Concurrent use of metformin enhances the efficacy of EGFR-TKIs in patients with advanced EGFR-mutant non-small cell lung cancer-an option for overcoming EGFR-TKI resistance

An anti-neoplastic tale of metformin through its transport

Metformin is an attractive candidate drug among all the repurposed drugs for cancer. Extensive preclinical and clinical research has evaluated its efficacy in cancer therapy, revealing a mixed outcome in clinical settings. To fully exploit metformin's therapeutic potential, understanding cellular factors relevant to its transport and accumulation in cancer cells needs to be understood. This review highlights the relevance of metformin transporter status towards its anti-cancer potential. Metformin transporters are regulated at pre-transcriptional, transcriptional, and post-translational levels. Moreover, the tumour microenvironment can also influence metformin accumulation in cancer cells. Also, Metformin treatment can regulate its transporters by altering global DNA methylation, protein acetylation, and transcription factors. Importantly, metformin transporters not only influence chemotherapeutic drug toxicity but are also associated with the prognosis and survival of individuals having cancer. Strategic decisions based on the expression and regulation of metformin transporters holds promise for its therapeutic implications and relevance.

Metformin as anticancer agent and adjuvant in cancer combination therapy: Current progress and future prospect

Metformin, as the preferred antihyperglycemic drug for type 2 diabetes, has been found to have a significant effect in inhibiting tumor growth in recent years. However, metformin alone in cancer treatment has the disadvantages of high dose concentrations and few targeted cancer types. Increasing studies have confirmed that metformin can be used in combination with conventional anticancer therapy to obtain more promising clinical benefits, which is expected to be rapidly transformed and applied in clinic. Some combination therapy strategies including metformin combined with chemotherapy, radiotherapy, targeted therapy and immunotherapy have been proven to have more significant antitumor effects and longer survival time than monotherapy. In this review, we summarize the synergistic antitumor effects and mechanisms of metformin in combination with other current conventional anticancer therapies. In addition, we update the research progress and the latest prospect of the metformin-combined application in the cancer treatment. This work could provide more evidence and future direction for the clinical application of metformin in antitumor.

Effects of metformin on cancers in experimental and clinical studies: Focusing on autophagy and AMPK/mTOR signaling pathways

Metformin (MET) is a preferred drug for the treatment of type 2 diabetes mellitus. Recent studies show that apart from its blood glucose-lowering effects, it also inhibits the development of various tumours, by inducing autophagy. Various studies have confirmed the inhibitory effects of MET on cancer cell lines' propagation, migration, and invasion. The objective of the study was to comprehensively review the potential of MET as an anticancer agent, particularly focusing on its ability to induce autophagy and inhibit the development and progression of various tumors. The study aimed to explore the inhibitory effects of MET on cancer cell proliferation, migration, and invasion, and its impact on key signaling pathways such as adenosine monophosphate-activated protein kinase (AMPK), mammalian target of rapamycin (mTOR), and PI3K. This review noted that MET exerts its anticancer effects by regulating key signalling pathways such as phosphoinositide 3-kinase (PI3K), LC3-I and LC3-II, Beclin-1, p53, and the autophagy-related gene (ATG), inhibiting the mTOR protein, downregulating the expression of p62/SQSTM1, and blockage of the cell cycle at the G0/G1. Moreover, MET can stimulate autophagy through pathways associated with the 5' AMPK, thereby inhibiting he development and progression of various human cancers, including hepatocellular carcinoma, prostate cancer, pancreatic cancer, osteosarcoma, myeloma, and non-small cell lung cancer. In summary, this detailed review provides a framework for further investigations that may appraise the autophagy-induced anticancer potential of MET and its repurposing for cancer treatment.

