Drug combination approach to overcome resistance to EGFR tyrosine kinase inhibitors in lung cancer

Tanshinone IIA reverses gefitinib resistance in EGFR-mutant lung cancer via inhibition of SREBP1-mediated lipogenesis

BACKGROUND AND AIM

Gefitinib resistance is an urgent problem to be solved in the treatment of non-small cell lung cancer (NSCLC). Tanshinone IIA (Tan IIA) is one of the main active components of Salvia miltiorrhiza, which exhibits significant antitumor effects. The aim of this study is to explore the reversal effect of Tan IIA on gefitinib resistance in the epidermal growth factor receptor (EGFR)-mutant NSCLC and the underlying mechanism.

EXPERIMENTAL PROCEDURE

CCK-8, colony formation assay, and flow cytometry were applied to detect the cytotoxicity, proliferation, and apoptosis, respectively. The changes in lipid profiles were measured by electrospray ionization-mass spectrometry (MS)/MS. Western blot, real-time q-PCR, and immunohistochemical were used to detect the protein and the corresponding mRNA levels. The in vivo antitumor effect was validated by the xenograft mouse model.

KEY RESULTS

Co-treatment of Tan IIA enhanced the sensitivity of resistant NSCLC cells to gefitinib. Mechanistically, Tan IIA could downregulate the expression of sterol regulatory element binding protein 1 (SREBP1) and its downstream target genes, causing changes in lipid profiles, thereby reversing the gefitinib-resistance in EGFR-mutant NSCLC cells in vitro and in vivo.

CONCLUSIONS AND IMPLICATIONS

Tan IIA improved gefitinib sensitivity via SREBP1-mediated lipogenesis. Tan IIA could be a potential candidate to enhance sensitivity for gefitinib-resistant NSCLC patients.

Interpreting drug synergy in breast cancer with deep learning using target-protein inhibition profiles

BACKGROUND

Breast cancer is the most common malignancy among women worldwide. Despite advances in treating breast cancer over the past decades, drug resistance and adverse effects remain challenging. Recent therapeutic progress has shifted toward using drug combinations for better treatment efficiency. However, with a growing number of potential small-molecule cancer inhibitors, in silico strategies to predict pharmacological synergy before experimental trials are required to compensate for time and cost restrictions. Many deep learning models have been previously proposed to predict the synergistic effects of drug combinations with high performance. However, these models heavily relied on a large number of drug chemical structural fingerprints as their main features, which made model interpretation a challenge.

RESULTS

This study developed a deep neural network model that predicts synergy between small-molecule pairs based on their inhibitory activities against 13 selected key proteins. The synergy prediction model achieved a Pearson correlation coefficient between model predictions and experimental data of 0.63 across five breast cancer cell lines. BT-549 and MCF-7 achieved the highest correlation of 0.67 when considering individual cell lines. Despite achieving a moderate correlation compared to previous deep learning models, our model offers a distinctive advantage in terms of interpretability. Using the inhibitory activities against key protein targets as the main features allowed a straightforward interpretation of the model since the individual features had direct biological meaning. By tracing the synergistic interactions of compounds through their target proteins, we gained insights into the patterns our model recognized as indicative of synergistic effects.

CONCLUSIONS

The framework employed in the present study lays the groundwork for future advancements, especially in model interpretation. By combining deep learning techniques and target-specific models, this study shed light on potential patterns of target-protein inhibition profiles that could be exploited in breast cancer treatment.

Post-Operational Photodynamic Therapy of the Tumor Bed: Comparative Analysis for Cold Knife and Laser Scalpel Resection

In this paper, we report on a study regarding the efficiency of the post-operational phototherapy of the tumor bed after resection with both a cold knife and a laser scalpel in laboratory mice with CT-26 tumors. Post-operational processing included photodynamic therapy (PDT) with a topically applied chlorin-based photosensitizer (PS), performed at wavelengths of 405 or 660 nm, with a total dose of 150 J/cm2. The selected design of the tumor model yielded zero recurrence in the laser scalpel group and 92% recurrence in the cold knife group without post-processing, confirming the efficiency of the laser scalpel in oncology against the cold knife. The application of PDT after the cold knife resection decreased the recurrence rate to 70% and 42% for the 405 nm and 660 nm procedures, respectively. On the other hand, the application of PDT after the laser scalpel resection induced recurrence rates of 18% and 30%, respectively, for the considered PDT performance wavelengths. The control of the penetration of PS into the tumor bed by fluorescence confocal microscopy indicated the deeper penetration of PS in the case of the cold knife, which presumably provided deeper PDT action, while the low-dose light exposure of deeper tissues without PS, presumably, stimulated tumor recurrence, which was also confirmed by the differences in the recurrence rate in the 405 and 660 nm groups. Irradiation-only light exposures, in all cases, demonstrated higher recurrence rates compared to the corresponding PDT cases. Thus, the PDT processing of the tumor bed after resection could only be recommended for the cold knife treatment and not for the laser scalpel resection, where it could induce tumor recurrence.

Synergetic impact of combined navoximod with cisplatin mitigates chemo-immune resistance via blockading IDO1+ CAFs-secreted Kyn/AhR/IL-6 and pol ζ-prevented CIN in human oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most prevalent aggressive form of HNSC and treated with platinum-based chemotherapy as initial therapy. However, the development of acquired resistance and neurotoxicity to platinum agents poses a significant challenge to treat locally advanced OSCC. Notably, IDO1+ CAFs could promote immunosuppressive TME for OSCC progression. Therefore, we developed a potent IDO1 inhibitor navoximod to overcome chemo-immune resistance via an antitumor immune effect synergized with cisplatin in SCC-9 co-cultured IDO1+/IDO1- CAFs and SCC-7/IDO1+ CAFs-inoculated mice. The in vitro biological assays on IDO1+ CAFs co-cultured OSCC cancer cells supported that combined navoximod with cisplatin could mitigate chemo-immune resistance through blockading IDO1+ CAFs-secreted kynurenine (Kyn)-aryl hydrocarbon receptor (AhR)-IL-6 via suppressing p-STAT3/NF-κB signals and ceasing AhR-induced loss of pol ζ-caused chromosomal instability (CIN). Moreover, the combination elicited antitumor immunity via reducing IDO1+ CAFs-secreted Kyn/AhR and conferring pol ζ in SCC-7/IDO1+ CAFs-inoculated BALB/c mice. Meanwhile, the combination could block cisplatin-induced neurotoxicity and not interfere with chemotherapy. Taken together, the study investigated the promising therapeutic potential of combined navoximod with cisplatin to mitigate tumoral immune resistance via alleviating IDO1+ CAFs-secreted immune-suppression and CIN-caused cisplatin resistance, providing a paradigm for combined chemo-immunotherapy to prolong survival in patients with OSCC.

Sijunzi Tang improves gefitinib resistance by regulating glutamine metabolism

Lung cancer is a major health concern and significant barrier to human well-being and social development. Although targeted therapy has shown remarkable progress in the treatment of lung cancer, the emergence of drug resistance has limited its clinical efficacy. Sijunzi Tang (SJZ) is a classical Chinese herbal formula known for tonifying qi and nourishing the lungs, has been recognized for its potential in lung cancer management. However, the underlying mechanism of its combined use with anti-cancer drugs remains unclear. Here, we investigated the anti-lung cancer efficacy and underlying mechanisms of the combination of gefitinib and SJZ in gefitinib-resistant human lung adenocarcinoma cells (PC-9/GR). We conducted in vitro and in vivo experiments using histopathology and targeted metabolomics approaches. Our results demonstrated that the combination of SJZ and gefitinib exhibited synergistic effects on tumor growth inhibition in PC-9/GR-bearing nude mice. Notably, the co-administration of SJZ and gefitinib synergistically promoted tumor cell apoptosis, potentially through the regulation of BAX and BCL-2 expression. Immunohistochemistry and western blot analysis found down-regulation of GLS, GS, and SLC1A5 expression in the co-administration group compared to the control and the individual treatment groups. Targeted metabolomics revealed significant alterations in the plasma glutamine metabolic markers glutamine, alanine, succinate, glutamate, and pyruvate. Of the glutamine metabolism markers measured in tumor tissues, glutamine and pyruvate demonstrated significant differences across the treatment groups. These findings suggest that administration of SJZ improves gefitinib resistance in the treatment of lung cancer without toxic effects. Moreover, SJZ may affect glutamine metabolism by regulating key targets involved in glutamine metabolism (SLC1A5, GLS, and GS) and modulating the levels of related metabolic markers, ultimately reducing gefitinib resistance.

