Role of myoferlin in mitochondrial dynamics and metabolic fitness of Pancreatic Ductal Adenocarcinoma

Pancreatic cancer is the 7th most common cause of cancer mortality in the world. It is predicted to become the 2nd leading cause of cancer-related death in 2030. In the majority of cases, due to a late diagnosis, the tumor is not resectable and already disseminated. Therefore, new specific biomarkers providing early diagnosis for pancreatic cancer are needed. In addition to the lack of specific and early biomarkers, chemotherapies (gemcitabine and folfirinox) poorly improve the overall survival of Pancreatic Ductal Adenocarcinoma (PDAC) patients. Hence, a better understanding of physiopathological processes underlying PDAC is required in order to offer more effective treatments. Myoferlin is a 230 kDa protein with multiple C2 domains known to interact, through calcium binding, with negatively charged phospholipids. This protein was first described in myoblast fusion. Interestingly, Myoferlin is also overexpressed in several cancers, including pancreatic cancer, where it plays a role in endocytosis, exocytosis, and has been located in exosomes. Recently, our team showed a fragmentation of the mitochondrial network in PDAC cells when myoferlin was depleted using siRNA. Understanding the mechanism underlying this mitochondrial disruption would be of great interest as mitochondria are major actors in cancer development, progression and resistance. Owing to the known role of myoferlin in membrane fusion, we assessed its direct involvement in the mitochondrial fusion machinery. Indeed, if myoferlin is a part of the mitochondrial fusion machinery, its silencing together with an unopposed fission would lead to mitochondrial fragmentation. First, we performed immunofluorescence to colocalize myoferlin and a mitochondrial outer membrane 65kDa protein. Colocalization studies showed no significant colocalization. We then performed immunofluorescence to stained myoferlin and the main factor of mitochondrial fusion mitofusin-1/2 (MFN1/2). Colocalization image analysis revealed a 60% colocalization between both proteins. Those results were further confirmed by PLA (Proximity Ligation Assay). Finally, to evaluate a direct protein-protein interaction, we performed a co-immunoprecipitation assay. The main isoform of myoferlin appeared to coimmunoprecipitate with MFN1/2, suggesting a direct interaction between these proteins.Role of myoferlin in mitochondrial dynamics and metabolic fitness of pancreatic cance

One-stage versus two-stage piezocision-assisted orthodontic tooth movement: A preclinical study based on Nano-CT and RT-PCR analyses.

peer reviewed[en] OBJECTIVE: To evaluate the effect of a second-stage piezocision on the biological response. MATERIALS AND METHODS: 60 rats were randomly allocated to 6 experimental groups of 10 rats. Rats undergoing a one-stage piezocision were sacrified on day 7, 28 and 42 (groups 1-3) while rats undergoing a two-satge piezocision were sacrified on day 42, 63 and 90 (groups 4-6), respectively. The biological response was investigated in 3D at the tissue level using Nano-computed tomography (Nano-CT) and, at the molecular level using the qRT-PCR technique. Bone Volume Fraction (BVF) loss was the primary endpoint. RESULTS: Similar loss of BVF were observed both after the first and second piezocisions. The change in BVF loss between 7 and 28 days after each piezocision were 25.1 ± 13.0 (SE)% and 11.2 ± 11.6 (SE)% respectively and did not differ from each other (p = 0.43). Changes in BVF loss from 7 to 42 days were also comparable in one-stage and two-stage piezocision (4.9 ± 12.3 (SE) vs. -19.9 ± 13.4 (SE), p = 0.19). At the molecular level, all parameters except Translating Ribosome Affinity Purification (TRAP) protein had identical patterns. CONCLUSION: Within the limits of the present study, a second piezocision allowed to re-induce the Regional Acceleratory Phenomenon (RAP) effect. Nevertheless, the relevance of the findings to the clinical effect has not been tested

Le ciblage de la myoferline induit la mitophagie et amorce la ferroptose dans les cellules cancéreuses pancréatiques

peer reviewe

Myoferlin contributes to the metastatic phenotype of pancreatic cancer cells by enhancing their migratory capacity through the control of oxidative phosphorylation

