Inhibition of Hedgehog signaling sensitizes NSCLC cells to standard therapies through modulation of EMT-regulating miRNAs

MicroRNAs as Sensitizers of Tyrosine Kinase Inhibitor Resistance in Cancer: Small Molecule Partnerships

Tyrosine kinase inhibitors (TKIs) have revolutionized cancer treatments by being less toxic and improving the survival of cancer patients. The greatest challenge to their success is the resistance exhibited by cancer patients. However, the potential of microRNAs (miRNAs) for sensitizing molecules to TKIs has been well recognized, with several reports publishing promising results. Nonetheless, this therapeutic window faces challenges and several often-overlooked limitations. One of the most fundamental challenges is selecting the optimal miRNA candidates for clinical trials, as miRNAs are promiscuous and regulate hundreds of targets. In this review, we describe how miRNAs enhance sensitivity to TKIs across various types of cancer. We highlight several challenges and limitations in achieving a successful collaboration between small molecules (TKIs-miRNAs). Our focus is on proposing a workflow to select the most suitable miRNA candidate, recommending several available bioinformatics tools to develop a successful therapeutic partnership between TKIs and miRNAs. We hope that this initial proposal will provide valuable support for future research.

Folic Acid-Modified Milk Exosomes Delivering c-Kit siRNA Overcome EGFR-TKIs Resistance in Lung Cancer by Suppressing mTOR Signaling and Stemness

The EGFR-TKIs (epidermal growth factor receptor-tyrosine kinases inhibitors) offer significant benefits to lung cancer patients with sensitive EGFR mutations; however, the development of acquired resistance poses a significant challenge and leads to poor prognosis. Thus, exploring novel therapeutic strategies to overcome EGFR-TKI resistance is urgently needed. This study introduces an innovative approach utilizing folic acid-modified milk exosomes loaded with c-kit siRNA (FA-mExo-siRNA-c-kit) to target EGFR-TKI resistance in lung cancer. Initially, gefitinib-resistant lung cancer cells exhibited stemness characteristics, including an epithelial-to-mesenchymal transition phenotype and elevated ABCG2 expression, which were closely regulated by c-kit. Subsequent treatment with FA-mExo-siRNA-c-kit demonstrated effective suppression of c-kit expression and attenuation of stemness traits in vitro, reducing gefitinib resistance. In xenograft and liver metastasis models, sequential administration of FA-mExo-siRNA-c-kit and gefitinib resulted in decreased tumor growth and prolonged survival. Mechanistically, c-kit was found to regulate the AKT/mTOR/4EBP1/eIF4E axis, promoting stemness and gefitinib resistance in lung cancer cells. This study unveils a novel mechanism of EGFR-TKI resistance involving the c-kit/mTOR pathway and proposes a promising therapeutic strategy for EGFR-TKI-resistant lung cancer, particularly with liver metastasis, using FA-mExo-siRNA-c-kit, suggesting potential for improved patient outcomes and warranting further investigation.

Combination of Vismodegib and Paclitaxel Enhances Cytotoxicity via Bak-mediated Mitochondrial Damage in EGFR-Mutant Non-Small Cell Lung Cancer Cells

Half of NSCLC patients harbor epidermal growth factor receptor (EGFR) mutations, and their therapeutic responses are remarkably different from patients with wild-type EGFR (EGFR-WT) NSCLC. We previously demonstrated that the hedgehog inhibitor vismodegib (Vis) potentiates paclitaxel (PTX)-induced cytotoxicity via suppression of Bax phosphorylation, which promotes accumulation of mitochondrial damage and apoptosis in EGFR-WT NSCLC cells. In this study, we further delineated the anticancer activity and underlying mechanisms of this combination treatment in EGFR-mutant NSCLC cells. MTS/PMS activity and trypan blue exclusion assays were used to assess cell viability. Apoptosis was monitored by chromosome condensation, annexin V staining, and cleavage of PARP and caspase-3. Western blots were conducted to track proteins of interest after treatment. Reactive oxygen species (ROS) level was monitored by 2',7'-dichlorodihydrofluorescein diacetate. Mitochondrial status was analyzed by tetramethylrhodamine, ethyl ester. Hedgehog signaling was induced by PTX, which rendered H1975 and PC9 cells insensitive to PTX-induced mitochondrial apoptosis via suppression of Bak. However, Vis enhanced PTX-induced Bak activation, leading to mitochondrial damage, ROS accumulation, and subsequent apoptosis. Our findings suggest that the combination of Vis and PTX could be a potential therapeutic strategy to increase PTX sensitivity of EGFR-mutant NSCLC.

Hedgehog ligand and receptor cooperatively regulate EGFR stability and activity in non-small cell lung cancer

PURPOSE

The hyperactivation of epidermal growth factor receptor (EGFR) plays a crucial role in non-small cell lung cancer (NSCLC). Hedgehog (Hh) signaling has been implicated in the tumorigenesis and progression of various cancers, however, its function in NSCLC cells remains controversial. Herein, we present a novel finding that challenges the current understanding of Hh signaling in tumor growth.

METHODS

Expression of Hh ligands and receptor were assessed using TCGA datasets, immunoblotting and immunohistochemical. Biological function of Hh ligands and receptor in NSCLC were tested using colony formation, cell count kit-8 (CCK-8) and xenograft assays. Biochemical effect of Hh ligands and receptor on regulating EGFR stability and activity were checked via immunoblotting.

RESULTS

Expression of Hh ligands and receptor was suppressed in NSCLC tissues, and the lower expression levels of these genes were associated with poor prognosis. Ptch1 binds to EGFR and facilitates its poly-ubiquitylation and degradation independent of downstream transcriptional signaling. Moreover, Hh ligands cooperate with Ptch1 to regulate the protein stability and activity of EGFR. This unique mechanism leads to a suppressive effect on NSCLC tumor growth.

CONCLUSION

Non-canonical Hh signaling pathway, involving cooperation between Hh ligands and their receptor Ptch1, facilitates the degradation of EGFR and attenuates its activity in NSCLC. These findings provide novel insights into the regulation of EGFR protein stability and activity, offer new diagnostic indicators for molecular typing of NSCLC and identify potential targets for targeted therapy of this challenging disease.

Evaluation of Clinically Significant miRNAs Level by Machine Learning Approaches Utilizing Total Transcriptome Data

Analysis of the mechanisms underlying the occurrence and progression of cancer represents a key objective in contemporary clinical bioinformatics and molecular biology. Utilizing omics data, particularly transcriptomes, enables a detailed characterization of expression patterns and post-transcriptional regulation across various RNA types relative to the entire transcriptome. Here, we assembled a dataset comprising transcriptomic data from approximately 16 000 patients encompassing over 160 types of cancer. We employed state-of-the-art gradient boosting algorithms to discern intricate correlations in the expression levels of four clinically significant microRNAs, specifically, hsa-mir-21, hsa-let-7a-1, hsa-let-7b, and hsa-let-7i, with the expression levels of the remaining 60 660 unique RNAs. Our analysis revealed a dependence of the expression levels of the studied microRNAs on the concentrations of several small nucleolar RNAs and regulatory long noncoding RNAs. Notably, the roles of these RNAs in the development of specific cancer types had been previously established through experimental evidence. Subsequent evaluation of the created database will facilitate the identification of a broader spectrum of overarching dependencies related to changes in the expression levels of various RNA classes in diverse cancers. In future, it will make possible to discover unique alterations specific to certain types of malignant transformations.

