Metformin promotes survivin degradation through AMPK/PKA/GSK-3β-axis in non-small cell lung cancer

Preclinical evidence using synthetic compounds and natural products indicates that AMPK represents a potential pharmacological target for the therapy of pulmonary diseases

Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) is a highly conserved eukaryotic enzyme discovered as a key regulator of cellular energy homeostasis, with anti-inflammation, antioxidative stress, anticancer, and antifibrosis beneficial effects. AMPK is dysregulated in human pulmonary diseases such as acute lung injury, nonsmall cell lung cancer, pulmonary fibrosis, chronic obstructive pulmonary disease, and asthma. This review provides an overview of the beneficial role of natural, synthetic, and Chinese traditional medicines AMPK modulators in pulmonary diseases, and highlights the role of the AMPK signaling pathway in the lung, emphasizing the importance of finding lead compounds and drugs that can target and modulate AMPK to treat the lung diseases.

Heterogeneity and interplay: the multifaceted role of cancer-associated fibroblasts in the tumor and therapeutic strategies

The journey of cancer development is a multifaceted and staged process. The array of treatments available for cancer varies significantly, dictated by the disease's type and stage. Cancer-associated fibroblasts (CAFs), prevalent across various cancer types and stages, play a pivotal role in tumor genesis, progression, metastasis, and drug resistance. The strategy of concurrently targeting cancer cells and CAFs holds great promise in cancer therapy. In this review, we focus intently on CAFs, delving into their critical role in cancer's progression. We begin by exploring the origins, classification, and surface markers of CAFs. Following this, we emphasize the key cytokines and signaling pathways involved in the interplay between cancer cells and CAFs and their influence on the tumor immune microenvironment. Additionally, we examine current therapeutic approaches targeting CAFs. This article underscores the multifarious roles of CAFs within the tumor microenvironment and their potential applications in cancer treatment, highlighting their importance as key targets in overcoming drug resistance and enhancing the efficacy of tumor therapies.

Impact of Radiation Therapy on Serum Humanin and MOTS-c Levels in Patients with Lung or Breast Cancer

BACKGROUND

Lung and breast cancer are the most frequent causes of death from cancer globally. The objectives of this research were to evaluate the serum mitochondrial open reading frame of the 12S rRNA-c (MOTS-c) and humanin levels in lung or breast cancer patients, and investigate the impacts of radiation therapy on the circulating levels of these peptides.

METHODS

35 lung cancer patients, 34 breast cancer patients, and healthy volunteers as a control group were recruited in this prospective observatory research. Lung cancer patients with stage IIIA/IIIB were treated with paclitaxel-based chemotherapy plus radiotherapy (2 Gy per day, 30 times, 60 Gy total dose). Breast cancer stage IIA/IIB patients were treated with postoperative locoregional radiation therapy (2 Gy per day, 25 times, 50 Gy total dose). The ELISA method was used to detect serum humanin and MOTS-c levels during, before, and after radiotherapy.

RESULTS

We observed marked elevations in circulating MOTS-c, but not humanin levels in patients with lung cancer (P < 0.001). Radiation therapy led to a marked augmentation in MOTS-c levels in these patients (P < 0.001). On the other hand, there was a marked decline in humanin, but not MOTS-c, levels in breast cancer patients (P < 0.001).

CONCLUSION

Our research has shown, for the first time, that increased MOTS-c and decreased humanin levels play a role in lung cancer and breast cancer, respectively. Additionally, radiotherapy modifies MOTS-c levels in patients with lung, but not breast cancer.

Impact of Type 2 Diabetes Mellitus on the Prognosis of Non-Small Cell Lung Cancer

OBJECTIVE

Type 2 diabetes mellitus (T2DM) is the most common metabolic disease and is characterized by sustained hyperglycemia. The impact of T2DM on the survival of lung cancer patients remains controversial. The aim of this study was to investigate the associations of type 2 diabetes with lung cancer mortality.

METHODS

From January 2019 to January 2020, 228 patients with non-small cell lung cancer (NSCLC) staging earlier than IIIA were included.

