Gefitinib sensitization of cisplatin-resistant wild-type EGFR non-small cell lung cancer cells

TLE1 corepressor promotes gefitinib resistance in lung cancer A549 cells via E‑cadherin silencing

As a putative lung specific oncogene, the transducin-like enhancer of split 1 (TLE1) corepressor drives an anti-apoptotic and pro-epithelial-mesenchymal transition (EMT) gene transcriptional programs in human lung adenocarcinoma (LUAD) cells, thereby promoting anoikis resistance and tumor aggressiveness. Through its survival- and EMT-promoting gene regulatory programs, TLE1 may impact drug sensitivity and resistance in lung cancer cells. In the present study, a novel function of TLE1 was uncovered as an inhibitor of the antitumor effects of the epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) gefitinib in the human LUAD cell line A549, which exhibits moderate sensitivity to EGFR-TKI. While upregulation of TLE1 expression potently inhibited the proliferation inhibitory and apoptotic effects of gefitinib in A549 cells, downregulation of endogenous TLE1 in these cells enhanced their sensitivity to gefitinib. In experimentally derived gefitinib-resistant A549 cells (A549GR) that have acquired EMT, TLE1 expression is upregulated as compared with parental A549 cells, and acute ablation of TLE1 expression is sufficient to partially restore gefitinib sensitivity and attenuate EMT phenotype. Mechanistic studies showed that TLE1 confers gefitinib resistance in A549 cells in part via downregulation of E-cadherin, a known potentiator of EGFR-TKI sensitivity and apoptosis induction. Importantly, the TLE1/E-cadherin transcriptional axis is negatively regulated by gefitinib to trigger apoptosis via the Bcl-2-inhibitor of transcription 1 cell death pathway. In conclusion, these results indicate a novel role of TLE1 in modulating EGFR-TKI sensitivity in lung cancer cells via regulation of E-cadherin expression, and its upregulation may potentiate EGFR-TKI resistance in LUAD.

TClC effectively suppresses the growth and metastasis of NSCLC via polypharmacology

Despite significant advances in targeted therapies and immunotherapies, non-small cell lung cancer (NSCLC) continues to present a global health challenge, with a modest five-year survival rate of 28 %, largely due to the emergence of treatment-resistant and metastatic tumors. In response, we synthesized a novel bioactive compound, ethyl 6-chlorocoumarin-3-carboxylyl L-theanine (TClC), which significantly inhibited NSCLC growth, epithelial mesenchymal transition (EMT), migration, and invasion in vitro and tumor growth and metastasis in vivo without inducing toxicity. TClC disrupts autocrine loops that promote tumor progression, particularly in stem-like CD133-positive NSCLC (CD133+ LC) cells, which are pivotal in tumor metastasis. Through targeted molecular assays, we identified direct binding targets of TClC, including Akt, NF-κB, β-catenin, EZH2, and PD-L1. This interaction not only suppresses the expression of oncogenic factors and cancer stem cell markers but also downregulates the expression of a multidrug resistance transporter, underscoring the compound's polypharmacological potential. These results position TClC as a promising candidate for NSCLC treatment, signaling a new era in the development of cancer therapies that directly target multiple critical cancer pathways.

Transcription factor PRRX1-activated ANXA6 facilitates EGFR-PKCα complex formation and enhances cisplatin sensitivity in bladder cancer

BACKGROUND

Tumor resistance to cisplatin represents a major clinical challenge, particularly in bladder cancer (BC). ANXA6 is a member of annexin family, and its role in cisplatin resistance remains unclear. This study explores ANXA6's role in promoting cisplatin sensitivity.

METHODS

Bioinformatics analyses and clinical specimen verifications assessed the correlation between ANXA6 and cisplatin treatment. A series of assays, including CCK-8, clone formation assay, flow cytometry assays for reactive oxygen species (ROS) and apoptosis, and comet assays, were used to confirm ANXA6's role in enhancing cisplatin sensitivity and re-sensitizing resistant BC cells. Mass spectrometry, immunofluorescence, and co-immunoprecipitation experiments elucidated ANXA6's role in enhancing PKCα/EGFR complex formation and inhibiting the EGFR pathway. ChIP-PCR and dual-luciferase assays determined PRRX1's regulatory role on ANXA6 transcription. Finally, the impact of ANXA6 in vivo was evaluated using xenograft models.

