The novel SMYD3 inhibitor EM127 impairs DNA repair response to chemotherapy-induced DNA damage and reverses cancer chemoresistance.

SMYD3 has been found implicated in cancer progression. Its overexpression correlates with cancer growth and invasion, especially in gastrointestinal tumors. SMYD3 transactivates multiple oncogenic mechanisms, favoring cancer development. Moreover, it was recently shown that SMYD3 is required for DNA restoration by promoting homologous recombination (HR) repair. In cellulo and in vivo models were employed to investigate the role of SMYD3 in cancer chemoresistance. Analyses of SMYD3-KO cells, drug-resistant cancer cell lines, patients' residual gastric or rectal tumors that were resected after neoadjuvant therapy and mice models were performed. In addition, the novel SMYD3 covalent inhibitor EM127 was used to evaluate the impact of manipulating SMYD3 activity on the sensitization of cancer cell lines, tumorspheres and cancer murine models to chemotherapeutics (CHTs). Here we report that SMYD3 mediates cancer cell sensitivity to CHTs. Indeed, cancer cells lacking SMYD3 functions showed increased responsiveness to CHTs, while restoring its expression promoted chemoresistance. Specifically, SMYD3 is essential for the repair of CHT-induced double-strand breaks as it methylates the upstream sensor ATM and allows HR cascade propagation through CHK2 and p53 phosphorylation, thereby promoting cancer cell survival. SMYD3 inhibition with the novel compound EM127 showed a synergistic effect with CHTs in colorectal, gastric, and breast cancer cells, tumorspheres, and preclinical colorectal cancer models. Overall, our results show that targeting SMYD3 may be an effective therapeutic strategy to overcome chemoresistance.

Sanese P ，De Marco K ，Lepore Signorile M ，La Rocca F ，Forte G ，Latrofa M ，Fasano C ，Disciglio V ，Di Nicola E ，Pantaleo A ，Bianco G ，Spilotro V ，Ferroni C ，Tubertini M ，Labarile N ，De Marinis L ，Armentano R ，Gigante G ，Lantone V ，Lantone G ，Naldi M ，Bartolini M ，Varchi G ，Del Rio A ，Grossi V ，Simone C ... -  《JOURNAL OF EXPERIMENTAL & CLINICAL CANCER RESEARCH》

SMYD3 Modulates AMPK-mTOR Signaling Balance in Cancer Cell Response to DNA Damage.

Lepore Signorile M ，Sanese P ，Di Nicola E ，Fasano C ，Forte G ，De Marco K ，Disciglio V ，Latrofa M ，Pantaleo A ，Varchi G ，Del Rio A ，Grossi V ，Simone C ... -  《Cells》

Discovery of the 4-aminopiperidine-based compound EM127 for the site-specific covalent inhibition of SMYD3.

Recent findings support the hypothesis that inhibition of SMYD3 methyltransferase may be a therapeutic avenue for some of the deadliest cancer types. Herein, active site-selective covalent SMYD3 inhibitors were designed by introducing an appropriate reactive cysteine trap into reversible first-generation SMYD3 inhibitors. The 4-aminopiperidine derivative EM127 (11C) bearing a 2-chloroethanoyl group as reactive warhead showed selectivity for Cys186, located in the substrate/histone binding pocket. Selectivity towards Cys186 was retained even at high inhibitor/enzyme ratio, as shown by mass spectrometry. The mode of interaction with the SMYD3 substrate/histone binding pocket was revealed by crystallographic studies. In enzymatic assays, 11C showed a stronger SMYD3 inhibitory effect compared to the reference inhibitor EPZ031686. Remarkably, 11C attenuated the proliferation of MDA-MB-231 breast cancer cell line at the same low micromolar range of concentrations that reduced SMYD3 mediated ERK signaling in HCT116 colorectal cancer and MDA-MB-231 breast cancer cells. Furthermore, 11C (5 μM) strongly decreased the steady-state mRNA levels of genes important for tumor biology such as cyclin dependent kinase 2, c-MET, N-cadherin and fibronectin 1, all known to be regulated, at least in part, by SMYD3. Thus, 11C is as a first example of second generation SMYD3 inhibitors; this agent represents a covalent and a site specific SMYD3 binder capable of potent and prolonged attenuation of methyltransferase activity.

Parenti MD ，Naldi M ，Manoni E ，Fabini E ，Cederfelt D ，Talibov VO ，Gressani V ，Guven U ，Grossi V ，Fasano C ，Sanese P ，De Marco K ，Shtil AA ，Kurkin AV ，Altieri A ，Danielson UH ，Caretti G ，Simone C ，Varchi G ，Bartolini M ，Del Rio A ... -  《-》

SMYD3 Impedes Small Cell Lung Cancer Sensitivity to Alkylation Damage through RNF113A Methylation-Phosphorylation Cross-talk.

Small cell lung cancer (SCLC) is the most fatal form of lung cancer, with dismal survival, limited therapeutic options, and rapid development of chemoresistance. We identified the lysine methyltransferase SMYD3 as a major regulator of SCLC sensitivity to alkylation-based chemotherapy. RNF113A methylation by SMYD3 impairs its interaction with the phosphatase PP4, controlling its phosphorylation levels. This cross-talk between posttranslational modifications acts as a key switch in promoting and maintaining RNF113A E3 ligase activity, essential for its role in alkylation damage response. In turn, SMYD3 inhibition restores SCLC vulnerability to alkylating chemotherapy. Our study sheds light on a novel role of SMYD3 in cancer, uncovering this enzyme as a mediator of alkylation damage sensitivity and providing a rationale for small-molecule SMYD3 inhibition to improve responses to established chemotherapy. SCLC rapidly becomes resistant to conventional chemotherapy, leaving patients with no alternative treatment options. Our data demonstrate that SMYD3 upregulation and RNF113A methylation in SCLC are key mechanisms that control the alkylation damage response. Notably, SMYD3 inhibition sensitizes cells to alkylating agents and promotes sustained SCLC response to chemotherapy. This article is highlighted in the In This Issue feature, p. 2007.

Lukinović V ，Hausmann S ，Roth GS ，Oyeniran C ，Ahmad T ，Tsao N ，Brickner JR ，Casanova AG ，Chuffart F ，Benitez AM ，Vayr J ，Rodell R ，Tardif M ，Jansen PWTC ，Couté Y ，Vermeulen M ，Hainaut P ，Mazur PK ，Mosammaparast N ，Reynoird N ... -  《-》

MMSET/WHSC1 enhances DNA damage repair leading to an increase in resistance to chemotherapeutic agents.

Shah MY ，Martinez-Garcia E ，Phillip JM ，Chambliss AB ，Popovic R ，Ezponda T ，Small EC ，Will C ，Phillip MP ，Neri P ，Bahlis NJ ，Wirtz D ，Licht JD ... -  《-》