the molecular mechanisms linking alterations of chromatin remodeling genes and tumor development. Remarkably, we found that 20% of lung cancer patients show ARID2 protein loss, partially explained by the presence of ARID2 mutations. In addition, we showed that ARID2 deficiency provokes profound chromatin structural changes altering cell transcriptional programs, which bolsters the proliferative and metastatic potential of the cells both in vitro and in vivo. Moreover, we demonstrated that ARID2 deficiency impairs DNA repair, enhancing the sensitivity of the cells to DNA-damaging agents. Our findings support that ARID2 is a bona fide tumor suppressor gene in lung cancer that may be exploited therapeutically.

Anlotinib Inhibits Cell Proliferation, Migration and Invasion via Suppression of c-Met Pathway and Activation of ERK1/2 Pathway in H446 Cells

BACKGROUND

Small Cell Lung Cancer (SCLC) represents the most aggressive pulmonary neoplasm and is often diagnosed at late stage with limited survival, despite combined chemotherapies. The purpose of this study was to investigate the effect of anlotinib on SCLC and the potential molecular mechanisms.

METHODS

Cell viability was assessed by CCK-8 assay to determine the adequate concentration of anlotinib. Then, effects of anlotinib on cell apoptosis, cell cycle distribution, migration and invasion were analyzed by flow cytometry, PI staining, wound healing assay and transwell assay, respectively. The protein expression of c-met and ERK1/2 pathways in H446 cells were assessed by western blot analysis.

RESULTS

In this study, we found that anlotinib significantly reduced the cell viability of H446 cells, induced G2/M cell cycle arrest and decreased invasion and migration of H446 cells. Futhermore, we also found that anlotinib could suppress c-met signal transduction and activate the ERK1/2 pathway in H446 cells. More importantly, c-met was involved in the effects of anlotinib on migration and invasion in H446 cells.

CONCLUSION

Taken together, our results demonstrated that anlotinib was a potential anticancer agent that inhibited cell proliferation, migration and invasion via suppression of the c-met pathway and activation of the ERK1/2 pathway in H446 cells.

Gray E. Tumour PD-L1 Expression in Small-Cell Lung Cancer: A Systematic Review and Meta-Analysis

Antibodies against programmed death-1 (PD-1), and its ligand, (PD-L1) have been approved recently for the treatment of small-cell lung cancer (SCLC). Although there are previous reports that addressed PD-L1 detection on tumour cells in SCLC, there is no comprehensive meta-analysis on the prevalence of PD-L1 expression in SCLC. We performed a systematic search of the PubMed, Cochrane Library and EMBASE databases to assess reports on the prevalence of PD-L1 expression and the association between PD-L1 expression and overall survival (OS). This meta-analysis included 27 studies enrolling a total of 2792 patients. The pooled estimate of PD-L1 expression was 26.0% (95% CI 17.0–37.0), (22.0% after removing outlying studies). The effect size was significantly heterogeneous (I² = 97.4, 95% CI: 95.5–98.5, p < 0.0001).Positive PD-L1 expression was a favourable prognostic factor for SCLC but not statistically significant (HR = 0.86 (95% CI (0.49–1.50), p = 0.5880; I² = 88.7%, p < 0.0001). Begg’s funnel plots and Egger’s tests indicated no publication bias across included studies (p > 0.05). Overall, there is heterogeneity in the prevalence of PD-L1 expression in SCLC tumour cells across studies. This is significantly moderated by factors such as immunohistochemistry (IHC) evaluation cut-off values, and assessment of PD-L1 staining patterns as membranous and/or cytoplasmic. There is the need for large size, prospective and multicentre studies with well-defined protocols and endpoints to advance the clinical value of PD-L1 expression in SCLC.