RESULTS

In our study, we found that the overall survival (OS) and progression-free survival (PFS) of lung cancer patients with diabetes was longer than non-diabetes group. Diagnosed T2DM was associated with the prognosis of lung cancer after adjusting for age and covariates. The association between T2DM and OS was influenced by age, stage of cancer and cancer treatment, as well as whether taking metformin was associated with the OS of lung cancer. However, with the adjustment for age and covariates, the relation trended to lose statistical significance.

CONCLUSION

T2DM is an independent prognostic factor for patients with NSCLC staging before IIIA. The patients with both NSCLC and T2DM trended to having a longer OS, possibly due to metformin.

AXL Promotes Metformin-Induced Apoptosis Through Mediation of Autophagy by Activating ROS-AMPK-ULK1 Signaling in Human Esophageal Adenocarcinoma

AXL receptor tyrosine kinase promotes an invasive phenotype and chemotherapy resistance in esophageal adenocarcinoma (EAC). AXL has been implicated in the regulation of autophagy, but the underlying molecular mechanism remains poorly understood. Herein, we investigate the mechanistic role of AXL in autophagy as well as metformin-induced effects on the growth and survival of EAC. We demonstrate that AXL mediates autophagic flux through activation of AMPK-ULK1 signaling in a reactive oxygen species (ROS)-dependent mechanism by glucose starvation. AXL positively regulates basal cellular ROS levels without significantly affecting mitochondrial ROS production in EAC cells. Pharmacological inhibition of cellular ROS using Trolox abrogates glucose starvation-induced AMPK signaling and autophagy. We demonstrate that AXL expression is required for metformin-induced apoptosis in EAC cells in vitro. The apoptosis induction by metformin is markedly attenuated by inhibition of autophagy through genetic silencing of Beclin1 or ATG7 autophagy mediators, thereby confirming the requirement of intact autophagy for enhancing metformin-induced apoptosis in EAC cells. Our data indicate that metformin-induced autophagy displays a pro-apoptotic function in EAC cells. We show that the metformin-induced suppression of tumor growth in vivo is highly dependent on AXL expression in a tumor xenograft mouse model of EAC. We demonstrate that AXL promotes metformin-induced apoptosis through activation of autophagy in EAC. AXL may be a valuable biomarker to identify tumors that are sensitive to metformin. Therefore, AXL expression could inform the selection of patients for future clinical trials to evaluate the therapeutic efficacy of metformin in EAC.

Will We Unlock the Benefit of Metformin for Patients with Lung Cancer? Lessons from Current Evidence and New Hypotheses

Metformin has been under basic and clinical study as an oncological repurposing pharmacological agent for several years, stemming from observational studies which consistently evidenced that subjects who were treated with metformin had a reduced risk for development of cancer throughout their lives, as well as improved survival outcomes when diagnosed with neoplastic diseases. As a result, several basic science studies have attempted to dissect the relationship between metformin’s metabolic mechanism of action and antineoplastic cellular signaling pathways. Evidence in this regard was compelling enough that a myriad of randomized clinical trials was planned and conducted in order to establish the effect of metformin treatment for patients with diverse neoplasms, including lung cancer. As with most novel antineoplastic agents, early results from these studies have been mostly discouraging, though a recent analysis that incorporated body mass index may provide significant information regarding which patient subgroups might derive the most benefit from the addition of metformin to their anticancer treatment. Much in line with the current pipeline for anticancer agents, it appears that the benefit of metformin may be circumscribed to a specific patient subgroup. If so, addition of metformin to antineoplastic agents could prove one of the most cost-effective interventions proposed in the context of precision oncology. Currently published reviews mostly rely on a widely questioned mechanism of action by metformin, which fails to consider the differential effects of the drug in lean vs. obese subjects. In this review, we analyze the pre-clinical and clinical information available to date regarding the use of metformin in various subtypes of lung cancer and, further, we present evidence as to the differential metabolic effects of metformin in lean and obese subjects where, paradoxically, the obese subjects have reported more benefit with the addition of metformin treatment. The novel mechanisms of action described for this biguanide may explain the different results observed in clinical trials published in the last decade. Lastly, we present novel hypothesis regarding potential biomarkers to identify who might reap benefit from this intervention, including the role of prolyl hydroxylase domain 3 (PHD3) expression to modify metabolic phenotypes in malignant diseases.

