EpCAM-CD24+ circulating cells associated with poor prognosis in breast cancer patients.

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 (M0mts) 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.

Molecular subtype conversion in CTCs as indicator of treatment adequacy associated with metastasis-free survival in breast cancer.

Molecular subtype of breast cancer has a great clinical significance and used as one of the major criteria for therapeutic strategy. Recently, for anticancer therapy, the trend for oncologists is the predominant determination of biomarkers in the existing foci of the disease. In the case of adjuvant therapy prescribed for distant metastases prevention, CTCs could be a suitable object for investigation. CTCs as one of the factors responsible for tumor metastatic potential could be more convenient and informative for evaluation of hormone receptors, Ki-67 and HER2 expression, which are determine molecular subtype in breast cancer patient. In our study, we aimed to investigate the molecular subtype discordance between the primary tumor and CTCs in breast cancer patients. We established conversion of molecular subtype in most of the cases. Namely, conversion was detected in 90% of untreated patients and in 82% of breast cancer patients treated by neoadjuvant chemotherapy. At the same time, molecular subtype conversions in patients treated by neoadjuvant chemotherapy were more diverse. Molecular subtype conversions resulted more often in the unfavorable variants in circulating tumor cells. We stratified all patients according to the adequacy of treatment against converted CTCs molecular subtype. Our study revealed that good response to neoadjuvant chemotherapy observed in case of adequate therapy, namely, when chemotherapy scheme was sufficient against CTCs. It turned out that patients with inadequate therapy were characterized by decreased simulated 5-year metastasis-free survival compared to patients who received appropriate therapy. Thus, detection of molecular subtype conversion in circulating tumor cells could be a perspective tool for optimization of antitumor therapy.

Do tumor exosome integrins alone determine organotropic metastasis?

Metastasis is the most life-threatening event in cancer patients, so the key strategy to treat cancer should be preventing tumor spread. Predicting the site of probable hematogenous metastasis is important for determining the therapeutic algorithm that could prevent the spread of tumor cells. Certain hopes for solving this problem appeared owing to study showing the association between specific integrins on tumor exosomes surface and the site of future metastasis. Numerous experimental data indicate the ability of exosomes to transfer various phlogogenic factors to the target organ, which can lead to the formation of inflammatory foci. Studies of T-lymphocytes homing show that expression of various adhesion molecules including ligands for integrins highly increases on the endothelium during inflammation. Such a mechanism underlies not only in leukocyte transvasation, but, apparently, in the accumulation of bone marrow precursor cells and the formation of a premetastatic niche. This review summarizes the most significant data on the role exosomes to induce inflammation, which leads to the recruiting of bone marrow precursors and the establishment of premetastatic niches.

Intravasation as a Key Step in Cancer Metastasis.

Intravasation is a key step in cancer metastasis during which tumor cells penetrate the vessel wall and enter circulation, thereby becoming circulating tumor cells and potential metastatic seeds. Understanding the molecular mechanisms of intravasation is critically important for the development of therapeutic strategies to prevent metastasis. In this article, we review current data on the mechanisms of cancer cell intravasation into the blood and lymphatic vessels. The entry of mature thymocytes into the circulation and of dendritic cells into the regional lymph nodes is considered as example of intravasation under physiologically normal conditions. Intravasation in a pathophysiological state is illustrated by the reverse transendothelial migration of leukocytes into the bloodstream from the sites of inflammation mediated by the sphingosine 1-phosphate interaction with its receptors. Intravasation involves both invasion-dependent and independent mechanisms. In particular, mesenchymal and amoeboid cell invasion, as well as neoangiogenesis and vascular remodeling, are discussed to play a significant role in the entry of tumor cells to the circulation. Special attention is given to the contribution of macrophages to the intravasation via the CSF1/EGF (colony stimulating factor 1/epidermal growth factor) paracrine signaling pathway and the TMEM (tumor microenvironment of metastasis)-mediated mechanisms. Other mechanisms including intravasation of tumor cell clusters surrounded by the vessel wall elements, cooperative intravasation (entry of non-invasive tumor cells to the circulation following invasive tumor cells), and intravasation associated with the vasculogenic mimicry (formation of vascular channels by tumor cells) are also discussed. Novel intravasation-specific mechanisms that have not yet been described in the literature are suggested. The importance of targeted therapeutic strategies to prevent cancer intravasation is emphasized.

