Characterizing the Invasive Tumor Front of Aggressive Uterine Adenocarcinoma and Leiomyosarcoma

Abstract

The invasive tumor front (the tumor–host interface) is vitally important in malignant cell progression and metastasis. Tumor cell interactions with resident and infiltrating host cells and with the surrounding extracellular matrix and secreted factors ultimately determine the fate of the tumor. Herein we focus on the invasive tumor front, making an in-depth characterization of reticular fiber scaffolding, infiltrating immune cells, gene expression, and epigenetic profiles of classified aggressive primary uterine adenocarcinomas (24 patients) and leiomyosarcomas (11 patients). Sections of formalin-fixed samples before and after microdissection were scanned and studied. Reticular fiber architecture and immune cell infiltration were analyzed by automatized algorithms in colocalized regions of interest. Despite morphometric resemblance between reticular fibers and high presence of macrophages, we found some variance in other immune cell populations and distinctive gene expression and cell adhesion-related methylation signatures. Although no evident overall differences in immune response were detected at the gene expression and methylation level, impaired antimicrobial humoral response might be involved in uterine leiomyosarcoma spread. Similarities found at the invasive tumor front of uterine adenocarcinomas and leiomyosarcomas could facilitate the use of common biomarkers and therapies. Furthermore, molecular and architectural characterization of the invasive front of uterine malignancies may provide additional prognostic information beyond established prognostic factors.

Spatial transcriptomics technology in cancer research

“…The tumor interface, the invasion front for tumor cells to expand, is a critical region to uncover the tumor invasion and progression (5,(105)(106)(107). The intermediate zone between the tumor tissue and the non-tumor tissue has unique microenvironment, thus existing unique characteristics in cellcell interaction, cell composition and immune states (Table 2).…”

Integrating digital pathology with transcriptomic and epigenomic tools for predicting metastatic uterine tumor aggressiveness

“…A total of 24 uADC, 11 uLMS, 6 uADC lung metastases and 9 uLMS lung metastases (LM-uADC and LM-uLMS) were included in the study. We used formalin-fixed and paraffinembedded (FFPE) tissue samples from uADC and uLMS primary tumors (previously described in Sanegre et al (2021), with a particular focus on paired cases (primary tumors with their respective lung metastases). Tumors were classified according to the latest WHO criteria and were surgically staged and graded following the International Federation of Gynecology and Obstetrics (FIGO) classification and staging systems.…”

“…Stromatogenesis, the formation of new stroma at the ITF, disrupts the continuity of normal tissues, facilitating the invasion process. This newly formed tumorassociated stroma is composed of stromal cells and the extracellular matrix (ECM), which is biochemically distinct in composition (Sivridis, Giatromanolaki and Koukourakis, 2004;Sanegre et al, 2021). Specifically, the new ECM is characterized by increased deposition of fibrillar collagen and cross-links, leading to increased tissue stiffness and causing desmoplasia, typical of the tumor (Eble and Niland, 2019).…”

“…Reticulin fibers form an extensive branched network, with a mesh-like pattern, forming part of many organs, mainly as part of the basement membrane in epithelial tissue, in the basal lamina of adipose tissue and in locations with high cellular content, such as the endocrine glands, liver and bone marrow (Ushiki, 2002). They are found in high abundance in several disorders and tumors such as Castleman disease (Carbone et al, 2021), myeloproliferative neoplasms (Gleitz, Benabid and Schneider, 2021) and aggressive primary uADC and uLMS (Sanegre et al, 2021). Under the microscope, reticular fibers are indistinguishable from the other types in conventional stains, but they can be observed stained black with Gomori's silver impregnation method, a technique routinely employed for visualization and characterization in many pathology departments (Ushiki, 2002).…”

“…With the emergence of precision oncology, automated analysis of an ever-growing number of omics-generated biomarkers and the development of deep learning digital pathology models for their measurement in spatial context, all require methodological approaches for integrating the resulting data, which will bring insight into the molecular mechanisms leading to different pathways of original and metastatic tumor characterization in each patient (Mungenast et al, 2021). We recently characterized and compared the ITF of aggressive primary uADC and uLMS in a multicenter study, finding that despite morphometric resemblance between reticular fibers and high presence of macrophages, some variance could be observed in other immune cell populations, as well as distinctive gene expression and cell adhesion-related DNA methylation signatures (Sanegre et al, 2021). In this study, therefore, we used the same digital analysis, transcriptomic and epigenomic tools to investigate whether these changes are maintained in metastatic uADC and uLMS samples, and also compared them with the primary tumors.…”