Identification of nicotinic acetylcholine receptor subunits in different lung cancer cell lines and the inhibitory effect of alpha-conotoxin TxID on lung cancer cell growth

Lung cancer is an aggressive tumor with high incidence and mortality rate. There was growing evidence supporting that nicotinic acetylcholine receptors (nAChRs) play vital role inlung cancer development. In this study, the expression of α3, α4, α5, α6, α7, α9, α10, β2, β3, β4 nAChR subunits on protein and mRNA level were studied in A549, NCI-H1299, NCI-H1688, DMS114 and normal human embryonic lung fibroblast (HEL) cell lines by real-time quantitative PCR (qPCR) and Western blot assay respectively. The results indicated that most of these nAChR subunits were expressed in these five cell lines. Compared with normal cells, the expression of α3 and β4 nAChR subunits were upregulated in A549 and NCI-H1299. Thus, we treated A549 and NCI-H1299 with an antagonist α-conotoxin TxID which potently and selectively blocks α3β4 nAChRs. TxID treatment could inhibit A549 and NCI-H1299 cell growth and enhance the inhibitory effect of adriamycin when treated simultaneously. To sum up, our study identified the expression of nAChR subunits in different lung cells and the anti-tumor effect of α-conotoxin TxID, which may provide novel strategies for lung cancer therapy.

Significance of PD-L1 clones and C-MET expression in hepatocellular carcinoma

Programmed cell death ligand 1 (PD-L1) is an essential immune checkpoint protein implicated in immune evasion by malignant tumors. Overexpression of programmed cell death protein 1 (PD-1) and its ligand PD-L1 is associated with poor prognosis in various types of cancer. Recently, multiple advances have occurred in the area of cancer immunotherapy. Inhibiting the ligation of PD-1 by PD-L1 has been the major focus of anti-tumor immunotherapy. In diagnostic pathology, it has become crucial to detect PD-L1⁺ tumor cases using a validated immunohistochemistry (IHC) approach. Preliminary data demonstrate that C-MET promotes survival of some (e.g., renal) cancer types through regulation of PD-L1. However, C-MET expression, and its association with PD-L1, has not been well-characterized in the context of hepatocellular carcinoma (HCC), and no anti-HCC immunotherapy is currently available in Korea. Therefore, it is crucial to investigate the expression of C-MET and PD-L1, and their association with clinicopathologic factors, to facilitate the development of targeted treatments for HCC. PD-L1 expression was examined in tumor cells (TC) and immune cells (IC) of 70 patient-derived HCC specimens using IHC. Two anti-PD-L1 monoclonal antibodies (MAbs), SP263 and SP142, were utilized. Additionally, TC C-MET expression was assessed. Correlations between PD-L1 expression (as identified by both MAbs), C-MET expression and clinicopathologic factors were assessed. More PD-L1⁺ cases were identified via SP263 than via SP142 when assessing both TC and IC; in the former group, SP236 identified 14/70 positive cases, while SP142 identified only 2/70. In the latter group, SP236 identified 49/70 positive cases, while SP142 identified 30/70. Both MAbs demonstrated a higher frequency of PD-L1 expression by IC than TC. The Edmondson-Steiner grade statistically correlated with a higher frequency of SP236-detected TC PD-L1 expression. C-MET was significantly associated with advanced tumor size and was positively correlated with SP263-detected PD-L1 expression in TC. These results suggest that C-MET may serve a role in regulating PD-L1 expression in HCC. Furthermore, while SP263 generally exhibited a higher sensitivity for PD-L1 detection, concordance in PD-L1⁺ case detection between the two different MAbs was generally good. These background data may be helpful in the development of targeted anti-HCC immunotherapy focused on PD-L1 or C-MET, and in evaluating selection criteria for target populations best suited to such treatments.

The roles of tumor-derived exosomes in non-small cell lung cancer and their clinical implications

Non-small cell lung cancer (NSCLC) accounts for approximately 85% of lung cancer cases, and it is one of the leading causes of cancer death in both men and women worldwide due to diagnosis in the advanced stage, rapid metastasis, and recurrence. At present, precision molecular targeted therapeutics directed toward NSCLC driven genes has made great progress and significantly improved the overall survival of patients with NSCLC, but can easily lead to acquired drug resistance. New methods are needed to develop real-time monitoring of drug efficacy and drug resistance, such as new molecular markers for more effective early detection and prediction of prognosis. Exosomes are nano-sized extracellular vesicles, containing proteins, nucleic acids and lipids, which are secreted by various cells, and they play an important role in the development of lung cancer by controlling a wide range of pathways. Tumor-derived exosomes are of great significance for guiding the targeted therapy of NSCLC and exosomes themselves can be a target for treatment. In this review, we describe the potential roles of tumor-derived exosomes and their clinical significance in NSCLC.

