Lung cancer stem cells: The root of resistance

IGF-1-mediated FOXC1 overexpression induces stem-like properties through upregulating CBX7 and IGF-1R in esophageal squamous cell carcinoma

Substantial evidence attests to the pivotal role of cancer stem cells (CSC) in both tumorigenesis and drug resistance. A member of the forkhead box (FOX) family, FOXC1, assumes significance in embryonic development and organogenesis. Furthermore, FOXC1 functions as an overexpressed transcription factor in various tumors, fostering proliferation, enhancing migratory capabilities, and promoting drug resistance, while maintaining stem-cell-like properties. Despite these implications, scant attention has been devoted to its role in esophageal squamous cell carcinoma. Our investigation revealed a pronounced upregulation of FOXC1 expression in ESCC, correlating with a poor prognosis. The downregulation of FOXC1 demonstrated inhibitory effects on ESCC tumorigenesis, proliferation, and tolerance to chemotherapeutic agents, concurrently reducing the levels of stemness-related markers CD133 and CD44. Further studies validated that FOXC1 induces ESCC stemness by transactivating CBX7 and IGF-1R. Additionally, IGF-1 activated the PI3K/AKT/NF-κB and MEK/ERK/NF-κB pathways through its binding to IGF-1R, thereby augmenting FOXC1 expression. Conversely, suppressing FOXC1 impeded ESCC stemness induced by IGF-1. The presence of a positive feedback loop, denoted by IGF-1-FOXC1-IGF-1R, suggests the potential of FOXC1 as a prognostic biomarker for ESCC. Taken together, targeting the IGF-1-FOXC1-IGF-1R axis emerges as a promising approach for anti-CSC therapy in ESCC.

Attenuation of PI3K-Akt-mTOR Pathway to Reduce Cancer Stemness on Chemoresistant Lung Cancer Cells by Shikonin and Synergy with BEZ235 Inhibitor

Lung cancer is considered the number one cause of cancer-related deaths worldwide. Although current treatments initially reduce the lung cancer burden, relapse occurs in most cases; the major causes of mortality are drug resistance and cancer stemness. Recent investigations have provided evidence that shikonin generates various bioactivities related to the treatment of cancer. We used shikonin to treat multi-resistant non-small lung cancer cells (DOC-resistant A549/D16, VCR-resistant A549/V16 cells) and defined the anti-cancer efficacy of shikonin. Our results showed shikonin induces apoptosis in these ABCB1-dependent and independent chemoresistance cancer sublines. Furthermore, we found that low doses of shikonin inhibit the proliferation of lung cancer stem-like cells by inhibiting spheroid formation. Concomitantly, the mRNA level and protein of stemness genes (Nanog and Oct4) were repressed significantly on both sublines. Shikonin reduces the phosphorylated Akt and p70s6k levels, indicating that the PI3K/Akt/mTOR signaling pathway is downregulated by shikonin. We further applied several signaling pathway inhibitors that have been used in anti-cancer clinical trials to test whether shikonin is suitable as a sensitizer for various signaling pathway inhibitors. In these experiments, we found that low doses shikonin and dual PI3K-mTOR inhibitor (BEZ235) have a synergistic effect that inhibits the spheroid formation from chemoresistant lung cancer sublines. Inhibiting the proliferation of lung cancer stem cells is believed to reduce the recurrence of lung cancer; therefore, shikonin's anti-drug resistance and anti-cancer stem cell activities make it a highly interesting molecule for future combined lung cancer therapy.

A novel lung cancer stem cell extracellular vesicles lncRNA ROLLCSC modulate non-stemness cancer cell plasticity through miR-5623-3p and miR-217-5p targeting lipid metabolism

BACKGROUND

The high mortality rate of lung cancer is largely attributed to metastasis. Lung cancer stem cells (CSC) are conducive to cancer heterogeneity. Long noncoding RNAs are known to participate in various biological processes regulating the development of lung cancer. However, characterization of the role and mechanisms of lncRNA in lung cancer metastasis remains a challenge.

RESULTS

We demonstrate that ROLLCSC, a highly expressed lncRNA in LLC-SDs, promotes the metastasis of the low metastatic LLCs both in vitro and in vivo. ROLLCSC can be transferred from LLC-SD to LLC through encapsulation in extracellular vesicles (EVs), ultimately leading to the enhancement of the metastatic phenotype of LLCs. Mechanistically, we demonstrate that the pro-metastatic activity of ROLLCSC is achieved through its function as a competing endogenous RNA (ceRNA) of miR-5623-3p and miR-217-5p to stimulate lipid metabolism.

CONCLUSION

In this study, we have characterized ROLLCSC, a novel lncRNA, as a pivotal regulator in the metastasis of lung cancer, highlighting its potential as a therapeutic target. Specifically, we show that ROLLCSC is encapsulated by the EVs of LLC-SDs and transmitted to the LLCs, where it acts as a ceRNA of miR-5623-3p and miR-217-5p to stimulate lipid metabolism and ultimately augments metastatic colonization of LLCs.

The Relationship between Trop-2, Chemotherapeutic Drugs, and Chemoresistance

Trop-2 is a highly conserved one-pass transmembrane mammalian glycoprotein that is normally expressed in tissues such as the lung, intestines, and kidney during embryonic development. It is overexpressed in many epithelial cancers but is absent in non-epithelial tumors. Trop-2 is an intracellular calcium signal transducer that participates in the promotion of cell proliferation, migration, invasion, metastasis, and probably stemness. It also has some tumor suppressor effects. The pro-tumoral actions have been thoroughly investigated and reported. However, Trop-2's activity in chemoresistance is less well known. We review a possible relationship between Trop-2, chemotherapy, and chemoresistance. We conclude that there is a clear role for Trop-2 in some specific chemoresistance events. On the other hand, there is no clear evidence for its participation in multidrug resistance through direct drug transport. The development of antibody conjugate drugs (ACD) centered on anti-Trop-2 monoclonal antibodies opened the gates for the treatment of some tumors resistant to classic chemotherapies. Advanced urothelial tumors and breast cancer were among the first malignancies for which these ACDs have been employed. However, there is a wide group of other tumors that may benefit from anti-Trop-2 therapy as soon as clinical trials are completed.

Combined in vitro/in vivo genome-wide CRISPR screens in triple negative breast cancer identify cancer stemness regulators in paclitaxel resistance

Triple negative breast cancer (TNBC) is defined as lacking the expressions of estrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2). TNBC patients exhibit relatively poor clinical outcomes due to lack of molecular markers for targeted therapies. As such chemotherapy often remains the only systemic treatment option for these patients. While chemotherapy can initially help shrink TNBC tumor size, patients eventually develop resistance to drug, leading to tumor recurrence. We report a combined in vitro/in vivo genome-wide CRISPR synthetic lethality screening approach in a relevant TNBC cell line model to identify several targets responsible for the chemotherapy drug, paclitaxel resistance. Computational analysis integrating in vitro and in vivo data identified a set of genes, for which specific loss-of-function deletion enhanced paclitaxel resistance in TNBC. We found that several of these genes (ATP8B3, FOXR2, FRG2, HIST1H4A) act as cancer stemness negative regulators. Finally, using in vivo orthotopic transplantation TNBC models we showed that FRG2 gene deletion reduced paclitaxel efficacy and promoted tumor metastasis, while increasing FRG2 expression by means of CRISPR activation efficiently sensitized TNBC tumors to paclitaxel treatment and inhibited their metastatic abilities. In summary, the combined in vitro/in vivo genome-wide CRISPR screening approach proved effective as a tool to identify novel regulators of paclitaxel resistance/sensitivity and highlight the FRG2 gene as a potential therapeutical target overcoming paclitaxel resistance in TNBC.

Exploring the dynamic interplay between cancer stem cells and the tumor microenvironment: implications for novel therapeutic strategies

Cancer stem cells (CSCs) have emerged as key contributors to tumor initiation, growth, and metastasis. In addition, CSCs play a significant role in inducing immune evasion, thereby compromising the effectiveness of cancer treatments. The reciprocal communication between CSCs and the tumor microenvironment (TME) is observed, with the TME providing a supportive niche for CSC survival and self-renewal, while CSCs, in turn, influence the polarization and persistence of the TME, promoting an immunosuppressive state. Consequently, these interactions hinder the efficacy of current cancer therapies, necessitating the exploration of novel therapeutic approaches to modulate the TME and target CSCs. In this review, we highlight the intricate strategies employed by CSCs to evade immune surveillance and develop resistance to therapies. Furthermore, we examine the dynamic interplay between CSCs and the TME, shedding light on how this interaction impacts cancer progression. Moreover, we provide an overview of advanced therapeutic strategies that specifically target CSCs and the TME, which hold promise for future clinical and translational studies in cancer treatment.

