The SUMO System and TGFβ Signaling Interplay in Regulation of Epithelial-Mesenchymal Transition: Implications for Cancer Progression

The Role of EMT-Related lncRNAs in Ovarian Cancer

Ovarian cancer (OC) is one of the deadliest cancers worldwide; late diagnosis and drug resistance are two major factors often responsible for high morbidity and treatment failure. Epithelial-to-mesenchymal transition (EMT) is a dynamic process that has been closely linked with cancer. Long non-coding RNAs (lncRNAs) have been also associated with several cancer-related mechanisms, including EMT. We conducted a literature search in the PubMed database in order to sum up and discuss the role of lncRNAs in regulating OC-related EMT and their underlying mechanisms. Seventy (70) original research articles were identified, as of 23 April 2023. Our review concluded that the dysregulation of lncRNAs is highly associated with EMT-mediated OC progression. A comprehensive understanding of lncRNAs' mechanisms in OC will help in identifying novel and sensitive biomarkers and therapeutic targets for this malignancy.

Possible molecular mechanisms underlying the development of atherosclerosis in cancer survivors

Cancer survivors undergone treatment face an increased risk of developing atherosclerotic cardiovascular disease (CVD), yet the underlying mechanisms remain elusive. Recent studies have revealed that chemotherapy can drive senescent cancer cells to acquire a proliferative phenotype known as senescence-associated stemness (SAS). These SAS cells exhibit enhanced growth and resistance to cancer treatment, thereby contributing to disease progression. Endothelial cell (EC) senescence has been implicated in atherosclerosis and cancer, including among cancer survivors. Treatment modalities for cancer can induce EC senescence, leading to the development of SAS phenotype and subsequent atherosclerosis in cancer survivors. Consequently, targeting senescent ECs displaying the SAS phenotype hold promise as a therapeutic approach for managing atherosclerotic CVD in this population. This review aims to provide a mechanistic understanding of SAS induction in ECs and its contribution to atherosclerosis among cancer survivors. We delve into the mechanisms underlying EC senescence in response to disturbed flow and ionizing radiation, which play pivotal role in atherosclerosis and cancer. Key pathways, including p90RSK/TERF2IP, TGFβR1/SMAD, and BH4 signaling are explored as potential targets for cancer treatment. By comprehending the similarities and distinctions between different types of senescence and the associated pathways, we can pave the way for targeted interventions aim at enhancing the cardiovascular health of this vulnerable population. The insights gained from this review may facilitate the development of novel therapeutic strategies for managing atherosclerotic CVD in cancer survivors.

UTP18-mediated p21 mRNA instability drives adenoma-carcinoma progression in colorectal cancer

Colorectal cancer (CRC) often develops slowly from adenoma, but the underlying mechanism remains unclear, hampering the prevention or treatment of colorectal adenoma-carcinoma progression. In this study, we use in-depth quantitative proteomics combined with survival analysis, revealing that the ribosome protein U3 small nucleolar RNA-associated protein 18 homolog (UTP18) is consistently upregulated in the progression of colorectal adenoma to carcinoma and is associated with adenoma recurrence, effective serodiagnosis, and poor prognosis of CRC. Furthermore, deSUMOylation induces the nucleocytoplasmic transport of UTP18, driving cell-cycle progression and tumorigenesis via mediation of the instability of p21 mRNA. In addition, the growth and ribosome biogenesis of adenoma organoids is found to be promoted by overexpression of UTP18. Thus, UTP18 contributes to multiple roles in adenogenesis and malignancy of CRC, suggesting that it could be a potential biomarker and drug target for colorectal adenoma and cancer.

Unraveling the function of epithelial-mesenchymal transition (EMT) in colorectal cancer: Metastasis, therapy response, and revisiting molecular pathways

Colorectal cancer (CRC) is a dangerous form of cancer that affects the gastrointestinal tract. It is a major global health concern, and the aggressive behavior of tumor cells makes it difficult to treat, leading to poor survival rates for patients. One major challenge in treating CRC is the metastasis, or spread, of the cancer, which is a major cause of death. In order to improve the prognosis for patients with CRC, it is necessary to focus on ways to inhibit the cancer's ability to invade and spread. Epithelial-mesenchymal transition (EMT) is a process that is linked to the spread of cancer cells, also known as metastasis. The process transforms epithelial cells into mesenchymal ones, increasing their mobility and ability to invade other tissues. This has been shown to be a key mechanism in the progression of colorectal cancer (CRC), a particularly aggressive form of gastrointestinal cancer. The activation of EMT leads to increases in the spread of CRC cells, and during this process, levels of the protein E-cadherin decrease while levels of N-cadherin and vimentin increase. EMT also contributes to the development of resistance to chemotherapy and radiation therapy in CRC. Non-coding RNAs, such as long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), play a role in regulating EMT in CRC, often through their ability to "sponge" microRNAs. Anti-cancer agents have been shown to suppress EMT and reduce the progression and spread of CRC cells. These findings suggest that targeting EMT or related mechanisms may be a promising approach for treating CRC patients in the clinic.

