Urothelial Carcinoma Stem Cells: Current Concepts, Controversies, and Methods

Overexpression of MicroRNA-138 Affects the Proliferation and Invasion of Urothelial Carcinoma Cells by Suppressing SOX9 Expression

SRY-box transcription factor 9 (SOX9) is important for sexual differentiation, chondrogenic differentiation, and cell proliferation in cancer. It acts as a target molecule of microRNA (miR)-138 in various tumors and is associated with tumor development and growth. In this study, we analyzed the functions of miR-138 and SOX9 in urothelial carcinoma. SOX9 was highly expressed in invasive urothelial carcinoma tissues. miR-138 precursor transfection of T24 and UMUC2 cells significantly decreased SOX9 expression, indicating that SOX9 is a miR-138 target in urothelial carcinoma. Moreover, miR-138 precursor or SOX9 small interfering RNA (siRNA) transfection decreased the proliferation of urothelial carcinoma cell lines. To further confirm that miR-138-SOX9 signaling is involved in cell proliferation and invasion, urothelial carcinoma cells were transfected with the miR-138 precursor or SOX9 siRNA. This transfection reduced the proliferation and invasion of cells via the promotion of autophagy and apoptosis and G0/G1 cell cycle arrest. These results suggest that miR-138-SOX9 signaling modulates the growth and invasive potential of urothelial carcinoma cells.

The G protein-coupled receptor-related gene signatures for predicting prognosis and immunotherapy response in bladder urothelial carcinoma

Bladder urothelial carcinoma (BLCA) is the most common malignant tumor of the urinary tract with a high lethality rate, and its immunotherapy resistance and tumor recurrence have become a major challenge in its clinical treatment. G Protein-Coupled Receptors (GPRs) are the largest family of receptors on the cell membrane surface, involved in multiple signaling pathways, and are excellent targets for oncology drug action. The transcriptome profile, single cell transcriptome profile, and clinical data of BLCA were extracted and integrated from TCGA and GEO databases, respectively. The GPR-related genes were obtained from GSEA-MSigDB database. The GPR-related gene signatures of 15 genes were constructed by using the methods of least absolute shrinkage and selection operator regression, multifactor Cox model. At the same time, tumor microenvironment (TME)-score signatures were constructed based on the immune microenvironment of BLCA, and GPR-TME-score signature was further constructed. The stability of this model was verified by using the external dataset GSE160693. We constructed risk groups by combining BLCA patient prognostic information, and with the help of BLCA scRNA transcriptome profiling, we explored differences in prognosis, immune scores, cell-cell interactions, tumor mutational burden, immune checkpoints, and response to immunotherapy in each risk group. We found that the GPR-TME-score signature was an independent prognostic factor for BLCA patients. the TME-score was a protective factor for the prognosis of BLCA patients. Among BLCA patients, GPR-high + TME-low risk group had the worst prognosis, while GPR-high + TME-high risk group had the best prognosis, and the latter had better immune score and immunotherapy response. The above differences in immune response among the subgroups may be related to the higher immune cell infiltration in the GPR-high + TME-high group. GPR-related gene signatures and TME are closely related to BLCA prognosis and immunotherapy, and GPR-related gene signature can be a useful tool to assess BLCA prognosis and immunotherapy response.

Wnt/β-Catenin Signalling and Its Cofactor BCL9L Have an Oncogenic Effect in Bladder Cancer Cells

