Angio-Associated Migratory Cell Protein (AAMP) Regulates the Hippo/YAP Pathway and Mitochondrial Functionality to Drive Osteosarcoma Metastasis

Background: Osteosarcoma (OS) is the prevalent form of primary bone cancer among adolescents, but the 5-year overall survival rate for patients with a metastatic or recurrent OS is under 20%. Angio-associated migratory cell protein (AAMP) is known to be a key regulator of cellular migration, yet its role in the context of OS metastasis has yet to be firmly established.Methods: Bioinformatics analyses were used to explore the association between AAMP and YAP expression and the prognosis of OS patients, and to evaluate differences in AAMP expression in patients with primary OS, recurrent OS, and pulmonary metastatic OS. Immunohistochemical (IHC) staining was additionally performed to compare AAMP levels in primary OS and pulmonary metastatic OS patient samples. Lentiviral transduction was further used to establish OS cell lines in which AAMP or YAP had been stably knocked down or overexpressed. OS cell migration and invasion were assessed using wound healing and Transwell assays. Proteins associated with the mitochondria, the epithelial-mesenchymal transition (EMT), YAP, and its target proteins were assessed in OS cell lines via Western blotting. OS cell lamellipodia were detected via phalloidin staining. Mitochondrial morphological characteristics were assessed via transmission electron microscopy following the knockdown of AAMP. An ATP kit was employed to measure ATP levels in OS cells in which AAMP had been knocked down. Animal model studies were used to confirm indices associated with OS cell lung metastasis following AAMP knockdown. Results: Patients with metastatic OS exhibit higher levels of AAMP expression that are correlated with poorer patient prognosis. Knocking down AAMP suppressed the migratory, invasive, and EMT activity of analyzed OS cell lines. AAMP was found to regulate CFL1 and thereby control OS cell protrusion. AAMP knockdown was further found to promote OS cell mitochondrial dysfunction and decreased intracellular ATP production, with these AAMP knockdown cells exhibiting impaired migratory and invasive activity as a consequence of YAP inhibition. Consistently, the knockdown of AAMP suppressed the in vivo metastasis of OS cells. Conclusions: Together, these data highlight a model wherein AAMP can promote OS cell migratory and invasive activity by regulating YAP and mitochondrial functionality. The AAMP/CFL1/YAP signaling pathway may thus represent a viable therapeutic target for efforts aimed at suppressing the metastatic progression of OS.

From Microspikes to Stress Fibers: Actin Remodeling in Breast Acini Drives Myosin II-Mediated Basement Membrane Invasion

The cellular mechanisms of basement membrane (BM) invasion remain poorly understood. We investigated the invasion-promoting mechanisms of actin cytoskeleton reorganization in BM-covered MCF10A breast acini. High-resolution confocal microscopy has characterized actin cell protrusion formation and function in response to tumor-resembling ECM stiffness and soluble EGF stimulation. Traction force microscopy quantified the mechanical BM stresses that invasion-triggered acini exerted on the BM–ECM interface. We demonstrate that acini use non-proteolytic actin microspikes as functional precursors of elongated protrusions to initiate BM penetration and ECM probing. Further, these microspikes mechanically widened the collagen IV pores to anchor within the BM scaffold via force-transmitting focal adhesions. Pre-invasive basal cells located at the BM–ECM interface exhibited predominantly cortical actin networks and actin microspikes. In response to pro-invasive conditions, these microspikes accumulated and converted subsequently into highly contractile stress fibers. The phenotypical switch to stress fiber cells matched spatiotemporally with emerging high BM stresses that were driven by actomyosin II contractility. The activation of proteolytic invadopodia with MT1-MMP occurred at later BM invasion stages and only in cells already disseminating into the ECM. Our study demonstrates that BM pore-widening filopodia bridge mechanical ECM probing function and contractility-driven BM weakening. Finally, these EMT-related cytoskeletal adaptations are critical mechanisms inducing the invasive transition of benign breast acini.

Hhex inhibits cell migration via regulating RHOA/CDC42-CFL1 axis in human lung cancer cells

Background Hhex(human hematopoietically expressed homeobox), also known as PRH, is originally considered as a transcription factor to regulate gene expression due to its homebox domain. Increasing studies show that Hhex plays a significant role in development, including anterior–posterior axis formation, vascular development and HSCs self-renewal etc. Hhex is linked to many diseases such as cancers, leukemia, and type-2 diabetes. Although Hhex is reported to inhibit cell migration and invasion of breast and prostate epithelial cells by upregulating Endoglin expression, the effect and molecular mechanism for lung cancer cell motility regulation remains elusive. Methods Human non-small cell lung cancer cells and HEK293FT cells were used to investigate the molecular mechanism of Hhex regulating lung cancer cell migration by using Western blot, immunoprecipitation, wound-healing scratch assay, laser confocal. Results Our data indicated that Hhex could inhibit cell migration and cell protrusion formation in lung cancer cells. In addition, Hhex inhibited CFL1 phosphorylation to keep its F-actin-severing activity. RHOGDIA was involved in Hhex-induced CFL1 phosphorylation regulation. Hhex enhanced RHOGDIA interaction with RHOA/CDC42, thus maintaining RHOA/CDC42 at an inactive form. Conclusion Collectively, these data indicate that Hhex inhibited the activation of RHOA/CDC42 by enhancing interaction of RHOGDIA with RHOA/CDC42, and then RHOA/ CDC42-p-CFL1 signaling pathway was blocked. Consequently, the formation of Filopodium and Lamellipodium on the cell surface was suppressed, and thus the ability of lung cancer cells to migrate was decreased accordingly. Our findings show Hhex plays an important role in regulating migration of lung cancer cells and may provide a potential target for lung cancer therapy.

