Andrew B. Gladden

The Combined Effects of Urine Zinc, Cadmium, Mercury, Lead, and Copper on Endometrial Cancer Staging

Endometrial cancer (EC) is a growing public health concern. This secondary data study of a case series leveraged existing samples and data to explore the potential link between exposure to heavy metals/essential elements and stage of EC. We analyzed urine samples from women with EC, measuring levels of toxic metals (cadmium, mercury, and lead) and essential elements (zinc and copper). Our findings revealed that higher levels of mercury, cadmium, and lead are associated with more advanced EC stages. Conversely, zinc showed a protective effect, potentially mitigating EC stage progression. Copper levels did not show a clear association with EC stage. These results highlight the potential impact of environmental exposures on EC stage and the crucial need for advanced statistical methods to understand the combined effects of these pollutants on health and the need for public health interventions. Further research is needed to explore the mechanisms by which these metals influence EC stage and long-term outcomes.

Loss of Ribosomal Protein L22 (RPL22) Expression Identifies a Transcriptional Subset of MLH1-Deficient Endometrial Cancers With Lower Numbers of Tumor-Associated Lymphocytes

Microsatellite instability-high defines one of the major subsets of endometrial cancer (EC), characterized by defects in DNA mismatch repair, most often by loss of MLH1 protein expression, and sensitivity to immunotherapies. RPL22 is selectively mutated in microsatellite instability-high cancers, resulting in loss of protein expression. The significance of this mutation is unknown. An immunohistochemistry assay was developed that reliably detected ECs with ribosomal protein L22 (RPL22) protein loss. With a cohort of ECs, we identified MLH1-deficient cancers with loss of RPL22 expression. Using digital spatial transcriptomics, a subset was identified that was characterized by no expression of RPL22, lower expression of β-2 microglobulin, lack of expression of immune activation pathways, and lower numbers of tumor-associated CD8+ lymphocytes. β-2 Microglobulin, which is necessary for antigen presentation to T lymphocytes, was decreased in EC cell lines with RPL22 knocked down. Neither RPL22 expression nor levels of tumor-associated T lymphocytes were associated with tumor mutation burden or PD-L1 expression, 2 biomarkers that are assessed in patients considered for immunotherapies. This study provides the first evidence that RPL22 deficiency is an easily measured indicator of a unique subset of MLH1-deficient ECs that can be characterized as immune low. Our study suggests that patients with RPL22-deficient tumors could represent poor candidates for CD8+ T-cell-based immunotherapies, a current frontline therapy for MLH1-deficient ECs.

Differential Localization of β-Catenin Protein in CTNNB1 Mutant Endometrial Cancers Results in Distinct Transcriptional Profiles

CTNNB1 exon 3 mutation is a well-established driver of nearly 30% of endometrioid endometrial cancers (EECs), and this is associated with worse patient survival. Paradoxically, we have previously demonstrated that mutant β-catenin protein does not robustly localize to the nucleus in these cancers. The purpose of this study was to determine downstream gene expression in these cancers with nuclear or membrane/cytoplasmic mutant β-catenin protein localization. Spatial transcriptomics was performed on tumors with intratumor nuclear and nonnuclear mutant β-catenin, using the protein localization to select for regions of interest (ROIs). Differential expression analysis of all nuclear and nonnuclear ROIs yielded distinct transcriptional profiles based on the localization of β-catenin. Analysis revealed enrichment for Wnt signaling and epithelial-to-mesenchymal transition pathways in nuclear ROIs and hormone signaling in nonnuclear ROIs. Hierarchical clustering yielded 2 clusters comprised of almost entirely nuclear or nonnuclear ROIs. A novel therapeutic target, TROP2, encoded by the TACSTD2 gene, was identified to be altered by Wnt/β-catenin signaling. These data provide evidence for highly heterogeneous intratumor transcriptional profiles dependent on β-catenin protein localization in EEC with CTNNB1 driver mutations. Therefore, reporting of β-catenin immunohistochemistry should include an estimated percentage of tumor with nuclear localization in EEC tumors with exon 3 CTNNB1 mutations.

ARID1A: gene, protein, and function in endometrial cancer

ARID1A, a key structural subunit of the SWI/SNF chromatin remodeling complex, is the most frequently mutated SWI/SNF subunit in cancer with most mutations occurring in endometrial cancer. In a multitude of malignancies, loss of ARID1A protein correlates with poor patient prognosis, increased metastasis, and changes to key cancer pathways such as genomic instability. Despite this, little work has been done to deduce the molecular role of ARID1A in endometrial cancer progression and prognosis, and much of the present work is conflicting data. There is a growing body of work that shows a discordance between ARID1A mutation status and expression of ARID1A protein in endometrioid-type endometrial tumors. Several other malignancies have found that alternative mechanisms of ARID1A protein regulation can confer ARID1A protein loss. Therefore, relying solely on ARID1A sequencing may overlook a cohort of endometrial cancer patients with absence of ARID1A protein. With endometrial cancer being one of the sole malignancies increasing in both incidence and patient mortality since the mid-2000s, it is of upmost importance to assess the impacts and potential prognostic use of commonly mutated proteins such as ARID1A. This review will highlight the critical role of ARID1A in endometrial cancer pathogenesis, its potential therapeutic vulnerabilities, and emphasizes the need to move beyond ARID1A mutation as a sole diagnostic marker to elucidate its molecular and clinical implications in endometrial cancer.