Effect of SMYD3 on biological behavior and H3K4 methylation in bladder cancer

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.

Clinicopathological and Prognostic Significance of SMYD3 in Human Cancers: A Systematic Review and Meta-analysis

Background: Dysregulation of the SET and MYND domain-containing protein 3 (SMYD3) has been found in multiple cancers. This meta-analysis aimed to elucidate the association between SMYD3 expression and clinical outcomes in cancer. Methods: A systematic search of Web of Science, Embase, PubMed, Cochrane Library, and CNKI was conducted. The relationship between SMYD3 expression and cancer patients' overall survival (OS) was evaluated using pooled hazard ratios (HRs) and their corresponding confidence intervals (95% CIs). The association between SMYD3 expression and clinicopathological features was assessed using odds ratios (ORs) with 95% CIs, including tumor size, lymph node metastasis (LNM), distance metastasis, and TNM stage. Results: In total, 715 cancer patients with hepatocellular carcinoma, nonsmall cell lung carcinoma, esophageal squamous cell carcinoma, glioma, colorectal cancer, and/or bladder cancer from seven studies were included in our meta-analysis. SMYD3 overexpression was significantly associated with poor OS (HR = 1.81, 95% CI: 1.38-2.37, p < 0.01) with no heterogeneity (I² = 0.0%, p = 0.929) in various cancers. Subgroup analysis showed that the prognostic value of SMYD3 across multiple tumors was constant as the tumor type, sample size, and methods of data extraction changed. Increased SMYD3 expression was positively associated with LNM (OR = 1.88, 95% CI = 1.33-2.66, p < 0.001), tumor size (OR = 1.68, 95% CI: 1.09-2.60, p = 0.019), and advanced TNM stage (OR = 1.84, 95% CI: 1.25-2.69, p = 0.002). Conclusions: Upregulation of SMYD3 was significantly associated with poor prognosis in various cancers, suggesting that SMYD3 may be a useful prognostic biomarker.

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.

SMYD3 confers cisplatin chemoresistance of NSCLC cells in an ANKHD1-dependent manner

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Up-regulated SMYD3 correlates with worse prognosis and controls DDP resistance of NSCLC.

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ANKHD1 interacts with and is essential for SMYD3-induced DDP resistance.

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CDK2 is identified to be a downstream effector of SMYD3-ANKHD1 in NSCLC.

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SMYD3-ANKHD1 critically regulates the growth DDP-resistant NSCLC cells in vivo.

Background

Cisplatin (DDP) remains the backbone of chemotherapy for non-small cell lung cancer (NSCLC), yet its clinical efficacy is limited by DDP resistance. We aim to investigate the role of the SET and MYND domain-containing protein 3 (SMYD3) in DDP resistance of NSCLC.

Methods

Expression pattern of SMYD3 was determined in NSCLC tissues using qRT-PCR, which also validated its correlation with NSCLC clinicopathological stages. Impacts of SMYD3 on DDP resistance were evaluated by knocking down SMYD3 in DDP-resistant cells and overexpressing it in DDP-sensitive cells, and assessed for several phenotypes: IC₅₀ by MTT, long-term proliferation by colony formation, apoptosis and cell-cycle distribution by flow cytometry. The interaction between Ankyrin Repeat and KH Domain Containing 1 (ANKHD1) and SMYD3 was examined by co-immunoprecipitation and immunofluorescence. The transcriptional regulation of SMYD3 on cyclin-dependent kinase 2 (CDK2) promoter regions was confirmed using chromatin-immunoprecipitation. The in vivo experiments using DDP-resistant cells with altered SMYD3 and ANKHD1 expression were further performed to verify the SMYD3/ANKHD1 axis.

Results

Highly expressed SMYD3 was observed in NSCLC tissues or cells, acted as a sensitive indicator for NSCLC, correlated with higher TNM stages or resistant to DDP treatment, and shorter overall survival. The promotion of SMYD3 on DDP resistance requires co-regulator, ANKHD1. CDK2 was identified as a downstream effector. In vivo, SMYD3 knockdown inhibited the growth of DDP-resistant NSCLC cells, which was abolished by ANKHD1 overexpression.

Conclusions

SMYD3 confers NSCLC cells chemoresistance to DDP in an ANKHD1-dependent manner, providing novel therapeutic targets to overcome DDP resistance in NSCLC .

EZH2 and SMYD3 expression in papillary thyroid cancer

Recent studies have revealed the significant role of SMYD3 and EZH2 genes in the development and aggressiveness of numerous types of malignant tumor. Therefore, the present study aimed to investigate the expression of SMYD3 and EZH2 in papillary thyroid cancer, and to determine the correlation between the expression of these genes and clinical characteristics. Resected thyroid tissue samples from 62 patients with papillary thyroid cancer were investigated. Thyroid tissue derived from the healthy regions of removed nodular goiters from 30 patients served as the control group. Reverse transcription-quantitative PCR analysis was employed to detect relative mRNA expression levels. Primer sequences and TaqMan^® hydrolysis probe positions for EZH2 and SMYD3 were determined using the Roche Universal ProbeLibrary Assay Design Center version 2.50. EZH2 expression was detected in all thyroid cancer samples and in 83.3% of benign lesions. Notably, EZH2 was revealed to be upregulated in thyroid cancer tissues compared with control tissues (P=0.0002). EZH2 expression was positively correlated with tumor stage (P<0.0001; r=0.504), and multiple comparison analysis revealed that the highest expression of EZH2 was detected in samples staged pT4 (P=0.0001). SMYD3 expression was detected in all thyroid cancer samples and in 96.7% of healthy thyroid tissues; notably, the expression levels were similar in both groups. In addition, there was no correlation between SMYD3 expression and the aggressiveness of papillary thyroid cancer. In conclusion, overexpression of the EZH2 gene may be associated with the development of papillary thyroid cancer and EZH2 may be a potential therapeutic target in papillary thyroid cancer.

SMYD3: a regulator of epigenetic and signaling pathways in cancer

Chromatin modifiers and their implications in oncogenesis have been an exciting area of cancer research. These are enzymes that modify chromatin via post-translational modifications such as methylation, acetylation, sumoylation, phosphorylation, in addition to others. Depending on the modification, chromatin modifiers can either promote or repress transcription. SET and MYN-domain containing 3 (SMYD3) is a chromatin modifier that has been implicated in the development and progression of various cancer types. It was first reported to tri-methylate Histone 3 Lysine 4 (H3K4), a methylation mark known to promote transcription. However, since this discovery, other histone (H4K5 and H4K20, for example) and non-histone (VEGFR, HER2, MAP3K2, ER, and others) substrates of SMYD3 have been described, primarily in the context of cancer. This review aims to provide a background on basic characteristics of SMYD3, such as its protein structure and tissue expression profiles, discuss reported histone and non-histone substrates of SMYD3, and underscore prognostic and functional implications of SMYD3 in cancer. Finally, we briefly discuss ongoing efforts to develop inhibitors of SMYD3 for future therapeutic use. It is our hope that this review will help synthesize existing research on SMYD3 in an effort to propel future discovery.