Molecular and immunological mechanisms of clonal evolution in multiple myeloma

Multiple myeloma (MM) is a hematologic malignancy characterized by the proliferation of clonal plasma cells in the bone marrow (BM). It is known that early genetic mutations in post-germinal center B/plasma cells are the cause of myelomagenesis. The acquisition of additional chromosomal abnormalities and distinct mutations further promote the outgrowth of malignant plasma cell populations that are resistant to conventional treatments, finally resulting in relapsed and therapy-refractory terminal stages of MM. In addition, myeloma cells are supported by autocrine signaling pathways and the tumor microenvironment (TME), which consists of diverse cell types such as stromal cells, immune cells, and components of the extracellular matrix. The TME provides essential signals and stimuli that induce proliferation and/or prevent apoptosis. In particular, the molecular pathways by which MM cells interact with the TME are crucial for the development of MM. To generate successful therapies and prevent MM recurrence, a thorough understanding of the molecular mechanisms that drive MM progression and therapy resistance is essential. In this review, we summarize key mechanisms that promote myelomagenesis and drive the clonal expansion in the course of MM progression such as autocrine signaling cascades, as well as direct and indirect interactions between the TME and malignant plasma cells. In addition, we highlight drug-resistance mechanisms and emerging therapies that are currently tested in clinical trials to overcome therapy-refractory MM stages.

Regulating POLR3G by MicroRNA-26a-5p as a promising therapeutic target of lung cancer stemness and chemosensitivity

Cancer stem cells (CSCs) identified in lung cancer exhibit resistance to chemotherapy, radiotherapy, and targeted therapy. Therefore, a technology for controlling CSCs is needed to overcome such resistance to cancer therapy. Various evidences about the association between epithelial-mesenchymal transition related transcriptomic alteration and acquisition of CSC phenotype have been proposed recently. Down-regulated miR-26a-5p is closely related to mesenchymal-like lung cancer cell lines. These findings suggest that miR-26a-5p might be involved in lung cancer stemness. RNA polymerase III subunit G (POLR3G) was selected as a candidate target of miR-26a-5p related to cancer stemness. It was found that miR-26a-5p directly regulates the expression of POLR3G.Overexpression of miR-26a-5p induced a marked reduction of colony formation and sphere formation. Co-treatment of miR-26a-5p and paclitaxel decreased cell growth, suggesting that miR-26a-5p might play a role as a chemotherapy sensitizer. In the cancer genome atlas data, high miR-26a-5p and low POLR3G expression were also related to higher survival rate of patients with lung adenocarcinoma. These results suggest that miR-26a-5p can suppress lung cancer stemness and make cancer cell become sensitive to chemotherapy. This finding provides a novel insight into a potential lung cancer treatment by regulating stemness.

Unmasking the Deceptive Nature of Cancer Stem Cells: The Role of CD133 in Revealing Their Secrets

Cancer remains a leading cause of death globally, and its complexity poses a significant challenge to effective treatment. Cancer stem cells and their markers have become key players in tumor growth and progression. CD133, a marker in various cancer types, is an active research area as a potential therapeutic target. This article explores the role of CD133 in cancer treatment, beginning with an overview of cancer statistics and an explanation of cancer stem cells and their markers. The rise of CD133 is discussed, including its structure, functions, and occurrence in different cancer types. Furthermore, the article covers CD133 as a therapeutic target, focusing on gene therapy, immunotherapy, and approaches to affect CD133 expression. Nanoparticles such as gold nanoparticles and nanoliposomes are also discussed in the context of CD133-targeted therapy. In conclusion, CD133 is a promising therapeutic target for cancer treatment. As research in this area progresses, it is hoped that CD133-targeted therapies will offer new and effective treatment options for cancer patients in the future.

CA916798 predicts poor prognosis and promotes Gefitinib resistance for lung adenocarcinoma

Background

Our previous studies have identified CA916798 as a chemotherapy resistance-associated gene in lung cancer. However, the histopathological relevance and biological function of CA916798 in lung adenocarcinoma (LUAD) remains to be delineated. In this study, we further investigated and explored the clinical and biological significance of CA916798 in LUAD.

Methods

The relationship between CA916798 and clinical features of LUAD was analyzed by tissue array and online database. CCK8 and flow cytometry were used to measure cell proliferation and cell cycle of LUAD after knockdown of CA916798 gene. qRT-PCR and western blotting were used to detect the changes of cell cycle-related genes after knockdown or overexpression of CA916798. The tumorigenesis of LUAD cells was evaluated with or without engineering manipulation of CA916798 gene expression. Response to Gefitinib was evaluated using LUAD cells with forced expression or knockdown of CA916798.

Results

The analysis on LUAD samples showed that high expression of CA916798 was tightly correlated with pathological progression and poor prognosis of LUAD patients. A critical methylation site in promoter region of CA916798 gene was identified to be related with CA916798 gene expression. Forced expression of CA916798 relieved the inhibitory effects of WEE1 on CDK1 and facilitated cell cycle progression from G2 phase to M phase. However, knockdown of CA916798 enhanced WEE1 function and resulted in G2/M phase arrest. Consistently, chemical suppression of CDK1 dramatically inhibited G2/M phase transition in LUAD cells with high expression of CA916798. Finally, we found that CA916798 was highly expressed in Gefitinib-resistant LUAD cells. Exogenous expression of CA916798 was sufficient to endow Gefitinib resistance with tumor cells, but interference of CA916798 expression largely rescued response of tumor cells to Gefitinib.

Conclusions

CA916798 played oncogenic roles and was correlated with the development of Gefitinib resistance in LUAD cells. Therefore, CA916798 could be considered as a promising prognostic marker and a therapeutic target for LUAD.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-023-10735-3.

S-adenosylhomocysteine hydrolase-like protein 1 (AHCYL1) inhibits lung cancer tumorigenesis by regulating cell plasticity

BACKGROUND

Lung cancer is one of the most frequently diagnosed cancers characterized by high mortality, metastatic potential, and recurrence. Deregulated gene expression of lung cancer, likewise in many other solid tumors, accounts for their cell heterogeneity and plasticity. S-adenosylhomocysteine hydrolase-like protein 1 (AHCYL1), also known as Inositol triphosphate (IP(3)) receptor-binding protein released with IP(3) (IRBIT), plays roles in many cellular functions, including autophagy and apoptosis but AHCYL1 role in lung cancer is largely unknown.

RESULTS

Here, we analyzed the expression of AHCYL1 in Non-Small Cell Lung Cancer (NSCLC) cells from RNA-seq public data and surgical specimens, which revealed that AHCYL1 expression is downregulated in tumors and inverse correlated to proliferation marker Ki67 and the stemness signature expression. AHCYL1-silenced NSCLC cells showed enhanced stem-like properties in vitro, which correlated with higher expression levels of stem markers POU5F1 and CD133. Also, the lack of AHCYL1 enhanced tumorigenicity and angiogenesis in mouse xenograft models highlighting stemness features.

CONCLUSIONS

These findings indicate that AHCYL1 is a negative regulator in NSCLC tumorigenesis by modulating cell differentiation state and highlighting AHCYL1 as a potential prognostic biomarker for lung cancer.

TIM-4 orchestrates mitochondrial homeostasis to promote lung cancer progression via ANXA2/PI3K/AKT/OPA1 axis

Mitochondrial function and homeostasis are critical to the proliferation of lung cancer cells. T-cell immunoglobulin and mucin domain-containing molecule 4 (TIM-4) promotes the development and progression of lung cancer. However, the role of TIM-4 in mitochondria homeostasis in tumor cells remains completely unknown. In this study, we found that TIM-4 promoted growth and proliferation of lung cancer cells by the oxidative phosphorylation (OXPHOS) pathway. Consistently, inhibition of OXPHOS reversed TIM-4-induced proliferation of lung cancer cells. Notably, TIM-4 promoted mitochondrial fusion via enhancing L-OPA1 protein expression. Mechanistically, TIM-4 regulated protein of L-OPA1 through the PI3K/AKT pathway, and TIM-4 interacted with ANXA2 to promote the activation of PI3K/AKT signaling. Collectively, TIM-4 promotes oxidative phosphorylation of lung cancer cells to accelerate tumor progress via ANXA2/PI3K/AKT/OPA1 axis, which sheds significant new lights on the potential role of TIM-4 in regulating tumor cell metabolism.

