Cigarette smoke stimulates the stemness of renal cancer stem cells via Sonic Hedgehog pathway

ΔNp63α promotes cigarette smoke-induced renal cancer stem cell activity via the Sonic Hedgehog pathway

Cigarette smoke (CS) has been generally recognized as a chief carcinogenic factor in renal cell carcinoma (RCC). The stimulative effect of CS on renal cancer stem cells (RCSCs) has been described previously. The Sonic Hedgehog (SHH) pathway plays an essential role in self-renewal, cell growth, drug resistance, metastasis, and recurrence of cancer stem cells (CSCs). Renal cancer-related gene ΔNp63α is highly expressed in renal epithelial tissues and contributes to the RCSCs characteristics of tumors. The aim of this study was to elucidate the role of ΔNp63α and the SHH pathway on the activity of RCSCs induced by CS through a series of in vivo and in vitro studies. It was shown that in renal cancer tissues, ΔNp63α and RCSCs markers in smokers are expressed higher than that in non-smokers. RCSCs were effectively enriched by tumor sphere formation assay. Besides, CS increased the expression of RCSCs markers and the capability of sphere-forming in vitro and in vivo. Moreover, the SHH pathway was activated, and the specialized inhibitor alleviated the promotion of CS on RCSCs. ΔNp63α activated the SHH pathway and promoted CS-induced enhancement of RCSCs activity. These findings indicate that ΔNp63α positively regulates the activity of CS-induced RCSCs via the SHH pathway.

Common immunological and prognostic features of lung and bladder cancer via smoking-related genes: PRR11 gene as potential immunotherapeutic target

Smoking is a well-known risk factor for non-small-cell lung cancer (NSCLC) and bladder urothelial carcinoma (BLCA). Despite this, there has been no investigation into a prognostic marker based on smoking-related genes that could universally predict prognosis in these cancers and correlate with immune checkpoint therapy. This study aimed to identify smoking-related differential genes in NSCLC and BLCA, analyse their roles in patient prognosis and immune checkpoint therapy through subgroup analyses, and shed light on PRR11 as a crucial prognostic gene in both cancers. By examining PRR11 co-expressed genes, a prognostic model was constructed and its impact on immunotherapy for NSCLC and BLCA was evaluated. Molecular docking and tissue microarray analyses were conducted to explore the correlation between PRR11 and its reciprocal gene SPDL1. Additionally, miRNAs associated with PRR11 were analysed. The study confirmed a strong link between smoking-related genes, prognosis, and immune checkpoint therapy in NSCLC and BLCA. PRR11 was identified as a key smoking-associated gene that influences the efficacy of immune checkpoint therapy by modulating the stemness of these cancers. A prognostic model based on PRR11 co-expressed genes in BLCA was established and its prognostic value was validated in NSCLC. Furthermore, it was found that PRR11 regulates PDL1 via SPDL1, impacting immunotherapeutic efficacy in both cancers. The involvement of hsa-miR-200b-3p in the regulation of SPDL1 expression by PRR11 was also highlighted. Overall, the study elucidates that PRR11 modulates patient immunotherapy by influencing PDL1 expression through its interaction with SPDL1, with potential upstream regulation by hsa-miR-200b-3p.

BIRC6 Modulates the Protein Stability of Axin to Regulate the Growth, Stemness, and Resistance of Renal Cancer Cells via the β-Catenin Pathway

The mechanism underlying the development of renal cell carcinoma (RCC) remains unclear, and effective prevention and therapeutic measures are lacking. BIRC6, a protein inhibitor of apoptosis, has attracted great interest. Our data indicated that overexpression of BIRC6 elevated cell growth, colony formation, migration, and invasion of cultured RCC cells, while siRNA knockdown of BIRC6 suppressed these processes. Additionally, BIRC6 was highly expressed in RCC clinical samples along with a downregulated level of Axin. Immunoprecipitation assays found that BIRC6 interacted with Axin and the two proteins colocalized within the cytoplasm of RCC cells. Overexpression of BIRC6 promoted the ubiquitination modification of Axin, while genetic knockdown of BIRC6 suppressed it. Furthermore, overexpression of BIRC6 significantly promoted the turnover of Axin, suggesting BIRC6's inhibitory effect on Axin protein stability. BIRC6 was also upregulated in cancer stem-like cells of RCC and increased the drug resistance of RCC cells against sunitinib. Western blotting assays showed that the overexpression of BIRC6 upregulated CXCR4 protein expression and activated the β-catenin pathway. Two cell lines were then constructed with BIRC6 overexpressed by lentiviruses. Pharmacological administration of a Wnt/β-catenin inhibitor, XAV-939, or genetic knockdown of β-catenin inhibited cell growth, tumor sphere formation, colony formation, migration, and invasion of BIRC6-overexpressed cells. In vivo administration of XAV-939 markedly suppressed the tumorigenesis of BIRC6-overexpressed RCC cells in nude mice. In conclusion, we propose that BIRC6 activates the β-catenin signaling pathway via mediating the ubiquitination and degradation of Axin, promoting the growth, stemness, and drug resistance of RCC cells. This project aims to elucidate the role of BIRC6 as a potential therapeutic target and provide new insights into the clinical treatment of RCC.