[Research Progress on Tumor Metabolic Biomarkers in Liquid Biopsy of Lung Cancer]

Liquid biopsy is gradually being applied in the clinical diagnosis and treatment of lung cancer. At present, with the development of metabolomics, more and more metabolic biomarkers are considered as potential sensitive markers reflecting the occurrence and development of tumors. This article summarizes the changes in the main metabolic pathways of lung cancer, including glucose metabolism, amino acid metabolism, lipid metabolism, sphingolipid metabolism, glycerophospholipid metabolism, and purine metabolism. Meanwhile, this article reviews the role of metabolic biomarkers in the early diagnosis of lung cancer, predicting disease progression, and evaluating the efficacy of chemotherapy and immunotherapy, aiming to provide effective biomarkers for tumor diagnosis and treatment.
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Dissecting the genetic variations associated with response to first-line chemotherapy in patients with small cell lung cancer: a retrospective cohort study

Background

Chemotherapy has been the standard treatment for small-cell lung cancer (SCLC) for decades. Nonetheless, patients are usually responsive to initial chemotherapy but quickly suffer from relapse, resulting in a poor long-term outcome. Treating advances that greatly ameliorate survival outcomes are historically finite, and credible biomarkers for therapeutic evaluation are deficient. As the genetic biology emerges, investigating biomarkers to optimize individualized treatment for SCLC is necessary.

Methods

Based on following inclusion criteria: (I) patients diagnosed as SCLC by pathology; (II) patients treated with first-line etoposide/cisplatin (EP) chemotherapy; (III) patients who received long-term follow-up and signed informed consent, a total of 24 SCLC patients receiving first-line standard chemotherapy were divided into progressive disease (PD) and partial response (PR) groups. They were regularly followed every 3 months with computed tomography (CT) scan until recurrences determined by CT scan results. Next-generation sequencing (NGS) with a panel of 1,406 cancer-related genes was conducted on the tumor tissue-derived DNA of patients to compare genetic variations, including deletions (indels), single nucleotide variations (SNVs), copy number variations (CNVs), and copy number instability (CNI) between the two groups.

Results

For the clinical characteristics of enrolled SCLC patients, except for significant differences in sex, age, clinical stage, and limited or extensive stage, PD patients showed distinctly shorter overall survival than those with PR (6.5 vs. 14.0 months, respectively, P=0.007). Genetic variations analysis discovered several common genes with CNV mutations between the PR and PD groups, and increased epidermal growth factor receptor (EGFR) gene copy numbers gain was found in PR groups in comparing with PD patients (P=0.006). However, no significant differences in terms of SNVs, indels, genotypes associated with first-line chemotherapy, CNI of tumor tissue-derived DNA, and tumor mutational burden of tumor tissues were observed between two groups. Additionally, the relationship between EGFR gene mutation and clinicopathological features of SCLC indicated that EGFR gene mutation may be an independent indicator for SCLC patients.

Conclusions

Increased EGFR gene CNVs may be an independent indicator influencing the survival time and PR in SCLC patients receiving standard first-line chemotherapy.

[Research Progress on the Combination Therapy of EGFR-TKIs and Metformin in Acquired Resistance to EGFR-TKIs in Non-small Cell Lung Cancer]

Epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) targeting EGFR are effective in EGFR mutation-positive non-small cell lung cancer (NSCLC) patients, but drug resistance is inevitable. With the application and expansion of individualized and combined therapy, more and more studies have shown that combined administration of Metformin effectively solves the problem of acquired drug resistance to EGFR-TKIs in clinical treatment and prolongs the survival of patients with NSCLC. EGFR-TKIs combined with Metformin is expected to be the treatment method of choice for NSCLC patients with EGFR-TKIs resistance. This paper intends to summarize the research progress of EGFR-TKIs combined with Metformin in the treatment of EGFR-TKIs acquired resistance in NSCLC, in order to provide a new idea for the treatment of NSCLC patients with acquired resistance to EGFR-TKIs.
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Metformin restrains ZIKV replication and alleviates virus-induced inflammatory responses in microglia

