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Breast Cancer Research : BCR Jun 2024The aberrant amplification of mammary luminal progenitors is at the origin of basal-like breast cancers associated with BRCA1 mutations. Integrins mediate cell-matrix...
BACKGROUND
The aberrant amplification of mammary luminal progenitors is at the origin of basal-like breast cancers associated with BRCA1 mutations. Integrins mediate cell-matrix adhesion and transmit mechanical and chemical signals that drive epithelial stem cell functions and regulate tumor progression, metastatic reactivation, and resistance to targeted therapies. Consistently, we have recently shown that laminin-binding integrins are essential for the expansion and differentiation of mammary luminal progenitors in physiological conditions. As over-expression of the laminin-binding α6 integrin (Itgα6) is associated with poor prognosis and reduced survival in breast cancer, we here investigate the role of Itgα6 in mammary tumorigenesis.
METHODS
We used Blg-Cre; Brca1; Trp53 mice, a model that phenocopies human basal-like breast cancer with BRCA1 mutations. We generated mutant mice proficient or deficient in Itgα6 expression and followed tumor formation. Mammary tumors and pretumoral tissues were characterized by immunohistochemistry, flow cytometry, RT-qPCR, Western blotting and organoid cultures. Clonogenicity of luminal progenitors from preneoplastic glands was studied in 3D Matrigel cultures.
RESULTS
We show that Itga6 deletion favors activation of p16 cell cycle inhibitor in the preneoplastic tissue. Subsequently, the amplification of luminal progenitors, the cell of origin of Brca1-deficient tumors, is restrained in Itgα6-deficient gland. In addition, the partial EMT program operating in Brca1/p53-deficient epithelium is attenuated in the absence of Itgα6. As a consequence of these events, mammary tumor formation is delayed in Itgα6-deficient mice. After tumor formation, the lack of Itgα6 does not affect tumor growth but rather alters their differentiation, resulting in reduced expression of basal cell markers.
CONCLUSIONS
Our data indicate that Itgα6 has a pro-tumorigenic role in Blg-Cre; Brca1; Trp53 mice developing basal-like mammary tumors. In particular, we reveal that Itgα6 is required for the luminal progenitor expansion and the aberrant partial EMT program that precedes the formation of BRCA1 deficient tumors.
Topics: Animals; Integrin alpha6; Female; Tumor Suppressor Protein p53; Mice; BRCA1 Protein; Breast Neoplasms; Humans; Neoplastic Stem Cells; Cell Proliferation; Stem Cells; Gene Deletion; Cell Transformation, Neoplastic
PubMed: 38835038
DOI: 10.1186/s13058-024-01851-4 -
Molecular Medicine (Cambridge, Mass.) Jun 2024Liver kinase B1 (LKB1) is frequently mutated in lung adenocarcinoma, and its loss contributes to tumor progression.
BACKGROUND
Liver kinase B1 (LKB1) is frequently mutated in lung adenocarcinoma, and its loss contributes to tumor progression.
METHODS
To identify LKB1 downstream genes that promote lung adenocarcinoma aggressiveness, we performed bioinformatical analysis using publicly available datasets.
RESULTS
Rab3B was upregulated in LKB1-depleted lung adenocarcinoma cells and suppressed by LKB1 overexpression. CREB protein was enriched at the promoter of Rab3B in lung cancer cells. Silencing of CREB abrogated the upregulation of Rab3B upon LKB1 loss. Immunohistochemistry revealed the elevated expression of Rab3B in lung adenocarcinomas relative to adjacent normal tissues. Upregulation of Rab3B was significantly associated with lymph node metastasis, advanced tumor stage, and reduced overall survival in lung adenocarcinoma patients. Knockdown of Rab3B suppressed and overexpression of Rab3B promoted the proliferation, colony formation, and migration of lung adenocarcinoma cells in vitro. In a mouse xenograft model, Rab3B depletion restrained and Rab3B overexpression augmented the growth of lung adenocarcinoma tumors. Mechanistically, Rab3B interacted with DDX6 and enhanced its protein stability. Ectopic expression of DDX6 significantly promoted the proliferation, colony formation, and migration of lung adenocarcinoma cells. DDX6 knockdown phenocopied the effects of Rab3B depletion on lung adenocarcinoma cells. Additionally, DDX6 overexpression partially rescued the aggressive phenotype of Rab3B-depleted lung adenocarcinoma cells.
CONCLUSION
LKB1 deficiency promotes Rab3B upregulation via a CREB-dependent manner. Rab3B interacts with and stabilizes DDX6 protein to accelerate lung adenocarcinoma progression. The Rab3B-DDX6 axis may be potential therapeutic target for lung adenocarcinoma.