Different morphological structures of breast tumors demonstrate individual drug resistance gene expression profiles.

AIM: To identify gene expression profiles involved in drug resistance of different morphological structures (tubular, alveolar, solid, trabecular, and discrete) presented in breast cancer. MATERIAL AND METHODS: Ten patients with luminal breast cancer have been included. A laser microdissection-assisted microarrays and qRT-PCR were used to perform whole-transcriptome profiling of different morphological structures, to select differentially expressed drug response genes, and to validate their expression. RESULTS: We found 27 differentially expressed genes (p < 0.05) encoding drug uptake (SLC1A3, SLC23A2, etc.) and efflux (ABCC1, ABCG1, etc.) transporters, drug targets (TOP2A, TYMS, and Tubb3), and proteins that are involved in drug detoxification (NAT1 and ALDH1B1), cell cycle progression (CCND1, AKT1, etc.), apoptosis (CASP3, TXN2, etc.), and DNA repair (BRCA1 and USP11). Each type of structures showed an individual gene expression profile related to resistance and sensitivity to anticancer drugs. However, most of the genes (19/27; p < 0.05) were expressed in alveolar structures. Functional enrichment analysis showed that drug resistance is significantly associated with alveolar structures. Other structures demonstrated the similar number (10-13 out of 27) of expressed genes; however, the spectrum of resistance and sensitivity to different anticancer drugs varied. CONCLUSION: Different morphological structures of breast cancer show individual expression of drug resistance genes.

Types of Immune-Inflammatory Responses as a Reflection of Cell-Cell Interactions under Conditions of Tissue Regeneration and Tumor Growth.

Inflammatory infiltration of tumor stroma is an integral reflection of reactions that develop in response to any damage to tumor cells including immune responses to antigens or necrosis caused by vascular disorders. In this review, we use the term "immune-inflammatory response" (IIR) that allows us to give an integral assessment of the cellular composition of the tumor microenvironment. Two main types of IIRs are discussed: type 1 and 2 T-helper reactions (Th1 and Th2), as well as their inducers: immunosuppressive responses and reactions mediated by Th22 and Th17 lymphocytes and capable of modifying the main types of IIRs. Cellular and molecular manifestations of each IIR type are analyzed and their general characteristics and roles in tissue regeneration and tumor growth are presented. Since inflammatory responses in a tumor can also be initiated by innate immunity mechanisms, special attention is given to inflammation based on them. We emphasize that processes accompanying tissue regeneration are prototypes of processes underlying cancer progression, and these processes have the same cellular and molecular substrates. We focus on evidence that tumor progression is mainly contributed by processes specific for the second phase of "wound healing" that are based on the Th2-type IIR. We emphasize that the effect of various types of immune and stroma cells on tumor progression is determined by the ability of the cells and their cytokines to promote or prevent the development of Th1- or Th2-type of IIR. Finally, we supposed that the nonspecific influence on the tumor caused by the cytokine context of the Th1- or Th2-type microenvironment should play a decisive role for suppression or stimulation of tumor growth and metastasis.

Effect of small and radical surgical injury on the level of different populations of circulating tumor cells in the blood of breast cancer patients.

Circulating tumor cells (CTCs) constitute a heterogeneous population. Some tumor cells are cancer stem cells (CSCs), while others are in the process of the epithelial-mesenchymal transition (EMT); however, most CTCs are neither stem cells nor in the EMT. This prospective study of 22 patients with nonspecific-type invasive carcinoma of the breast identified different populations of CTCs by flow cytometry in the blood of patients before biopsy, after biopsy and after surgical tumor removal without neoadjuvant chemotherapy. The results showed that minor surgical injury (biopsy) was accompanied by a significant increase in the blood levels of CTCs without signs of the EMT or stemness (Epcam+CD45-CD44-CD24-Ncadh-) and CTCs with signs of stemness and without signs of the EMT (Epcam+CD45-CD44+CD24-Ncadh-). Our results suggest that minor surgical injury to a tumor contributes to the release of CTCs into the bloodstream, including a population of stem cells.