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies with an overall survival of 5%, and is the second cause of death by cancer, mainly linked to its high metastatic aggressiveness. Accordingly, understanding the mechanisms sustaining the PDAC metastatic phenotype remains a priority. In this study, we have generated and used a murine in vivo model to select clones from the human PANC-1 PDAC cell line that exhibit a high propensity to seed and metastasized into the liver. We showed that myoferlin, a protein previously reported to be overexpressed in PDAC, is significantly involved in the migratory abilities of the selected cells. We first report that highly PANC-1 metastatic clones expressed significantly higher myoferlin level than the corresponding low metastatic ones. Using scratch wound and Boyden’s chamber assays, we show that cells expressing high myoferlin level have higher migratory potential than cells characterized by a low myoferlin abundance. Moreover, we demonstrate that myoferlin silencing leads to a migration decrease associated to a reduction of mitochondrial respiration. Since mitochondrial oxidative phosphorylation has been shown to be implicated in the tumor progression and dissemination, our data identify myoferlin as a valid potential therapeutic target in PDAC

Myoferlin targeting triggers mitophagy and primes ferroptosis in pancreatic cancer cells

Myoferlin, an emerging oncoprotein, has been associated with a low survival in several cancer types including pancreas ductal adenocarcinoma where it controls mitochondria structure and respiratory functions. Owing to the high susceptibility of KRAS-mutated cancer cells to iron-dependent cell death, ferroptosis, and to the high iron content in mitochondria, we investigated the relation existing between mitochondrial integrity and iron-dependent cell death. We discovered that myoferlin targeting with WJ460 pharmacological compound triggered mitophagy and ROS accumulation culminating with lipid peroxidation and apoptosis-independent cell death. WJ460 caused a reduction of the abundance of ferroptosis core regulators xc- cystine/glutamate transporter and GPX-4. Mitophagy inhibitor Mdivi1 and iron chelators inhibited the myoferlin-related ROS production and restored cell growth. Additionally, we reported a synergic effect between ferroptosis inducers, erastin and RSL3, and WJ460

Identification of myoferlin as a component of mitochondria-associated membranes and discovery of a new function in calcium transfer in PDAC cell lines

Pancreatic cancer is one of the deadliest cancers, with a five-year survival rate being less than 9%. This low survival rate is explained by the late diagnosis and the inefficient treatments. Therefore, developing new therapeutic strategies is needed to improve the survival of patients with pancreatic cancer. In this context, targeting cancer cell metabolism has been proposed as a promising approach, since cancer cells adapt their metabolism to face challenging environmental conditions and to fit their needs for proliferation. Many proteins have been proposed as therapeutic targets, where their targeting enables to create a metabolic imbalance, sensitizing cancer cells to other therapeutics treatments. One of these proteins, named myoferlin, is overexpressed in pancreatic cancer, where it influences cell metabolism. Indeed, myoferlin silencing in pancreatic cancer cells impairs lysosomes integrity, endosomal trafficking and also decreases mitochondrial respiration, which is associated with a fragmented network. Since mitochondria have been reported as key actors for proliferation, relapse and resistance to chemotherapy, we aimed at investigating the role of myoferlin in mitochondrial metabolism and dynamics. We first hypothesized that myoferlin was directly involved in mitochondrial dynamics and metabolism by being present on this organelle and by interacting with proteins involved in mitochondrial dynamics. Interestingly, we found that myoferlin is interacting with MFNs, proteins involved in mitochondrial fusion. However, our results suggested that myoferlin is unlikely located on mitochondria but is rather located in the membranes associated with this organelle. Due to its peculiar structure and reported function in the cell, we investigated a potential function for myoferlin in calcium transfer between endoplasmic reticulum and mitochondria. Our results showed that myoferlin silencing significantly reduces the mitochondrial calcium level upon stimulation, probably through its interaction with IP3R3. This discovery improves our comprehension of myoferlin function in cancer biology and could be extended to other myoferlin functions in a non-cancer context.Role of myoferlin in mitochondrial dynamics and metabolic fitness of pancreas cance