Antitumor activity of histone deacetylase inhibitor chidamide alone or in combination with epidermal growth factor receptor tyrosine kinase inhibitor icotinib in NSCLC

The cell line models to study tyrosine kinase inhibitors in non-small cell lung cancer with mutations in the epidermal growth factor receptor: A scoping review

Non-Small Cell Lung Cancer (NSCLC) represents ∼85% of all lung cancers and ∼15-20% of them are characterized by mutations affecting the Epidermal Growth Factor Receptor (EGFR). For several years now, a class of tyrosine kinase inhibitors was developed, targeting sensitive mutations affecting the EGFR (EGFR-TKIs). To date, the main burden of the TKIs employment is due to the onset of resistance mutations. This scoping review aims to resume the current situation about the cell line models employed for the in vitro evaluation of resistance mechanisms induced by EGFR-TKIs in oncogene-addicted NSCLC. Adenocarcinoma results the most studied NSCLC histotype with the H1650, H1975, HCC827 and PC9 mutated cell lines, while Gefitinib and Osimertinib the most investigated inhibitors. Overall, data collected frame the current advancement of this topic, showing a plethora of approaches pursued to overcome the TKIs resistance, from RNA-mediated strategies to the innovative combination therapies.

Role and mechanistic actions of protein kinase inhibitors as an effective drug target for cancer and COVID

Kinases can be grouped into 20 families which play a vital role as a regulator of neoplasia, metastasis, and cytokine suppression. Human genome sequencing has discovered more than 500 kinases. Mutations of the kinase itself or the pathway regulated by kinases leads to the progression of diseases such as Alzheimer's, viral infections, and cancers. Cancer chemotherapy has made significant leaps in recent years. The utilization of chemotherapeutic agents for treating cancers has become difficult due to their unpredictable nature and their toxicity toward the host cells. Therefore, targeted therapy as a therapeutic option against cancer-specific cells and toward the signaling pathways is a valuable avenue of research. SARS-CoV-2 is a member of the Betacoronavirus genus that is responsible for causing the COVID pandemic. Kinase family provides a valuable source of biological targets against cancers and for recent COVID infections. Kinases such as tyrosine kinases, Rho kinase, Bruton tyrosine kinase, ABL kinases, and NAK kinases play an important role in the modulation of signaling pathways involved in both cancers and viral infections such as COVID. These kinase inhibitors consist of multiple protein targets such as the viral replication machinery and specific molecules targeting signaling pathways for cancer. Thus, kinase inhibitors can be used for their anti-inflammatory, anti-fibrotic activity along with cytokine suppression in cases of COVID. The main goal of this review is to focus on the pharmacology of kinase inhibitors for cancer and COVID, as well as ideas for future development.

Chidamide, a novel histone deacetylase inhibitor, inhibits laryngeal cancer progression in vitro and in vivo

Although surgery is an important treatment for laryngeal cancer, surgery has a significant negative impact on the quality of life of patients, and many patients have poor tolerance to surgery. Therefore, alternative chemotherapeutic drugs are an important research hotspot. Chidamide is a histone deacetylase inhibitor that selectively inhibits the expression of type I and IIb histone deacetylases (1, 2, 3 and 10). It has a significant anticancer effect on a variety of solid tumours. This study verified the inhibitory effect of chidamide on laryngeal carcinoma. We conducted a variety of cellular and animal experiments to explore how chidamide inhibits the development of laryngeal cancer. The results showed that chidamide had significant antitumour activity against laryngeal carcinoma cells and xenografts and could induce cell apoptosis, ferroptosis and pyroptosis. This study provides a potential option for the treatment of laryngeal cancer.

Histone deacetylases modulate resistance to the therapy in lung cancer

The acetylation status of histones located in both oncogenes and tumor suppressor genes modulate cancer hallmarks. In lung cancer, changes in the acetylation status are associated with increased cell proliferation, tumor growth, migration, invasion, and metastasis. Histone deacetylases (HDACs) are a group of enzymes that take part in the elimination of acetyl groups from histones. Thus, HDACs regulate the acetylation status of histones. Although several therapies are available to treat lung cancer, many of these fail because of the development of tumor resistance. One mechanism of tumor resistance is the aberrant expression of HDACs. Specific anti-cancer therapies modulate HDACs expression, resulting in chromatin remodeling and epigenetic modification of the expression of a variety of genes. Thus, HDACs are promising therapeutic targets to improve the response to anti-cancer treatments. Besides, natural compounds such as phytochemicals have potent antioxidant and chemopreventive activities. Some of these compounds modulate the deregulated activity of HDACs (e.g. curcumin, apigenin, EGCG, resveratrol, and quercetin). These phytochemicals have been shown to inhibit some of the cancer hallmarks through HDAC modulation. The present review discusses the epigenetic mechanisms by which HDACs contribute to carcinogenesis and resistance of lung cancer cells to anticancer therapies.