RESULTS

Bioinformatics analyses showed a significant correlation between ANXA6 expression and cisplatin sensitivity. In vitro and in vivo experiments confirmed that ANXA6 was a new target for cisplatin treatment. ANXA6 overexpression not only enhanced cell viability inhibition, DNA damage and apoptosis caused by cisplatin, but also re-sensitized cisplatin-resistant cells. Mechanistically, ANXA6 promotes PKCα/EGFR complex formation, inhibiting EGFR phosphorylation and downstream AKT and ERK1/2. Moreover, PRRX1 was identified as a transcription factor promoting ANXA6 expression, thereby augmenting the cytotoxic effects of cisplatin.

CONCLUSION

Our study reveals the mechanism by which ANXA6 enhances cisplatin sensitivity and re-sensitizes resistant cells. The roles of PRRX1 and ANXA6 in cisplatin resistance offer new therapeutic targets to overcome cisplatin resistance in clinical practice.

First-line treatment with gefitinib in combination with bevacizumab and chemotherapy in advanced non-squamous NSCLC with EGFR-mutation

BACKGROUND

The safety and efficacy of combination of gefitinib with chemotherapy and bevacizumab in treatment patients with epidermal growth factor receptor (EGFR) mutations are currently unknown. This study was designed to evaluate the safety and preliminary efficacy of a combination therapy consisting of gefitinib, bevacizumab, pemetrexed, and carboplatin in patients with advanced non-squamous non-small cell lung cancer (NSCLC) harboring EGFR mutations.

METHODS

Eligible patients with EGFR-mutated advanced non-squamous NSCLC were recruited and received gefitinib combination with bevacizumab plus pemetrexed and carboplatin treatment. The primary endpoints were safety and progression-free survival (PFS). Secondary endpoints included objective response rate (ORR), disease control rate (DCR), duration of response (DOR), and overall survival (OS).

RESULTS

From June 2019 to June 2021, 20 patients were enrolled in this study. The median follow-up was 33.8 months (95% CI, 31.0-36.6). Grade ≥ 3 adverse events was 65%, including neutropenia (30%), thrombocytopenia (20%), nausea (20%), skin rash (20%), bleeding (10%), and increased ALT (10%). There was no death related to toxicity occurred. The median PFS was 28 months (95% CI, 20.4-35.6). the ORR was 95% (95% CI, 75.1-99.9%), the DCR was 100% (95% CI, 83.2-100%), and the median DOR was 26.4 months (95% CI, 18.9-33.9). The median OS has not been reached.

CONCLUSION

The results of this study demonstrate that the four-drug combination regimen, led by gefitinib, is manageable and tolerated and effective for patients with EGFR-mutated advanced non-squamous NSCLC.

Deguelin Restores Paclitaxel Sensitivity in Paclitaxel-Resistant Ovarian Cancer Cells via Inhibition of the EGFR Signaling Pathway

Background

Ovarian cancer is one of women's malignancies with the highest mortality among gynecological cancers. Paclitaxel is used in first-line ovarian cancer chemotherapy. Research on paclitaxel-resistant ovarian cancer holds significant clinical importance.

Methods

Cell viability and flow cytometric assays were conducted at different time and concentration points of deguelin and paclitaxel treatment. Immunoblotting was performed to assess the activation status of key signaling molecules important for cell survival and proliferation following treatment with deguelin and paclitaxel. The fluo-3 acetoxymethyl assay for P-glycoprotein transport activity assay and cell viability assay in the presence of N-acetyl-L-cysteine were also conducted.

Results

Cell viability and flow cytometric assays demonstrated that deguelin resensitized paclitaxel in a dose- and time-dependent manner. Cotreatment with deguelin and paclitaxel inhibited EGFR and its downstream signaling molecules, including AKT, ERK, STAT3, and p38 MAPK, in SKOV3-TR cells. Interestingly, cotreatment with deguelin and paclitaxel suppressed the expression level of EGFR via the lysosomal degradation pathway. Cotreatment did not affect the expression and function of P-glycoprotein. N-acetyl-L-cysteine failed to restore cell cytotoxicity when used in combination with deguelin and paclitaxel in SKOV3-TR cells. The expression of BCL-2, MCL-1, and the phosphorylation of the S155 residue of BAD were downregulated. Moreover, inhibition of paclitaxel resistance by deguelin was also observed in HeyA8-MDR cells.

