Inhibition of SMYD2 suppresses tumor progression by down-regulating microRNA-125b and attenuates multi-drug resistance in renal cell carcinoma

The expression of MIR125B transcripts and bone phenotypes in Mir125b2-deficient mice

MIR125B, particularly its 5p strand, is apparently involved in multiple cellular processes, including osteoblastogenesis and osteoclastogenesis. Given that MIR125B is transcribed from the loci Mir125b1 and Mir125b2, three mature transcripts (MIR125B-5p, MIR125B1-3p, and MIR125B2-3p) are generated (MIR125B-5p is common to both); however, their expression profiles and roles in the bones remain poorly understood. Both primary and mature MIR125B transcripts were differentially expressed in various organs, tissues, and cells, and their expression patterns did not necessarily correlate in wild-type (WT) mice. We generated Mir125b2 knockout (KO) mice to examine the contribution of Mir125b2 to MIR125B expression profiles and bone phenotypes. Mir125b2 KO mice were born and grew normally without any changes in bone parameters. Interestingly, in WT and Mir125b2 KO, MIR125B-5p was abundant in the calvaria and bone marrow stromal cells. These results indicate that the genetic ablation of Mir125b2 does not impinge on the bones of mice, attracting greater attention to MIR125B-5p derived from Mir125b1. Future studies should investigate the conditional deletion of Mir125b1 and both Mir125b1 and Mir125b2 in mice.

5-Fluorouracil dose escalation generated desensitized colorectal cancer cells with reduced expression of protein methyltransferases and no epithelial-to-mesenchymal transition potential

Background

Colorectal cancer (CRC) is one of the most frequently diagnosed cancers. In many cases, the poor prognosis of advanced CRC is associated with resistance to treatment with chemotherapeutic drugs such as 5-Fluorouracil (5-FU). The epithelial-to-mesenchymal transition (EMT) and dysregulation in protein methylation are two mechanisms associated with chemoresistance in many cancers. This study looked into the effect of 5-FU dose escalation on EMT and protein methylation in CRC.

Materials and Methods

HCT-116, Caco-2, and DLD-1 CRC cell lines were exposed to dose escalation treatment of 5-FU. The motility and invasive potentials of the cells before and after treatment with 5-FU were investigated through wound healing and invasion assays. This was followed by a Western blot which analyzed the protein expressions of the epithelial marker E-cadherin, mesenchymal marker vimentin, and the EMT transcription factor (EMT-TF), the snail family transcriptional repressor 1 (Snail) in the parental and desensitized cells. Western blotting was also conducted to study the protein expressions of the protein methyltransferases (PMTs), Euchromatic histone lysine methyltransferase 2 (EHMT2/G9A), protein arginine methyltransferase (PRMT5), and SET domain containing 7/9 (SETD7/9) along with the global lysine and arginine methylation profiles.

Results

The dose escalation method generated 5-FU desensitized CRC cells with distinct morphological features and increased tolerance to high doses of 5-FU. The 5-FU desensitized cells experienced a decrease in migration and invasion when compared to the parental cells. This was reflected in the observed reduction in E-cadherin, vimentin, and Snail in the desensitized cell lines. Additionally, the protein expressions of EHMT2/G9A, PRMT5, and SETD7/9 also decreased in the desensitized cells and global protein lysine and arginine methylation became dysregulated with 5-FU treatment.

Conclusion

This study showed that continuous, dose-escalation treatment of 5-FU in CRC cells generated 5-FU desensitized cancer cells that seemed to be less aggressive than parental cells.

Methylation of ESCRT-III components regulates the timing of cytokinetic abscission

Abscission is the final stage of cytokinesis, which cleaves the intercellular bridge (ICB) connecting two daughter cells. Abscission requires tight control of the recruitment and polymerization of the Endosomal Protein Complex Required for Transport-III (ESCRT-III) components. We explore the role of post-translational modifications in regulating ESCRT dynamics. We discover that SMYD2 methylates the lysine 6 residue of human CHMP2B, a key ESCRT-III component, at the ICB, impacting the dynamic relocation of CHMP2B to sites of abscission. SMYD2 loss-of-function (genetically or pharmacologically) causes CHMP2B hypomethylation, delayed CHMP2B polymerization and delayed abscission. This is phenocopied by CHMP2B lysine 6 mutants that cannot be methylated. Conversely, SMYD2 gain-of-function causes CHMP2B hypermethylation and accelerated abscission, specifically in cells undergoing cytokinetic challenges, thereby bypassing the abscission checkpoint. Additional experiments highlight the importance of CHMP2B methylation beyond cytokinesis, namely during ESCRT-III-mediated HIV-1 budding. We propose that lysine methylation signaling fine-tunes the ESCRT-III machinery to regulate the timing of cytokinetic abscission and other ESCRT-III dependent functions.

Spherical Nucleic Acid-Mediated Spatial Matching-Guided Nonenzymatic DNA Circuits for the Prediction and Prevention of Malignant Tumor Invasion

Detection of intracellular miRNAs, especially sensitive imaging of in vivo miRNAs, is vital to the precise prediction and timely prevention of tumorgenesis but remains a technical challenge in terms of nuclease resistance and signal amplification. Here, we demonstrate a gold nanoparticle-based spherical nucleic acid-mediated spatial matching-guided nonenzymatic DNA circuit (SSDC) for efficient screening of intracellular miRNAs and, in turn, finding cancerous tissues in living organisms before the appearance of clinical symptoms. Due to the substantially enhanced nuclease resistance, the false positive signal is avoided even in a complex biological medium. Target miRNA can straighten out the hairpin DNA probe to be linear, allowing the probe to penetrate into the internal region of a core/shell DNA-functionalized signal nanoampfilier and initiate a strand displacement reaction, generating an amplified fluorescence signal. The detection limit is as low as 17 pM, and miRNA imaging is in good accordance with the gold standard polymerase chain reaction method. The ability to image intracellular miRNAs is substantially superior to that of conventional fluorescence in situ hybridization techniques, making in vivo SSDC-based imaging competent for the precise prediction of tumorigenesis. By intratumoral chemotherapy guided by SSDC-based imaging, tumorigenesis and progression are efficiently controlled before the onset of clinical symptoms.

SMYD4 monomethylates PRMT5 and forms a positive feedback loop to promote hepatocellular carcinoma progression

Both lysine and arginine methyltransferases are thought to be promising therapeutic targets for malignant tumors, yet how these methyltransferases function in malignant tumors, especially hepatocellular carcinoma (HCC), has not been fully elucidated. Here, we reported that SMYD4, a lysine methyltransferase, acts as an oncogene in HCC. SMYD4 was highly upregulated in HCC and promoted HCC cell proliferation and metastasis. Mechanistically, PRMT5, a well-known arginine methyltransferase, was identified as a SMYD4-binding protein. SMYD4 monomethylated PRMT5 and enhanced the interaction between PRMT5 and MEP50, thereby promoting the symmetrical dimethylation of H3R2 and H4R3 on the PRMT5 target gene promoter and subsequently activating DVL3 expression and inhibiting expression of E-cadherin, RBL2, and miR-29b-1-5p. Moreover, miR-29b-1-5p was found to inversely regulate SMYD4 expression in HCC cells, thus forming a positive feedback loop. Furthermore, we found that the oncogenic effect of SMYD4 could be effectively suppressed by PRMT5 inhibitor in vitro and in vivo. Clinically, high coexpression of SMYD4 and PRMT5 was associated with poor prognosis of HCC patients. In summary, our study provides a model of crosstalk between lysine and arginine methyltransferases in HCC and highlights the SMYD4-PRMT5 axis as a potential therapeutic target for the treatment of HCC.