EGFR TKI resistance in lung cancer cells using RNA sequencing and analytical bioinformatics tools

Epidermal Growth Factor Receptor (EGFR) signaling and EGFR mutations play key roles in cancer pathogenesis, particularly in the development of drug resistance. For the ∼20% of all non-small cell lung cancer (NSCLC) patients that harbor an activating mutation, EGFR tyrosine kinase inhibitors (TKIs) provide initial clinical responses. However, long-term efficacy is not possible due to acquired drug resistance. Despite a gradually increasing knowledge of the mechanisms underpinning the development of resistance in tumors, there has been very little success in overcoming it and it is probable that many additional mechanisms are still unknown. Herein, publicly available RNASeq (RNA sequencing) datasets comparing lung cancer cell lines treated with EGFR TKIs until resistance developed with their corresponding parental cells and protein array data from our own EGFR TKI treated xenograft tumors, were analyzed for differential gene expression, with the intent to investigate the potential mechanisms of drug resistance to EGFR TKIs. Pathway analysis, as well as structural disorder analysis of proteins in these pathways, revealed several key proteins, including DUSP1, DUSP6, GAB2, and FOS, that could be targeted using novel combination therapies to overcome EGFR TKI resistance in lung cancer.

Ginsenosides: a potential natural medicine to protect the lungs from lung cancer and inflammatory lung disease

Lung cancer is the malignancy with the highest morbidity and mortality. Additionally, pulmonary inflammatory diseases, such as pneumonia, acute lung injury, chronic obstructive pulmonary disease (COPD), and pulmonary fibrosis (PF), also have high mortality rates and can promote the development and progression of lung cancer. Unfortunately, available treatments for them are limited, so it is critical to search for effective drugs and treatment strategies to protect the lungs. Ginsenosides, the main active components of ginseng, have been shown to have anti-cancer and anti-inflammatory activities. In this paper, we focus on the beneficial effects of ginsenosides on lung diseases and their molecular mechanisms. Firstly, the molecular mechanism of ginsenosides against lung cancer was summarized in detail, mainly from the points of view of proliferation, apoptosis, autophagy, angiogenesis, metastasis, drug resistance and immunity. In in vivo and in vitro lung cancer models, ginsenosides Rg3, Rh2 and CK were reported to have strong anti-lung cancer effects. Then, in the models of pneumonia and acute lung injury, the protective effect of Rb1 was particularly remarkable, followed by Rg3 and Rg1, and its molecular mechanism was mainly associated with targeting NF-κB, Nrf2, MAPK and PI3K/Akt pathways to alleviate inflammation, oxidative stress and apoptosis. Additionally, ginsenosides may also have a potential health-promoting effect in the improvement of COPD, asthma and PF. Furthermore, to overcome the low bioavailability of CK and Rh2, the development of nanoparticles, micelles, liposomes and other nanomedicine delivery systems can significantly improve the efficacy of targeted lung cancer treatment. To conclude, ginsenosides can be used as both anti-lung cancer and lung protective agents or adjuvants and have great potential for future clinical applications.

Circumvention of Gefitinib Resistance by Repurposing Flunarizine via Histone Deacetylase Inhibition

Gefitinib is an epidermal growth factor receptor tyrosine kinase inhibitor (EGFR TKI) for treating advanced non-small cell lung cancer (NSCLC). However, drug resistance seriously impedes the clinical efficacy of gefitinib. This study investigated the repositioning of the non-oncology drug capable of inhibiting histone deacetylases (HDACs) to overcome gefitinib resistance. A few drug candidates were identified using the in silico repurposing tool "DRUGSURV" and tested for HDAC inhibition. Flunarizine, originally indicated for migraine prophylaxis and vertigo treatment, was selected for detailed investigation in NSCLC cell lines harboring a range of different gefitinib resistance mechanisms (EGFR T790M, KRAS G12S, MET amplification, or PTEN loss). The circumvention of gefitinib resistance by flunarizine was further demonstrated in an EGFR TKI (erlotinib)-refractory patient-derived tumor xenograft (PDX) model in vivo. The acetylation level of cellular histone protein was increased by flunarizine in a concentration- and time-dependent manner. Among the NSCLC cell lines evaluated, the extent of gefitinib resistance circumvention by flunarizine was found to be the most pronounced in EGFR T790M-bearing H1975 cells. The gefitinib-flunarizine combination was shown to induce the apoptotic protein Bim but reduce the antiapoptotic protein Bcl-2, which apparently circumvented gefitinib resistance. The induction of Bim by flunarizine was accompanied by an increase in the histone acetylation and E2F1 interaction with the BIM gene promoter. Flunarizine was also found to upregulate E-cadherin but downregulate the vimentin expression, which subsequently inhibited cancer cell migration and invasion. Importantly, flunarizine was also shown to significantly potentiate the tumor growth suppressive effect of gefitinib in EGFR TKI-refractory PDX in vivo. The findings advocate for the translational application of flunarizine to circumvent gefitinib resistance in the clinic.

Repurposing of triamterene as a histone deacetylase inhibitor to overcome cisplatin resistance in lung cancer treatment

PURPOSE

Cisplatin is the core chemotherapeutic drug used for first-line treatment of advanced non-small cell lung cancer (NSCLC). However, drug resistance is severely hindering its clinical efficacy. This study investigated the circumvention of cisplatin resistance by repurposing non-oncology drugs with putative histone deacetylase (HDAC) inhibitory effect.

METHODS

A few clinically approved drugs were identified by a computational drug repurposing tool called "DRUGSURV" and evaluated for HDAC inhibition. Triamterene, originally indicated as a diuretic, was chosen for further investigation in pairs of parental and cisplatin-resistant NSCLC cell lines. Sulforhodamine B assay was used to evaluate cell proliferation. Western blot analysis was performed to examine histone acetylation. Flow cytometry was used to examine apoptosis and cell cycle effects. Chromatin immunoprecipitation was conducted to investigate the interaction of transcription factors to the promoter of genes regulating cisplatin uptake and cell cycle progression. The circumvention of cisplatin resistance by triamterene was further verified in a patient-derived tumor xenograft (PDX) from a cisplatin-refractory NSCLC patient.

RESULTS

Triamterene was found to inhibit HDACs. It was shown to enhance cellular cisplatin accumulation and potentiate cisplatin-induced cell cycle arrest, DNA damage, and apoptosis. Mechanistically, triamterene was found to induce histone acetylation in chromatin, thereby reducing the association of HDAC1 but promoting the interaction of Sp1 with the gene promoter of hCTR1 and p21. Triamterene was further shown to potentiate the anti-cancer effect of cisplatin in cisplatin-resistant PDX in vivo.

CONCLUSION

The findings advocate further clinical evaluation of the repurposing use of triamterene to overcome cisplatin resistance.

The next generation of EGFR inhibitors: a patenting perspective of PROTACs based EGFR degraders

INTRODUCTION

Abnormal expression of epidermal growth factor receptor (EGFR) contributes to tumor development, especially in non-small cell lung cancer (NSCLC). Although multiple inhibitors have been developed to target diverse EGFR mutations and several have been approved, the inevitable drug resistance and side effect remain a challenge, which motivates novel strategies. Proteolysis-targeting chimeras (PROTACs) have been gaining momentum for their potential as novel therapeutics for human diseases by triggering protein degradation. To date, various potent and specific EGFR PROTACs have been discovered and some of them have entered clinical trials.

AREAS COVERED

This review provides an overview of EGFR degraders in patents from 2016 to 2022. It provides an update of the discovery strategies, chemical structures, and molecular profiling of all available EGFR PROTACs. SciFinder, PubMed, Web of Science, EPO, and CNIPA databases were used for searching the literature and patents for EGFR PROTACs.

EXPERT OPINION

By employing the PROTAC technology, highly potent and selective EGFR degraders based on four generation EGFR inhibitors have been developed, which offer a new strategy to target EGFR mutations and overcome the drug resistance. Despite the satisfactory result in vitro and in vivo studies, their therapeutic value awaits more rigorous preclinical testing and clinical investigation.

