STAT3 contributes to cisplatin resistance, modulating EMT markers, and the mTOR signaling in lung adenocarcinoma

The role of the tumour microenvironment in lung cancer and its therapeutic implications

Lung cancer is the leading cause of cancer-related deaths globally, with tumour growth, invasion, and treatment response heavily influenced by the tumour microenvironment (TME). The TME promotes tumour progression by creating an immunosuppressive environment that hampers the body's antitumour immune response, primarily through the Nuclear Factor Kappa B (NF-κB) and Signal Transducer and Activator of Transcription 3 (STAT3) pathways. These pathways contribute to chronic inflammation, immune evasion, and angiogenesis. Targeting the TME and its signalling pathways has shown potential to enhance treatment efficacy. STAT3, a key transcription factor in lung cancer, drives tumour growth and immune suppression via the mTOR and JAK pathways. Inhibiting these pathways can block STAT3 and slow cancer progression. Promising results have been observed with mTOR inhibitors like CC-115 and Vistusertib, especially when combined with immune checkpoint inhibitors, and with JAK inhibitors such as Ruxolitinib, AZD4205, and Filgotinib. These strategies represent a promising direction for lung cancer therapy. This review explores the intricate relationship between the TME and lung cancer, focussing on novel therapeutic approaches that target immune cells, signalling molecules, and fibroblasts within the TME to improve patient outcomes.

Extracts from Allium pseudojaponicum Makino Target STAT3 Signaling Pathway to Overcome Cisplatin Resistance in Lung Cancer

Lung cancer, particularly non-small-cell lung cancer (NSCLC), remains a leading cause of cancer-related mortality, with cisplatin-based chemotherapy being a standard treatment. However, the development of chemoresistance significantly limits its efficacy, necessitating alternative therapeutic approaches. Here, we demonstrate the anticancer effects of the extracts of Allium pseudojaponicum Makino (APE), a salt-tolerant plant, in cisplatin-resistant NSCLC. Metabolite profiling using UPLC-Q-TOF-MSE identified 13 major compounds, predominantly alkaloids (71.65%) and flavonoids (8.81%), with key bioactive constituents such as lycorine (29.81%), tazettine (17.22%), and tricetin (8.19%). APE significantly inhibited cell viability in A549 and H460 cells, reducing viability to 38.6% (A549-Ctr), 37.2% (A549-CR), 28.4% (H460-Ctr), and 30.4% (H460-CR) at 40 µg/mL after 48 h. APE also suppressed colony formation by over 90% in both 2D and soft agar assays, while showing no cytotoxicity in normal human keratinocytes up to 80 µg/mL. Flow cytometry analysis revealed APE-induced G1 phase arrest, with the G1 population increasing from 50.4% to 56.6% (A549-Ctr) and 47.5% to 58.4% (A549-CR), accompanied by reduced S phase populations. This effect was associated with the downregulation of G1/S transition regulators, including cyclin D1, CDK4, cyclin E, and CDK2. Furthermore, proteomic analysis identified STAT3 signaling as a major target of APE; APE decreased phosphorylated STAT3 and c-Myc expression, and STAT3 knockdown phenocopied the effects of APE. These findings highlight the potential of APE as a natural product-based therapeutic strategy for overcoming cisplatin resistance in NSCLC.

Suppression of JAK2/STAT3 Pathway by Notoginsenoside R1 Reduces Epithelial-Mesenchymal Transition in Non-small Cell Lung Cancer

It has bene reported that a novel saponin-notoginsenoside R1 (NGR1) possesses strong anti-tumor activities. This study aimed to investigate the role and mechanism of NGR1 in non-small cell lung cancer (NSCLC). NSCLC cell viability, proliferation, migration, and invasiveness were assessed using the ex vivo assays. NSCLC xenograft mouse models were constructed to confirm the role of NGR1 in vivo. Epithelial-mesenchymal transition (EMT)-related proteins and key markers in the JAK2/STAT3 pathway were examined using immunoblotting and immunohistochemistry analyses. NGR1 treatment suppressed NSCLC cell growth ex vivo and in vivo. It also decreased the migratory and invasive capacities of NSCLC cells. Additionally, NGR1 increased E-cadherin expression and reduced N-cadherin, vimentin, and snail expression in TGF-β1-treated NSCLC cells and xenograft tumors. JAK2/STAT3 pathway was inhibited by NGR1. Moreover, a specific inhibitor of JAK2, AG490, or STAT3 silencing significantly enhanced the effects of NGR1 against the EMT process in NSCLC cells. NGR1 restrains EMT process in NSCLC by inactivating JAK2/STAT3 signaling, suggesting the potential of NGR1 in anti-NSCLC therapy.

