Does hepatocyte growth factor/c-Met signal play synergetic role in lung cancer?

The role of α7-nAChR-mediated PI3K/AKT pathway in lung cancer induced by nicotine

Nicotine enters the environment mainly through human activity, as well as natural sources. This review article examines the increasing evidence implicating nicotine in the initiation and progression of lung cancer. Moreover, it primarily focuses on elucidating the activation mechanism of phosphoinositide 3-kinase (PI3K)/protein kinase B (PKB, also known as AKT) signaling pathway, regulated by α7 subtype nicotinic acetylcholine receptor (α7-nAChR), in relation to the proliferation, invasion, and metastasis of lung cancer cells induced by nicotine, as well as nicotine-mediated anti-apoptotic effects. This process involves PI3K/AKT phosphorylated-B-cell lymphoma-2 (Bcl-2) family proteins, PI3K/AKT/mammalian target of rapamycin (mTOR), PI3K/AKT/nuclear factor-κB (NF-κB), hepatocyte growth factor (HGF)/cellular-mesenchymal epithelial transition factor (c-Met)-induced PI3K/AKT and PI3K/AKT activated-hypoxia-inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) pathways. In addition, we also deliberated on the related challenges and upcoming prospects within this field. These lay the foundation for further study on nicotine, lung tumorigenesis, and PI3K/AKT related molecular mechanisms. This work has the potential to significantly contribute to the treatment and prognosis of gastric cancer in smokers. Besides, the crucial significance of PI3K/AKT signaling pathway in multiple molecular pathways also suggests that its target antagonists may inhibit the development and progression of lung cancer, providing a possible new perspective for solving the problem of nicotine-promoted lung cancer. The emerging knowledge about the carcinogenic mechanisms of nicotine action should be considered during the environmental assessment of tobacco and other nicotine-containing products.

Roles of MET in human cancer

The MET proto-oncogene was first identified in osteosarcoma cells exposed to carcinogens. Although expressed in many normal cells, MET is overexpressed in many human cancers. MET is involved in the initiation and development of various human cancers and mediates proliferation, migration and invasion. Accordingly, MET has been successfully used as a biomarker for diagnosis and prognosis, survival, post-operative recurrence, risk assessment and pathologic grading, as well as a therapeutic target. In addition, recent work indicates that inhibition of MET expression and function has potential clinical benefit. This review summarizes the role, mechanism, and clinical significance of MET in the formation and development of human cancer.

Drug combination screening as a translational approach toward an improved drug therapy for chordoma

PURPOSE

Drug screening programmes have revealed epidermal growth factor receptor inhibitors (EGFRis) as promising therapeutics for chordoma, an orphan malignant bone tumour, in the absence of a known genetic driver. Concurrently, the irreversible EGFRi afatinib (Giotrif®) is being evaluated in a multicentric Phase II trial. As tyrosine kinase inhibitor (TKI) monotherapies are invariably followed by resistance, we aimed to evaluate potential therapeutic combinations with EGFRis.

METHODS

We screened 133 clinically approved anticancer drugs as single agents and in combination with two EGFRis (afatinib and erlotinib) in the clival chordoma cell line UM-Chor1. Synergistic combinations were analysed in a 7 × 7 matrix format. The most promising combination was further explored in clival (UM-Chor1, MUG-CC1) and sacral (MUG-Chor1, U-CH1) chordoma cell lines. Secretomes were analysed for receptor tyrosine kinase ligands (EGF, TGF-α, FGF-2 and VEGF-A) upon drug treatment.

RESULTS

Drugs that were active as single agents (n = 45) included TKIs, HDAC and proteasome inhibitors, and cytostatic drugs. Six combinations were analysed in a matrix format: n = 4 resulted in a significantly increased cell killing (crizotinib, dabrafenib, panobinostat and doxorubicin), and n = 2 exhibited no or negligible effects (regorafenib, venetoclax). Clival chordoma cell lines were more responsive to combined EGFR-MET inhibition. EGFR-MET cross-talk (e.g. via TGF-α secretion) likely accounts for the synergistic effects of EGFR-MET inhibition.

CONCLUSION

Our screen revealed promising combinations with EGFRis, such as the ALK/MET-inhibitor crizotinib, the HDAC-inhibitor panobinostat or the topoisomerase-II-inhibitor doxorubicin, which are part of standard chemotherapy regimens for various bone and soft-tissue sarcomas.