Utilizing non-coding RNA-mediated regulation of ATP binding cassette (ABC) transporters to overcome multidrug resistance to cancer chemotherapy

Multidrug resistance (MDR) is one of the primary factors that produces treatment failure in patients receiving cancer chemotherapy. MDR is a complex multifactorial phenomenon, characterized by a decrease or abrogation of the efficacy of a wide spectrum of anticancer drugs that are structurally and mechanistically distinct. The overexpression of the ATP-binding cassette (ABC) transporters, notably ABCG2 and ABCB1, are one of the primary mediators of MDR in cancer cells, which promotes the efflux of certain chemotherapeutic drugs from cancer cells, thereby decreasing or abolishing their therapeutic efficacy. A number of studies have suggested that non-coding RNAs (ncRNAs), particularly microRNAs (miRNAs), long non-coding RNAs (lncRNAs) and circular RNAs (circRNAs), play a pivotal role in mediating the upregulation of ABC transporters in certain MDR cancer cells. This review will provide updated information about the induction of ABC transporters due to the aberrant regulation of ncRNAs in cancer cells. We will also discuss the measurement and biological profile of circulating ncRNAs in various body fluids as potential biomarkers for predicting the response of cancer patients to chemotherapy. Sequence variations, such as alternative polyadenylation of mRNA and single nucleotide polymorphism (SNPs) at miRNA target sites, which may indicate the interaction of miRNA-mediated gene regulation with genetic variations to modulate the MDR phenotype, will be reviewed. Finally, we will highlight novel strategies that could be used to modulate ncRNAs and circumvent ABC transporter-mediated MDR.

Integration analysis of PLAUR as a sunitinib resistance and macrophage related biomarker in ccRCC, an in silicon and experimental study

Sunitinib remains the preferred systemic treatment option for specific patients with advanced RCC who are ineligible for immune therapy. However, it's essential to recognize that Sunitinib fails to elicit a favourable response in all patients. Moreover, most patients eventually develop resistance to Sunitinib. Therefore, identifying new targets associated with Sunitinib resistance is crucial. Utilizing multiple datasets from public cohorts, we conducted an exhaustive analysis and identified a total of 8 microRNAs and 112 mRNAs displaying significant expression differences between Sunitinib responsive and resistant groups. A particular set of six genes, specifically NIPSNAP1, STK40, SDC4, NEU1, TBC1D9, and PLAUR, were identified as highly significant via WGCNA. To delve deeper into the resistance mechanisms, we performed additional investigations using cell, molecular, and flow cytometry tests. These studies confirmed PLAUR's pivotal role in fostering Sunitinib resistance, both in vitro and in vivo. Our findings suggest that PLAUR could be a promising therapeutic target across various cancer types. In conclusion, this investigation not only uncovers vital genes and microRNAs associated with Sunitinib resistance in RCC but also introduces PLAUR as a prospective therapeutic target for diverse cancers. The outcomes contribute to advancing personalized healthcare and developing superior therapeutic strategies.Communicated by Ramaswamy H. Sarma.

Potential therapies targeting nuclear metabolic regulation in cancer

The interplay between genetic alterations and metabolic dysregulation is increasingly recognized as a pivotal axis in cancer pathogenesis. Both elements are mutually reinforcing, thereby expediting the ontogeny and progression of malignant neoplasms. Intriguingly, recent findings have highlighted the translocation of metabolites and metabolic enzymes from the cytoplasm into the nuclear compartment, where they appear to be intimately associated with tumor cell proliferation. Despite these advancements, significant gaps persist in our understanding of their specific roles within the nuclear milieu, their modulatory effects on gene transcription and cellular proliferation, and the intricacies of their coordination with the genomic landscape. In this comprehensive review, we endeavor to elucidate the regulatory landscape of metabolic signaling within the nuclear domain, namely nuclear metabolic signaling involving metabolites and metabolic enzymes. We explore the roles and molecular mechanisms through which metabolic flux and enzymatic activity impact critical nuclear processes, including epigenetic modulation, DNA damage repair, and gene expression regulation. In conclusion, we underscore the paramount significance of nuclear metabolic signaling in cancer biology and enumerate potential therapeutic targets, associated pharmacological interventions, and implications for clinical applications. Importantly, these emergent findings not only augment our conceptual understanding of tumoral metabolism but also herald the potential for innovative therapeutic paradigms targeting the metabolism-genome transcriptional axis.

Mechanisms of sunitinib resistance in renal cell carcinoma and associated opportunities for therapeutics

Sunitinib is the first-line drug for renal cell carcinoma (RCC) treatment. However, patients who received sunitinib treatment will ultimately develop drug resistance after 6-15 months, creating a huge obstacle to the current treatment of renal cell carcinoma. Therefore, it is urgent to clarify the mechanisms of sunitinib resistance and develop new strategies to overcome it. In this review, the mechanisms of sunitinib resistance in renal cell carcinoma have been summarized based on five topics: activation of bypass or alternative pathway, inadequate drug accumulation, tumour microenvironment, metabolic reprogramming and epigenetic regulation. Furthermore, present and potential biomarkers, as well as potential treatment strategies for overcoming sunitinib resistance in renal cell carcinoma, are also covered.

SMYD2 inhibition-mediated hypomethylation of Ku70 contributes to impaired nonhomologous end joining repair and antitumor immunity

DNA damage repair (DDR) is a double-edged sword with different roles in cancer susceptibility and drug resistance. Recent studies suggest that DDR inhibitors affect immune surveillance. However, this phenomenon is poorly understood. We report that methyltransferase SMYD2 plays an essential role in nonhomologous end joining repair (NHEJ), driving tumor cells adaptive to radiotherapy. Mechanically, in response to DNA damage, SMYD2 is mobilized onto chromatin and methylates Ku70 at lysine-74, lysine-516, and lysine-539, leading to increased recruitment of Ku70/Ku80/DNA-PKcs complex. Knockdown of SMYD2 or its inhibitor AZ505 results in persistent DNA damage and improper repair, which sequentially leads to accumulation of cytosolic DNA, and activation of cGAS-STING pathway and triggers antitumor immunity via infiltration and activation of cytotoxic CD8⁺ T cells. Our study reveals an unidentified role of SMYD2 in regulating NHEJ pathway and innate immune responses, suggesting that SMYD2 is a promising therapeutic target for cancer treatment.

Non-coding RNAs in renal cell carcinoma: Implications for drug resistance

Renal cell carcinoma (RCC) represents a malignant tumor of the urinary system. Individuals with early-stage RCC could be cured by surgical treatment, but a considerable number of cases of advanced RCC progress to drug resistance. Recently, numerous reports have demonstrated that a variety of non-coding RNAs (ncRNAs) contribute to tumor occurrence and development. ncRNAs can act as oncogenic or tumor suppressor genes to regulate proliferation, migration, drug resistance and other processes in RCC cells through a variety of signaling pathways. Considering the lack of treatment options for advanced RCC after drug resistance, ncRNAs may be a good choice as biomarkers of drug resistance in RCC and targets to overcome drug resistance. In this review, we discussed the effects of ncRNAs on drug resistance in RCC and the great potential of ncRNAs as a biomarker of or a new therapeutic method in RCC.

Understanding and targeting resistance mechanisms in cancer

Resistance to cancer therapies has been a commonly observed phenomenon in clinical practice, which is one of the major causes of treatment failure and poor patient survival. The reduced responsiveness of cancer cells is a multifaceted phenomenon that can arise from genetic, epigenetic, and microenvironmental factors. Various mechanisms have been discovered and extensively studied, including drug inactivation, reduced intracellular drug accumulation by reduced uptake or increased efflux, drug target alteration, activation of compensatory pathways for cell survival, regulation of DNA repair and cell death, tumor plasticity, and the regulation from tumor microenvironments (TMEs). To overcome cancer resistance, a variety of strategies have been proposed, which are designed to enhance the effectiveness of cancer treatment or reduce drug resistance. These include identifying biomarkers that can predict drug response and resistance, identifying new targets, developing new targeted drugs, combination therapies targeting multiple signaling pathways, and modulating the TME. The present article focuses on the different mechanisms of drug resistance in cancer and the corresponding tackling approaches with recent updates. Perspectives on polytherapy targeting multiple resistance mechanisms, novel nanoparticle delivery systems, and advanced drug design tools for overcoming resistance are also reviewed.