CRISPR/Cas9 system: a novel approach to overcome chemotherapy and radiotherapy resistance in cancer

Cancer presents a global health challenge with rising incidence and mortality. Despite treatment advances in cancer therapy, radiotherapy and chemotherapy remained the most common treatments for all types of cancers. However, resistance phenotype in cancer cells leads to unsatisfactory results in the efficiency of therapeutic strategies. Therefore, researchers strive to propose effective solutions to overcome treatment failure, which requires a deep knowledge of treatment-resistant mechanisms. The progression and occurrence of tumors can be attributed to gene mutation. Over the past decade, the emergence of clustered regularly interspaced short palindromic repeats and CRISPR-associated protein 9 (CRISPR/Cas9) genome editing has revolutionized cancer research. This versatile technology enables cancer modeling, manipulation of specific DNA sequences, and genome-wide screening. CRISPR/Cas9 is an effective tool for identifying radio- and chemoresistance genes and offering potential adjunctive treatments to overcome tumor recurrence after chemo- and radiotherapy. This article aims to explain the potential of the CRISPR/Cas9 system in improving the effectiveness of chemo- and radiotherapy and ultimately overcoming treatment failure.

p53-regulated SESN1 and SESN2 regulate cell proliferation and cell death through control of STAT3

Sestrin1 and Sestrin2 (SESN1&2) are evolutionarily conserved, stress-responsive proteins that regulate cell growth and viability. The primary target of Sestrins is the mTORC1 protein kinase, an activator of anabolic processes and an autophagy inhibitor. Our previous studies showed that inactivating SESN1&2 in lung adenocarcinoma A549 cells accelerates cell proliferation and confers resistance to cell death without affecting mTORC1 activity, suggesting that SESN1&2 modulate cellular processes via mTORC1-independent mechanisms. This work describes a new mechanism through which SESN1&2 regulate cell proliferation and death by suppressing the STAT3 transcription factor. Normally activated in response to stress and inflammation, STAT3 is frequently overactivated in human cancers. This overactivation promotes the expression of pro-proliferative and anti-apoptotic genes that drive carcinogenesis. We demonstrate that SESN1&2 inactivation stimulates STAT3 by downregulating the PTPRD phosphatase, a protein responsible for STAT3 dephosphorylation. Our study demonstrates that SESN1&2 deficiency may cause STAT3 activation and facilitate carcinogenesis and drug resistance, making SESN1&2 reactivation a potential cancer treatment strategy.

Re-Sensitization of Resistant Ovarian Cancer SKOV3/CDDP Cells to Cisplatin by Curcumin Pre-Treatment

A major challenging problem facing effective ovarian cancer therapy is cisplatin resistance. Re-sensitization of cisplatin-resistant ovarian cancer cells to cisplatin (CDDP) has become a critical issue. Curcumin (CUR), the most abundant dietary polyphenolic curcuminoids derived from turmeric (Curcuma longa), has achieved previously significant anti-cancer effects against human ovarian adenocarcinoma SKOV-3/CDDP cisplatin-resistant cells by inhibition the gene expression of the antioxidant enzymes (SOD1, SOD2, GPX1, CAT and HO1), transcription factor NFE2L2 and signaling pathway (PIK3CA/AKT1/MTOR). However, the detailed mechanisms of curcumin-mediated re-sensitization to cisplatin in SKOV-3/CDDP cells still need further exploration. Here, a suggested curcumin pre-treatment therapeutic strategy has been evaluated to effectively overcome cisplatin-resistant ovarian cancer SKOV-3/CDDP and to improve our understanding of the mechanisms behind cisplatin resistance. The findings of the present study suggest that the curcumin pre-treatment significantly exhibited cytotoxic effects and inhibited the proliferation of the SKOV-3/CDDP cell line compared to the simultaneous addition of drugs. Precisely, apoptosis induced by curcumin pre-treatment in SKOV-3/CDDP cells is mediated by mitochondrial apoptotic pathway (cleaved caspases 9, 3 and cleaved PARP) activation as well as by inhibition of thioredoxin reductase (TRXR1) and mTOR/STAT3 signaling pathway. This current study could deepen our understanding of the anticancer mechanism of CUR pre-treatment, which not only facilitates the re-sensitization of ovarian cancer cells to cisplatin but may lead to the development of targeted and effective therapeutics to eradicate SKOV-3/CDDP cancer cells.