Therapeutic potential of tucidinostat, a subtype-selective HDAC inhibitor, in cancer treatment

Histone deacetylase (HDAC) is one of the most characterized epigenetic modifiers, modulating chromatin structure and gene expression, which plays an important role in cell cycle, differentiation and apoptosis. Dysregulation of HDAC promotes cancer progression, thus inhibitors targeting HDACs have evidently shown therapeutic efficacy in multiple cancers. Tucidinostat (formerly known as chidamide), a novel subtype-selective HDAC inhibitor, inhibits Class I HDAC1, HDAC2, HDAC3, as well as Class IIb HDAC10. Tucidinostat is approved in relapsed or refractory (R/R) peripheral T-cell lymphoma (PTCL), advanced breast cancer and R/R adult T-cell leukemia-lymphoma (ATLL). Compared with other HDAC inhibitors, tucidinostat shows notable antitumor activity, remarkable synergistic effect with immunotherapy, and manageable toxicity. Here, we comprehensively summarize recent advances in tucidinostat as both monotherapy and a regimen of combination therapy in both hematological and solid malignancies in clinic. Further studies will endeavor to identify more combination strategies with tucidinostat and to identify specific clinical biomarkers to predict the therapeutic effect.

Selinexor improves the anti-cancer effect of tucidinostat on TP53 wild-type breast cancer

Histone deacetylase (HDAC) is closely related to the initiation and development of breast cancer (BC). Its inhibitor (HDACi) has been used to treat BC, while the efficacy of clinical trials was not reached expectations. HDACi combined with other drugs may be an effective strategy. This study explored the effect of HDACi tucidinostat combined with selinexor, an exportin 1 (XPO1) inhibitor, on ER⁺Her2^- BC cell lines of MCF-7 (wt-TP53), MDA-MB-175 (wt-TP53), MDA-MB-134 (mut-TP53) and T47D (mut-TP53) in vitro and cell derived xenografts (CDX) of MCF-7 in nude mice in vivo. Results showed that both tucidinostat and selinexor showed better inhibitory activities on wt-TP53 BC (MCF-7 and MDA-MB-175) comparing with mut-TP53 BC (MDA-MB-134 and T47D). Tucidinostat combined with selinexor significantly improved the effects of tucidinostat alone on the proliferation and invasion inhibitions and apoptosis promotions of MCF-7 and MDA-MB-175 cells in vitro. It also significantly enhanced the effects of tucidinostat on up-regulating the expression levels of acetyl-p53, nuclear p53, total p53, p21, Bax and Cleaved Caspase-3, and down-regulating the expression levels of Cyclin D1 and Bcl-2 in MCF-7 or MDA-MB-175 cells. Results consistent with in vitro were also obtained in CDX of MCF-7 in vivo. Taken together, we believe that tucidinostat and selinexor are potentially effective drug combinations for the treatment of wt-TP53 BC, and the molecular mechanism may be through enhancing the activity of p53 in the nucleus of BC cells to suppress proliferation and invasion and promote apoptosis.

INSIGHT 2: a phase II study of tepotinib plus osimertinib in MET-amplified NSCLC and first-line osimertinib resistance

MET amplification (METamp), a mechanism of acquired resistance to EGFR tyrosine kinase inhibitors, occurs in up to 30% of patients with non-small-cell lung cancer (NSCLC) progressing on first-line osimertinib. Combining osimertinib with a MET inhibitor, such as tepotinib, an oral, highly selective, potent MET tyrosine kinase inhibitor, may overcome METamp-driven resistance. INSIGHT 2 (NCT03940703), an international, open-label, multicenter phase II trial, assesses tepotinib plus osimertinib in patients with advanced/metastatic EGFR-mutant NSCLC and acquired resistance to first-line osimertinib and METamp, determined centrally by fluorescence in situ hybridization (gene copy number ≥5 and/or MET/CEP7 ≥2) at time of progression. Patients will receive tepotinib 500 mg (450 mg active moiety) plus osimertinib 80 mg once-a-day. The primary end point is objective response, and secondary end points include duration of response, progression-free survival, overall survival and safety. Trial registration number: NCT03940703 (clinicaltrials.gov).