Diallyl Trisulfide Suppresses the Renal Cancer Stem-like Cell Properties via Nanog

Cancer stem-like cells (CSCs), which play an important role in tumor initiation and progression, have been identified in many cancers. Diallyl trisulfide (DATS) is an organosulfur compound extracted from garlic with anticancer activities. Nanog is a transcription factor responsible for maintaining the stemness of CSCs, but its role in the DATS-induced attenuation of renal CSC properties is unknown. In this study, renal CSCs were enriched from human renal cancer cell lines 786-O and ACHN cultured in a serum-free medium (SFM). The properties of CSCs were analyzed by evaluating the ability of the cells in sphere formation and measuring the expression of stem cell markers. We found that downregulation of Nanog inhibited renal CSC properties. DATS suppressed renal CSC activities by reducing tumorsphere formation, decreasing stem cell markers including Nanog, CD44, ALDH1A1, and Oct4, inhibiting cell proliferation and promoting apoptosis. We further revealed that overexpression of Nanog reversed the suppressive effects of DATS on renal CSCs. Taken together, our results demonstrated that DATS inhibited renal CSCs by suppressing Nanog. These novel findings suggested that, through Nanog targeting, DATS can potentially be used as an anti-tumor agent for renal cancer.

ING4 Promotes Stemness Enrichment of Human Renal Cell Carcinoma Cells Through Inhibiting DUSP4 Expression to Activate the p38 MAPK/type I IFN-Stimulated Gene Signaling Pathway

Renal cell carcinoma (RCC) recurs frequently due to high metastatic spread, resulting in a high mortality. Cancer stem cells play a critical role in initiating the tumor metastasis. Inhibitor of growth 4 (ING4) is a member of the ING family, but its impact on cancer stem cells in RCC is still unknown. In this study, we found that ING4 significantly promoted the sphere-forming size and number of RCC cells under an ultralow-attachment culture condition in vitro, tumor growth and metastasis in vivo, and the expression of some stem-like or pluripotent biomarkers CD44, MYC, OCT4, and NANOG, indicating that ING4 increased the stemness enrichment of RCC cells. Mechanistically, the ING4-activated p38 MAPK pathway possibly upregulated the expression of type I IFN-stimulated genes to promote the formation of RCC stem cells. ING4 could inhibit the expression of DUSP4 to activate p38 MAPK. In addition, selective pharmacological p38 MAPK inhibitors could significantly inhibit stemness enrichment only in ING4-overexpressed RCC cells, suggesting that the p38 MAPK inhibitors might be effective in patients with high ING4 expression in RCC tissue. Taken together, our findings proposed that ING4 might serve as a potential therapeutic target for metastatic RCC, particularly RCC stem cells.

Multi-Omics Analysis of the Effects of Smoking on Human Tumors

Comprehensive studies on cancer patients with different smoking histories, including non-smokers, former smokers, and current smokers, remain elusive. Therefore, we conducted a multi-omics analysis to explore the effect of smoking history on cancer patients. Patients with smoking history were screened from The Cancer Genome Atlas database, and their multi-omics data and clinical information were downloaded. A total of 2,317 patients were included in this study, whereby current smokers presented the worst prognosis, followed by former smokers, while non-smokers showed the best prognosis. More importantly, smoking history was an independent prognosis factor. Patients with different smoking histories exhibited different immune content, and former smokers had the highest immune cells and tumor immune microenvironment. Smokers are under a higher incidence of genomic instability that can be reversed following smoking cessation in some changes. We also noted that smoking reduced the sensitivity of patients to chemotherapeutic drugs, whereas smoking cessation can reverse the situation. Competing endogenous RNA network revealed that mir-193b-3p, mir-301b, mir-205-5p, mir-132-3p, mir-212-3p, mir-1271-5p, and mir-137 may contribute significantly in tobacco-mediated tumor formation. We identified 11 methylation driver genes (including EIF5A2, GBP6, HGD, HS6ST1, ITGA5, NR2F2, PLS1, PPP1R18, PTHLH, SLC6A15, and YEATS2), and methylation modifications of some of these genes have not been reported to be associated with tumors. We constructed a 46-gene model that predicted overall survival with good predictive power. We next drew nomograms of each cancer type. Interestingly, calibration diagrams and concordance indexes are verified that the nomograms were highly accurate for the prognosis of patients. Meanwhile, we found that the 46-gene model has good applicability to the overall survival as well as to disease-specific survival and progression-free intervals. The results of this research provide new and valuable insights for the diagnosis, treatment, and follow-up of cancer patients with different smoking histories.