Molecular mechanisms of mTOR-mediated cisplatin response in tumor cells

Cisplatin (CDDP) is one of the main chemotherapeutic drugs that is widely used in many cancers. However, CDDP resistance is a frequent therapeutic challenge that reduces prognosis in cancer patients. Since, CDDP has noticeable side effects in normal tissues and organs, it is necessary to assess the molecular mechanisms associated with CDDP resistance to improve the therapeutic methods in cancer patients. Drug efflux, detoxifying systems, DNA repair mechanisms, and drug-induced apoptosis are involved in multidrug resistance in CDDP-resistant tumor cells. Mammalian target of rapamycin (mTOR), as a serine/threonine kinase has a pivotal role in various cellular mechanisms such as autophagy, metabolism, drug efflux, and cell proliferation. Although, mTOR is mainly activated by PI3K/AKT pathway, it can also be regulated by many other signaling pathways. PI3K/Akt/mTOR axis functions as a key modulator of drug resistance and unfavorable prognosis in different cancers. Regarding, the pivotal role of mTOR in CDDP response, in the present review we discussed the molecular mechanisms that regulate mTOR mediated CDDP response in tumor cells.

Lung cancer treatment potential and limits associated with the STAT family of transcription factors

Lung cancer is one of the mortal cancers and the leading cause of cancer-related mortality, with a cancer survival rate of fewer than 5% in developing nations. This low survival rate can be linked to things like late-stage detection, quick postoperative recurrences in patients receiving therapy, and chemoresistance developing against various lung cancer treatments. Signal transducer and activator of transcription (STAT) family of transcription factors are involved in lung cancer cell proliferation, metastasis, immunological control, and treatment resistance. By interacting with specific DNA sequences, STAT proteins trigger the production of particular genes, which in turn result in adaptive and incredibly specific biological responses. In the human genome, seven STAT proteins have been discovered (STAT1 to STAT6, including STAT5a and STAT5b). Many external signaling proteins can activate unphosphorylated STATs (uSTATs), which are found inactively in the cytoplasm. When STAT proteins are activated, they can increase the transcription of several target genes, which leads to unchecked cellular proliferation, anti-apoptotic reactions, and angiogenesis. The effects of STAT transcription factors on lung cancer are variable; some are either pro- or anti-tumorigenic, while others maintain dual, context-dependent activities. Here, we give a succinct summary of the various functions that each member of the STAT family plays in lung cancer and go into more detail about the advantages and disadvantages of pharmacologically targeting STAT proteins and their upstream activators in the context of lung cancer treatment.

Potentiation of Cisplatin Cytotoxicity in Resistant Ovarian Cancer SKOV3/Cisplatin Cells by Quercetin Pre-Treatment

Previously, we demonstrated that the overexpression of antioxidant enzymes (SOD-1, SOD-2, Gpx-1, CAT, and HO-1), transcription factor NFE2L2, and the signaling pathway (PI3K/Akt/mTOR) contribute to the cisplatin resistance of SKOV-3/CDDP ovarian cells, and treatment with quercetin (QU) alone has been shown to inhibit the expression of these genes. The aim of this study was to expand the previous data by examining the efficiency of reversing cisplatin resistance and investigating the underlying mechanism of pre-treatment with QU followed by cisplatin in the same ovarian cancer cells. The pre-incubation of SKOV-3/CDDP cells with quercetin at an optimum dose prior to treatment with cisplatin exhibited a significant cytotoxic effect. Furthermore, a long incubation with only QU for 48 h caused cell cycle arrest at the G1/S phase, while a QU pre-treatment induced sub-G1 phase cell accumulation (apoptosis) in a time-dependent manner. An in-depth study of the mechanism of the actions revealed that QU pre-treatment acted as a pro-oxidant that induced ROS production by inhibiting the thioredoxin antioxidant system Trx/TrxR. Moreover, QU pre-treatment showed activation of the mitochondrial apoptotic pathway (cleaved caspases 9, 7, and 3 and cleaved PARP) through downregulation of the signaling pathway (mTOR/STAT3) in SKOV-3/CDDP cells. This study provides further new data for the mechanism by which the QU pre-treatment re-sensitizes SKOV-3/CDDP cells to cisplatin.