Hepatitis B virus X protein increases LASP1 SUMOylation to stabilize HER2 and facilitate hepatocarcinogenesis

The hepatitis B virus (HBV) X protein (HBX), a viral macromolecule, plays a vital role in the development of HBV-related hepatocellular carcinoma (HCC). Increased expression of HER2 is linked to HBV infection, and HBX is responsible for HER2 upregulation in HCC. Nevertheless, the underlying molecular mechanisms are not yet fully understood. In the study, we discovered that HBX promoted HER2 expression to facilitate the sensitization of the insulin signaling pathway and enhance the growth and migration of HCC cells. Mechanistically, the viral protein enhanced the stability of HER2 by preventing its ubiquitination-mediated proteasomal degradation through LASP1, which could bind to HER2. Furthermore, increased SUMOylation of LASP1 contributed to the upregulation of HER2 and the interaction of LASP1 with HER2. In addition, RANBP2 and RANGAP1 were found to interact with LASP1 and promote SUMOylation of LASP1 to upregulate HER2 expression in HBX-associated hepatoma cells. In summary, our work provides a novel insight into hepatocarcinogenesis mediated by HBX and estimates the detailed mechanisms related to the increase in HER2 regulated by the viral protein, which might help provide a theoretical basis for identifying novel targets for HBV-positive HCC treatment.

Circulating microRNAs in Early Breast Cancer Patients and Its Association With Lymph Node Metastases

MicroRNAs have emerged as important regulators of the metastatic process. In addition, circulating miRNAs appear to be surprisingly stable in peripheral blood making them ideal noninvasive biomarkers for disease diagnosis. Here, we performed a proof-of-principle study to investigate the expression profile of circulating miRNAs and their association with the metastatic lymph node status in early breast cancer patients. Sentinel lymph node status was detected by one-step nucleic acid (OSNA) analysis. We performed RNA-sequencing in 16 plasma samples and validated the results by qPCR. Gene Ontology term enrichment and KEGG pathway analyses were carried out using DAVID tools. We found16 differentially expressed miRNAs (q < 0.01) in patients with positive SLNs. Fourteen miRNAs were down-regulated (miR-339-5p, miR-133a-3p, miR-326, miR-331-3p, miR-369-3p, miR-328-3p, miR-26a-3p, miR-139-3p, miR-493-3p, miR-664a-5p, miR-146a-5p, miR-323b-3p, miR-1307-3p and miR-423-3p) and 2 were up-regulated (miR-101-3pand miR-144-3p). Hierarchical clustering using differentially expressed miRNAs clearly distinguished patients according to their lymph node status. Gene ontology analysis showed a significant enrichment of biological processes associated with the regulation of the epithelial mesenchymal transition, cell proliferation and transcriptional regulation. Our results suggest the potential role of several circulating miRNAs as surrogate markers of lymph node metastases in early breast cancer patients. Further validation in a larger cohort of patients will be necessary to confirm our results.

Novel insights into the impact of the SUMOylation pathway in hematological malignancies (Review)

The small ubiquitin-like modifier (SUMO) system serves an important role in the regulation of protein stability and function. SUMOylation sustains the homeostatic equilibrium of protein function in normal tissues and numerous types of tumor. Accumulating evidence has revealed that SUMO enzymes participate in carcinogenesis via a series of complex cellular or extracellular processes. The present review outlines the physiological characteristics of the SUMOylation pathway and provides examples of SUMOylation participation in different cancer types, including in hematological malignancies (leukemia, lymphoma and myeloma). It has been indicated that the SUMO pathway may influence chromosomal instability, cell cycle progression, apoptosis and chemical drug resistance. The present review also discussed the possible relationship between SUMOylation and carcinogenic mechanisms, and evaluated their potential as biomarkers and therapeutic targets in the diagnosis and treatment of hematological malignancies. Developing and investigating inhibitors of SUMO conjugation in the future may offer promising potential as novel therapeutic strategies.

