Downregulation of both EGFR and ErbB3 improves the cellular response to pemetrexed in an established pemetrexed‑resistant lung adenocarcinoma A549 cell line

SP3-induced Timeless transcription contributes to cell growth of lung adenocarcinoma cells

BACKGROUND

Timeless is well-known for its key role in replication checkpoints. Recent studies reveal the involvement of Timeless and specificity protein (SP) 1 in human malignancies. However, no evidence proved the interaction between SP3 and Timeless in lung adenocarcinoma (LUAD).

METHODS

The expression and clinical significance of Timeless were analyzed using the LUAD dataset downloaded from the Cancer Genome Atlas (TCGA). Lentivirus-mediated Timeless knockdown in A549 cells was used to examine the role of Timeless in cell proliferation and pemetrexed (PEM) resistance. Transcription factors (TFs) bound to the Timeless promoter were identified by DNA pull-down technology with HPLC-MS/MS analysis and analyzed by the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway. Dual-luciferase reporter assay was used to determine the activity of SP3 in Timeless transcription.

RESULTS

Timeless was overexpressed in LUAD samples, and it could serve as a potential diagnostic or prognostic biomarker for LUAD patients. shTimeless-mediated knockdown of Timeless reduced cell viability and proliferation and sensitized PEM-resistant A549 cells to PEM. Four fragments (F1: 1-373 bp), (F2: 374-962 bp), (F4: 1274-1645 bp), and (F5: 1646-2000bp) were confirmed as the TF binding profiles of the Timeless promoter. KEGG analysis showed that the TFs bound to the Timeless promoter had relevance to spliceosome, RNA transport, and mRNA surveillance pathways. SP3 promoted the transcription of Timeless via the F2 fragment (374-962 bp) binding motif.

CONCLUSION

Upregulation of Timeless mediated by SP3 promotes LUAD cell proliferation, providing evidence to support that targeting the SP3/Timeless axis may be a potential therapeutic strategy against LUAD.

Investigation of HER-3 gene expression under the influence of carbohydrate biopolymers extract of shiitake and reishi in MCF-7 cell line

INTRODUCTION

Edible-medicinal fungi are mainly used in Asian countries to prevent various diseases. These mushrooms are also used to treat lung diseases and cancer. Ganoderma lucidum and Lentinula edodes are the most important edible-medicinal fungi. The polysaccharides of these fungi are one of the bioactive compounds with anti-cancer properties.

OBJECTIVE

Evaluation of anti-cancer effects of Shiitake and Reishi polysaccharides.

METHODS

In this study, fungal polysaccharides were extracted using the hot water method and were purified by Diethylaminoethyl Sephadex A-25 (DEAE-Sephadex A-25) chromatography column and their concentration was measured by phenolic sulfuric acid method. The biological effects of the extracted polysaccharides from Ganoderma lucidum and Lentinula edodes on the MCF-7 cell line were investigated using an MTT assay and then its effects on the expression of the P53 cancer regulatory gene and HER-3 gene were investigated.

RESULTS

Based on the results, the concentration of Ganoderma lucidum and Lentinula edodes extracted polysaccharides were 0.024 and 0.103 mg/ml, respectively. Polysaccharides of these two fungi increased the expression of the P53 gene and decreased the expression of the HER-3 gene in a dose and time-dependent manner.

DISCUSSION

Natural biocompatible polysaccharides with anti-cancer properties that are native, are available, and inexpensive, so they can be used as dietary supplements to prevent and help treat cancer.

