Antitumor effect of afatinib, as a human epidermal growth factor receptor 2-targeted therapy, in lung cancers harboring HER2 oncogene alterations

Lung cancer as a paradigm for precision oncology in solid tumours

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death in the western world. However, the combination of molecular genotyping and subsequent systematic treatment of decoded target structures is a prime example of precision oncology in solid tumours. In this review, current targets of approved therapeutics and potential targets in clinical and preclinical trials are outlined. Furthermore, immune checkpoint inhibitors, as promising new therapeutic options, which have already been applied successfully in cases of lung cancer, are introduced. A major issue of targeted treatment of lung tumours is the persistent development of resistance. The underlying mechanisms and established and potentially applicable alternative therapeutic approaches are described. In this process of precision oncology, immunohistochemistry, fluorescence in situ hybridization, and parallel sequencing are crucial diagnostic tools.

Estimation of age-related DNA degradation from formalin-fixed and paraffin-embedded tissue according to the extraction methods

Techniques for the extraction and use of nucleic acids from formalin-fixed and paraffin-embedded (FFPE) tissues, preserved over long time periods in libraries, have been developed. However, DNA extracted from FFPE tissues is generally damaged, and long-term storage may affect DNA quality. Therefore, it is important to elucidate the effect of long-term storage on FFPE tissues and evaluate the techniques used to extract DNA from them. In the present study, the yield, purity, and integrity of DNA in FFPE tissue samples was evaluated. Two DNA extraction techniques were used: A silica-binding DNA collection method using QIAamp DNA FFPE Tissue kit (QIA) and a total tissue DNA collection method using a WaxFree DNA extraction kit (WAX). A total of 25 FFPE tissues from lung adenocarcinomas were studied, which had been surgically resected and fixed at Okayama University Hospital prior to examination and subsequent storage at room temperature for 0.5, 3, 6, 9 and 12 years. Extracted DNA was quantified using ultraviolet absorbance, fluorescent dye, and quantitative polymerase chain reaction (qPCR). The quality of the DNA was defined by the absorbance ratio of 260 to 280 nm (A260/280) and Q-score, which is the quantitative value of qPCR product size ratio. The results demonstrated that the yield of total DNA extracted using WAX was significantly greater than when QIA was used (P<0.01); however, DNA extracted using WAX included more contaminants and was significantly more fragmented compared with DNA extracted using QIA (P<0.01). Aging had no significant effect on absolute DNA yield or DNA purity, although it did significantly contribute to increased DNA degradation for both QIA and WAX extraction (QIA P=0.02, WAX P=0.03; 0.5 years vs. 3 years, QIA P<0.01, WAX P=0.03; 9 years vs. 12 years). Both extraction methods are viable depending on whether high yield or high quality of extracted DNA is required. However, due to the increased degradation with age, storage time limits the available DNA in FFPE tissues regardless of the extraction method.

Epigallocatechin-3-gallate augments the therapeutic effects of benzo[a]pyrene-mediated lung carcinogenesis

Our previous study found curcumin and vitamin E to have protective effects against benzo[a]pyrene (BaP) exposure in human normal lung epithelial BEAS-2B cells. The first objective of this study was to determine whether epigallocatechin-3-gallate (EGCG) elicited the same response. Co-treatment with 5 µM BaP and 20 µM EGCG in BEAS-2B promoted a significant reduction in cell viability and greater G2/M cell cycle arrest, induction of ROS, and reductions in BaP-induced CYP1A1/CYP1B1/COMT, EGFR, p-Akt (Ser473), p-p53 (Thr55), and survivin mRNA/protein expression, as well as an increase in p-p53 (Ser15). Based on these findings, the second objective was to extend the investigation by developing a novel BaP-transformed BEAS-2B cell line, BEAS-2B_BaP , to examine the effects of EGCG when co-administered with gefitinib, an EGFR tyrosine kinase inhibitor. Cell colony formation assay demonstrated in vitro tumorigenic potential of BEAS-2B_BaP , which had an overexpression of EGFR. Viability testing revealed gefitinib co-treatment with EGCG resulted in more cell death compared with gefitinib alone. Co-treated cells had greater reductions in gefitinib-induced CYP1A1/CYB1B1, EGFR, cyclin D1, p-Akt (Ser473), and survivin mRNA/protein expression, as well as an increase in p-p53 (Ser15). Therefore, EGCG was found to promote greater cytotoxicity to BEAS-2B co-treated with BaP and BEAS-2B_BaP upon gefitinib co-treatment through regulating metabolism enzymes and signaling pathways involving EGFR and p53. These findings suggest that EGCG did not act as a protective compound in BEAS-2B after acute BaP exposure, but has the potential to be a useful adjuvant chemotherapeutic compound when coupled with gefitinib for chemosensitization. © 2017 BioFactors, 43(4):529-539, 2017.