Signal pathways and precision therapy of small-cell lung cancer

Small-cell lung cancer (SCLC) encounters up 15% of all lung cancers, and is characterized by a high rate of proliferation, a tendency for early metastasis and generally poor prognosis. Most of the patients present with distant metastatic disease at the time of clinical diagnosis, and only one-third are eligible for potentially curative treatment. Recently, investigations into the genomic make-up of SCLC show extensive chromosomal rearrangements, high mutational burden and loss-of-function mutations of several tumor suppressor genes. Although the clinical development of new treatments for SCLC has been limited in recent years, a better understanding of oncogenic driver alterations has found potential novel targets that might be suitable for therapeutic approaches. Currently, there are six types of potential treatable signaling pathways in SCLC, including signaling pathways targeting the cell cycle and DNA repair, tumor development, cell metabolism, epigenetic regulation, tumor immunity and angiogenesis. At this point, however, there is still a lack of understanding of their role in SCLC tumor biology and the promotion of cancer growth. Importantly optimizing drug targets, improving drug pharmacology, and identifying potential biomarkers are the main focus and further efforts are required to recognize patients who benefit most from novel therapies in development. This review will focus on the current learning on the signaling pathways, the status of immunotherapy, and targeted therapy in SCLC.

LKB1: Can We Target an Hidden Target? Focus on NSCLC

LKB1 (liver kinase B1) is a master regulator of several processes such as metabolism, proliferation, cell polarity and immunity. About one third of non-small cell lung cancers (NSCLCs) present LKB1 alterations, which almost invariably lead to protein loss, resulting in the absence of a potential druggable target. In addition, LKB1-null tumors are very aggressive and resistant to chemotherapy, targeted therapies and immune checkpoint inhibitors (ICIs). In this review, we report and comment strategies that exploit peculiar co-vulnerabilities to effectively treat this subgroup of NSCLCs. LKB1 loss leads to an enhanced metabolic avidity, and treatments inducing metabolic stress were successful in inhibiting tumor growth in several preclinical models. Biguanides, by compromising mitochondria and reducing systemic glucose availability, and the glutaminase inhibitor telaglenastat (CB-839), inhibiting glutamate production and reducing carbon intermediates essential for TCA cycle progression, have provided the most interesting results and entered different clinical trials enrolling also LKB1-null NSCLC patients. Nutrient deprivation has been investigated as an alternative therapeutic intervention, giving rise to interesting results exploitable to design specific dietetic regimens able to counteract cancer progression. Other strategies aimed at targeting LKB1-null NSCLCs exploit its pivotal role in modulating cell proliferation and cell invasion. Several inhibitors of LKB1 downstream proteins, such as mTOR, MEK, ERK and SRK/FAK, resulted specifically active on LKB1-mutated preclinical models and, being molecules already in clinical experimentation, could be soon proposed as a specific therapy for these patients. In particular, the rational use in combination of these inhibitors represents a very promising strategy to prevent the activation of collateral pathways and possibly avoid the potential emergence of resistance to these drugs. LKB1-null phenotype has been correlated to ICIs resistance but several studies have already proposed the mechanisms involved and potential interventions. Interestingly, emerging data highlighted that LKB1 alterations represent positive determinants to the new KRAS specific inhibitors response in KRAS co-mutated NSCLCs. In conclusion, the absence of the target did not block the development of treatments able to hit LKB1-mutated NSCLCs acting on several fronts. This will give patients a concrete chance to finally benefit from an effective therapy.

