Stromal-induced mitochondrial re-education: Impact on epithelial-to-mesenchymal transition and cancer aggressiveness

Dynamics of Endothelial Cell Diversity and Plasticity in Health and Disease

Endothelial cells (ECs) are vital structural units of the cardiovascular system possessing two principal distinctive properties: heterogeneity and plasticity. Endothelial heterogeneity is defined by differences in tissue-specific endothelial phenotypes and their high predisposition to modification along the length of the vascular bed. This aspect of heterogeneity is closely associated with plasticity, the ability of ECs to adapt to environmental cues through the mobilization of genetic, molecular, and structural alterations. The specific endothelial cytoarchitectonics facilitate a quick structural cell reorganization and, furthermore, easy adaptation to the extrinsic and intrinsic environmental stimuli, known as the epigenetic landscape. ECs, as universally distributed and ubiquitous cells of the human body, play a role that extends far beyond their structural function in the cardiovascular system. They play a crucial role in terms of barrier function, cell-to-cell communication, and a myriad of physiological and pathologic processes. These include development, ontogenesis, disease initiation, and progression, as well as growth, regeneration, and repair. Despite substantial progress in the understanding of endothelial cell biology, the role of ECs in healthy conditions and pathologies remains a fascinating area of exploration. This review aims to summarize knowledge and concepts in endothelial biology. It focuses on the development and functional characteristics of endothelial cells in health and pathological conditions, with a particular emphasis on endothelial phenotypic and functional heterogeneity.

Ratiometric Inclusion of Fibroblasts Promotes Both Castration-Resistant and Androgen-Dependent Tumorigenic Progression in Engineered Prostate Cancer Tissues

To investigate the ratiometric role of fibroblasts in prostate cancer (PCa) progression, this work establishes a matrix-inclusive, 3D engineered prostate cancer tissue (EPCaT) model that enables direct coculture of neuroendocrine-variant castration-resistant (CPRC-ne) or androgen-dependent (ADPC) PCa cells with tumor-supporting stromal cell types. Results show that the inclusion of fibroblasts within CRPC-ne and ADPC EPCaTs drives PCa aggression through significant matrix remodeling and increased proliferative cell populations. Interestingly, this is observed to a much greater degree in EPCaTs formed with a small number of fibroblasts relative to the number of PCa cells. Fibroblast coculture also results in ADPC behavior more similar to the aggressive CRPC-ne condition, suggesting fibroblasts play a role in elevating PCa disease state and may contribute to the ADPC to CRPC-ne switch. Bulk transcriptomic analyses additionally elucidate fibroblast-driven enrichment of hallmark gene sets associated with tumorigenic progression. Finally, the EPCaT model clinical relevancy is probed through a comparison to the Cancer Genome Atlas (TCGA) PCa patient cohort; notably, similar gene set enrichment is observed between EPCaT models and the patient primary tumor transcriptome. Taken together, study results demonstrate the potential of the EPCaT model to serve as a PCa-mimetic tool in future therapeutic development efforts.

Skin precursor‐derived Schwann cells accelerate in vivo prevascularization of tissue‐engineered nerves to promote peripheral nerve regeneration

Prevascularization strategies have become a hot spot in tissue engineering. As one of the potential candidates for seed cells, skin precursor-derived Schwann cells (SKP-SCs) were endowed with a new role to more efficiently construct prevascularized tissue-engineered peripheral nerves. The silk fibroin scaffolds seeded with SKP-SCs were prevascularized through subcutaneously implantation, which was further assembled with the SKP-SC-containing chitosan conduit. SKP-SCs expressed pro-angiogenic factors in vitro and in vivo. SKP-SCs significantly accelerated the satisfied prevascularization in vivo of silk fibroin scaffolds compared with VEGF. Moreover, the NGF expression revealed that pregenerated blood vessels adapted to the nerve regeneration microenvironment through reeducation. The short-term nerve regeneration of SKP-SCs-prevascularization was obviously superior to that of non-prevascularization. At 12 weeks postinjury, both SKP-SCs-prevascularization and VEGF-prevascularization significantly improved nerve regeneration with a comparable degree. Our figures provide a new enlightenment for the optimization of prevascularization strategies and how to further utilize tissue engineering for better repair.

Unraveling the Peculiar Features of Mitochondrial Metabolism and Dynamics in Prostate Cancer

