Altered splicing of ATG16-L1 mediates acquired resistance to tyrosine kinase inhibitors of EGFR by blocking autophagy in non-small cell lung cancer

PPP3CB overexpression mediates EGFR TKI resistance in lung tumors via calcineurin/MEK/ERK signaling

Despite initial high response rates to first-line EGFR TKI, all non-small-cell lung cancer (NSCLC) with EGFR-activating mutation will ultimately develop resistance to treatment. Identification of resistance mechanisms is critical to adapt treatment and improve patient outcomes. Here, we show that a PPP3CB transcript that encodes full-length catalytic subunit 2B of calcineurin accumulates in EGFR-mutant NSCLC cells with acquired resistance against different EGFR TKIs and in post-progression biopsies of NSCLC patients treated with EGFR TKIs. Neutralization of PPP3CB by siRNA or inactivation of calcineurin by cyclosporin A induces apoptosis in resistant cells treated with EGFR TKIs. Mechanistically, EGFR TKIs increase the cytosolic level of calcium and trigger activation of a calcineurin/MEK/ERK pathway that prevents apoptosis. Combining EGFR, calcineurin, and MEK inhibitors overcomes resistance to EGFR TKI in both in vitro and in vivo models. Our results identify PPP3CB overexpression as a new mechanism of acquired resistance to EGFR TKIs, and provide a promising therapeutic approach for NSCLC patients that progress under TKI treatment.

Is Autophagy Targeting a Valid Adjuvant Strategy in Conjunction with Tyrosine Kinase Inhibitors?

Tyrosine kinase inhibitors (TKIs) represent a relatively large class of small-molecule inhibitors that compete with ATP for the catalytic binding site of tyrosine kinase proteins. While TKIs have demonstrated effectiveness in the treatment of multiple malignancies, including chronic myelogenous leukemia, gastrointestinal tumors, non-small cell lung cancers, and HER2-overexpressing breast cancers, as is almost always the case with anti-neoplastic agents, the development of resistance often imposes a limit on drug efficacy. One common survival response utilized by tumor cells to ensure their survival in response to different stressors, including anti-neoplastic drugs, is that of autophagy. The autophagic machinery in response to TKIs in multiple tumor models has largely been shown to be cytoprotective in nature, although there are a number of cases where autophagy has demonstrated a cytotoxic function. In this review, we provide an overview of the literature examining the role that autophagy plays in response to TKIs in different preclinical tumor model systems in an effort to determine whether autophagy suppression or modulation could be an effective adjuvant strategy to increase efficiency and/or overcome resistance to TKIs.

RNA splicing alterations in lung cancer pathogenesis and therapy

RNA splicing alterations are widespread and play critical roles in cancer pathogenesis and therapy. Lung cancer is highly heterogeneous and causes the most cancer-related deaths worldwide. Large-scale multi-omics studies have not only characterized the mutational landscapes but also discovered a plethora of transcriptional and post-transcriptional changes in lung cancer. Such resources have greatly facilitated the development of new diagnostic markers and therapeutic options over the past two decades. Intriguingly, altered RNA splicing has emerged as an important molecular feature and therapeutic target of lung cancer. In this review, we provide a brief overview of splicing dysregulation in lung cancer and summarize the recent progress on key splicing events and splicing factors that contribute to lung cancer pathogenesis. Moreover, we describe the general strategies targeting splicing alterations in lung cancer and highlight the potential of combining splicing modulation with currently approved therapies to combat this deadly disease. This review provides new mechanistic and therapeutic insights into splicing dysregulation in cancer.

Comparing Gefitinib and Traditional Chemotherapy for Better Survival in Patients With Non-Small Cell Lung Cancer: A Systematic Review

Current non-small cell lung cancer (NSCLC) treatment consists of various combinations of surgery, chemotherapy, and/or radiation, depending on the tumor stage. Individuals with stage II-IIIa NSCLC undergo surgery, followed by combination chemotherapy containing cisplatin, such as vinorelbine + cisplatin. Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), such as gefitinib, act by inhibiting any signaling pathway containing the EGFR mutation and inhibiting the growth of NSCLC. TKI is a treatment option in advanced NSCLC, resulting in more prolonged progression-free survival (PFS). This manuscript aims to evaluate the influence of utilizing gefitinib - either alone or in combination with conventional chemotherapeutic drug regimens upon NSCLC patient profile survival parameters. A systematic literature review was conducted across multiple scientific literature repositories. The review was performed using the preferred reporting items for systematic reviews and meta-analyses (PRISMA) 2020. There were six randomized clinical trials (RCT) and five retrospective studies. The overall consensus based on the end outcome of each published journal on the effectiveness of gefitinib as a treatment option for NSCLC indicated that there was a notable difference in overall survival (OS) and progression-free survival (PFS) and disease-free survival (DFS) datasets. Gefitinib use correlated with increased timeframes for multiple patient survival parameters within articles shortlisted in this investigation. However, more comprehensive investigations are required to validate such correlations. Gefitinib did demonstrate the potential to provide beneficial effects and counteract NSCLC within such patients.