Prostate tumour overexpressed-1 promotes tumourigenicity in human breast cancer via activation of Wnt/β-catenin signalling

Post-translational modifications: The potential ways for killing cancer stem cells

While strides in cancer treatment continue to advance, the enduring challenges posed by cancer metastasis and recurrence persist as formidable contributors to the elevated mortality rates observed in cancer patients. Among the multifaceted factors implicated in tumor recurrence and metastasis, cancer stem cells (CSCs) emerge as noteworthy entities due to their inherent resistance to conventional therapies and heightened invasive capacities. Characterized by their notable abilities for self-renewal, differentiation, and initiation of tumorigenesis, the eradication of CSCs emerges as a paramount objective. Recent investigations increasingly emphasize the pivotal role of post-translational protein modifications (PTMs) in governing the self-renewal and replication capabilities of CSCs. This review accentuates the critical significance of several prevalent PTMs and the intricate interplay of PTM crosstalk in regulating CSC behavior. Furthermore, it posits that the manipulation of PTMs may offer a novel avenue for targeting and eliminating CSC populations, presenting a compelling perspective on cancer therapeutics with substantial potential for future applications.

Wnt/β-catenin signaling pathway in carcinogenesis and cancer therapy

The Wnt/β-catenin signaling pathway plays a crucial role in various physiological processes, encompassing development, tissue homeostasis, and cell proliferation. Under normal physiological conditions, the Wnt/β-catenin signaling pathway is meticulously regulated. However, aberrant activation of this pathway and downstream target genes can occur due to mutations in key components of the Wnt/β-catenin pathway, epigenetic modifications, and crosstalk with other signaling pathways. Consequently, these dysregulations contribute significantly to tumor initiation and progression. Therapies targeting the Wnt/β-catenin signaling transduction have exhibited promising prospects and potential for tumor treatment. An increasing number of medications targeting this pathway are continuously being developed and validated. This comprehensive review aims to summarize the latest advances in our understanding of the role played by the Wnt/β-catenin signaling pathway in carcinogenesis and targeted therapy, providing valuable insights into acknowledging current opportunities and challenges associated with targeting this signaling pathway in cancer research and treatment.

Regulation of SUMOylation Targets Associated With Wnt/β-Catenin Pathway

Wnt/β-catenin signaling is a delicate and complex signal transduction pathway mediated by multiple signaling molecules, which plays a significant role in regulating human physiology and pathology. Abnormally activated Wnt/β-catenin signaling pathway plays a crucial role in promoting malignant tumor occurrence, development, recurrence, and metastasis, particularly in cancer stem cells. Studies have shown that the Wnt/β-catenin signaling pathway controls cell fate and function through the transcriptional and post-translational regulation of omics networks. Therefore, precise regulation of Wnt/β-catenin signaling as a cancer-targeting strategy may contribute to the treatment of some malignancies. SUMOylation is a post-translational modification of proteins that has been found to play a major role in the Wnt/β-catenin signaling pathway. Here, we review the complex regulation of Wnt/β-catenin signaling by SUMOylation and discuss the potential targets of SUMOylation therapy.

The interaction of canonical Wnt/β-catenin signaling with protein lysine acetylation

Canonical Wnt/β-catenin signaling is a complex cell-communication mechanism that has a central role in the progression of various cancers. The cellular factors that participate in the regulation of this signaling are still not fully elucidated. Lysine acetylation is a significant protein modification which facilitates reversible regulation of the target protein function dependent on the activity of lysine acetyltransferases (KATs) and the catalytic function of lysine deacetylases (KDACs). Protein lysine acetylation has been classified into histone acetylation and non-histone protein acetylation. Histone acetylation is a kind of epigenetic modification, and it can modulate the transcription of important biological molecules in Wnt/β-catenin signaling. Additionally, as a type of post-translational modification, non-histone acetylation directly alters the function of the core molecules in Wnt/β-catenin signaling. Conversely, this signaling can regulate the expression and function of target molecules based on histone or non-histone protein acetylation. To date, various inhibitors targeting KATs and KDACs have been discovered, and some of these inhibitors exert their anti-tumor activity via blocking Wnt/β-catenin signaling. Here, we discuss the available evidence in understanding the complicated interaction of protein lysine acetylation with Wnt/β-catenin signaling, and lysine acetylation as a new target for cancer therapy via controlling this signaling.