A novel EGFR inhibitor acts as potent tool for hypoxia-activated prodrug systems and exerts strong synergistic activity with VEGFR inhibition in vitro and in vivo

Small-molecule EGFR inhibitors have distinctly improved the overall survival especially in EGFR-mutated lung cancer. However, their use is often limited by severe adverse effects and rapid resistance development. To overcome these limitations, a hypoxia-activatable Co(III)-based prodrug (KP2334) was recently synthesized releasing the new EGFR inhibitor KP2187 in a highly tumor-specific manner only in hypoxic areas of the tumor. However, the chemical modifications in KP2187 necessary for cobalt chelation could potentially interfere with its EGFR-binding ability. Consequently, in this study, the biological activity and EGFR inhibition potential of KP2187 was compared to clinically approved EGFR inhibitors. In general, the activity as well as EGFR binding (shown in docking studies) was very similar to erlotinib and gefitinib (while other EGFR-inhibitory drugs behaved different) indicating no interference of the chelating moiety with the EGFR binding. Moreover, KP2187 significantly inhibited cancer cell proliferation as well as EGFR pathway activation in vitro and in vivo. Finally, KP2187 proved to be highly synergistic with VEGFR inhibitors such as sunitinib. This indicates that KP2187-releasing hypoxia-activated prodrug systems are promising candidates to overcome the clinically observed enhanced toxicity of EGFR-VEGFR inhibitor combination therapies.

Recent Advances in Boosting EGFR Tyrosine Kinase Inhibitors-Based Cancer Therapy

Epidermal growth factor receptor (EGFR) plays a key role in signal transduction pathways associated with cell proliferation, growth, and survival. Its overexpression and aberrant activation in malignancy correlate with poor prognosis and short survival. Targeting inhibition of EGFR by small-molecular tyrosine kinase inhibitors (TKIs) is emerging as an important treatment model besides of chemotherapy, greatly reshaping the landscape of cancer therapy. However, they are still challenged by the off-targeted toxicity, relatively limited cancer types, and drug resistance after long-term therapy. In this review, we summarize the recent progress of oral, pulmonary, and injectable drug delivery systems for enhanced and targeting TKI delivery to tumors and reduced side effects. Importantly, EGFR-TKI-based combination therapies not only greatly broaden the applicable cancer types of EGFR-TKI but also significantly improve the anticancer effect. The mechanisms of TKI resistance are summarized, and current strategies to overcome TKI resistance as well as the application of TKI in reversing chemotherapy resistance are discussed. Finally, we provide a perspective on the future research of EGFR-TKI-based cancer therapy.

A Mechanism Exploration for the Yi-Fei-San-Jie Formula against Non-Small-Cell Lung Cancer Based on UPLC-MS/MS, Network Pharmacology, and In Silico Verification

Non-small-cell lung cancer (NSCLC) is one of the most prevalent cancers worldwide. A Yi-Fei-San-Jie formula (YFSJF), widely used in NSCLC treatment in south China, has been validated in clinical studies. However, the pharmacological mechanism behind it remains unclear. In this study, 73 compounds were identified using ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), with 58 enrolled in network pharmacology. The protein-protein interaction network, functional enrichment analysis, and compound-target-pathway network were constructed using 74 overlapping targets from 58 drugs and NSCLC. YFSJF has many targets and pathways in the fight against NSCLC. PIK3R1, PIK3CA, and AKT1 were identified as key targets, and the PI3K/AKT pathway was identified as the key pathway. According to the Human Protein Atlas (THPA) database and the Kaplan-Meier Online website, the three key targets had varying expression levels in normal and abnormal tissues and were linked to prognosis. Molecular docking and dynamics simulations verified that hub compounds have a strong affinity with three critical targets. This study revealed multiple compounds, targets, and pathways for YFSJF against NSCLC and suggested that YFSJF might inhibit PIK3R1, PIK3CA, and AKT1 to suppress the PI3K/AKT pathway and play its pharmacological role.

Second generation Spautin-1 analogues targeting EGFR-mutant non-small cell lung cancer cells

Treatment of advanced stage epidermal growth factor receptor (EGFR)-mutant non-small cell lung cancer (NSCLC) is often complicated by the occurrence of acquired resistance, which emphasizes the need for improved treatment options. Based on a previously reported structure-activity relationship (SAR) study of Spautin-1, which resulted in the discovery of 10a, the search for more potent analogues was envisaged through optimization of the amine substituent. Our search led to the discovery of analogue 15b, harbouring the 2-[4-(4-fluoro-phenoxy)-phenyl]ethylamine substituent, among other potent and original analogues, with nanomolar activity towards EGFR-mutant NSCLC cells. Moreover, this compound 15b showed good selectivity for cancer cells over healthy lung epithelial cells and provides additive effects with food and drug administration (FDA) approved EGFR-tyrosine kinase inhibitors (TKIs), as proven by the co-administration of 15b with Afatinib. Altogether, we report promising lead compounds which show the potential to improve current treatment options.

Thiosemicarbazones and selected tyrosine kinase inhibitors synergize in pediatric solid tumors: NDRG1 upregulation and impaired prosurvival signaling in neuroblastoma cells

Tyrosine kinase inhibitors (TKIs) are frequently used in combined therapy to enhance treatment efficacy and overcome drug resistance. The present study analyzed the effects of three inhibitors, sunitinib, gefitinib, and lapatinib, combined with iron-chelating agents, di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT) or di-2-pyridylketone-4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC). Simultaneous administration of the drugs consistently resulted in synergistic and/or additive activities against the cell lines derived from the most frequent types of pediatric solid tumors. The results of a detailed analysis of cell signaling in the neuroblastoma cell lines revealed that TKIs inhibited the phosphorylation of the corresponding receptor tyrosine kinases, and thiosemicarbazones downregulated the expression of epidermal growth factor receptor, platelet-derived growth factor receptor, and insulin-like growth factor-1 receptor, leading to a strong induction of apoptosis. Marked upregulation of the metastasis suppressor N-myc downstream regulated gene-1 (NDRG1), which is known to be activated and upregulated by thiosemicarbazones in adult cancers, was also detected in thiosemicarbazone-treated neuroblastoma cells. Importantly, these effects were more pronounced in the cells treated with drug combinations, especially with the combinations of lapatinib with thiosemicarbazones. Therefore, these results provide a rationale for novel strategies combining iron-chelating agents with TKIs in therapy of pediatric solid tumors.

Effects of Surgery Combined with Different Chemotherapy on Matrix Metalloproteinase-9 and Tissue Inhibitors of Metalloproteinase-1 in Children with Neuroblastoma

Background

Neuroblastoma (NB) is a common extracranial malignancy in children and accounts for 15% of all cancer-related deaths in children, with the 5-year survival of patients in an advanced stage being lower than 40%. Preoperative adjuvant chemotherapy has been reported to facilitate surgical resection and improve the 2-year survival of patients.

Objective

To analyze the efficacy of surgery plus different chemotherapy on children with NB and to investigate the correlation of matrix metalloproteinase-9 (MMP-9) and tissue inhibitors of metalloproteinase-1 (TIMP-1) with chemotherapy efficacy.

Methods

From April 2005 to May 2017, a total of 92 cases of NB treated in our hospital were assessed for eligibility and recruited. They were assigned at a ratio of 1: 1 to receive either CAV (cyclophosphamide + vincristine + adriamycin) (group A) and EP (etoposide + cisplatin) alternately or TOPO (topotecan) + CTX (cytoxan) + CiE (etoposide + cisplatin) + CPV (cyclophosphamide + pirarubicin + vincristine) (group B). The outcome measures include chemotherapy efficacy, surgical resection rates, complications, 2-year recurrence, and 2-year survival. The levels of NK cells, CD4+/CD8+ cells, MMP-9, TIMP-1, and urine catecholamine (VMA) in peripheral blood of patients before and after initial chemotherapy were determined to analyze the correlation of MMP-9, TIMP-1, and VMA with the efficacy of chemotherapy.