Benefits of Metformin Combined with Pemetrexed-Based Platinum Doublets as a First-Line Therapy for Advanced Lung Adenocarcinoma Patients with Diabetes

Lung cancer remains a challenge in daily practice. Chemotherapy is first considered for advanced lung adenocarcinoma bearing no active driver mutations. Maintaining drug efficacy and overcoming drug resistance are essential. This study aimed to explore the real-world use of anti-diabetic agent metformin in combination with pemetrexed-based platinum doublets in a first-line setting. We retrospectively collected data during 2004~2013 from TaiwaN's National Health Insurance Research Database to access the survival benefit of metformin combined with pemetrexed-based platinum doublets as a first-line therapy for diabetic patients with advanced lung adenocarcinoma. Demographic data and information regarding platinum reagents, diabetes medications, and metformin doses were gathered, and overall survival status regarding metformin use was analyzed. Overall survival status based on the daily dose and the calculated cumulative defined daily dose (DDD) of metformin prescribed during the first 3 months after lung cancer was diagnosed was also assessed. A total of 495 patients were enrolled with a mean age of 67 years old, and the majority of the patients were male. After adjusting for age, sex, diabetes medication, and platinum reagents used, the adjusted hazard ratio (HR) for the metformin-user group was 0.61 (95% confidence interval (CI); 0.46~0.79; p < 0.001). The metformin-user group had a survival benefit (log-rank p < 0.001). We analyzed metformin dosing during the first 3 months after lung cancer diagnosis, and for a daily dose ≥ 1500 mg, the adjusted hazard ratio (aHR) was 0.42 (95% CI; 0.27~0.65; p < 0.001). Regarding the cumulative DDD of metformin, a DDD equal to or exceeding 21 resulted in aHR of 0.48 (95% CI; 0.34~0.69; p < 0.001). In this study, we found that the combination of metformin and pemetrexed-based platinum doublets provides a robust survival benefit as a first-line therapy for diabetic patients with advanced lung adenocarcinoma. It is worth conducting a large and randomized clinical trial to further investigate the antitumor effects of metformin on advanced lung adenocarcinoma when used as a first-ling therapy, including in non-diabetic patients.

Additive Antiproliferative and Antiangiogenic Effects of Metformin and Pemetrexed in a Non-Small-Cell Lung Cancer Xenograft Model

Lung cancer is heterogeneous and challenging to cope with once it has progressed. Chemotherapy is the first step once no active driver mutation has been discovered. Non-antitumor drugs have been found to be beneficial when used as adjuvants to chemotherapy. In this study, the additive effect and mechanism of metformin combined with pemetrexed in non-small-cell lung cancer (NSCLC) cells were elucidated. Three NSCLC cell lines, A549, H1975, and HCC827, were used to analyze tumor cell proliferation, colony formation and the cell cycle in vitro when exposed to metformin alone, pemetrexed alone or their combination. We found that combination treatment in three cell lines exerted antiproliferative effects through cell cycle arrest in the S phase. An ex vivo chicken chorioallantoic membrane (CAM) assay was used to examine the antiangiogenic effect of metformin combined with pemetrexed on vascular structure formation. We further created an A549 orthotopic xenograft model with an in vivo imaging system (IVIS) and explored the associated indicators involved in the tumorigenic process. The in vitro results showed that the combination of metformin and pemetrexed exhibited an antiproliferative effect in reducing cell viability and colony formation, the downregulation of cyclin D1 and A2 and the upregulation of CDKN1B, which are involved in the G1/S phase. For antiangiogenic effects, the combination therapy inhibited the vascular structure, as proven by the CAM assay. We elucidated that combination therapy could target VEGFA and Endoglin by RT-qPCR, ELISA and histopathological findings in an A549 orthotopic NSCLC xenograft model. Our research demonstrated the additive antiproliferative and antiangiogenic effects of the combination of metformin with pemetrexed in NSCLC and could be applied to clinical lung cancer therapy.