2.5D Tractions in monocytes reveal mesoscale mechanics of podosomes during substrate indenting cell protrusion

Degradation and protrusion are key to cellular barrier breaching in cancer metastasis and leukocyte extravasation. Cancerous invadopodia and myelomonocytic podosomes are widely considered as structural tools facilitating these processes and are thus summarized under the term invadosomes. Despite similar behaviour on the individual scale, substantial differences have been reported to arise on the collective scale. They are considered to be a result of podosome mesoscale-connectivity. In this study, we investigated global in-plane and out-of-plane mechanical forces of podosome clusters in ER-Hoxb8 cell derived monocytes. We are able to correlate these forces with the interpodosomal connectivity. The observed traction and protrusion patterns fail to be explained by summation of single podosome mechanics. Instead, they appear to originate from superimposed mesoscale effects. Based on mechanistic and morphological similarities with epithelial monolayer mechanics, we propose a spatiotemporal model of podosome cluster mechanics capable of relating single to collective podosome mechanical behaviour. Our results suggest that network contraction-driven (in-plane) tractions lead to a buckling instability that contributes to the out-of-plane indentation into the substrate. First assigning an active mechanical role to the dorsal podosome actomyosin network, we aim at translating actomyosin hierarchy into scale dependency of podosome mechanics.

Chance that matter or matter of chance: changing prevalence of fundic gland polyps and proton pump inhibitors

Background: Proton pump inhibitors (PPI) are considered one of reasons for changing prevalence of gastric fundic gland polyps (FGP), not only in western world but trend is being seen in Asian countries as well. Aims and Objective: This study was designed to evaluate prevalence of FGP and to look into endoscopic and histological profile of these polyps in PPI users and non-PPI users. We also assessed background gastric mucosal histology in FGP patients. Materials and Methods: This is a retrospective observational study of 1800 cases. Medical records of patients who underwent esophagogastroduodenoscopy (EGD) in three gastroenterology centres between 2011 and 2019 were analysed at Noora super speciality Hospital, Kashmir; Northern India. Biopsy specimens of patients with FGP were reviewed by expert pathologists. PPI use was quantified as significant when Pantoprazole 40 mg per day or equivalent doses of other PPI was used four times or more per week for more than one year. Statistical Analysis was conducted using SPSS version 22. Results: FGP were most common, observed in 900 (50%) of all gastric polyp cases. PPI use one year and more was noted only in 360 (40%). FGP were mostly located in fundus 630 (70%), multiple in 840 (93.33%), with average size between 6 to 10 mm. On histology parietal cell hyperplasia, parietal cell protrusion and foveolar hyperplasia were seen in 666 (74%), 716(79.55%) and 254 (28.22%) cases respectively. Background gastric histology was normal in 543 (60.33%). Conclusions: FGP were most common gastric polyps in Northern India. We observed similar endoscopic and histological characters in FGP irrespective of whether cases were using PPI or not. Majority of cases had normal background gastric mucosal histology.

Cytoplasmic pressure maintains epithelial integrity and inhibits cell motility

Cytoplasmic pressure, a function of actomyosin contractility and water flow, can regulate cellular morphology and dynamics. In mesenchymal cells, cytoplasmic pressure powers cell protrusion through physiological three-dimensional extracellular matrices. However, the role of intracellular pressure in epithelial cells is relatively unclear. Here we find that high cytoplasmic pressure is necessary to maintain barrier function, one of the hallmarks of epithelial homeostasis. Further, our data show that decreased cytoplasmic pressure facilitates lamellipodia formation during the epithelial to mesenchymal transition (EMT). Critically, activation of the actin nucleating protein Arp2/3 is required for the reduction in cytoplasmic pressure and lamellipodia formation in response to treatment with hepatocyte growth factor (HGF) to induce EMT. Thus, elevated cytoplasmic pressure functions to maintain epithelial tissue integrity, while reduced cytoplasmic pressure triggers lamellipodia formation and motility during HGF-dependent EMT.

CD73 facilitates EMT progression and promotes lung metastases in triple-negative breast cancer

CD73 is a cell surface ecto-5′-nucleotidase, which converts extracellular adenosine monophosphate to adenosine. High tumor CD73 expression is associated with poor outcome among triple-negative breast cancer (TNBC) patients. Here we investigated the mechanisms by which CD73 might contribute to TNBC progression. This was done by inhibiting CD73 with adenosine 5′-(α, β-methylene) diphosphate (APCP) in MDA-MB-231 or 4T1 TNBC cells or through shRNA-silencing (sh-CD73). Effects of such inhibition on cell behavior was then studied in normoxia and hypoxia in vitro and in an orthotopic mouse model in vivo. CD73 inhibition, through shRNA or APCP significantly decreased cellular viability and migration in normoxia. Inhibition of CD73 also resulted in suppression of hypoxia-induced increase in viability and prevented cell protrusion elongation in both normoxia and hypoxia in cancer cells. Sh-CD73 4T1 cells formed significantly smaller and less invasive 3D organoids in vitro, and significantly smaller orthotopic tumors and less lung metastases than control shRNA cells in vivo. CD73 suppression increased E-cadherin and decreased vimentin expression in vitro and in vivo, proposing maintenance of a more epithelial phenotype. In conclusion, our results suggest that CD73 may promote early steps of tumor progression, possibly through facilitating epithelial–mesenchymal transition.