The Cross-Talk between Epigenetic Gene Regulation and Signaling Pathways Regulates Cancer Pathogenesis

Cancer begins due to uncontrolled cell division. Cancer cells are insensitive to the signals that control normal cell proliferation. This uncontrolled cell division is due to the accumulation of abnormalities in different factors associated with the cell division, including different cyclins, cell cycle checkpoint inhibitors, and cellular signaling. Cellular signaling pathways are aberrantly activated in cancer mainly due to epigenetic regulation and post-translational regulation. In this chapter, the role of epigenetic regulation in aberrant activation of PI3K/AKT, Ras, Wnt, Hedgehog, Notch, JAK/STAT, and mTOR signaling pathways in cancer progression is discussed. The role of epigenetic regulators in controlling the upstream regulatory proteins and downstream effector proteins responsible for abnormal cellular signaling-mediated cancer progression is covered in this chapter. Similarly, the role of signaling pathways in controlling epigenetic gene regulation-mediated cancer progression is also discussed. We have tried to ascertain the current status of potential epigenetic drugs targeting several epigenetic regulators to prevent different cancers.

Epigenetic Regulation of the Wnt/β-Catenin Signaling Pathway in Cancer

Studies over the past four decades have elucidated the role of Wnt/β-catenin mediated regulation in cell proliferation, differentiation and migration. These processes are fundamental to embryonic development, regeneration potential of tissues, as well as cancer initiation and progression. In this review, we focus on the epigenetic players which influence the Wnt/β-catenin pathway via modulation of its components and coordinated regulation of the Wnt target genes. The role played by crosstalk with other signaling pathways mediating tumorigenesis is also elaborated. The Hippo/YAP pathway is particularly emphasized due to its extensive crosstalk via the Wnt destruction complex. Further, we highlight the recent advances in developing potential therapeutic interventions targeting the epigenetic machinery based on the characterization of these regulatory networks for effective treatment of various cancers and also for regenerative therapies.

Amplification of RAD54B promotes progression of hepatocellular carcinoma via activating the Wnt/β-catenin signaling

Liver cancer was reported to be the sixth most frequently diagnosed cancer, and hepatocellular carcinoma (HCC) accounts for 75%-85% of primary liver cancer. Nevertheless, the concrete molecular mechanisms of HCC progression remain obscure, which is essential to elucidate. The expression profile of RAD54B in HCC was measured using qPCR and western blotting. Moreover, the levels of RAD54B in paraffin-embedded samples were evaluated using immunohistochemistry (IHC). The effect of RAD54B on HCC progression was testified by in vitro experiments, and in vivo orthotopic xenograft tumor experiments. The mechanisms of RAD54B promoting HCC progression were investigated through molecular and function experiments. Herein, RAD54B are dramatically upregulated in HCC tissues and cell lines both on mRNA and protein levels, and RAD54B can servers as an independent prognostic parameter of 5-year overall survival and 5-year disease-free survival for patients with HCC. Moreover, up-regulation of RAD54B dramatically increases the capacity for in vitro cell viability and motility, and in vivo intrahepatic metastasis of HCC cells. Mechanistically, RAD54B promotes the HCC progression through modulating the wnt/β-catenin signaling. Notably, blocking the wnt/β-catenin signaling axis can counteract the activating effects of RAD54B on motility of HCC cells. Besides, further analysis illustrates that DNA amplification is one of the mechanisms leading to mRNA overexpression of RAD54B in HCC. Our findings indicate that RAD54B might be a promising potential prognostic marker and a candidate therapeutic target to therapy HCC.