Targeting Strategies for Renal Cancer Stem Cell Therapy

Renal cell carcinoma (RCC) is an intractable genitourinary malignancy that accounts for approximately 4% of adult malignancies. Currently, there is no approved targeted therapy for RCC that has yielded durable remissions, and they remain palliative in intent. Emerging evidence has indicated that renal tumorigenesis and RCC treatment-resistance may originate from renal cancer stem cells (CSCs) with tumor-initiating capacity (CSC hypothesis). A better understanding of the mechanism underlying renal CSCs will help to dissect RCC heterogeneity and drug treatment efficiency, to promote more personalized and targeted therapies. In this review, we summarized the stem cell characteristics of renal CSCs. We outlined the targeting strategies and challenges associated with developing therapies that target renal CSCs angiogenesis, immunosuppression, signaling pathways, surface biomarkers, microRNAs and nanomedicine. In conclusion, CSCs are an important role in renal carcinogenesis and represent a valid target for treatment of RCC patients.

Novel MicroRNA Binding Site SNPs and the Risk of Clear Cell Renal Cell Carcinoma (ccRCC): A Case-Control Study

BACKGROUND

Renal cell carcinoma represents 3% of all adult malignancies. MicroRNAs exhibit specific functions in various biological processes through their interaction with cellular mRNA involved in apoptosis and cell cycle control. Recent studies have reported the potential association of single-nucleotide polymorphisms (SNPs) in miRNA-binding sites of VHL-HIF1α pathway genes with renal cancer development and progression.

OBJECTIVE

The objective of this study is to investigate SNPs invoking an alteration in the nature of interaction with miRNA binding sites of VHL-HIF1α pathway genes.

PATIENTS & METHODS

Total 450 cases of histologically and clinically verified ccRCC and 490 controls were included in our study. Genotyping was performed using a TaqMan PCR allelic discrimination method. Kaplan-Meier method of statistical analysis was implemented to analyze the overall patient survival rate.

RESULTS

Polymorphism rs10491534 in TSC1 gene was significantly associated with risk of developing advanced ccRCC. Allele G of rs1642742 in VHL gene was significantly prevalent in ccRCC compared with control group aged 55 and older (OR = 1.5566; CI [1.1532-2.1019]). Results from the dominant model combining individuals with AG or AA genotype showed that the A allele bearers of CDCP1 rs6773576 exhibited higher risk of death compared to GG carriers (HR 3.93, 95% CI 1.76-17.21, log-rank P = 0.0033).

CONCLUSION

The present study delineated the association of miRNA binding site variants in VHL-HIF1α pathway genes with the ccRCC risk, which may affect clinical outcome.

Nanog mediates tobacco smoke-induced enhancement of renal cancer stem cell properties

Nanog plays an important role in the regulation of cancer stem cells (CSCs) which participate in tumorgenesis and progression. In renal cancer, tobacco smoke (TS) is considered a major risk factor. However, the molecular mechanism by which TS induces the development of renal CSC properties remains largely unknown. In this study, we showed that the level of Nanog was elevated in renal cell carcinoma (RCC) patients with a smoking history, and that Nanog overexpression promoted the traits of CSCs in renal cancer. We further demonstrated that a 8-week exposure of TS enhanced the formation of renal tumorspheres, increased the population of CD133-positive cells, and stimulated the expression of Nanog and CSC markers. In addition, TS was found to play a role in accelerating the cell growth transition from G1 to S phase in renal CSCs. Finally, we demonstrated that the TS-induced effects in renal CSCs could be reversed through the downregulation of Nanog. Our results suggested that Nanog plays a role in mediating TS-induced renal CSC properties. This study may provide new insights into the molecular mechanism of TS-related renal tumorigenesis, which can contribute to the future development of therapeutics for renal cancer.