Resveratrol suppresses lung cancer by targeting cancer stem-like cells and regulating tumor microenvironment

Increasing evidence indicate that cancer stem cells (CSCs) are the key driver of tumor initiation and recurrence. The cellular and soluble components of the tumor microenvironment (TME) impact on cancer initiation and progression, such as cytokines and chemokines. Thus, targeting CSCs and TME is a novel anti-cancer approach. Resveratrol (RES), a bioactive phytochemical extracted from various plants, exhibits tumor-suppressing activities in lung cancer, yet the mechanism remains poorly understood. Our data showed that the expression level of IL-6 was positively correlated with the presence of lung cancer stem-like cells (LCSCs) in human lung cancer tissues. In vitro results showed that IL-6 was highly elevated in lung cancer sphere-forming cells and could enhance the stemness of LCSCs, including tumor sphere formation ability, the percentage of CD133 positive cells, and the expression of LCSC specific markers (CD133, ALDH1A1 and Nanog). Simultaneously, our results confirmed that RES effectively inhibited LCSC properties, downregulated Wnt/β-catenin signaling and reduced IL-6 level in vitro and in vivo. Furthermore, we found RES treatment attenuated the activation of Wnt/β-catenin signaling by LiCl (GSK3β agonist). IL-6-promoted LCSC properties and Wnt/β-catenin signaling was also reversed by RES. Taken together, these data illustrated that RES inhibited lung cancer by targeting LCSCs and IL-6 in TME. The novel findings from this study provided evidence that RES exhibited multi-target effects on suppression of lung cancer and could be a novel potent cancer-preventive compound.

Inhibitory Effect and Mechanism of Ursolic Acid on Cisplatin-Induced Resistance and Stemness in Human Lung Cancer A549 Cells

The survival rate of lung cancer patients remains low largely due to chemotherapy resistance during treatment, and cancer stem cells (CSCs) may hold the key to targeting this resistance. Cisplatin is a chemotherapy drug commonly used in cancer treatment, yet the mechanisms of intrinsic cisplatin resistance have not yet been determined because lung CSCs are hard to identify. In this paper, we proposed a mechanism relating to the function of ursolic acid (UA), a new drug, in reversing the cisplatin resistance of lung cancer cells regulated by CSCs. Human lung cancer cell line A549 was selected as the model cell and treated to become a cisplatin-resistant lung cancer cell line (A549-CisR), which was less sensitive to cisplatin and showed an enhanced capability of tumor sphere formation. Furthermore, in the A549-CisR cell line expression, levels of pluripotent stem cell transcription factors Oct-4, Sox-2, and c-Myc were increased, and activation of the Jak2/Stat3 signaling pathway was promoted. When UA was applied to the cisplatin-resistant cells, levels of the pluripotent stem cell transcription factors were restrained by the inhibition of the Jak2/Stat3 signaling pathway, which reduced the enrichment of tumor stem cells, and in turn, reversed cisplatin resistance in lung cancer cells. Hence, as a potential antitumor drug, UA may be able to inhibit the enrichment of the lung CSC population by inhibiting the activation of the Jak2-Stat3 pathway and preventing the resistance of lung cancer cells to cisplatin.

Single-Cell Transcriptomics Unveils the Dedifferentiation Mechanism of Lung Adenocarcinoma Stem Cells

Lung adenocarcinoma (LUAD) is a major subtype of lung cancer, and its prognosis is still poor due to therapy resistance, metastasis, and recurrence. In recent years, increasing evidence has shown that the existence of lung cancer stem cells is responsible for the propagation, metastasis, therapy resistance, and recurrence of the tumor. During their transition to cancer stem cells, tumor cells need to inhibit cell differentiation and acquire invasive characteristics. However, our understanding of the property and role of such lung cancer stem cells is still limited. In this study, lung adenocarcinoma cancer stem cells (LCSCs) were enriched from the PC-9 cell line in a serum-free condition. PC-9 cells grew into spheres and showed higher survival rates when exposed to gefitinib: the drug used for the treatment of LUAD. Additionally, we found that the canonical stemness marker protein CD44 was significantly increased in the enriched LCSCs. Then, LCSCs were inoculated into the groin of nude mice for 1.5 months, and tumors were detected in the animals, indicating the strong stemness of the cells. After that, we performed single-cell RNA sequencing (scRNA-seq) on 7320 LCSCs and explored the changes in their transcriptomic signatures. We identified cell populations with a heterogeneous expression of cancer stem marker genes in LCSCs and subsets with different degrees of differentiation. Further analyses revealed that the activation of the FOXM1 (oncoprotein) transcription factor is a key factor in cell dedifferentiation, which enables tumor cells to acquire an epithelial-mesenchymal transition phenotype and increases the LCSC surface marker CD44. Moreover, we found that the combination of CD44, ABCG2, and ALCAM was a specific marker for LCSCs. In summary, this study identified the potential factors and molecular mechanisms underlying the stemness properties of LUAD cancer cells; it could also provide insight into developing novel and effective therapeutic approaches.

Dinactin: A New Antitumor Antibiotic with Cell Cycle Progression and Cancer Stemness Inhibiting Activities in Lung Cancer

Lung cancer, especially non-small cell lung cancer (NSCLC), is one of the most complex diseases, despite the existence of effective treatments such as chemotherapy and immunotherapy. Since cancer stem cells (CSCs) are responsible for chemo- and radio-resistance, metastasis, and cancer recurrence, finding new therapeutic targets for CSCs is critical. Dinactin is a natural secondary metabolite produced by microorganisms. Recently, dinactin has been revealed as a promising antitumor antibiotic via various mechanisms. However, the evidence relating to cell cycle progression regulation is constrained, and effects on cancer stemness have not been elucidated. Therefore, the aim of this study is to evaluate the new function of dinactin in anti-NSCLC proliferation, focusing on cell cycle progression and cancer stemness properties in Lu99 and A549 cells. Flow cytometry and immunoblotting analyses revealed that 0.1-1 µM of dinactin suppresses cell growth through induction of the G₀/G₁ phase associated with down-regulation of cyclins A, B, and D3, and cdk2 protein expression. The tumor-sphere forming capacity was used to assess the effect of dinactin on the cancer stemness potential in NSCLC cells. At a concentration of 1 nM, dinactin reduced both the number and size of the tumor-spheres. The quantitative RT-PCR analyses indicated that dinactin suppressed sphere formation by significantly reducing expression of CSC markers (i.e., ALDH1A1, Nanog, Oct4, and Sox2) in Lu99 cells. Consequently, dinactin could be a promising strategy for NSCLC therapy targeting CSCs.

LncRNA SNHG5 promotes the proliferation and cancer stem cell-like properties of HCC by regulating UPF1 and Wnt-signaling pathway

The role of long noncoding RNA (lncRNAs) had been demonstrated in different types of cancer, including hepatocellular carcinoma. This study was intended to investigate the role of lncRNA small nucleolar RNA host gene 5 (SNHG5) in HCC proliferation and the liver CSC-like properties. Through functional experiments, we determined that knockdown of SNHG5 repressed HCC cell proliferation and CSC-like properties, while over-expression of SNHG5 promoted cell growth. At the same time, CSC markers (CD44, CD133, and ALDH1) and related transcription factors (OCT4, SOX2, and NANOG) were downregulated when SNHG5 was knocked down. Mechanically, RNA immunoprecipitation (RIP) and RNA pulldown assay showed that SNHG5 regulated the proliferation and CSC-like properties of HCC by binding UPF1. Further investigations showed that expression of critical components of Wnt/β-catenin pathway (β-catenin, TCF4, c-myc, cyclinD1, and c-Jun) were upregulated with depletion of UPF1 in liver CSCs, which were downregulated with depletion of SNHG5. After use of the inhibitor of Wnt/β-catenin pathway, the formation of liver CSCs sphere decreased. Taken together, SNHG5 plays a critical role to promote HCC cell proliferation and cancer stem cell-like properties via UPF1 and Wnt/β-catenin pathway.

Overview of the multifaceted resistances toward EGFR-TKIs and new chemotherapeutic strategies in non-small cell lung cancer

The role of epidermal growth factor receptor (EGFR) in non-small cell lung cancer (NSCLC) has been vastly studied over the last decade. This has led to the rapid development of many generations of EGFR tyrosine kinase inhibitors (EGFR-TKIs). However, patients treated with third-generation TKIs (osimertinib, avitinib and rociletinib) targeting the EGFR T790M mutation have shown emerging resistances and relapses. Therefore, further molecular understanding of NSCLC mutations, bypass signalling, tumour microenvironment and the existence of cancer stem cells to overcome such resistances is warranted. This will pave the way for designing novel and effective chemotherapies to improve patients' overall survival. In this review, we provide an overview of the multifaceted mechanism of resistances towards EGFR-TKIs, as well as the challenges and perspectives that should be addressed in strategising chemotherapeutic treatments to overcome the ever evolving and adaptive nature of NSCLC.

Identification of Prognostic Markers and Potential Therapeutic Targets in Gastric Adenocarcinoma by Machine Learning Based on mRNAsi Index

Background

Cancer stem cells (CSCs), characterized by self-renewal and therapeutic resistance, play important roles in stomach adenocarcinoma (STAD). However, the molecular mechanism of STAD stem cells is still unclear. In this study, our purpose is to explore the expression of stem cell-related genes in STAD.