Vismodegib Potentiates Marine Antimicrobial Peptide Tilapia Piscidin 4-Induced Cytotoxicity in Human Non-Small Cell Lung Cancer Cells

Non-small cell lung cancer (NSCLC) is a common cancer with several accepted treatments, such as chemotherapy, epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors, and immune checkpoint inhibitors. Nevertheless, NSCLC cells often become insensitive to these treatments, and therapeutic resistance is a major reason NSCLC still has a high mortality rate. The induction of therapeutic resistance in NSCLC often involves hedgehog, and suppression of hedgehog can increase NSCLC cell sensitivity to several conventional therapies. In our previous work, we demonstrated that the marine antimicrobial peptide tilapia piscidin 4 (TP4) exhibits potent anti-NSCLC activity in both EGFR-WT and EGFR-mutant NSCLC cells. Here, we sought to further explore whether hedgehog might influence the sensitivity of NSCLC cells to TP4. Our results showed that hedgehog was activated by TP4 in both WT and EGFR-mutant NSCLC cells and that pharmacological inhibition of hedgehog by vismodegib, a Food and Drug Administration-approved hedgehog inhibitor, potentiated TP4-induced cytotoxicity. Mechanistically, vismodegib acted by enhancing TP4-mediated increases in mitochondrial membrane potential and intracellular reactive oxygen species (ROS). MitoTempo, a specific mitochondrial ROS scavenger, abolished vismodegib/TP4 cytotoxicity. The combination of vismodegib with TP4 also reduced the levels of the antioxidant proteins catalase and superoxide dismutase, and it diminished the levels of chemoresistance-related proteins, Bcl-2 and p21. Thus, we conclude that hedgehog regulates the cytotoxic sensitivity of NSCLC cells to TP4 by protecting against mitochondrial dysfunction and suppressing oxidative stress. These findings suggest that combined treatment of vismodegib and TP4 may be a promising therapeutic strategy for NSCLC.

Cancer stem cells: a target for overcoming therapeutic resistance and relapse

Cancer stem cells (CSCs) are a small subset of cells in cancers that are thought to initiate tumorous transformation and promote metastasis, recurrence, and resistance to treatment. Growing evidence has revealed the existence of CSCs in various types of cancers and suggested that CSCs differentiate into diverse lineage cells that contribute to tumor progression. We may be able to overcome the limitations of cancer treatment with a comprehensive understanding of the biological features and mechanisms underlying therapeutic resistance in CSCs. This review provides an overview of the properties, biomarkers, and mechanisms of resistance shown by CSCs. Recent findings on metabolic features, especially fatty acid metabolism and ferroptosis in CSCs, are highlighted, along with promising targeting strategies. Targeting CSCs is a potential treatment plan to conquer cancer and prevent resistance and relapse in cancer treatment.

Cancer stem cell-derived exosome-induced metastatic cancer: An orchestra within the tumor microenvironment

Although the mechanisms as well as pathways associated with cancer stem cell (CSC) maintenance, expansion, and tumorigenicity have been extensively studied and the role of tumor cell (TC)-derived exosomes in this process is well understood, there is a paucity of research focusing specifically on the functional mechanisms of CSC-derived exosomes (CSC-Exo)/-exosomal-ncRNAs and their impact on malignancy. This shortcoming needs to be addressed, given that these vesicular and molecular components of CSCs could have a great impact on the cancer initiation, progression, and recurrence through their interaction with other key tumor microenvironment (TME) components, such as MSCs/MSC-Exo and CAFs/CAF-Exo. In particular, understanding CSCs/CSC-Exo and its crosstalk with MSCs/MSC-Exo or CAFs/CAF-Exo that are associated with the proliferation, migration, differentiation, angiogenesis, and metastasis through an enhanced process of self-renewal, chemotherapy as well as radiotherapy resistance may aid cancer treatment. This review contributes to this endeavor by summarizing the characteristic features and functional mechanisms of CSC-Exo/MSC-Exo/CAF-Exo and their mutual impact on cancer progression and therapy resistance.

Hedgehog/GLI and gastric cancer: Research progress and current status

Hedgehog/GLI (Hh/GLI) is an important signaling pathway. It has been confirmed in various cancer studies that mutated or dysregulated Hh signals may be the behavioral phenotype of tumors, leading to the occurrence of various cancers. The abnormally activated Hh pathway endows tumor cells with a tendency to occur, proliferate, and migrate. In recent years, studies have found that the Hh signaling pathway induces gastric cancer (GC) invasion and epithelial mesenchymal transition. This article reviews the research progress and current status of Hh/GLI related to GC. Unveiling the new veil of GC occurrence will open a new approach for targeted therapy of this malignancy.

The role of LIN28B in tumor progression and metastasis in solid tumor entities

LIN28B is an RNA-binding protein that targets a broad range of microRNAs and modulates their maturation and activity. Under normal conditions, LIN28B is exclusively expressed in embryogenic stem cells, blocking differentiation and promoting proliferation. In addition, it can play a role in epithelial-to-mesenchymal transition by repressing the biogenesis of let-7 microRNAs. In malignancies, LIN28B is frequently overexpressed, which is associated with increased tumor aggressiveness and metastatic properties. In this review, we discuss the molecular mechanisms of LIN28B in promoting tumor progression and metastasis in solid tumor entities and its potential use as a clinical therapeutic target and biomarker.

Mechanotransduction in tumor dynamics modeling

Mechanotherapy is a groundbreaking approach to impact carcinogenesis. Cells sense and respond to mechanical stimuli, translating them into biochemical signals in a process known as mechanotransduction. The impact of stress on tumor growth has been studied in the last three decades, and many papers highlight the role of mechanics as a critical self-inducer of tumor fate at the in vitro and in vivo biological levels. Meanwhile, mathematical models attempt to determine laws to reproduce tumor dynamics. This review discusses biological mechanotransduction mechanisms and mathematical-biomechanical models together. The aim is to provide a common framework for the different approaches that have emerged in the literature from the perspective of tumor avascularity and to provide insight into emerging mechanotherapies that have attracted interest in recent years.

A perspective to weaponize microRNAs against lung cancer

microRNAs are regulatory RNAs that silence specific mRNA by binding to it, inducing translational repression. Over the recent decades since the discovery of RNA interference, the field of microRNA therapeutics has expanded tremendously. The role of miRNAs in disease development has attracted researchers to investigate their potential in therapeutics. In lung cancer, multiple miRNAs are deregulated, and their involvement is observed in cell proliferation, immunomodulation, angiogenesis, and epithelial-mesenchymal transition. Thus, synthetic oligonucleotides are developed to downregulate the overexpressed miRNA or to upregulate the repressed miRNA. However, their clinical efficiency is limited due to the requirement for an effective delivery strategy. Advances in the current understanding of nanotechnology, biomaterial science, and disease molecular pathology have increased the chances of overcoming the limitations of miRNA-based therapy. This review enlists downregulated and upregulated miRNAs in lung cancer. This review also highlights the major contributions to miRNA-based therapeutics for lung cancer and strategies to overcome endosomal barriers. It also attempts to understand the nuances between current advancements in delivery methods, advantages, disadvantages, and practical issues for the large-scale development of miRNA-based therapeutics.

Emerging role of non-coding RNAs in resistance to platinum-based anti-cancer agents in lung cancer

Platinum-based drugs are the first line of therapeutics against many cancers, including lung cancer. Lung cancer is one of the leading causes of cancer-related death worldwide. Platinum-based agents target DNA and prevent replication, and transcription, leading to the inhibition of cell proliferation followed by cellular apoptosis. About twenty-three platinum-based drugs are under different stages of clinical trials, among cisplatin, carboplatin, and oxaliplatin are widely used for the treatment of various cancers. Among them, cisplatin is the most commonly used drug for cancer therapy, which binds with RNA, and hinders the cellular RNA process. However, long-term use of platinum-based drugs can cause different side effects and has been shown to develop chemoresistance, leading to poor clinical outcomes. Chemoresistance became an important challenge for cancer treatment. Platinum-based chemoresistance occurs due to the influence of intrinsic factors such as overexpression of multidrug resistance proteins, advancement of DNA repair mechanism, degradation, and deactivation of intracellular thiols. Recently, epigenetic modifications, especially non-coding RNAs (ncRNAs) mediated gene regulation, grasp the attention for reversing the sensitivity of platinum-based drugs due to their reversible nature without altering genome sequence. ncRNAs can also modulate the intrinsic and non-intrinsic mechanisms of resistance in lung cancer cells. Therefore, targeting ncRNAs could be an effective approach for developing novel therapeutics to overcome lung cancer chemoresistance. The current review article has discussed the role of ncRNA in chemoresistance and its underlying molecular mechanisms in human lung cancer.