The re-emergence of Zika virus (ZIKV) remains a major public health threat that has raised worldwide attention. Accumulating evidence suggests that ZIKV can cause serious pathological changes to the human nervous system, including microcephaly in newborns. Recent studies suggest that metformin, an established treatment for diabetes may play a role in viral infection; however, little is known about the interactions between ZIKV infection and metformin administration. Using fluorescent ZIKV by flow cytometry and immunofluorescence imaging, we found that ZIKV can infect microglia in a dose-dependent manner. Metformin diminished ZIKV replication without the alteration of viral entry and phagocytosis. Our study demonstrated that metformin downregulated ZIKV-induced inflammatory response in microglia in a time- and dose-dependent manner. Our RNA-Seq and qRT-PCR analysis found that type I and III interferons (IFN), such as IFNα2, IFNβ1 and IFNλ3 were upregulated in ZIKV-infected cells by metformin treatment, accompanied with the downregulation of GBP4, OAS1, MX1 and ISG15. Together, our results suggest that metformin-mediated modulation in multiple pathways may attribute to restraining ZIKV infection in microglia, which may provide a potential tool to consider for use in unique clinical circumstances.

Evaluation of Efficacy of ALK Inhibitors According to Body Mass Index in ALK Rearranged NSCLC Patients-A Retrospective Observational Study

No evidence exists as to whether body mass index (BMI) impairs clinical outcomes from ALK inhibitors (ALKi) in patients with ALK-rearranged non-small cell lung cancer (NSCLC). Retrospective data of patients affected by metastatic ALK-rearranged NSCLC treated with ALKi were collected. We divided patients into "low- BMI" (≤25 kg/m²) and "high- BMI" (>25 kg/m²) categories and correlated them with overall survival (OS) and progression-free survival (PFS). We included 40 patients treated with ALKi. We observed a 3-year OS of 81.5% in high-BMI vs. 49.6% in low-BMI categories (p = 0.049); the 3-year first-line PFS was superior in high-BMI vs. low-BMI patients (47% vs. 19%, p = 0.019). As expected, patients treated with Alectinib had a 55.6% 3-year PFS vs. 7.1% for others treated with ALKi (p = 0.025). High-BMI was associated with a 100% 3-year PFS rate vs. 25.4% in low-BMI Alectinib patients (p = 0.03). BMI was independently correlated with first-line PFS and OS at multivariate analysis with PS (HR 0.39, CI 95% 0.16-0.96, p = 0.042; HR 0.18, CI 95% 0.05-0.61, p = 0.006). High-BMI was associated with higher efficacy in ALK-rearranged patients. These results are particularly exciting for Alectinib and could be correlated to mechanisms that should be investigated in subsequent prospective studies.

Low BMI patients with advanced EGFR mutation-positive NSCLC can get a better outcome from metformin plus EGFR-TKI as first-line therapy: A secondary analysis of a phase 2 randomized clinical trial

Background

The synergistic association between metformin and epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitors (TKIs) has been confirmed in in vitro studies. It is still controversial which patients can benefit from metformin plus EGFR-TKIs treatment. Body mass index (BMI) was proved to be independently associated with prolonged progression-free survival (PFS) and overall survival (OS). This study aimed to investigate whether BMI is associated with the synergistic effect of metformin and EGFR-TKIs in advanced EGFR mutation (EGFRm)-positive non-small cell lung cancer (NSCLC) among nondiabetic Asian population.

Methods

We performed a post hoc analysis of a prospective, double-blind phase II randomized clinical trial (COAST, NCT01864681), which enrolled 224 patients without diabetes with treatment-naïve stage IIIB-IV EGFRm NSCLC. We stratified patients into those with a high BMI (≥24 kg/m2) and those with a low BMI (<24 kg/m2) to allow an analysis of the difference in PFS and OS between the two groups. The PFS and OS were analyzed using Kaplan-Meier curves, and the differences between groups were compared using log-rank test.

Results

In the univariate analysis, patients who had a high BMI (n = 56) in the gefitinib + metformin group (n = 28) did not have a better PFS (8.84 months vs. 11.67 months; P = 0.351) or OS (15.58 months vs. 24.36 months; P = 0.095) than those in the gefitinib + placebo group (n = 28). Similar results were also observed in the low-BMI groups. Strikingly, in the metformin plus gefitinib group, patients who had low BMI (n = 69) showed significantly better OS than those with high BMI (24.89 months [95% CI, 20.68 months-not reached] vs. 15.58 months [95% CI, 13.78-31.53 months]; P = 0.007), but this difference was not observed in PFS (10.78 months vs. 8.84 months; P = 0.285).

