SMC3 epigenetic silencing regulates Rab27a expression and drives pancreatic cancer progression.

BACKGROUND: Pancreatic ductal adenocarcinoma (PDAC) is expected to soon surpass colorectal cancer as a leading cause of cancer mortality in both males and females in the US, only lagging behind lung cancer. The lethality of PDAC is driven by late diagnosis and inefficient therapies. The complex biology of PDAC involves various cellular components, including exosomes that carry molecular information between cells. Thus, recipient cells can be reprogrammed, impacting tumorigenesis. Rab27a is a GTPase responsible for the last step of exosomes biogenesis. Hence, dissecting the mechanisms that regulate the expression of Rab27a and that control exosomes biogenesis can provide fundamental insights into the molecular underpinnings regulating PDAC progression. METHODS: To assess the mechanism that regulates Rab27a expression in PDAC, we used PDAC cell lines. The biological significance of these findings was validated in PDAC genetically engineered mouse models (GEMMs) and human samples. RESULTS: In this work we demonstrate in human PDAC samples and GEMMs that Rab27a expression decreases throughout the development of the disease, and that Rab27a knockout promotes disease progression. What is more, we demonstrate that Rab27a expression is epigenetically regulated in PDAC. Treatment with demethylating agents increases Rab27a expression specifically in human PDAC cell lines. We found that SMC3, a component of the cohesin complex, regulates Rab27a expression in PDAC. SMC3 methylation is present in human PDAC specimens and treatment with demethylating agents increases SMC3 expression in human PDAC cell lines. Most importantly, high levels of SMC3 methylation are associated with a worse prognosis in PDAC. Mechanistically, we identified an enhancer region within the Rab27a gene that recruits SMC3, and modulates Rab27a expression. CONCLUSION: Overall, we dissected a mechanism that regulates Rab27a expression during PDAC progression and impacts disease prognosis.

Extracellular Vesicles from Pancreatic Cancer Stem Cells Lead an Intratumor Communication Network (EVNet) to fuel tumour progression.

OBJECTIVE: Intratumor heterogeneity drives cancer progression and therapy resistance. However, it has yet to be determined whether and how subpopulations of cancer cells interact and how this interaction affects the tumour. DESIGN: We have studied the spontaneous flow of extracellular vesicles (EVs) between subpopulations of cancer cells: cancer stem cells (CSC) and non-stem cancer cells (NSCC). To determine the biological significance of the most frequent communication route, we used pancreatic ductal adenocarcinoma (PDAC) orthotopic models, patient-derived xenografts (PDXs) and genetically engineered mouse models (GEMMs). RESULTS: We demonstrate that PDAC tumours establish an organised communication network between subpopulations of cancer cells using EVs called the EVNet). The EVNet is plastic and reshapes in response to its environment. Communication within the EVNet occurs preferentially from CSC to NSCC. Inhibition of this communication route by impairing Rab27a function in orthotopic xenographs, GEMMs and PDXs is sufficient to hamper tumour growth and phenocopies the inhibition of communication in the whole tumour. Mechanistically, we provide evidence that CSC EVs use agrin protein to promote Yes1 associated transcriptional regulator (YAP) activation via LDL receptor related protein 4 (LRP-4). Ex vivo treatment of PDXs with antiagrin significantly impairs proliferation and decreases the levels of activated YAP.Patients with high levels of agrin and low inactive YAP show worse disease-free survival. In addition, patients with a higher number of circulating agrin+ EVs show a significant increased risk of disease progression. CONCLUSION: PDAC tumours establish a cooperation network mediated by EVs that is led by CSC and agrin, which allows tumours to adapt and thrive. Targeting agrin could make targeted therapy possible for patients with PDAC and has a significant impact on CSC that feeds the tumour and is at the centre of therapy resistance.

Exosomes in cancer: Use them or target them?

Exosomes are small extracellular vesicles with a significant role in most processes associated with cancer. On one hand, exosomes role in the different hallmarks of cancer has been widely described, highlighting the urge to understand the potential to target communication mediated by exosomes as a novel therapeutic approach in cancer. On the other hand, exosomes stability in circulation and tumor-targeting capacity shows their applicability in the delivery of anti-cancer molecules. This review will discuss the dual applicability of exosomes in cancer focusing on their usage for therapy improvement, or their targeting to block their supportive role in tumor progression and response to therapy. We highlight the current developments and the strategies used to enhance the potential of exosomes to become clinical partners in the treatment of cancer.