Results

The two groups had similar efficacy (84.00% vs. 95.24%) and surgical resection rates (60.00% vs. 61.90%) after the initial chemotherapy (P > 0.05). Surgery for all eligible patients was successful after second chemotherapy. All eligible patients showed myelosuppression after chemotherapy, including 48 cases with stages I-II (52.17%) and 44 cases with stages III-IV (47.83%). The ratio of CD4+/CD8+ cells, MMP-9, TIMP-1, and VMA expression levels in peripheral blood of patients decreased (P < 0.05) after chemotherapy, and the ratio of CD4+/CD8+ cells was further reduced after surgery (P < 0.05), while natural killer (NK) cells levels increased (P < 0.05). However, intergroup differences were absent in the incidence of myelosuppression, CD4+/CD8+ cell ratio, NK cells, MMP-9, TIMP-1, and VMA expression levels (P > 0.05). MMP-9 and TIMP-1 were positively correlated with VMA (P < 0.05), and the expression levels of MMP-9 and TIMP-1 and VMA after chemotherapy were negatively correlated with chemotherapy efficiency (P < 0.05). Patients with high expressions of MMP-9, TIMP-1, and VMA were associated with lower 2-year survival versus those with low expressions (P < 0.05).

Conclusion

Surgery plus chemotherapy for children with NB yields a promising clinical efficacy and a favorable surgical resection outcome. MMP-9 and TIMP-1 may be the potential biological indicators for chemotherapy efficiency and have a reference value for following surgical treatment of patients.

Molecular basis for cooperative binding and synergy of ATP-site and allosteric EGFR inhibitors

Lung cancer is frequently caused by activating mutations in the epidermal growth factor receptor (EGFR). Allosteric EGFR inhibitors offer promise as the next generation of therapeutics, as they are unaffected by common ATP-site resistance mutations and synergize with the drug osimertinib. Here, we examine combinations of ATP-competitive and allosteric inhibitors to better understand the molecular basis for synergy. We identify a subset of irreversible EGFR inhibitors that display positive binding cooperativity and synergy with the allosteric inhibitor JBJ-04-125-02 in several EGFR variants. Structural analysis of these complexes reveals conformational changes occur mainly in the phosphate-binding loop (P-loop). Mutation of F723 in the P-loop reduces cooperative binding and synergy, supporting a mechanism in which F723-mediated contacts between the P-loop and the allosteric inhibitor are critical for synergy. These structural and mechanistic insights will aid in the identification and development of additional inhibitor combinations with potential clinical value.

Acquired drug resistance is common during chemotherapy. Here, the authors describe the structural basis and molecular mechanism by which allosteric and clinically approved, ATP-competitive inhibitors of EGFR synergize to overcome resistance in lung cancer.

ACY-241, an HDAC6 inhibitor, overcomes erlotinib resistance in human pancreatic cancer cells by inducing autophagy

Histone deacetylase 6 (HDAC6) is a promising target for cancer treatment because it regulates cell mobility, protein trafficking, cell growth, apoptosis, and metastasis. However, the mechanism of HDAC6-induced anticancer drug resistance is unclear. In this study, we evaluated the anticancer effect of ACY-241, an HDAC6-selective inhibitor, on erlotinib-resistant pancreatic cancer cells that overexpress HDAC6. Our data revealed that ACY-241 hyperacetylated the HDAC6 substrate, α-tubulin, leading to a significant reduction in cell viability of erlotinib-resistant pancreatic cells, BxPC3-ER and HPAC-ER. Notably, a synergistic anticancer effect was observed in cells that received combined treatment with ACY-241 and erlotinib. Combined treatment effectively induced autophagy and inhibited autophagy through siLC3B, and siATG5 alleviated ACY-241-mediated cell death, as reflected by the recovery of PARP cleavage and apoptosis rates. In addition, combined ACY-241 and erlotinib treatment induced autophagy and subsequently, cell death by reducing AKT-mTOR activity and increasing phospho-AMPK signaling. Therefore, HDAC6 may be involved in the suppression of autophagy and acquisition of resistance to erlotinib in ER pancreatic cancer cells. ACY-241 to overcome erlotinib resistance could be an effective therapeutic strategy against pancreatic cancer.

Co-delivery of gefitinib and hematoporphyrin by aptamer-modified fluorinated dendrimer for hypoxia alleviation and enhanced synergistic chemo-photodynamic therapy of NSCLC

Although epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs)-based molecular targeted therapy are proved to be effective in the treatment of non-small cell lung cancer (NSCLC) with EGFR mutation, its efficacy is limited by the acquired drug resistance. The combination of EGFR-TKIs with photodynamic therapy (PDT) has been explored to combat NSCLC with promising synergistic results. However, hypoxic tumor microenvironment is associated with the development of EGFR-TKIs resistance and severely limits the efficacy of PDT. Here, we synthesized an aptamer modified fluorinated dendrimer (APF) as a drug carrier and prepared nanocomplexes APFHG by encapsulation of gefitinib (Gef) and hematoporphyrin (Hp). APF has good oxygen-carrying capacity, high drug entrapment efficiency, and could release Gef and Hp in response to intracellular pH. APF can specifically recognize EGFR-positive NSCLC cells and effectively improve the tumor hypoxic microenvironment due to the targeting effect of aptamer and the good oxygen-carrying capacity of the fluorinated dendrimer. Under the laser irradiation, APFHG can significantly increase the production of the intracellular reactive oxygen species and produce a synergistic therapeutic effect in inhibition of cellular growth and induction of cell cycle arrest and apoptosis on both Gef-sensitive and Gef-resistant EGFR-mutant NSCLC cells through PDT/molecular targeted therapy. This work indicates that fluorinated dendrimer could be a potent drug delivery platform to overcome hypoxia-related resistance and the co-delivery of EGFR-TKI and photosensitizer by the fluorinated dendrimer could be a promising therapeutic approach for reversal of EGFR-TKIs resistance in EGFR mutation-positive NSCLC.

Synergistic effects of methyl 2-cyano-3,11-dioxo-18beta-olean-1,-12-dien-30-oate and erlotinib on erlotinib-resistant non-small cell lung cancer cells

Non-small cell lung cancer (NSCLC) is often characterized by an underlying mutation in the epidermal growth factor receptor (EGFR), contributing to aggressive metastatic disease. Methyl 2-cyano-3,11-dioxo-18beta-olean-1,12-dien-30-oate (CDODA-Me), a glycyrrhetinic acid derivative, reportedly improves the therapeutic response to erlotinib (ERL), an EGFR tyrosine kinase inhibitor. In the present study, we performed a series of studies to demonstrate the efficacy of CDODA-Me (2 μM) in sensitizing HCC827R (ERL-resistant) cells to ERL. Herein, we first established the selectivity of ERL-induced drug resistance in the HCC827R cells, which was sensitized when ERL was combined with CDODA-Me (2 μM), shifting the IC50 from 23.48 μM to 5.46 μM. Subsequently, whole transcriptomic microarray expression data demonstrated that the combination of ERL + CDODA-Me elicited 210 downregulated genes (0.44% of the whole transcriptome (WT)) and 174 upregulated genes (0.36% of the WT), of which approximately 80% were unique to the ERL + CDODA-Me group. Synergistic effects centered on losses to cell cycle progression transcripts, a reduction of minichromosome maintenance complex components (MCM2-7), all key components of the Cdc45·MCM2-7GINS (CMG) complex, and replicative helicases; these effects were tantamount to the upregulation of processes associated with the nuclear factor erythroid 2 like 2 translational response to oxidative stress, including sulfiredoxin 1, heme oxygenase 1, and stress-induced growth inhibitor 1. Collectively, these findings indicate that the synergistic therapeutic effects of ERL + CDODA-Me on resistant NSCLC cells are mediated via the inhibition of mitosis and induction of oxidative stress.

Synthesis and Biological Evaluation of (S)-2-(Substituted arylmethyl)-1-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]indole-3-carboxamide Analogs and Their Synergistic Effect against PTEN-Deficient MDA-MB-468 Cells

A series of twenty-six compounds of furfuryl or benzyl tetrahydropyrazino[1,2-a]indole analogs were synthesized and evaluated for cytotoxic activity against the estrogen receptor (ER)-positive breast cancer cell line (MCF-7) and the epidermal growth factor receptor (EGFR) over-expressed triple-negative breast cancer cell line (MDA-MB-468). Among them, compounds 2b, 2f and 2i showed more potent activity and selectivity against MDA-MB-468 cells than gefitinib, as an EGFR- tyrosine kinase inhibitor. In addition, it was confirmed by means of isobologram analysis of combinational treatment with gefitinib that they have a synergistic effect, especially compounds 2b and 2f, which inhibit Akt T308 phosphorylation. Moreover, it was confirmed that 2-benzyl-1-oxo-1,2,3,4-tetrahydropyrazino[1,2-a]indole-3-carboxamide analogs (2b, 2f, and Ref 2) tend to selectively inhibit PI3Kβ, which is involved in the phosphorylation of Akt.

