Acquired resistance mechanisms to afatinib in HER2-amplified gastric cancer cells

Cancer treatment, especially that for breast and lung cancer, has entered a new era and continues to evolve, with the development of genome analysis technology and the advent of molecular targeted drugs including tyrosine kinase inhibitors. Nevertheless, acquired drug resistance to molecular targeted drugs is unavoidable, creating a clinically challenging problem. We recently reported the antitumor effect of a pan-HER inhibitor, afatinib, against human epidermal growth factor receptor 2 (HER2)-amplified gastric cancer cells. The purpose of the present study was to identify the mechanisms of acquired afatinib resistance and to investigate the treatment strategies for HER2-amplified gastric cancer cells. Two afatinib-resistant gastric cancer cell lines were established from 2 HER2-amplified cell lines, N87 and SNU216. Subsequently, we investigated the molecular profiles of resistant cells. The activation of the HER2 pathway was downregulated in N87-derived resistant cells, whereas it was upregulated in SNU216-derived resistant cells. In the N87-derived cell line, both MET and AXL were activated, and combination treatment with afatinib and cabozantinib, a multikinase inhibitor that inhibits MET and AXL, suppressed the cell growth of cells with acquired resistance both in vitro and in vivo. In the SNU216-derived cell line, YES1, which is a member of the Src family, was remarkably activated, and dasatinib, a Src inhibitor, exerted a strong antitumor effect in these cells. In conclusion, we identified MET and AXL activation in addition to YES1 activation as novel mechanisms of afatinib resistance in HER2-driven gastric cancer. Our results also indicated that treatment strategies targeting individual mechanisms of resistance are key to overcoming such resistance

Hybrid Chiral MoS₂ Layers for Spin‐Polarized Charge Transport and Spin‐Dependent Electrocatalytic Applications

【研究成果】電流中の“スピン”の制御により水電解の効率化を実現 --水素エネルギーによる持続可能な社会へ大きく貢献--. 京都大学プレスリリース. 2022-05-06.The chiral-induced spin selectivity effect enables the application of chiral organic materials for spintronics and spin-dependent electrochemical applications. It is demonstrated on various chiral monolayers, in which their conversion efficiency is limited. On the other hand, relatively high spin polarization (SP) is observed on bulk chiral materials; however, their poor electronic conductivities limit their application. Here, the design of chiral MoS₂ with a high SP and high conductivity is reported. Chirality is introduced to the MoS₂ layers through the intercalation of methylbenzylamine molecules. This design approach activates multiple tunneling channels in the chiral layers, which results in an SP as high as 75%. Furthermore, the spin selectivity suppresses the production of H₂O₂ by-product and promotes the formation of ground state O₂ molecules during the oxygen evolution reaction. These potentially improve the catalytic activity of chiral MoS₂. The synergistic effect is demonstrated as an interplay of the high SP and the high catalytic activity of the MoS₂ layer on the performance of the chiral MoS₂ for spin-dependent electrocatalysis. This novel approach employed here paves way for the development of other novel chiral systems for spintronics and spin-dependent electrochemical applications

Pentacoordinated Carboxylate π-Allyl Nickel Complexes as Key Intermediates for the Ni-Catalyzed Direct Amination of Allylic Alcohols

International audienceDirect amination of allylic alcohols with primary and secondary amines catalyzed by a system made of [Ni(1,5-cyclooctadiene)2 ] and 1,1'-bis(diphenylphosphino)ferrocene was effectively enhanced by adding nBu4 NOAc and molecular sieves, affording the corresponding allyl amines in high yield with high monoallylation selectivity for primary amines and high regioselectivity for monosubstituted allylic alcohols. Such remarkable additive effects of nBu4 NOAc were elucidated by isolating and characterizing some nickel complexes, manifesting the key role of a charge neutral pentacoordinated η(3) -allyl acetate complex in the present system, in contrast to usual cationic tetracoordinated complexes earlier reported in allylic substitution reactions

Surgeons’ involvement in COVID-19 treatment: a practice by a regional core hospital in Japan to avoid physician burnout

Abstract Background To prevent task accumulation on certain divisions, our institution developed a unique system of allocating inpatient treatment of COVID-19 patients to doctors who were not specialized in respiratory infections. The objective of this study was to investigate whether surgeons can be involved in the COVID-19 inpatient treatment without negatively affecting patient outcome, and how such involvement can affect the wellbeing of surgeons. Methods There were 300 patients diagnosed with COVID-19 and hospitalized from January to June 2021, and 160 of them were treated by the redeployed doctors. They were divided into 3 groups based on the affiliation of the treating doctor. Patient characteristics and outcomes were compared between the groups. In addition, the impact of COVID-19 duty on participating surgeons was investigated from multiple perspectives, and a postduty survey was conducted. Results There were 43 patients assigned to the Department of Surgery. There were no differences in the backgrounds and outcomes of patients compared with other groups. The surgeon’s overtime hours were significantly longer during the duty period, despite no change in the number of operations and the complication rate. The questionnaire revealed that there was a certain amount of mental and physical burden from the COVID-19 duty. Conclusion Surgeons can take part in inpatient COVID-19 treatment without affecting patient outcome. However, as such duty could negatively affect the surgeons’ physical and mental wellbeing, further effort is needed to maintain the balance of fulfilling individual and institutional needs

Application of amplicon-based targeted sequencing with the molecular barcoding system to detect uncommon minor EGFR mutations in patients with treatment-naïve lung adenocarcinoma

Abstract Background In lung cancer, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor sensitizing mutations co-existing with rare minor EGFR mutations are known as compound mutations. These minor EGFR mutations can lead to acquired resistance after EGFR tyrosine kinase inhibitor treatment, so determining the mutation status of patients is important. However, using amplicon-based targeted deep sequencing based on next-generation sequencing to characterize mutations is prone to sequencing error. We therefore assessed the benefit of incorporating molecular barcoding with high-throughput sequencing to investigate genomic heterogeneity in treatment-naïve patients who have undergone resection of their non-small cell lung cancer (NSCLC) EGFR mutations. Methods We performed amplicon-based targeted sequencing with the molecular barcoding system (MBS) to detect major common EGFR mutations and uncommon minor mutations at a 0.5% allele frequency in fresh–frozen lung cancer samples. Results Profiles of the common mutations of EGFR identified by MBS corresponded with the results of clinical testing in 63 (98.4%) out of 64 cases. Uncommon mutations of EGFR were detected in seven cases (10.9%). Among the three types of major EGFR mutations, patients with the G719X mutation had a significantly higher incidence of compound mutations than those with the L858R mutation or exon 19 deletion (p = 0.0052). This was validated in an independent cohort from the Cancer Genome Atlas dataset (p = 0.018). Conclusions Our findings demonstrate the feasibility of using the MBS to establish an accurate NSCLC patient genotype. This work will help understand the molecular basis of EGFR compound mutations in NSCLC, and could aid the development of new treatment modalities