Conclusions

Our study showed that nondiabetic Asian advanced NSCLC patients with EGFR mutations who have low BMI seem to get better OS from metformin plus EGFR-TKI treatment.

Addition of metformin for non-small cell lung cancer patients receiving antineoplastic agents

Background and purpose: Previous studies have found that metformin can inhibit tumor growth and improve outcomes for cancer patients. However, the association between the addition of metformin to the treatment regimen and survival in non-small cell lung cancer (NSCLC) patients receiving antineoplastic agents such as chemotherapy drugs, epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs), and immune checkpoint inhibitors (ICIs) remains unclear. This study aimed to evaluate the effect of metformin in NSCLC patients who received the aforementioned antineoplastic therapies.

Methods: Several electronic databases were searched for relevant studies published by 10 September 2022. The primary and secondary outcomes were overall survival (OS) and progression-free survival (PFS); eligible studies were those comparing patients with and without the addition of metformin. Hazard ratios (HRs) and 95% confidence intervals (CIs) were combined, with all statistical analyses performed using STATA 15.0.

Results: A total of 19 studies involving 6,419 participants were included, of which six were randomized controlled trials. The overall pooled results indicate that the addition of metformin improved OS (HR = 0.84, 95% CI: 0.71–0.98, p = 0.029) and PFS (HR = 0.85, 95% CI: 0.74–0.99, p = 0.039). However, subgroup analysis based on treatment type and comorbidity of diabetes mellitus demonstrated that improvements in OS and PFS were observed only in diabetic and EGFR-TKI-treated patients (OS: HR = 0.64, 95% CI: 0.45–0.90, p = 0.011; PFS: HR = 0.59, 95% CI: 0.34–1.03, p = 0.061).

Conclusion: Overall, this meta-analysis found that metformin use could improve outcomes for diabetic patients receiving EGFR-TKIs. However, no significant association between the addition of metformin and the survival of non-diabetic NSCLC patients receiving chemotherapy or ICI therapy was identified based on the current evidence.

Inhibition of the AKT1/mTOR pathway through SIRT6 over expression downregulated the expression of programmed death-ligand 1 and prolonged overall survival in lung adenocarcinoma

Background

Programmed death-ligand 1 (PD-L1) is a common biomarker of immune checkpoint inhibitors (ICIs). The purpose of our study was to investigate the relationship between Sirtuin 6 (SIRT6) and PD-L1 expressions in lung adenocarcinoma.

Methods

Recombinant plasmids containing green fluorescent protein (GFP)/no SIRT6 (h-NULL) and GFP/SIRT6 (h-SIRT6) were constructed and transfected into A549 cells by lentivirus as vector. The experiment was divided into control, h-NULL and h-SIRT6 groups. We detected apoptosis and the cell cycle by flow cytometry and observed migration and proliferation by wound-healing assays and methyl thiazolyl tetrazolium. The expressions of SIRT6, PD-L1, serine/threonine protein kinase-1 (AKT1), mammalian target of rapamycin (mTOR), B-cell lymphoma-2 (BCL-2) associated X protein (BAX), and BCL-2 were detected by real-time fluorescence quantitative reverse transcription polymerase chain reaction (qRT-PCR) and Western blot. We retrospectively analyzed the relationship between SIRT6 expression and survival in lung adenocarcinoma treated by ICIs.

Results

The expression of BAX, apoptosis rate, and proportion of G0G1 and G2M phases in the h-SIRT6 group were higher than in the control and h-NULL groups (P<0.05). The expressions of PD-L1, BCL-2, AKT1, and mTOR migration and proliferation rates and proportion of S phase in the h-SIRT6 group were lower than in the control and h-NULL groups (P<0.05). Survival in lung adenocarcinoma with high SIRT6 expression was better than with low SIRT6 expression.

Conclusions

SIRT6 over expression, through the inhibition of the AKT1/mTOR pathway, down-regulated PD-L1 expression, influenced biological behaviors, and prolonged survival of lung adenocarcinoma. SIRT6 expression may be a potential gene biomarker for immunotherapy in lung adenocarcinoma.