Conclusion

Our research showed that deguelin effectively suppresses paclitaxel resistance in SKOV3-TR ovarian cancer cells by downregulating the EGFR and its downstream signaling pathway and modulating the BCL-2 family proteins. Furthermore, deguelin exhibits inhibitory effects on paclitaxel resistance in HeyA8-MDR ovarian cancer cells, suggesting a potential mechanism for paclitaxel resensitization that may not be cell-specific. These findings suggest that deguelin holds promise as an anticancer therapeutic agent for overcoming chemoresistance in ovarian cancer.

Interplay of p62-mTORC1 and EGFR signaling promotes cisplatin resistance in oral cancer

Cisplatin resistance poses a major challenge in the treatment of oral squamous cell carcinoma (OSCC). Deeper investigations into the mechanisms underlying this drug resistance is of great importance. Here, we used cellular assays and clinical immunohistochemistry to examine molecular pathways involved in both innate and acquired cisplatin resistance. We demonstrated that the p62-mTORC1 signaling complex plays a pivotal role, and is driven by the EGFR signaling network, specifically through the PI3K-Akt axis and the transcription factor C/EBP-β. Elevated p-mTOR expression was associated with cancer relapse and poor prognosis among oral cancer patients. Additionally, we illustrated that mTOR inhibitors enhance the cytotoxic effect of cisplatin, by employing cancer stem cell characteristics. Our work unveils fundamental mechanisms for cisplatin resistance, thereby presenting therapeutic implications for OSCC.

Effects of targeted lung cancer drugs on cardiomyocytes studied by atomic force microscopy

The epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKIs) has become one of the important targeted drugs for the treatment of non-small cell lung cancer (NSCLC). But the cardiac adverse events (AEs) related to the EGFR-TKI treatment occur frequently. And the cases of TKI-associated cardiac AEs remain poorly understood. In order to study the effects of EGFR-TKIs on cardiomyocytes, atomic force microscopy (AFM) was used to measure and analyze the physical properties of cardiomyocytes under the actions of three drugs (gefitinib, afatinib and osimertinib) with different concentrations. By comparing the height, adhesion, Young's modulus, the amplitude and the time of the contraction and relaxation process, it was found that the changes of the mechanical properties of cells were well correlated with the symptoms of AEs, such as cardiomyocyte hypertrophy, QT prolongation, atrial fibrillation, ejection fraction reductions, and cardiac failure. In addition, osimertinib has the most obvious effect on cardiomyocytes at a low concentration, and gefitinib has the greatest effect with the increase of concentration, while afatinib has the least effect on cardiomyocytes. This provides a new method for screening drugs and exploring the principle of action in the process of cancer treatment at the cellular level.

NOTCH4ΔL12_16 sensitizes lung adenocarcinomas to EGFR-TKIs through transcriptional down-regulation of HES1

Resistance to epidermal growth factor tyrosine kinase inhibitors (EGFR-TKI) remains one of the major challenges in lung adenocarcinoma (LUAD) therapy. Here, we find an increased frequency of the L12_16 amino acid deletion mutation in the signal peptide region of NOTCH4 (NOTCH4^ΔL12_16) in EGFR-TKI-sensitive patients. Functionally, exogenous induction of NOTCH4^ΔL12_16 in EGFR-TKI -resistant LUAD cells sensitizes them to EGFR-TKIs. This process is mainly mediated by the reduction of the intracellular domain of NOTCH4 (NICD4) caused by the NOTCH4^ΔL12_16 mutation, which results in a lower localization of NOTCH4 in the plasma membrane. Mechanistically, NICD4 transcriptionally upregulates the expression of HES1 by competitively binding to the gene promoter relative to p-STAT3. Because p-STAT3 can downregulate the expression of HES1 in EGFR-TKI-resistant LUAD cells, the reduction of NICD4 induced by NOTCH4^ΔL12_16 mutation leads to a decrease in HES1. Moreover, inhibition of the NOTCH4-HES1 pathway using inhibitors and siRNAs abolishes the resistance of EGFR-TKI. Overall, we report that the NOTCH4^ΔL12_16 mutation sensitizes LUAD patients to EGFR-TKIs through transcriptional down-regulation of HES1 and that targeted blockade of this signaling cohort could reverse EGFR-TKI -resistance in LUAD, providing a potential approach to overcome resistance to EGFR-TKI -therapy.

