Sulforaphane (SFN) is one of most important dietary constituents of broccoli (Brassica oleracea) and other cruciferous vegetables, which have been reported to exhibit health benefits, including prevention and therapy of cancer, such as colorectal carcinoma (CRC). The objective of this study was to determine whether the anticancer effect of SFN on colon cancer HT-29 cell line could be improved by the combined treatment with molecules inhibiting microRNAs (miRNAs) involved in CRC. As miRNA inhibiting molecules we focused on peptide-nucleic acids (PNAs). As miRNA to be targeted, miR-15b-5p was selected on the basis of several information present in the literature and confirming that miR-15b-5p is overexpressed in colon cancer patients, and that its targeting decreases cell migration and metastasis in colorectal cancer. In this article, we described for the first time the efficacy of targeting miR-15b-5p by using a PNA against miR-15b-5p (R8-PNA-a15b), functionalized with an octoarginine peptide (R8) for maximizing cellular uptake. The miR-15b-5p downregulation in the colon cancer HT-29 cell line was associated with inhibition of in vitro cell growth and activation of the proapoptotic pathway, demonstrated by a sharp increase of late apoptotic cells in HT-29-treated cell populations. A second conclusion of this study is that the R8-PNA-a15b might be proposed in “combo-therapy” associated with SFN. To our knowledge, no report is available in the literature on a combination between SFN and miRNA-targeting molecules. Our data demonstrate that this combined treatment leads to a very high proportion of apoptotic HT-29 cells (over 85%), a value higher than the sum of the values of apoptotic cells obtained after singularly administered regents (either SFN or R8-PNA-a15b).

中文翻译：

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通过共同施用萝卜硫素和靶向 miR-15b-5p 的肽核酸在人结肠癌 HT-29 细胞系中诱导高水平的细胞凋亡。

萝卜硫素 (SFN) 是西兰花 ( Brassica oleracea) 和其他十字花科蔬菜，据报道这些蔬菜具有健康益处，包括预防和治疗癌症，例如结直肠癌 (CRC)。本研究的目的是确定 SFN 对结肠癌 HT-29 细胞系的抗癌作用是否可以通过与抑制 CRC 相关的微小 RNA (miRNA) 的分子联合治疗来提高。作为 miRNA 抑制分子，我们专注于肽-核酸 (PNA)。作为要靶向的 miRNA，根据文献中的一些信息选择了 miR-15b-5p，并确认 miR-15b-5p 在结肠癌患者中过表达，并且其靶向作用降低了结直肠癌中的细胞迁移和转移. 在这篇文章中，我们首次描述了通过使用针对 miR-15b-5p 的 PNA (R8-PNA-a15b) 靶向 miR-15b-5p 的功效，该 PNA 用八精氨酸肽 (R8) 功能化以最大化细胞摄取。结肠癌 HT-29 细胞系中 miR-15b-5p 的下调与抑制体外细胞生长和促凋亡途径的激活，通过 HT-29 处理的细胞群中晚期凋亡细胞的急剧增加来证明。本研究的第二个结论是，R8-PNA-a15b 可能被提出用于与 SFN 相关的“联合疗法”。据我们所知，文献中没有关于 SFN 和 miRNA 靶向分子组合的报告。我们的数据表明，这种联合治疗导致了非常高比例的 HT-29 细胞凋亡（超过 85%），该值高于单独给药后获得的凋亡细胞值的总和（SFN 或 R8-PNA- a15b)。