Metastasis prevention: How to catch metastatic seeds.

Despite considerable advances in the evolution of anticancer therapies, metastasis still remains the main cause of cancer mortality. Therefore, current strategies for cancer cure should be redirected towards prevention of metastasis. Targeting metastatic pathways represents a promising therapeutic opportunity aimed at obstructing tumor cell dissemination and metastatic colonization. In this review, we focus on preclinical studies and clinical trials over the last five years that showed high efficacy in suppressing metastasis through targeting lymph node dissemination, tumor cell extravasation, reactive oxygen species, pre-metastatic niche, exosome machinery, and dormancy.

Spatial Profile of Tumor Microenvironment in PD-L1-Negative and PD-L1-Positive Triple-Negative Breast Cancer.

The problem of finding more precise stratification criteria for identifying the cohort of patients who would obtain the maximum benefit from immunotherapy is acute in modern times. In our study were enrolled 18 triple-negative breast cancer patients. The Ventana SP142 test was used for PD-L1 detection. Spatial transcriptomic analysis by 10x Genomics was used to compare PD-L1-positive and PD-L1-negative tumors. The seven-color multiplex immunofluorescence (by Akoya) was used for the detection of the type of cells that carried the PD1 receptor and the PD-L1 ligand. Using pathway analysis, we showed that PD-L1-positive tumors demonstrate signatures of a cell response to cytokines, among others, and PD-L1-negative tumors demonstrate signatures of antigen presentation. PD-L1-positive and PD-L1-negative tumors have different tumor microenvironment (TME) compositions according to CIBERSORT analysis. Multiplex immunohistochemistry (IHC) confirmed the prevalence of PD1-negative M2 macrophages and PD1-negative T lymphocytes in PD-L1-positive tumors. PD-L1-positive tumors are not characterized by direct contact between cells carrying the PD1 receptor and the PD-L1 ligand. So, the absence of specific immune reactions against the tumor, predominance of pro-tumor microenvironment, and rare contact between PDL1 and PD1-positive cells may be the potential reasons for the lack of an immune checkpoint inhibitor (ICI) effect in triple-negative breast cancer patients.

Heterogeneity of Circulating Epithelial Cells in Breast Cancer at Single-Cell Resolution: Identifying Tumor and Hybrid Cells.

Circulating tumor cells and hybrid cells formed by the fusion of tumor cells with normal cells are leading players in metastasis and have prognostic relevance. This study applies single-cell RNA sequencing to profile CD45-negative and CD45-positive circulating epithelial cells (CECs) in nonmetastatic breast cancer patients. CECs are represented by transcriptionally-distinct populations that include both aneuploid and diploid cells. CD45- CECs are predominantly aneuploid, but one population contained more diploid than aneuploid cells. CD45+ CECs mostly diploid: only two populations have aneuploid cells. Diploid CD45+ CECs annotated as different immune cells, surprisingly harbored many copy number aberrations, and positively correlated to tumor grade. It is noteworthy that cancer-associated signaling pathways areabundant only in one aneuploid CD45- CEC population, which may represent an aggressive subset of circulating tumor cells. Thus, CD45- and CD45+ CECs are highly heterogeneous in breast cancer patients and include aneuploid cells, which are most likely circulating tumor and hybrid cells, respectively, and diploid cells. DNA ploidy analysis can be an effective instrument for identifying tumor and hybrid cells among CECs. Further follow-up study is needed to determine which subsets of circulating tumor and hybrid cells contribute to breast cancer metastasis.

Premalignant Changes in the Bronchial Epithelium Are Prognostic Factors of Distant Metastasis in Non-Small Cell Lung Cancer Patients.