Topics: Animals; Female; Humans; Male; Mice; Adenocarcinoma of Lung; AMP-Activated Protein Kinase Kinases; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cyclic AMP Response Element-Binding Protein; DEAD-box RNA Helicases; Gene Expression Regulation, Neoplastic; Lung Neoplasms; Protein Serine-Threonine Kinases; Protein Stability
PubMed: 38834947
DOI: 10.1186/s10020-024-00848-1 -
Matrix Biology Plus Jun 2024Although the mechanism for activation of latent TGFβ1 and TGFβ3 is understood to involve the binding of the TGFβ propeptide (LAP) to both an integrin and an insoluble...
Although the mechanism for activation of latent TGFβ1 and TGFβ3 is understood to involve the binding of the TGFβ propeptide (LAP) to both an integrin and an insoluble substrate, the activation of latent TGFβ2 has been unclear because the TGFβ2 LAP does not have the classical integrin binding sequence found in the other two TGFβ isoform LAPs. To assess the potential requirement for covalent linkage with a matrix or cell surface protein for the activation of latent TGFβ2, we generated mice in which the TGFβ2 Cys residue predicted to be involved in binding was mutated to Ser (). We reasoned that, if covalent interaction with a second molecule is required for latent TGFβ2 activation, mutant mice should display a null ()-like phenotype. mice closely phenocopy mice with death in utero between E18 and P1 and with congenital heart and kidney defects similar to those described for mice. The mutant latent TGFβ2 is secreted at levels similar to WT, yet TGFβ signaling monitored as nuclear pSmad2 is suppressed. We conclude that, like latent TGFβ1, latent TGFβ2 activation requires binding to an immobilized matrix or plasma membrane molecule.
PubMed: 38831847
DOI: 10.1016/j.mbplus.2024.100149 -
Cell Reports May 2024Atoh7 is transiently expressed in retinal progenitor cells (RPCs) and is required for retinal ganglion cell (RGC) differentiation. In humans, a deletion in a distal...
Atoh7 is transiently expressed in retinal progenitor cells (RPCs) and is required for retinal ganglion cell (RGC) differentiation. In humans, a deletion in a distal non-coding regulatory region upstream of ATOH7 is associated with optic nerve atrophy and blindness. Here, we functionally interrogate the significance of the Atoh7 regulatory landscape to retinogenesis in mice. Deletion of the Atoh7 enhancer structure leads to RGC deficiency, optic nerve hypoplasia, and retinal blood vascular abnormalities, phenocopying inactivation of Atoh7. Further, loss of the Atoh7 remote enhancer impacts ipsilaterally projecting RGCs and disrupts proper axonal projections to the visual thalamus. Deletion of the Atoh7 remote enhancer is also associated with the dysregulation of axonogenesis genes, including the derepression of the axon repulsive cue Robo3. Our data provide insights into how Atoh7 enhancer elements function to promote RGC development and optic nerve formation and highlight a key role of Atoh7 in the transcriptional control of axon guidance molecules.
PubMed: 38823017
DOI: 10.1016/j.celrep.2024.114291 -
IScience Jun 2024Cancer-mesothelial cell interactions are critical for multiple solid tumors to colonize the surface of peritoneal organs. Understanding mechanisms of mesothelial barrier...
Cancer-mesothelial cell interactions are critical for multiple solid tumors to colonize the surface of peritoneal organs. Understanding mechanisms of mesothelial barrier dysfunction that impair its protective function is critical for discovering mesothelial-targeted therapies to combat metastatic spread. Here, we utilized a live cell imaging-based assay to elucidate the dynamics of ovarian cancer spheroid transmesothelial migration and mesothelial-generated mechanical forces. Treatment of mesothelial cells with the adenylyl cyclase agonist forskolin strengthens cell-cell junctions, reduces actomyosin fibers, contractility-driven matrix displacements, and cancer spheroid transmigration in a protein kinase A (PKA)-dependent mechanism. We also show that inhibition of the cytoskeletal regulator Rho-associated kinase in mesothelial cells phenocopies the anti-metastatic effects of forskolin. Conversely, upregulation of contractility in mesothelial cells disrupts cell-cell junctions and increases the clearance rates of ovarian cancer spheroids. Our findings demonstrate the critical role of mesothelial cell contractility and mesothelial barrier integrity in regulating metastatic dissemination within the peritoneal microenvironment.
PubMed: 38812549
DOI: 10.1016/j.isci.2024.109950 -
Frontiers in Genetics 2024Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease caused by a combination of genetic and environmental factors. Rare variants with low predicted...