Methods

The stemness index based on mRNA expression (mRNAsi) was used to analyze STAD cases in The Cancer Genome Atlas (TCGA). Firstly, mRNAsi was used and analyzed by differential expression, survival analysis, clinical stage, and gender in STAD. Then, weighted gene coexpression network analysis (WGCNA) was used to discover the fascinating modules and key genes. Enrichment analysis was carried out to annotate the functions and pathways of key genes. The gene expression comprehensive database (GEO) in STAD was used to verify the expression levels of key genes in all cancers. Protein-protein interaction networks is used to determine the relationships between key genes.

Results

The mRNAsi was obviously upregulated in tumor cases. With the increase of tumor stage and T stage, the mRNAsi score decreased, and the overall survival rate of high score group patients was better. According to the degree of association with mRNAsi, different modules and key genes were screened out. A total of 6,740 differential genes were found, of which 1,147 genes were downregulated and 5,593 genes were upregulated. 19 key genes (BUB1, BUB1B, KIF14, NCAPH, RACGAP, KIF15, CENPF, TPX2, RAD54L, KIF18B, KIF4A, TTK, SGO2, PLK4, ARHGAP11A, XRCC2, Clorf112, NCAPG, and ORC6) were screened due to significant upregulation in STAD. And they had been proven that enriched from the cell cycle Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway, relating to cell proliferation Gene Ontology (GO) terms, as well. Among them, 9 genes have been extensively associated to OS, and 3 genes had been associated to receive chemotherapy resistance. PPI protein network suggests that there is a sturdy correlation between these key genes.

Conclusion

A total of 19 key genes were found to play an essential position in retaining the traits of STAD stem cells. These genes can be used to evaluate the prognosis of STAD patients or become specific therapeutic targets.

Analysis of Circulating Tumor and Cancer Stem Cells Provides New Opportunities in Diagnosis and Treatment of Small Cell Lung Cancer

Current methods for diagnosis and treatment of small cell lung cancer (SCLC) have only a modest efficacy. In this pilot study, we analyzed circulating tumor cells (CTCs) and cancer stem cells (CSCs) in patients with SCLC to search for new diagnostic and prognostic markers and novel approaches to improve the treatment of the disease. In other forms of lung cancer, we showed a heterogeneity of blood CTCs and CSCs populations, as well as changes in other cell populations (ALDH⁺, CD87⁺CD276⁺, and EGF⁺Axl⁺) in smokers. A number of CTCs and CSCs in patients with SCLC have been shown to be resistant to chemotherapy (CT). High cytotoxic activity and resistance to apoptosis of reprogrammed CD3⁺CD8⁺ T-lymphocytes (rTcells) in relation to naive CD3⁺CD8⁺ T-lymphocytes was demonstrated in a smoking patient with SCLC (Patient G) in vitro. The target for rTcells was patient G’s blood CSCs. Reprogramming of CD3⁺CD8⁺ T-lymphocytes was carried out with the MEK1/2 inhibitor and PD-1/PD-L1 pathway blocker nivolumab. The training procedure was performed with a suspension of dead CTCs and CSCs obtained from patient’s G blood. The presented data show a new avenue for personalized SCLC diagnosis and targeted improvement of chemotherapy based on the use of both CTCs and CSCs.

PFKFB3 regulates cancer stemness through the hippo pathway in small cell lung carcinoma

PFKFB3 (6-phosphofructo-2-kinase) is the rate-limiting enzyme of glycolysis and is overexpressed in several human cancers that are associated with poor prognosis. High PFKFB3 expression in cancer stem cells promotes glycolysis and survival in the tumor microenvironment. Inhibition of PFKFB3 by the glycolytic inhibitor PFK158 and by shRNA stable knockdown in small cell lung carcinoma (SCLC) cell lines inhibited glycolysis, proliferation, spheroid formation, and the expression of cancer stem cell markers CD133, Aldh1, CD44, Sox2, and ABCG2. These factors are also associated with chemotherapy resistance. We found that PFK158 treatment and PFKFB3 knockdown enhanced the ABCG2-interacting drugs doxorubicin, etoposide, and 5-fluorouracil in reducing cell viability under conditions of enriched cancer stem cells (CSC). Additionally, PFKFB3 inhibition attenuated the invasion/migration of SCLC cells by downregulating YAP/TAZ signaling while increasing pLATS1 via activation of pMST1 and NF2 and by reducing the mesenchymal protein expression. PFKFB3 knockdown and PFK158 treatment in a H1048 SCLC cancer stem cell-enriched mouse xenograft model showed significant reduction in tumor growth and weight with reduced expression of cancer stem cell markers, ABCG2, and YAP/TAZ. Our findings identify that PFKFB3 is a novel target to regulate cancer stem cells and its associated therapeutic resistance markers YAP/TAZ and ABCG2 in SCLC models.

Cisplatin-Resistant CD44+ Lung Cancer Cells Are Sensitive to Auger Electrons

Cancer stem cells (CSCs) are resistant to conventional therapy and present a major clinical challenge since they are responsible for the relapse of many cancers, including non-small cell lung cancer (NSCLC). Hence, future successful therapy should also eradicate CSCs. Auger electrons have demonstrated promising therapeutic potential and can induce DNA damage while sparing surrounding cells. Here, we sort primary patient-derived NSCLC cells based on their expression of the CSC-marker CD44 and investigate the effects of cisplatin and a thymidine analog (deoxyuridine) labeled with an Auger electron emitter (125I). We show that the CD44+ populations are more resistant to cisplatin than the CD44− populations. Interestingly, incubation with the thymidine analog 5-[125I]iodo-2′-deoxyuridine ([125I]I-UdR) induces equal DNA damage, G2/M cell cycle arrest, and apoptosis in the CD44− and CD44+ populations. Our results suggest that Auger electron emitters can also eradicate resistant lung cancer CD44+ populations.

Immune- and Stemness-Related Genes Revealed by Comprehensive Analysis and Validation for Cancer Immunity and Prognosis and Its Nomogram in Lung Adenocarcinoma

Objective

Lung adenocarcinoma (LUAD) is a familiar lung cancer with a very poor prognosis. This study investigated the immune- and stemness-related genes to develop model related with cancer immunity and prognosis in LUAD.

Method

The Cancer Genome Atlas (TCGA) was utilized for obtaining original transcriptome data and clinical information. Differential expression, prognostic value, and correlation with clinic parameter of mRNA stemness index (mRNAsi) were conducted in LUAD. Significant mRNAsi-related module and hub genes were screened using weighted gene coexpression network analysis (WGCNA). Meanwhile, immune-related differential genes (IRGs) were screened in LUAD. Stem cell index and immune-related differential genes (SC-IRGs) were screened and further developed to construct prognosis-related model and nomogram. Comprehensive analysis of hub genes and subgroups, involving enrichment in the subgroup [gene set enrichment analysis (GSEA)], gene mutation, genetic correlation, gene expression, immune, tumor mutation burden (TMB), and drug sensitivity, used bioinformatics and reverse transcription polymerase chain reaction (RT-PCR) for verification.

Results

Through difference analysis, mRNAsi of LUAD group was markedly higher than that of normal group. Clinical parameters (age, gender, and T staging) were ascertained to be highly relevant to mRNAsi. MEturquoise and MEblue were found to be the most significant modules (including positive and negative correlations) related to mRNAsi via WGCNA. The functions and pathways of the two mRNAsi-related modules were mainly enriched in tumorigenesis, development, and metastasis. Combining stem cell index–related differential genes and immune-related differential genes, 30 prognosis-related SC-IRGs were screened via Cox regression analysis. Then, 16 prognosis-related SC-IRGs were screened to construct a LASSO regression model at last. In addition, the model was successfully validated by using TCGA-LUAD and GSE68465, whereas c-index and the calibration curves were utilized to demonstrate the clinical value of our nomogram. Following the validation of the model, GSEA, immune cell correlation, TMB, clinical relevance, etc., have found significant difference in high- and low-risk groups, and 16-gene expression of the SC-IRG model also was tested by RT-PCR. ADRB2, ANGPTL4, BDNF, CBLC, CX3CR1, and IL3RA were found markedly different expression between the tumor and normal group.

Conclusion

The SC-IRG model and the prognostic nomogram could accurately predict LUAD survival. Our study used mRNAsi combined with immunity that may lay a foundation for the future research studies in LUAD.

Multifunctional Nanoplatforms as a Novel Effective Approach in Photodynamic Therapy and Chemotherapy, to Overcome Multidrug Resistance in Cancer

It is more than sixty years since the era of modern photodynamic therapy (PDT) for cancer began. Enhanced selectivity for malignant cells with a reduced selectivity for non-malignant cells and good biocompatibility along with the limited occurrence of side effects are considered to be the most significant advantages of PDT in comparison with conventional therapeutic approaches, e.g., chemotherapy. The phenomenon of multidrug resistance, which is associated with drug efflux transporters, was originally identified in relation to the application of chemotherapy. Unfortunately, over the last thirty years, numerous papers have shown that many photosensitizers are the substrates of efflux transporters, significantly restricting the effectiveness of PDT. The concept of a dynamic nanoplatform offers a possible solution to minimize the multidrug resistance effect in cells affected by PDT. Indeed, recent findings have shown that the utilization of nanoparticles could significantly enhance the therapeutic efficacy of PDT. Additionally, multifunctional nanoplatforms could induce the synergistic effect of combined treatment regimens, such as PDT with chemotherapy. Moreover, the surface modifications that are associated with nanoparticle functionalization significantly improve the target potential of PDT or chemo-PDT in multidrug resistant and cancer stem cells.