Synergistic cytotoxicity of the CDK4 inhibitor Fascaplysin in combination with EGFR inhibitor Afatinib against Non-small Cell Lung Cancer

In the absence of suitable molecular markers, non-small cell lung cancer (NSCLC) patients have to be treated with chemotherapy with poor results at advanced stages. Therefore, the activity of the anticancer marine drug fascaplysin was tested against primary NSCLC cell lines established from pleural effusions. Cytotoxicity of the drug or combinations were determined using MTT assays and changes in intracellular phosphorylation by Western blot arrays. Fascaplysin revealed high cytotoxicity against NSCLC cells and exhibit an activity pattern different of the standard drug cisplatin. Furthermore, fascaplysin synergizes with the EGFR tyrosine kinase inhibitor (TKI) afatinib to yield a twofold increased antitumor effect. Interaction with the Chk1/2 inhibitor AZD7762 confirm the differential effects of fascplysin and cisplatin. Protein phosphorylation assays showed hypophosphorylation of Akt1/2/3 and ERK1/2 as well as hyperphosphorylation of stress response mediators of H1299 NSCLC cells. In conclusion, fascaplysin shows high cytotoxicity against pleural primary NSCLC lines that could be further boosted when combined with the EGFR TKI afatinib.

BEZ235 reduction of cisplatin resistance on wild-type EGFR non-small cell lung cancer cells

Cisplatin, as a first-line chemotherapy drug for advanced wild-type epidermal growth factor receptor (wtEGFR) non-small cell lung cancer (NSCLC), often loses effectiveness because of acquired drug resistance. We found that ataxia-telangiectasia mutated (ATM), ataxia-telangiectasia and Rad3-related (ATR) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) of DNA repair kinases and signal transduction molecules, protein kinase B (AKT)/target mammalian target of rapamycin (mTOR), were significantly phosphorylated in cisplatin-resistant wtEGFR NSCLC cell lines (H358R and A549R) than in their parental cells. Also, BEZ235 (dual phosphatidylinositol-3-kinase (PI3K)/mTOR inhibitor) significantly decreased the phosphorylation levels of these kinases/proteins, as detected by Western blot analysis. In H358R and A549R cells, the results of indirect immunofluorescence, single-cell gel electrophoresis, flow cytometry, methylthiazolyldiphenyl-tetrazolium bromide, clone formation assay, and scratch healing experiment showed that BEZ235 enhanced cisplatin-induced DNA damage and cell apoptosis, and effectively inhibited cellular proliferation/migration when combined with cisplatin. The data indicated that the abnormal activation of ATM/ATR/DNA-PKcs kinases and AKT/mTOR pathway might induce wtEGFR NSCLC cell resistance to cisplatin. The effects of the combination of BEZ235 and cisplatin suggested that BEZ235 should be considered as a combination therapy for patients with cisplatin-resistant wtEGFR NSCLC.

Autophagy up-regulated by MEK/ERK promotes the repair of DNA damage caused by aflatoxin B1

Aflatoxin B1 (AFB1), a kind of mycotoxin, exerts its cytotoxicity by increasing the oxidative damage of target organs, especially the liver. In vivo and in vitro experiments were carried out to elucidate the toxic mechanism of AFB1. The results of MTT, cloning-formation, flow cytometry, immunocytochemistry, Reverse transcription PCR (RT-PCR) and western blot showed that AFB1 activated NOX2 gp91 phox, inhibited proliferation and migration, and blocked cell cycle at G0/G1 period of HHL-5 cells. Autophagy promoted the repair of NOX2-dependent DNA damage. NOX2/gp91 phox mainly activates MEK/ERK pathway and then up-regulates autophagy. In vivo experiments have shown that AFB1 (0.75 mg/kg daily orally, 4 weeks) had no significant changes in the size and shape of the liver in mice. However, these treatments lead to structural abnormalities of hepatocytes and DNA damage. In summary, AFB1 caused intracellular oxidative stress and DNA damage, NOX2/gp91-phox activates the MEK/ERK pathway, and upregulated autophagy to promote the repair of DNA damage. We concluded that by increasing the level of autophagy, the ability of anti-AFB1 toxicity of liver can be increased.

Induction of Apoptosis and Inhibition of EGFR/NF-κB Signaling Are Associated With Regorafenib-sensitized Non-small Cell Lung Cancer to Cisplatin

BACKGROUND/AIM

The combination of regorafenib with cisplatin/pemetrexed has indicated controllable safety and encouraging antitumor activity in non-small cell lung cancer (NSCLC) patients. However, the anti-NSCLC effects and action mechanisms of regorafenib combined with cisplatin is ambiguous. The major goal of the study was to study the inhibitory effects and action mechanisms of regorafenib combined with cisplatin in NSCLC cells.

