硫化氢 (H2S) 最近因其在加剧乳腺癌 (BC) 致瘤性方面的关键作用而受到密切关注。几种癌症异常表达 H2S 合成酶；胱硫醚-β-合酶 (CBS) 和胱硫醚-γ-裂解酶 (CSE)。然而，它们在 BC 中的水平和相互依赖性需要进一步研究。首先，本研究旨在证明 BC 中 H2S 合成酶与正常组织中的比较表达谱。此外，研究 CBS 和 CSE 之间的相互关系并强调双重目标的重要性。最后，寻找一种有效的H2S合成酶双重阻遏物，可以阻止H2S产生并降低TNBC致病性。对40名BC患者的肿瘤与正常组织进行了配对分析。用寡核苷酸转染 TNBC 细胞系 MDA-MB-231，以研究 H2S 介导的分子机制。进行计算机筛选以确定 CBS 和 CSE 的双重调节器。使用 qRT-PCR 进行基因表达分析，并使用蛋白质印迹在蛋白质水平上进行确认。使用 MTT、迁移和克隆形成分析评估 TNBC 标志。使用 AzMc 荧光探针检测 H2S 水平。BC 组织表现出 CBS 和 CSE 水平升高。有趣的是，在 CBS 敲低后，CSE 水平增加，补偿了 TNBC 细胞中 H2S 的产生，强调了在 TNBC 中双重靶向这两种酶的重要性。计算机筛选表明 miR-939-5p 作为 CBS 和 CSE 的调节剂，具有高结合分数。在 BC 组织中发现 miR-939-5p 表达水平较低，尤其是侵袭性亚型。 miR-939-5p 的异位表达显着抑制 CBS 和 CSE 转录物和蛋白质水平，减少 H2S 产生并减弱 TNBC 标志。此外，它通过上调 NKG2D 配体、MICB 和 ULBP2 以及减少免疫抑制细胞因子 IL-10 来提高 TNBC 细胞的免疫监视效力。这项研究揭示了 CBS 和 CSE 之间的相互关系以及它们双重作用的重要性。目标定位，特别是在 TNBC 中。它还假设 miR-939-5p 作为 CBS 和 CSE 的有效双重阻遏物，克服它们在 H2S 产生中的冗余，这种机制可以潜在地减弱 TNBC 致癌性并改善免疫原性反应。© 2023 作者。

Hydrogen sulfide (H2S) has been recently scrutinized for its critical role in aggravating breast cancer (BC) tumorigenicity. Several cancers aberrantly express H2S synthesizing enzymes; Cystathionine-β-synthase (CBS) and cystathionine-γ-lyase (CSE). However, their levels and interdependence in BC require further studies.Firstly, this study aimed to demonstrate a comparative expression profile of H2S synthesizing enzymes in BC vs normal tissue. Moreover, to investigate the reciprocal relationship between CBS and CSE and highlight the importance of dual targeting. Finally, to search for a valid dual repressor of the H2S synthesizing enzymes that could cease H2S production and reduce TNBC pathogenicity.Pairwise analysis of tumor vs. normal tissues of 40 BC patients was carried out. The TNBC cell line MDA-MB-231 was transfected with oligonucleotides to study the H2S mediated molecular mechanisms. In silico screening was performed to identify dual regulator(s) for CBS and CSE. Gene expression analysis was performed using qRT-PCR and was confirmed on protein level using Western blot. TNBC hallmarks were evaluated using MTT, migration, and clonogenicity assays. H2S levels were detected using a AzMc fluorescent probe.BC tissues exhibited elevated levels of both CBS and CSE. Interestingly, upon CBS knockdown, CSE levels increased compensating for H2S production in TNBC cells, underlining the importance of dually targeting both enzymes in TNBC. In silico screening suggested miR-939-5p as a regulator of both CBS and CSE with high binding scores. Low expression levels of miR-939-5p were found in BC tissues, especially the aggressive subtypes. Ectopic expression of miR-939-5p significantly repressed CBS and CSE transcript and protein levels, diminished H2S production and attenuated TNBC hallmarks. Moreover, it improved the immune surveillance potency of TNBC cells through up regulating the NKG2D ligands, MICB and ULBP2 and reducing the immune suppressive cytokine IL-10.This study sheds light on the reciprocal relationship between CBS and CSE and on the importance of their dual targeting, particularly in TNBC. It also postulates miR-939-5p as a potent dual repressor for CBS and CSE overcoming their redundancy in H2S production, a mechanism that can potentially attenuate TNBC oncogenicity and improves the immunogenic response.© 2023 The Authors.