MET-EGFR dimerization in lung adenocarcinoma is dependent on EGFR mtations and altered by MET kinase inhibition

Advanced lung cancer has poor survival with few therapies. EGFR tyrosine kinase inhibitors (TKIs) have high response rates in patients with activating EGFR mutations, but acquired resistance is inevitable. Acquisition of the EGFR T790M mutation causes over 50% of resistance; MET amplification is also common. Preclinical data suggest synergy between MET and EGFR inhibitors. We hypothesized that EGFR-MET dimerization determines response to MET inhibition, depending on EGFR mutation status, independently of MET copy number. We tested this hypothesis by generating isogenic cell lines from NCI-H1975 cells, which co-express L858R and T790M EGFR mutations, namely H1975L858R/T790M (EGFR TKI resistant); H1975L858R (sensitized) and H1975WT (wild-type). We assessed cell proliferation in vitro and tumor growth/stroma formation in derived xenograft models in response to a MET TKI (SGX523) and correlated with EGFR-MET dimerization assessed by Förster Resonance Energy Transfer (FRET). SGX523 significantly reduced H1975L858R/T790M cell proliferation, xenograft tumor growth and decreased ERK phosphorylation. The same was not seen in H1975L858R or H1975WT cells. SGX523 only reduced stroma formation in H1975L858R. SGX523 reduced EGFR-MET dimerization in H1975L858R/T790M but induced dimer formation in H1975L858R with no effect in H1975WT. Our data suggests that MET inhibition by SGX523 and EGFR-MET heterodimerisation are determined by EGFR genotype. As tumor behaviour is modulated by this interaction, this could determine treatment efficacy.

Gene mutation-based and specific therapies in precision medicine

Precision medicine has been initiated and gains more and more attention from preclinical and clinical scientists. A number of key elements or critical parts in precision medicine have been described and emphasized to establish a systems understanding of precision medicine. The principle of precision medicine is to treat patients on the basis of genetic alterations after gene mutations are identified, although questions and challenges still remain before clinical application. Therapeutic strategies of precision medicine should be considered according to gene mutation, after biological and functional mechanisms of mutated gene expression or epigenetics, or the correspondent protein, are clearly validated. It is time to explore and develop a strategy to target and correct mutated genes by direct elimination, restoration, correction or repair of mutated sequences/genes. Nevertheless, there are still numerous challenges to integrating widespread genomic testing into individual cancer therapies and into decision making for one or another treatment. There are wide‐ranging and complex issues to be solved before precision medicine becomes clinical reality. Thus, the precision medicine can be considered as an extension and part of clinical and translational medicine, a new alternative of clinical therapies and strategies, and have an important impact on disease cures and patient prognoses.

Cross-talk between MET and EGFR in non-small cell lung cancer involves miR-27a and Sprouty2

In the past decade, we have observed exciting advances in lung cancer therapy, including the development of targeted therapies. However, additional strategies for early detection and tumor-based therapy are still essential in improving patient outcomes. EGF receptor (EGFR) and MET (the receptor tyrosine kinase for hepatocyte growth factors) are cell-surface tyrosine kinase receptors that have been implicated in diverse cellular processes and as regulators of several microRNAs (miRNAs), thus contributing to tumor progression. Here, we demonstrate a biological link between EGFR, MET, and the miRNA cluster 23a ~ 27a ~ 24-2. We show that miR-27a regulates MET, EGFR, and Sprouty2 in lung cancer. In addition, we identify both direct and indirect mechanisms by which miR-27a can regulate both MET and EGFR. Thus, we propose a mechanism for MET and EGFR axis regulation that may lead to the development of therapeutics in lung cancer.

Targeting the Met pathway in lung cancer

Dysregulation of Met signaling has been implicated in the initiation, progression and metastasis of human cancers, and therefore represents an attractive target for anticancer drug development. Met is overexpressed in non-small-cell lung cancer and its lack of staining in normal lung tissue makes it an attractive target. To date, erlotinib and gefitinib have established themselves as first-line therapy for non-small-cell lung cancer patients whose tumors harbor an EGF receptor gene mutation, and hence, it is crucial that we identify mechanisms of resistance that could be targeted by novel agents, while keeping an acceptable toxicity profile at the same time; something very important when we develop these new drugs. Inhibitors of the Met pathway represent a therapeutic alternative in this setting. In this review, we discuss the early clinical studies reported using two Met inhibitors, a monoclonal antibody (MetMAb) and a small molecule tyrosine kinase inhibitor (MGCD265).

Potential mechanism of interleukin-8 production from lung cancer cells: an involvement of EGF-EGFR-PI3K-Akt-Erk pathway

Tumor inflammatory microenvironment is considered to play the role in the sensitivity of tumor cells to therapies and prognosis of lung cancer patients. Interleukin-8 (IL-8) is one of critical chemo-attractants responsible for leukocyte recruitment, cancer proliferation, and angiogenesis. The present study aimed at investigating potential mechanism of IL-8 production from human non-small cell lung cancer (NSCLC) SPC-A1 cells. We initially found that EGF could directly stimulate IL-8 production, proliferation, and bio-behaviors of lung cancer cells through the activation of EGFR, PI3K, Akt, and Erk signal pathway. EGF-stimulated IL-8 production, phosphorylation of Akt and Erk, and cell proliferation and movement could be inhibited by EGFR inhibitor (Erlotinib), PI3K inhibitor (GDC-0941 BEZ-235 and SHBM1009), and ERK1/2 inhibitor (PD98059). Our data indicate that IL-8 production from lung cancer cells could be initiated by their own produced factors, leading to the recruitment of inflammatory cells in the cancer tissue, and the formation of inflammatory microenvironment. Thus, it seems that the signal pathway of EGFR-PI3K-Akt-Erk can be the potential target of therapies for inflammatory microenvironment in lung cancer.