Preclinical Evaluation of the HDAC Inhibitor Chidamide in Transformed Follicular Lymphoma

The key factors leading to transformed follicular lymphoma (t-FL) include the aberrations of epigenetic modifiers as early and driving events, especially mutations in the gene encoding for histone acetyltransferase. Therefore, reversal of this phenomenon by histone deacetylase (HDAC) inhibitors is essential for the development of new treatment strategies in t-FL. Several t-FL cell lines were treated with various doses of chidamide and subjected to cell proliferation, apoptosis and cell cycle analyses with CCK-8 assay, Annexin V/PI assay and flow cytometry, respectively. Chidamide dose-dependently inhibited cell proliferation, caused G0/G1 cycle arrest and triggered apoptosis in t-FL cells. In addition, the effects of chidamide on tumor growth were evaluated in vivo in xenograft models. RNA-seq analysis revealed gene expression alterations involving the PI3K-AKT signaling pathway might account for the mechanism underlying the antitumor activity of chidamide as a single agent in t-FL. These findings provide a basis for further clinical exploration of chidamide as a promising treatment for FL.

[Research Progress of Epigenetic Mechanism in Acquired Resistance of Targeted Therapy in Non-small Cell Lung Cancer]

Patients with oncogenic driver alterations of non-small cell lung cancer (NSCLC) can benefit from targeted therapy, but acquired resistance is inevitable ultimately. Epigenetic modifications, including DNA methylation, histone modifications, non-coding RNA-mediated regulate and chromatin remodeling, are important mechanisms of acquired resistance in targeted therapy of NSCLC. In recent years, studies have found that epigenetic modifications can effectively reverse drug resistance. Targeted therapy combined with epigenetic modifications may become a promising therapeutic strategy. Here, we review the progress of epigenetic mechanism in acquired resistance of targeted therapy in NSCLC, hoping to provide ideas for screening dominant population and overcoming resistance.
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SIRT1/PGC-1α/PPAR-γ Correlate With Hypoxia-Induced Chemoresistance in Non-Small Cell Lung Cancer

Resistance is the major cause of treatment failure and disease progression in non-small cell lung cancer (NSCLC). There is evidence that hypoxia is a key microenvironmental stress associated with resistance to cisplatin, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs), and immunotherapy in solid NSCLCs. Numerous studies have contributed to delineating the mechanisms underlying drug resistance in NSCLC; nevertheless, the mechanisms involved in the resistance associated with hypoxia-induced molecular metabolic adaptations in the microenvironment of NSCLC remain unclear. Studies have highlighted the importance of posttranslational regulation of molecular mediators in the control of mitochondrial function in response to hypoxia-induced metabolic adaptations. Hypoxia can upregulate the expression of sirtuin 1 (SIRT1) in a hypoxia-inducible factor (HIF)-dependent manner. SIRT1 is a stress-dependent metabolic sensor that can deacetylate some key transcriptional factors in both metabolism dependent and independent metabolic pathways such as HIF-1α, peroxisome proliferator-activated receptor gamma (PPAR-γ), and PPAR-gamma coactivator 1-alpha (PGC-1α) to affect mitochondrial function and biogenesis, which has a role in hypoxia-induced chemoresistance in NSCLC. Moreover, SIRT1 and HIF-1α can regulate both innate and adaptive immune responses through metabolism-dependent and -independent ways. The objective of this review is to delineate a possible SIRT1/PGC-1α/PPAR-γ signaling-related molecular metabolic mechanism underlying hypoxia-induced chemotherapy resistance in the NSCLC microenvironment. Targeting hypoxia-related metabolic adaptation may be an attractive therapeutic strategy for overcoming chemoresistance in NSCLC.

Druggable genome and precision medicine in cancer: current challenges

The past decades have seen tremendous developments with respect to "specific" therapeutics that target key signaling molecules to conquer cancer. The key advancements with multiomics technologies, especially genomics, have allowed physicians and molecular oncologists to design "tailor-made" solutions to the specific oncogenes that are deregulated in individual patients, a strategy which has turned out to be successful though the patients quickly develop resistance. The swift integration of multidisciplinary approaches has led to the development of "next generation" therapeutics and, with synergistic therapeutic regimes combined with immune checkpoint inhibitors to reactivate the dampened immune response, has provided the much-needed promise for cancer patients. Despite these advances, a large portion of the druggable genome remains understudied, and the role of druggable genome in the immune system needs further attention. Establishment of patient-derived organoid models has fastened the preclinical validation of novel therapeutics for swift clinical translation. We summarized the current advances and challenges and also stress the importance of biobanking and collection of longitudinal data sets with structured clinical information, as well as the critical role these "high content data sets" will play in designing new therapeutic regimes in a tailor-made fashion.