H3 histone methylation landscape in male urogenital cancers: from molecular mechanisms to epigenetic biomarkers and therapeutic targets

During the last decades, male urogenital cancers (including prostate, renal, bladder and testicular cancers) have become one of the most frequently encountered malignancies affecting all ages. While their great variety has promoted the development of various diagnosis, treatment and monitoring strategies, some aspects such as the common involvement of epigenetic mechanisms are still not elucidated. Epigenetic processes have come into the spotlight in the past years as important players in the initiation and progression of tumors, leading to a plethora of studies highlighting their potential as biomarkers for diagnosis, staging, prognosis, and even as therapeutic targets. Thus, fostering research on the various epigenetic mechanisms and their roles in cancer remains a priority for the scientific community. This review focuses on one of the main epigenetic mechanisms, namely, the methylation of the histone H3 at various sites and its involvement in male urogenital cancers. This histone modification presents a great interest due to its modulatory effect on gene expression, leading either to activation (e.g., H3K4me3, H3K36me3) or repression (e.g., H3K27me3, H3K9me3). In the last few years, growing evidence has demonstrated the aberrant expression of enzymes that methylate/demethylate histone H3 in cancer and inflammatory diseases, that might contribute to the initiation and progression of such disorders. We highlight how these particular epigenetic modifications are emerging as potential diagnostic and prognostic biomarkers or targets for the treatment of urogenital cancers.

The role of histone methylation in renal cell cancer: an update

Renal cell carcinoma accounts for 2-3% of all cancers. It is difficult to diagnose early. Recently, genome-wide studies have identified that histone methylation was one of the functional classes that is most frequently dysregulated in renal cell cancer. Mutation or mis-regulation of histone methylation, methyltransferases, demethylases are associated with gene expression and tumor progression in renal cell cancer. Herein, we summarize histone methylations, demethylases and their alterations and mechanisms in renal cell cancer.

Targeting Epigenetic Changes Mediated by Members of the SMYD Family of Lysine Methyltransferases

A comprehensive understanding of the mechanisms involved in epigenetic changes in gene expression is essential to the clinical management of diseases linked to the SMYD family of lysine methyltransferases. The five known SMYD enzymes catalyze the transfer of donor methyl groups from S-adenosylmethionine (SAM) to specific lysines on histones and non-histone substrates. SMYDs family members have distinct tissue distributions and tissue-specific functions, including regulation of development, cell differentiation, and embryogenesis. Diseases associated with SMYDs include the repressed transcription of SMYD1 genes needed for the formation of ion channels in the heart leading to heart failure, SMYD2 overexpression in esophageal squamous cell carcinoma (ESCC) or p53-related cancers, and poor prognosis associated with SMYD3 overexpression in more than 14 types of cancer including breast cancer, colon cancer, prostate cancer, lung cancer, and pancreatic cancer. Given the importance of epigenetics in various pathologies, the development of epigenetic inhibitors has attracted considerable attention from the pharmaceutical industry. The pharmacologic development of the inhibitors involves the identification of molecules regulating both functional SMYD SET (Suppressor of variegation, Enhancer of Zeste, Trithorax) and MYND (Myeloid-Nervy-DEAF1) domains, a process facilitated by available X-ray structures for SMYD1, SMYD2, and SMYD3. Important leads for potential pharmaceutical agents have been reported for SMYD2 and SMYD3 enzymes, and six epigenetic inhibitors have been developed for drugs used to treat myelodysplastic syndrome (Vidaza, Dacogen), cutaneous T-cell lymphoma (Zoinza, Isrodax), and peripheral T-cell lymphoma (Beleodag, Epidaza). The recently demonstrated reversal of SMYD histone methylation suggests that reversing the epigenetic effects of SMYDs in cancerous tissues may be a desirable target for pharmacological development.

Targeting SMYD2 inhibits angiogenesis and increases the efficiency of apatinib by suppressing EGFL7 in colorectal cancer

Angiogenesis is an essential factor affecting the occurrence and development of solid tumors. SET And MYND Domain Containing 2 (SMYD2) serves as an oncogene in various cancers. However, whether SMYD2 is involved in tumor angiogenesis remains unclear. Here, we report that SMYD2 expression is associated with microvessel density in colorectal cancer (CRC) tissues. SMYD2 promotes CRC angiogenesis in vitro and in vivo. Mechanistically, SMYD2 physically interacts with HNRNPK and mediates lysine monomethylation at K422 of HNRNPK, which substantially increases RNA binding activity. HNRNPK acts by binding and stabilizing EGFL7 mRNA. As an angiogenic stimulant, EGFL7 enhances CRC angiogenesis. H3K4me3 maintained by PHF8 mediates the abnormal overexpression of SMYD2 in CRC. Moreover, targeting SMYD2 blocks CRC angiogenesis in tumor xenografts. Treatment with BAY-598, a functional inhibitor of SMYD2, can also synergize with apatinib in patient-derived xenografts. Overall, our findings reveal a new regulatory axis of CRC angiogenesis and provide a potential strategy for antiangiogenic therapy.

Effect of miRNA-200b on the proliferation of liver cancer cells via targeting SMYD2/p53 signaling pathway

OBJECTIVES

Our previous study has verified that high level of SET and MYND domain-containing protein 2 (SMYD2) plays an important role in acquiring aggressive ability for liver cancer cells in hepatocellular carcinoma. MiR-200b as a tumor suppressor gene involves in a variety of cancers. This study aims to investigate the correlation between miR-200b and SMYD2 in hepatocellular carcinoma and the underlying mechanism.

METHODS

Firstly, the levels of SMYD2 and miR-200b in hepatocellular carcinoma tissues and matched adjacent non-tumor liver tissues were tested with real-time reverse transcription-polymerase chain reaction (RT-PCR) and Western blotting. Secondly, we evaluated the interaction between miR-200b and SMYD2 using dual-luciferase reporter assay. Thirdly, we elucidated the effect of miR-200b on SMYD2 and its downstream targets p53/CyclinE1. Finally, we silenced SMYD2 in hepatocellular carcinoma cell lines to investigate its effect on tumor proliferation and cell cycle progression, and further confirmed the correlation among SMYD2 and p53/CyclinE1.

RESULTS

Compared with the matched adjacent non-tumor liver tissues, miR-200b was obviously decreased, and SMYD2 was significantly increased in hepatocellular carcinoma (both P<0.05). Spearman's rank correlation revealed that miR-200b expression was negatively correlated with SMYD2 (P<0.01). Computer algorithm and dual-luciferase reporter assay revealed that miR-200b directly targeted and suppressed SMYD2 in HEK 293T cells. The down-regulated miR-200b expression promoted hepatoma cell proliferation (P<0.05) and increased SMYD2 expression(P<0.01), while the up-regulated expression of miR-200b had an opposite effect. The knockdown of SMYD2 suppressed the proliferation of MHCC-97L cells (P<0.01), down-regulated CyclinE1, and up-regulated p53 expression (both P<0.05).

CONCLUSIONS

MiR-200b is involved in hepatocellular carcinoma progression via targeting SMYD2 and regulating SMYD2/p53/CyclinE1 signaling pathway and may be used as a potential target for hepatocellular carcinoma treatment.

P-glycoprotein and cancer: what do we currently know?

Acquired resistance during cancer treatment is unfortunately a frequent event. There are several reasons for this, including the ability of the ATP-binding cassette transporters (ABC transporters), which are integral membrane proteins, to export chemotherapeutic molecules from the interior of the tumor cells. One important member of this family is the protein known as Permeability Glycoprotein (P-Glycoprotein, P-gp or ABCB1). Its clinical relevance relies mainly on the fact that the inhibition of P-gp and other ABC transporters could result in the reversal of the multidrug resistance (MDR) phenotype in some patients. Recently, other roles apart from being a key player in MDR, have emerged for P-gp. Therefore, this review discusses the relationship between P-gp and MDR, in addition to the possible role of this protein as a biomarker in cancer.