Blocking autophagy improves the anti-tumor activity of afatinib in lung adenocarcinoma with activating EGFR mutations in vitro and in vivo

Afatinib, a second-generation tyrosine kinase inhibitor (TKI), has been approved for the treatment of advanced EGFR-mutant non-small cell lung cancer (NSCLC). However, afatinib’s clinical application is still hampered by acquired resistance. Recently, autophagy is considered as an important mechanism of resistance to TKI. Herein, we investigated the autophagy induction as well as its influence on anti-lung adenocarcinoma activity of afatinib in two activating EGFR-mutants H1975 and H1650 cells. First, Growth inhibition and caspase-dependent apoptosis were observed in afatinib-treated H1975 and H1650 cells. Then we confirmed afatinib-induced autophagy in H1975 and H1650 cells. Importantly, autophagy inhibition using chloroquine (CQ) and 3-MA enhanced the cytotoxicity of afatinib, elucidating the cytoprotective role of autophagy in lung adenocarcinoma therapy with afatinib. Further study suggested that Akt/mTOR and Erk signaling pathways were involved in afatinib-induced autophagy, and reactive oxygen species (ROS) acted as an intracellular transducer regulating both autophagy and apoptosis in afatinib-treated H1975 and H1650 cells. Moreover, the in vivo experiment in xenograft model using H1975 cell line confirmed the enhanced anti-lung adenocarcinoma efficacy of afatinib when combined with autophagy inhibitor CQ. Thus, blocking autophagy may be a promising strategy to overcome resistance and increase sensitivity to afatinib in lung adenocarcinoma harboring activating EGFR mutations.

Clinical sequencing using a next-generation sequencing-based multiplex gene assay in patients with advanced solid tumors

Advances in next‐generation sequencing (NGS) technologies have enabled physicians to test for genomic alterations in multiple cancer‐related genes at once in daily clinical practice. In April 2015, we introduced clinical sequencing using an NGS‐based multiplex gene assay (OncoPrime) certified by the Clinical Laboratory Improvement Amendment. This assay covers the entire coding regions of 215 genes and the rearrangement of 17 frequently rearranged genes with clinical relevance in human cancers. The principal indications for the assay were cancers of unknown primary site, rare tumors, and any solid tumors that were refractory to standard chemotherapy. A total of 85 patients underwent testing with multiplex gene assay between April 2015 and July 2016. The most common solid tumor types tested were pancreatic (n = 19; 22.4%), followed by biliary tract (n = 14; 16.5%), and tumors of unknown primary site (n = 13; 15.3%). Samples from 80 patients (94.1%) were successfully sequenced. The median turnaround time was 40 days (range, 18–70 days). Potentially actionable mutations were identified in 69 of 80 patients (86.3%) and were most commonly found in TP53 (46.3%), KRAS (23.8%), APC (18.8%), STK11 (7.5%), and ATR (7.5%). Nine patients (13.0%) received a subsequent therapy based on the NGS assay results. Implementation of clinical sequencing using an NGS‐based multiplex gene assay was feasible in the clinical setting and identified potentially actionable mutations in more than 80% of patients. Current challenges are to incorporate this genomic information into better therapeutic decision making.