Therapeutic potential of AMPK signaling targeting in lung cancer: Advances, challenges and future prospects

Lung cancer (LC) is a leading cause of death worldwide with high mortality and morbidity. A wide variety of risk factors are considered for LC development such as smoking, air pollution and family history. It appears that genetic and epigenetic factors are also potential players in LC development and progression. AMP-activated protein kinase (AMPK) is a signaling pathway with vital function in inducing energy balance and homeostasis. An increase in AMP:ATP and ADP:ATP ratio leads to activation of AMPK signaling by upstream mediators such as LKB1 and CamKK. Dysregulation of AMPK signaling is a common finding in different cancers, particularly LC. AMPK activation can significantly enhance LC metastasis via EMT induction. Upstream mediators such as PLAG1, IMPAD1, and TUFM can regulate AMPK-mediated metastasis. AMPK activation can promote proliferation and survival of LC cells via glycolysis induction. In suppressing LC progression, anti-tumor compounds including metformin, ginsenosides, casticin and duloxetine dually induce/inhibit AMPK signaling. This is due to double-edged sword role of AMPK signaling in LC cells. Furthermore, AMPK signaling can regulate response of LC cells to chemotherapy and radiotherapy that are discussed in the current review.

[Research Advance in Anti-lung Cancer Mechanism of Metformin]

二甲双胍作为治疗2型糖尿病的一线用药，安全性及有效性得到证实。近年来流行病学研究发现二甲双胍具有抑制肺癌细胞增殖及转移等特性，有望成为一种新的抗肺癌药物。肺癌是一种严重危害人类健康的疾病，其发病率和死亡率一直居所有恶性肿瘤之首，且预后差。近年来大量证据表明二甲双胍能降低肺癌等肿瘤的发病风险及死亡率，其机制主要包括激活单磷酸腺苷活化的蛋白激酶通路、改善高胰岛素血症及胰岛素抵抗、促进肺癌细胞凋亡、抑制相关炎症反应等。本文就二甲双胍对肺癌的研究做一综述。

Licochalcone A inhibits EGFR signalling and translationally suppresses survivin expression in human cancer cells

Dysfunction of epidermal growth factor receptor (EGFR) signalling plays a critical role in the oncogenesis of non–small‐cell lung cancer (NSCLC). Here, we reported the natural product, licochalcone A, exhibited a profound anti‐tumour efficacy through directly targeting EGFR signalling. Licochalcone A inhibited in vitro cell growth, colony formation and in vivo tumour growth of either wild‐type (WT) or activating mutation EGFR‐expressed NSCLC cells. Licochalcone A bound with L858R single‐site mutation, exon 19 deletion, L858R/T790M mutation and WT EGFR ex vivo, and impaired EGFR kinase activity both in vitro and in NSCLC cells. The in silico docking study further indicated that licochalcone A interacted with both WT and mutant EGFRs. Moreover, licochalcone A induced apoptosis and decreased survivin protein robustly in NSCLC cells. Mechanistically, we found that treatment with licochalcone A translationally suppressed survivin through inhibiting EGFR downstream kinases ERK1/2 and Akt. Depletion of the translation initiation complex by eIF4E knockdown effectively inhibited survivin expression. In contrast, knockdown of 4E‐BP1 showed the opposite effect and dramatically enhanced survivin protein level. Overall, our data indicate that targeting survivin might be an alternative strategy to sensitize EGFR‐targeted therapy.

Molecular mechanisms underlining the role of metformin as a therapeutic agent in lung cancer

BACKGROUND

Metformin, a first-line therapeutic for type 2 diabetes, has been studied for its potential use in cancer treatment following a number of epidemiological studies that have demonstrated reduced cancer incidence and mortality rates among patients treated with the drug. As yet, however, there remains significant uncertainty about the molecular mechanisms by which metformin exerts its anti-cancer effects. Herein, we summarize the evidence surrounding the anti-lung cancer effects of metformin.

CONCLUSIONS

Specifically, we explore protein targets of metformin, including AMPK, PP2A, IRF-1/YAP and HGF and we outline the proposed mechanisms of action for metformin in lung cancer, with particular attention given to apoptosis and autophagy. We also closely examine the synergistic activity of metformin with existing cancer treatment regimens, such as TKI's, platinum-based agents and immune therapeutics. In addition to considering preclinical and clinical studies, we also dissect and contextualize the limitations and inconsistencies of the current literature, especially those of epidemiological studies. Finally, we offer a potential trajectory for future research in this rapidly evolving area of basic and clinical oncology.