The pharmacological and biological importance of EZH2 signaling in lung cancer

Up to 18% of cancer-related deaths worldwide are attributed to lung tumor and global burden of this type of cancer is ascending. Different factors are responsible for development of lung cancer such as smoking, environmental factors and genetic mutations. EZH2 is a vital protein with catalytic activity and belongs to PCR2 family. EZH2 has been implicated in regulating gene expression by binding to promoter of targets. The importance of EZH2 in lung cancer is discussed in current manuscript. Activation of EZH2 significantly elevates the proliferation rate of lung cancer. Furthermore, metastasis and associated molecular mechanisms including EMT undergo activation by EZH2 in enhancing the lung cancer progression. The response of lung cancer to therapy can be significantly diminished due to EZH2 upregulation. Since EZH2 increases tumor progression, anti-cancer agents suppressing its expression reduce malignancy. In spite of significant effort in understanding modulatory function of EZH2 on other pathways, it appears that EZH2 can be also regulated and controlled by other factors that are described in current review. Therefore, translating current findings to clinic can improve treatment and management of lung cancer patients.

Overcoming Acquired Drug Resistance to Cancer Therapies through Targeted STAT3 Inhibition

Anti-neoplastic agents for cancer treatment utilize many different mechanisms of action and, when combined, can result in potent inhibition of cancer growth. Combination therapies can result in long-term, durable remission or even cure; however, too many times, these anti-neoplastic agents lose their efficacy due to the development of acquired drug resistance (ADR). In this review, we evaluate the scientific and medical literature that elucidate STAT3-mediated mechanisms of resistance to cancer therapeutics. Herein, we have found that at least 24 different anti-neoplastic agents-standard toxic chemotherapeutic agents, targeted kinase inhibitors, anti-hormonal agents, and monoclonal antibodies-that utilize the STAT3 signaling pathway as one mechanism of developing therapeutic resistance. Targeting STAT3, in combination with existing anti-neoplastic agents, may prove to be a successful therapeutic strategy to either prevent or even overcome ADR to standard and novel cancer therapies.

Small-molecule PROTAC mediates targeted protein degradation to treat STAT3-dependent epithelial cancer

The aberrant activation of STAT3 is associated with the etiology and progression in a variety of malignant epithelial-derived tumors, including head and neck squamous cell carcinoma (HNSCC) and colorectal cancer (CRC). Due to the lack of an enzymatic catalytic site or a ligand-binding pocket, there are no small-molecule inhibitors directly targeting STAT3 that have been approved for clinical translation. Emerging proteolysis targeting chimeric (PROTAC) technology-based approach represents a potential strategy to overcome the limitations of conventional inhibitors and inhibit activation of STAT3 and downstream genes. In this study, the heterobifunctional small-molecule-based PROTACs are successfully prepared from toosendanin (TSN), with 1 portion binding to STAT3 and the other portion binding to an E3 ubiquitin ligase. The optimized lead PROTAC (TSM-1) exhibits superior selectivity, potency, and robust antitumor effects in STAT3-dependent HNSCC and CRC - especially in clinically relevant patient-derived xenografts (PDX) and patient-derived organoids (PDO). The following mechanistic investigation identifies the reduced expression of critical downstream STAT3 effectors, through which TSM-1 promotes cell cycle arrest and apoptosis in tumor cells. These findings provide the first demonstration to our knowledge of a successful PROTAC-targeting strategy in STAT3-dependent epithelial cancer.