Cancer Stem Cells and Their Therapeutic Usage

Cancer stem cells (CSC) have unique characteristics which include self-renewal, multi-directional differentiation capacity, quiescence/dormancy, and tumor-forming capability. These characteristics are referred to as the "stemness" properties. Tumor microenvironment contributes to CSC survival, function, and remaining them in an undifferentiated state. CSCs can form malignant tumors with heterogeneous phenotypes mediated by the tumor microenvironment. Therefore, the crosstalk between CSCs and tumor microenvironment can modulate tumor heterogeneity. CSCs play a crucial role in several biological processes, epithelial-mesenchymal transition (EMT), autophagy, and cellular stress response. In this chapter, we focused characteristics of cancer stem cells, reprogramming strategies cells into CSCs, and then we highlighted the contribution of CSCs to therapy resistance and cancer relapse and their potential of therapeutic targeting of CSCs.

Hedgehog pathway and its inhibitors in chronic obstructive pulmonary disease (COPD)

COPD affects millions of people and is now ranked as the third leading cause of death worldwide. This largely untreatable chronic airway disease results in irreversible destruction of lung architecture. The small lung hypothesis is now supported by epidemiological, physiological and clinical studies. Accordingly, the early and severe COPD phenotype carries the most dreadful prognosis and finds its roots during lung growth. Pathophysiological mechanisms remain poorly understood and implicate individual susceptibility (genetics), a large part of environmental factors (viral infections, tobacco consumption, air pollution) and the combined effects of those triggers on gene expression. Genetic susceptibility is most likely involved as the disease is severe and starts early in life. The latter observation led to the identification of Mendelian inheritance via disease-causing variants of SERPINA1 - known as the basis for alpha-1 anti-trypsin deficiency, and TERT. In the last two decades multiple genome wide association studies (GWAS) identified many single nucleotide polymorphisms (SNPs) associated with COPD. High significance SNPs are located in 4q31 near HHIP which encodes an evolutionarily highly conserved physiological inhibitor of the Hedgehog signaling pathway (HH). HHIP is critical to several in utero developmental lung processes. It is also implicated in homeostasis, injury response, epithelial-mesenchymal transition and tumor resistance to apoptosis. A few studies have reported decreased HHIP RNA and protein levels in human adult COPD lungs. HHIP^+/- murine models led to emphysema. HH pathway inhibitors, such as vismodegib and sonidegib, are already validated in oncology, whereas other drugs have evidenced in vitro effects. Targeting the Hedgehog pathway could lead to a new therapeutic avenue in COPD. In this review, we focused on the early and severe COPD phenotype and the small lung hypothesis by exploring genetic susceptibility traits that are potentially treatable, thus summarizing promising therapeutics for the future.

Naringin’s Prooxidant Effect on Tumor Cells: Copper’s Role and Therapeutic Implications

Plant-derived polyphenolic chemicals are important components of human nutrition and have been found to have chemotherapeutic effects against a variety of cancers. Several studies in animal models have proven polyphenols’ potential to promote apoptosis and tumor regression. However, the method by which polyphenols show their anticancer effects on malignant cells is not well understood. It is generally known that cellular copper rises within malignant cells and in the serum of cancer patients. In this communication, investigations reveal that naringin (a polyphenol found in citrus fruits) can strongly suppress cell proliferation and trigger apoptosis in various cancer cell lines in the presence of copper ions. The cuprous chelator neocuproine, which confirms copper-mediated DNA damage, prevents such cell death to a large extent. The studies further show that the cellular copper transporters CTR1 and ATP7A have a role in the survival dynamics of malignant cells after naringin exposure. The findings emphasize the crucial function of copper dynamics and mobilization in cancer cells and pave the path for a better understanding of polyphenols as nutraceutical supplements for cancer prevention and treatment.

Curcumin and Its Derivatives Induce Apoptosis in Human Cancer Cells by Mobilizing and Redox Cycling Genomic Copper Ions

Turmeric spice contains curcuminoids, which are polyphenolic compounds found in the Curcuma longa plant’s rhizome. This class of molecules includes curcumin, demethoxycurcumin, and bisdemethoxycurcumin. Using prostate cancer cell lines PC3, LNCaP, DU145, and C42B, we show that curcuminoids inhibit cell proliferation (measured by MTT assay) and induce apoptosis-like cell death (measured by DNA/histone ELISA). A copper chelator (neocuproine) and reactive oxygen species scavengers (thiourea for hydroxyl radical, superoxide dismutase for superoxide anion, and catalase for hydrogen peroxide) significantly inhibit this reaction, thus demonstrating that intracellular copper reacts with curcuminoids in cancer cells to cause DNA damage via ROS generation. We further show that copper-supplemented media sensitize normal breast epithelial cells (MCF-10A) to curcumin-mediated growth inhibition, as determined by decreased cell proliferation. Copper supplementation results in increased expression of copper transporters CTR1 and ATP7A in MCF-10A cells, which is attenuated by the addition of curcumin in the medium. We propose that the copper-mediated, ROS-induced mechanism of selective cell death of cancer cells may in part explain the anticancer effects of curcuminoids.

Cancer stem cell plasticity and its implications in the development of new clinical approaches for oral squamous cell carcinoma

Oral squamous cell carcinoma (SCC) represents a major worldwide disease burden, with high rates of recurrence and metastatic spread following existing treatment methods. Populations of treatment resistant cancer stem cells (CSCs) are well characterised in oral SCC. These populations of CSCs engage the cellular programme known as epithelial mesenchymal transition (EMT) to enhance metastatic spread and therapeutic resistance. EMT is characterised by specific morphological changes and the expression of certain cell surface markers that represent a transition from an epithelial phenotype to a mesenchymal phenotype. This process is regulated by several cellular pathways that interact both horizontally and hierarchically. The cellular changes in EMT occur along a spectrum, with sub-populations of cells displaying both epithelial and mesenchymal features. The unique features of these CSCs in terms of their EMT state, cell surface markers and metabolism may offer new druggable targets. In addition, these features could be used to identify more aggressive disease states and the opportunity to personalise therapy depending on the presence of certain CSC sub-populations.

Lin28 Regulates Cancer Cell Stemness for Tumour Progression

Tumours develop therapy resistance through complex mechanisms, one of which is that cancer stem cell (CSC) populations within the tumours present self-renewable capability and phenotypical plasticity to endure therapy-induced stress conditions and allow tumour progression to the therapy-resistant state. Developing therapeutic strategies to cope with CSCs requires a thorough understanding of the critical drivers and molecular mechanisms underlying the aforementioned processes. One such hub regulator of stemness is Lin28, an RNA-binding protein. Lin28 blocks the synthesis of let-7, a tumour-suppressor microRNA, and acts as a global regulator of cell differentiation and proliferation. Lin28also targets messenger RNAs and regulates protein translation. In this review, we explain the role of the Lin28/let-7 axis in establishing stemness, epithelial-to-mesenchymal transition, and glucose metabolism reprogramming. We also highlight the role of Lin28 in therapy-resistant prostate cancer progression and discuss the emergence of Lin28-targeted therapeutics and screening methods.

Current Landscape of Therapeutic Resistance in Lung Cancer and Promising Strategies to Overcome Resistance

Lung cancer is one of the leading causes of cancer-related deaths worldwide with a 5-year survival rate of less than 18%. Current treatment modalities include surgery, chemotherapy, radiation therapy, targeted therapy, and immunotherapy. Despite advances in therapeutic options, resistance to therapy remains a major obstacle to the effectiveness of long-term treatment, eventually leading to therapeutic insensitivity, poor progression-free survival, and disease relapse. Resistance mechanisms stem from genetic mutations and/or epigenetic changes, unregulated drug efflux, tumor hypoxia, alterations in the tumor microenvironment, and several other cellular and molecular alterations. A better understanding of these mechanisms is crucial for targeting factors involved in therapeutic resistance, establishing novel antitumor targets, and developing therapeutic strategies to resensitize cancer cells towards treatment. In this review, we summarize diverse mechanisms driving resistance to chemotherapy, radiotherapy, targeted therapy, and immunotherapy, and promising strategies to help overcome this therapeutic resistance.