Genetic alteration and clinical significance of SUMOylation regulators in multiple cancer types

The purpose of this study was to investigate the genetic variation, gene expression differences, and clinical significance of SUMOylation regulators in pan-cancers. Based on previous studies, we gained a better understanding of the biological process of SUMOylation and the status of current research. In the present study, we employed a wide range of bioinformatics methods. We used genetic variation and mRNA expression data in the Cancer Genome Atlas (TCGA) to construct a panoramic view of the single nucleotide variants, copy number variants, and gene expression changes in SUMOylation regulators in various tumors. Subsequently, we used the String website and the Cytoscape tool to construct the PPI network between these regulators. We used the GSCALite website to determine the relationship between these regulators and cancer pathways and drug sensitivity. We constructed images of co-expression between these regulators using the R programming language. Using clinical data from TCGA, we performed hazard ratio analysis for these regulators in pan-cancer. Most importantly, we used these regulators to successfully establish risk signatures related to patient prognosis in multiple tumors. Finally, in KIRC, we conducted gene-set enrichment analysis (GSEA) of the five molecules in its risk signatures. We found that these five molecules are involved in multiple cancer pathways. In short, we have comprehensively interpreted the detailed biological process of SUMOylation at the genetic level for the first time, successfully constructed multiple risk signatures, and conducted GSEA in KIRC. We believe that these findings provide credible and valuable information that is relevant for future clinical diagnoses and scientific research.

Arecoline induces epithelial mesenchymal transition in HK2 cells by upregulating the ERK-mediated signaling pathway

Arecoline, a component of betel nuts, is a known carcinogen that causes oral cancers among those who chew betel nuts. Betel nut chewing is also associated with an increased risk of chronic kidney disease (CKD), but the role of arecoline in this association is unclear. This in vitro study investigates the effects of arecoline on cultured human kidney (HK2) cells. We observed that arecoline had no effect on cell viability but increased cell migration in a dose-dependent manner. Western blot analysis showed that arecoline treatment caused a dose-dependent decrease in E-cadherin expression and dose-dependent increases in N-cadherin, vimentin, α-SMA, and collagen expression; reverse transcriptase-polymerase chain reaction analysis revealed dose-dependent increases in α-SMA and collagen mRNA. Arecoline treatment upregulated the expression of phosphorylated extracellular signal-regulated kinase through epithelial mesenchymal transition and renal fibrosis in HK2 cells. These findings demonstrate that arecoline plays a role in inducing the epithelial mesenchymal transition and fibrogenesis in renal tubule cells and suggest that arecoline promotes the progression of CKD.

PIAS1 and TIF1γ collaborate to promote SnoN SUMOylation and suppression of epithelial-mesenchymal transition

SUMO E3 ligases specify protein substrates for SUMOylation. The SUMO E3 ligases PIAS1 and TIF1γ target the transcriptional regulator SnoN for SUMOylation leading to suppression of epithelial-mesenchymal transition (EMT). Whether and how TIF1γ and PIAS1 might coordinate SnoN SUMOylation and regulation of EMT remained unknown. Here, we reveal that SnoN associates simultaneously with both TIF1γ and PIAS1, leading to a trimeric protein complex. Hence, PIAS1 and TIF1γ collaborate to promote the SUMOylation of SnoN. Importantly, loss of function studies of PIAS1 and TIF1γ suggest that these E3 ligases act in an interdependent manner to suppress EMT of breast cell-derived tissue organoids. Collectively, our findings unveil a novel mechanism by which SUMO E3 ligases coordinate substrate SUMOylation with biological implications.

The Post-translational Modifications of Smurf2 in TGF-β Signaling

Smad ubiquitin regulatory factor 2 (Smurf2), an essential negative regulator of TGF-β signaling, ubiquitinates TGF-β receptors (TβRs) and Smad proteins, inducing their proteasomal degradation. Smurf2 plays crucial roles in regulating TGF-β signaling and maintaining normal cellular functions and tissue homeostasis; dysfunction of Smurf2 triggers abnormal TGF-β signaling in pathological states. Smurf2 has been reported as a potentially strong candidate for targeting therapies for related diseases. Recent work has begun to focus on the regulation of Smurf2 itself, and emerging evidence indicates that Smurf2 is regulated by post-translational modifications (PTMs) mechanisms. These mechanisms predominantly regulate the expression level and E3 ligase activity of Smurf2, strongly suggesting that this protein contributes to complicated roles under multiple pathophysiological conditions. In this review, we cover some significant and novel mechanisms of the PTMs that potentially control Smurf2 participation in TGF-β signaling, including ubiquitylation, SUMOylation, neddylation, phosphorylation, and methylation in order to provide a broad view of the depth and sophistication of Smurf2 function in TGF-β regulation, as well as perspectives for future therapeutic directions for its associated diseases.

