Leukemic stem cells (LSCs) adhere to bone niches through adhesion molecules. These interactions, which are deeply reorganized in tumors, contribute to LSC resistance to chemotherapy and leukemia relapse. However, LSC adhesion mechanisms and potential therapeutic disruption using blocking antibodies remain largely unknown. Junctional adhesion molecule C (JAM-C, also known as JAM3) overexpression by LSCs correlates with increased leukemia severity, and thus constitutes a putative therapeutic target. Here, we took advantage of the ability of nanoscopy to detect single molecules with nanometric accuracy to characterize junctional adhesion molecule (JAM) dynamics at leuko-stromal contacts. Videonanoscopy trajectories were reconstructed using our dedicated multi-target tracing algorithm, pipelined with dual-color analyses (MTT2col). JAM-C expressed by LSCs engaged in transient interactions with JAM-B (also known as JAM2) expressed by stromal cells. JAM recruitment and colocalization at cell contacts were proportional to JAM-C level and reduced by a blocking anti-JAM-C antibody. MTT2col revealed, at single-molecule resolution, the ability of blocking antibodies to destabilize LSC binding to their niches, opening opportunities for disrupting LSC resistance mechanisms.

中文翻译：

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通过单分子追踪纳米镜分析正常和破坏的白血病干细胞与骨髓基质细胞的粘附。

白血病干细胞 (LSC) 通过粘附分子粘附在骨龛上。这些相互作用在肿瘤中深度重组，导致 LSC 对化疗和白血病复发的耐药性。然而，LSC 粘附机制和使用阻断抗体的潜在治疗中断在很大程度上仍然未知。LSC 的连接性粘附分子 C（JAM-C，也称为 JAM3）过表达与白血病严重程度增加相关，因此构成了一个推定的治疗靶点。在这里，我们利用纳米显微镜的能力以纳米精度检测单个分子，以表征白质基质接触处的连接粘附分子 (JAM) 动力学。使用我们专用的多目标跟踪算法重建视频纳米镜轨迹，并通过双色分析 (MTT2col) 进行流水线处理。LSC 表达的 JAM-C 与基质细胞表达的 JAM-B（也称为 JAM2）进行瞬时相互作用。JAM 募集和细胞接触处的共定位与 JAM-C 水平成正比，并被阻断性抗 JAM-C 抗体降低。MTT2col 以单分子分辨率揭示了阻断抗体破坏 LSC 与其壁龛结合的能力，为破坏 LSC 抗性机制提供了机会。