Pomegranate juice anthocyanidins induce cell death in human cancer cells by mobilizing intracellular copper ions and producing reactive oxygen species

Anthocyanidins are the most abundant polyphenols in pomegranate juice. This class of molecules includes Delphinidin (Del), Cyanidin (Cya), and Pelargonidin (Pel). Using prostate, breast and pancreatic cancer cell lines PC3, MDA-MB-231, BxPC-3 and MiaPaCa-2, we show that anthocyanidins inhibit cell proliferation (measured by MTT assay) and induce apoptosis like cell death (measured by DNA/Histone ELISA). Copper chelator neocuproine and reactive oxygen species scavengers (thiourea for hydroxyl radical and superoxide dismutase for superoxide anion) significantly inhibit this reaction thus demonstrating that intracellular copper reacts with anthocyanidins in cancer cells to cause DNA damage via ROS generation. We further show that copper-supplemented media sensitizes normal breast epithelial cells (MCF-10A) to Del-mediated growth inhibition as determined by decreased cell proliferation. Copper supplementation results in increased expression of copper transporters Ctr1 and ATP7A in MCF-10A cells, which is attenuated by the addition of Del in the medium. We propose that the copper mediated, ROS-induced mechanism of selective cell death of cancer cells may in part explain the anticancer effects of anthocyanidins.

Identification of solamargine as a cisplatin sensitizer through phenotypical screening in cisplatin-resistant NSCLC organoids

Although Cisplatin (DDP) is a widely used first-line chemotherapy medication, DDP resistance is one of the main causes of treatment failure in advanced lung cancer. Therefore, it is urgent to identify DDP sensitizers and investigate the underlying molecular mechanisms. Here we utilized DDP-resistant organoids established from tumor biopsies of patients with relapsed lung cancers. In this study, we identified Solamargine as a potential DDP sensitizer through screening a natural product library. Mechanically, Solamargine induced G0/G1-phase arrest and apoptosis in DDP-resistant lung cancer cell lines. Gene expression analysis and KEGG pathway analysis indicated that the hedgehog pathway was suppressed by Solamargine. Moreover, Gli responsive element (GRE) reporter gene assay and BODIPY-cyclopamine binding assay showed that Solamargine inhibited the hedgehog pathway via direct binding to SMO protein. Interestingly, Solamargine and DDP showed a synergetic effect in inhibiting DDP-resistant lung cancer cell lines. Taken together, our work herein revealed Solamargine as a hedgehog pathway inhibitor and DDP-sensitizer, which might provide a new direction for further treatment of advanced DDP-resistant lung cancer patients.

Epigenetic underpinnings of inflammation: Connecting the dots between pulmonary diseases, lung cancer and COVID-19

Inflammation is an essential component of several respiratory diseases, such as chronic obstructive pulmonary disease (COPD), asthma and acute respiratory distress syndrome (ARDS). It is central to lung cancer, the leading cancer in terms of associated mortality that has affected millions of individuals worldwide. Inflammation and pulmonary manifestations are also the major causes of COVID-19 related deaths. Acute hyperinflammation plays an important role in the COVID-19 disease progression and severity, and development of protective immunity against the virus is greatly sought. Further, the severity of COVID-19 is greatly enhanced in lung cancer patients, probably due to the genes such as ACE2, TMPRSS2, PAI-1 and furin that are commonly involved in cancer progression as well as SAR-CoV-2 infection. The importance of inflammation in pulmonary manifestations, cancer and COVID-19 calls for a closer look at the underlying processes, particularly the associated increase in IL-6 and other cytokines, the dysregulation of immune cells and the coagulation pathway. Towards this end, several reports have identified epigenetic regulation of inflammation at different levels. Expression of several key inflammation-related cytokines, chemokines and other genes is affected by methylation and acetylation while non-coding RNAs, including microRNAs as well as long non-coding RNAs, also affect the overall inflammatory responses. Select miRNAs can regulate inflammation in COVID-19 infection, lung cancer as well as other inflammatory lung diseases, and can serve as epigenetic links that can be therapeutically targeted. Furthermore, epigenetic changes also mediate the environmental factors-induced inflammation. Therefore, a better understanding of epigenetic regulation of inflammation can potentially help develop novel strategies to prevent, diagnose and treat chronic pulmonary diseases, lung cancer and COVID-19.

MiRNAs in Lung Cancer: Diagnostic, Prognostic, and Therapeutic Potential

Lung cancer is the dominant emerging factor in cancer-related mortality around the globe. Therapeutic interventions for lung cancer are not up to par, mainly due to reoccurrence/relapse, chemoresistance, and late diagnosis. People are currently interested in miRNAs, which are small double-stranded (20–24 ribonucleotides) structures that regulate molecular targets (tumor suppressors, oncogenes) involved in tumorigeneses such as cell proliferation, apoptosis, metastasis, and angiogenesis via post-transcriptional regulation of mRNA. Many studies suggest the emerging role of miRNAs in lung cancer diagnostics, prognostics, and therapeutics. Therefore, it is necessary to intensely explore the miRNOME expression of lung tumors and the development of anti-cancer strategies. The current review focuses on the therapeutic, diagnostic, and prognostic potential of numerous miRNAs in lung cancer.

Exosome-Mediated Response to Cancer Therapy: Modulation of Epigenetic Machinery

Exosomes, the extracellular vesicles produced in the endosomal compartments, facilitate the transportation of proteins as well as nucleic acids. Epigenetic modifications are now considered important for fine-tuning the response of cancer cells to various therapies, and the acquired resistance against targeted therapies often involves dysregulated epigenetic modifications. Depending on the constitution of their cargo, exosomes can affect several epigenetic events, thus impacting post-transcriptional regulations. Thus, a role of exosomes as facilitators of epigenetic modifications has come under increased scrutiny in recent years. Exosomes can deliver methyltransferases to recipient cells and, more importantly, non-coding RNAs, particularly microRNAs (miRNAs), represent an important exosome cargo that can affect the expression of several oncogenes and tumor suppressors, with a resulting impact on cancer therapy resistance. Exosomes often harbor other non-coding RNAs, such as long non-coding RNAs and circular RNAs that support resistance. The exosome-mediated transfer of all this cargo between cancer cells and their surrounding cells, especially tumor-associated macrophages and cancer-associated fibroblasts, has a profound effect on the sensitivity of cancer cells to several chemotherapeutics. This review focuses on the exosome-induced modulation of epigenetic events with resulting impact on sensitivity of cancer cells to various therapies, such as, tamoxifen, cisplatin, gemcitabine and tyrosine kinase inhibitors. A better understanding of the mechanisms by which exosomes can modulate response to therapy in cancer cells is critical for the development of novel therapeutic strategies to target cancer drug resistance.

Potential of the miR-200 Family as a Target for Developing Anti-Cancer Therapeutics

MicroRNAs (miRNAs) are small non-coding RNAs (18–24 nucleotides) that play significant roles in cell proliferation, development, invasion, cancer development, cancer progression, and anti-cancer drug resistance. miRNAs target multiple genes and play diverse roles. miRNAs can bind to the 3′UTR of target genes and inhibit translation or promote the degradation of target genes. miR-200 family miRNAs mostly act as tumor suppressors and are commonly decreased in cancer. The miR-200 family has been reported as a valuable diagnostic and prognostic marker. This review discusses the clinical value of the miR-200 family, focusing on the role of the miR-200 family in the development of cancer and anti-cancer drug resistance. This review also provides an overview of the factors that regulate the expression of the miR-200 family, targets of miR-200 family miRNAs, and the mechanism of anti-cancer drug resistance regulated by the miR-200 family.