miR-140-3p enhances cisplatin sensitivity and attenuates stem cell-like properties through repressing Wnt/β-catenin signaling in lung adenocarcinoma cells

Lung adenocarcinoma (LUAD) is the most predominant subtype of non-small cell lung cancer (NSCLC) that is experiencing the fastest growth rate in incidence. Chemoresistance and the presence of cancer stem cells are considered to be the main obstacles preventing the successful treatment of patients with NSCLC, the molecular mechanism of which remains poorly understood. The present study aimed to investigate the effects of microRNA (miR)-140-3p on cisplatin sensitivity and stem cell-like properties of LUAD cells. Analysis of publicly available data demonstrated that miR-140-3p expression was downregulated in LUAD, and positively associated with the overall survival rate of patients. In addition, transfection with the miR-140-3p mimic reduced LUAD cell viability and induced apoptosis following treatment with cisplatin whilst decreasing stem cell-like properties. miR-140-3p overexpression was also found to attenuate cisplatin resistance and reduce stem cell-like properties in LUAD cells by suppressing Wnt/β-catenin signaling, all of which were reversed by the overexpression of β-catenin. Taken together, results of the present study suggest miR-140-3p to be an effective therapeutic strategy for patients with LUAD.

Depleting PTOV1 sensitizes non-small cell lung cancer cells to chemotherapy through attenuating cancer stem cell traits

Background

Prostate tumor over expressed gene 1 (PTOV1) has been reported as an oncogene in several human cancers. However, the clinical significance and biological role of PTOV1 remain elusive in non-small cell lung cancer (NSCLC).

Methods

The Cancer Genome Atlas (TCGA) data and NCBI/GEO data mining, western blotting analysis and immunohistochemistry were employed to characterize the expression of PTOV1 in NSCLC cell lines and tissues. The clinical significance of PTOV1 in NSCLC was studied by immunohistochemistry statistical analysis and Kaplan–Meier Plotter database mining. A series of in-vivo and in-vitro assays, including colony formation, CCK-8 assays, flow cytometry, wound healing, trans-well assay, tumor sphere formation, quantitative PCR, gene set enrichment analysis (GSEA), immunostaining and xenografts tumor model, were performed to demonstrate the effects of PTOV1 on chemosensitivity of NSCLC cells and the underlying mechanisms.

Results

PTOV1 is overexpressed in NSCLC cell lines and tissues. High PTOV1 level indicates a short survival time and poor response to chemotherapy of NSCLC patients. Depleting PTOV1 increased sensitivity to chemotherapy drugs cisplatin and docetaxel by increasing cell apoptosis, inhibiting cell migration and invasion. Our study verified that depleting PTOV1 attenuated cancer stem cell traits through impairing DKK1/β-catenin signaling to enhance chemosensitivity of NSCLC cells.

Conclusion

These results suggest that PTOV1 plays an important role in the development and progression of human NSCLC and PTOV1 may serve as a therapeutic target for NSCLC patients.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1349-y) contains supplementary material, which is available to authorized users.

Mitofusin 2 inhibits bladder cancer cell proliferation and invasion via the Wnt/β-catenin pathway

The present study aimed to investigate the biological role of the mitochondrial GTPase mitofusin-2 (MFN2) in bladder cancer. MFN2 mRNA expression in tumor and paired adjacent non-tumor tissues from 8 patients was investigated using reverse transcription-quantitative polymerase chain reaction analysis. Immunohistochemistry was used to investigate MFN2 expression in 117 bladder cancer specimens. The associations of MFN2 expression with clinicopathological parameters were evaluated statistically. In addition, the biological role of MFN2 in the proliferation, migration and invasion of bladder cancer cells was examined. It was identified that MFN2 expression was significantly downregulated in bladder cancer tissues compared with normal tissues. MFN2 expression was associated with tumor stage, tumor grade and lymph node status. Furthermore, patients with low MFN2 expression demonstrated a shorter overall survival time (P=0.025). MFN2 knockdown by small interfering RNA promoted cancer cell proliferation, migration and invasion in vitro, and enhanced tumor progression in vivo. Mechanistically, MFN2 was revealed to be involved in Wnt/β-catenin signaling. In conclusion, MFN2 may serve as a potential therapeutic target in the treatment of bladder cancer, and the progress of bladder cancer may be delayed by regulating MFN2 expression.