Hsa-miR-329 exerts tumor suppressor function through down-regulation of MET in non-small cell lung cancer

MicroRNAs (miRNAs) act as key regulators of multiple cancers. Hsa-miR-329 (miR-329) functions as a tumor suppressor in some malignancies. However, its role on lung cancer remains poorly understood. In this study, we investigated the role of miR-329 on the development of lung cancer. The results indicated that miR-329 was decreased in primary lung cancer tissues compared with matched adjacent normal lung tissues and very low levels were found in a non-small cell lung cancer (NSCLC) cell lines. Ectopic expression of miR-329 in lung cancer cell lines substantially repressed cell growth as evidenced by cell viability assay, colony formation assay and BrdU staining, through inhibiting cyclin D1, cyclin D2 and up-regulatiing p57(Kip2) and p21(WAF1/CIP1). In addition, miR-329 promoted NSCLC cell apoptosis, as indicated by up-regulation of key apoptosis gene cleaved caspase-3, and down-regulation of anti-apoptosis gene Bcl2. Moreover, miR-329 inhibited cellular migration and invasiveness through inhibiting matrix metalloproteinases (MMP)-7 and MMP-9. Further, oncogene MET was revealed to be a putative target of miR-329, which was inversely correlated with miR-329 expression. Furthermore, down-regulation of MET by siRNA performed similar effects to over-expression of miR-329. Collectively, our results demonstrated that miR-329 played a pivotal role in lung cancer through inhibiting cell proliferation, migration, invasion, and promoting apoptosis by targeting oncogenic MET.

Interactions of quercetin with receptor tyrosine kinases associated with human lung carcinoma

Lung cancer is a deadly form of cancer with high morbidity and mortality rates. Deregulated receptor tyrosine kinases (RTKs) are frequently associated with the formation and development of lung carcinoma. Quercetin is a major dietary flavonoid that has been shown to induce cell growth inhibition and apoptosis in human lung cancer cell lines. In the current study, four major overexpressed RTKs - EGFR, FGFR1, IGF1R and c-Met - involved in human lung cancer were investigated. Molecular docking was employed to identify the binding orientation and inhibitory potential of quercetin in these RTKs. Quercetin bound to the ATP binding pocket of these kinases exhibited good binding scores and interactions by establishing hydrogen, hydrophobic and π-π interactions with the hinge region and the DFG motif in the activation loop. Thus, quercetin could be further explored as a platform for developing specific or polypharmacological compounds targeting overexpressed RTKs in lung cancer.

Clinical impact of high serum hepatocyte growth factor in advanced non-small cell lung cancer

Activation of c-MET through hepatocyte growth factor (HGF) increases tumorigenesis, induces resistance, and is associated with poor prognosis in various solid tumors. However, the clinical value of serum HGF (sHGF) in patients with advanced non-small cell lung cancer (NSCLC), especially those receiving cytotoxic chemotherapy, remains unknown. Here, we show that sHGF may be useful to predict tumor response and progression-free survival (PFS) in patients with advanced NSCLC. A total of 81 patients with NSCLC were investigated. sHGF levels were evaluated using ELISA at 4 time-points: at pre-treatment, at response-evaluation (1-2 months after treatment initiation), at the best tumor response, and at disease progression. As a control biomarker, CEA was also evaluated in lung adenocarcinoma. Positive-sHGF at response-evaluation predicted poor PFS compared with Negative-sHGF in both first-line (median, 153.5 vs. 288.0; P < 0.05) and second-line treatment (87.0 vs. 219.5; P = 0.01). In 55 patients that received cytotoxic chemotherapy, multiple Cox proportional hazards models showed significant independent associations between poor PFS and Positive-sHGF at response-evaluation (hazard ratio, 4.24; 95% CI, 2.05 to 9.46; P < 0.01). Lung adenocarcinoma subgroup analysis showed that in patients receiving second cytotoxic chemotherapy, there were no significant differences in PFS between patients with low-CEA compared with those with high-CEA, but Positive-sHGF at pre-treatment or at response-evaluation predicted poor PFS (35.0 vs. 132.0; P < 0.01, 50.0 vs. 215.0; P < 0.01, respectively). These findings give a rationale for future research investigating the merit of sHGF as a potential clinical biomarker to evaluate HGF/c-MET activity, which would be useful to indicate administration of c-MET inhibitors.