Rheumatoid arthritis (RA) is a chronic, systemic autoimmune disease caused by a combination of genetic and environmental factors. Rare variants with low predicted effects in genes participating in the same biological function might be involved in developing complex diseases such as RA. From whole-exome sequencing (WES) data, we identified genes containing rare non-neutral variants with complete penetrance and no phenocopy in at least one of nine French multiplex families. Further enrichment analysis highlighted focal adhesion as the most significant pathway. We then tested if interactions between the genes participating in this function would increase or decrease the risk of developing RA disease. The model-based multifactor dimensionality reduction (MB-MDR) approach was used to detect epistasis in a discovery sample (19 RA cases and 11 healthy individuals from 9 families and 98 unrelated CEU controls from the International Genome Sample Resource). We identified 9 significant interactions involving 11 genes (, , , , , , , , , , and ). One interaction (* increasing RA risk and one interaction decreasing (*) were confirmed in a replication sample (200 unrelated RA cases and 91 GBR unrelated controls). Functional and genomic data in RA samples or relevant cell types argue the key role of these genes in RA.
PubMed: 38803542
DOI: 10.3389/fgene.2024.1375036 -
Nucleic Acids Research Jun 2024TIMELESS (TIM) in the fork protection complex acts as a scaffold of the replisome to prevent its uncoupling and ensure efficient DNA replication fork progression....
TIMELESS (TIM) in the fork protection complex acts as a scaffold of the replisome to prevent its uncoupling and ensure efficient DNA replication fork progression. Nevertheless, its underlying basis for coordinating leading and lagging strand synthesis to limit single-stranded DNA (ssDNA) exposure remains elusive. Here, we demonstrate that acute degradation of TIM at ongoing DNA replication forks induces the accumulation of ssDNA gaps stemming from defective Okazaki fragment (OF) processing. Cells devoid of TIM fail to support the poly(ADP-ribosyl)ation necessary for backing up the canonical OF processing mechanism mediated by LIG1 and FEN1. Consequently, recruitment of XRCC1, a known effector of PARP1-dependent single-strand break repair, to post-replicative ssDNA gaps behind replication forks is impaired. Physical disruption of the TIM-PARP1 complex phenocopies the rapid loss of TIM, indicating that the TIM-PARP1 interaction is critical for the activation of this compensatory pathway. Accordingly, combined deficiency of FEN1 and the TIM-PARP1 interaction leads to synergistic DNA damage and cytotoxicity. We propose that TIM is essential for the engagement of PARP1 to the replisome to coordinate lagging strand synthesis with replication fork progression. Our study identifies TIM as a synthetic lethal target of OF processing enzymes that can be exploited for cancer therapy.
Topics: Humans; Cell Cycle Proteins; DNA; DNA Ligase ATP; DNA Repair; DNA Replication; DNA, Single-Stranded; DNA-Binding Proteins; Flap Endonucleases; Intracellular Signaling Peptides and Proteins; Poly (ADP-Ribose) Polymerase-1; X-ray Repair Cross Complementing Protein 1
PubMed: 38801073
DOI: 10.1093/nar/gkae445 -
BioRxiv : the Preprint Server For... May 2024Understanding pancreatic cancer biology is fundamental for identifying new targets and for developing more effective therapies. In particular, the contribution of the...
UNLABELLED
Understanding pancreatic cancer biology is fundamental for identifying new targets and for developing more effective therapies. In particular, the contribution of the stromal microenvironment to pancreatic cancer tumorigenesis requires further exploration. Here, we report the stromal roles of the synaptic protein Netrin G1 Ligand (NGL-1) in pancreatic cancer, uncovering its pro-tumor functions in cancer-associated fibroblasts and in immune cells. We observed that the stromal expression of NGL-1 inversely correlated with patients' overall survival. Moreover, germline knockout (KO) mice for NGL-1 presented decreased tumor burden, with a microenvironment that is less supportive of tumor growth. Of note, tumors from NGL-1 KO mice produced less immunosuppressive cytokines and displayed an increased percentage of CD8 T cells than those from control mice, while preserving the physical structure of the tumor microenvironment. These effects were shown to be mediated by NGL-1 in both immune cells and in the local stroma, in a TGF-β-dependent manner. While myeloid cells lacking NGL-1 decreased the production of immunosuppressive cytokines, NGL-1 KO T cells showed increased proliferation rates and overall polyfunctionality compared to control T cells. CAFs lacking NGL-1 were less immunosuppressive than controls, with overall decreased production of pro-tumor cytokines and compromised ability to inhibit CD8 T cells activation. Mechanistically, these CAFs downregulated components of the TGF-β pathway, AP-1 and NFAT transcription factor families, resulting in a less tumor-supportive phenotype. Finally, targeting NGL-1 genetically or using a functionally antagonistic small peptide phenocopied the effects of chemotherapy, while modulating the immunosuppressive tumor microenvironment (TME), rather than eliminating it. We propose NGL-1 as a new local stroma and immunomodulatory molecule, with pro-tumor roles in pancreatic cancer.