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.

Naphtho-γ-pyrone Dimers from an Endozoic Aspergillus niger and the Effects of Coisolated Monomers in Combination with Cisplatin on a Cisplatin-Resistant A549 Cell Line

Chemotherapy resistance is one of the main causes of lung cancer treatment failure, and a combination regimen may be an effective way to overcome this. Here we report 5 new (1-3, 7, and 9) and 15 known polyketides, isolated from an endozoic Aspergillus niger. The structures of the new compounds were determined by the interpretation of IR, HRESIMS, NMR, and ECD spectra. The ESI-MS/MS fragmentation of the isolated naphtho-γ-pyrone isomers in positive mode is discussed. The effects of isolated compounds in combination with cisplatin (DDP) on a DDP-resistant A549 cell line (A459/DDP) are investigated. The most active compound, 12, could reduce the ratio of GSH/GSSG, promote the generation of intracellular ROS, and cooperate with DDP to down-regulated levels of Nrf2, Akt, HO-1, and NQO1, suggesting that inhibition of Nrf2 and Akt pathways might be involved in the combined effect of 12 and DDP in A549/DDP cells.

The pre-clinical discovery and development of osimertinib used to treat non-small cell lung cancer

Introduction: Osimertinib is currently the only FDA- and EMA-approved third-generation small-molecule epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI). It was initially indicated for second-line treatment of patients with metastatic EGFR T790M mutation-positive non-small cell lung cancer (NSCLC) and got approved for first-line treatment of EGFR activation mutation-positive metastatic NSCLC in 2018. Most recently, the FDA granted approval for the adjuvant treatment of patients with early-stage mutated EGFR NSCLC after tumor resection.Areas covered: This drug discovery case history focuses on the key studies that led to the preclinical discovery and development of osimertinib. The authors focus on published preclinical studies by scientists from AstraZeneca and highlight key events in the clinical development.Expert opinion: Although eventually compromised by the cellular plasticity of the tumor and the inevitable acquisition of drug resistance through the use of osimertinib, its key role in the treatment of NSCLC with specific EGFR mutations will be maintained in the near future. As the genome of EGFR is highly labile and since the rapid development of new mutants remains an issue, there is still room for improvement for the next generation of inhibitors.

MicroRNAs as Therapeutic Targets for Anticancer Drugs in Lung Cancer Therapy

MicroRNAs (miRNAs) are short, non-coding RNA molecules that regulate gene expression by translational repression or deregulation of messenger RNAs. Accumulating evidence suggests that miRNAs play various roles in the development and progression of lung cancers. Although their precise roles in targeted cancer therapy are currently unclear, miRNAs have been shown to affect the sensitivity of tumors to anticancer drugs. A large number of recent studies have demonstrated that some anticancer drugs exerted antitumor activities by affecting the expression of miRNAs and their targeted genes. These studies have elucidated the specific biological mechanism of drugs in tumor suppression, which provides a new idea or basis for their clinical application. In this review, we summarized the therapeutic mechanisms of drugs in lung cancer therapy through their effects on miRNAs and their targeted genes, which highlights the roles of miRNAs as targets in lung cancer therapy.

Role of receptor tyrosine kinases mediated signal transduction pathways in tumor growth and angiogenesis-New insight and futuristic vision

In the past two decades, significant progress has been made in the past two decades towards the understanding of the basic mechanisms underlying cancer growth and angiogenesis. In this context, receptor tyrosine kinases (RTKs) play a pivotal role in cell proliferation, differentiation, growth, motility, invasion, and angiogenesis, all of which contribute to tumor growth and progression. Mutations in RTKs lead to abnormal signal transductions in several pathways such as Ras-Raf, MEK-MAPK, PI3K-AKT and mTOR pathways, affecting a wide range of biological functions including cell proliferation, survival, migration and vascular permeability. Increasing evidence demonstrates that multiple kinases are involved in angiogenesis including RTKs such as vascular endothelial growth factor, platelet derived growth factor, epidermal growth factor, insulin-like growth factor-1, macrophage colony-stimulating factor, nerve growth factor, fibroblast growth factor, Hepatocyte Growth factor, Tie 1 & 2, Tek, Flt-3, Flt-4 and Eph receptors. Overactivation of RTKs and its downstream regulation is implicated in tumor initiation and angiogenesis, representing one of the hallmarks of cancer. This review discusses the role of RTKs, PI3K, and mTOR, their involvement, and their implication in pro-oncogenic cellular processes and angiogenesis with effective approaches and newly approved drugs to inhibit their unrestrained action.

Nano-synergistic combination of Erlotinib and Quinacrine for non-small cell lung cancer (NSCLC) therapeutics - Evaluation in biologically relevant in-vitro models

Non-small cell lung cancer (NSCLC), pre-dominant subtype of lung cancer, is a global disorder affecting millions worldwide. One of the early treatments for NSCLC was use of a first-generation tyrosine kinase inhibitor, Erlotinib (Erlo). However, chronic exposure to Erlo led to development of acquired drug resistance (ADR) in NSCLC, limiting the clinical use of Erlo. A potential approach to overcome development of ADR is a multi-drug therapy. It has been previously reported that Erlo and Quinacrine (QA), an anti-malarial drug, can work synergistically to inhibit tumor progression in NSCLC. However, the combination failed at clinical stages, citing lack of efficacy. In this study, an effort has been made to improve the efficacy of Erlo-QA combination via development of nanoformulations, known to enhance therapeutic efficacy of potent chemotherapies. Synergy between Erlo and QA was measured via estimating the combination indices (CI). It was seen that established combination of nanoformulations (CI: 0.25) had better synergy than plain drug solutions (CI: 0.85) in combination. Following extensive in-vitro testing, data were simulated in biologically relevant 3D tumor models. Two tumor models were developed for extensive in-vitro testing, 3D-Spheroids grown in ultra-low attachment culture plates for efficacy evaluation and a 5D-spheroid model in 5D-sphericalplate with capability of growing 750 spheroids/well for protein expression analysis. Extensive studies on these models revealed that combination of Erlo and QA nanoformulations overall had a better effect in terms of synergy enhancement as compared to plain drug combination. Further, effect of combinatorial therapy on molecular markers was evaluated on 5D-Sphericalplate leading to similar effects on synergy enhancement. Results from present study suggests that combination of nanoformulations can improve the synergy between Erlo and QA while reducing the overall therapeutic dose.

Novel Anti-FOLR1 Antibody-Drug Conjugate MORAb-202 in Breast Cancer and Non-Small Cell Lung Cancer Cells

Antibody-drug conjugates (ADCs), which are currently being developed, may become promising cancer therapeutics. Folate receptor α (FOLR1), a glycosylphosphatidylinositol-anchored membrane protein, is an attractive target of ADCs, as it is largely absent from normal tissues but is overexpressed in malignant tumors of epithelial origin, including ovarian, lung, and breast cancer. In this study, we tested the effects of novel anti-FOLR1 antibody-eribulin conjugate MORAb-202 in breast cancer and non-small cell lung cancer (NSCLC) cell lines. FOLR1 expression, cell proliferation, bystander killing effects, and apoptosis were evaluated in seven breast cancer and nine NSCLC cell lines treated with MORAb-202. Tumor growth and FOLR1 expression were assessed in T47D and MCF7 orthotopic xenograft mouse models after a single intravenous administration of MORAb-202 (5 mg/kg). MORAb-202 was associated with inhibited cell proliferation, with specific selectivity toward FOLR1-expressing breast cancer cell lines. Eribulin, the payload of MORAb-202, was unleashed in HCC1954 cells, diffused into intercellular spaces, and then killed the non-FOLR1-expressing MCF7 cells in co-culture systems. In orthotopic xenograft mouse models, FOLR1-expressing T47D tumors and non-FOLR1-expressing MCF7 tumors were suppressed upon MORAb-202 administration. The novel anti-FOLR1 antibody-eribulin conjugate MORAb-202 has potential antitumor effects in breast cancer.