Anticancer Therapy with HDAC Inhibitors: Mechanism-Based Combination Strategies and Future Perspectives

The increasing knowledge of molecular drivers of tumorigenesis has fueled targeted cancer therapies based on specific inhibitors. Beyond "classic" oncogene inhibitors, epigenetic therapy is an emerging field. Epigenetic alterations can occur at any time during cancer progression, altering the structure of the chromatin, the accessibility for transcription factors and thus the transcription of genes. They rely on post-translational histone modifications, particularly the acetylation of histone lysine residues, and are determined by the inverse action of histone acetyltransferases (HATs) and histone deacetylases (HDACs). Importantly, HDACs are often aberrantly overexpressed, predominantly leading to the transcriptional repression of tumor suppressor genes. Thus, histone deacetylase inhibitors (HDACis) are powerful drugs, with some already approved for certain hematological cancers. Albeit HDACis show activity in solid tumors as well, further refinement and the development of novel drugs are needed. This review describes the capability of HDACis to influence various pathways and, based on this knowledge, gives a comprehensive overview of various preclinical and clinical studies on solid tumors. A particular focus is placed on strategies for achieving higher efficacy by combination therapies, including phosphoinositide 3-kinase (PI3K)-EGFR inhibitors and hormone- or immunotherapy. This also includes new bifunctional inhibitors as well as novel approaches for HDAC degradation via PROteolysis-TArgeting Chimeras (PROTACs).

Chidamide Inhibits Acute Myeloid Leukemia Cell Proliferation by lncRNA VPS9D1-AS1 Downregulation via MEK/ERK Signaling Pathway

Irregular histone modification and aberrant lncRNAs expression are closely related to the occurrence of tumors including acute myeloid leukemia (AML). However, the effects and specific underlying molecular mechanism of histone deacetylase inhibitors on lncRNA expression in AML cells are unclear. Here, we reported the effects of a novel histone deacetylase inhibitor Chidamide on proliferation and lncRNA expression in AML cells. Chidamide inhibited cell proliferation, blocked G1/S phase transition, and induced cell apoptosis through the caspase-dependent apoptotic pathway in AML cells. Chidamide also inhibited the formation of subcutaneous tumors. Transcriptome sequencing results showed that 1,195 lncRNAs were co-upregulated and 780 lncRNAs were co-downregulated after Chidamide treatment of SKM-1 cells and THP-1 cells. Combined with transcriptome sequencing data and the gene expression profiling interactive analysis dataset, we found that VPS9D1-AS1 expression was negatively correlated with the survival of AML patients. VPS9D1-AS1 knockdown inhibited cell proliferation, arrested cell cycle, as well as inhibited the formation of subcutaneous tumors in vivo. VPS9D1-AS1 overexpression had the reverse effect. Furthermore, VPS9D1-AS1 knockdown inhibited the MEK/ERK signaling pathway, and thus enhanced the inhibitory effect of Chidamide on AML cell proliferation. These findings suggested that targeted regulation of VPS9D1-AS1 might overcome the limitations of Chidamide in the treatment of AML.

Chidamide increases the sensitivity of Non-small Cell Lung Cancer to Crizotinib by decreasing c-MET mRNA methylation

Introduction: Crizotinib is a kinase inhibitor targeting c-MET/ALK/ROS1 used as the first-line chemical for the treatment of non-small cell lung cancer (NSCLC) with ALK mutations. Although c-MET is frequently overexpressed in 35-72% of NSCLC, most NSCLCs are primarily resistant to crizotinib treatment.

Method: A set of NSCLC cell lines were used to test the effect of chidamide on the primary crizotinib resistance in vitro and in vivo. Relationships between the synergistic effect of chidamide and c-MET expression and RNA methylation were systemically studied with a battery of molecular biological assays.

Results: We found for the first time that chidamide could sensitize the effect of crizotinib in a set of ALK mutation-free NSCLC cell lines, especially those with high levels of c-MET expression. Notably, chidamide could not increase the sensitivity of NSCLC cells to crizotinib cultured in serum-free medium without hepatocyte growth factor (HGF; a c-MET ligand). In contrast, the addition of HGF into the serum-/HGF-free medium could restore the synergistic effect of chidamide. Moreover, the synergistic effect of chidamide could also be abolished either by treatment with c-MET antibody or siRNA-knockdown of c-MET expression. While cells with low or no c-MET expression were primarily resistant to chidamide-crizotinib cotreatment, enforced c-MET overexpression could increase the sensitivity of these cells to chidamide-crizotinib cotreatment. Furthermore, chidamide could decrease c-MET expression by inhibiting mRNA N6-methyladenosine (m6A) modification through the downregulation of METTL3 and WTAP expression. Chidamide-crizotinib cotreatment significantly suppressed the activity of c-MET downstream molecules.