Pharmacophore-based virtual screening approaches to identify novel molecular candidates against EGFR through comprehensive computational approaches and in-vitro studies

Alterations to the EGFR (epidermal growth factor receptor) gene, which primarily occur in the axon 18-21 position, have been linked to a variety of cancers, including ovarian, breast, colon, and lung cancer. The use of TK inhibitors (gefitinib, erlotinib, lapatinib, and afatinib) and monoclonal antibodies (cetuximab, panitumumab, and matuzumab) in the treatment of advanced-stage cancer is very common. These drugs are becoming less effective in EGFR targeted cancer treatment and developing resistance to cancer cell eradication, which sometimes necessitates stopping treatment due to the side effects. One in silico study has been conducted to identify EGFR antagonists using other compounds, databases without providing the toxicity profile, comparative analyses, or morphological cell death pattern. The goal of our study was to identify potential lead compounds, and we identified seven compounds based on the docking score and four compounds that were chosen for our study, utilizing toxicity analysis. Molecular docking, virtual screening, dynamic simulation, and in-vitro screening indicated that these compounds' effects were superior to those of already marketed medication (gefitinib). The four compounds obtained, ZINC96937394, ZINC14611940, ZINC103239230, and ZINC96933670, demonstrated improved binding affinity (-9.9 kcal/mol, -9.6 kcal/mol, -9.5 kcal/mol, and -9.2 kcal/mol, respectively), interaction stability, and a lower toxicity profile. In silico toxicity analysis showed that our compounds have a lower toxicity profile and a higher LD50 value. At the same time, a selected compound, i.e., ZINC103239230, was revealed to attach to a particular active site and bind more tightly to the protein, as well as show better in-vitro results when compared to our selected gefitinib medication. MTT assay, gene expression analysis (BAX, BCL-2, and β-catenin), apoptosis analysis, TEM, cell cycle assay, ELISA, and cell migration assays were conducted to perform the cell death analysis of lung cancer and breast cancer, compared to the marketed product. The MTT assay exhibited 80% cell death for 75 µM and 100µM; however, flow cytometry analysis with the IC50 value demonstrated that the selected compound induced higher apoptosis in MCF-7 (30.8%) than in A549.

miR-146 Relieves Acute Asthma via Decreasing Epidermal Growth Factor Receptor/Toll-Like Receptor 4 (EGFR/TLR4) and Enhancing Autophagy

There is a close relationship between acute asthma and autophagy. In addition, some studies claim that miR-146 can regulate autophagy and participate in acute asthma. This study further explores the role of miR-146 in acute asthma and underlying mechanism. Twenty BALB/c mice were selected and randomly divided into two groups, the model group and the control group, each with 10 mice. Lung tissues, peripheral blood, alveolar lavage fluid, and primary lymphocytes were separated into miR-146 over expression group (miR-146 mimic), miR-146 low expression group (miR-146 inhibitor), negative control group (NC), blank group, or SBI-0206965 group. Acute asthma was established and the expression levels of miR-146, EGFR, TLR4, LC3, beclin1, and ATG5 in each group was measured. The targeting relationship and correlation between miR-146 and EGFR were also investigated. The expression of IL-4 in model group was increased compared to control arm while the expression of IFN-γ was opposite (P < 0.05). The expressions of miR-146, LC3, beclin1, and the expression of ATG5 were decreased (P < 0.05). The expressions of miR-146 gene and LC3, beclin1, ATG5 mRNA and protein in the miR-146 mimic group were the highest, while the expressions of EGFR and TLR4 were the lowest. The SBI-0206965 group and the miR-146 inhibitor group are opposite to the miR-146 mimic group, the SBI-0206965 group and the miR-146 inhibitor group have significant differences (P < 0.05). miR-146 has a directly targeted EGFR and TLR4, and both showed a negative correlation (rEGFR=−0.397, P = 0.013; rTLR4=−0.402, P = 0.021). During the onset of asthma, miR-146 was abnormally decreased. miR-146 directly targets and negatively regulates EGFR. In addition, miR-146 down-regulates TLR4 gene to increase CD4+ lymphocytes’ aphagocytosis-related markers (LC3, beclin1, ATG5) which further promotes the autophagy process and ultimately alleviates the degree of acute asthma. Its main mechanism is related to the down-regulation of the EGFR/TLR4 through regulated the expression of autophagy. Our study provided a scientific reference for further understanding of acute pathogenesis of asthma.