Implication for Cancer Stem Cells in Solid Cancer Chemo-Resistance: Promising Therapeutic Strategies Based on the Use of HDAC Inhibitors

Resistance to therapy in patients with solid cancers represents a daunting challenge that must be addressed. Indeed, current strategies are still not effective in the majority of patients; which has resulted in the need for novel therapeutic approaches. Cancer stem cells (CSCs), a subset of tumor cells that possess self-renewal and multilineage differentiation potential, are known to be intrinsically resistant to anticancer treatments. In this review, we analyzed the implications for CSCs in drug resistance and described that multiple alterations in morphogenetic pathways (i.e., Hippo, Wnt, JAK/STAT, TGF-β, Notch, Hedgehog pathways) were suggested to be critical for CSC plasticity. By interrogating The Cancer Genome Atlas (TCGA) datasets, we first analyzed the prevalence of morphogenetic pathways alterations in solid tumors with associated outcomes. Then, by highlighting epigenetic relevance in CSC development and maintenance, we selected histone deacetylase inhibitors (HDACi) as potential agents of interest to target this subpopulation based on the pleiotropic effects exerted specifically on altered morphogenetic pathways. In detail, we highlighted the role of HDACi in solid cancers and, specifically, in the CSC subpopulation and we pointed out some mechanisms by which HDACi are able to overcome drug resistance and to modulate stemness. Although, further clinical and preclinical investigations should be conducted to disclose the unclear mechanisms by which HDACi modulate several signaling pathways in different tumors. To date, several lines of evidence support the testing of novel combinatorial therapeutic strategies based on the combination of drugs commonly used in clinical practice and HDACi to improve therapeutic efficacy in solid cancer patients.

β-catenin regulates effects of miR-24 on the viability and autophagy of glioma cells

Mutations of the β-catenin gene are common in various cancer types. MicroRNA (miR)-24 suppresses gene expression during the cell cycle. However, the effects of miR-24 on the cell viability and autophagy of glioma cells, and how these biological processes are regulated by β-catenin are largely unclear. The current study aimed to investigate the role of β-catenin in regulating the effects of miR-24 on the cell viability and autophagy of glioma cells. The expression levels of microtubule-associated proteins 1A/1B light chain 3B (LC3B) and Beclin1 were detected by immunohistochemistry and western blotting. Glioma C6 cells were transfected with miR-24 mimics, miR-24 inhibitors and negative control miRNAs. C6 cells transfected with miR-24 mimics or negative control miRNAs were treated with the β-catenin inhibitor, XAV-939. An MTT assay was utilized to evaluate the viability of C6 cells. The expression of miR-24 and mRNA expression of autophagy related 4a cysteine peptidase (ATG4A) were detected by quantitative polymerase chain reaction analysis. The protein expression of LC3B and Beclin1 decreased significantly in glioma tissue and glioma C6 cells compared with normal brain tissue. Compared with the negative control group, C6 cells transfected with miR-24 mimics exhibited significantly higher cell viability at 24 and 48 h, and those transfected with miR-24 inhibitors exhibited significantly lower cell viability at 48 h. XAV-939 decreased the stimulatory effects of miR-24 mimics on the viability of C6 cells. The expression of miR-24 significantly decreased and ATG4A mRNA significantly increased in C6 cells transfected with XAV-939 compared with those transfected with the negative control miRNA. XAV-939 attenuated the miR-24-induced decrease of the protein expression of LC3B and Beclin1, and decreased the stimulatory effects of miR-24 mimics on cell viability. In addition, XAV-939 attenuated the miR-24-induced decrease of autophagy marker expression by attenuating miR-24 expression and increasing ATG4A mRNA expression in glioma C6 cells. To the best of our knowledge, the present study is the first to demonstrate whether β-catenin regulates the intracellular effects of miR-24 on the viability and autophagy of glioma cells. The results also provide some mechanistic basis to the pharmaceutical targeting of WNT signaling in high grade glial tumors.