Epidermal Growth Factor Receptor and its Trafficking Regulation by Acetylation: Implication in Resistance and Exploring the Newer Therapeutic Avenues in Cancer

BACKGROUND

The EGFR is overexpressed in numerous cancers. So, it becomes one of the most favorable drug targets. Single-acting EGFR inhibitors on prolong use induce resistance and side effects. Inhibition of EGFR and/or its interacting proteins by dual/combined/multitargeted therapies can deliver more efficacious drugs with less or no resistance.

OBJECTIVE

The review delves deeper to cover the aspects of EGFR mediated endocytosis, leading to its trafficking, internalization, and crosstalk(s) with HDACs.

METHODS AND RESULTS

This review is put forth to congregate relevant literature evidenced on EGFR, its impact on cancer prognosis, inhibitors, and its trafficking regulation by acetylation along with the current strategies involved in targeting these proteins (EGFR and HDACs) successfully by involving dual/hybrid/combination chemotherapy.

CONCLUSION

The current information on cross-talk of EGFR and HDACs would likely assist researchers in designing and developing dual or multitargeted inhibitors through combining the required pharmacophores.

Recent advances of dual FGFR inhibitors as a novel therapy for cancer

Fibroblast growth factor receptor (FGFR) includes four highly conserved transmembrane receptor tyrosine kinases (FGFR1-4). FGF and FGFR regulate many biological processes, such as angiogenesis, wound healing and tissue regeneration. The abnormal expression of FGFR is related to the tumorigenesis, tumor progression and drug resistance of anti-tumor treatments in many types of tumors. Nowadays there are many anti-cancer drugs targeting FGFR. However, traditional single-target anti-tumor drugs are easy to acquire drug resistance. The therapeutic effect can be enhanced by simultaneously inhibiting FGFR and another target (such as VEGFR, EGFR, PI3K, CSF-1R, etc.). We know drug combination can bring problems such as drug interactions. Therefore, the development of FGFR dual target inhibitors is an important direction. In this paper, we reviewed the research on dual FGFR inhibitors in recent years and made brief comments on them.

Cryptotanshinone strengthens the effect of gefitinib against non-small cell lung cancer through inhibiting transketolase

Lung cancer is the leading cause of cancer-related mortality and causes more than a million deaths per year. Gefitinib is the first-line agent of advanced lung cancer, however, resistance to gefitinib becomes a major problem in clinical application. Transketolase (TKT) is a key enzyme functioning between the oxidative arm and the non-oxidative arm of the pentose phosphate pathway. In this study, we firstly found that the expression of TKT was remarkably up-regulated in NSCLC cells, while the knockdown of TKT could inhibit cell proliferation and enhance the effect of gefitinib on NSCLC cells, which indicated the role of TKT in treating advanced lung cancer. Cryptotanshinone (CTS) is a natural active compound possessing anti-cancer effect. Here we demonstrated that CTS could strengthen the effect of gefitinib on NSCLC cells via inhibition of TKT in vitro and in vivo. Moreover, Nrf2 was involved in the repression of CTS on TKT expression. Collectively, these findings indicated the role of TKT in lung cancer progression and may provide novel therapeutic strategies to overcome resistance to gefitinib. Furthermore, CTS may serve as a new candidate in adjuvant treatment of advanced lung cancer.

Loss of histone lysine methyltransferase EZH2 confers resistance to tyrosine kinase inhibitors in non-small cell lung cancer

Tyrosine kinase inhibitor (TKI) treatment is the first-line therapy for non-small cell lung cancer (NSCLC) caused by activating mutations of epidermal growth factor receptor (EGFR). However, acquired resistance to EGFR-TKI occurs almost inevitably. Aberrant activation of proto-oncogene MET has been known to confer EGFR-TKI resistance; however, the mechanisms involved remains unclear. Recent evidence implicates epigenetic heterogeneity as playing roles in cancer drug resistance, whereas links involving epigenetic heterogeneity and MET in NSCLC remain poorly understood. We found that expression of EZH2, a histone methyltransferase, was negatively correlated with MET activation and EGFR-TKI resistance in NSCLC cells and clinical samples, suggesting the potential for EZH2 to be used as a biomarker for EGFR-TKI sensitivity. Knockdown or inhibition of EZH2 up-regulated MET expression and phosphorylation, and elevated proliferation and EGFR-TKI resistance of cells in vitro. Meanwhile, inhibition of MET or PI3K/AKT enhanced EZH2 levels and restored sensitivity to EGFR-TKI. These findings indicate a "MET-AKT-EZH2" feedback loop regulating EGFR-TKI-resistance. Furthermore, combination therapy of PI3K/AKT inhibition and EGFR-TKI, which interrupts the loop, enhanced tumor-suppressive effects in an EGFR-TKI-resistant xenograft model, indicating a potential approach against drug resistance in NSCLC.

Repurposing loperamide to overcome gefitinib resistance by triggering apoptosis independent of autophagy induction in KRAS mutant NSCLC cells

BACKGROUND

Gefitinib is an epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor (TKI) approved for first-line treatment of non-small cell lung cancer (NSCLC) with sensitizing EGFR mutations. However, NSCLC patients bearing mutant KRAS are inherently unresponsive to gefitinib. Defective autophagy was proposed to mediate resistance to EGFR-TKIs. In this study, the reversal of primary resistance to gefitinib in NSCLC by putative autophagy inducers was investigated.

MATERIALS AND METHODS

A few putative autophagy inducers were investigated in NSCLC cells harboring KRAS or EGFR mutations. Quantitative real-time PCR and Western blot analysis were used to evaluate expression of autophagy-related genes and proteins. Sulforhodamine B assay was used to evaluate cytotoxicity of drug combinations. Flow cytometric asssays were used to study apoptotic and cell cycle effects.

RESULTS

The antidiarrheal agent loperamide was identified as an autophagy inducer. Loperamide promoted the formation of autophagosomes and it potentiated the cytotoxic effect of gefitinib specifically in NSCLC cells bearing mutant KRAS and wild-type EGFR. Gefitinib-loperamide combination enhanced apoptosis and G1 cell cycle arrest, both of which could not be reversed by pharmacological autophagy inhibitor (3-methyladenine). Moreover, synergistic anticancer effect of gefitinib-loperamide combination was observed in both autophagy-proficient (Atg5-wild type) and -deficient (Atg5-knockout) mouse embryonic fibroblasts. Loperamide overcome gefitinib resistance in NSCLC harboring mutant KRAS and wild-type EGFR through increased apoptosis but independent of autophagy induction.

CONCLUSION

Loperamide could be repurposed to overcome primary resistance to gefitinib in KRAS-mutation bearing NSCLC as it also helps relieve the common side effect of diarrhea caused by EGFR-TKIs.

Nanohydroxyapatite-Mediated Imatinib Delivery for Specific Anticancer Applications

In the present study, a nanoapatite-mediated delivery system for imatinib has been proposed. Nanohydroxyapatite (nHAp) was obtained by co-precipitation method, and its physicochemical properties in combination with imatinib (IM) were studied by means of XRPD (X-ray Powder Diffraction), SEM-EDS (Scanning Electron Microscopy-Energy Dispersive X-ray Spectroscopy), FT-IR (Fourier-Transform Infrared Spectroscopy), absorption spectroscopy as well as DLS (Dynamic Light Scattering) techniques. The obtained hydroxyapatite was defined as nanosized rod-shaped particles with high crystallinity. The amorphous imatinib was obtained by conversion of its crystalline form. The beneficial effects of amorphous pharmaceutical agents have been manifested in the higher dissolution rate in body fluids improving their bioavailability. Imatinib-to-hydroxyapatite interactions on the surface were confirmed by SEM images as well as absorption and FT-IR spectroscopy. The cytotoxicity of the system was tested on NI-1, L929, and D17 cell lines. The effectiveness of imatinib was not affected by nHAp modification. The calculated IC₅₀ values for drug-modified nHAp were similar to those for the drug itself. However, higher cytotoxicity was observed at higher concentrations of imatinib, in comparison with the drug alone.