BACKGROUND: The study assessed the possibility of dividing patients into groups based on the assessment of morphological changes in the epithelium of small-caliber bronchi located near the primary tumor in order to predict high and low risks of distant metastasis of non-small cell lung cancer. METHODS: In 171 patients with non-small cell lung cancer (T1-4N0-3M0) in small-caliber bronchi taken at a distance of 3-5 cm from the tumor, various variants of morphological changes in the bronchial epithelium (basal cell hyperplasia (BCH), squamous cell metaplasia (SM), and dysplasia (D)) were assessed. Long-term results of treatment, namely, distant metastasis, were assessed after 2 and 5 years. RESULTS: During the follow-up period, distant metastases were found in 35.1% (60/171) of patients. Most often, they were observed in patients of the high-risk group: BCH+SM-D- (51.6%, 40/95) and BCH-SM+D+ (54.4%, 6/11). Less often, distant metastases were observed in low-risk group patients: BCH+SM+D- (6.7%, 3/45) and BCH-SM-D- (10.0%, 2/20). Tumor size, grade, and stage were significant predictors of metastasis only in the high-risk group. The 5-year metastasis-free survival was better in the low-risk group of distant metastases. CONCLUSIONS: Isolated BCH or dysplasia in small bronchi distant from foci of tumor is associated with a high-risk distant metastasis and less 5-year metastasis-free survival.

Prognosis of Different Types of Non-Small Cell Lung Cancer Progression: Current State and Perspectives.

Despite advances in diagnostics and therapy of non-small cell lung cancer (NSCLC), the problem of prognosis and prevention of tumor progression is still highly important. Even if NSCLC is diagnosed in the early stages, almost a quarter of patients develop relapse; most of them die from recurrent disease. A large number of different markers have been proposed to predict the risk of NSCLC progression; however, none of them are used in clinical practice. It is obvious that this situation is related to the economic and methodological complexity of the proposed markers and/or their insufficient efficiency due to a lack of effective study models and tumor heterogeneity. Another reason may be that potential markers are developed for NSCLC progression in general, which is represented by at least four pathogenetically-distinct processes: synchronous lymph node metastasis, local, regional, and distant recurrence. In this review, we summarize data from published literature on clinicopathological, genetic, and molecular factors associated with different types of NSCLC progression and emphasize challenges and approaches to developing prognostic factors. In conclusion, we highlight the importance of further studies to reveal molecular mechanisms of NSCLC progression and the need for differential analysis of markers of local, regional, and distant recurrences for disease prognosis.

Neoadjuvant chemotherapy combined with intraoperative radiotherapy is effective to prevent recurrence in high-risk non-small cell lung cancer (NSCLC) patients.

BACKGROUND: Basal cell hyperplasia (BCH) and squamous metaplasia (SM) in the small bronchi distant from the tumor is associated with a high risk of non-small cell lung cancer (NSCLC) recurrence. Here, we assessed whether neoadjuvant chemotherapy (NAC), intraoperative radiotherapy (IORT), or adjuvant chemotherapy (AC) is effective to prevent recurrence in NSCLC patients (n=171) with different premalignant lesions in the small bronchi. METHODS: BCH, SM, and dysplasia (D) were identified in the samples of lung tissue distant from the tumor. NSCLC patients were treated by surgery, different combinations of NAC and IORT, and AC. RESULTS: Based on the type of bronchial lesions, NSCLC patients were classified into four groups: BCH+SM-D- (55.6%, 95/171), BCH+SM+D- (26.3%; 45/171), BCH-SM+D+ (6.4%, 11/171), and BCH-SM-D- (11.7%, 20/171). During 5 years, recurrent carcinoma was found in 13.4% (23/171) of patients and represented by metachronous metastases in the thoracic lymph nodes (82.6%, 19/23) and by a relapse in the bronchial stump (17.4%, 4/23). Recurrence was frequent in BCH+SM+D- patients (87.0%, 20/23), rare in BCH+SM-D- and BCH-SM-D- patients (13.0%, 3/23), and absent in BCH-SM+D+ patients (0/23). The 5-year recurrence-free survival was also shorter in BCH+SM+D- patients (HR 27.35; 95% CI: 6.31-118.48; P<0.0001). In the high-risk (BCH+SM+D-) group, recurrence occurred mainly in cases without NAC and IORT (88.2%, 15/17) and was absent (0/15) when these therapies were combined. NAC- and IORT-negative patients also showed poor overall survival (HR 4.35; 95% CI: 1.96-9.66; P<0.0001) and tended to have decreased recurrence-free survival (P=0.075). Importantly, the recurrence rate was not different between AC-treated and AC-naïve BCH+SM+D- patients. CONCLUSIONS: The combination of NAC and IORT is an effective strategy to prevent recurrence in high-risk NSCLC patients.