Expression of c-Met and hepatocyte growth factor in various gastric pathologies and its association with Helicobacter pylori infection

Activation of the hepatocyte growth factor (HGF)/c-Met signaling pathway was identified to be associated with malignant tumors. The present study aimed at determining the expression of HGF and c-Met in gastric carcinogenesis and its association with Helicobacter pylori infection. Gastric biopsies were obtained from 160 H. pylori-negative and -positive patients, including those with chronic gastritis, intestinal metaplasia, dysplasia and gastric cancer (GC). Proteins were extracted from GES-1, gastric epithelial, and AGS, gastric adenocarcinoma, cells following co-culture with H. pylori in vitro. The expression of HGF and c-Met in gastric tissues or cells was determined using immunohistochemistry and western blot analysis. The expression of c-Met increased in GC tissues (72.5%) compared with that in pre-cancerous lesions (17.5, 17.5 and 30%). Additional analysis identified that the expression of HGF and c-Met was significantly increased in the presence of H. pylori infection in dysplasia and gastric cancer samples. Furthermore, H. pylori may activate the HGF/c-Met signaling pathway in vitro, which may contribute to gastric carcinogenesis.

Targeting AXL and mTOR Pathway Overcomes Primary and Acquired Resistance to WEE1 Inhibition in Small-Cell Lung Cancer

Purpose: Drugs targeting DNA repair and cell-cycle checkpoints have emerged as promising therapies for small-cell lung cancer (SCLC). Among these, the WEE1 inhibitor AZD1775 has shown clinical activity in a subset of SCLC patients, but resistance is common. Understanding primary and acquired resistance mechanisms will be critical for developing effective WEE1 inhibitor combinations.Experimental Design: AZD1775 sensitivity in SCLC cell lines was correlated with baseline expression level of 200 total or phosphorylated proteins measured by reverse-phase protein array (RPPA) to identify predictive markers of primary resistance. We further established AZD1775 acquired resistance models to identify mechanism of acquired resistance. Combination regimens were tested to overcome primary and acquired resistance to AZD1775 in in vitro and in vivo SCLC models.Results: High-throughput proteomic profiling demonstrate that SCLC models with primary resistance to AZD1775 express high levels of AXL and phosphorylated S6 and that WEE1/AXL or WEE1/mTOR inhibitor combinations overcome resistance in vitro and in vivo Furthermore, AXL, independently and via mTOR, activates the ERK pathway, leading to recruitment and activation of another G2-checkpoint protein, CHK1. AZD1775 acquired resistance models demonstrated upregulation of AXL, pS6, and MET, and resistance was overcome with the addition of AXL (TP0903), dual-AXL/MET (cabozantinib), or mTOR (RAD001) inhibitors.Conclusions: AXL promotes resistance to WEE1 inhibition via downstream mTOR signaling and resulting activation of a parallel DNA damage repair pathway, CHK1. These findings suggest rational combinations to enhance the clinical efficacy of AZD1775, which is currently in clinical trials for SCLC and other malignancies. Clin Cancer Res; 23(20); 6239-53. ©2017 AACR.

Downregulation of USP32 inhibits cell proliferation, migration and invasion in human small cell lung cancer

OBJECTIVES

Ubiquitin specific protease 32 (USP32) is a highly conserved but uncharacterized gene, which has been reported to be associated with growth of breast cancer cells. However, the role of USP32 in human small cell lung cancer (SCLC) has not been uncovered. The aim of this study was to investigate and evaluate the clinical significance of USP32 in patients with SCLC.

MATERIALS AND METHODS

Expression of USP32 was firstly investigated using public online data sets and then determined in SCLC tissues and cell lines using quantitative real-time PCR, Western blotting and immunohistochemical staining. SCLC cells were transfected with a small-interfering RNA targeting USP32 mRNA and analysed for cell viability, proliferation ability, cell cycle distribution, apoptosis and invasion.