Comparison of the efficacy and safety of first-line treatments based on clinicopathological characteristics for patients with advanced epidermal growth factor receptor mutated non-small-cell lung cancer: A systematic review and network meta-analysis

BACKGROUND

A growing number of regimens have been approved as first-line treatments for patients with advanced epidermal growth factor receptor (EGFR) mutated non-small cell lung cancer. However, the optimal regimen has not been determined, especially for patients with different clinicopathological characteristics. Therefore, we performed this meta-analysis to compare the efficacy and safety of first-line treatments for patients with EGFR-mutated NSCLC based on clinicopathological characteristics, thereby providing evidence for individual patient clinical decision-making.

METHODS

The PubMed, Embase, Cochrane Library databases, and abstracts of ASCO, ESMO, and WCLC were searched from inception to 3 June 2021 to identify eligible randomized controlled trials (RCTs). The outcomes of progression-free survival (PFS), overall survival (OS), objective response rate (ORR), and grade 3 or higher adverse events (≥3AEs) were compared and ranked based on various clinicopathological characteristics among 14 regimens by network meta-analysis (NMA) and the surface under the cumulative ranking curve (SUCRA), respectively.

RESULTS

25 RCTs were included, with a total of 6965 patients and 14 treatment regimens. The primary endpoint of all RCTs was PFS, and OS, ORR, and ≥3AEs were secondary endpoints. Regarding overall patients, the most distinct PFS benefit was observed in osimertinib (OSI), with the fewest ≥3AEs, whereas gefitinib plus pemetrexed-based chemotherapy (GEF+PB) provided the greatest benefit for OS. When considering EGFR mutation type, aumolertinib (AUM) and GEF+PB could be the optimal regimens in terms of PFS for patients with EGFR 19DEL and EGFR 21L858R, respectively. Notably, the efficacy of the 14 regimens for PFS varied across clinicopathological characteristics, with GEP+PB ranking first in Eastern Cooperative Oncology Group performance status (ECOG PS)= 1, Asian, age＜65 and smoking subgroups, with AUM ranking first in ECOG PS= 0 and female subgroups, with ICO+PB ranking first in age ≥65 and no smoking subgroups, and with AFA+CET ranking first in the male subgroup. In terms of brain metastases, third-generation EGFR-TKI showed obvious superiority, with AUM and OSI optimally prolonging PFS in patients with and without brain metastases, respectively. In addition, GEF+PB is a superior alternative, ranking second in terms of PFS regardless of the presence of brain metastases.

CONCLUSIONS

OSI and GEF+PB were the most two effective first-line regimens for overall patients, ranking first in PFS and OS, respectively. GEF+PB ranked first in terms of PFS in subgroups of EGFR 21L858R, ECOG PS= 1, Asian, age <65, and smoking. Meanwhile, AUM in subgroups of EGFR 19DEL, ECOG PS= 0, female, brain metastasis, OSI in the subgroup of without brain metastasis, ICO+PB in no smoking subgroup, and AFA+CET in male subgroup were the best options as for their evident superiority in PFS.

Different roles of the insulin-like growth factor (IGF) axis in non-small cell lung cancer

Abstract:

Non-small cell lung cancer (NSCLC) remains one of the deadliest malignant diseases, with high incidence and mortality worldwide. The insulin-like growth factor (IGF) axis, consisting of IGF-1, IGF-2, related receptors (IGF-1R, -2R), and high-affinity binding proteins (IGFBP 1–6), is associated with promoting fetal development, tissue growth, and metabolism. Emerging studies have also identified the role of the IGF axis in NSCLC, including cancer growth, invasion, and metastasis. Upregulation of IGE-1 and IGF-2, overexpression of IGF-1R, and dysregulation of downstream signaling molecules involved in the PI-3K/Akt and MAPK pathways jointly increase the risk of cancer growth and migration in NSCLC. At the genetic level, some noncoding RNAs could influence the proliferation and differentiation of tumor cells through the IGF signaling pathway. The resistance to some promising drugs might be partially attributed to the IGF axis. Therapeutic strategies targeting the IGF axis have been evaluated, and some have shown promising efficacy. In this review, we summarize the biological roles of the IGF axis in NSCLC, including the expression and prognostic significance of the related components, noncoding RNA regulation, involvement in drug resistance, and therapeutic application. This review offers comprehensive understanding of NSCLC and provides insightful ideas for future research.

Metformin induces myeloma cells necrosis and apoptosis and it is considered for therapeutic use

Accumulating evidence, especially in solid tumor, indicated that metformin possessed the potential ability in the proliferation of cancer cells. However, its effects on myeloma cells were relatively rarely clarified. To evaluate the anti-cancer effects of metformin against dexamethasone-resistant and -sensitive myeloma cells. The effects of metformin on myeloma cell lines, including dexamethasone-resistant U266, H929, RPMI 8226 and dexamethasone-sensitive MM.1s, were investigated using the cell counting kit-8 assay for cell proliferation. Apoptosis, necrosis, cell cycle arrest, and cell death mechanisms were explored via flow cytometry (FCM) and Western blot. In addition, the anti-myeloma activity was evaluated in vivo via non-obese diabetic/severe combined immunodeficiency xenograft mouse models. Metformin inhibited proliferation in a dose and time-dependent manner in all the cell lines, while dexamethasone only affected the viability of MM1.s cells. The FCM detection displayed that metformin induced apoptosis in H929, RPMI8226 and MM.1s cells, while for U266 cells, it induced necrosis with Annexin V^-/Propidium iodide⁺. The cell cycle assays showed that metformin arrested G0/G1 phase of H929 and MM.1s cells, or G2/M phase of RPMI8226 cells, but showed no effect on U226 cells. Western blotting analyses demonstrated that the apoptosis-related protein of cleaved caspase 3 was activated; the expressions of Mcl-1, IGF-1R, PI3K, pAKT, and pmTOR proteins were inhibited by metformin in H929, RPMI8226, and MM.1s cells. The necrosis-related protein of iNOS increased in U266 cells while metformin treated. In vivo assay indicated metformin decreased U266 and H929 growth in bone marrow, and thus prolonged mice survival. These data suggested that metformin inhibited the proliferation of myeloma cells via inducing necrosis and apoptosis. This finding indicated that metformin may be served as a potent adjuvant in treating multiple myeloma.

Metformin Enhances TKI-Afatinib Cytotoxic Effect, Causing Downregulation of Glycolysis, Epithelial-Mesenchymal Transition, and EGFR-Signaling Pathway Activation in Lung Cancer Cells

The combination of metformin and TKIs for non-small cell lung cancer has been proposed as a strategy to overcome resistance of neoplastic cells induced by several molecular mechanisms. This study sought to investigate the effects of a second generation TKI afatinib, metformin, or their combination on three adenocarcinoma lung cancer cell lines with different EGFRmutation status. A549, H1975, and HCC827 cell lines were treated with afatinib, metformin, and their combination for 72 h. Afterwards, several parameters were assessed including cytotoxicity, interactions, apoptosis, and EGFR protein levels at the cell membrane and several glycolytic, oxidative phosphorylation (OXPHOS), and EMT expression markers. All cell lines showed additive to synergic interactions for the induction of cytotoxicity caused by the tested combination, as well as an improved pro-apoptotic effect. This effect was accompanied by downregulation of glycolytic, EMT markers, a significant decrease in glucose uptake, extracellular lactate, and a tendency towards increased OXPHOS subunits expression. Interestingly, we observed a better response to the combined therapy in lung cancer cell lines A549 and H1975, which normally have low affinity for TKI treatment. Findings from this study suggest a sensitization to afatinib therapy by metformin in TKI-resistant lung cancer cells, as well as a reduction in cellular glycolytic phenotype.