The Activity of KIF14, Mieap, and EZR in a New Type of the Invasive Component, Torpedo-Like Structures, Predetermines the Metastatic Potential of Breast Cancer.

Intratumor morphological heterogeneity reflects patterns of invasive growth and is an indicator of the metastatic potential of breast cancer. In this study, we used this heterogeneity to identify molecules associated with breast cancer invasion and metastasis. The gene expression microarray data were used to identify genes differentially expressed between solid, trabecular, and other morphological arrangements of tumor cells. Immunohistochemistry was applied to evaluate the association of the selected proteins with metastasis. RNA-sequencing was performed to analyze the molecular makeup of metastatic tumor cells. High frequency of metastases and decreased metastasis-free survival were detected in patients either with positive expression of KIF14 or Mieap or negative expression of EZR at the tips of the torpedo-like structures in breast cancers. KIF14- and Mieap-positive and EZR-negative cells were mainly detected in the torpedo-like structures of the same breast tumors; however, their transcriptomic features differed. KIF14-positive cells showed a significant upregulation of genes involved in ether lipid metabolism. Mieap-positive cells were enriched in genes involved in mitophagy. EZR-negative cells displayed upregulated genes associated with phagocytosis and the chemokine-mediated signaling pathway. In conclusion, the positive expression of KIF14 and Mieap and negative expression of EZR at the tips of the torpedo-like structures are associated with breast cancer metastasis.

Gene Expression Profiling Revealed 2 Types of Bronchial Basal Cell Hyperplasia and Squamous Metaplasia With Different Progression Potentials.

The premalignant process preceding squamous cell lung cancer is not inevitable; it can stop at any of the bronchial lesions: basal cell hyperplasia (BCH), squamous metaplasia (SM), and dysplasia and then progress or regress. At present, the mechanisms underlying the progression of the bronchial lesions remain undefined. Previously, we hypothesized that bronchial lesions that presented individually or combined with each other in the bronchi of lung cancer patients mirror the different "scenarios" of the premalignant process: individual BCH-the stoppage at the stage of hyperplasia, BCH plus SM-the progression of hyperplasia to metaplasia, and SM plus dysplasia-the progression of metaplasia to dysplasia. In this study, we analyzed gene expression profiles of BCH, SM, and dysplasia depending on their cooccurrence in the bronchi of lung cancer patients. The immune response gene expression was found to be a key difference between the individual BCH and BCH combined with SM lesions and a potential mechanism that determines the progression of hyperplasia to metaplasia. Upregulation of the cell cycle and downregulation of the cilium assembly genes mainly distinguished SM that copresented with dysplasia from SM that copresented with BCH and is a probable mechanism of the progression of metaplasia to dysplasia. Dysplasia showed mainly overexpression of the cell division genes and underexpression of the inflammation genes. Thus, this study demonstrates the significant gene expression differences between the premalignant lesions depending on their cooccurrence in the bronchi and sheds light on the mechanisms of the precancerous process preceding squamous cell lung cancer.

Markers of Cancer Cell Invasion: Are They Good Enough?

Invasion, or directed migration of tumor cells into adjacent tissues, is one of the hallmarks of cancer and the first step towards metastasis. Penetrating to adjacent tissues, tumor cells form the so-called invasive front/edge. The cellular plasticity afforded by different kinds of phenotypic transitions (epithelial-mesenchymal, collective-amoeboid, mesenchymal-amoeboid, and vice versa) significantly contributes to the diversity of cancer cell invasion patterns and mechanisms. Nevertheless, despite the advances in the understanding of invasion, it is problematic to identify tumor cells with the motile phenotype in cancer tissue specimens due to the absence of reliable and acceptable molecular markers. In this review, we summarize the current information about molecules such as extracellular matrix components, factors of epithelial-mesenchymal transition, proteases, cell adhesion, and actin cytoskeleton proteins involved in cell migration and invasion that could be used as invasive markers and discuss their advantages and limitations. Based on the reviewed data, we conclude that future studies focused on the identification of specific invasive markers should use new models one of which may be the intratumor morphological heterogeneity in breast cancer reflecting different patterns of cancer cell invasion.

Clinically relevant morphological structures in breast cancer represent transcriptionally distinct tumor cell populations with varied degrees of epithelial-mesenchymal transition and CD44+CD24- stemness.