Tobacco Smoke Plays an Important Role in Initiation and Development of Lung Cancer by Promoting the Characteristics of Cancer Stem Cells

Lung cancer is one of the most common causes of cancer-related deaths worldwide. Tobacco smoke is the single greatest risk factor of lung cancer. Although enormous progress in understanding the molecular mechanisms by which tobacco smoke leading to lung cancer has been made, the molecular pathogenesis remains largely unclear. Cancer stem cells have been implicated in cancer initiation, development, and drug resistance. In this review, we reviewed the relationship between tobacco smoke and lung cancer, the key role of cancer stem cells in lung cancer and other tumors. More importantly, we elucidate the mechanism of tobacco smoke promoting lung cancer from the perspective of the characteristics of cancer stem cells induced by tobacco smoke.

Emerging role of tumor cell plasticity in modifying therapeutic response

Resistance to cancer therapy is a major barrier to cancer management. Conventional views have proposed that acquisition of resistance may result from genetic mutations. However, accumulating evidence implicates a key role of non-mutational resistance mechanisms underlying drug tolerance, the latter of which is the focus that will be discussed here. Such non-mutational processes are largely driven by tumor cell plasticity, which renders tumor cells insusceptible to the drug-targeted pathway, thereby facilitating the tumor cell survival and growth. The concept of tumor cell plasticity highlights the significance of re-activation of developmental programs that are closely correlated with epithelial-mesenchymal transition, acquisition properties of cancer stem cells, and trans-differentiation potential during drug exposure. From observations in various cancers, this concept provides an opportunity for investigating the nature of anticancer drug resistance. Over the years, our understanding of the emerging role of phenotype switching in modifying therapeutic response has considerably increased. This expanded knowledge of tumor cell plasticity contributes to developing novel therapeutic strategies or combination therapy regimens using available anticancer drugs, which are likely to improve patient outcomes in clinical practice.

Resveratrol Inhibition of Renal Cancer Stem Cell Characteristics and Modulation of the Sonic Hedgehog Pathway

AIMS

Renal cell cancers typically exhibit high metastasis and recurrence, and this is thought to be due to renal cancer stem cells (CSCs). Meanwhile, aberrant activation of Sonic hedgehog (Shh) signaling is linked with CSCs. Resveratrol has direct or indirect impacts on the pathological activities of CSCs. However, the effects of resveratrol on renal CSCs remain to be elucidated.

METHODS

We cultured renal CSCs in serum-free medium. Western blotting was used to analyze the expression levels of related proteins. The mRNA changes were detected by qRT-PCR after resveratrol treatment. The CD133⁺ cells were quantified by flow cytometry analysis. Immunofluorescence staining images showed the changes in CD44 and Smoothened expression in the cell spheres.

RESULTS

Renal CSCs were enriched by tumorsphere formation assays of ACHN and 786-O cells. Resveratrol treatments markedly decreased the size and number of cell spheres and downregulated the expression of the Shh pathway-related proteins and CSCs markers. Moreover, we observed that resveratrol inhibited cell proliferation and induced cell apoptosis, while purmorphamine upregulated the Shh pathway and weakened the effects of resveratrol on renal CSCs.

CONCLUSIONS

These results suggested that resveratrol is a potential novel therapeutic agent that targets inactivation of renal CSCs by affecting the function of the Shh pathway.

Cigarette smoke supports stemness and epithelial-mesenchymal transition in bladder cancer stem cells through SHH signaling

Cancer stem cells (CSCs) are essential in every step of tumorigenesis and progression. As an important process in cancer development, epithelial-mesenchymal transition (EMT) has been reported to promote stem-like cells. Bladder cancer is one of the most common cancers in the urinary tract, and cigarette smoke (CS) is a preventable risk factor. In the present study, we tested the hypothesis that CS could promote stemness and EMT in bladder cancer. Bladder cancer UM-UC-3 and EJ cell lines were maintained in serum-free medium to grow as tumor spheres, characteristic of CSCs. Results demonstrated that CS enhanced tumor sphere formation capacity, upregulated expression of CSC markers, increased the proportion of the CD44⁺ cell population, and promoted EMT. Mechanistically, the Sonic Hedgehog (SHH) pathway regulated CS-triggered EMT and stemness. More importantly, among bladder cancer patients, smokers harbored higher levels of CSC markers and proteins for SHH signaling than non-smokers. Collectively, findings in this study highlight the critical role of CS in the stemness and EMT of bladder cancer. Smoking cessation and intervening in the SHH pathway may both be strategies to prevent bladder cancer.