Protein tyrosine kinase inhibitor resistance in malignant tumors: molecular mechanisms and future perspective

Protein tyrosine kinases (PTKs) are a class of proteins with tyrosine kinase activity that phosphorylate tyrosine residues of critical molecules in signaling pathways. Their basal function is essential for maintaining normal cell growth and differentiation. However, aberrant activation of PTKs caused by various factors can deviate cell function from the expected trajectory to an abnormal growth state, leading to carcinogenesis. Inhibiting the aberrant PTK function could inhibit tumor growth. Therefore, tyrosine kinase inhibitors (TKIs), target-specific inhibitors of PTKs, have been used in treating malignant tumors and play a significant role in targeted therapy of cancer. Currently, drug resistance is the main reason for limiting TKIs efficacy of cancer. The increasing studies indicated that tumor microenvironment, cell death resistance, tumor metabolism, epigenetic modification and abnormal metabolism of TKIs were deeply involved in tumor development and TKI resistance, besides the abnormal activation of PTK-related signaling pathways involved in gene mutations. Accordingly, it is of great significance to study the underlying mechanisms of TKIs resistance and find solutions to reverse TKIs resistance for improving TKIs efficacy of cancer. Herein, we reviewed the drug resistance mechanisms of TKIs and the potential approaches to overcome TKI resistance, aiming to provide a theoretical basis for improving the efficacy of TKIs.

STUB1-SMYD2 Axis Regulates Drug Resistance in Glioma cells

SET and MYND domain-containing protein 2 (SMYD2) is an important epigenetic regulator that methylates histone and non-histone proteins. The study aimed to investigate the oncogenic role of SMYD2 in gliomas and explore its degradation mechanism induced by cisplatin. Tumor tissue microarray of 441 patients with glioma was collected for SMYD2 immunohistochemical staining. Kaplan-Meier survival curves were constructed using the overall survival values. mRNA-sequencing analysis was performed for understanding the downstream mechanisms mediated by SMYD2. The half-inhibitory concentrations (IC50) of temozolomide and cisplatin in AZ505-treated and control cells were calculated. The potential E3 ubiquitin ligase of SMYD2 was predicted in UbiBrowser and confirmed by a knockdown test. The effect of SMYD2 and its E3 ligase on apoptosis and migration of glioma cells was determined via cell-function assays. High SMYD2 expression correlated with a high WHO stage (P = 0.004) and a low survival probability (P = 0.012). The inhibition of SMYD2 suppressed the process of epithelial to mesenchymal transition (EMT) by downregulating the expression of Collagen 1A1 (COL1A1). AZ505 treatment significantly increased the drug sensitivity of glioma cells. SMYD2 expression was markedly reduced by cisplatin treatment via STIP1 Homology And U-Box Containing Protein 1 (STUB1)-mediated degradation. The knockdown of STUB1 could partly reverse the cell function impairment induced by cisplatin. Our findings suggested that SMYD2 could be a potential drug target for the treatment of gliomas, and STUB1-mediated degradation of SMYD2 plays an important role in reversing chemotherapy resistance in patients with gliomas.

Protein Lysine Methyltransferase SMYD2: A Promising Small Molecule Target for Cancer Therapy

In epigenetic research, the abnormality of protein methylation modification is closely related to the occurrence and development of tumors, which stimulates the interest of researchers in protein methyltransferase research and the efforts to develop corresponding specific small molecule inhibitors. Currently, the protein lysine methyltransferase SMYD2 has been identified as a promising new small molecule target for cancer therapy. But its biological functions have not been fully studied and relatively few inhibitors have been reported, thus this field needs to be further explored. This perspective provides a comprehensive and systematic review of the available resources in this field, including its research status, biological structure, related substrates and methylation mechanisms, and research status of inhibitors. In addition, this perspective elaborates in detail the current challenges in this field, our insights into what needs to be done next, rational drug design of novel SMYD2 inhibitors, and foreseeable development directions in the future.

Oleocanthal Attenuates Metastatic Castration-Resistant Prostate Cancer Progression and Recurrence by Targeting SMYD2

Simple Summary

The Mediterranean, extra-virgin-olive-oil-rich diet ingredient S-(-)-oleocanthal (OC) has emerged as a potential inhibitor for the growth and relapse of the most aggressive prostate cancer type. This effect is mediated through suppression of important enzyme, SMYD2, that drives the activation of several downstream protein effectors. OC treatments reduced SMYD2 downstream substrates, which are critical for prostate cancer growth and relapse. OC is more advantageous than other reported SMYD2 inhibitors because it has shown potent anticancer activity in animal models. OC’s anti-prostate-cancer effect was prominent compared with some standard drugs currently used to control prostate cancer. OC is a potential, novel natural compound appropriate for immediate use by prostate cancer patients and survivors as a nutraceutical or dietary supplement product.

Abstract

Metastatic castration-resistant prostate cancer (mCRPC) is the most aggressive prostate cancer (PC) phenotype. Cellular lysine methylation is driven by protein lysine methyltransferases (PKMTs), such as those in the SET- and MYND-containing protein (SMYD) family, including SMYD2 methylate, and several histone and non-histone proteins. SMYD2 is dysregulated in metastatic PC patients with high Gleason score and shorter survival. The Mediterranean, extra-virgin-olive-oil-rich diet ingredient S-(-)-oleocanthal (OC) inhibited SMYD2 in biochemical assays and suppressed viability, migration, invasion, and colony formation of PC-3, CWR-R1ca, PC-3M, and DU-145 PC cell lines with IC₅₀ range from high nM to low µM. OC’s in vitro antiproliferative effect was comparable to standard anti-PC chemotherapies or hormone therapies. A daily, oral 10 mg/kg dose of OC for 11 days effectively suppressed the progression of the mCRPC CWR-R1ca cells engrafted into male nude mice. Daily, oral OC treatment for 30 days suppressed tumor locoregional and distant recurrences after the primary tumors’ surgical excision. Collected OC-treated animal tumors showed marked SMYD2 reduction. OC-treated mice showed significant serum PSA reduction. For the first time, this study showed SMYD2 as novel molecular target in mCRPC, and OC emerged as a specific SMYD2 lead inhibitor. OC prevailed over previously reported SMYD2 inhibitors, with validated in vivo potency and high safety profile, and, therefore, is proposed as a novel nutraceutical for mCRPC progression and recurrence control.

Overexpression of MCAM induced by SMYD2-H3K36me2 in breast cancer stem cell properties

BACKGROUND

Melanoma cell adhesion molecule (MCAM) is highly expressed in various malignancies. However, studies on the effects of MCAM on stemness of cancer stem cells are limited. Here, we aimed to explore the relationship between MCAM and stem cell phenotype in breast cancer (BC).

METHODS

We analyzed the genes differentially expressed in BC from the oncomine database, followed by TCGA-BRCA database validation. We then used gene set enrichment analysis to analyze the signaling pathways enriched to the relevant genes, followed by loss-of-function experiments to analyze the role of MCAM in the growth of BC cells and the maintenance of stem cell properties. We analyzed the cause for the MCAM overexpression using ChIP-seq and clarified the upstream mechanism by constructing SE-Deleted cells. Finally, the role of SMYD2 in the growth of BC cells and the maintenance of stem cell properties were verified by rescue experiments.

RESULTS

MCAM was significantly overexpressed in BC, which predicted somber prognosis in patients. Knockdown of MCAM drastically hindered the growth and metastasis of BC cells in vitro and in vivo. Subsequently, the MCAM promoter was observed to have significant H3K36me2 modification and that SMYD2 could significantly promote the expression of MCAM. In addition, further overexpression of SMYD2 in cells with MCAM knockdown increased MCAM expression and promoted the growth as well as stemness of BC cells.

