School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea.
School of Pharmacy, Sungkyunkwan University, Suwon, Republic of Korea
In Vivo. 2022 Sep-Oct;36(5):2105-2115. doi: 10.21873/invivo.12936.
BACKGROUND/AIM: Few studies have examined the correlation between pyruvate kinase M2 (PKM2) overexpression and triple-negative breast cancer (TNBC). TNBC is considered incurable with the currently available treatments, highlighting the need for alternative therapeutic targets.
PKM2 expression was examined immunohistochemically in human breast tumor samples. Furthermore, we studied the effect of three PKM2 inhibitors (gliotoxin, shikonin, and compound 3K) in the MDA-MB-231 TNBC cell line.
PKM2 overexpression correlates with TNBC. Interestingly, most TNBC tissues showed increased levels of PKM2 compared to those of receptor-positive breast cancer tissues. This suggests that PKM2 overexpression is an important factor in the development of TNBC. MDA-MB-231 TNBC cells are resistant to anticancer drugs, such as vincristine (VIC) compared to other cancer cells. We found that the recently developed PKM2 inhibitor gliotoxin sensitized MDA-MB-231 cells at a relatively low dose to the same extent as the known PKM2 inhibitor shikonin, suggesting that PKM2 inhibitors could be an effective treatment for TNBC. Detailed sensitization mechanisms were also analyzed. Both gliotoxin and shikonin highly increased late apoptosis in MDA-MB-231 cells, as revealed by annexin V staining. However, MDA-MB-231 cells with high cellular density inhibited the sensitizing effect of PKM2 inhibitors; therefore, we investigated ways to overcome this inhibitory effect. We found that gliotoxin+shikonin co-treatment highly increased toxicity in MDA-MB-231 cells with high density, whereas either VIC+gliotoxin or VIC+shikonin were not effective. Thus, combination therapy with various PKM2 inhibitors may be more effective than combination therapy with anticancer drugs. Gliotoxin+shikonin co-treatment did not increase S or G arrest in cells, suggesting that the co-treatment showed a high increase in apoptosis without S or G arrest. We confirmed that another recently developed PKM2 inhibitor compound 3K had similar mechanisms of sensitizing MDA-MB-231 cells, suggesting that PKM2 inhibitors have similar sensitization mechanisms in TNBC.
PKM2 is a regulator of the oncogenic function of TNBC, and combination therapy with various PKM2 inhibitors may be effective for high-density TNBC. Targeting PKM2 in TNBC lays the foundation for the development of PKM2 inhibitors as promising anti-TNBC agents.
背景/目的：很少有研究探讨丙酮酸激酶 M2（PKM2）过表达与三阴性乳腺癌（TNBC）之间的相关性。目前的治疗方法认为 TNBC 是无法治愈的，这突显了需要替代的治疗靶点。
我们通过免疫组织化学方法检测了人乳腺癌肿瘤样本中 PKM2 的表达情况。此外，我们还在 MDA-MB-231 TNBC 细胞系中研究了三种 PKM2 抑制剂（Gliotoxin、Shikonin 和化合物 3K）的作用。
PKM2 过表达与 TNBC 相关。有趣的是，与受体阳性乳腺癌组织相比，大多数 TNBC 组织中 PKM2 的水平升高。这表明 PKM2 过表达是 TNBC 发展的一个重要因素。与其他癌细胞相比，MDA-MB-231 TNBC 细胞对长春新碱（VIC）等抗癌药物具有耐药性。我们发现，最近开发的 PKM2 抑制剂 Gliotoxin 以相对较低的剂量与已知的 PKM2 抑制剂 Shikonin 一样，使 MDA-MB-231 细胞敏感，这表明 PKM2 抑制剂可能是治疗 TNBC 的有效方法。我们还分析了详细的敏化机制。通过 Annexin V 染色发现，Gliotoxin 和 Shikonin 均可使 MDA-MB-231 细胞的晚期凋亡明显增加。然而，高细胞密度的 MDA-MB-231 细胞抑制了 PKM2 抑制剂的敏化作用；因此，我们研究了克服这种抑制作用的方法。我们发现，Gliotoxin+Shikonin 联合治疗可使高细胞密度的 MDA-MB-231 细胞毒性显著增加，而 VIC+Gliotoxin 或 VIC+Shikonin 则无效。因此，与抗癌药物联合治疗相比，多种 PKM2 抑制剂的联合治疗可能更有效。Gliotoxin+Shikonin 联合治疗并未增加细胞的 S 或 G 期阻滞，这表明联合治疗可在不发生 S 或 G 期阻滞的情况下，使细胞凋亡明显增加。我们证实，另一种最近开发的 PKM2 抑制剂化合物 3K 对 MDA-MB-231 细胞具有类似的敏化机制，表明 PKM2 抑制剂在 TNBC 中具有类似的敏化机制。
PKM2 是 TNBC 致癌功能的调节剂，与各种 PKM2 抑制剂联合治疗可能对高细胞密度的 TNBC 有效。针对 TNBC 中的 PKM2 为开发有前途的抗 TNBC 药物的 PKM2 抑制剂奠定了基础。