MATERIALS AND METHODS

Cell viability, flow cytometry, immunofluorescence staining, western blotting, migration, and invasion assays were employed to verify the anti-NSCLC effects and mechanisms of regorafenib in combination with cisplatin.

RESULTS

Cisplatin-induced epidermal growth factor receptor (EGFR)/nuclear factor κB (NF-κB) signaling was effectively inhibited by regorafenib treatment. Regorafenib, erlotinib (EGFR inhibitor) and QNZ (NF-κB inhibitor) may all enhance the cytotoxicity effect of cisplatin. The invasion ability was effectively decreased by combination treatment. Caspase-dependent and -independent apoptosis was activated by cisplatin combined with regorafenib.

CONCLUSION

Apoptosis induction and EGFR/NF-κB inactivation correlate with regorafenib-enhanced anti-NSCLC efficacy of cisplatin. This study provides evidence of the therapeutic efficacy of regorafenib in combination with cisplatin on NSCLC.

Epidermal growth factor receptor promotes tumor progression and contributes to gemcitabine resistance in osteosarcoma

Osteosarcoma (OS) is the most common type of primary malignant tumors that originate in the bone. Resistance to chemotherapy confers a poor prognosis on OS patients. Dysregulation of the epidermal growth factor receptor (EGFR) signaling has been reported in sarcomas. However, the functional contribution of EGFR hyperactivation to the tumor biology and chemoresistance remains largely unexplored in OS. In this study, we aimed to investigate the role of EGFR in OS progression and in the response of OS to gemcitabine treatment. The EGFR expression was found to be upregulated in fibroblastic OS cell lines. EGFR knockdown suppressed OS cell proliferation, migration, and invasion in vitro and tumor formation in vivo. Conversely, EGFR overexpression promoted the growth and motility of OS cells. In terms of mechanism, the levels of phospho-Akt and phospho-ERK were decreased upon EGFR knockdown but increased as a result of EGFR overexpression, implying a possible involvement of PI3K/Akt and ERK pathways in mediating the effects of EGFR on OS cells. Moreover, the level of phospho-EGFR was increased in OS cells when exposed to gemcitabine treatment. A more profound proliferative inhibition and a higher rate of apoptosis were obtained in OS cells via inducing cell cycle arrest at G1 phase upon gemcitabine treatment combined with EGFR knockdown, as compared to gemcitabine alone. On the contrary, EGFR overexpression counteracted the growth-inhibiting and pro-apoptotic effects of gemcitabine in OS cells. The present study suggests that EGFR promotes tumor progression and contributes to gemcitabine resistance in OS.

Functional loss of TAGLN inhibits tumor growth and increases chemosensitivity of non-small cell lung cancer

Non-small cell lung cancer (NSCLC) is the leading cause of tumor mortality worldwide. However, the mechanisms underlying NSCLC tumorigenesis are incompletely understood. TAGLN, also named SM22, as a member of the calponin family, is highly expressed in many types of tumors. Nevertheless, its effects on NSCLC progression remain unclear. In this study, we found that TAGLN was over-expressed in tumor tissues of NSCLC patients and cell lines. Additionally, NSCLC patients with high expression showed worse overall survival rate. Then, gene silencing results indicated that TAGLN knockdown markedly inhibited proliferation and induced apoptosis in NSCLC cells, while rescue study exhibited opposite results. Moreover, suppressing TAGLN significantly reduced migration and invasion of NSCLC cells, and its over-expression promoted the migratory and invasive activities of NSCLC cells. The in vivo studies confirmed the oncogenic roles of TAGLN in NSCLC, along with clearly elevated metastasis. Notably, these effects were abrogated in mice with TAGLN deletion. Finally, we found that TAGLN knockdown could improve the sensitivity of NSCLC cells to sorafenib (SFB) and 5-FU treatment, further suppressing the proliferation, migration and invasion of NSCLC cells. Consistently, TAGLN deletion attenuated tumor xenografts growth and metastasis of NSCLC in mouse models by enhancing the anti-cancer effects of SFB and 5-FU. Altogether, these findings demonstrated that TAGLN functioned as an oncogene as well as a chemotherapeutic regulator during NSCLC development, which suggested a potential therapeutic strategy for NSCLC treatment mainly through repressing TAGLN expression.