The role of proteases in epithelial-to-mesenchymal cell transitions in cancer

Changing the characteristics of cells from epithelial states to mesenchymal properties is a key process involved in developmental and physiological processes as well as in many diseases with cancer as the most prominent example. Nowadays, a great deal of work and literature concerns the understanding of the process of epithelial-to-mesenchymal transition (EMT) in terms of its molecular regulation and its implications for cancer. Similar statements can certainly be made regarding the investigation of the more than 500 proteases typically encoded by a mammalian genome. Specifically, the impact of proteases on tumor biology has been a long-standing topic of interest. However, although EMT actively regulates expression of many proteases and proteolytic enzymes are clearly involved in survival, division, differentiation, and movements of cells, information on the diverse roles of proteases in EMT has been rarely compiled. Here we aim to conceptually connect the scientific areas of "EMT" and "protease" research by describing how several important classes of proteolytic enzymes are regulated by EMT and how they are involved in initiation and execution of the EMT program. To do so, we briefly introduce the evolving key features of EMT and its regulation followed by discussion of protease involvement in this process.

Effects of Huaier Polysaccharide SP1 on Gastric Cancer Cell Proliferation, Apoptosis, Migration, and Invasion by Regulating TGF-β/SMAD Signaling Pathway

Objective. To study the effects of Huaier polysaccharide SP1 on the proliferation, apoptosis, migration, and invasion of gastric cancer cell line MGC-803 and the underlying mechanism. Methods. MGC-803 cells were cultured in vitro and treated with SP1. The effects of SP1 on the proliferation, apoptosis, migration, and invasion of MGC-803 cells were detected by CCK-8 assay, flow cytometry analysis, and Transwell assay, respectively. Western blot and qRT-PCR were used to detect the expression of related genes. Results. Our study showed that Huaier polysaccharide SP1 could inhibit proliferation, migration, invasion, and promote the apoptosis of MGC-803 cells in vitro in a dose-dependent manner. Huaier polysaccharide SP1 could inhibit the activation of TGF-β/SMAD signal pathway by upregulating SMAD7 expression, thereby downregulating the expression of SOX4, ZEB2, MMP9, Snail, and Slug. Conclusion. Huaier polysaccharide SP1 can regulate the proliferation, apoptosis, migration, and invasion of gastric cancer cells by promoting the expression of SMAD7 and inhibiting the activation of TGF-β/SMAD signal pathway as well as the expression of the downstream oncogenes.

Ubiquitin, SUMO, and Nedd8 as Therapeutic Targets in Cancer

Ubiquitin defines a family of approximately 20 peptidic posttranslational modifiers collectively called the Ubiquitin-like (UbLs). They are conjugated to thousands of proteins, modifying their function and fate in many ways. Dysregulation of these modifications has been implicated in a variety of pathologies, in particular cancer. Ubiquitin, SUMO (-1 to -3), and Nedd8 are the best-characterized UbLs. They have been involved in the regulation of the activity and/or the stability of diverse components of various oncogenic or tumor suppressor pathways. Moreover, the dysregulation of enzymes responsible for their conjugation/deconjugation has also been associated with tumorigenesis and cancer resistance to therapies. The UbL system therefore constitutes an attractive target for developing novel anticancer therapeutic strategies. Here, we review the roles and dysregulations of Ubiquitin, SUMO, and Nedd8 pathways in tumorigenesis, as well as recent advances in the identification of small molecules targeting their conjugating machineries for potential application in the fight against cancer.

PIAS1 is not suitable as a urothelial carcinoma biomarker protein and pharmacological target

Urothelial cancer (UC) is one of the most common cancers in Europe and is also one of the costliest to treat. When first line therapies show initial success, around 50% of cancers relapse and proceed to metastasis. In this study we assessed the Protein inhibitor of activated signal transducers and activators of transcription (PIAS)1 as a potential therapeutic target in urothelial cancer. PIAS1 is a key regulator of STAT1 signalling and may be implicated in carcinogenesis. In contrast to other cancer types PIAS1 protein expression is not significantly different in malignant areas of UC specimens compared to non-malignant tissue. In addition, we found that down-regulation and overexpression of PIAS1 had no effect on the viability or colony forming ability of tested cell lines. Whilst other studies of PIAS1 suggest an important biological role in cancer, this study shows that PIAS1 has no influence on reducing the cytotoxic effects of Cisplatin or cell recovery after DNA damage induced by irradiation. Taken together, these in vitro data demonstrate that PIAS1 is not a promising therapeutic target in UC cancer as previously shown in different entities such as prostate cancer (PCa).