Mechanisms of resistance to chemotherapy in non-small cell lung cancer

Non-small cell lung cancer (NSCLC), which represents 80-85% of lung cancer cases, is one of the leading causes of human death worldwide. The majority of patients undergo an intensive and invasive treatment regimen, which may include radiotherapy, chemotherapy, targeted therapy, immunotherapy, or a combination of these, depending on disease stage and performance status. Despite advances in therapeutic regimens, the 5-year survival of NSCLC is approximately 20-30%, largely due to diagnosis at advanced stages. Conventional chemotherapy is still the standard treatment option for patients with NSCLC, especially those with advanced disease. However, the emergence of resistance to chemotherapeutic agents (chemoresistance) poses a significant obstacle to the management of patients with NSCLC. Therefore, to develop efficacious chemotherapeutic approaches for NSCLC, it is necessary to understand the mechanisms underlying chemoresistance. Several mechanisms are known to mediate chemoresistance. These include altered cellular targets for chemotherapy, decreased cellular drug concentrations, blockade of chemotherapy-induced cell cycle arrest and apoptosis, acquisition of epithelial-mesenchymal transition and cancer stem cell-like phenotypes, deregulated expression of microRNAs, epigenetic modulation, and the interaction with tumor microenvironments. In this review, we summarize the mechanisms underlying chemoresistance and tumor recurrence in NSCLC and discuss potential strategies to avoid or overcome chemoresistance.

HER3-Receptor-Mediated STAT3 Activation Plays a Central Role in Adaptive Resistance toward Vemurafenib in Melanoma

Simple Summary

The major obstacle for the long-term success of targeted therapies in melanoma is the occurrence of resistance. Here, we present a new mechanism of targeted therapy resistance in melanoma where the treatment with the BRAF inhibitor vemurafenib causes an increased activation of HER3 via shed ligands. This is followed by an activation of STAT3 via HER3 and results in the expression of the STAT3 target gene SOX2. Pharmacological inhibition of HERs sensitizes melanoma cells toward vemurafenib treatment. Thus, blocking HER family members and especially HER3 in addition to targeted therapy treatment might prevent the occurrence of resistance.

Abstract

Melanoma is an aggressive form of skin cancer that is often characterized by activating mutations in the Mitogen-Activated Protein (MAP) kinase pathway, causing hyperproliferation of the cancer cells. Thus, inhibitors targeting this pathway were developed. These inhibitors are initially very effective, but the occurrence of resistance eventually leads to a failure of the therapy and is the major obstacle for clinical success. Therefore, investigating the mechanisms causing resistance and discovering ways to overcome them is essential for the success of therapy. Here, we observed that treatment of melanoma cells with the B-Raf Proto-Oncogene, Serine/Threonine Kinase (BRAF) inhibitor vemurafenib caused an increased cell surface expression and activation of human epidermal growth factor receptor 3 (HER3) by shed ligands. HER3 promoted the activation of signal transducer and activator of transcription 3 (STAT3) resulting in upregulation of the STAT3 target gene SRY-Box Transcription Factor 2 (SOX2) and survival of the cancer cells. Pharmacological blocking of HER led to a diminished STAT3 activation and increased sensitivity toward vemurafenib. Moreover, HER blocking sensitized vemurafenib-resistant cells to drug treatment. We conclude that the inhibition of the STAT3 upstream regulator HER might help to overcome melanoma therapy resistance toward targeted therapies.

The deubiquitinating enzyme UCHL1 promotes resistance to pemetrexed in non-small cell lung cancer by upregulating thymidylate synthase

Rationale: Resistance to pemetrexed (PEM)-based chemotherapy is a major cause of progression in non-small cell lung cancer (NSCLC) patients. The deubiquitinating enzyme UCHL1 was recently found to play important roles in chemoresistance and tumor progression. However, the potential roles and mechanisms of UCHL1 in PEM resistance remain unclear.

Methods: Bioinformatics analyses and immunohistochemistry were used to evaluate UCHL1 expression in NSCLC specimens. Kaplan-Meier analysis with the log-rank test was used for survival analyses. We established PEM-resistant NSCLC cell lines by exposing them to step-wise increases in PEM concentrations, and in vitro and in vivo assays were used to explore the roles and mechanisms of UCHL1 in PEM resistance using the NSCLC cells.

