Medical Laboratories Technology Department, College of Applied Medical Sciences, Taibah University, Madinah, P.O. Box 41477, Saudi Arabia.
Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, AB T6G 2E1, Canada.
Int J Mol Sci. 2021 Jan 18;22(2):893. doi: 10.3390/ijms22020893.
We have previously shown that the Wnt canonical pathway (WCP) is constitutively active in most cases of mantle cell lymphoma (MCL). Here, we aimed to elucidate the mechanisms underlying this biochemical deregulation. We hypothesized that gene methylation/silencing of WIF1 (Wnt inhibitory factor-1), a physiologic inhibitor of WCP, contributes to the deregulation of WCP and promotes cell growth in MCL. In support of this hypothesis, we found that the expression of WIF1 was detectable in none of the 4 MCL cell lines, and in only 2 of 5 tumors (40%) examined. Using methylation-specific PCR, we found evidence of gene methylation of WIF1 in 4 of 5 cell lines (80%) and in 24 of 29 (82%) tumors. The addition of the demethylation agent 5-aza-2'-deoxycytidine to Mino and JeKo-1, two WIF1-negative cell lines, restored the expression of WIF1 mRNA in these cells. Gene transfection of WIF1 into JeKo-1 and Mino cells significantly reduced cell growth, and this finding correlated with substantial downregulations of various proteins in WCP, such as β-catenin and pGSK-3β. In conclusion, our results support the concept that gene methylation/silencing of WIF1 is a frequent event in MCL, and this abnormality contributes to the aberrant activation of WCP. These results have provided further evidence that aberrant Wnt signaling is pathogenetically important in MCL and it may represent a potential therapeutic target.
我们之前已经表明，在大多数套细胞淋巴瘤（MCL）病例中，Wnt 经典途径（WCP）是持续激活的。在这里，我们旨在阐明这种生化失调的机制。我们假设 WIF1（Wnt 抑制因子-1）的基因甲基化/沉默，WCP 的一种生理性抑制剂，有助于 WCP 的失调，并促进 MCL 中的细胞生长。为了支持这一假说，我们发现 4 种 MCL 细胞系中均检测不到 WIF1 的表达，在 5 种肿瘤中仅有 2 种（40%）检测到。使用甲基化特异性 PCR，我们发现 5 种细胞系中的 WIF1 基因甲基化证据在 4 种（80%）和 29 种肿瘤中的 24 种（82%）中存在。在 WIF1 阴性的 Mino 和 JeKo-1 两种细胞系中添加去甲基化剂 5-aza-2'-脱氧胞苷，可恢复这些细胞中 WIF1 mRNA 的表达。WIF1 基因转染到 JeKo-1 和 Mino 细胞中显著降低了细胞生长，这一发现与 WCP 中的各种蛋白（如β-catenin 和 pGSK-3β）的显著下调相关。总之，我们的结果支持这样一种概念，即 WIF1 的基因甲基化/沉默是 MCL 中的一种常见事件，这种异常有助于 WCP 的异常激活。这些结果进一步证明了异常的 Wnt 信号在 MCL 中具有重要的发病机制作用，它可能代表一个潜在的治疗靶点。
