Kras mutation correlating with circulating regulatory T cells predicts the prognosis of advanced pancreatic cancer patients

Purpose

Kras mutation and abnormal immune status are associated with pancreatic cancer development and progression. In this study, we evaluated the Kras mutation status in circulating tumor DNA and circulating T cell subsets in a cohort of advanced pancreatic cancer patients.

Methods

Samples were retrospectively obtained from a series of 210 pathological advanced pancreatic cancer patients between 2012 and 2014. The Kras mutation status was detected in cell‐free circulating tumor DNA (ctDNA) by ddPCR and circulating T cell subsets were analyzed by flow cytometry.

Results

Univariate analysis found that tumor node metastasis (TNM) stage, chemotherapy, circulating regulatory T cells, CA19‐9 levels, CA125 levels, and Kras^G12D and Kras^G12V mutations were significantly related to overall survival in advanced pancreatic cancer patients. Multivariate analysis identified that TNM stage (P = .03, HR:1.422), Tregs (P = .004, HR:1.522), CA19‐9 levels (P = .009, HR:1.488), Kras^G12D mutation (P = .044, HR:1.353), and Kras^G12V mutation (P = .001, HR:1.667) were independent prognostic markers. Furthermore, we found that Kras^G12V mutation in ctDNA was correlated with high circulating proportion of Tregs, and patients with both Kras^G12V mutation and high levels of Tregs were associated with extremely poor survival in advanced pancreatic cancer.

Conclusion

Kras^G12V mutation was associated with high circulating regulatory T cell levels, and both of them predicted worse prognosis in advanced pancreatic cancer patients.

Cell-free circulating epimarks in cancer monitoring

Cancer numbers increasing, cases heterogeneity and the drug resistance emergence have pushed scientists to search for innovative solutions for patients and epimutations can be one. Methylated DNA, modified nucleosomes and noncoding RNAs are found in all cells, including tumor cells. They are intracellular actors but also have intercellular communication roles, being released in extracellular environment and in different body fluids. Here, we reviewed current literature on the use of these blood circulating epimarks in cancer monitoring. What stands out is that epimarkers must be considered as ‘real time’ images of the tumor, and can be isolated without invasive methods. In the future, the real challenge lies in the development of specific, sensitive, fast and clinically applicable detection and analysis methods of epimarkers.

The pleiotropic role of proteoglycans in extracellular vesicle mediated communication in the tumor microenvironment

Compartmental exchange between cells through extracellular vesicles (EVs), including exosomes and microvesicles, has emerged as a central mechanism that coordinates the complex communication between malignant and stromal cells during tumor initiation and evolution. Some of the most critical processes of EV-mediated communication, including EV biogenesis and EV uptake, can be mediated by heparan sulfate proteoglycans (HSPGs) that reside on the surface of producer and recipient cells as well as on EVs. With interestingly similar, HSPG-dependent, pathways as the ones exploited by some viruses, EVs may, in an evolutionary perspective, be viewed as endogenous counterparts of viral particles. Cancer cell-derived EVs exert their protumorigenic effects by direct interactions of biologically active surface molecules, by transfer of proteins and nucleic acids into recipient cells or by transfer of metabolites that can be utilized as an energy source by the recipient cell. Here, we discuss the pleiotropic role of the HSPG family in these different contexts of EV communication with a specific focus on tumor development. We propose EV-associated PGs as dynamic reservoirs and chaperones of signaling molecules with potential implications in ligand exchange between EVs and tumor target cells. The protumorigenic consequences of EV mediated communication through HSPG should motivate the development of therapeutic approaches targeting EV-HSPG interactions as a novel strategy in cancer treatment.

The interplay of circulating tumor DNA and chromatin modification, therapeutic resistance, and metastasis

Peripheral circulating free DNA (cfDNA) is DNA that is detected in plasma or serum fluid with a cell-free status. For cancer patients, cfDNA not only originates from apoptotic cells but also from necrotic tumor cells and disseminated tumor cells that have escaped into the blood during epithelial-mesenchymal transition. Additionally, cfDNA derived from tumors, also known as circulating tumor DNA (ctDNA), carries tumor-associated genetic and epigenetic changes in cancer patients, which makes ctDNA a potential biomarker for the early diagnosis of tumors, monitory and therapeutic evaluations, and prognostic assessments, among others, for various kinds of cancer. Moreover, analyses of cfDNA chromatin modifications can reflect the heterogeneity of tumors and have potential for predicting tumor drug resistance.