RESULTS

USP32 was found to be overexpressed in SCLC tissues compared with normal tissues. High USP32 expression was significantly correlated with disease stage and invasion. In vitro experiments demonstrated that silencing of USP32 caused a significant decrease in the proliferation and migration rate of cells. Furthermore, USP32 silencing arrested cell cycle progression at G0/G1 phase via decreasing CDK4/Cyclin D1 complex and elevating p21. In addition, downregulation of USP32 significantly induced cell apoptosis by activating cleaved caspase-3 and cleaved PARP, as well as inhibiting cell invasiveness via altering epithelial mesenchymal transition expression.

CONCLUSIONS

Our results suggest for the first time that USP32 is important for SCLC progression and might be a potential target for molecular therapy of SCLC.

PD-L1 and c-MET expression and survival in patients with small cell lung cancer

BACKGROUND

Blocking the binding between the PD-1 and PD-L1 has been reported to produce antitumor responses. The MET/HGF axis appears to be another signaling pathway frequently altered in small cell lung cancer (SCLC). Our study was aimed to investigate the expression and prognostic roles of PD-L1 and c-MET in SCLC.

METHODS

The expression levels of PD-L1 and c-MET were evaluated by immunohistochemical analysis in 83 SCLC specimens. Survival analysis was performed using the Kaplan-Meier method.

RESULTS

Of the SCLC specimens, 51.8% and 25.3% exhibited positivity for PD-L1 and c-MET, respectively. Higher PD-L1 expression in tumor specimens was significantly correlated with a limited disease (LD) stage, normal levels of serum lactate dehydrogenase (LDH) and neuron-specific enolase (NSE). No association was found between the levels of c-MET and PD-L1 expression or between c-MET expression and other clinical characteristics. SCLC patients with PD-L1-positive tumors showed significantly longer overall survival (OS) than patients with PD-L1-negative tumors (17.0 vs 9.0, p=0.018). Conversely, those with positive c-MET expression exhibited a shorter OS trend (12.0 vs 15.0, p=0.186). However, sub-analysis of LD-stage patients revealed longer OS among the c-MET-negative group (25.0 vs 14.0; p=0.011). The OS of patients with positivity for both PD-L1 and c-MET showed no significant difference compared with other patients (p=0.17). According to multivariate analyses, neither PD-L1 nor c-MET immunoreactivity was a prognostic factor.

CONCLUSION

Expression of PD-L1 was correlated with LD stage and might serve as a prognostic for better OS in SCLC patients. In LD-stage patients, high c-MET expression might be predictive of a poor outcome.

MicroRNA-1 properties in cancer regulatory networks and tumor biology

Short non-coding microRNAs have been identified to orchestrate crucial mechanisms in cancer progression and treatment resistance. MicroRNAs are involved in posttranscriptional modulation of gene expression and therefore represent promising targets for anticancer therapy. As mircoRNA-1 (miR-1) exerted to be predominantly downregulated in the majority of examined tumors, miR-1 is classified to be a tumor suppressor with high potential to diminish tumor development and therapy resistance. Here we review the complex functionality of miR-1 in tumor biology.

New application of an old drug: Antitumor activity and mechanisms of doxycycline in small cell lung cancer

Small cell lung cancer (SCLC) remains one of the most aggressive tumors with a poor prognosis. The clinical outcome of SCLC patients has reached its plateau with the existing standard treatment and thus new therapies are urgently required. Accumulating evidences have indicated that doxycycline, a commonly used antibiotic, has antitumor activity against several malignancies. However, whether doxycycline has antitumor activity in SCLC and its underlying mechanisms remain unclear. Our investigation demonstrated that doxycycline could significantly inhibit the proliferation and colony formulation of SCLC cells (p<0.05). Furthermore, both Hoechst 33258 dye staining and TUNEL assays indicated that doxycycline could induce remarkable apoptosis of H446 cells in a concentration-dependent manner. RT-PCR and western blot assays proved that apoptosis induction effect of doxycycline was achieved via inducing the expression of caspase-3 and bax, as well as attenuating the expression of survivin and bcl-2. Moreover, the wound healing assay and Transwell assay indicated that doxycycline could significantly suppress the migration and invasion of H446 cells in a concentration-dependent manner (p<0.05). ELISA assay proved that the inhibitory effect of doxycycline on the migration and invasion of H446 cells was achieved via decreasing the secretion of MMP-2, MMP-9 and VEGF, as well as increasing the secretion of TIMP-2. Taken together, doxycycline dose-dependently suppressed the proliferation, colony formulation, migration and invasion of SCLC cells, as well as induced apoptosis. These findings encourage further investigations on the potential of doxycycline as a candidate drug for the treatment of SCLC.