Flavonoids potentiated anticancer activity of cisplatin in non-small cell lung cancer cells in vitro by inhibiting histone deacetylases

AIMS

Cisplatin is the mainstay of first-line treatment for advanced non-small cell lung cancer (NSCLC). Accumulating evidence suggests that flavonoids inhibit histone deacetylase (HDAC) to mediate their anticancer effect in various cancer types. The study was conducted to investigate the inhibition of HDAC and the modulation of apoptotic and cell cycle regulatory genes by selected flavonoids to potentiate the anticancer effect of cisplatin.

MAIN METHODS

Combinations of cisplatin and selected flavonoids were investigated in three NSCLC cell lines (A549, H460, and H1299). Sulforhodamine B assay was used to evaluate cytotoxicity of drug combinations. Western blot analysis was conducted to evaluate histone acetylation. Flow cytometric assays were used to investigate the apoptotic and cell cycle effect. Chromatin immunoprecipitation assay was performed to elucidate the binding of transcription factors to promoters of selected apoptotic and cell cycle regulatory genes.

KEY FINDINGS

Apigenin was found to exhibit the strongest HDAC inhibitory effect among all flavonoids tested. Cisplatin-apigenin combination was shown to produce significantly more S phase prolongation and G2/M cell cycle arrest, and apoptosis compared with cisplatin or apigenin alone, by inducing p21 and PUMA, respectively. More pronounced effect was observed in p53-proficient than p53-null NSCLC cells. Mechanistically, apigenin was found to reduce the binding of HDAC1 but increase the association of RNA polymerase II and Sp1 to p21 and PUMA promoters.

SIGNIFICANCE

Our findings provide a better insight about the mechanism contributing to the HDAC inhibitory effect of apigenin to potentiate anticancer effect of cisplatin by inducing apoptosis and cell cycle arrest.

Antimicrobial peptides: a promising strategy for lung cancer drug discovery?

INTRODUCTION

Antimicrobial peptides (AMPs), also called host defense peptides (HDPs), are identified in almost any form of life, which play an important role in innate immune systems. They have a broad spectrum of antifungal, antiviral, antibacterial, and anticancer activities. Lung cancer remains the leading cause of global cancer-related death. Unfortunately, lung cancer chemotherapy is accompanied by serious side effects, nonspecific toxicity, and multidrug resistance. Hence, to overcome these drawbacks, anticancer peptides (ACPs) derived from AMPs may represent a potential promising synergistic treatment strategy for lung cancer.

AREAS COVERED

In this review, the authors provide the recent advancements in the use of AMPs for the treatment of lung cancer. Furthermore, the anti-lung cancer modes of action of these peptides have been fully reviewed. Importantly, various strategies for increasing the efficiency and safety of AMPs have been discussed.

EXPERT OPINION

The combination of AMPs and other cancer treatment approaches such as chemotherapy, nanoparticle-based delivery systems, and photodynamic therapy can be used as a promising revolutionary strategy for the treatment of lung cancer. The most significant limitations of this strategy that need to be focused on are low efficiency and off-target events.

High-throughput screening reveals higher synergistic effect of MEK inhibitor combinations in colon cancer spheroids

Drug combinations have been proposed to combat drug resistance, but putative treatments are challenged by low bench-to-bed translational efficiency. To explore the effect of cell culture format and readout methods on identification of synergistic drug combinations in vitro, we studied response to 21 clinically relevant drug combinations in standard planar (2D) layouts and physiologically more relevant spheroid (3D) cultures of HCT-116, HT-29 and SW-620 cells. By assessing changes in viability, confluency and spheroid size, we were able to identify readout- and culture format-independent synergies, as well as synergies specific to either culture format or readout method. In particular, we found that spheroids, compared to 2D cultures, were generally both more sensitive and showed greater synergistic response to combinations involving a MEK inhibitor. These results further shed light on the importance of including more complex culture models in order to increase the efficiency of drug discovery pipelines.

Modulating the function of ABCB1: in vitro and in vivo characterization of sitravatinib, a tyrosine kinase inhibitor

BACKGROUND

Overexpression of ATP-binding cassette (ABC) transporter is a major contributor to multidrug resistance (MDR), in which cancer cells acquire resistance to a wide spectrum of chemotherapeutic drugs. In this work, we evaluated the sensitizing effect of sitravatinib, a broad-spectrum tyrosine kinase inhibitor (TKI), on ATP-binding cassette subfamily B member 1 (ABCB1)- and ATP-binding cassette subfamily C member 10 (ABCC10)-mediated MDR.

METHODS

MTT assay was conducted to examine cytotoxicity and evaluate the sensitizing effect of sitravatinib at non-toxic concentrations. Tritium-labeled paclitaxel transportation, Western blotting, immunofluorescence analysis, and ATPase assay were carried out to elucidate the mechanism of sitravatinib-induced chemosensitization. The in vitro findings were translated into preclinical evaluation with the establishment of xenograft models.

RESULTS

Sitravatinib considerably reversed MDR mediated by ABCB1 and partially antagonized ABCC10-mediated MDR. Our in silico docking simulation analysis indicated that sitravatinib strongly and stably bound to the transmembrane domain of ABCB1 human-mouse chimeric model. Furthermore, sitravatinib inhibited hydrolysis of ATP and synchronously decreased the efflux function of ABCB1. Thus, sitravatinib could considerably enhance the intracellular concentration of anticancer drugs. Interestingly, no significant alterations of both expression level and localization of ABCB1 were observed. More importantly, sitravatinib could remarkably restore the antitumor activity of vincristine in ABCB1-mediated xenograft model without observable toxic effect.

CONCLUSIONS

The findings in this study suggest that the combination of sitrvatinib and substrate antineoplastic drugs of ABCB1 could attenuate the MDR mediated by the overexpression of ABCB1.

Recent updates on the resistance mechanisms to epidermal growth factor receptor tyrosine kinase inhibitors and resistance reversion strategies in lung cancer

Epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) have led to a substantial improvement in the prognosis of lung cancer patients by explicitly targeting the activating mutations within the EGFR. Initially, patients harboring tumors with EGFR mutations show progression-free survival and improvement in the response rates toward all-generation EGFR-TKIs; however, these agents fail to deliver the intended results in the long-term due to drug resistance. Therefore, it is necessary to recognize specific cardinal mechanisms that regulate the resistance phenomenon. Understanding the intricate mechanisms underlying EGFR-TKIs resistance in lung cancer could provide cognizance for more advanced targeted therapeutics. The present review features insights into current updates on the discrete mechanisms, including secondary or tertiary mutations, parallel and downstream signaling pathways, acquiring an epithelial-to-mesenchymal transition (EMT) signature, microRNAs (miRNAs), and epigenetic alterations, which lead to intrinsic and acquired resistance against EGFR-TKIs in lung cancer. In addition, this paper also reviews current possible strategies to overcome this issue using combination treatment of recently developed MET inhibitors, allosteric inhibitors or immunotherapies, transformation of EMT, targeting miRNAs, and epigenetic alterations in intrinsic and acquired EGFR-TKIs resistant lung cancer. In conclusion, multiple factors are responsible for intrinsic and acquired resistance to EGFR-TKIs and understanding of the detailed molecular mechanisms, and recent advancements in pharmacological studies are needed to develop new strategies to overcome intrinsic and acquired EGFR-TKIs resistance in lung cancer.

Sitravatinib, a Tyrosine Kinase Inhibitor, Inhibits the Transport Function of ABCG2 and Restores Sensitivity to Chemotherapy-Resistant Cancer Cells in vitro

Sitravatinib, also called MGCD516 or MG-516, is a broad-spectrum tyrosine kinase inhibitor (TKI) under phase III clinical evaluation. Herein, we explored the activity of sitravatinib toward multidrug resistance (MDR) by emphasizing its inhibitory effect on ATP-binding cassette super-family G member 2 (ABCG2). ABCG2 is a member of ATP-binding cassette (ABC) transporter family and plays a critical role in mediating MDR. Sitravatinb received an outstanding docking score for binding to the human ABCG2 model (PDB code: 6ETI) among thirty screened TKIs. Also, an MTT assay indicated that sitravatinib at 3 μM had the ability to restore the antineoplastic effect of various ABCG2 substrates in both drug-selected and gene-transfected ABCG2-overexpressing cell lines. In further tritium-labeled mitoxantrone transportation study, sitravatinib at 3 μM blocked the efflux function mediated by ABCG2 and as a result, increased the intracellular concentration of anticancer drugs. Interestingly, sitravatinib at 3 μM altered neither protein expression nor subcellular localization of ABCG2. An ATPase assay demonstrated that ATPase activity of ABCG2 was inhibited in a concentration-dependent manner with sitravatinib; thus, the energy source to pump out compounds was interfered. Collectively, the results of this study open new avenues for sitravatinib working as an ABCG2 inhibitor which restores the antineoplastic activity of anticancer drugs known to be ABCG2 substrates.

