Tumor Testing for Microsatellite Instability to Identify Lynch Syndrome: New Insights Into an Old Diagnostic Strategy

Lactate and lactylation in cancer

Accumulated evidence has implicated the diverse and substantial influence of lactate on cellular differentiation and fate regulation in physiological and pathological settings, particularly in intricate conditions such as cancer. Specifically, lactate has been demonstrated to be pivotal in molding the tumor microenvironment (TME) through its effects on different cell populations. Within tumor cells, lactate impacts cell signaling pathways, augments the lactate shuttle process, boosts resistance to oxidative stress, and contributes to lactylation. In various cellular populations, the interplay between lactate and immune cells governs processes such as cell differentiation, immune response, immune surveillance, and treatment effectiveness. Furthermore, communication between lactate and stromal/endothelial cells supports basal membrane (BM) remodeling, epithelial-mesenchymal transitions (EMT), metabolic reprogramming, angiogenesis, and drug resistance. Focusing on lactate production and transport, specifically through lactate dehydrogenase (LDH) and monocarboxylate transporters (MCT), has shown promise in the treatment of cancer. Inhibitors targeting LDH and MCT act as both tumor suppressors and enhancers of immunotherapy, leading to a synergistic therapeutic effect when combined with immunotherapy. The review underscores the importance of lactate in tumor progression and provides valuable perspectives on potential therapeutic approaches that target the vulnerability of lactate metabolism, highlighting the Heel of Achilles for cancer treatment.

Impact of population screening for Lynch syndrome insights from the All of Us data

Lynch Syndrome (LS) is a common genetic cancer condition that allows for personalized cancer prevention and early cancer detection in identified gene carriers. We used data from the All of Us (AOU) Research Initiative to assess the prevalence of LS in the general U.S. population, and analyzed demographic, personal, and family cancer history, stratified by LS genotype to compare LS and non-LS carriers. The results suggest that population-based germline testing for LS may identify up to 63.2% of carriers who might remain undetected due to lack of personal or family cancer history. LS affects about 1 in 354 individuals in this U.S. cohort, where pathogenic variants in the genes MSH6 and PMS2 account for the majority of cases. These results underscore the need to optimize the identification of LS across diverse populations and population-based germline testing may capture the most individuals who can benefit from precision cancer screening and prevention.

Microsatellite Instability: From the Implementation of the Detection to a Prognostic and Predictive Role in Cancers

Microsatellite instability (MSI) has been identified in several tumors arising from either germline or somatic aberration. The presence of MSI in cancer predicts the sensitivity to immune checkpoint inhibitors (ICIs), particularly PD1/PD-L1 inhibitors. To date, the predictive role of MSI is currently used in the selection of colorectal cancer patients for immunotherapy; moreover, the expansion of clinical trials into other cancer types may elucidate the predictive value of MSI for non-colorectal tumors. In clinical practice, several assays are used for MSI testing, including immunohistochemistry (IHC), polymerase chain reaction (PCR) and next-generation sequencing (NGS). In this review, we provide an overview of MSI in various cancer types, highlighting its potential predictive/prognostic role and the clinical trials performed. Finally, we focus on the comparison data between the different assays used to detect MSI in clinical practice.