Hsa-miR-139-5p inhibits proliferation and causes apoptosis associated with down-regulation of c-Met

Hsa-miRNA-139-5p (miR-139-5p) has recently been discovered having anticancer efficacy in different organs. However, the role of miR-139-5p on lung cancer is still ambiguous. In this study, we investigated the role of miR-139-5p on development of lung cancer. Results indicated miR-139-5p was significantly down-regulated in primary tumor tissues and very low levels were found in a non-small cell lung cancer (NSCLC) cell lines. Ectopic expression of miR-139-5p in NSCLC cell lines significantly suppressed cell growth through inhibition of cyclin D1 and up-regulation of p57(Kip2). In addition, miR-139-5p induced apoptosis, as indicated by up-regulation of key apoptosis gene cleaved caspase-3, and down-regulation of anti-apoptosis gene Bcl2. Moreover, miR-139-5p inhibited cellular metastasis through inhibition of matrix metalloproteinases (MMP)-7 and MMP-9. Further, oncogene c-Met was revealed to be a putative target of miR-139-5p, which was inversely correlated with miR-139-5p expression. Taken together, our results demonstrated that miR-139-5p plays a pivotal role in lung cancer through inhibiting cell proliferation, metastasis, and promoting apoptosis by targeting oncogenic c-Met.

c-Met as a Target for Personalized Therapy

MET and its ligand HGF are involved in many biological processes, both physiological and pathological, making this signaling pathway an attractive therapeutic target in oncology. Downstream signaling effects are transmitted via mitogen-activated protein kinase (MAPK), PI3K (phosphoinositide 3-kinase protein kinase B)/AKT, signal transducer and activator of transcription proteins (STAT), and nuclear factor-κB. The final output of the terminal effector components of these pathways is activation of cytoplasmic and nuclear processes leading to increases in cell proliferation, survival, mobilization and invasive capacity. In addition to its role as an oncogenic driver, increasing evidence implicates MET as a common mechanism of resistance to targeted therapies including EGFR and VEGFR inhibitors. In the present review, we summarize the current knowledge on the role of the HGF-MET signaling pathway in cancer and its therapeutic targeting (HGF activation inhibitors, HGF inhibitors, MET antagonists and selective/nonselective MET kinase inhibitors). Recent advances in understanding the role of this pathway in the resistance to current anticancer strategies used in lung, kidney and pancreatic cancer are discussed.

c-Met as a Target for Personalized Therapy

MET and its ligand HGF are involved in many biological processes, both physiological and pathological, making this signaling pathway an attractive therapeutic target in oncology. Downstream signaling effects are transmitted via mitogen-activated protein kinase (MAPK), PI3K (phosphoinositide 3-kinase protein kinase B)/AKT, signal transducer and activator of transcription proteins (STAT), and nuclear factor-κB. The final output of the terminal effector components of these pathways is activation of cytoplasmic and nuclear processes leading to increases in cell proliferation, survival, mobilization and invasive capacity. In addition to its role as an oncogenic driver, increasing evidence implicates MET as a common mechanism of resistance to targeted therapies including EGFR and VEGFR inhibitors. In the present review, we summarize the current knowledge on the role of the HGF-MET signaling pathway in cancer and its therapeutic targeting (HGF activation inhibitors, HGF inhibitors, MET antagonists and selective/nonselective MET kinase inhibitors). Recent advances in understanding the role of this pathway in the resistance to current anticancer strategies used in lung, kidney and pancreatic cancer are discussed.