Noncoding RNAs related to the hedgehog pathway in cancer: clinical implications and future perspectives

Cancer is a type of malignant affliction threatening human health worldwide; however, the molecular mechanism of cancer pathogenesis remains to be elusive. The oncogenic hedgehog (Hh) pathway is a highly evolutionarily conserved signaling pathway in which the hedgehog-Patched complex is internalized to cellular lysosomes for degradation, resulting in the release of Smoothened inhibition and producing downstream intracellular signals. Noncoding RNAs (ncRNAs) with diversified regulatory functions have the potency of controlling cellular processes. Compelling evidence reveals that Hh pathway, ncRNAs, or their crosstalk play complicated roles in the initiation, metastasis, apoptosis and drug resistance of cancer, allowing ncRNAs related to the Hh pathway to serve as clinical biomarkers for targeted cancer therapy. In this review, we attempt to depict the multiple patterns of ncRNAs in the progression of malignant tumors via interactions with the Hh crucial elements in order to better understand the complex regulatory mechanism, and focus on Hh associated ncRNA therapeutics aimed at boosting their application in the clinical setting.

Mechanisms of cancer stem cells drug resistance and the pivotal role of HMGA2

Nowadays, the focus of researchers is on perceiving the heterogeneity observed in a tumor. The researchers studied the role of a specific subset of cancer cells with high resistance to traditional treatments, recurrence, and unregulated metastasis. This small population of tumor cells that have stem-cell-like specifications was named Cancer Stem Cells (CSCs). The unique features that distinguish this type of cancer cell are self-renewing, generating clones of the tumor, plasticity, recurrence, and resistance to therapies. There are various mechanisms that contribute to the drug resistance of CSCs, such as CSCs markers, Epithelial mesenchymal transition, hypoxia, other cells, inflammation, and signaling pathways. Recent investigations have revealed the primary role of HMGA2 in the development and invasion of cancer cells. Importantly, HMGA2 also plays a key role in resistance to treatment through their function in the drug resistance mechanisms of CSCs and challenge it. Therefore, a deep understanding of this issue can provide a clearer perspective for researchers in the face of this problem.

Bisdemethoxycurcumin sensitizes the response of cisplatin resistant non-small cell lung carcinoma cell lines by activating apoptosis and autophagy

Lung cancer belongs to the most frequent and deadliest cancer types worldwide, non-small cell lung carcinoma (NSCLC) being the most frequent type. Development of chemoresistance in NSCLC patients is common and responsible for bad outcome. Curcuminoids are naturally occurring substances with prominent cytotoxic effects in different cancer cells. Here we analyzed influence of bisdemethoxycurcumin (BDMC) on phenotype and molecular mechanisms in cisplatin-sensitive NSCLC cell lines (A549 and H460) and their cisplatin-resistant counterparts. NSCLC cell lines were exposed to BDMC and analyzed by cell viability, proliferation, and motility assays, as well as fluorescence-activated cell sorting. Immunoblotting was assessed to detect apoptosis and autophagy. Colony-formation assay and multicellular tumor spheroid model were used to investigate the effects of BDMC. Expression levels of different Hedgehog-pathway genes were determined by RT-qPCR analysis. We identified substantial cytotoxic effects of BDMC on NSCLC cells in general and on cisplatin-resistant NSCLC cells in special. BDMC markedly decreased the cell viability by inducing apoptosis and autophagy in a cell-type specific manner. BDMC emphasized cisplatin-induced cell death and inhibited cell cycle progression of cisplatin-resistant NSCLC cells. Scratch-closure, colony formation, and multicellular spheroid growth in cisplatin-resistant NSCLC cell lines were inhibited by BDMC. Expression profile analyses of different Hedgehog-pathway regulatory genes showed that Gli1, the mean transcriptional regulator of this pathway, was markedly decreased upon the BDMC treatment, this decrement being most prominent in cisplatin-resistant cells. Our data identified BDMC as a potent substance that may be suitable for combined cisplatin-based therapy in cisplatin-resistant subpopulation of NSCLC patients.

Structure of Some Green Tea Catechins and the Availability of Intracellular Copper Influence Their Ability to Cause Selective Oxidative DNA Damage in Malignant Cells

The possible roles of elevated endogenous copper levels in malignant cells are becoming increasingly understood at a greater depth. Our laboratory has previously demonstrated that tea catechins have the ability to mobilize endogenous copper and undergo a Fenton-like reaction that can selectively damage cancer cells. In this communication, by using a diverse panel of malignant cell lines, we demonstrate that the ability of the catechin family [(−)-epigallocatechin-3-gallate (EGCG), (−)-epigallocatechin (EGC), (−)-epicatechin (EC), and (+)-catechin (C)] to induce apoptosis is dependent on their structure. We further confirm that reactive oxygen species (ROS) are the terminal effectors causing copper-mediated DNA damage. Our studies demonstrate the role of cellular copper transporters CTR1 and ATP7A in the survival dynamics of malignant cells post-EGCG exposure. The results, when considered together with our previous studies, highlight the critical role that copper dynamics and mobilization plays in cancer cells and paves the way for a better understanding of catechins as nutraceutical supplements for malignancies.

MicroRNAs as the critical regulators of tyrosine kinase inhibitors resistance in lung tumor cells

Lung cancer is the second most common and the leading cause of cancer related deaths globally. Tyrosine Kinase Inhibitors (TKIs) are among the common therapeutic strategies in lung cancer patients, however the treatment process fails in a wide range of patients due to TKIs resistance. Given that the use of anti-cancer drugs can always have side effects on normal tissues, predicting the TKI responses can provide an efficient therapeutic strategy. Therefore, it is required to clarify the molecular mechanisms of TKIs resistance in lung cancer patients. MicroRNAs (miRNAs) are involved in regulation of various pathophysiological cellular processes. In the present review, we discussed the miRNAs that have been associated with TKIs responses in lung cancer. MiRNAs mainly exert their role on TKIs response through regulation of Tyrosine Kinase Receptors (TKRs) and down-stream signaling pathways. This review paves the way for introducing a panel of miRNAs for the prediction of TKIs responses in lung cancer patients.

The Potential for Natural Products to Overcome Cancer Drug Resistance by Modulation of Epithelial-Mesenchymal Transition

The acquisition of resistance and ultimately disease relapse after initial response to chemotherapy put obstacles in the way of cancer therapy. Epithelial-mesenchymal transition (EMT) is a biologic process that epithelial cells alter to mesenchymal cells and acquire fibroblast-like properties. EMT plays a significant role in cancer metastasis, motility, and survival. Recently, emerging evidence suggested that EMT pathways are very important in making drug-resistant involved in cancer. Natural products are gradually emerging as a valuable source of safe and effective anticancer compounds. Natural products could interfere with the different processes implicated in cancer drug resistance by reversing the EMT process. In this review, we illustrate the molecular mechanisms of EMT in the emergence of cancer metastasis. We then present the role of natural compounds in the suppression of EMT pathways in different cancers to overcome cancer cell drug resistance and improve tumor chemotherapy. HighlightsDrug-resistance is one of the obstacles to cancer treatment.EMT signaling pathways have been correlated to tumor invasion, metastasis, and drug-resistance.Various studies on the relationship between EMT and resistance to chemotherapy agents were reviewed.Different anticancer natural products with EMT inhibitory properties and drug resistance reversal effects were compared.