Results: In chemoresistant tumors from NSCLC patients, UCHL1 was highly expressed and elevated UCHL1 expression was strongly associated with poor outcomes. Furthermore, UCHL1 expression was significantly upregulated in PEM-resistant NSCLC cells, while genetic silencing or inhibiting UCHL1 suppressed resistance to PEM and other drugs in NSCLC cells. Mechanistically, UCHL1 promoted PEM resistance in NSCLC by upregulating the expression of thymidylate synthase (TS), based on reduced TS expression after UCHL1 inhibition and re-emergence of PEM resistance upon TS restoration. Furthermore, UCHL1 upregulated TS expression, which mitigated PEM-induced DNA damage and cell cycle arrest in NSCLC cells, and also conferred resistance to PEM and other drugs.

Conclusions: It appears that UCHL1 promotes PEM resistance by upregulating TS in NSCLC cells, which mitigated DNA damage and cell cycle arrest. Thus, UCHL1 may be a therapeutic target for overcoming PEM resistance in NSCLC patients.

Mechanisms of resistance to pemetrexed in non-small cell lung cancer

Currently, lung cancer has remained the most common cause of cancer death while non-small cell lung cancer (NSCLC) accounts for the most of all lung cancer cases. Regardless of multiple existing managements, chemotherapy regimens are still the mainstay of treatment for NSCLC, where pemetrexed has shown cytotoxic activity and has increasingly been used, especially for advanced cases. However, chemo-resistance may inhibit clinical efficacy after long-term use. Mechanisms responsible for chemo-resistance to pemetrexed in NSCLC are plethoric but can be separated into two categories to be discussed: tumor cells and their interactions with drugs. Phenomena relevant to tumor cells such as oncogene or oncoprotein alterations, DNA synthesis, DNA repair, and tumor cell biology behavior are discussed, as well as processes associated with drug dynamics, including drug uptake, drug elimination, and antifolate polyglutamylation. This review will focus on clinical trials and the basic biomedical mechanisms of NSCLC treated with pemetrexed and will describe the underlying mechanisms of resistance to facilitate more efficient clinical therapies to treat patients.

Design, Synthesis and Antitumor Activity of Quinazoline Derivatives Bearing 2,3-Dihydro-indole or 1,2,3,4-Tetrahydroquinoline

Background:

Cancer continues to pose a great problem and burden on society despite new treatment options. While surgery, radiotherapy, and chemotherapy have led to major improvements in patient prognosis, newer treatments are needed to more effectively manage this disease in its advanced stage. Epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase (RTK), which is catalytically active and under tight regulatory control. Dysregulation of its activity is strongly associated with tumorigenesis and cancer patients with altered EGFR activity tend to have a more aggressive disease, associated with a poor clinical prognosis. The family of EGFR has been intensively studied due to its strong influence on the formulation and deterioration of carcinoma. Thus, it is a good strategy that design anticancer agents by inhibiting the EGFR pathway.

Methods:

We group to obtain the six series compounds (8a-f, 9a-f, 10a-f, 11a-f, 12a-b and 13a-d). Hence we disclosed the design, synthesis and antitumor activity of novel quinazoline analogues against EGFR overexpression cancer cells A549 (human lung cancer), HepG-2 (human liver cancer), MCF-7 (human breast cancer) and PC-3 (human prostate cancer) and as well as the inhibitory on EGFR kinase. Moreover, apoptosis by acridine orange single staining and docking studies were presented in this paper as well.

Results:

Six series of quinazoline derivatives bearing 2,3-dihydro-indole or 1,2,3,4-tetrahydroquinoline (8a-f, 9a-f, 10a-f, 11a-f, 12a-b and 13a-d) were designed, synthesized and evaluated for the half maximal inhibitory concentration (IC50) values against four cancer cell lines (A549, HepG-2, MCF-7 and PC-3). Thirty target compounds showed moderate to excellent (1.49 - 50 µM) cytotoxicity activity against one or several cancer cell lines. The compound 13a showed the best activity against A549, HepG- 2, MCF-7 and PC-3 cancer cell lines, with the IC50 values of 1.49 ± 0.17 µM, 2.90 ± 0.24 µM, 1.85 ± 0.19 µM, 3.30 ± 0.22 µM, respectively. What’s more, the secondary amines were introduced to the target compounds to improve the water-soluble. The results showed that the compounds were beneficial to the cytotoxicity activity. Furthermore, the results prompted us that this series of compounds may be a kind of potential epidermal growth factor receptor (EGFR) kinase inhibitors.