Conclusion: Chidamide downregulated c-MET expression by decreasing its mRNA m6A methylation, subsequently increasing the crizotinib sensitivity of NSCLC cells in a c-MET-/HGF-dependent manner.

The Synergistic Antitumor Activity of Chidamide in Combination with Bortezomib on Gastric Cancer

Purpose

The aim of this study was to investigate the antitumor effect of chidamide in combination with bortezomib on gastric cancer cell lines.

Materials and Methods

First, the sensitivity and IC₅₀ values of chidamide and bortezomib in several gastric cancer cell lines (MGC-803, BGC-823, SGC-7901, and MKN45) were measured using the CCK-8 assay. Then, the relatively insensitive gastric cancer cell lines (MGC-803 and BGC-823) were treated with low concentrations of chidamide alone, bortezomib alone, or chidamide and bortezomib combination to detect the effects on cell proliferation, apoptosis, migration, and invasion. Finally, the inhibitory effect of the combined chidamide and bortezomib treatment on MGC-803 cells was verified in vivo through tumor formation experiments in nude mice.

Results

Compared with low-dose chidamide or bortezomib alone, the low-dose drug combination significantly inhibited the proliferation, migration, and invasion of MGC-803 and BGC-823 cells and induced apoptosis of the cells. The effects of the low-dose chidamide and bortezomib combination reduced the growth on gastric cancer in vivo were investigated by using a subcutaneous tumor mouse model.

Conclusion

Our results suggest that the combination of chidamide and bortezomib can significantly reduce the proliferation, invasion, and migration of MGC-803 and BGC-823 cells, providing a framework for the clinical evaluation of combined therapies for gastric cancers.

Tyrosine Kinase Inhibitors in Cancer: Breakthrough and Challenges of Targeted Therapy

Receptor tyrosine kinases (RTKs) are key regulatory signaling proteins governing cancer cell growth and metastasis. During the last two decades, several molecules targeting RTKs were used in oncology as a first or second line therapy in different types of cancer. However, their effectiveness is limited by the appearance of resistance or adverse effects. In this review, we summarize the main features of RTKs and their inhibitors (RTKIs), their current use in oncology, and mechanisms of resistance. We also describe the technological advances of artificial intelligence, chemoproteomics, and microfluidics in elaborating powerful strategies that could be used in providing more efficient and selective small molecules inhibitors of RTKs. Finally, we discuss the interest of therapeutic combination of different RTKIs or with other molecules for personalized treatments, and the challenge for effective combination with less toxic and off-target effects.

Novel HDAC inhibitor Chidamide synergizes with Rituximab to inhibit diffuse large B-cell lymphoma tumour growth by upregulating CD20

Loss of CD20 is a major obstacle for the retreatment of relapsed/refractory diffuse large B cell lymphoma (DLBCL) with Rituximab-associated regimens. Histone deacetylation causes gene silencing and inhibits CD20 expression. Chidamide is a novel inhibitor for histone deacetylases (HDACs). We hypothesize that Chidamide could overcome Rituximab-mediated down-regulation of CD20 and facilitate Rituximab-induced killing. In this study, we determine the mechanism of synergy of Chidamide with Rituximab in DLBCL using in vitro and in vivo models. We found that the levels of CD20 protein surface expression on five DLBCL cell lines were significantly and positively correlated with the sensitivities of cells to Rituximab. Treatment with Rituximab significantly reduced CD20 surface expression at the protein levels. RNA sequencing showed that Chidamide significantly increased expression of more than 2000 transcriptomes in DLBCL cells, around 1000 transcriptomes belong to the cell membrane and cell periphery pathways, including MS4A1. Chidamide significantly increased CD20 surface expression in DLBCL cell lines. Combination with Chidamide significantly synergized Rituximab-induced cell death in vitro and significantly inhibited tumour growth in DLBCL-bearing xenograft mice. A patient with relapsed/refractory DLBCL achieved a complete response after three cycles combined treatment with Chidamide and Rituximab. In conclusion, our data demonstrate for the first time that inhibition of HDACs by Chidamide significantly enhanced Rituximab-induced tumour growth inhibition in vitro and in vivo. We propose that CD20 surface expression should be used clinically to evaluate treatment response in patients with DLBCL. Chidamide is a promising sensitizer for the retreatment of DLBCL with Rituximab.