Autophagy Modulation and Cancer Combination Therapy: A Smart Approach in Cancer Therapy

The autophagy pathway is the process whereby cells keep cellular homeostasis and respond to stress via recycling their damaged cellular proteins, organelles, and other cellular components. In the context of cancer, autophagy is a dual-edge sword pro- and anti-tumorigenic role depending on the oncogenic context and stage of tumorigenesis. Cancer cells have a higher dependency on autophagy compared with normal cells because of cellular damages and high demands for energy. The carbon, nitrogen, and molecular oxygen are building blocks for highly proliferative cancer cells which extremely depend on glutaminolysis and aerobic glycolysis; when a cancer cell is restricted to glucose and glutamine, it initiates to activate a stress response pathway using autophagy. Oncogenic tyrosine kinases (OncTKs) and receptor tyrosine kinases (RTKs) activation result in autophagy modulation through activation of the PI3K/AKT/mTORC1 and RAS/MAPK signaling pathways. Targeted inhibition of tyrosine kinases (TKs) and RTKs have recently been considered as cancer therapy but drug resistance and cancer relapse continue to be a major limitation of tyrosine kinase inhibitors (TKIs). Manipulation of autophagy pathway along with TKIs may be a promising strategy to circumvent unknown existing drug-resistance mechanisms that may emerge in a treated patient. In this way, clinical trials are ongoing to modulate autophagy to treat cancer. This review aims to summarize the combination therapy of autophagy affecting compounds with anticancer drugs which target cell signaling pathways, metabolism mechanisms, and epigenetics modification to improve therapeutic efficacy against cancers.

High Circulating Sonic Hedgehog Protein Is Associated With Poor Outcome in EGFR-Mutated Advanced NSCLC Treated With Tyrosine Kinase Inhibitors

Introduction

Growing preclinical evidence has suggested that the Sonic hedgehog (Shh) pathway is involved in resistance to tyrosine kinase inhibitor (TKI) therapy for EGFR-mutated (EGFRm) non-small cell lung cancer (NSCLC). However, little is known concerning the prognostic value of this pathway in this context.

Materials and Methods

We investigated the relationship between plasma levels of Shh and EGFRm NSCLC patients’ outcome with EGFR TKIs. We included 74 consecutive patients from two institutions with EGFRm advanced NSCLC treated by EGFR TKI as first-line therapy. Plasma samples were collected longitudinally for each patient and were analyzed for the expression of Shh using an ELISA assay. The activation of the Shh–Gli1 pathway was assessed through immunohistochemistry (IHC) of Gli1 and RT-qPCR analysis of the transcripts of Gli1 target genes in 14 available tumor biopsies collected at diagnosis (baseline).

Results

Among the 74 patients, only 61 had baseline (diagnosis) plasma samples, while only 49 patients had plasma samples at the first evaluation. Shh protein was detectable in all samples at diagnosis (n = 61, mean = 1,041.2 ± 252.5 pg/ml). Among the 14 available tumor biopsies, nuclear expression of Gli1 was observed in 57.1% (8/14) of patients’ biopsies. Shh was significantly (p < 0.05) enriched in youth (age < 68), male, nonsmokers, patients with a PS > 1, and patients presenting more than 2 metastatic sites and L858R mutation. Higher levels of Shh correlated with poor objective response to TKI, shorter progression-free survival (PFS), and T790M-independent mechanism of resistance. In addition, the rise of plasma Shh levels along the treatment was associated with the emergence of drug resistance in patients presenting an initial good therapy response.

Conclusion

These data support that higher levels of plasma Shh at diagnosis and increased levels of Shh along the course of the disease are related to the emergence of TKI resistance and poor outcome for EGFR-TKI therapy, suggesting that Shh levels could stand both as a prognostic and as a resistance biomarker for the management of EGFR-mutated NSCLC patients treated with EGFR-TKI.

Defining the Role of GLI/Hedgehog Signaling in Chemoresistance: Implications in Therapeutic Approaches

Insight into cancer signaling pathways is vital in the development of new cancer treatments to improve treatment efficacy. A relatively new but essential developmental signaling pathway, namely Hedgehog (Hh), has recently emerged as a major mediator of cancer progression and chemoresistance. The evolutionary conserved Hh signaling pathway requires an in-depth understanding of the paradigm of Hh signaling transduction, which is fundamental to provide the necessary means for the design of novel tools for treating cancer related to aberrant Hh signaling. This review will focus substantially on the canonical Hh signaling and the treatment strategies employed in different studies, with special emphasis on the molecular mechanisms and combination treatment in regard to Hh inhibitors and chemotherapeutics. We discuss our views based on Hh signaling's role in regulating DNA repair machinery, autophagy, tumor microenvironment, drug inactivation, transporters, epithelial-to-mesenchymal transition, and cancer stem cells to promote chemoresistance. The understanding of this Achilles' Heel in cancer may improve the therapeutic outcome for cancer therapy.

The Roles of the Let-7 Family of MicroRNAs in the Regulation of Cancer Stemness

Cancer has long been viewed as a disease of normal development gone awry. Cancer stem-like cells (CSCs), also termed as tumor-initiating cells (TICs), are increasingly recognized as a critical tumor cell population that drives not only tumorigenesis but also cancer progression, treatment resistance and metastatic relapse. The let-7 family of microRNAs (miRNAs), first identified in C. elegans but functionally conserved from worms to human, constitutes an important class of regulators for diverse cellular functions ranging from cell proliferation, differentiation and pluripotency to cancer development and progression. Here, we review the current state of knowledge regarding the roles of let-7 miRNAs in regulating cancer stemness. We outline several key RNA-binding proteins, long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs) involved in the regulation of let-7 biogenesis, maturation and function. We then highlight key gene targets and signaling pathways that are regulated or mutually regulated by the let-7 family of miRNAs to modulate CSC characteristics in various types of cancer. We also summarize the existing evidence indicating distinct metabolic pathways regulated by the let-7 miRNAs to impact CSC self-renewal, differentiation and treatment resistance. Lastly, we review current preclinical studies and discuss the clinical implications for developing let-7-based replacement strategies as potential cancer therapeutics that can be delivered through different platforms to target CSCs and reduce/overcome treatment resistance when applied alone or in combination with current chemo/radiation or molecularly targeted therapies. By specifically targeting CSCs, these strategies have the potential to significantly improve the efficacy of cancer therapies.

Cordyceps militaris Exerts Anticancer Effect on Non-Small Cell Lung Cancer by Inhibiting Hedgehog Signaling via Suppression of TCTN3

This study aimed to investigate the effect of Cordyceps militaris extract on the proliferation and apoptosis of non–small cell lung cancer (NSCLC) cells and determine the underlying mechanisms. We performed a CCK-8 assay to detect cell proliferation, detection of morphological changes through transmission electron microscopy (TEM), annexin V–FITC/PI double staining to analyze apoptosis, and immunoblotting to measure the protein expression of apoptosis and hedgehog signaling–related proteins, with C militaris treated NSCLC cells. In this study, we first found that C militaris reduced the viability and induced morphological disruption in NSCLC cells. The gene expression profiles indicated a reprogramming pattern of genes and transcription factors associated with the action of TCTN3 on NSCLC cells. We also confirmed that the C militaris–induced inhibition of TCTN3 expression affected the hedgehog signaling pathway. Immunoblotting indicated that C militaris–mediated TCTN3 downregulation induced apoptosis in NSCLC cells, involved in the serial activation of caspases. Moreover, we demonstrated that the C militaris negatively modulated GLI1 transcriptional activity by suppressing SMO/PTCH1 signaling, which affects the intrinsic apoptotic pathway. When hedgehog binds to the PTCH1, SMO dissociates from PTCH1 inhibition at cilia. As a result, the active GLI1 translocates to the nucleus. C militaris clearly suppressed GLI1 nuclear translocation, leading to Bcl-2 and Bcl-xL down-regulation. These results suggested that C militaris induced NSCLC cell apoptosis, possibly through the downregulation of SMO/PTCH1 signaling and GLI1 activation via inhibition of TCTN3. Taken together, our findings provide new insights into the treatment of NSCLC using C militaris.