The Role of Exosomal microRNA in Cancer Drug Resistance

Exosomes affect the initiation and progression of cancers. In the tumor microenvironment, not only cancer cells, but also fibroblasts and immunocytes secrete exosomes. Exosomes act as a communicator between cells by transferring different cargos and microRNAs (miRNAs). Drug resistance is one of the critical factors affecting therapeutic effect in the course of cancer treatment. The currently known mechanisms of drug resistance include drug efflux, alterations in drug metabolism, DNA damage repair, alterations of energy programming, cancer stem cells and epigenetic changes. Many studies have shown that miRNA carried by exosomes is closely associated with the development of drug resistance mediated by the above-mentioned mechanisms. This review article will discuss how exosomal miRNAs regulate the drug resistance.

A new epigallocatechin gallate derivative isolated from Anhua dark tea sensitizes the chemosensitivity of gefitinib via the suppression of PI3K/mTOR and epithelial-mesenchymal transition

The acquired resistance to gefitinib limits its clinical application. Epigallocatechin-3-gallate (EGCG) has been found to enhance the efficacy of gefitinib against resistant. However, the cellular and molecular mechanisms have not been completely illuminated in NSCLC. In this study, a new epigallocatechin gallate derivative (2R,3R-6-methoxycarbonylgallocatechin-3-O-gallate, the following referred to as EGCGD) (1) and three known epigallocatechin gallate compounds including epicatechin-3-O-gallate (2), gallocatechin-3-O-gallate (3) and epigallocatechin-3-O-gallate (4, EGCG) were isolated and identified from Anhua dark tea. The pharmacological studies showed EGCGD was more effective against gefitinib-resistant HCC827-Gef cells compared to that of other three epigallocatechin gallate compounds including EGCG, suggesting that introduction of 6-methoxycarbonyl to EGCG might enhance its antitumor activities. Further study on molecular mechanism showed EGCGD increased the potency of gefitinib against HCC827-Gef cells via suppression of epithelial-Mesenchymal transition (EMT) and dual inhibition of PI3K/mTOR.

Development and biological investigations of hypoxia-sensitive prodrugs of the tyrosine kinase inhibitor crizotinib

Despite the huge success of tyrosine kinase inhibitors as anticancer agents, severe side effects are a major problem. In order to overcome this drawback, the first hypoxia-activatable 2-nitroimidazole-based prodrugs of the clinically approved ALK and c-MET inhibitor crizotinib were developed. The 2-aminopyridine functionality of crizotinib (essential for target kinase binding) was considered as ideal position for prodrug derivatization. Consequently, two different prodrugs were synthesized with the nitroimidazole unit attached to crizotinib either via carbamoylation (A) or alkylation (B) of the 2-aminopyridine moiety. The successful prodrug design could be proven by docking studies and a dramatically reduced ALK and c-MET kinase-inhibitory potential. Furthermore, the prodrugs showed high stability in serum and release of crizotinib in an enzymatic nitroreductase-based cleavage assay was observed for prodrug A. The in vitro activity of both prodrugs was investigated against ALK- and c-MET-dependent or -overexpressing cells, revealing a distinct hypoxia-dependent activation for prodrug A. Finally, inhibition of c-MET phosphorylation and cell proliferation could also be proven in vivo. In summary of the theoretical, chemical and biological studies, prodrug derivatization of the 2-aminopyridine position can be considered as a promising strategy to reduce the side effects and improve the anticancer activity of crizotinib.

Lung cancer cells survive epidermal growth factor receptor tyrosine kinase inhibitor exposure through upregulation of cholesterol synthesis

Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) provide clinical benefits over chemotherapy for lung cancer patients with EGFR activating mutations. Despite initial clinical responses, long-term efficacy is not possible because of acquired resistance to these therapies. We have developed EGFR TKI drug-tolerant (DT) human lung cancer cell lines as a model for de novo resistance. Mass spectroscopic analysis revealed that the cytochrome P450 protein, CYP51A1 (Lanosterol 14α-demethylase), which is directly involved with cholesterol synthesis, was significantly upregulated in the DT cells. Total cellular cholesterol, and more specifically, mitochondrial cholesterol, were found to be upregulated in DT cells. We then used the CYP51A1 inhibitor, ketoconazole, to downregulate cholesterol synthesis. In both parental and DT cells, ketoconazole and EGFR TKIs acted synergistically to induce apoptosis and overcome the development of EGFR tolerance. Lastly, this combination therapy was shown to shrink the growth of tumors in an in vivo mouse model of EGFR TKI resistance. Thus, our study demonstrates for the first time that ketoconazole treatment inhibits upregulation of mitochondrial cholesterol and thereby overcomes EGFR-TKI resistance in lung cancer cells.

Discovery of 4,6-pyrimidinediamine derivatives as novel dual EGFR/FGFR inhibitors aimed EGFR/FGFR1-positive NSCLC

FGF2-FGFR1 autocrine pathway activation reduces the sensitivity of non-small cell lung cancer (NSCLC) cells to EGFR inhibitors like Gefitinib. Therefore, dual-specific drugs targeting EGFR and FGFR with high selectivity and activity are required. Through structure analysis of excellent EGFR inhibitors and FGFR inhibitors, we designed and synthesized 33 4,6-pyrimidinediamine derivatives as dual EGFR and FGFR inhibitors and selected BZF 2 as a potential EGFR and FGFR inhibitor after initial cell screening. Then, through kinase testing and western blot analysis, BZF 2 was defined as a dual EGFR and FGFR inhibitor with high selectivity ¹and activity. Biological evaluation of NSCLC cell lines with the FGF2-FGFR1 autocrine loop indicated that BZF 2 significantly inhibited cell proliferation (IC₅₀ values for H226 and HCC827 GR were 2.11 μM, and 0.93 μM, respectively), cell migration, and induced cell apoptosis and cell cycle arrest. Anti-tumor activity test in vivo showed that BZF 2 obviously shrank tumor size. Therefore, BZF 2 is a highly selective and potent dual EGFR/FGFR compound with promising therapeutic effects against EGFR/FGFR1-positive NSCLC.

A novel small-molecule inhibitor of trefoil factor 3 (TFF3) potentiates MEK1/2 inhibition in lung adenocarcinoma

TFF3 has been identified as a novel biomarker to distinguish between lung adenocarcinoma (ADC) and lung squamous-cell carcinoma (SCC). Herein, we determined the oncogenic functions of TFF3 and demonstrated the potential of pharmacological inhibition of TFF3 in lung ADC using a novel small-molecule inhibitor of TFF3 dimerization (AMPC). Forced expression of TFF3 in lung ADC cells enhanced cell proliferation and survival, increased anchorage-independent growth, cancer stem cell behavior, growth in 3D Matrigel, and cell migration and invasion. In contrast, depleted expression of TFF3 suppressed these cellular functions. Mechanistically, TFF3 exerted its oncogenic function through upregulation of ARAF and hence enhanced downstream activation of MEK1/2 and ERK1/2. Pharmacological inhibition of TFF3 by AMPC, resulted in markedly decreased cell survival, proliferation, 3D growth and foci formation, and impaired tumor growth in a xenograft mouse model. Moreover, the combination of various MEK1/2 inhibitors with AMPC exhibited synergistic inhibitory effects on lung ADC cell growth. In conclusion, this study provides the first evidence that TFF3 is a potent promoter of lung ADC progression. Targeting TFF3 with a novel small-molecule inhibitor alone or in combination with conventional MEK1/2 inhibitors are potential strategies to improve the outcome of lung ADC.