CONCLUSION

SMYD2 can elevate the expression of MCAM by promoting its H3K36me2 modification, which in turn expedites the growth and stem cell properties of BC cells.

SMYD5 acts as a potential biomarker for hepatocellular carcinoma

Determining the prognosis of patients remains a challenge due to the phenotypic and molecular diversities of hepatocellular carcinomas (HCC). We aimed to evaluate the role of SMYD5 in HCC. Wilcoxon signed-rank test and logistic regression analyzed the relationship between clinical pathologic features and SMYD5. We found that increased expression of SMYD5 in HCC was closely associated with high histologic grade, stage, T stage and nodal stage. Kaplan-Meier method, Cox regression, univariate analysis and multivariate analysis detected overall survival of TCGA-HCC patients. It turned out that high expression of SMYD5 predicted a worse prognosis in HCC. Gene Set Enrichment Analysis (GSEA) was applied via TCGA data set, which indicated that complement and coagulation cascades, fatty acid metabolism, primary bile acid biosynthesis, drug metabolism cytochrome P450, PPAR signaling pathway and retinol metabolism were differentially enriched in SMYD5 high expression phenotype. Interestingly, we proved that SMYD5 upregulation in HCC cells was induced by promoter hypo-methylation. Moreover, functional experiments demonstrated that SMYD5 silencing abrogated cell proliferation, migration and invasion and enhanced paclitaxel sensitivity in HCC. All findings implied that SMYD5 might be an underlying biomarker for prognosis and treatment of HCC.

LINC01605, regulated by the EP300-SMYD2 complex, potentiates the binding between METTL3 and SPTBN2 in colorectal cancer

Background

Colorectal cancer (CC) is one of the major contributors to tumor-related death worldwide, and its main cause of death is distant metastasis. Dysregulation of long non-coding RNA (lncRNA) LINC01605 has been implicated in CC. However, its role in metastasis of CC remains elusive. The goal of the study is to uncover the biological function and molecular mechanism of LINC01605 in CC.

Methods

The differentially expressed lncRNAs were first screened from GSE97300, GSE84983, GSE110715, GSE70880, and GSE75970 microarrays. The correlation between the expression of LINC01605 and the clinical phenotypes of enrolled CC patients (n = 134) was subsequently analyzed. The upstream and downstream regulatory mechanisms of LINC01605 in CC were identified through bioinformatics and RNA-seq analyses. Finally, the effects of related factors on CC cell growth and metastasis were confirmed through functional validation experiments.

Results

LINC01605, significantly highly expressed in CC, was a prognostic factor for patients with CC. Functional experiments revealed that LINC01605 knockdown inhibited the proliferatory and metastatic potential of CC cells in vitro and in vivo. Moreover, LINC01605 was regulated by SMYD2-EP300-mediated modifications of histone H3K4me3 as well as H3K27ac. LINC01605 was found to bind to METTL3 and promote the m6A modification of SPTBN2 mRNA, thereby facilitating the translation of SPTBN2.

Conclusions

Overexpression of LINC01605, regulated by SMYD2-EP300-mediated H3K27ac and H3K4me3 modifications, bound to METTL3 protein to promote m6A modification of SPTBN2 mRNA, leading to the development of CC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-02180-8.

Novel insights into SMYD2 and SMYD3 inhibitors: from potential anti-tumoural therapy to a variety of new applications

The revelance of the epigenetic regulation of cancer led to the design and testing of many drugs targeting epigenetic modifiers. The Su(Var)3-9, Enhancer-of-zeste and Trithorax (SET) and myeloid, Nervy, and DEAF-1 (MYND) domain-containing protein 2 (SMYD2) and 3 (SMYD3) are methyltransferases which act on histone and non-histone proteins to promote tumorigenesis in many cancer types. In addition to their oncogenic roles, SMYD2 and SMYD3 are involved in many other physiopathological conditions. In this review we will focus on the advances made in the last five years in the field of pharmacology regarding drugs targeting SMYD2 (such as LLY-507 or AZ505) and SMYD3 (such as BCI-121 or EPZ031686) and their potential cellular and molecular mechanisms of action and application in anti-tumoural therapy and/or against other diseases.

Critical roles of SMYD2 lysine methyltransferase in mediating renal fibroblast activation and kidney fibrosis

SET and MYND domain protein 2 (SMYD2) is a lysine methyltransferase that mediates histone H3 lysine 36 trimethylation (H3K36me3) and acts as a regulator of tumorgenesis and cystic growth. However, its role in renal fibrosis remains unknown. In this study, we found that SMYD2 was highly expressed in the murine kidney of renal fibrosis induced by unilateral ureteral obstruction, and primarily located in interstitial fibroblasts and renal tubular epithelial cells. Pharmacological inhibition of SMYD2 with AZ505, a highly selective inhibitor of SMYD2, protected against renal fibrosis and inhibited activation/proliferation of renal interstitial fibroblasts and conversion of epithelial cells to a profibrotic phenotype in this model. In cultured renal interstitial fibroblasts, treatment with AZ505 or silencing of SMYD2 by specific siRNA also inhibited serum- or TGF-β1-induced activation and proliferation of renal interstitial fibroblasts. Mechanistic studies showed that SMYD2 inhibition reduced phosphorylation of several profibrotic signaling molecules, including Smad3, extracellular signal-regulated kinase 1/2, AKT, signal transducer and activator of transcription-3 and nuclear factor-κB in both injured kidney and cultured renal fibroblasts. AZ505 was also effective in suppressing renal expression of Snail and Twist, two transcriptional factors that mediate renal partial epithelial-mesenchymal transition and fibrosis. Conversely, AZ505 treatment prevented downregulation of Smad7, a renoprotective factor in vivo and in vitro. These results indicate that SMYD2 plays a critical role in mediating conversion of epithelial cells to a profibrotic phenotype, renal fibroblast activation and renal fibrogenesis, and suggest that SMYD2 may be a potential target for the treatment of chronic fibrosis in kidney disease.

SMYD2 suppresses p53 activity to promote glucose metabolism in cervical cancer

Reprogrammed energy metabolism, especially the Warburg effect, is emerged as a hallmark of cancer. The protein lysine methyltransferase SMYD2 functions as an oncogene and is implicated in various malignant phenotypes of human cancers. However, the role of SMYD2 in tumor metabolism is still largely unknown. Here, we report that SMYD2 is highly expressed in human cervical cancer and its aberrant expression is linked to a poor prognosis. Bioinformatic analysis revealed a novel link between SMYD2 expression and aerobic glycolysis. Through loss-of-function experiments, we demonstrated that SMYD2 knockdown or inhibition induced a metabolic shift from aerobic glycolysis to oxidative phosphorylation, as evidenced by glucose uptake, lactate production, extracellular acidification, and the oxygen consumption rate. In contrast, SMYD2 overexpression promoted glycolytic metabolism in cervical cancer cells. Moreover, SMYD2 was required for tumor growth in cervical cancer and this oncogenic activity was largely glycolysis-dependent. Mechanistically, SMYD2 altered the methylation status of p53 and inhibited its transcriptional activity. Genetic silencing of p53 largely abrogated the effects of SMYD2 in promoting aerobic glycolysis. Taken together, our findings reveal a novel function of SMYD2 in regulating the Warburg effect in cervical cancer.