Markers and Reporters to Reveal the Hierarchy in Heterogeneous Cancer Stem Cells

A subpopulation within cancer, known as cancer stem cells (CSCs), regulates tumor initiation, chemoresistance, and metastasis. At a closer look, CSCs show functional heterogeneity and hierarchical organization. The present review is an attempt to assign marker profiles to define the functional heterogeneity and hierarchical organization of CSCs, based on a series of single-cell analyses. The evidences show that analogous to stem cell hierarchy, self-renewing Quiescent CSCs give rise to the Progenitor CSCs with limited proliferative capacity, and later to a Progenitor-like CSCs, which differentiates to Proliferating non-CSCs. Functionally, the CSCs can be tumor-initiating cells (TICs), drug-resistant CSCs, or metastasis initiating cells (MICs). Although there are certain marker profiles used to identify CSCs of different cancers, molecules like CD44, CD133, ALDH1A1, ABCG2, and pluripotency markers [Octamer binding transcriptional factor 4 (OCT4), SOX2, and NANOG] are used to mark CSCs of a wide range of cancers, ranging from hematological malignancies to solid tumors. Our analysis of the recent reports showed that a combination of these markers can demarcate the heterogeneous CSCs in solid tumors. Reporter constructs are widely used for easy identification and quantification of marker molecules. In this review, we discuss the suitability of reporters for the widely used CSC markers that can define the heterogeneous CSCs. Since the CSC-specific functions of CD44 and CD133 are regulated at the post-translational level, we do not recommend the reporters for these molecules for the detection of CSCs. A promoter-based reporter for ABCG2 may also be not relevant in CSCs, as the expression of the molecule in cancer is mainly regulated by promoter demethylation. In this context, a dual reporter consisting of one of the pluripotency markers and ALDH1A1 will be useful in marking the heterogeneous CSCs. This system can be easily adapted to high-throughput platforms to screen drugs for eliminating CSCs.

Treatment of Cutaneous Melanoma Harboring SMO p.Gln216Arg Mutation with Imiquimod: An Old Drug with New Results

Melanoma is the most lethal form of skin cancer and its incidence is growing worldwide. In the last ten years, the therapeutic scenario of this disease has been revolutionized by the introduction of targeted therapies and immune-checkpoint inhibitors. However, in patients with many lesions and bulky tumors, in which surgery is no longer feasible, there is a need for new treatment options. Here we report, for the first time to our knowledge, a clinical case where a melanoma patient harboring the SMO p.Gln216Arg mutation has been treated with imiquimod, showing a complete and durable response. To better explain this outstanding response to the treatment, we transfected a melanoma cell line (MeWo) with the SMO p.Gln216Arg mutation in order to evaluate its role in response to the imiquimod treatment. Moreover, to better demonstrate that the antitumor activity of imiquimod was due to its role in suppressing the oncogenic SMO signaling pathway, independently of its immune modulating function, an in vivo experiment has been performed. This clinical case opens up a new scenario for the treatment of melanoma patients identifying a new potentially druggable target.

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

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

Targeting cancer stem cells for reversing therapy resistance: mechanism, signaling, and prospective agents

Cancer stem cells (CSCs) show a self-renewal capacity and differentiation potential that contribute to tumor progression and therapy resistance. However, the underlying processes are still unclear. Elucidation of the key hallmarks and resistance mechanisms of CSCs may help improve patient outcomes and reduce relapse by altering therapeutic regimens. Here, we reviewed the identification of CSCs, the intrinsic and extrinsic mechanisms of therapy resistance in CSCs, the signaling pathways of CSCs that mediate treatment failure, and potential CSC-targeting agents in various tumors from the clinical perspective. Targeting the mechanisms and pathways described here might contribute to further drug discovery and therapy.

Scutellariabarbata D. Don extraction selectively targets stemness-prone NSCLC cells by attenuating SOX2/SMO/GLI1 network loop

ETHNOPHARMACOLOGICAL RELEVANCE

Scutellariabarbata D. Don extraction (SBE), a traditional Chinese medicine, has been proved effective against various malignant disorders in clinics with tolerable side-effects when administered alone or in combination with conventional chemotherapeutic regimens.

AIM OF THIS STUDY

Multi-drug resistance of cancer is attributed to existence of cancer stemness-prone cells that harbor aberrantly high activation of Sonic Hedgehog (SHH) cascade. Our previous study has demonstrated that SBE sensitized non-small cell lung cancer (NSCLC) cells to Cisplatin (DDP) treatment by downregulating SHH pathway. Yet, whether SBE could prohibit proliferation of cancer stemness-prone cells and its underlying molecular mechanisms remain to be investigated. In this article, we further investigated intervention of SBE on NSCLC cell stemness-associated phenotypes and its potential mode of action.

MATERIALS AND METHODS

CCK-8 and clonal formation detection were used to measure the anti-proliferative potency of SBE against NSCLC and normal epithelial cells. Sphere formation assay and RQ-PCR were used to detect proliferation of cancer stemness cells and associated marker expression upon SBE incubation. Mechanistically, DARTS-WB and SPR were used to unveil binding target of SBE. Immunodeficient mice were implanted with patient derived tumor bulk for in vivo validation of anti-cancer effect of SBE.

RESULTS

SBE selectively attenuated proliferation and stemness-like phenotypes of NSCLC cells rather than bronchial normal epithelial cells. Drug-protein interaction analysis revealed that SBE could directly bind with stem cell-specific transcription factor sex determining region Y-box 2 (SOX2) and interfere with the SOX2/SMO/GLI1 positive loop. In vivo assay using patient-derived xenografts (PDXs) model further proved that SBE diminished tumor growth and SOX2 expression in vivo.

CONCLUSION

Our data indicate that SBE represses stemness-related features of NSCLC cells via targeting SOX2 and may serve as an alternative therapeutic option for clinic treatment.

HEDGEHOG/GLI Modulates the PRR11-SKA2 Bidirectional Transcription Unit in Lung Squamous Cell Carcinomas

We previously demonstrated that proline-rich protein 11 (PRR11) and spindle and kinetochore associated 2 (SKA2) constituted a head-to-head gene pair driven by a prototypical bidirectional promoter. This gene pair synergistically promoted the development of non-small cell lung cancer. However, the signaling pathways leading to the ectopic expression of this gene pair remains obscure. In the present study, we first analyzed the lung squamous cell carcinoma (LSCC) relevant RNA sequencing data from The Cancer Genome Atlas (TCGA) database using the correlation analysis of gene expression and gene set enrichment analysis (GSEA), which revealed that the PRR11-SKA2 correlated gene list highly resembled the Hedgehog (Hh) pathway activation-related gene set. Subsequently, GLI1/2 inhibitor GANT-61 or GLI1/2-siRNA inhibited the Hh pathway of LSCC cells, concomitantly decreasing the expression levels of PRR11 and SKA2. Furthermore, the mRNA expression profile of LSCC cells treated with GANT-61 was detected using RNA sequencing, displaying 397 differentially expressed genes (203 upregulated genes and 194 downregulated genes). Out of them, one gene set, including BIRC5, NCAPG, CCNB2, and BUB1, was involved in cell division and interacted with both PRR11 and SKA2. These genes were verified as the downregulated genes via RT-PCR and their high expression significantly correlated with the shorter overall survival of LSCC patients. Taken together, our results indicate that GLI1/2 mediates the expression of the PRR11-SKA2-centric gene set that serves as an unfavorable prognostic indicator for LSCC patients, potentializing new combinatorial diagnostic and therapeutic strategies in LSCC.

Downregulation of miR-506-3p Facilitates EGFR-TKI Resistance through Induction of Sonic Hedgehog Signaling in Non-Small-Cell Lung Cancer Cell Lines

Non-small-cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation eventually develop resistance to EGFR-targeted tyrosine kinase inhibitors (TKIs). Treatment resistance remains the primary obstacle to the successful treatment of NSCLC. Although drug resistance mechanisms have been studied extensively in NSCLC, the regulation of these mechanisms has not been completely understood. Recently, increasing numbers of microRNAs (miRNAs) are implicated in EGFR-TKI resistance, indicating that miRNAs may serve as novel targets and may hold promise as predictive biomarkers for anti-EGFR therapy. MicroRNA-506 (miR-506) has been identified as a tumor suppressor in many cancers, including lung cancer; however, the role of miR-506 in lung cancer chemoresistance has not yet been addressed. Here we report that miR-506-3p expression was markedly reduced in erlotinib-resistant (ER) cells. We identified Sonic Hedgehog (SHH) as a novel target of miR-506-3p, aberrantly activated in ER cells. The ectopic overexpression of miR-506-3p in ER cells downregulates SHH signaling, increases E-cadherin expression, and inhibits the expression of vimentin, thus counteracting the epithelial-mesenchymal transition (EMT)-mediated chemoresistance. Our results advanced our understanding of the molecular mechanisms underlying EGFR-TKI resistance and indicated that the miR-506/SHH axis might represent a novel therapeutic target for future EGFR mutated lung cancer treatment.