Exosomes define a local and systemic communication network in healthy pancreas and pancreatic ductal adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC), a lethal disease, requires a grasp of its biology for effective therapies. Exosomes, implicated in cancer, are poorly understood in living systems. Here we use the genetically engineered mouse model (ExoBow) to map the spatiotemporal distribution of exosomes from healthy and PDAC pancreas in vivo to determine their biological significance. We show that, within the PDAC microenvironment, cancer cells establish preferential communication routes through exosomes with cancer associated fibroblasts and endothelial cells. The latter being a conserved event in the healthy pancreas. Inhibiting exosomes secretion in both scenarios enhances angiogenesis, underscoring their contribution to vascularization and to cancer. Inter-organ communication is significantly increased in PDAC with specific organs as most frequent targets of exosomes communication occurring in health with the thymus, bone-marrow, brain, and intestines, and in PDAC with the kidneys, lungs and thymus. In sum, we find that exosomes mediate an organized intra- and inter- pancreas communication network with modulatory effects in vivo.

Exosomes, microvesicles, and other extracellular vesicles-a Keystone Symposia report.

Extracellular vesicles (EVs) are small, lipid-bilayer-bound particles released by cells that can contain important bioactive molecules, including lipids, RNAs, and proteins. Once released in the extracellular environment, EVs can act as messengers locally as well as to distant tissues to coordinate tissue homeostasis and systemic responses. There is a growing interest in not only understanding the physiology of EVs as signaling particles but also leveraging them as minimally invasive diagnostic and prognostic biomarkers (e.g., they can be found in biofluids) and drug-delivery vehicles. On October 30-November 2, 2022, researchers in the EV field convened for the Keystone symposium "Exosomes, Microvesicles, and Other Extracellular Vesicles" to discuss developing standardized language and methodology, new data on the basic biology of EVs and potential clinical utility, as well as novel technologies to isolate and characterize EVs.

Quantitative Analysis of Precursors MicroRNAs and Their Respective Mature MicroRNAs in Cancer Exosomes Overtime.

Exosomes are a cell-to-cell communication system that transports information to neighbor and/or distant cells. Their content is composed of lipids, proteins, RNAs, and DNA. The role of exosomes released by cancer cells in disease progression has been widely studied. Here, we report a detailed protocol to quantify precursor microRNAs and mature microRNAs overtime in exosomes of cancer cells. Those precursor microRNAs that are packaged together with RISC proteins will get further processed in the exosomes overtime and an accumulation of the mature form of the microRNAs will occur.

Plasmatic miR-210, miR-221 and miR-1233 profile: potential liquid biopsies candidates for renal cell carcinoma.

Renal cell carcinoma (RCC) represents a challenge for clinicians since the nonexistence of screening and monitoring tests contributes to the fact that one-third of patients are diagnosed with metastatic disease and 20-40% of the remaining patients will also develop metastasis. Modern medicine is now trying to establish circulating biomolecules as the gold standard of biomarkers. Among the molecules that can be released from tumor cells we can find microRNAs. The aim of this study was to evaluate the applicability of cancer-related miR-210, miR-218, miR-221 and miR-1233 as prognostic biomarkers for RCC. Patients with higher levels of miR-210, miR-221 and miR-1233 presented a higher risk of specific death by RCC and a lower cancer-specific survival. The addition of miR-210, miR-221 and miR-1233 plasma levels information improved the capacity to predict death by cancer in 8, 4% when compared to the current variables used by clinicians. We also verified that hypoxia stimulates the release of miR-210 and miR-1233 from HKC-8, RCC-FG2 and 786-O cell lines. These results support the addition of circulating microRNAs as prognostic biomarkers for RCC.

miRNAs: mediators of ErbB family targeted therapy resistance.

The ErbB/HER tyrosine kinase receptors family plays a key regulatory role in different cellular processes by activating several signaling pathways. In different tumor types, mutations or overexpression of the ErbB family members are a common feature, which led to the development of targeted therapies against this receptors. Although with this kind of treatment we are heading to a more personalized medicine, the development of acquired resistance is still an issue, therefore, several studies focused on discovering the mechanisms behind it. More recently, miRNAs have been described as important mediators of acquired resistance, specifically, acquired resistance to ErbB family targeted therapies. Ultimately, miRNA-based therapeutics using exosomes as a drug delivery model can revolutionize today's approach of cancer treatment.