Prostate cancer (PCa) is the second leading cause of cancer deaths among men in Western countries. Mitochondria, the "powerhouse" of cells, undergo distinctive metabolic and structural dynamics in different types of cancer. PCa cells experience peculiar metabolic changes during their progression from normal epithelial cells to early-stage and, progressively, to late-stage cancer cells. Specifically, healthy cells display a truncated tricarboxylic acid (TCA) cycle and inefficient oxidative phosphorylation (OXPHOS) due to the high accumulation of zinc that impairs the activity of m-aconitase, the enzyme of the TCA cycle responsible for the oxidation of citrate. During the early phase of cancer development, intracellular zinc levels decrease leading to the reactivation of m-aconitase, TCA cycle and OXPHOS. PCa cells change their metabolic features again when progressing to the late stage of cancer. In particular, the Warburg effect was consistently shown to be the main metabolic feature of late-stage PCa cells. However, accumulating evidence sustains that both the TCA cycle and the OXPHOS pathway are still present and active in these cells. The androgen receptor axis as well as mutations in mitochondrial genes involved in metabolic rewiring were shown to play a key role in PCa cell metabolic reprogramming. Mitochondrial structural dynamics, such as biogenesis, fusion/fission and mitophagy, were also observed in PCa cells. In this review, we focus on the mitochondrial metabolic and structural dynamics occurring in PCa during tumor development and progression; their role as effective molecular targets for novel therapeutic strategies in PCa patients is also discussed.

The multifaceted roles of mitochondria at the crossroads of cell life and death in cancer

Mitochondria are the cytoplasmic organelles mostly known as the "electric engine" of the cells; however, they also play pivotal roles in different biological processes, such as cell growth/apoptosis, Ca²⁺ and redox homeostasis, and cell stemness. In cancer cells, mitochondria undergo peculiar functional and structural dynamics involved in the survival/death fate of the cell. Cancer cells use glycolysis to support macromolecular biosynthesis and energy production ("Warburg effect"); however, mitochondrial OXPHOS has been shown to be still active during carcinogenesis and even exacerbated in drug-resistant and stem cancer cells. This metabolic rewiring is associated with mutations in genes encoding mitochondrial metabolic enzymes ("oncometabolites"), alterations of ROS production and redox biology, and a fine-tuned balance between anti-/proapoptotic proteins. In cancer cells, mitochondria also experience dynamic alterations from the structural point of view undergoing coordinated cycles of biogenesis, fusion/fission and mitophagy, and physically communicating with the endoplasmic reticulum (ER), through the Ca²⁺ flux, at the MAM (mitochondria-associated membranes) levels. This review addresses the peculiar mitochondrial metabolic and structural dynamics occurring in cancer cells and their role in coordinating the balance between cell survival and death. The role of mitochondrial dynamics as effective biomarkers of tumor progression and promising targets for anticancer strategies is also discussed.

Inhibition of Migration, Invasion and Drug Resistance of Pancreatic Adenocarcinoma Cells - Role of Snail, Slug and Twist and Small Molecule Inhibitors

PURPOSE

The main purpose of this study is to demonstrate the effects of epithelial to mesenchymal transition activating transcription factor silencing (EMT-ATF silencing) on migration, invasion, drug resistance and tumor-forming abilities of various pancreatic cancer cell lines. Additionally, the contribution of small molecule inhibitors of EMT (SD-208 and CX4945) to the effects of gene silencing was evaluated.

METHODS

EMT activating transcription factors "Snail, Slug and Twist" were silenced by short hairpins on Panc-1, MIA PaCa-2, BxPC-3, and AsPC-1 pancreatic cancer cell lines. The changes in migration, invasion, laminin attachment, cancer stem-like cell properties and tumor-forming abilities were investigated. Chemosensitivity assays and small molecule inhibitors of EMT were applied to the metastatic pancreatic cancer cell line AsPC-1.

RESULTS

EMT-ATF silencing reduced EMT and stem cell-like characteristics of pancreatic cancer cell lines. Following EMT-ATF silencing amongst the four PC cell lines, AsPC-1 showed the best response and was chosen for further chemoresistance and combinational therapy applications. EMT downregulated AsPC-1 cells showed less resistance to select chemotherapeutics compared to the control group. Both small molecule inhibitors enhanced the outcomes of EMT-ATF silencing.

CONCLUSION

Overall it was found that EMT-ATF silencing, either by EMT-ATF silencing or with the enhancement by small molecules, is a good candidate to treat pancreatic cancer since it simultaneously minimizes metastasis, stem cell properties, and drug resistance.

Mitochondrial Redox Hubs as Promising Targets for Anticancer Therapy

Mitochondria play multifaceted roles in malignant tumor progression. Beyond their bioenergetic role, mitochondria are essential for providing malignant cells a higher plasticity to face the harsh environmental conditions. Cell-autonomous metabolic deregulation of cancer cells, or metabolic adaptation to microenvironmental cues (lack of nutrients, stromal supply, hypoxia, etc.), represent the triggering event of mitochondria overexploitation to orchestrate nutrient sensing and upload, signaling, and redox circuits. As readout of their higher function, mitochondria produce high amounts of reactive oxygen species (ROS) that are functional for multiple signaling networks underlying tumor proliferation, survival, and metastatic process. To compensate for the higher rate of mitochondrial ROS production, cancer cells have evolved adaptive mechanisms to increase their antioxidant systems and to address ROS activating pathways useful for the tumor cell adaptation to environmental changes. As these properties are critical for cancer progression, mitochondrial ROS have recently become an attractive target for anti-cancer therapies. We discuss how understanding of mitochondrial function in the tumor-specific generation of ROS will impact on the development of novel redox-based targeted therapeutic strategies.