Silencing of the chemokine CXC receptor 4 (CXCR4) hampers cancer progression and increases cisplatin (DDP)-sensitivity in clear cell renal cell carcinoma (ccRCC)

Aberrant expression of the chemokine CXC receptor 4 (CXCR4) is closely associated with cancer progression and drug-resistance in multiple cancers, and we first investigated the role of CXCR4 in regulating cancer pathogenesis and cisplatin (DDP)-resistance in clear cell renal cell carcinoma (ccRCC) in the present study. Here, we identified that CXCR4 acted as an oncogene to promote cancer progression and genetically silencing of CXCR4 increased cisplatin (DDP)-sensitivity in ccRCC in vitro and in vivo. Functionally, analysis from the clinical and cellular data indicated that CXCR4 was significantly upregulated in ccRCC tissues and cells, compared to their normal counterparts. Next, the loss-of-function experiments validated that knock-down of CXCR4 suppressed cell proliferation, invasion, migration and epithelial-mesenchymal transition (EMT) in ccRCC cells, while CXCR4 overexpression had opposite effects on the above cellular functions. Consistently, the xenograft tumor-bearing mice models were established, and the results supported that knock-down of CXCR4 inhibited tumor growth and the expression levels of Ki67 protein in vivo. In addition, the ccRCC cells were exposed to DDP treatment, and we surprisingly found that upregulation of CXCR4 increased DDP-resistance in ccRCC cells, and conversely, CXCR4 ablation sensitized ccRCC cells to DDP stimulation. Taken together, we concluded that CXCR4 ablation hindered cancer progression and enhanced DDP-sensitivity in ccRCC, and the present study identified a novel therapeutic biomarker for ccRCC.

Histone H3K4 Methyltransferases as Targets for Drug-Resistant Cancers

The KMT2 (MLL) family of proteins, including the major histone H3K4 methyltransferase found in mammals, exists as large complexes with common subunit proteins and exhibits enzymatic activity. SMYD, another H3K4 methyltransferase, and SET7/9 proteins catalyze the methylation of several non-histone targets, in addition to histone H3K4 residues. Despite these structural and functional commonalities, H3K4 methyltransferase proteins have specificity for their target genes and play a role in the development of various cancers as well as in drug resistance. In this review, we examine the overall role of histone H3K4 methyltransferase in the development of various cancers and in the progression of drug resistance. Compounds that inhibit protein-protein interactions between KMT2 family proteins and their common subunits or the activity of SMYD and SET7/9 are continuously being developed for the treatment of acute leukemia, triple-negative breast cancer, and castration-resistant prostate cancer. These H3K4 methyltransferase inhibitors, either alone or in combination with other drugs, are expected to play a role in overcoming drug resistance in leukemia and various solid cancers.

A Review of Recent Research on the Role of MicroRNAs in Renal Cancer

Renal cell carcinoma (RCC) is a most common type of urologic neoplasms; it accounts for 3% of malignant tumors, with high rates of relapse and mortality. The most common types of renal cancer are clear cell carcinoma (ccRCC), papillary renal cell carcinoma (pRCC), and chromophobe renal carcinoma (chRCC), which account for 90%, 6–15%, and 2–5%, respectively, of all renal malignancies. Although surgical resection, chemotherapy, and radiotherapy are the most common treatment method for those diseases, their effects remain dissatisfactory. Furthermore, recent research shows that the treatment efficacy of checkpoint inhibitors in advanced RCC patients is widely variable. Hence, patients urgently need a new molecular biomarker for early diagnosis and evaluating the prognosis of RCC. MicroRNAs (miRNAs) belong to a family of short, non-coding RNAs that are highly conserved, have long half-life evolution, and post-transcriptionally regulate gene expression; they have been predicted to play crucial roles in tumor metastasis, invasion, angiogenesis, proliferation, apoptosis, epithelial-mesenchymal transition, differentiation, metabolism, cancer occurrence, and treatment resistance. Although some previous papers demonstrated that miRNAs play vital roles in renal cancer, such as pathogenesis, diagnosis, and prognosis, the roles of miRNAs in kidney cancer are still unclear. Therefore, we reviewed studies indexed in PubMed from 2017 to 2020, and found several studies suggesting that there are more than 82 miRNAs involved in renal cancers. The present review describes the current status of miRNAs in RCC and their roles in progression, diagnosis, therapy targeting, and prognosis of RCC.

Long non-coding RNAs in the doxorubicin resistance of cancer cells

Chemotherapy is the main treatment used for cancer patients failing surgery. Doxorubicin (DOX) is a well-known chemotherapeutic agent capable of suppressing proliferation in cancer cells and triggering apoptosis via inhibiting topoisomerase II activity and producing DNA breaks. This activity of DOX restrains mitosis and cell cycle progression. However, frequent application of DOX results in the emergence of resistance in the cancer cells. It seems that genetic and epigenetic factors can provide DOX resistance of cancer cells. Long non-coding RNAs (lncRNAs) are a subcategory of non-coding RNAs with role in the regulation of several cellular processes such as proliferation, migration, differentiation and apoptosis. LncRNA dysregulation has been associated with chemoresistance, and this profile occurs upon DOX treatment of cancer. In the present review, we focus on the role of lncRNAs in mediating DOX resistance and discuss the molecular pathways and mechanisms. LncRNAs can drive DOX resistance via activating pathways such as NF-κB, PI3K/Akt, Wnt, and FOXC2. Some lncRNAs can activate protective autophagy in response to the stress caused by DOX, which mediates resistance. In contrast, there are other lncRNAs involved in the sensitivity of cancer cells to DOX, such as GAS5, PTCSC3 and FENDRR. Some anti-tumor agents such as polydatin can regulate the expression of lncRNAs, enhancing DOX sensitivity. Overall, lncRNAs are potential players in DOX resistance, and their identification and targeting are of importance in chemosensitivity. Furthermore, these findings can be translated into clinical for treatment of cancer patients.

PRMT1 is a novel molecular therapeutic target for clear cell renal cell carcinoma

Background and Objective: Epigenetic alterations are common events in clear cell renal cell carcinoma (ccRCC), and protein arginine methyltransferase 1 (PRMT1) is an important epigenetic regulator in cancers. However, its role in ccRCC remains unclear.

Methods: We investigated PRMT1 expression level and its correlations to clinicopathological factors and prognosis in ccRCC patients based on ccRCC tissue microarrays (TMAs). Genetic knockdown and pharmacological inhibition using a novel PRMT1 inhibitor DCPT1061 were performed to investigate the functional role of PRMT1 in ccRCC proliferation. Besides, we confirmed the antitumor effect of PRMT1 inhibitor DCPT1061 in ccRCC cell-derived tumor xenograft (CDX) models as well as patient-derived tumor xenograft (PDX) models.

Results: We found PRMT1 expression was remarkably upregulated in tumor tissues and associated with poor pathologic characters and outcomes of ccRCC patients. Furthermore, genetic knockdown and pharmacological inhibition of PRMT1 by a novel potent inhibitor DCPT1061 dramatically induced G1 cell cycle arrest and suppressed ccRCC cell growth. Mechanistically, RNA sequencing and further validation identified Lipocalin2 (LCN2), a secreted glycoprotein implicated in tumorigenesis, as a crucial regulator of ccRCC growth and functional downstream effector of PRMT1. Epigenetic silencing of LCN2 autocrine secretion by PRMT1 deficiency decreased downstream p-AKT, leading to reduced p-RB and cell growth arrest through the neutrophil gelatinase associated lipocalin receptor (NGALR). Moreover, PRMT1 inhibition by DCPT1061 not only inhibited tumor growth but also sensitized ccRCC to sunitinib treatment in vivo by attenuating sunitinib-induced upregulation of LCN2-AKT-RB signaling.

Conclusion: Taken together, our study revealed a PRMT1-dependent epigenetic mechanism in the control of ccRCC tumor growth and drug resistance, indicating PRMT1 may serve as a promising target for therapeutic intervention in ccRCC patients.

The role of non-coding RNAs in ABC transporters regulation and their clinical implications of multidrug resistance in cancer

INTRODUCTION

Multi-drug resistance (MDR) is a hindrance toward the successful treatment of cancers. The primary mechanism that gives rise to acquired chemoresistance is the overexpression of adenosine triphosphate-binding cassette (ABC) transporters. The dysregulation of non-coding RNAs (ncRNAs) is a widely concerned reason contributing to this phenotype.