Intratumor morphological heterogeneity in breast cancer is represented by different morphological structures (tubular, alveolar, solid, trabecular, and discrete) and contributes to poor prognosis; however, the mechanisms involved remain unclear. In this study, we performed 3D imaging, laser microdissection-assisted array comparative genomic hybridization and gene expression microarray analysis of different morphological structures and examined their association with the standard immunohistochemistry scorings and CD44+CD24- cancer stem cells. We found that the intratumor morphological heterogeneity is not associated with chromosomal aberrations. By contrast, morphological structures were characterized by specific gene expression profiles and signaling pathways and significantly differed in progesterone receptor and Ki-67 expression. Most importantly, we observed significant differences between structures in the number of expressed genes of the epithelial and mesenchymal phenotypes and the association with cancer invasion pathways. Tubular (tube-shaped) and alveolar (spheroid-shaped) structures were transcriptionally similar and demonstrated co-expression of epithelial and mesenchymal markers. Solid (large shapeless) structures retained epithelial features but demonstrated an increase in mesenchymal traits and collective cell migration hallmarks. Mesenchymal genes and cancer invasion pathways, as well as Ki-67 expression, were enriched in trabecular (one/two rows of tumor cells) and discrete groups (single cells and/or arrangements of 2-5 cells). Surprisingly, the number of CD44+CD24- cells was found to be the lowest in discrete groups and the highest in alveolar and solid structures. Overall, our findings indicate the association of intratumor morphological heterogeneity in breast cancer with the epithelial-mesenchymal transition and CD44+CD24- stemness and the appeal of this heterogeneity as a model for the study of cancer invasion.

Intratumoral heterogeneity of macrophages and fibroblasts in breast cancer is associated with the morphological diversity of tumor cells and contributes to lymph node metastasis.

Recent studies have highlighted the heterogeneity of the tumor microenvironment (ME) and the importance of its analysis to the understanding of its impact on clinical outcomes. In this study, we aimed to analyze the intratumoral distribution of macrophages and fibroblasts in breast cancer (BC) based on the morphological diversity of tumor cells (tubular, alveolar, solid, trabecular and discrete structures) and the clinicopathological parameters of the disease. Thirty-six patients with invasive breast carcinoma of no special type were included in the study. The distribution of macrophages and fibroblasts in the MEs of different morphological structures was assessed using laser microdissection-assisted quantitative RT-PCR analysis of marker genes and double immunofluorescence staining for the CD68, RS1, aSMA, and FAP proteins. Gene expression microarrays were used to determine the expression of genes involved in the regulation of macrophage and fibroblast phenotypes in different morphological structures. We found that different macrophage and fibroblast subpopulations were simultaneously observed in the MEs of morphologically distinct structures but that the frequency of their detection and number of cells detected varied significantly among these structures. In particular, macrophages and fibroblasts were more frequently detected in the ME of solid structures and were rarely observed in tubular structures. A high number of CD68+RS1+ macrophages in the ME of solid structures was found to be associated with an increased frequency of lymph node metastasis in luminal B HER2- BC. In contrast, in luminal B HER2+ BC, lymph node involvement was related to the high representation of aSMA+FAP+ fibroblasts around trabecular structures. Morphologically distinct structures differed in the mechanisms regulating the macrophage and fibroblast phenotypes. The highest number of overexpressed genes controlling macrophage and fibroblast functions was observed in discrete groups of tumor cells, and the lowest number was observed in alveolar and solid structures. Taken together, our findings indicate the heterogeneous distribution of macrophages and fibroblasts in breast tumors and its close relation to the intratumoral morphological diversity of BC and contribution to lymph node metastasis.

Recurrence of squamous cell lung carcinoma is associated with the co-presence of reactive lesions in tumor-adjacent bronchial epithelium.

