N-phenyl ureidobenzenesulfonates (PUB-SOs) is a new class of promising anticancer agents inducing replication stresses and cell cycle arrest in S-phase. However, the pharmacological target of PUB-SOs was still unidentified. Consequently, the objective of the present study was to identify and confirm the pharmacological target of the prototypical PUB-SO named 2-ethylphenyl 4-(3-ethylureido)benzenesulfonate (SFOM-0046) leading to the cell cycle arrest in S-phase. The antiproliferative and the cytotoxic activities of SFOM-0046 were characterized using the NCI-60 screening program and its fingerprint was analyzed by COMPARE algorithm. Then, human dihydroorotate dehydrogenase (hDHODH) colorimetric assay, uridine rescuing cell proliferation and molecular docking in the brequinar-binding site were performed. As a result, SFOM-0046 exhibited a mean antiproliferative activity of 3.5 μM in the NCI-60 screening program and evidenced that leukemia and colon cancer cell panels were more sensitive to SFOM-0046. COMPARE algorithm showed that the SFOM-0046 cytotoxic profile is equivalent to the ones of brequinar and dichloroallyl lawsone, two inhibitors of hDHODH. SFOM-0046 inhibited the hDHODH in the low nanomolar range (IC₅₀ = 72 nM) and uridine rescued the cell proliferation of HT-29, HT-1080, M21 and MCF-7 cancer cell lines in the presence of SFOM-0046. Finally, molecular docking showed a binding pose of SFOM-0046 interacting with Met43 and Phe62 present in the brequinar-binding site. In conclusion, PUB-SOs and notably SFOM-0046 are new small molecules hDHODH inhibitors triggering replication stresses and S-phase arrest.

ñ-苯基脲基苯磺酸盐（PUB-SOs）是一类新的有前途的抗癌剂，可诱导S期复制应激和细胞周期停滞。但是，PUB-SOs的药理学目标仍然不确定。因此，本研究的目的是鉴定和确认原型PUB-SO的药理学目标，该物质称为2-乙基苯基4-（3-乙基脲基）苯磺酸盐（SFOM-0046），导致S期细胞周期停滞。使用NCI-60筛选程序表征SFOM-0046的抗增殖和细胞毒性活性，并通过COMPARE算法分析其指纹。然后，进行了人二氢乳清酸脱氢酶（hDHODH）比色测定，尿苷拯救细胞增殖和分子固定在布雷奎纳结合位点。结果是，SFOM-0046在NCI-60筛选程序中显示出3.5μM的平均抗增殖活性，并证明白血病和结肠癌细胞组对SFOM-0046更敏感。COMPARE算法显示，SFOM-0046的细胞毒性谱与两种hDHODH抑制剂布雷基纳和二氯烯丙基拉索酮相同。SFOM-0046在低纳摩尔范围内抑制了hDHODH（IC₅₀  = 72 nM）和尿苷在SFOM-0046存在的情况下挽救了HT-29，HT-1080，M21和MCF-7癌细胞的细胞增殖。最后，分子对接显示出SFOM-0046与brequinar结合位点中存在的Met43和Phe62相互作用的结合姿势。总之，PUB-SOs，特别是SFOM-0046是新的小分子hDHODH抑制剂，可触发复制压力和S期阻滞。