SMYD2 aggravates gastrointestinal stromal tumor via upregulation of EZH2 and downregulation of TET1

Role of SMYD2 in gastrointestinal cancer progression (Review)

Gastrointestinal cancer is one of the most prevalent malignancies in humans and is often associated with a poor prognosis. Understanding the molecular mechanisms underlying cancer progression and severity is essential for the development of effective cancer therapies. Abnormal protein methylation is associated with the occurrence and advancement of cancer, highlighting the importance of protein methyltransferase research. SET and MYND domain-containing protein 2 (SMYD2), a lysine methyltransferase, has emerged as a promising small molecule target for cancer treatment. Notably, SMYD2 is implicated in the pathogenesis of several diseases, including gastrointestinal cancer. SMYD2 is closely associated with the tumorigenesis, proliferation, migration and other biological processes of gastrointestinal cancer, indicating its potential as a novel therapeutic target. The present review offers an in-depth analysis of SMYD2, covering its structural characteristics, regulatory pathways and functional significance. By assessing the biological roles and therapeutic potential of SMYD2, the current review presents fresh insights and perspectives for advancing research in different types of gastrointestinal cancer.

The Olive Oil Phenolic S-(-)-Oleocanthal Suppresses Colorectal Cancer Progression and Recurrence by Modulating SMYD2-EZH2 and c-MET Activation

Background/Objectives: Colorectal cancer (CRC) is the third most common cancer in the US and the second leading cancer-associated mortality cause. Available CRC therapies achieve modest outcomes and fail to prevent its recurrence. Epidemiological studies indicated that the Mediterranean diet rich in olive oil reduced CRC incidence. This study aimed at the identification and assessment of active anti-CRC olive phenolics. Methods: The MTT, wound-healing and colony formation assays were used to discover and assess the in vitro anti-CRC activity of olive phenolics. A nude mouse xenografting model was used to assess the in vivo CRC progression and recurrence suppressive activity of OC in pure and crude forms. OC was isolated from olive oil using liquid-liquid extractions. Results: Screening of olive phenolics for in vitro antiproliferative activity against a diverse panel of CRC cell lines identified the extra-virgin olive oil (EVOO) S-(-)-oleocanthal (OC) as the most active hit. OC showed IC50 values of 4.2, 9.8, 14.5, and 4.9 μM against HCT-116, COLO-320DM, WiDr, and SW48 CRC cells, respectively. The lysine methyltransferases SMYD2 and EZH2, along with the receptor tyrosine kinase c-MET proved aberrantly dysregulated in invasive and metastatic CRC. SMYD2 and c-MET were validated as OC molecular targets in multiple malignancies. Daily oral 10 mg/kg OC treatments over 15 days suppressed 72.5% of the KRAS mutant HCT-116-Luc cells tumors weight in male nude mice. Continued OC daily oral use after primary tumor surgical excision over an additional 40 days significantly suppressed the HCT-116-Luc locoregional tumor recurrence and totally prevented the distant tumor recurrence. The SMYD2-EZH2 expressions and c-MET activation were notably suppressed by OC treatments in vitro and in collected animal primary tumors. Conclusions: OC and olive phenolics are potential nutraceutical interventions useful for CRC control and the prevention of its relapse.

Lysine methyltransferase SMYD2 enhances androgen receptor signaling to modulate CRPC cell resistance to enzalutamide

Androgen receptors (ARs) play key roles in prostate cancer (PCa) progression and castration-resistant prostate cancer (CRPC) resistance to drug therapy. SET and MYND domain containing protein 2 (SMYD2), a lysine methyltransferase, has been reported to promote tumors by transcriptionally methylating important oncogenes or tumor repressor genes. However, the role of SMYD2 in CRPC drug resistance remains unclear. In this study, we found that SMYD2 expression was significantly upregulated in PCa tissues and cell lines. High SMYD2 expression indicated poor CRPC-free survival and overall survival in patients. SMYD2 knockdown dramatically inhibited the proliferation, migration, invasion, and epithelial-mesenchymal transition (EMT) potential of 22Rv1 and C4-2 cells. Conversely, ectopic overexpression of SMYD2 promoted these effects in 22Rv1 and C4-2 cells. Mechanistically, SMYD2 methylated and phosphorylated ARs to affect AR ubiquitination and proteasome degradation, which further alters the AR transcriptome in CRPC cells. Importantly, the SMYD2 inhibitor AZ505 had a synergistic therapeutic effect with enzalutamide in CRPC cells and mouse models; however, it could also re-sensitize resistant CRPC cells to enzalutamide. Our findings demonstrated that SMYD2 enhances the methylation and phosphorylation of ARs and affects AR ubiquitination and proteasome degradation to modulate CRPC cell resistance to enzalutamide, indicating that SMYD2 serves as a crucial oncogene in PCa and is an ideal therapeutic target for CRPC.

Targeting BCL6 in Gastrointestinal Stromal Tumor Promotes p53-Mediated Apoptosis to Enhance the Antitumor Activity of Imatinib

Imatinib mesylate (IM) has revolutionized the treatment of gastrointestinal stromal tumor (GIST). However, most patients inevitably acquire IM resistance. Second- and third-line treatments exhibit modest clinical benefits with a median time to disease progression of 4 to 6 months, highlighting the urgency for novel therapeutic approaches. Here, we report that the expression of BCL6, a known oncogenic driver and transcriptional repressor, was significantly induced in GIST cells following IM treatment. Elevated BCL6 levels suppressed apoptosis and contributed to IM resistance. Mechanistically, BCL6 recruited SIRT1 to the TP53 promoter to modulate histone acetylation and transcriptionally repress TP53 expression. The reduction in p53 subsequently attenuated cell apoptosis and promoted tolerance of GIST cells to IM. Concordantly, treatment of GIST cells showing high BCL6 expression with a BCL6 inhibitor, BI-3802, conferred IM sensitivity. Furthermore, BI-3802 showed striking synergy with IM in IM-responsive and IM-resistant GIST cells in vitro and in vivo. Thus, these findings reveal a role for BCL6 in IM resistance and suggest that a combination of BCL6 inhibitors and IM could be a potentially effective treatment for GIST.

SIGNIFICANCE

BCL6 drives resistance to imatinib by inhibiting p53-mediated apoptosis and can be targeted in combination with imatinib to synergistically suppress tumor growth, providing a therapeutic strategy for treating gastrointestinal stromal tumor.

Epigenetic regulation of SMAD3 by histone methyltransferase SMYD2 promotes lung cancer metastasis

Epigenetic alterations, especially histone methylation, are key factors in cell migration and invasion in cancer metastasis. However, in lung cancer metastasis, the mechanism by which histone methylation regulates metastasis has not been fully elucidated. Here, we found that the histone methyltransferase SMYD2 is overexpressed in lung cancer and that knockdown of SMYD2 could reduce the rates of cell migration and invasion in lung cancer cell lines via direct downregulation of SMAD3 via SMYD2-mediated epigenetic regulation. Furthermore, using an in vitro epithelial-mesenchymal transition (EMT) system with a Transwell system, we generated highly invasive H1299 (In-H1299) cell lines and observed the suppression of metastatic features by SMYD2 knockdown. Finally, two types of in vivo studies revealed that the formation of metastatic tumors by shSMYD2 was significantly suppressed. Thus, we suggest that SMYD2 is a potential metastasis regulator and that the development of SMYD2-specific inhibitors may help to increase the efficacy of lung cancer treatment.