A novel DNA-binding motif in prostate tumor overexpressed-1 (PTOV1) required for the expression of ALDH1A1 and CCNG2 in cancer cells

PTOV1 is a transcription and translation regulator and a promoter of cancer progression. Its overexpression in prostate cancer induces transcription of drug resistance and self-renewal genes, and docetaxel resistance. Here we studied PTOV1 ability to directly activate the transcription of ALDH1A1 and CCNG2 by binding to specific promoter sequences. Chromatin immunoprecipitation and electrophoretic mobility shift assays identified a DNA-binding motif inside the PTOV-A domain with similarities to known AT-hooks that specifically interacts with ALDH1A1 and CCNG2 promoters. Mutation of this AT-hook-like sequence significantly decreased the expression of ALDH1A1 and CCNG2 promoted by PTOV1. Immunohistochemistry revealed the association of PTOV1 with mitotic chromosomes in high grade prostate, colon, bladder, and breast carcinomas. Overexpression of PTOV1, ALDH1A1, and CCNG2 significantly correlated with poor prognosis in prostate carcinomas and with shorter relapse-free survival in colon carcinoma. The previously described interaction with translation complexes and its direct binding to ALDH1A1 and CCNG2 promoters found here reveal the PTOV1 capacity to modulate the expression of critical genes at multiple levels in aggressive cancers. Remarkably, the AT-hook motifs in PTOV1 open possibilities for selective targeting its nuclear and/or cytoplasmic activities.

hnRNPK-regulated PTOV1-AS1 modulates heme oxygenase-1 expression via miR-1207-5p

Antisense transcripts were initially identified as transcriptional noise, but have since been reported to play an important role in the quality control of miRNA functions. In this report, we tested the hypothesis that heterogeneous nuclear ribonucleoprotein K (hnRNPK) regulates miRNA function via competitive endogenous RNAs, such as pseudogenes, long non-coding RNAs, and antisense transcripts. Based on analyses of RNA sequencing data, the knockdown of hnRNPK decreased the antisense PTOV1-AS1 transcript which harbors five binding sites for miR-1207-5p. We identified heme oxygenase-1 (HO-1) mRNA as a novel target of miR-1207-5p by western blotting and Ago2 immunoprecipitation. The knockdown of hnRNPK or PTOV1-AS1 suppressed HO-1 expression by increasing the enrichment of HO-1 mRNA in miR-1207-5p-mediated miRISC. Downregulation of HO-1 by a miR-1207-5p mimic or knockdown of hnRNPK and PTOV1-AS1 inhibited the proliferation and clonogenic ability of HeLa cells. Taken together, our results demonstrate that hnRNPKregulated PTOV1-AS1 modulates HO-1 expression via miR- 1207-5p. [BMB Reports 2017; 50(4): 220-225].