AREAS COVERED

In this review, we describe the role of intracellular and exosomal ncRNAs including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) in ABC transporters-induced tumor MDR. Meanwhile, we will introduce the potential therapeutic strategies which reverse MDR in terms of reducing the expression of ABC transporters via targeting ncRNAs, like nucleic acid delivery with nanoparticles as well as miRNAs-targeted small molecular compounds.

EXPERT OPINION

The dysregulated ncRNAs-mediated overexpression of ABC transporters in chemo-resistant cancer is not negligible. Finding out the underlying mechanism may provide a theoretical basis for clinical therapy of cancer MDR, and the emergence of new approaches for gene therapy targeting ncRNAs to suppress ABC transporters makes reversing cancer MDR possible despite its clinical application requires further investigations. Also, the discovered ncRNAs regulating ABC transporters in chemo-resistant cancers are just a tip of the iceberg of the genetic transcripts, especially for circRNAs, which justify more concern.Abbreviations: MDR, multi-drug resistance; ABC, adenosine triphosphate-binding cassette; NcRNAs, non-coding RNAs; MiRNAs, microRNAs; LncRNAs, long non-coding RNAs; CircRNAs, circular RNAs; CeRNAs, competing endogenous RNAs; 3'UTR, 3'-untranslated regions; SLC, solute carrier; ABCB1/MDR1, ABC subfamily B member 1; ABCG2/BCRP, ABC subfamily G member 2; ABCCs/MRPs, ABC subfamily C 1 to 12; DLL1: Delta-like protein 1; DTX, docetaxel; DOX/ADM/ADR, doxorubicin/adriamycin; PTX, paclitaxel; VBL, vinblastine; VCR, vincristine; MTX, methotrexate; CDDP/DDP, cisplatin/cis-diaminedichloroplatinum; OXA/L-OHP, oxaliplatin; TMZ, temozolomide; 5-FU, 5-fluorouracil; MTA, pemetrexed; NSCLC, non-small cell lung carcinoma; HCC, hepatocellular carcinoma; CRC, colorectal carcinoma; RB, retinoblastoma; RCC, renal cell carcinoma; OS, osteosarcoma; PDAC, pancreatic ductal adenocarcinoma; TNBC, triple-negative breast cancer.

Sirtuin 6 regulates the proliferation and survival of clear cell renal cell carcinoma cells via B-cell lymphoma 2

Sirtuin 6 (SIRT6) is a member of the third family of longevity proteins (SIRTs) that is involved in the development of different types of cancer. However, the potential role of SIRT6 in clear cell renal cell carcinoma (ccRCC) and its molecular mechanism have not yet been fully elucidated. Therefore, the present study aimed to investigate the association between SIRT6 and ccRCC, and to further examine the underlying mechanism of its effect on ccRCC proliferation, using bioinformatics analysis, and in vitro and in vivo experiments. The results of the present study demonstrated that SIRT6 was upregulated in ccRCC tissues. In addition, bioinformatics analysis revealed that high SIRT6 expression was closely associated with poor prognosis of patients with ccRCC. In vitro experiments demonstrated that silencing SIRT6 expression in ccRCC-derived 769-P and 786-O cells significantly inhibited their proliferation, migration and invasion. Consistent with these results, in vivo assays demonstrated that SIRT6 knockdown markedly attenuated tumor growth arising from 769-P cells. Furthermore, depletion of SIRT6 enhanced the sensitivity of ccRCC cells to cisplatin. Notably, silencing SIRT6 expression decreased B-cell lymphoma 2 (Bcl-2) expression and increased Bax expression, respectively. Taken together, these results suggest that SIRT6 acts as a proto-oncogene in ccRCC through the augmentation of the Bcl-2-dependent pro-survival pathway, and may be used as a therapeutic target for patients with ccRCC.

Epigenetic Alterations in Renal Cell Cancer With TKIs Resistance: From Mechanisms to Clinical Applications

The appearance of tyrosine kinase inhibitors (TKIs) has been a major breakthrough in renal cell carcinoma (RCC) therapy. Unfortunately, a portion of patients with TKIs resistance experience disease progression after TKIs therapy. Epigenetic alterations play an important role in the development of TKIs resistance. Current evidence suggests that epigenetic alterations occur frequently in RCC patients with poor response to TKIs therapy, and modulation of them could enhance the cytotoxic effect of antitumor therapy. In this review, we summarize the currently known epigenetic alterations relating to TKIs resistance in RCC, focusing on DNA methylation, non-coding RNAs (ncRNAs), histone modifications, and their interactions with TKIs treatment. In addition, we discuss application of epigenetic alteration analyses in the clinical setting to predict prognosis of patients with TKIs treatment, and the potential use of epigenetics-based therapies to surmount TKIs resistance.

SMYD3 promotes colon adenocarcinoma (COAD) progression by mediating cell proliferation and apoptosis

Colon adenocarcinoma (COAD) is a type of common malignant tumor originating in the digestive tract. Recently, targeted therapy has had significant effects on the treatment of COAD. However, more effective molecular targets need to be developed. SET and MYND domain-containing protein 3 (SMYD3) is a type of methyltransferase which methylates histone and non-histone proteins. The effects of SMYD3 on cancer progression and metastasis have been widely revealed. However, its possible role in COAD remains unclear. The current study demonstrated that SMYD3 expression was upregulated in human COAD tissues via analyzing the The Cancer Genome Atlas (TCGA) database and the immunohistochemical assays. Furthermore, the expression of SMYD3 was correlated with prognosis and tumor stage (P=0.038) in patients with COAD. Colony formation, MTT, FCM assays and animal assays indicated SMYD3 affected the proliferation, apoptosis and the cell cycle of COAD cells in vitro and promoted tumor growth in mice in vivo. In summary, the results demonstrated the effects of SMYD3 on COAD progression and we hypothesized that SMYD3 is a novel molecular target for COAD treatment.

Epitranscriptomics and epiproteomics in cancer drug resistance: therapeutic implications

Drug resistance is a major hurdle in cancer treatment and a key cause of poor prognosis. Epitranscriptomics and epiproteomics are crucial in cell proliferation, migration, invasion, and epithelial–mesenchymal transition. In recent years, epitranscriptomic and epiproteomic modification has been investigated on their roles in overcoming drug resistance. In this review article, we summarized the recent progress in overcoming cancer drug resistance in three novel aspects: (i) mRNA modification, which includes alternative splicing, A-to-I modification and mRNA methylation; (ii) noncoding RNAs modification, which involves miRNAs, lncRNAs, and circRNAs; and (iii) posttranslational modification on molecules encompasses drug inactivation/efflux, drug target modifications, DNA damage repair, cell death resistance, EMT, and metastasis. In addition, we discussed the therapeutic implications of targeting some classical chemotherapeutic drugs such as cisplatin, 5-fluorouridine, and gefitinib via these modifications. Taken together, this review highlights the importance of epitranscriptomic and epiproteomic modification in cancer drug resistance and provides new insights on potential therapeutic targets to reverse cancer drug resistance.

