Identification and Morphological Characterization of Features of Circulating Cancer-Associated Macrophage-like Cells (CAMLs) in Endometrial Cancers

SIMPLE SUMMARY: Circulating cells in the blood of cancer patients with solid tumors are known to provide clinically relevant information about treatment response, tumor progression, metastasis, and the development of drug resistance. We identify for the first time the distinctive morphological characterization of endometrial giant macrophage-like cells, called CAMLs, in the context of the presence of circulating tumor cells in patients. Two distinct size-based subtypes of CAMLs, <20 µm (tiny) and >20 µm (giant), were demonstrated. The giant CAMLs have distinctive polymorphic morphologies with mononuclear or fused polynuclear structures, including (1) apoptotic CAMLs; (2) CAML–WBC doublets; (3) conjoined CAMLs; (4) CAML–WBC clusters; and (5) circulating tumor cell–CAML–WBC clusters. In enumerating CAMLs and circulating tumor cells simultaneously, we observed that all circulating tumor cell-positive patients are also positive for CAMLs, in contrast to 55% of patients out of all CAML-positive patients that were found positive for circulating tumor cells. ABSTRACT: The blood of patients with solid tumors contains circulating tumor-associated cells, including epithelial cells originating from the tumor mass, such as circulating tumor cells (CTCs), or phagocytic myeloid cells (differentiated monocytes), such as circulating cancer-associated macrophage-like cells (CAMLs). We report for the first time the identification and in-depth morphologic characterization of CAMLs in patients with endometrial cancers. We isolated CAMLs by size-based filtration on lithographically fabricated membranes followed by immunofluorescence, using a CD45+/CK 8,18,19+/EpCAM+/CD31+/macrophage-like nuclear morphology, from > 70 patients. Irrespective of the histological and pathological parameters, 98% of patients were positive for CAMLs. Two size-based subtypes of CAMLs, <20 µm (tiny) and >20 µm (giant) CAMLs, of distinctive polymorphic morphologies with mononuclear or fused polynuclear structures in several morphological states were observed, including apoptotic CAMLs, CAML–WBC doublets, conjoined CAMLs, CAML–WBC clusters, and CTC–CAML–WBC clusters. In contrast, CAMLs were absent in patients with non-neoplastic/benign tumors, healthy donors, and leucopaks. Enumerating CTCs simultaneously from the same patient, we observed that CTC-positive patients are positive for CAMLs, while 55% out of all CAML-positive patients were found positive for CTCs. Our study demonstrated for the first time the distinctive morphological characteristics of endometrial CAMLs in the context of the presence of CTCs in patients.