STATEMENT OF SIGNIFICANCE
Here we uncovered the pro-tumor roles of the synaptic protein NGL-1 in the tumor microenvironment of pancreatic cancer, defining a new target that simultaneously modulates tumor cell, fibroblast, and immune cell functions. This study reports a new pathway where NGL-1 controls TGF-β, AP-1 transcription factor members and NFAT1, modulating the immunosuppressive microenvironment in pancreatic cancer. Our findings highlight NGL-1 as a new stromal immunomodulator in pancreatic cancer.
PubMed: 38798370
DOI: 10.1101/2024.05.15.594354 -
Kidney International May 2024ZFYVE21 is an ancient, endosome-associated protein that is highly expressed in endothelial cells (ECs) but whose function(s) in vivo are undefined. Here, we identified...
ZFYVE21 is an ancient, endosome-associated protein that is highly expressed in endothelial cells (ECs) but whose function(s) in vivo are undefined. Here, we identified ZFYVE21 as an essential regulator of vascular barrier function in the aging kidney. ZFYVE21 levels significantly decline in ECs in aged human and mouse kidneys. To investigate attendant effects, we generated EC-specific Zfyve21 reporter mice. These knockout mice developed accelerated aging phenotypes including reduced endothelial nitric oxide (ENOS) activity, failure to thrive, and kidney insufficiency. Kidneys from Zfyve21 EC mice showed interstitial edema and glomerular EC injury. ZFYVE21-mediated phenotypes were not programmed developmentally as loss of ZFYVE21 in ECs during adulthood phenocopied its loss prenatally, and a nitric oxide donor normalized kidney function in adult hosts. Using live cell imaging and human kidney organ cultures, we found that in a GTPase Rab5- and protein kinase Akt-dependent manner, ZFYVE21 reduced vesicular levels of inhibitory caveolin-1 and promoted transfer of Golgi-derived ENOS to a perinuclear Rab5 vesicular population to functionally sustain ENOS activity. Thus, our work defines a ZFYVE21- mediated trafficking mechanism sustaining ENOS activity and demonstrates the relevance of this pathway for maintaining kidney function with aging.
PubMed: 38797325
DOI: 10.1016/j.kint.2024.05.007 -
Redox Biology Jul 2024Accumulating oxidative damage is a primary driver of ovarian reserve decline along with aging. However, the mechanism behind the imbalance in reactive oxygen species...
Accumulating oxidative damage is a primary driver of ovarian reserve decline along with aging. However, the mechanism behind the imbalance in reactive oxygen species (ROS) is not yet fully understood. Here we investigated changes in iron metabolism and its relationship with ROS disorder in aging ovaries of mice. We found increased iron content in aging ovaries and oocytes, along with abnormal expression of iron metabolic proteins, including heme oxygenase 1 (HO-1), ferritin heavy chain (FTH), ferritin light chain (FTL), mitochondrial ferritin (FTMT), divalent metal transporter 1 (DMT1), ferroportin1(FPN1), iron regulatory proteins (IRP1 and IRP2) and transferrin receptor 1 (TFR1). Notably, aging oocytes exhibited enhanced ferritinophagy and mitophagy, and consistently, there was an increase in cytosolic Fe2+, elevated lipid peroxidation, mitochondrial dysfunction, and augmented lysosome activity. Additionally, the ovarian expression of p53, p21, p16 and microtubule-associated protein tau (Tau) were also found to be upregulated. These alterations could be phenocopied with in vitro Fe2+ administration in oocytes from 2-month-old mice but were alleviated by deferoxamine (DFO). In vivo application of DFO improved ovarian iron metabolism and redox status in 12-month-old mice, and corrected the alterations in cytosolic Fe, ferritinophagy and mitophagy, as well as related degenerative changes in oocytes. Thereby in the whole, DFO delayed the decline in ovarian reserve and significantly increased the number of superovulated oocytes with reduced fragmentation and aneuploidy. Together, our findings suggest that aging-related disturbance in ovarian iron homeostasis contributes to excessive ROS production and that iron chelation may improve ovarian redox status, and efficiently delay the decline in ovarian reserve and oocyte quality in aging mice. These data propose a novel intervention strategy for preserving the ovarian reserve function in elderly women.
Topics: Animals; Oocytes; Mice; Female; Iron; Aging; Ovary; Oxidation-Reduction; Reactive Oxygen Species; Mitochondria; Oxidative Stress; Mitophagy; Lipid Peroxidation; Cellular Microenvironment; Ovarian Reserve
PubMed: 38781731
DOI: 10.1016/j.redox.2024.103195