TGF-β induces PML SUMOylation, degradation and PML nuclear body disruption

ProMyelocytic Leukemia (PML) protein is essential for the formation of nuclear matrix-associated organelles named PML nuclear bodies (NBs) that act as a platform for post-translational modifications and protein degradation. PML NBs harbor transiently and permanently localized proteins and are associated with the regulation of several cellular functions including apoptosis. There are seven PML isoforms, six nuclear (PMLI-VI) and one cytoplasmic (PMLVII), which are encoded by a single gene via alternative RNA splicing. It has been reported that murine PML-null primary cells are resistant to TGF-β-induced apoptosis and that cytoplasmic PML is an essential activator of TGF-β signaling. The role and the fate of interferon (IFN)-enhanced PML NBs in response to TGF-β have not been investigated. Here we show that IFNα potentiated TGF-β-mediated apoptosis in human cells. IFNα or ectopic expression of PMLIV, but not of PMLIII, enhanced TGF-β-induced caspase 8 activation. In response to TGF-β, both PMLIII and PMLIV were conjugated to SUMO and shifted from the nucleoplasm to the nuclear matrix, however only PMLIV, via its specific C-terminal region, interacted with caspase 8 and recruited it within PML NBs. This process was followed by a caspase-dependent PML degradation and PML NB disruption. Taken together, these findings highlight the role of PML NBs in the enhancement by IFN of TGF-β-induced apoptosis and caspase 8 activation.

TGF-β Signaling in Cancer: Control by Negative Regulators and Crosstalk with Proinflammatory and Fibrogenic Pathways

The transforming growth factor-β (TGF-β) family of secreted growth factors controls many aspects of cell and tissue physiology in multicellular eukaryotes. Dysregulation of its pathway contributes to a broad variety of pathologies, including fibrosis and cancer. TGF-β acts as a powerful tumor suppressor in epithelial cells but during later stages of tumor development cancer cells eventually respond to this cytokine with epithelial-mesenchymal transition (EMT), invasion, metastasis, and immunosuppression. This collection of articles covers some important aspects of TGF-β signaling in cancer. Two articles focus on the role of TGF-β in tumor immunity and pro- and anti-inflammatory signaling, with one analyzing its impact on T-cell biology and different T-cell subsets, while the other deals with modulation of anti-inflammatory signaling by TGF-β receptors through proinflammatory signaling by immune receptors and the role of mechanotransduction in TGF-β-dependent immunosuppression. Another set of four chapters highlights the fact that context-dependent responsiveness to TGF-β is largely controlled by inputs from negative regulators and cooperation with proinflammatory and proapoptotic pathways. This theme is extended to the regulation of Smad signaling by differential phosphorylation, eventually converting canonical Smad signaling to a mitogenic, fibrogenic and carcinogenic outcome. Last, it is discussed how another posttranslational modification, SUMOylation, can modify protein function and impact TGF-β-induced EMT, invasion and metastasis.

Signaling Pathways Induced by Leptin during Epithelial⁻Mesenchymal Transition in Breast Cancer

Leptin is an adipokine that is overexpressed in obese and overweight people. Interestingly, women with breast cancer present high levels of leptin and of its receptor ObR. Leptin plays an important role in breast cancer progression due to the biological processes it participates in, such as epithelial⁻mesenchymal transition (EMT). EMT consists of a series of orchestrated events in which cell⁻cell and cell⁻extracellular matrix interactions are altered and lead to the release of epithelial cells from the surrounding tissue. The cytoskeleton is also re-arranged, allowing the three-dimensional movement of epithelial cells into the extracellular matrix. This transition provides cells with the ability to migrate and invade adjacent or distal tissues, which is a classic feature of invasive or metastatic carcinoma cells. In recent years, the number of cases of breast cancer has increased, making this disease a public health problem worldwide and the leading cause of death due to cancer in women. In this review, we focus on recent advances that establish: (1) leptin as a risk factor for the development of breast cancer, and (2) leptin as an inducer of EMT, an event that promotes tumor progression.