Let-7c regulated epithelial-mesenchymal transition leads to osimertinib resistance in NSCLC cells with EGFR T790M mutations

Epidermal growth factor receptor- tyrosine kinase inhibitors (EGFR-TKIs) have shown promise against non-small cell lung cancers (NSCLCs) in clinics but the utility is often short-lived because of T790M mutations in EGFR that help evade TKIs’ action. Osimertinib is the third and latest generation TKI that targets EGFRs with T790M mutations. However, there are already reports on acquired resistance against Osimertinib. Recent work has revealed the role that miRNAs, particularly tumor suppressor let-7c, play in the invasiveness and acquired resistance of NSCLCs, but the mechanistic details, particularly in Osimertinib resistance, remain elusive. Using two cells lines, H1975 (endogenous T790M mutation) and HCC827-T790M (with acquired T790M mutation), we found that let-7c is a regulator of EMT, as well as it affects CSC phenotype. In both the cell lines, transfection with pre-let-7c led to reversal of EMT as studied through EMT markers e-cadherin and ZEB1. This resulted in reduced proliferation and invasion. Conversely, reduced expression of let-7c through anti-let-7c transfections significantly increased proliferation and invasion of lung cancer cells. Expression of let-7c was functionally relevant as EMT correlated with resistance to Osimertinib. High let-7c expression reversed EMT and made cells sensitive to Osimertinib, and vice versa. WNT1 and TCF-4 were found to be two targets of let-7c which were epigenetic suppressed by let-7c through increased methylation. In vivo, pre-let-7c inhibited while anti-let-7c potentiated tumor growth and WNT1 and TCF-4 were downregulated in xenografts with pre-let-7c. Silencing of both WNT1 and TCF-4 resulted in potentiation of Osimertinib action. Our results suggest an important role of let-7c in regulating EMT and the resulting Osimertinib resistance in T790M NSCLCs. More clinical studies need to be performed to fully understand the translational relevance of this novel mechanism.

miR-200 affects tamoxifen resistance in breast cancer cells through regulation of MYB

Resistance to tamoxifen is a major clinical challenge. Research in recent years has identified epigenetic changes as mediated by dysregulated miRNAs that can possibly play a role in resistance to tamoxifen in breast cancer patients expressing estrogen receptor (ER). We report here elevated levels of EMT markers (vimentin and ZEB1/2) and reduced levels of EMT-regulating miR-200 (miR-200b and miR-200c) in ER-positive breast cancer cells, MCF-7, that were resistant to tamoxifen, in contrast with the naïve parental MCF-7 cells that were sensitive to tamoxifen. Further, we established regulation of c-MYB by miR-200 in our experimental model. C-MYB was up-regulated in tamoxifen resistant cells and its silencing significantly decreased resistance to tamoxifen and the EMT markers. Forced over-expression of miR-200b/c reduced c-MYB whereas reduced expression of miR-200b/c resulted in increased c-MYB We further confirmed the results in other ER-positive breast cancer cells T47D cells where forced over-expression of c-MYB resulted in induction of EMT and significantly increased resistance to tamoxifen. Thus, we identify a novel mechanism of tamoxifen resistance in breast tumor microenvironment that involves miR-200-MYB signaling.

Research progress on the relationship between lung cancer drug-resistance and microRNAs

Lung cancer, a malignant tumor with the highest death rate of cancer, seriously endangers human health. And its pathogenesis and mechanism of drug resistance has been partially clarified, especially for the signal pathway of epidermal growth factor receptor (EGFR). The targeting therapy of EGFR signaling pathway in non-small cell lung cancer (NSCLC) has achieved a certain effect, but the two mutation of EGFR and other mechanisms of lung cancer resistance still greatly reduce the therapeutic effect of chemotherapy on it. MicroRNA is an endogenous non coding RNA, which has a regulatory function after transcriptional level. Recent studies on the mechanism of lung cancer resistance have found that a variety of microRNAs are related to the mechanism of lung cancer drug-resistance. They can regulate lung cancer resistance by participating in signal pathways, drug resistance genes and cell apoptosis, thus affecting the sensitivity of cancer cells to drugs. Therefore, microRNAs can be used as a specific target for the treatment of lung cancer and plays a vital role in the early diagnosis, prognosis and treatment of lung cancer. This article reviews the mechanisms of lung cancer resistance and its relationship with microRNAs.

LncRNA TP73-AS1 interacted with miR-141-3p to promote the proliferation of non-small cell lung cancer

INTRODUCTION

Recent studies have shown that long non-coding RNAs (lncRNAs) are involved in a variety of biological processes and diseases in humans, including cancer. However, the exact effects and molecular mechanisms of TP73-AS1 in non-small cell lung cancer (NSCLC) progression are still unknown. The present study is aimed to reveal the detailed functions and the mechanism of TP73-AS1 in the regulation of NSCLC cell proliferation.

MATERIAL AND METHODS

TP73-AS1 expression in NSCLC tissues and cell lines was determined using real-time PCR assays. The functions of TP73-AS1 in the regulation of NSCLC cell proliferation was evaluated using BrdU assays. The interaction between TP73-AS1 and miR-141-3p was confirmed using luciferase report gene assays.

RESULTS

TP73-AS1 was upregulated in NSCLC tissues and cell lines. However, when knockdown of TP73-AS1 inhibited the NSCLC proliferation. By using online tools, we screened out miR-141-3p may combined with TP73-AS1. With use of luciferase assays, we confirmed that miR-141-3p could directly bind to TP73-AS1. In NSCLC tissues, miR-141-3p was down-regulated; TP73-AS1 was inversely correlated with miR-141-3p.

CONCLUSIONS

Our data suggest that TP73-AS1 might be an oncogenic lncRNA that promotes proliferation of NSCLC and might be regarded as a therapeutic target in NSCLC.

House dust mite induces Sonic hedgehog signaling that mediates epithelial‑mesenchymal transition in human bronchial epithelial cells

Epithelial‑mesenchymal transition (EMT) provides a valuable source of fibroblasts that produce extracellular matrix in airway walls. The Sonic hedgehog (SHH) signaling pathway plays an essential role in regulating tissue turnover and homeostasis. SHH is strikingly upregulated in the bronchial epithelia during asthma. Snail1 is a major target of SHH signaling, which regulates EMT and fibroblast motility. The present study was designed to ascertain whether the combination of house dust mite (HDM) and transforming growth factor β1 (TGF‑β1) could induce EMT via the SHH signaling pathway in human bronchial epithelial cells (HBECs). HBEC cultures were treated with HDM/TGF‑β1 for different periods of time. The involvement of SHH signaling and EMT biomarkers was evaluated by quantitative real‑time PCR, western blotting and immunofluorescence staining. Small‑interfering RNA (siRNA) for glioma‑associated antigen‑1 (Gli1) or cyclopamine was used to inhibit SHH signaling in HBECs. HBECs stimulated by HDM/TGF‑β1 exhibited morphological features of EMT. E‑cadherin (an epithelial marker) was decreased after a 72‑h exposure to HDM/TGF‑β1 compared to that in the control cells, and the expression of type I collagen and FSP1 (mesenchymal markers) was increased. HDM/TGF‑β1 activated the SHH signaling pathway in HBECs, which led to Gli1 nuclear translocation and the transcriptional activation of Snail1 expression. Moreover, gene silencing or the pharmacological inhibition of Gli1 ameliorated EMT. In summary, these findings suggest that HDM/TGF‑β1 may induce EMT in HBECs via an SHH signaling mechanism. Inhibition of SHH signaling may be a novel therapeutic method for preventing airway remodeling in asthma.