Circ_0020123 promotes NSCLC tumorigenesis via up-regulating KIAA1522 expression through miR-940

Circ_0020123 was highly expressed in NSCLC tissues and cell lines, and knockdown of circ_0020123 abolished cell growth, migration and invasion in vitro and hindered tumor growth in nude mice. Mechanically, circ_0020123 directly targeted miR-940, and KIAA1522 was a target of miR-940. Thereafter, a series of rescue experiments showed that circ_0020123 served its biological functions by miR-940/KIAA1522 axis. In all, circ_0020123 acted as an oncogene to promote the tumorigenesis of NSCLC via miR-940/KIAA1522 axis, suggesting a potential therapeutic target for NSCLC treatment.

Serum Level of CEACAM1 in Patients with Nonsmall Cell Lung Cancer and Its Clinical Significance in Cancer Tissue

Objective

To analyze the expression of CEACAM1 in serum of patients with nonsmall cell lung cancer (NSCLC) and to explore the correlation and clinical significance between the expression of CEACAM1 and pathological parameters of NSCLC tissue.

Methods

A total of 100 patients with NSCLC who underwent tumor resection were screened. Another 100 healthy patients in physical examination department were selected as control group. Venous blood and cancer tissue samples were collected. The expression of CEACAM1, TGF-β, VEGF-A, and IL-8 was detected.

Results

The results of various indicators in the lung cancer group were much higher than those in the healthy group; CEACAM1 was significantly positively correlated with TGF-β expression. The later the clinical stage and the higher the degree of differentiation of cancer tissue specimens, the more the expression of CEACAM1 in serum samples.

Conclusions

The expression level of CEACAM1 in the serum of NSCLC patients is strongly correlated with TGF-β, VEGF-A, and IL-8, indicating that serum CEACAM1 and TGF-β levels can predict the occurrence, progression, and prognosis of lung cancer and provide a target for future targeted therapy of lung cancer.

Genetic Clonality as the Hallmark Driving Evolution of Non-Small Cell Lung Cancer

Simple Summary

Limited knowledge about NSCLC evolution has affected therapeutic strategies for many decades. The application of NGS-based techniques to studies on ITH has provided genetic insight into the contribution of clonality primary seeding, as well as to distant dissemination. To date, multiregional ITH affects accurate diagnosis and treatment decisions and is considered the main hallmark of anticancer therapy failure. Understanding the evolutionary trajectories that drive the metastatic process is critical for improving treatment strategies for this deadly condition. In this review, we discuss how the clonality of genetic alterations influence the seeding of primary and metastatic lesions of NSCLC, highlighting that wide genetic analyses may reveal the phylogenetic lineages of NSCLC evolution.

Abstract

Data indicate that many driver alterations from the primary tumor of non-small cell lung cancer (NSCLC) are predominantly shared across all metastases; however, disseminating cells may also acquire a new genetic landscape across their journey. By comparing the constituent subclonal mutations between pairs of primary and metastatic samples, it is possible to derive the ancestral relationships between tumor clones, rather than between tumor samples. Current treatment strategies mostly rely on the theory that metastases are genetically similar to the primary lesions from which they arise. However, intratumor heterogeneity (ITH) affects accurate diagnosis and treatment decisions and it is considered the main hallmark of anticancer therapy failure. Understanding the genetic changes that drive the metastatic process is critical for improving the treatment strategies of this deadly condition. Application of next generation sequencing (NGS) techniques has already created knowledge about tumorigenesis and cancer evolution; however, further NGS implementation may also allow to reconstruct phylogenetic clonal lineages and clonal expansion. In this review, we discuss how the clonality of genetic alterations influence the seeding of primary and metastatic lesions of NSCLC. We highlight that wide genetic analyses may reveal the phylogenetic trajectories of NSCLC evolution, and may pave the way to better management of follow-up and treatment.

Impact of Cancer Stem Cells and Cancer Stem Cell-Driven Drug Resiliency in Lung Tumor: Options in Sight

Causing a high mortality rate worldwide, lung cancer remains an incurable malignancy resistant to conventional therapy. Despite the discovery of specific molecular targets and new treatment strategies, there remains a pressing need to develop more efficient therapy to further improve the management of this disease. Cancer stem cells (CSCs) are considered the root of sustained tumor growth. This consensus corroborates the CSC model asserting that a distinct subpopulation of malignant cells within a tumor drives and maintains tumor progression with high heterogeneity. Besides being highly tumorigenic, CSCs are highly refractory to standard drugs; therefore, cancer treatment should be focused on eliminating these cells. Herein, we present the current knowledge of the existence of CSCs, CSC-associated mechanisms of chemoresistance, the ability of CSCs to evade immune surveillance, and potential CSC inhibitors in lung cancer, to provide a wider insight to drive a more efficient elimination of this pro-oncogenic and treatment-resistant cell fraction.

Dictamnine, a novel c-Met inhibitor, suppresses the proliferation of lung cancer cells by downregulating the PI3K/AKT/mTOR and MAPK signaling pathways

Dictamnine (Dic), a naturally occurring small-molecule furoquinoline alkaloid isolated from the root bark of Dictamnus dasycarpus Turcz., is reported to display anticancer properties. However, little is known about the direct target proteins and anticancer mechanisms of Dic. In the current study, Dic was found to suppress the growth of lung cancer cells in vitro and in vivo, and to attenuate the activation of PI3K/AKT/mTOR and mitogen-activated protein kinase (MAPK) signaling pathways by inhibiting the phosphorylation and activation of receptor tyrosine kinase c-Met. Moreover, the binding of Dic to c-Met was confirmed by using cellular thermal shift assay (CETSA) and drug affinity responsive target stability (DARTS) assay. Among all cancer cell lines tested, Dic inhibited the proliferation of c-Met-dependent EBC-1 cells with the greatest potency (IC50 = 2.811 μM). Notably, Dic was shown to synergistically improve the chemo-sensitivity of epidermal growth factor receptor-tyrosine kinase inhibitor (EGFR-TKI)-resistant lung cancer cells to gefitinib and osimertinib. These results suggest that Dic is a c-Met inhibitor that can serve as a potential therapeutic agent in the treatment of lung cancer, especially against EGFR TKI-resistant and c-Met-dependent lung cancer.

Potential Role of GST-π in Lung Cancer Stem Cell Cisplatin Resistance

Background

Cancer stem cells (CSCs) are responsible for tumorigenesis, chemoresistance, and metastasis. Chemoresistance is a major challenge in the management of lung cancer. Glutathione-sulphur-transferase-π (GST-π) plays an important role in the origin and development of various types of cancer by regulating the cellular redox balance. Recent investigations have demonstrated that GST-π is associated with the chemoresistance of lung CSCs (LCSCs). However, the mechanism of GST-π in lung cancer, particularly in LCSCs, remains unclear. The present study is aimed at exploring the potential role of GST-π in stemness and cisplatin (DDP) resistance of LCSCs. Materials and methods. In the present study, lung cancer cell spheres were established using the A549 cell line, which according to our previous research, was confirmed to exhibit characteristics of stem cells. Next, GST-π protein expression, apoptosis percentage, and intracellular reactive oxygen species (ROS) concentration in A549 adherent cells and A549 cell spheres were analyzed by western blotting and flow cytometry, respectively. Finally, DDP resistance, ROS concentration, and GST-π expression in LCSCs were analyzed following the interference with GST-π using DL-buthionine-(S,R)-sulphoximine and N-acetylcysteine.

Results

The results revealed that GST-π was highly expressed in A549 cell spheres compared with A549 adherent cells and was associated with a decreased intracellular ROS concentration (both P < 0.05). Regulating GST-π protein expression could alter DDP resistance of LCSCs by influencing ROS.

Conclusion

These results suggested that GST-π may be important for LCSC drug resistance by downregulating ROS levels. These findings may contribute to the development of new adjuvant therapeutic strategies for lung cancer.

Primary Lung Cancer Organoids for Personalized Medicine-Are They Ready for Clinical Use?

Simple Summary

Identification of novel therapeutic strategies for the treatment of non-small cell lung cancer (NSCLC) remains an urgent need in the area of lung cancer research. Traditional in vitro cell culture systems form one of the corner stones of cancer research. However, the growth of cancer cells in a two-dimensional pattern on a plastic dish in artificial conditions is not ideal, as the growth pattern significantly differs from that of a complex tumor in a patient. Hence, in recent years, efforts have been undertaken to generate more complex three-dimensional in vitro models, so-called organoid or tumoroid models, that more closely resemble the growth pattern and tumor heterogeneity observed in a patient. In this review, we summarize the efforts thus far undertaken in the area of NSCLC organoid development.

