Colorectal cancer is a highly malignant cancer that is inherently resistant to many chemotherapeutic drugs owing to the complicated tumor-supportive microenvironment (TME). Tumor-associated macrophages (TAM) are known to mediate colorectal cancer metastasis and relapse and are therefore a promising therapeutic target. In the current study, we first confirmed the anti-inflammatory effect of 7S,15R-dihydroxy-16S,17S-epoxy-docosapentaenoic acid (diHEP-DPA), a novel DHA dihydroxy derivative synthesized in our previous work. We found that diHEP-DPA significantly reduced lipopolysaccharide (LPS)-induced inflammatory cytokines secretion of THP1 macrophages, IL-6, and TNF-α. As expected, diHEP-DPA also modulated TAM polarization, as evidenced by decreased gene and protein expression of the TAM markers, CD206, CD163, VEGF, and TGF-β1. During the polarization process, diHEP-DPA treatment decreased the concentration of TGF-β1, IL-1β, IL-6, and TNF-α in culture supernatants via inhibiting the NF-κB pathway. Moreover, diHEP-DPA blocked immunosuppression by reducing the expression of SIRPα in TAMs and CD47 in colorectal cancer cells. Knowing that an inflammatory TME largely serves to support epithelial-mesenchymal transition (EMT) and cancer stemness, we tested whether diHEP-DPA acted through polarization of TAMs to regulate these processes. The intraperitoneally injected diHEP-DPA inhibited tumor growth when administered alone or in combination with 5-fluorouracil (5-FU) chemotherapy in vivo. We further found that diHEP-DPA effectively reversed TAM-conditioned medium (TCCM)-induced EMT and enhanced colorectal cancer stemness, as evidenced by its inhibition of colorectal cancer cell migration, invasion and expression of EMT markers, as well as cancer cell tumorspheres formation, without damaging colorectal cancer cells. DiHEP-DPA reduced the population of aldehyde dehydrogenase (ALDH)-positive cells and expression of colorectal stemness marker proteins (CD133, CD44, and Sox2) by modulating TAM polarization. Additionally, diHEP-DPA directly inhibited cancer stemness by inducing the production of reactive oxygen species (ROS), which, in turn, reduced the phosphorylation of nuclear signal transducer and activator of transcription 3 (STAT3). These data collectively suggest that diHEP-DPA has the potential for development as an anticancer agent against colorectal cancer.

中文翻译：

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7S,15R-Dihydroxy-16S,17S-Epoxy-Docosapentaenoic Acid，一种新型 DHA 环氧衍生物，通过肿瘤相关巨噬细胞功能的复极化和 ROS/STAT3 信号通路抑制结直肠癌干性

结直肠癌是一种高度恶性的癌症，由于复杂的肿瘤支持微环境（TME），对许多化疗药物具有固有的耐药性。已知肿瘤相关巨噬细胞 (TAM) 介导结直肠癌转移和复发，因此是一个有希望的治疗靶点。在目前的研究中，我们首先证实了 7S,15R-dihydroxy-16S,17S-epoxy-docosapentaenoic acid (diHEP-DPA) 的抗炎作用，这是我们之前工作中合成的一种新型 DHA 二羟基衍生物。我们发现 diHEP-DPA 显着降低了脂多糖 (LPS) 诱导的 THP1 巨噬细胞、IL-6 和 TNF-α 的炎性细胞因子分泌。正如预期的那样，diHEP-DPA 还调节了 TAM 极化，这可以通过 TAM 标志物 CD206、CD163、VEGF 和 TGF-β1 的基因和蛋白质表达降低来证明。在极化过程中，diHEP-DPA 处理通过抑制 NF-κB 通路降低培养上清液中 TGF-β1、IL-1β、IL-6 和 TNF-α 的浓度。此外，diHEP-DPA 通过降低结直肠癌细胞中 TAM 中 SIRPα 和 CD47 的表达来阻断免疫抑制。知道炎性 TME 主要用于支持上皮间质转化 (EMT) 和癌症干性，我们测试了 diHEP-DPA 是否通过 TAM 的极化来调节这些过程。当单独给药或与 5-氟尿嘧啶 (5-FU) 化疗联合给药时，腹腔注射 diHEP-DPA 可抑制肿瘤生长。我们进一步发现，diHEP-DPA 有效地逆转了 TAM 条件培养基 (TCCM) 诱导的 EMT 并增强了结直肠癌的干性，其抑制大肠癌细胞迁移、侵袭和 EMT 标志物的表达以及癌细胞肿瘤球的形成，而不损害大肠癌细胞，证明了这一点。DiHEP-DPA 通过调节 TAM 极化减少了醛脱氢酶 (ALDH) 阳性细胞的数量和结肠直肠干细胞标记蛋白（CD133、CD44 和 Sox2）的表达。此外，diHEP-DPA 通过诱导活性氧 (ROS) 的产生直接抑制癌症干细胞，这反过来又降低了核信号转导和转录激活因子 3 (STAT3) 的磷酸化。这些数据共同表明，diHEP-DPA 具有作为结直肠癌抗癌剂发展的潜力。不损害结肠直肠癌细胞。DiHEP-DPA 通过调节 TAM 极化减少了醛脱氢酶 (ALDH) 阳性细胞的数量和结肠直肠干细胞标记蛋白（CD133、CD44 和 Sox2）的表达。此外，diHEP-DPA 通过诱导活性氧 (ROS) 的产生直接抑制癌症干细胞，这反过来又降低了核信号转导和转录激活因子 3 (STAT3) 的磷酸化。这些数据共同表明，diHEP-DPA 具有作为结直肠癌抗癌剂发展的潜力。不损害结肠直肠癌细胞。DiHEP-DPA 通过调节 TAM 极化减少了醛脱氢酶 (ALDH) 阳性细胞的数量和结肠直肠干细胞标记蛋白（CD133、CD44 和 Sox2）的表达。此外，diHEP-DPA 通过诱导活性氧 (ROS) 的产生直接抑制癌症干细胞，这反过来又降低了核信号转导和转录激活因子 3 (STAT3) 的磷酸化。这些数据共同表明，diHEP-DPA 具有作为结直肠癌抗癌剂发展的潜力。diHEP-DPA 通过诱导活性氧 (ROS) 的产生直接抑制癌症干细胞，这反过来又降低了核信号转导和转录激活因子 3 (STAT3) 的磷酸化。这些数据共同表明，diHEP-DPA 具有作为结直肠癌抗癌剂发展的潜力。diHEP-DPA 通过诱导活性氧 (ROS) 的产生直接抑制癌症干细胞，这反过来又降低了核信号转导和转录激活因子 3 (STAT3) 的磷酸化。这些数据共同表明，diHEP-DPA 具有作为结直肠癌抗癌剂发展的潜力。