Tatiana S. Gerashchenko

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

Abstract 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.

Invasive and drug resistant expression profile of different morphological structures of breast tumors.

In order to understand invasive/adhesive and drug resistant properties of intratumor morphological heterogeneity of breast cancer, we compared the expression of genes responsible for the cell adhesion and for the drug resistance between distinct morphological structures of breast tumors. Tubular (hollow-like), alveolar (morula-like), trabecular, solid structures/patterns, and discrete (small) groups of tumor cells were isolated from invasive carcinoma of no special type (n=3) and invasive micropapillary carcinoma (n=1) of the breast using laser microdissection. The gene expression of cadherins, catenins, integrins, ABC transporters, GSTP1, and drug targets was analyzed using qRT-PCR. Expression of catenin genes was identified in almost all structures. In contrast, the expression of cadherin and integrin genes significantly varied depending on the morphological variant. Cadherin expression declined in the row: solid - alveolar and trabecular structures - discrete groups of tumor cells. Expression of integrins declined in the row: solid and alveolar - trabecular structures - discrete groups of tumor cells. For drug resistance genes, trabecular structures more often demonstrated activity of genes coding for ABC transporters compared to other morphological variants. These results indicate that intratumoral morphological heterogeneity in breast cancer correlates with expression profile of adhesion and drug resistance genes reflecting different patterns of invasive growth and responsiveness to chemotherapy.

Relationship between morphological and cytogenetic heterogeneity in invasive micropapillary carcinoma of the breast: a report of one case

Invasive micropapillary carcinoma (IMPC) is a rare (up to 2%) and aggressive form of breast cancer.1 ,2 IMPC shows high intratumoral morphological diversity, which represents the degree of cell differentiation, as well as the architectural and invasive growth patterns of tumour cells. Morphologically, these tumours are characterised by the presence of hollow-like (tubular) and morula-like (alveolar) structures of cuboidal-to-columnar neoplastic cells, which are surrounded by empty spaces (retraction clefts) and display an inversion of cell polarity, detected by aberrant localisation of glycoprotein MUC-1 at the stromal–basal surface.1 ,3 In addition, micropapillary tumour clusters can be represented by tumour cells arranged in solid patterns (structures), trabecular structures and discrete (small) groups.3–6 It has been suggested that morphological diversity of IMPC is related to chemotherapy resistance,7 whereas the presence of retraction clefts around tumour clusters is associated with increased lymphangiogenesis and lymph node metastasis.8 Considerable intratumour morphological heterogeneity in breast cancer most likely results from genetic and epigenetic instability of the tumour cells.9 ,10 Previously, the relationships between morphologically distinct components and specific chromosome aberrations have been found in metaplastic and invasive ductal breast carcinomas,11 ,12 the latter is now classified as invasive carcinoma of no special type (IC NST), and is the most common histological type of breast cancer.1 IMPC demonstrates a heterogeneous pattern of chromosome aberrations, and tends to be genetically a more complex disease than IC NST.11 ,12 IMPC more often harboured gains of chromosomes 1q, 8q, 17q and 20q, and losses of 1p, 8p, 13q, 16q and 22q,13 ,14 which were emphasised by Marchio and coauthors13 as previously associated with breast tumours of high histological grade. In contrast, concurrent gain of 1q and 16p and deletion of 16q, related to low …

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.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.

Inter- and intratumor heterogeneity in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is structurally complex system undergoing different molecular and phenotypic changes during tumor development. These changes can be represented by chromosomal and microsatellite instability, gene mutations, and variations in gene, protein expression patterns and morphology, and can operate together with alterations of the tumor cell epigenome and tumor microenvironment in the process of cancer clonal evolution, thus resulting in considerable intertumor (interpatient) and intratumor heterogeneity. In this chapter, we presented the basic information about the nature and the mechanisms of tumor heterogeneity in general and HCC heterogeneity in particular, focusing attention on the role of somatic mosaicism in the development of tumor diversity. To date, intertumor heterogeneity in HCC represented by differences between tumors of different patients has been characterized to comprise both well-known histological types and several molecular subtypes with specific genetic changes and therapeutic interventions. Intratumor heterogeneity of HCC was shown to include differences between tumors of the same origin or tumor cells within the same tumor and to be associated with cancer growth and progression. Moreover, HCCs were found to demonstrate the variability in the distribution of stromal and inflammatory cells in the tumor microenvironment, which also contributes to the biological behavior of tumors. Despite abundant data concerning intratumor heterogeneity in HCC, routine qualitative and quantitative criteria are not suggested to be applied in the capturing of the complete genomic landscape of cancer, and the assessment of the risk of cancer progression and therapy response. Summarizing all the data, we reviewed potential targets and methods for the assessment of intratumor heterogeneity in clinical practice.