Abstract

Despite many developments in recent years, non-small cell lung cancer (NSCLC) remains the leading cause of cancer-related death worldwide. Therefore, additional research, aiming to further elucidate the underlying molecular mechanisms of malignant transformation and development of therapy resistance, as well as the identification of additional novel therapeutic avenues, is crucial. For this purpose, reliable in vitro models are indispensable, as they allow for quick identification of suspected oncogenic drivers or evaluation of novel therapeutic strategies in a timely and cost-effective fashion. However, standard two-dimensional cell culture systems, the most frequently used in vitro model, are usually not truly representative of the situation in a patient as these models lack the tumor heterogeneity, the surrounding tumor microenvironment and the three-dimensional complexity of a tumor in vitro. For this reason, 3D cell culture systems, in particular organoids generated from normal non-malignant cells or tumor cell-based organoids (tumoroids), have in recent years gained much attention as alternative in vitro model systems that more closely resemble the actual primary tumor. In this review, we provide an overview of the available literature in the field of NSCLC organoids, which might still be in its infancy, but is gaining momentum.

WITHDRAWN: FOXC1 modulates stem-like cell properties and chemoresistance through hedgehog and EMT signaling in gastric adenocarcinoma

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Aluminium (III) phthalocyanine chloride tetrasulphonate is an effective photosensitizer for the eradication of lung cancer stem cells

Cancer stem cells (CSCs) are considered to contribute to the recurrence of lung cancer due to their stem-like nature and the involvement of genetic markers associated with drug efflux, regeneration and metastases. Photodynamic therapy (PDT) is a cost-effective and non-invasive therapeutic application that can act as an alternative therapy for lung cancer when considering CSC involvement. Stem-like cells derived from the A549 lung cancer cell line, positive for CD133, CD56 and CD44 antigen markers, were characterized, intracellular localization of aluminium (III) phthalocyanine chloride tetrasulphonate (AlPcS₄Cl) determined and its anti-cancer PDT effects were evaluated. Results confirmed that isolated cells were stem cell-like and subcellular localization of AlPcS₄Cl in integral organelles involved in cell homeostasis supported the destruction of CSC. AlPcS₄Cl's effectivity was demonstrated with CSC eradication showing a significant increase in cytotoxicity and cell death via apoptosis, caused by a decrease in mitochondrial membrane potential. PDT could serve as a palliative treatment for lung cancer and improve prognosis by elimination of lung CSCs.

Triple Negative Breast Cancer: A Mountain Yet to Be Scaled Despite the Triumphs

Metastatic progression and tumor recurrence pertaining to TNBC are certainly the leading cause of breast cancer-related mortality; however, the mechanisms underlying TNBC chemoresistance, metastasis, and tumor relapse remain somewhat ambiguous. TNBCs show 77% of the overall 4-year survival rate compared to other breast cancer subtypes (82.7 to 92.5%). TNBC is the most aggressive subtype of breast cancer, with chemotherapy being the major approved treatment strategy. Activation of ABC transporters and DNA damage response genes alongside an enrichment of cancer stem cells and metabolic reprogramming upon chemotherapy contribute to the selection of chemoresistant cells, majorly responsible for the failure of anti-chemotherapeutic regime. These selected chemoresistant cells further lead to distant metastasis and tumor relapse. The present review discusses the approved standard of care and targetable molecular mechanisms in chemoresistance and provides a comprehensive update regarding the recent advances in TNBC management.

LINC01224/ZNF91 Promote Stem Cell-Like Properties and Drive Radioresistance in Non-Small Cell Lung Cancer

Background

Radioresistance is the main reason for the failure of radiotherapy in non-small-cell lung cancer (NSCLC); however, the molecular mechanism of radioresistance is still unclear.

Methods

An RNA-Seq assay was used to screen differentially expressed long non-coding RNAs (lncRNAs) and genes in irradiation-resistant NSCLC cells. RT-PCR and Western blotting assays were performed to analyze the expressions of lncRNAs and genes. The chromosome conformation capture (3C) assay was performed to measure chromatin interactions. Cell cytotoxicity, cell apoptosis, sphere formation and Transwell assays were performed to assess cellular function.

Results

In this study, it was found that LINC01224 increased during the induction of radioresistance in NSCLC cells. LINC01224 was located within the enhancer of ZNF91, and LINC01224 could affect the transcription of ZNF91 by regulating the long-range interactions between the ZNF91 enhancer and promoter. Moreover, upregulation of LINC01224 and ZNF91 could promote irradiation resistance by regulating the stem cell-like properties of NSCLC cells. In addition, high expression levels of LINC01224 and ZNF91 in tissue samples were associated with radioresistance in NSCLC patients.

Conclusion

Our findings demonstrated that LINC01224/ZNF91 drove radioresistance regulation by promoting the stem cell-like properties in NSCLC.

Sonlicromanol's active metabolite KH176m normalizes prostate cancer stem cell mPGES-1 overexpression and inhibits cancer spheroid growth

Aggressiveness of cancers, like prostate cancer, has been found to be associated with elevated expression of the microsomal prostaglandin E synthase-1 (mPGES-1). Here, we investigated whether KH176m (the active metabolite of sonlicromanol), a recently discovered selective mPGES-1 inhibitor, could affect prostate cancer cells-derived spheroid growth. We demonstrated that KH176m suppressed mPGES-1 expression and growth of DU145 (high mPGES-1 expression)-derived spheroids, while it had no effect on the LNCaP cell line, which has low mPGES-1 expression. By addition of exogenous PGE₂, we found that the effect of KH176m on mPGES-1 expression and spheroid growth is due to the inhibition of a PGE₂-driven positive feedback control-loop of mPGES-1 transcriptional regulation. Cancer stem cells (CSCs) are a subset of cancer cells exhibiting the ability of self-renewal, plasticity, and initiating and maintaining tumor growth. Our data shows that mPGES-1 is specifically expressed in this CSCs subpopulation (CD44⁺CD24^-). KH176m inhibited the expression of mPGES-1 and reduced the growth of spheroids derived from the CSC. Based on the results obtained we propose selective mPGES-1 targeting by the sonlicromanol metabolite KH176m as a potential novel treatment approach for cancer patients with high mPGES-1 expression.

Lin28A promotes the proliferation and stemness of lung cancer cells via the activation of mitogen-activated protein kinase pathway dependent on microRNA let-7c

Background

Among patients with lung cancer, metastatic and relapsed cases account for the largest proportion of disease-associated deaths. Tumor metastasis and relapse are believed to originate from cancer stem cells (CSCs), which have the capacity to be highly proliferative and invasive. In our previous studies, we established a conditional basement membrane extract-based (BME-based) 3-dimensional (3D) culture system to mimic the tumor growth environment in vivo and further amplified lung cancer stem cells (LCSCs) in our system. However, the molecular mechanisms of LCSC amplification and development in our 3D culture system have not been fully uncovered.

Method

We established the conditional 3D culture system to amplify LCSCs in other lung cancer cell lines, followed by examining the expression of Lin28A and let-7 microRNAs in them. We also explored the expression of Lin28A and let-7 microRNAs in LCSCs from clinical lung cancer tissue samples and even analyzed the correlation of Lin28A/let-7c and patients’ survival outcomes. We further constructed A549 cells either knockdown of Lin28A or overexpression of let-7c, followed by investigating stemness marker gene expression, and stemness phenotypes including mammosphere culture, cell migration and invasion in vitro, as well as tumorigenicity in vivo.

Results

Here, we observed that Lin28A/let-7c was dysregulated in LCSCs in both the 3D culture system and lung cancer tissues. Further, the abnormal expression of Lin28A/let-7c was correlated with poor survival outcomes. Via the construction of A549 cells with let-7c over-expression, we found that let-7c inhibited the maintenance of LCSC properties, while the results of Lin28A knockdown showed that Lin28A played a critical role in the enrichment and proliferation of LCSCs via mitogen-activated protein kinase (MAPK) signaling pathway. Importantly, we found that LCSCs with knockdown of Lin28A or over-expression of let-7c exhibited inhibited carcinogenesis and disrupted expansion in vivo.

Conclusions

Our study uncovered the functions and mechanisms of the Lin28A/let-7c/MAPK signaling pathway in promoting the proliferation and cancer stemness of LCSCs, which might be a potential therapeutic target for reducing and even eliminating LCSCs in the future.