Prostate Tumor Overexpressed-1 (PTOV1) promotes docetaxel-resistance and survival of castration resistant prostate cancer cells

Metastatic prostate cancer is presently incurable. The oncogenic protein PTOV1, first described in prostate cancer, was reported as overexpressed and significantly correlated with poor survival in numerous tumors. Here, we investigated the role of PTOV1 in prostate cancer survival to docetaxel and self-renewal ability. Transduction of PTOV1 in docetaxel-sensitive Du145 and PC3 cells significantly increased cell survival after docetaxel exposure and induced docetaxel-resistance genes expression (ABCB1, CCNG2 and TUBB2B). In addition, PTOV1 induced prostatospheres formation and self-renewal genes expression (ALDH1A1, LIN28A, MYC and NANOG). In contrast, Du145 and PC3 cells knockdown for PTOV1 significantly accumulated in the G2/M phase, presented a concomitant increased subG1 peak, and cell death by apoptosis. These effects were enhanced in docetaxel-resistant cells. Analyses of tumor datasets show that PTOV1 expression significantly correlated with prostate tumor grade, drug resistance (CCNG2) and self-renewal (ALDH1A1, MYC) markers. These genes are concurrently overexpressed in most metastatic lesions. Metastases also show PTOV1 genomic amplification in significant co-occurrence with docetaxel-resistance and self-renewal genes. Our findings identify PTOV1 as a promoter of docetaxel-resistance and self-renewal characteristics for castration resistant prostate cancer. The concomitant increased expression of PTOV1, ALDH1A1 and CCNG2 in primary tumors, may predict metastasis and bad prognosis.

Overexpressed PTOV1 associates with tumorigenesis and progression of esophageal squamous cell carcinoma

PTOV1 has been demonstrated to play an extensive role in many types of cancers. This study takes the first step to clarify the potential relationship between esophageal squamous cell carcinoma and PTOV1 expression and highlight the link between PTOV1 and the tumorigenesis, progression, and prognosis of esophageal squamous cell carcinoma. PTOV1 expression was detected by quantitative reverse transcription polymerase chain reaction and western blotting or immunohistochemical staining in esophageal squamous cell carcinoma cell lines, esophageal squamous cell carcinoma tissues, and its paired adjacent non-cancerous tissues. Moreover, we have analyzed the relationship between PTOV1 expression and clinicopathological features of esophageal squamous cell carcinoma. Survival analysis and Cox regression analysis were used to assess its prognostic significance. We found that PTOV1 expression was significantly higher in the esophageal squamous cell carcinoma cell lines and tissues at messenger RNA level (p < 0.001) and protein level (p < 0.001). Gender, tumor size, or differentiation was tightly associated with the PTOV1 expression. Lymph node involvement (p < 0.001) and TNM stage (p < 0.001) promoted a high PTOV1 expression. A prognostic significance of PTOV1 was also found by Log-rank method, and the overexpression of PTOV1 was related to a shorter OS and DFS. Multiple Cox regression analysis indicated overexpressed PTOV1 as an independent indicator for adverse prognosis. In conclusion, this study takes the lead to demonstrate that the overexpressed PTOV1 plays a vital role in the tumorigenesis and progression of esophageal squamous cell carcinoma, and it is potentially a valuable prognostic predicator and new chemotherapeutic target for esophageal squamous cell carcinoma.

miR‑150 inhibits proliferation and tumorigenicity via retarding G1/S phase transition in nasopharyngeal carcinoma

Cancer cells are characterized by a pathological manifestation of uncontrolled proliferation, which results in tumor formation. Therefore, it is necessary to improve understanding of the underlying mechanism of cell cycle control. Here, we report that miR-150 is downregulated in nasopharyngeal carcinoma tissues and cells. Upregulation of miR-150 suppresses nasopharyngeal carcinoma (NPC) cell proliferation and induces G₁/S arrest in vitro, and inhibits tumorigenesis in vivo. Conversely, silencing miR-150 yields the opposite effect. Our results further demonstrate that miR-150 retards nasopharyngeal carcinoma cell proliferation and G₁/S transition via targeting multiple cell cycle-related genes, including CCND1, CCND2, CDK2 and CCNE2. Therefore, our results uncover a novel mechanistic understanding of miR-150-mediated tumor suppression in NPC, which will facilitate the development of effective cancer therapies against nasopharyngeal carcinoma.