The Department of General and Molecular Pathology, Cancer Research Institute, Tomsk National Research Medical Center, Russian Academy of Sciences, Tomsk, Russia.
The Laboratory of Molecular Therapy of Cancer, Cancer Research Institute, Tomsk National Research Medical Center, Russian Academy of Sciences, Tomsk, Russia.
Sci Rep. 2024 May 28;14(1):12245. doi: 10.1038/s41598-024-61516-2.
Following the discovery of circulating tumor cells (CTCs) in the peripheral blood of cancer patients, CTCs were initially postulated to hold promise as a valuable prognostic tool through liquid biopsy. However, a decade and a half of accumulated data have revealed significant complexities in the investigation of CTCs. A challenging aspect lies in the reduced expression or complete loss of key epithelial markers during the epithelial-mesenchymal transition (EMT). This likely hampers the identification of a pathogenetically significant subset of CTCs. Nevertheless, there is a growing body of evidence regarding the prognostic value of such molecules as CD24 expressing in the primary breast tumor. Herewith, the exact relevance of CD24 expression on CTCs remains unclear. We used two epithelial markers (EpCAM and cytokeratin 7/8) to assess the count of CTCs in 57 breast cancer patients, both with (M0) and without metastasis (M0) during the follow-up period, as well as in M1 breast cancer patients. However, the investigation of these epithelial markers proved ineffective in identifying cell population expressing different combinations of EpCAM and cytokeratin 7/8 with prognostic significance for breast cancer metastases. Surprisingly, we found CD24+ circulating cells (CCs) in peripheral blood of breast cancer patients which have no epithelial markers (EpCAM and cytokeratin 7/8) but was strongly associated with distant metastasis. Namely, the count of CD45-EpCAM-CK7/8-CD24+ N-cadherin-CCs was elevated in both groups of patients, those with existing metastasis and those who developed metastases during the follow-up period. Simultaneously, an elevation in these cell counts beyond the established threshold of 218.3 cells per 1 mL of blood in patients prior to any treatment predicted a 12-fold risk of metastases, along with a threefold decrease in distant metastasis-free survival over a 90-month follow-up period. The origin of CD45-EpCAM-CK7/8-CD24+ N-cadherin-CCs remains unclear. In our opinion their existence can be explained by two most probable hypotheses. These cells could exhibit a terminal EMT phenotype, or it might be immature cells originating from the bone marrow. Nonetheless, if this hypothesis holds true, it's worth noting that the mentioned CCs do not align with any of the recognized stages of monocyte or neutrophil maturation, primarily due to the presence of CD45 expression in the myeloid cells. The results suggest the presence in the peripheral blood of patients with metastasis (both during the follow-up period and prior to inclusion in the study) of a cell population with a currently unspecified origin, possibly arising from both myeloid and tumor sources, as confirmed by the presence of aneuploidy.
在癌症患者外周血中发现循环肿瘤细胞（CTC）后，CTC 最初被认为是通过液体活检作为有价值的预后工具。然而，经过十五年的积累数据，CTC 的研究存在显著的复杂性。一个具有挑战性的方面在于上皮-间充质转化（EMT）过程中关键上皮标志物的表达减少或完全丢失。这可能阻碍了对具有发病意义的 CTC 亚群的识别。然而，关于 CD24 在原发性乳腺癌中表达等分子的预后价值，已经有越来越多的证据。在此，CTC 上 CD24 表达的确切相关性尚不清楚。我们使用两种上皮标志物（EpCAM 和细胞角蛋白 7/8）来评估 57 例乳腺癌患者（包括随访期间有（M0）和无转移（M0）以及 M1 乳腺癌患者）的 CTC 计数。然而，这些上皮标志物的研究证明，在识别具有预后意义的乳腺癌转移的不同 EpCAM 和细胞角蛋白 7/8 组合表达的细胞群体方面是无效的。令人惊讶的是，我们在乳腺癌患者的外周血中发现了 CD24+循环细胞（CC），它们没有上皮标志物（EpCAM 和细胞角蛋白 7/8），但与远处转移强烈相关。也就是说，在两组患者中，即那些已经存在转移的患者和那些在随访期间发生转移的患者中，CD45-EpCAM-CK7/8-CD24+N-钙黏蛋白-CC 的数量均升高。同时，在患者接受任何治疗之前，这些细胞计数超过每 1ml 血液中 218.3 个细胞的既定阈值，预示着转移的风险增加 12 倍，并且在 90 个月的随访期间，远处无转移生存时间减少三倍。CD45-EpCAM-CK7/8-CD24+N-钙黏蛋白-CC 的来源尚不清楚。我们认为，它们的存在可以用两个最可能的假设来解释。这些细胞可能表现出终末 EMT 表型，或者它们可能是起源于骨髓的不成熟细胞。尽管如此，如果这个假设成立，值得注意的是，提到的 CC 与单核细胞或中性粒细胞成熟的任何已知阶段都不相符，主要是由于髓样细胞中存在 CD45 表达。结果表明，在有转移的患者（包括在随访期间和纳入研究之前）的外周血中存在一种目前尚未确定来源的细胞群，可能来自髓样细胞和肿瘤源，这一点得到了非整倍体的存在的证实。