Understanding Lung Carcinogenesis from a Morphostatic Perspective: Prevention and Therapeutic Potential of Phytochemicals for Targeting Cancer Stem Cells

Lung cancer is still one of the deadliest cancers, with over two million incidences annually. Prevention is regarded as the most efficient way to reduce both the incidence and death figures. Nevertheless, treatment should still be improved, particularly in addressing therapeutic resistance due to cancer stem cells—the assumed drivers of tumor initiation and progression. Phytochemicals in plant-based diets are thought to contribute substantially to lung cancer prevention and may be efficacious for targeting lung cancer stem cells. In this review, we collect recent literature on lung homeostasis, carcinogenesis, and phytochemicals studied in lung cancers. We provide a comprehensive overview of how normal lung tissue operates and relate it with lung carcinogenesis to redefine better targets for lung cancer stem cells. Nine well-studied phytochemical compounds, namely curcumin, resveratrol, quercetin, epigallocatechin-3-gallate, luteolin, sulforaphane, berberine, genistein, and capsaicin, are discussed in terms of their chemopreventive and anticancer mechanisms in lung cancer and potential use in the clinic. How the use of phytochemicals can be improved by structural manipulations, targeted delivery, concentration adjustments, and combinatorial treatments is also highlighted. We propose that lung carcinomas should be treated differently based on their respective cellular origins. Targeting quiescence-inducing, inflammation-dampening, or reactive oxygen species-balancing pathways appears particularly interesting.

Apatinib suppresses lung cancer stem-like cells by complex interplay between β-catenin signaling and mitochondrial ROS accumulation

The abnormal activation of Wnt/β-catenin signaling plays a critical role in the development of lung cancer, which is also important in the generation and maintenance of lung cancer stem cell (CSC). CSCs have unique capabilities to resist anticancer therapy, seed recurrent tumors, and disseminate to and colonize distant tissues. Apatinib, a small-molecule VEGFR2-tyrosine kinase inhibitor, shows highly efficient antitumor activity in heavily treated, chemoresistant, and metastatic lung cancer. We speculated that inhibition of Wnt/β-catenin signaling and targeting lung CSCs could be one of the anti-tumor mechanisms of apatinib. In the present study we demonstrated that apatinib repressed lung CSC-like traits by hindering sphere formation ability, lung CSC-related marker expression and decreasing chemoresistance derived stemness. Mechanistically, apatinib exerted its anti-CSC effects by inhibiting β-catenin and its downstream targets. Moreover, apatinib induced the production of reactive oxyen species (ROS), which participated in the inhibitory effects of apatinib on lung CSCs. It was found that β-catenin regulated apatinib-induced production of ROS. Inhibition or promotion of ROS production with N-acetyl-L-cysteine or H₂O₂ not only upregulated or downregulated β-catenin expression, but also prevented or promoted DNA damage, rescued or impeded sphere formation, respectively. Collectively, our findings reveal that apatinib directly inhibits β-catenin signaling and promotes ROS generation to suppress lung CSC-like characteristics. A clearer understanding of the anti-cancer mechanisms of apatinib is required for its better application in combating advanced and refractory/recurrent lung cancer when combined with conventional chemotherapy.

Paclitaxel-Based Chemotherapy Targeting Cancer Stem Cells from Mono- to Combination Therapy

Paclitaxel (PTX) is a chemotherapeutical agent commonly used to treat several kinds of cancer. PTX is known as a microtubule-targeting agent with a primary molecular mechanism that disrupts the dynamics of microtubules and induces mitotic arrest and cell death. Simultaneously, other mechanisms have been evaluated in many studies. Since the anticancer activity of PTX was discovered, it has been used to treat many cancer patients and has become one of the most extensively used anticancer drugs. Regrettably, the resistance of cancer to PTX is considered an extensive obstacle in clinical applications and is one of the major causes of death correlated with treatment failure. Therefore, the combination of PTX with other drugs could lead to efficient therapeutic strategies. Here, we summarize the mechanisms of PTX, and the current studies focusing on PTX and review promising combinations.

Reck-Notch1 Signaling Mediates miR-221/222 Regulation of Lung Cancer Stem Cells in NSCLC

Cancer stem cells (CSCs) contribute to the cancer initiation, metastasis and drug resistance in non-small cell lung cancer (NSCLC). Herein, we identified a miR-221/222 cluster as a novel regulator of CSCs in NSCLC. Targeted overexpression or knockdown of miR-221/222 in NSCLC cells revealed the essential roles of miR-221/222 in regulation of lung cancer cell proliferation, mammosphere formation, subpopulation of CD133⁺ CSCs and the expression of stemness genes including OCT4, NANOG and h-TERT. The in vivo animal study showed that overexpression of miR-221/222 significantly enhanced the capacity of lung cancer cells to develop tumor and grow faster, indicating the importance of miR-221/222 in tumorigenesis and tumor growth. Mechanistically, Reck was found to be a key direct target gene of miR-221/222 in NSCLC. Overexpression of miR-221/222 significantly suppressed Reck expression, activated Notch1 signaling and increased the level of NICD. As an activated form of Notch1, NICD leads to enhanced stemness in NSCLC cells. In addition, knockdown of Reck by siRNA not only mimicked miR-221/222 effects, but also demonstrated involvement of Reck in the miR-221/222-induced activation of Notch1 signaling, verifying the essential roles of the miR-221/222-Reck-Notch1 axis in regulating stemness of NSCLC cells. These findings uncover a novel mechanism by which lung CSCs are significantly manipulated by miR-221/222, and provide a potential therapeutic target for the treatment of NSCLC.

Discovering and Characterizing of Survivin Dominant Negative Mutants With Stronger Pro-apoptotic Activity on Cancer Cells and CSCs

Survivin as a member of the inhibitor of apoptosis proteins (IAPs) family is undetectable in normal cells, but highly expressed in cancer cells and cancer stem cells (CSCs) which makes it an attractive target in cancer therapy. Survivin dominant negative mutants have been reported as competitive inhibitors of endogenous survivin protein in cancer cells. However, there is a lack of systematic comparative studies on which mutants have stronger effect on promoting apoptosis in cancer cells, which will hinder the development of novel anti-cancer drugs. Here, based on the previous study of survivin and its analysis of the relationship between structure and function, we designed and constructed a series of different amino acid mutants from survivin (TmSm34, TmSm48, TmSm84, TmSm34/48, TmSm34/84, and TmSm34/48/84) fused cell-permeable peptide TATm at the N-terminus, and a dominant negative mutant TmSm34/84 with stronger pro-apoptotic activity was selected and evaluated systematically in vitro. The double-site mutant of survivin (TmSm34/84) showed more robust pro-apoptotic activity against A549 cells than others, and could reverse the resistance of A549 CSCs to adriamycin (ADM) (reversal index up to 7.01) by decreasing the expression levels of survivin, P-gp, and Bcl-2 while increasing cleaved caspase-3 in CSCs. This study indicated the selected survivin dominant negative mutant TmSm34/84 is promising to be an excellent candidate for recombinant anti-cancer protein by promoting apoptosis of cancer cells and their stem cells and sensitizing chemotherapeutic drugs.

Characteristics of the PI3K/AKT and MAPK/ERK pathways involved in the maintenance of self-renewal in lung cancer stem-like cells

Lung cancer is the leading cause of cancer-related mortality worldwide due to its early asymptomatic and late metastasis. While cancer stem cells (CSCs) may play a vital role in oncogenesis and development of lung cancer, mechanisms underlying CSCs self-renewal remain less clear. In the present study, we constructed a clinically relevant CSCs enrichment recognition model and evaluated the potential functions of phosphatidylinositol 3-kinase (PI3K)/AKT pathway (PI3K/AKT) and mitogen-activated protein kinases/extracellular signal-regulated kinase (MAPK/ERK) pathways in lung cancer via bioinformatic analysis, providing the basis for in depth mechanistic inquisition. Experimentally, we confirmed that PI3K/AKT pathway predominantly promotes proliferation through anti-apoptosis in lung adenocarcinoma cells, while MAPK/ERK pathway has an overwhelming superiority in regulating the proliferation in lung CSCs. Further, utilizing stemness score model, LLC-Symmetric Division (LLC-SD) cells and mouse orthotopic lung transplantation model, we elucidated an intricate cross-talk between the oncogenic pathway and the stem cell reprograming pathway that impact stem cell characteristics as well as cancer biology features of lung CSCs both in vitro and in vivo. In summary, our findings uncovered a new insight that PI3K/AKT and MAPK/ERK pathways as oncogenic signaling pathway and/or stem cell signaling pathway act distinctively and synergistically to regulate lung CSCs self-renewal.