Targeting prolyl isomerase Pin1 as a promising strategy to overcome resistance to cancer therapies

The development of tumor therapeutic resistance is one of the important reasons for the failure of antitumor therapy. Starting with multiple targets and multiple signaling pathways is helpful in understanding the mechanism of tumor resistance. The overexpression of prolyl isomerase Pin1 is highly correlated with the malignancy of cancer, since Pin1 controls many oncogenes and tumor suppressors, as well as a variety of cancer-driving signaling pathways. Strikingly, numerous studies have shown that Pin1 is directly involved in therapeutic resistance. In this review, we mainly summarize the functions and mechanisms of Pin1 in therapeutic resistance of multifarious cancers, such as breast, liver, and pancreatic carcinomas. Furtherly, from the perspective of Pin1-driven cancer signaling pathways including Raf/MEK/ERK, PI3K/Akt, Wnt/β-catenin, NF-κB, as well as Pin1 inhibitors containing juglone, epigallocatechin-3-gallate (EGCG), all-trans retinoic acid (ATRA) and arsenic trioxide (ATO), it is better to demonstrate the important potential role and mechanism of Pin1 in resistance and sensitization to cancer therapies. It will provide new therapeutic approaches for clinical reversal and prevention of tumor resistance by employing synergistic administration of Pin1 inhibitors and chemotherapeutics, implementing combination therapy of Pin1-related cancer signaling pathway inhibitors and Pin1 inhibitors, and exploiting novel Pin1-specific inhibitors.

JAK2-Mediated Phosphorylation of Stress-Induced Phosphoprotein-1 (STIP1) in Human Cells

Stress-induced phosphoprotein-1 (STIP1)—a heat shock protein (HSP)70/HSP90 adaptor protein—is commonly overexpressed in malignant cells, where it controls proliferation via multiple signaling pathways, including JAK2/STAT3. We have previously shown that STIP1 stabilizes the protein tyrosine kinase JAK2 in cancer cells via HSP90 binding. In this study, we demonstrate that STIP1 may act as a substrate for JAK2 and that phosphorylation of tyrosine residues 134 and 152 promoted STIP1 protein stability, induced its nuclear-cytoplasmic shuttling, and promoted its secretion into the extracellular space. We also found that JAK2-mediated STIP1 phosphorylation enhanced cell viability and increased resistance to cisplatin-induced cell death. Conversely, interference STIP1 with JAK2 interaction—attained either through site-directed mutagenesis or the use of cell-penetrating peptides—decreased JAK2 protein levels, ultimately leading to cell death. On analyzing human ovarian cancer specimens, JAK2 and STIP1 expression levels were found to be positively correlated with each other. Collectively, these results indicate that JAK2-mediated phosphorylation of STIP-1 is critical for sustaining the JAK2/STAT3 signaling pathway in cancer cells.

Ginsenoside Rh4 Suppressed Metastasis of Lung Adenocarcinoma via Inhibiting JAK2/STAT3 Signaling

Lung adenocarcinoma (LAC) is a common lung cancer with a high malignancy that urgently needs to be treated with effective drugs. Ginsenoside Rh4 exhibits outstanding antitumor activities. However, few studies reported its effects on growth, metastasis and molecular mechanisms in LAC. Here, Rh4 is certified to show a strong anti-LAC efficiency in vitro and in vivo. Results of flow cytometry and Western blot are obtained to exhibited that Rh4 markedly restrained cellular proliferation and colony formation by arresting the cell cycle in the G1 phase. Results from a wound healing assay and transwell assays demonstrated that Rh4 is active in the antimigration and anti-invasion of LAC. The analysis of Western blot, immunofluorescence and RT-qPCR confirmed that Rh4 reverses the epithelial–mesenchymal transition (EMT) through upregulating the gene expression of E-cadherin and downregulating that of snail, N-cadherin and vimentin. In vivo results from immunohistochemistry show consistent trends with cellular studies. Furthermore, Rh4 suppresses the Janus kinases2/signal transducer and activator of the transcription3 (JAK2/STAT3) signaling pathway stimulated by TGF-β1. Silencing the STAT3 signal or co-treating with AG490 both enhanced the EMT attenuation caused by Rh4, which revealed that Rh4 suppressed EMT via inhibiting the JAK2/STAT3 signaling pathway. These findings explore the capacity and mechanism of Rh4 on the antimetastasis of LAC, providing evidence for Rh4 to LAC therapy.