Life style factors, tumor cell plasticity and cancer stem cells

Cancers are heterogeneous tissues and a layer of heterogeneity is determined by the presence of cells showing stemness traits, known as cancer stem cells (CSCs). Evidence indicates that CSCs are important players in tumor development, progression and relapse. Oncogenic transformation of normal stem cells can give rise to CSCs, but CSCs can also originate from de-differentiation of bulk tumor cells. Thus, factors promoting the increase of normal stem cell pools or stimulating the acquisition of stemness features by tumor cells can have serious consequences on cancer origin and progression. In this review, we will first give an overview of the CSC model of cancer development and we will then discuss the role of life style factors, such as high caloric diet, alcohol drinking and smoking, on the widening of stem cell pools and the induction of CSC features in tumors. Finally, we will discuss some healthy life style factors that can help to prevent cancer.

Potential ameliorative effects of epigallocatechin-3-gallate against cigarette smoke exposure induced renal and hepatic deficits

The environmental pollution caused by cigarette smoke (CS) seriously endangers people's health. Epigallocatechin-3-gallate (EGCG) is the most abundant catechin in green tea. In this study, rats were exposed to CS for 90 days. Kidney function was evaluated by detecting the levels of serum creatinine and blood urea nitrogen. Liver function was evaluated by detecting the activities of alanine aminotransferase and aspartate transaminase. The renal and hepatic oxidative stress and inflammation were assessed by detecting the levels of malondialdehyde, reduced glutathione, antioxidant enzymes (superoxide dismutase and glutathione peroxidase) and proinflammatory cytokines. Organ fibrosis was evaluated by observing collagen deposition via masson staining, by examining the hydroxyproline level, by measuring the mRNA levels of fibrosis-associated genes collagen (Col)-1A1 and Col-3A1, as well as by assessing the activity of profibrotic TGF-β1 pathway. Additionally, renal and hepatic epithelial-mesenchymal transition (EMT) were evaluated. It was observed that EGCG ameliorated the renal and hepatic oxidative stress, inflammation, EMT, as well as inhibited the activation of TGF-β1 signaling pathway induced by CS. These results showed that EGCG could attenuate CS-induced renal and hepatic fibrosis.

Sonic hedgehog pathway mediates genistein inhibition of renal cancer stem cells

Cancer stem cells (CSCs) have been implicated in the genesis, progression and recurrence of renal cancer. The sonic hedgehog (Shh) pathway serves a critical role in maintaining the stemness of CSCs. Genistein, a major isoflavone component extracted from soybeans and soy products, has been demonstrated to possess anticancer activity. However, the effects of genistein on renal CSCs and its underlying mechanisms remain to be fully elucidated. The aim of the present study was to investigate the role of the Shh pathway in genistein inhibition of renal CSCs. The results of the present study demonstrated that expression levels of renal CSC markers were markedly upregulated in the sphere-forming cells, which were isolated and enriched from 786-O and ACHN cells in a tumor sphere formation assay, and more cells were arrested at the G₀/G₁ phase instead of the S₁ phase compared with the adherent cells. Furthermore, the present study demonstrated that genistein could effectively diminish the activity of renal CSCs by suppressing tumor sphere formation, decreasing renal CSCs markers, inhibiting proliferation and inducing apoptosis. Additionally, the downregulation of Shh pathway activity could inhibit renal CSCs. Genistein exhibited an inhibitory effect on renal CSCs by attenuating the activation of the Shh pathway. In conclusion, the results illustrated the role of the Shh pathway in regulating renal CSC traits and the intervention of renal CSCs by genistein, which could provide novel insights into the molecular mechanisms of renal CSC intervention.

Cancer stem cells in breast and prostate: Fact or fiction?

Since the introduction of the cancer stem cell (CSC) hypothesis, accumulating evidence shows that most cancers present stem-like niches. However, therapies aimed at targeting this niche have not been as successful as expected. New evidence regarding CSCs hierarchy, similarities with normal tissue stem cells and cell plasticity might be key in understanding their role in cancer biology and how to efficiently eliminate them. In this Chapter, we discuss what is known in breast and prostate CSCs from their initial discoveries to the current therapeutic efforts in the field. Future challenges towards better CSC identification and isolation strategies will be key to shed light into how CSCs could accurately be targeted in combination to traditional therapies to ultimately prolong patient survival.