Conclusion:

Six series of quinazoline derivatives bearing 2,3-dihydro-indole or 1,2,3,4- tetrahydroquinoline moiety (8a-f, 9a-f, 10a-f, 11a-f, 12a-b and 13a-d) were designed, synthesized and evaluated for the IC50 values of cytotoxicity against four cancer cell lines (A549, HepG-2, MCF-7 and PC-3). Thirty synthesized compounds showed moderate to excellent cytotoxicity activity against the different cancer cells. Especially, the compound 13a exerted antitumor effects in a dosage-dependent manner and the IC50 values of compound 13a were 1.49 µM, 2.90 µM, 1.85 µM and 3.30 µM against A549, HepG-2, MCF-7 and PC-3, respectively. From the antitumor activity data show that the compounds possessed selectivity for A549 and MCF-7 cancer cell lines. It meant that the compounds had better treatment effect on lung cancer and breast cancer. On the whole, the compounds substituted by 1,2,3,4-tetrahydroquinoline at C-4 position of quinazoline and (S)-tetrahydrofuran-3-ol at C-8 position of quinazoline were beneficial to the cytotoxicity activity. From the result of acridine orange (AO) single staining which indicated the compound 13a could induce apoptosis of A549 cells. From the result of Docking Studies, we hypothesized that the C-4 position of quinazoline were substituted by 2,3-dihydro-indole or 1,2,3,4-tetrahydroquinoline with the equal influence of the cytotoxicity activity. Overall, the results prompted us that this series of compounds may be a kind of potential EGFR kinase inhibitors.

Design, synthesis, antiproliferative activity and docking studies of quinazoline derivatives bearing oxazole or imidazole as potential EGFR inhibitors

Six series of quinazoline derivatives bearing oxazole or imidazole (8a–f, 9a–f, 10a–d, 11a–f, 12a–d and 13a–i) were designed, synthesized and their IC₅₀ values evaluated against three cancer cell lines (A549, MCF-7 and PC-3).

Augmented expression of cardiac ankyrin repeat protein is induced by pemetrexed and a possible marker for the pemetrexed resistance in mesothelioma cells

Background

Pemetrexed (PEM) is an anti-cancer agent targeting DNA and RNA synthesis, and clinically in use for mesothelioma and non-small cell lung carcinoma. A mechanism of resistance to PEM is associated with elevated activities of several enzymes involved in nucleic acid metabolism.

Methods

We established two kinds of PEM-resistant mesothelioma cells which did not show any increase of the relevant enzyme activities. We screened genes enhanced in the PEM-resistant cells with a microarray analysis and confirmed the expression levels with Western blot analysis. A possible involvement of the candidates in the PEM-resistance was examined with a WST assay after knocking down the expression with si-RNA. We also analyzed a mechanism of the up-regulated expression with agents influencing AMP-activated protein kinase (AMPK) and p53.

Results

We found that expression of cardiac ankyrin repeat protein (CARP) was elevated in the PEM-resistant cells with a microarray and Western blot analysis. Down-regulation of CARP expression with si-RNA did not however influence the PEM resistance. Parent and PEM-resistant cells treated with PEM increased expression of CARP, AMPK, p53 and histone H2AX. The CARP up-regulation was however irrelevant to the p53 genotypes and not induced by an AMPK activator. Augmented p53 levels with nutlin-3a, an inhibitor for p53 degradation, and DNA damages were not always associated with the enhanced CARP expression.

Conclusions

These data collectively suggest that up-regulated CARP expression is a potential marker for development of PEM-resistance in mesothelioma and that the PEM-mediated enhanced expression is not directly linked with immediate cellular responses to PEM.

Electronic supplementary material

The online version of this article (10.1186/s12935-017-0493-8) contains supplementary material, which is available to authorized users.