Proteoglycans Determine the Dynamic Landscape of EMT and Cancer Cell Stemness

Expression of CD44 is associated with aggressiveness in seminomas

BACKGROUND

Testicular germ cell tumors (TGCTs) exhibit diverse biological and pathological features and are divided in two main types, seminomas and nonseminomatous germ cell tumors (NSGCTs). CD44 is a cell surface receptor, which is highly expressed in malignancies and is implicated in tumorigenesis affecting cell-matrix interactions and cell signaling.

METHODS AND RESULTS

Here, we examined the expression of CD44 in tumor cell lines and in patients' material. We found that CD44 is over-expressed in TGCTs compared to normal tissues. Immunohistochemical staining in 71 tissue specimens demonstrated increased expression of CD44 in some patients, whereas CD44 was absent in normal tissue. In seminomas, a high percentage of tumor and stromal cells showed cytoplasmic and/or cell surface staining for CD44 as well as increased staining for CD44 in the tumor stroma was found in some cases. The increased expression of CD44 either in tumor cells or in stromal components was associated with tumor size, nodal metastasis, vascular/lymphatic invasion, and disease stage only in seminomas. The increased stromal expression of CD44 in TGCTs was positively associated with angiogenesis.

CONCLUSIONS

CD44 may exhibit diverse biological functions in seminomas and NSGCTs. The expression of CD44 in tumor cells as well as in tumor stroma fosters an aggressive phenotype in seminomas and should be considered in disease treatment.

The exostosin glycosyltransferase 1/STAT3 axis is a driver of breast cancer aggressiveness

The epithelial-mesenchymal transition (EMT) program is crucial for transforming carcinoma cells into a partially mesenchymal state, enhancing their chemoresistance, migration, and metastasis. This shift in cell state is tightly regulated by cellular mechanisms that are not yet fully characterized. One intriguing EMT aspect is the rewiring of the proteoglycan landscape, particularly the induction of heparan sulfate proteoglycan (HSPG) biosynthesis. This proteoglycan functions as a co-receptor that accelerates cancer-associated signaling pathways through its negatively-charged residues. However, the precise mechanisms through which EMT governs HSPG biosynthesis and its role in cancer cell plasticity remain elusive. Here, we identified exostosin glycosyltransferase 1 (EXT1), a central enzyme in HSPG biosynthesis, to be selectively upregulated in aggressive tumor subtypes and cancer cell lines, and to function as a key player in breast cancer aggressiveness. Notably, ectopic expression of EXT1 in epithelial cells is sufficient to induce HSPG levels and the expression of known mesenchymal markers, subsequently enhancing EMT features, including cell migration, invasion, and tumor formation. Additionally, EXT1 loss in MDA-MB-231 cells inhibits their aggressiveness-associated traits such as migration, chemoresistance, tumor formation, and metastasis. Our findings reveal that EXT1, through its role in HSPG biosynthesis, governs signal transducer and activator of transcription 3 (STAT3) signaling, a known regulator of cancer cell aggressiveness. Collectively, we present the EXT1/HSPG/STAT3 axis as a central regulator of cancer cell plasticity that directly links proteoglycan synthesis to oncogenic signaling pathways.

TPM3: a novel prognostic biomarker of cervical cancer that correlates with immune infiltration and promotes malignant behavior in vivo and in vitro

Cervical squamous cell carcinoma and endocervical adenocarcinoma (CESC) has become increasingly prevalent in younger women. Tropomyosin 3 (TPM3), a thin filament actin-binding protein, has been implicated in various malignancies. In this study, TPM3 expression was evaluated using RNA-seq data from The Cancer Genome Atlas (TCGA), and its relationship with CESC prognosis was examined with receiver operating characteristic (ROC) curves. The effects of TPM3 on cellular proliferation and migration were examined in CESC cell lines using Cell Counting Kit-8 (CCK-8), colony formation, and Transwell assays, while in vivo effects were assessed in mouse xenograft models. Furthermore, differentially expressed genes (DEGs) associated with TPM3 were investigated to determine their tumorigenic functions. Associations between TPM3, chemosensitivity, and immune infiltration were analyzed, as were links between mutations, methylation, and prognosis using the cBioPortal and MethSurv databases. Upregulation of TMP3 mRNA and protein levels was observed in CESC samples, with elevated mRNA levels associated with reduced overall survival. TPM3 showed an area under the curve (AUC) of 0.946 for CESC diagnosis and was found to regulate tumor proliferation and metastasis in vitro and in vivo. Overall, 3099 DEGs were identified and found to be enriched in key CESC progression-related signaling pathways. TPM3 expression was also correlated with intratumoral immune cell infiltration and immune checkpoint activity. Patients with higher TPM3 expression showed distinctive chemosensitivity profiles, and TPM3 gene methylation was linked to poorer CESC patient prognostic outcomes. In conclusion, TPM3 is a key regulator of CESC progression, prognosis, and the tumor immune microenvironment, suggesting its potential as a diagnostic or prognostic biomarker and target for CESC immunotherapy.