Mesenchymal stem cells-derived exosomes ameliorate nucleus pulposus cells apoptosis via delivering miR-142-3p: therapeutic potential for intervertebral disc degenerative diseases

Intervertebral disc degeneration (IDD) is the main cause of lower back pain (LBP), and puzzles massive individuals worldwide. Mesenchymal stem cells (MSCs) transplantation has been demonstrated to potentially ameliorate IDD progression, while the underlying mechanism has not been fully explained. Interleukin-1β (IL-1β) was used to induce nucleus pulposus cells (NPCs) injury. Bone marrow MSCs-derived exosomes were isolated using the super centrifugation method, and characterized using Transmission electron microscopy (TEM) and western blot. Cell viability was determined by MTT, while apoptosis was measured by Annexin-V staining using flow cytometry. miR-142-3fp and gene expressions were measured by real-time PCR. The protein expressions were determined by western blot. Herein, we found exosomes from bone marrow MSCs are circular vesicles, about 80 nm in diameter, and with robust expression of TSG101 and CD63, but without of Calnexin. MSCs exosomes alleviated NPCs apoptosis by reducing IL-1β-induced inflammatory cytokines secretion and MAPK signaling activation. Additionally, MSCs exosomes inhibited NPCs apoptosis and MAPK signaling by delivering miR-142-3p that targets mixed lineage kinase 3 (MLK3). Overexpression of MLK3 abolished the effects of MSCs exosomes on the inflammatory condition, cell apoptosis, and MAPK signaling activation in NPCs. The results confirmed that bone marrow MSCs-derived exosomes-packaged miR-142-3p alleviates NPCs injury through suppressing MAPK signaling by targeting MLK3. The work highlights the therapeutic effect of MSCs on IDD progression, and bone marrow MSCs exosomes might be apromising therapeutic strategy for IDD.

miR‑133b affects cell proliferation, invasion and chemosensitivity in renal cell carcinoma by inhibiting the ERK signaling pathway

Renal cell carcinoma has the highest incidence rate of cancer types in the urinary system. Moreover, microRNAs (miRNA) have been closely associated with numerous types of tumor. The present study aimed to investigate the effects of miRNA (miR)-133b on the proliferation, invasion and chemosensitivity of renal cell carcinoma cells, and to determine whether its mechanism was regulated by the ERK signaling pathway. Both renal cell carcinoma and adjacent healthy tissues from 60 patients, in addition to renal cell carcinoma lines, ACHN, Caki-1, A-498 and 786-O, and 293 cells, were used in this study. miR-133b expression was measured from renal cell carcinoma, adjacent healthy tissues and renal cell carcinoma cell lines by reverse transcription-quantitative PCR. Cells were transfected with miR-133b mimic to achieve miR-133b overexpression. The proliferative, migratory and invasive ability of the cells were evaluated using MTT, wound healing and Matrigel assays, respectively, and flow cytometry was used to detect the apoptotic rate. Following treatment with an ERK inhibitor, U0126, and activator, LM22B-10, western blotting was used to detect the expression of related proteins and the activity of the ERK signaling pathway. The overexpression of miR-133b significantly inhibited cell proliferation, migration and invasion, whilst inducing apoptosis and increasing the drug sensitivity of renal cell carcinoma cells to cisplatin, docetaxel and doxorubicin. The miR-133b mimic also increased the protein expression levels of Bax and decreased the expression levels of matrix metalloproteinase (MMP)-2, MMP-9, ATP-binding cassette subfamily G2, P-glycoprotein, Bcl-2 and proliferating cell nuclear antigen, as well as the phosphorylation of ERK (P<0.05). The administration of the U0216 inhibitor demonstrated similar effects to miR-133b overexpression, and there was no significant difference compared with the miR-133b mimic transfection (P>0.05). However, the overexpression of miR-133b combined with LM22B-10 treatment weakened the anticancer effects of miR-133b mimic transfection (P<0.05). In conclusion, miR-133b overexpression was observed to inhibit the proliferation, migration and invasion of renal cell carcinoma cells and improve chemotherapeutic sensitivity; it was suggested that the mechanism maybe related to the inhibition of ERK1/2 phosphorylation and thus decreased ERK signaling pathway activity.

The failure of DAC to induce OCT2 expression and its remission by hemoglobin-based nanocarriers under hypoxia in renal cell carcinoma

Background: Human organic cation transporter 2 (OCT2) is the most abundant and important uptake transporter involved in the renal excretion of cationic drugs. Abnormal hypermethylation- mediated silencing of OCT2 results in oxaliplatin resistance in renal cell carcinoma (RCC). The epigenetic activation of OCT2 by decitabine (DAC) reversed this resistance in normoxic conditions. Given the hypoxic characteristic of RCC, it is still unclear whether hypoxia promotes DAC resistance and is involved in the regulation of OCT2. Methods: The mRNA and protein expression of OCT2 was determined by qRT-PCR and Western blotting. MSRE-qPCR and BSP were used to examine methylation modifications at the OCT2 promoter. The ChIP-qPCR analysis was performed to detect the abundance of histone modification and HIF-1α. The accumulation of DAC and 5-mC were detected using LC-MS, and the amount of 5-hmC was determined by dot blot analysis. To understand the role of hypoxia in the regulation of equilibrative nucleoside transporter 1 (ENT1) expression, the HIF-1α KO cell model was constructed. The re-emulsion method was used for the construction of H-NPs, an oxygen nanocarrier based on hemoglobin, to alleviate the drug resistance of DAC under hypoxia. Results: DAC was unable to upregulate OCT2 expression in hypoxic conditions because of the hypermethylation and low H3K4me3 modification in its promoter region. Hypoxia-mediated repression of human ENT1, which was markedly suppressed in RCC, resulted in a decrease in the cellular accumulation of DAC. Besides, hypoxia-induced upregulation of histone deacetylase HDAC9, which impaired the enrichment of H3K27ac modification in the OCT2 promoter, led to the transcriptional repression of OCT2. H-NPs could attenuate the hypoxia-induced loss of DAC activity and sensitize RCC cells to the sequential combination therapy of DAC and oxaliplatin. Conclusions: Hypoxia-mediated repression of ENT1 led to the inability of DAC to upregulate the expression of OCT2 under hypoxia. H-NPs could alleviate resistance to oxaliplatin and DAC in RCC cells under hypoxia and may have potential clinical applications.

Identification of a new aggressive axis driven by ciliogenesis and absence of VDAC1-ΔC in clear cell Renal Cell Carcinoma patients

Rationale: Renal cell carcinoma (RCC) accounts for about 2% of all adult cancers, and clear cell RCC (ccRCC) is the most common RCC histologic subtype. A hallmark of ccRCC is the loss of the primary cilium, a cellular antenna that senses a wide variety of signals. Loss of this key organelle in ccRCC is associated with the loss of the von Hippel-Lindau protein (VHL). However, not all mechanisms of ciliopathy have been clearly elucidated.

Methods: By using RCC4 renal cancer cells and patient samples, we examined the regulation of ciliogenesis via the presence or absence of the hypoxic form of the voltage-dependent anion channel (VDAC1-ΔC) and its impact on tumor aggressiveness. Three independent cohorts were analyzed. Cohort A was from PREDIR and included 12 patients with hereditary pVHL mutations and 22 sporadic patients presenting tumors with wild-type pVHL or mutated pVHL; Cohort B included tissue samples from 43 patients with non-metastatic ccRCC who had undergone surgery; and Cohort C was composed of 375 non-metastatic ccRCC tumor samples from The Cancer Genome Atlas (TCGA) and was used for validation. The presence of VDAC1-ΔC and legumain was determined by immunoblot. Transcriptional regulation of IFT20/GLI1 expression was evaluated by qPCR. Ciliogenesis was detected using both mouse anti-acetylated α-tubulin and rabbit polyclonal ARL13B antibodies for immunofluorescence.

Results: Our study defines, for the first time, a group of ccRCC patients in which the hypoxia-cleaved form of VDAC1 (VDAC1-ΔC) induces resorption of the primary cilium in a Hypoxia-Inducible Factor-1 (HIF-1)-dependent manner. An additional novel group, in which the primary cilium is re-expressed or maintained, lacked VDAC1-ΔC yet maintained glycolysis, a signature of epithelial-mesenchymal transition (EMT) and more aggressive tumor progression, but was independent to VHL. Moreover, these patients were less sensitive to sunitinib, the first-line treatment for ccRCC, but were potentially suitable for immunotherapy, as indicated by the immunophenoscore and the presence of PDL1 expression.

Conclusion: This study provides a new way to classify ccRCC patients and proposes potential therapeutic targets linked to metabolism and immunotherapy.