Interaction of cytokeratin 19 head domain and HER2 in the cytoplasm leads to activation of HER2-Erk pathway

HER2 is a receptor tyrosine kinase and its upregulation via activating mutations or amplification has been identified in some malignant tumors, including lung cancers. Because HER2 can be a therapeutic target in HER2-driven malignancies, it is important to understand the molecular mechanisms of HER2 activation. In the current study, we identified that cytokeratin 19 (KRT19) binds to HER2 at the inside face of plasma membrane. HER2 and KRT19, which were concurrently introduced to a human embryonic kidney 293 T cells, revealed an association with each other and resulted in phosphorylation of HER2 with the subsequent activation of a downstream Erk-associated pathway. A binding assay revealed that both the NH2-terminal head domain of KRT19 and the COOH-terminal domain of HER2 were essential for their binding. To investigate the impact of the interaction between HER2 and KRT19 in lung cancer, we examined their expressions and localizations in lung cancers. We found that KRT19 was highly expressed in HER2-positive lung cancer cells, and KRT19 and HER2 were co-localized at the cell membrane. In conclusion, we found that KRT19 intracellularly binds to HER2, playing a critical role in HER2 activation.

Interplay between Cellular and Molecular Inflammatory Mediators in Lung Cancer

Inflammation is a component of the tumor microenvironment and represents the 7th hallmark of cancer. Chronic inflammation plays a critical role in tumorigenesis. Tumor infiltrating inflammatory cells mediate processes associated with progression, immune suppression, promotion of neoangiogenesis and lymphangiogenesis, remodeling of extracellular matrix, invasion and metastasis, and, lastly, the inhibition of vaccine-induced antitumor T cell response. Accumulating evidence indicates a critical role of myeloid cells in the pathophysiology of human cancers. In contrast to the well-characterized tumor-associated macrophages (TAMs), the significance of granulocytes in cancer has only recently begun to emerge with the characterization of tumor-associated neutrophils (TANs). Recent studies show the importance of CD47 in the interaction with macrophages inhibiting phagocytosis and promoting the migration of neutrophils, increasing inflammation which can lead to recurrence and progression in lung cancer. Currently, therapies are targeted towards blocking CD47 and enhancing macrophage-mediated phagocytosis. However, antibody-based therapies may have adverse effects that limit its use.

Antitumor effect of afatinib, as a human epidermal growth factor receptor 2-targeted therapy, in lung cancers harboring HER2 oncogene alterations

Human epidermal growth factor receptor 2 (HER2) is a member of the HER family of proteins containing four receptor tyrosine kinases. It plays an important role in the pathogenesis of certain human cancers. In non-small-cell lung cancer (NSCLC), HER2 amplification or mutations have been reported. However, little is known about the benefit of HER2-targeted therapy for NSCLCs harboring HER2 alterations. In this study, we investigated the antitumor effect of afatinib, an irreversible epidermal growth factor receptor (EGFR)-HER2 dual inhibitor, in lung cancers harboring HER2 oncogene alterations, including novel HER2 mutations in the transmembrane domain, which we recently identified. Normal bronchial epithelial cells, BEAS-2B, ectopically overexpressing wild-type HER2 or mutants (A775insYVMA, G776VC, G776LC, P780insGSP, V659E, and G660D) showed constitutive autophosphorylation of HER2 and activation of downstream signaling. They were sensitive to afatinib, but insensitive to gefitinib. Furthermore, we examined the antitumor activity of afatinib and gefitinib in several NSCLC cell lines, and investigated the association between their genetic alterations and sensitivity to afatinib treatment. In HER2-altered NSCLC cells (H2170, Calu-3, and H1781), afatinib downregulated the phosphorylation of HER2 and EGFR as well as their downstream signaling, and induced an antiproliferative effect through G1 arrest and apoptotic cell death. In contrast, HER2- or EGFR-non-dependent NSCLC cells were insensitive to afatinib. In addition, these effects were confirmed in vivo by using a xenograft mouse model of HER2-altered lung cancer cells. Our results suggest that afatinib is a therapeutic option as a HER2-targeted therapy for NSCLC harboring HER2 amplification or mutations.