Human ES and iPS cells display less drug resistance than differentiated cells, and naïve-state induction further decreases drug resistance

Pluripotent stem cells (PSCs) possess unique characteristics that distinguish them from other cell types. Human embryonic stem (ES) cells are recently gaining attention as a powerful tool for human toxicity assessment without the use of experimental animals, and an embryonic stem cell test (EST) was introduced for this purpose. However, human PSCs have not been thoroughly investigated in terms of drug resistance or compared with other cell types or cell states, such as naïve state, to date. Aiming to close this gap in research knowledge, we assessed and compared several human PSC lines for their resistance to drug exposure. Firstly, we report that RIKEN-2A human induced pluripotent stem (iPS) cells possessed approximately the same sensitivity to selected drugs as KhES-3 human ES cells. Secondly, both ES and iPS cells were several times less resistant to drug exposure than other non-pluripotent cell types. Finally, we showed that iPS cells subjected to naïve-state induction procedures exhibited a sharp increase in drug sensitivity. Upon passage of these naïve-like cells in non-naïve PSC culture medium, their sensitivity to drug exposure decreased. We thus revealed differences in sensitivity to drug exposure among different types or states of PSCs and, importantly, indicated that naïve-state induction could increase this sensitivity.

EZH2-mediated epigenetic suppression of SH3BGRL potently inhibits lung cancer progression

Lung cancer is the leading cause of cancer-related deaths worldwide. Lung cancer stem cells (CSCs) are a small population of cancer cells with self-renewal, therapeutic resistance, and tumor relapse capability. Yet the molecular mechanisms underlying lung CSCs self-renewal remain largely unknown. Here, we report that SH3BGRL were down-regulated in lung cancer tissues comparing with normal lung tissues and SH3BGRL low expression was correlated with the poor clinical outcomes of patients with lung cancer. Moreover, SH3BGRL was also weakly expressed in lung CSCs compared with its corresponding lung cancer cells. We first characterize that EZH2 directly binds to SH3BGRL promoter and transcriptional represses SH3BGRL expression in epigenetic level. Functionally, overexpression of SH3BGRL potently suppresses Lung CSCs self-renewal in vitro. The gain of function study reveals that SH3BGRL acts as a novel tumor suppressor via inhibiting lung cancer cell proliferation and migration as well as Lung CSCs self-renewal in vitro. Collectively, our work demonstrates that SH3BGRL hold potential as a favorable prognostic marker and therapeutic target for patients with lung cancer in future.

Cancer Stemness-Based Prognostic Immune-Related Gene Signatures in Lung Adenocarcinoma and Lung Squamous Cell Carcinoma

BACKGROUND

Cancer stem cells (CSCs) refer to cells with self-renewal capability in tumors. CSCs play important roles in proliferation, metastasis, recurrence, and tumor heterogeneity. This study aimed to identify immune-related gene-prognostic models based on stemness index (mRNAsi) in lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC), respectively.

METHODS

X-tile software was used to determine the best cutoff value of survival data in LUAD and LUSC based on mRNAsi. Tumor purity and the scores of infiltrating stromal and immune cells in lung cancer tissues were predicted with ESTIMATE R package. Differentially expressed immune-related genes (DEIRGs) between higher- and lower-mRNAsi subtypes were used to construct prognostic models.

RESULTS

mRNAsi was negatively associated with StromalScore, ImmuneScore, and ESTIMATEScore, and was positively associated with tumor purity. LUAD and LUSC samples were divided into higher- and lower-mRNAsi groups with X-title software. The distribution of immune cells was significantly different between higher- and lower-mRNAsi groups in LUAD and LUSC. DEIRGs between those two groups in LUAD and LUSC were enriched in multiple cancer- or immune-related pathways. The network between transcriptional factors (TFs) and DEIRGs revealed potential mechanisms of DEIRGs in LUAD and LUSC. The eight-gene-signature prognostic model (ANGPTL5, CD1B, CD1E, CNTFR, CTSG, EDN3, IL12B, and IL2)-based high- and low-risk groups were significantly related to overall survival (OS), tumor microenvironment (TME) immune cells, and clinical characteristics in LUAD. The five-gene-signature prognostic model (CCL1, KLRC3, KLRC4, CCL23, and KLRC1)-based high- and low-risk groups were significantly related to OS, TME immune cells, and clinical characteristics in LUSC. These two prognostic models were tested as good ones with principal components analysis (PCA) and univariate and multivariate analyses. Tumor T stage, pathological stage, or metastasis status were significantly correlated with DEIRGs contained in prognostic models of LUAD and LUSC.

CONCLUSION

Cancer stemness was not only an important biological process in cancer progression but also might affect TME immune cell infiltration in LUAD and LUSC. The mRNAsi-related immune genes could be potential biomarkers of LUAD and LUSC. Evaluation of integrative characterization of multiple immune-related genes and pathways could help to understand the association between cancer stemness and tumor microenvironment in lung cancer.

CBL0137 increases the targeting efficacy of Rovalpituzumab tesirine against tumour-initiating cells in small cell lung cancer

Small cell lung cancer (SCLC) is characterised by high relapse rates. Tumour-initiating cells (TICs) are responsible for drug resistance and recurrence of cancer. Rovalpituzumab tesirine (Rova-T), a potent humanised antibody–drug conjugate, selectively targets delta-like protein 3, which is highly expressed in SCLC TICs. The experimental drug CBL0137 (CBL) inhibits the histone chaperone FACT (facilitates chromatin transcription), which is required for the expression of transcription factors that are essential for TIC maintenance. Rova-T and CBL each target SCLC TICs as single agents. However, acquired or intrinsic resistance to single agents is a major problem in cancer. Therefore, we investigated the potential effect of combining Rova-T and CBL in SCLC to eradicate TICs more effectively. Our preclinical studies report a novel and highly translatable therapeutic strategy of dual targeting TICs using Rova-T in combination with CBL to potentially increase survival of SCLC patients.

Circulating tumor cell characterization of lung cancer brain metastases in the cerebrospinal fluid through single-cell transcriptome analysis

BACKGROUND

Brain metastases explain the majority of mortality associated with lung cancer, which is the leading cause of cancer death. Cytology analysis of the cerebrospinal fluid (CSF) remains the diagnostic gold standard, however, the circulating tumor cells (CTCs) in CSF (CSF-CTCs) are not well defined at the molecular and transcriptome levels.

METHODS

We established an effective CSF-CTCs collection procedure and isolated individual CSF cells from five lung adenocarcinoma leptomeningeal metastases (LUAD-LM) patients and three controls. Three thousand seven hundred ninety-two single-cell transcriptomes were sequenced, and single-cell RNA sequencing (scRNA-seq) gene expression analysis was used to perform a comprehensive characterization of CSF cells.

RESULTS

Through clustering and expression analysis, we defined CSF-CTCs at the transcriptome level based on epithelial markers, proliferation markers, and genes with lung origin. The metastatic-CTC signature genes are enriched for metabolic pathway and cell adhesion molecule categories, which are crucial for the survival and metastases of tumor cells. We discovered substantial heterogeneity in patient CSF-CTCs. We quantified the degree of heterogeneity and found significantly greater among-patient heterogeneity compared to among-cell heterogeneity within a patient. This observation could be explained by spatial heterogeneity of metastatic sites, cell-cycle gene, and cancer-testis antigen (CTA) expression profiles as well as the proportion of CTCs displaying mesenchymal and cancer stem cell properties. In addition, our CSF-CTCs transcriptome profiling allowed us to determine the biomarkers during the progression of an LM patient with cancer of unknown primary site (CUP).

CONCLUSIONS

Our results will provide candidate genes for an RNA-based digital detection of CSF-CTCs from LUAD-LM and CUP-LM cases, and shed light on the therapy and mechanism of LUAD-LM.

Cancer Stem Cell Markers in Relation to Patient Survival Outcomes: Lessons for Integrative Diagnostics and Next-Generation Anticancer Drug Development

Solid tumors display a complex biology that requires a multipronged treatment strategy. Most anticancer interventions, including chemotherapy, are currently unable to prevent treatment resistance and relapse. In general, therapeutics target cancer cells and overlook the tumor microenvironment (TME) and the presence of cancer stem cells (CSCs) with self-renewal and tumorigenic abilities. CSCs have been postulated to play key roles in tumor initiation, progression, therapy resistance, and metastasis. Hence, CSC markers have been suggested as diagnostics to forecast cancer prognosis as well as molecular targets for new-generation cancer treatments, especially in resistant disease. We report here original findings on expression and prognostic significance of CSC markers in several cancers. We examined and compared the transcriptional expression of CSC markers (ABCB1, ABCG2, ALDH1A1, CD24, CD44, CD90, CD133, CXCR4, EPCAM, ICAM1, and NES) in tumor tissues versus the adjacent normal tissues using publicly available databases, The Cancer Genome Atlas and Gene Expression Profiling Interactive Analysis. We found that CSC transcriptional markers were, to a large extent, expressed in higher abundance in solid tumors such as colon, lung, pancreatic, and esophageal cancers. On the other hand, no CSC marker in our analysis was expressed in the same pattern in all cancers, while individual CSC marker expression, alone, was not significantly associated with overall patient survival. Innovation in next-generation cancer therapeutics and diagnostics ought to combine CSC markers as well as integrative diagnostics that pool knowledge from CSCs and other TME components and cancer cells.