Down-regulation of c-Met and Bcl2 by microRNA-206, activates apoptosis, and inhibits tumor cell proliferation, migration and colony formation

Hsa-miRNA-206 (miR-206), highly expressed in skeletal muscle, has recently been discovered to have anticancer properties in different tissues. However, the role of miR-206 on lung cancer is still ambiguous. In this study, we investigated the role of miR-206 on the development of lung cancer. The results indicated that miR-206 expression was suppressed in lung cancer tissues and very low levels were found in non-small cell lung cancer (NSCLS) cell liness. Transient transfection of miR-206 into cultured A549 and SK-MES-1 cells led to significant decrease in cell growth, migration, invasion and colony formation, and promoted cell apoptosis. Using bioinformatics, we identified putative miR-206 binding sites within the 3′-untranslated region (3′-UTR) of the human c-Met and Bcl2 mRNA. The expression of c-Met and Bcl2 proteins were shown to be down-regulated after treated with miR-206 by subsequent Western blot and qRT-PCR analysis. Conversely, up-regulation of c-Met and Bcl2 were confirmed in tissue samples of human lung cancer, with its level inversely correlated with miR-206 expression. In addition, miR-206 also decreased the gene expression of MMP-9, CCND1 and CCND2 while increased the gene expression of p57 (Kip2) in A549 and SK-MES-1 cells. Taken together, our results demonstrated that miR-206 suppressed c-Met and Bcl2 expression in NSCLS and could function as a potent tumor suppressor in c-Met/Bcl2-over expressing tumors. Inhibition of miR-206 function could contribute to aberrant cell proliferation, migration, invasion and apoptosis, leading to NSCLS development.

Regulation of metastatic ability and drug resistance in pulmonary adenocarcinoma by matrix rigidity via activating c-Met and EGFR

Lung fibrosis is a poor prognostic factor for pulmonary adenocarcinoma, and the effect of a rigid microenvironment on cancer behavior is unclear. We cultured A549 cells on matrices of 0.2, 2, and 25 kPa to mimic the rigidities of normal lung parenchyma, progressive fibrotic change, and lung fibrosis, respectively. Lung tissue from patients with pulmonary adenocarcinoma was used to confirm the in vitro findings. Increased matrix rigidity promoted cell proliferation and upregulated the epidermal growth factor receptor (EGFR), hepatocyte growth factor receptor (c-Met), and Snail expression in A549 cells. A549 cells became more resistant to the EGFR inhibitor (Erlotinib) and c-Met inhibitor (PHA-665752) when matrix rigidity increased; however, a high concentration of PHA-665752 reversed the rigidity-induced morphological pleomorphism. In human lung tissue, expression of type I collagen was more consistent with clinical fibrosis than the expression of alpha-smooth muscle antibody was. c-Met- and Snail-expressing tumor cells, rather than EGFR-experssing cells, were localized with lung parenchyma rich in type I collagen. Our findings suggest that c-Met causes the rigidity-induced biophysical reaction in pulmonary adenocarcinoma. Treatment targeting both EGFR and c-Met should be considered for patients with lung fibrosis and who are abundant type I collagen expression in the tumor mass.

FDA-approved small-molecule kinase inhibitors

Kinases have emerged as one of the most intensively pursued targets in current pharmacological research, especially for cancer, due to their critical roles in cellular signaling. To date, the US FDA has approved 28 small-molecule kinase inhibitors, half of which were approved in the past 3 years. While the clinical data of these approved molecules are widely presented and structure-activity relationship (SAR) has been reported for individual molecules, an updated review that analyzes all approved molecules and summarizes current achievements and trends in the field has yet to be found. Here we present all approved small-molecule kinase inhibitors with an emphasis on binding mechanism and structural features, summarize current challenges, and discuss future directions in this field.

Gene of the month: MET

The MET receptor tyrosine kinase and its ligand hepatocyte growth factor/scatter factor (HGF/SF) are potential therapeutic targets in many human malignancies, making this pathway an important focus of molecular and cancer research. MET mutations have been detected in various tumours. In addition, many tumour types demonstrate MET and HGF/SF overexpression and amplification. The MET signal transduction cascade is complex, and manifests in a broad spectrum of mitogenic and morphogenic functions, affecting cell proliferation, migration, differentiation, morphology and survival. Cancer cells commandeer the physiological functions of this signalling axis to facilitate invasion and metastasis. Significant progress has been made in the development of agents that inhibit MET-HGF/SF signalling. In this article, we outline the key features of the MET gene, its protein product and the ligand HGF/SF, to provide an overview of this important signalling pathway and offer a summary of the relevant pathological and clinical directions of research.