Bladder cancer (BC) is characterised by a high recurrence and progression rate. However, the molecular mechanisms of BC progression remain poorly understood. BCL9L, a coactivator of β-catenin was mutated in the 5′ and 3′ untranslated regions (UTRs). We assessed the influence of UTRs mutations on BCL9L, and the role of BCL9L and Wnt/β-catenin signalling in BC cells. UTR mutations were analysed by a luciferase reporter. BCL9L protein was assessed by immunohistochemistry in BC tissues. Cell proliferation was examined by crystal violet staining and by the spheroid model. Moreover, migration and invasion were analysed in real-time using the xCelligence RTCA system. The A > T mutation at 3′ UTR of BCL9L reduces the luciferase reporter mRNA expression and activity. BCL9L is predominantly increased in dysplastic urothelial cells and muscle-invasive BC. Knockdown of BCL9L and inhibition of Wnt/β-catenin signalling significantly repress the proliferation, migration and invasion of Cal29 and T24. In addition, BCL9L knockdown reduces mRNA level of Wnt/β-catenin target genes in Cal29 but not in T24 cells. BCL9L and Wnt/β-catenin signalling play an oncogenic role in bladder cancer cells and seems to be associated with BC progression. Nevertheless, the involvement of BCL9L in Wnt/β-catenin signalling is cell-line specific.

Sox9-expressing cells promote regeneration after radiation-induced lung injury via the PI3K/AKT pathway

Background

Radiation-induced lung injury (RILI) is considered one of the most common complications of thoracic radiation. Recent studies have focused on stem cell properties to obtain ideal therapeutic effects, and Sox9 has been reported to be involved in stem cell induction and differentiation. However, whether Sox9-expressing cells play a role in radiation repair and regeneration remains unknown.

Methods

We successfully obtained Sox9^CreER, Rosa^tdTomato and Rosa^DTA mice and identified Sox9-expressing cells through lineage tracing. Then, we evaluated the effects of the ablation of Sox9-expressing cells in vivo. Furthermore, we investigated the underlying mechanism of Sox9-expressing cells during lung regeneration via an online single-cell RNA-seq dataset.

Results

In our study, we demonstrated that Sox9-expressing cells promote the regeneration of lung tissues and that ablation of Sox9-expressing cells leads to severe phenotypes after radiation damage. In addition, analysis of an online scRNA-Seq dataset revealed that the PI3K/AKT pathway is enriched in Sox9-expressing cells during lung epithelium regeneration. Finally, the AKT inhibitor perifosine suppressed the regenerative effects of Sox9-expressing cells and the AKT pathway agonist promotes proliferation and differentiation.

Conclusions

Taken together, the findings of our study suggest that Sox9-expressing cells may serve as a therapeutic target in lung tissue after RILI.

High-dimensional single-cell proteomics analysis reveals the landscape of immune cells and stem-like cells in renal tumors

Background

Renal tumors are highly heterogeneous, and identification of tumor heterogeneity is an urgent clinical need for effective treatment. Mass cytometry (MC) can be used to perform high‐dimensional single‐cell proteomics analysis of heterogeneous samples via cytometry by time‐of‐flight (CyTOF), in order to achieve more accurate observation and classification of phenotypes within a cell population. This study aimed to develop a high‐dimensional MC method for the detection and analysis of heterogeneity in renal tumors.

Materials and Methods

We collected tissue samples from 8 patients with different types of renal tumors. Single‐cell suspensions were prepared and stained using a panel of 28 immune cell‐centric antibodies and a panel of 21 stem‐like cell‐centric antibodies. The stained cells were detected using CyTOF.

Result

Renal tumors were divided into 25 immune cell subsets (4 CD4+ T cells, 7 CD8+ T cells, 1 B cells, 8 macrophages, 1 dendritic cells, 2 natural killer (NK) cells, 1 granulocyte, and 1 other subset) and 7 stem‐like cells subsets (based on positivity of vimentin, CD326, CD34, CD90, CD13, CD44, and CD47). Different types of renal tumors have different cell subsets with significantly different characteristics.

Conclusion

High‐dimensional single‐cell proteomics analysis using MC aids in the discovery and analysis of renal tumors heterogeneity. Additionally, it can be used to accurately classify the immune cell population and analyze the expression of stem cell‐related markers in renal tumors. Our findings provide a valuable resource for deciphering tumor heterogeneity and might improve the clinical management of patients with renal tumors.