Recurrences occur in 30 % of lung cancer patients after radical therapy; however, known prognostic factors are not always effective. In this study, we investigated whether the frequency of squamous non-small cell lung cancer (NSCLC) recurrence depends on the presence of reactive lesions in tumor-adjacent bronchial epithelium. Specimens of adjacent lung tissue from 104 patients with squamous NSCLC were used for the determination of basal cell hyperplasia (BCH) and squamous metaplasia (SM) and for the analysis of the expression of Ki-67, p53, Bcl-2, and CD138. We found that recurrence was observed in 36.7 % of patients with BCH combined with SM (BCH + SM+) in the same bronchus, compared with 1.8 % in patients with isolated BCH (BCH + SM-; odds ratio (OR) 31.26, 95 % confidence interval (CI) 3.77-258.60; p = 0.00002). The percentage of Ki-67-positive cells was significantly higher in BCH + SM+ than in BCH + SM- (34.9 vs. 18.3 %; effect size 2.86, 95 % CI 2.23-3.47; p = 0.003). P53 expression was also more significant in BCH + SM+ than in BCH + SM- (14.4 vs. 9.6 %; effect size 1.22, 95 % CI 0.69-1.76; p = 0.0008). In contrast, CD138 expression was lower in BCH + SM+ than in BCH + SM- (21.8 vs. 38.5 %; effect size -6.26, 95 % CI -7.31 to -5.22; p = 0.003). Based on our results, we concluded that the co-presence of reactive bronchial lesions is associated with the development of recurrent squamous NSCLC and may be a negative prognostic indicator. In addition, significant differences in Ki-67, p53, and CD138 expression exist between isolated BCH and BCH combined with SM that probably reflect part of biological differences, which could relate to the mechanism of lung cancer recurrence.

Intratumoral morphological heterogeneity of breast cancer: neoadjuvant chemotherapy efficiency and multidrug resistance gene expression.

In this study, the influence of intratumoral morphological heterogeneity of breast cancer on neoadjuvant chemotherapy (NAC) efficiency was investigated. In particular, we analysed the association of NAC response and pre- and post-NAC expression of the main multidrug resistance (MDR) genes--ABCB1, ABCC1, ABCC5, ABCG1, and ABCG2, with the presence of different morphological structures in breast tumors. In addition, the expression of MDR genes was investigated in different morphological structures and in their microenvironment by comparing probes obtained using laser microdissection. The results of this study showed that tumors with alveolar structures were more frequently NAC-nonresponsive than cases without this structural type (p = 0.0028, Bonferroni-corrected p = 0.014). The presence of trabecular structures in breast tumors was also associated with chemoresistance (p = 0.0272, Bonferroni-corrected p = 0.136). High expression of MDR genes was not found in alveolar structures (including their microenvironment) and in tumors containing this structural type. In contrast, more active MDR genes and expression of the ABCB1 gene were found only in trabecular structures. Taken together, our data indicate that breast tumors with alveolar structures possess resistance to NAC, which is not related to high expression of MDR genes, whereas chemoresistance of tumors with trabecular structures can depend on the expression level of ABCB1.

Phenotypic drift as a cause for intratumoral morphological heterogeneity of invasive ductal breast carcinoma not otherwise specified.

Invasive ductal carcinoma (IDC) not otherwise specified (NOS), the most common type of breast cancer, demonstrates great intratumoral morphological heterogeneity, which encompasses the presence of different types of morphological structures-tubular, trabecular, solid, and alveolar structures and discrete groups of tumor cells, the origins of which remain unclear at present. In this study of 162 IDC NOS patients, we investigated whether the distribution of different types of morphological structures is related to the basic clinicopathological parameters of IDC NOS. Our results showed that in patients with only one type of tumor structure, the presence of any one of the five types was equally probable; however, cases with two types of structures were more likely to contain trabecular structures than the other four types. The development of intratumoral morphological heterogeneity was not associated with menopausal status, tumor size, histological grade, hematogenic metastasis, or recurrence. However, the number of different types of morphological structures was significantly higher in luminal tumors than in triple-negative tumors. An increase in the frequency of lymph node metastasis correlated with the increased number of different types of structures in breast tumors; however, in contrast to premenopausal patients, this association was explained by the presence of alveolar structures in postmenopausal women. In addition, we showed a significant decrease in the numbers of positive lymph nodes in tumors with high numbers of morphological variants. The frequency of lymph node metastases and the number of positive nodes were generally independent features and formed by different mechanisms. Based on the evidence, the term "phenotypic drift" has been designated as the basis for the development of intratumoral morphological heterogeneity of IDC NOS.