Therapeutic approaches targeting cancer stem cells

Increasing studies have demonstrated that most tumors consisted a subpopulation of cells with stem cell properties, known as cancer stem cells (CSCs). Accumulating evidence indicated that CSCs may be critical driving force for several types of cancer. Hence, it was necessary to develop therapeutic approaches specifically targeting CSCs. In this review, first, the biological properties of CSCs were introduced, including the self-renewal and differentiation, high tumorigenesis and invasiveness, resistance to chemotherapy and radiotherapy, genetic and epigenetic variations. Meanwhile, CSCs-targeted therapeutic strategies were summarized, including targeting cell surface markers, signaling pathways, CSC niches, differentiation therapy, and drug resistance for CSCs. Furthermore, clinical trials on anti-CSCs therapies supported the efficacy of these therapies, as well as their combination with conventional chemotherapy and radiotherapy. CSCs could be significantly eradicated, eventually resulting in inhibited tumor growth, metastasis, and recurrence. Thus, selectively targeting CSCs with various agents may be a novel and promising therapeutic strategy against cancer.

Urothelial Cancer Stem Cell Heterogeneity

Urothelial carcinoma is a tumor type featuring pronounced intertumoral heterogeneity and a high mutational and epigenetic load. The two major histopathological urothelial carcinoma types - the non-muscle-invasive and muscle-invasive urothelial carcinoma - markedly differ in terms of their respective typical mutational profiles and also by their probable cells of origin, that is, a urothelial basal cell for muscle-invasive carcinomas and a urothelial intermediate cell for at least a large part of non-muscle-invasive carcinomas. Both non-muscle-invasive and muscle-invasive urothelial carcinomas can be further classified into discrete intrinsic subtypes based on their typical transcriptomic profiles. Urothelial carcinogenesis shows a number of parallels to a urothelial regenerative response. Both of these processes seem to be dominated by specific stem cell populations. In the last years, the nature and location of urothelial stem cell(s) have been subject to many controversies, which now seem to be settled down, favoring the existence of a largely single urothelial stem cell type located among basal cells. Basal cell markers have also been amply used to identify urothelial carcinoma stem cells, especially in muscle-invasive disease, but they proved useful even in some non-muscle-invasive tumors. Analyses on molecular nature of urothelial carcinoma stem cells performed till now point to their great heterogeneity, both during the tumor development and upon intertumoral comparison, sexual dimorphism providing a special example of the latter. Moreover, urothelial cancer stem cells are endowed with intrinsic plasticity, whereby they can modulate their stemness in relation to other tumor-related traits, especially motility and invasiveness. Such transitional modulations suggest underlying epigenetic mechanisms and, even within this context, inter- and intratumoral heterogeneity becomes apparent. Multiple molecular aspects of urothelial cancer stem cell biology markedly influence therapeutic response, implying their knowledge as a prerequisite to improved therapies of this disease. At the same time, the notion of urothelial cancer stem cell heterogeneity implies that this therapeutic benefit would be most probably and most efficiently achieved within the context of individualized antitumor therapy.

YAP regulates ALDH1A1 expression and stem cell property of bladder cancer cells

Background

Yes-associated protein (YAP), a key player of the Hippo pathway, has been identified to have more and more important roles in tumorigenesis and may be an important biomarker for cancer therapy. YAP is important for bladder cancer cell migration, metastasis, and drug resistance; however, its function in bladder cancer stem cells remains unknown.

Purpose

The aim of this work was to examine the expression and role of YAP in bladder cancer stem cells.

Materials and methods

We identified that the expression level of YAP was significantly enriched in bladder cancer stem cells compared to noncancer stem cell population. Moreover, the effect of YAP on stem cell self-renewal was examined in bladder cancer cells by siRNA silencing approach. In addition, we showed that YAP is required for aldehyde dehydrogenase activity in bladder cancer cells.

Results

RNAseq analysis and quantitative real-time PCR results showed that silencing of YAP inhibited the expression of ALDH1A1 gene.

Conclusion

Collectively, our findings for the first time elucidated that YAP serves as a cancer stem cell regulator in bladder cancer, which provided a promising therapy strategy for patients with bladder cancer.