Simulated Microgravity Disrupts Cytoskeleton Organization and Increases Apoptosis of Rat Neural Crest Stem Cells Via Upregulating CXCR4 Expression and RhoA-ROCK1-p38 MAPK-p53 Signaling

The Role of CXC Chemokines in Cancer Progression

CXC chemokines are small chemotactic and secreted cytokines. Studies have shown that CXC chemokines are dysregulated in multiple types of cancer and are closely correlated with tumor progression. The CXC chemokine family has a dual function in tumor development, either tumor-promoting or tumor-suppressive depending on the context of cellular signaling. Recent evidence highlights the pro-tumorigenic properties of CXC chemokines in most human cancers. CXC chemokines were found to play pivotal roles in promoting angiogenesis, stimulating inflammatory responses, and facilitating tumor metastases. Enhanced expression of CXC chemokines is always signatured with inferior survival and prognosis. The levels of CXC chemokines in cancer patients are in dynamic change according to the tumor contexts (e.g., chemotherapy resistance and tumor recurrence after surgery). Thus, CXC chemokines have great potential to be used as diagnostic and prognostic biomarkers and therapeutic targets. Currently, the molecular mechanisms underlying the effect of CXC chemokines on tumor inflammation and metastasis remain unclear and application of antagonists and neutralizing antibodies of CXC chemokines signaling for cancer therapy is still not fully established. This article will review the roles of CXC chemokines in promoting tumorigenesis and progression and address the future research directions of CXC chemokines for cancer treatment.

Interaction Network Provides Clues on the Role of BCAR1 in Cellular Response to Changes in Gravity

When culturing cells in space or under altered gravity conditions on Earth to investigate the impact of gravity, their adhesion and organoid formation capabilities change. In search of a target where the alteration of gravity force could have this impact, we investigated p130cas/BCAR1 and its interactions more thoroughly, particularly as its activity is sensitive to applied forces. This protein is well characterized regarding its role in growth stimulation and adhesion processes. To better understand BCAR1′s force-dependent scaffolding of other proteins, we studied its interactions with proteins we had detected by proteome analyses of MCF-7 breast cancer and FTC-133 thyroid cancer cells, which are both sensitive to exposure to microgravity and express BCAR1. Using linked open data resources and our experiments, we collected comprehensive information to establish a semantic knowledgebase and analyzed identified proteins belonging to signaling pathways and their networks. The results show that the force-dependent phosphorylation and scaffolding of BCAR1 influence the structure, function, and degradation of intracellular proteins as well as the growth, adhesion and apoptosis of cells similarly to exposure of whole cells to altered gravity. As BCAR1 evidently plays a significant role in cell responses to gravity changes, this study reveals a clear path to future research performing phosphorylation experiments on BCAR1.

Molecular genetic analysis of neural stem cells after space flight and simulated microgravity on earth

Understanding how stem cells adapt to space flight conditions is fundamental for human space missions and extraterrestrial settlement. We analyzed gene expression in boundary cap neural crest stem cells (BCs), which are attractive for regenerative medicine by their ability to promote proliferation and survival of cocultured and co-implanted cells. BCs were launched to space (space exposed cells) (SEC), onboard sounding rocket MASER 14 as free-floating neurospheres or in a bioprinted scaffold. For comparison, BCs were placed in a random positioning machine (RPM) to simulate microgravity on earth (RPM cells) or were cultured under control conditions in the laboratory. Using next-generation RNA sequencing and data post-processing, we discovered that SEC upregulated genes related to proliferation and survival, whereas RPM cells upregulated genes associated with differentiation and inflammation. Thus, (i) space flight provides unique conditions with distinctly different effects on the properties of BC compared to earth controls, and (ii) the space flight exposure induces postflight properties that reinforce the utility of BC for regenerative medicine and tissue engineering.

Simulated Microgravity Inhibits the Proliferation of Chang Liver Cells by Attenuation of the Major Cell Cycle Regulators and Cytoskeletal Proteins

Simulated microgravity (SMG) induced the changes in cell proliferation and cytoskeleton organization, which plays an important factor in various cellular processes. The inhibition in cell cycle progression has been considered to be one of the main causes of proliferation inhibition in cells under SMG, but their mechanisms are still not fully understood. This study aimed to evaluate the effects of SMG on the proliferative ability and cytoskeleton changes of Chang Liver Cells (CCL-13). CCL-13 cells were induced SMG by 3D clinostat for 72 h, while the control group were treated in normal gravity at the same time. The results showed that SMG reduced CCL-13 cell proliferation by an increase in the number of CCL-13 cells in G0/G1 phase. This cell cycle phase arrest of CCL-13 cells was due to a downregulation of cell cycle-related proteins, such as cyclin A1 and A2, cyclin D1, and cyclin-dependent kinase 6 (Cdk6). SMG-exposed CCL-13 cells also exhibited a downregulation of α-tubulin 3 and β-actin which induced the cytoskeleton reorganization. These results suggested that the inhibited proliferation of SMG-exposed CCL-13 cells could be associate with the attenuation of major cell cycle regulators and main cytoskeletal proteins.

Inhibition of invadopodia formation by diosgenin in tumor cells

Diosgenin is a type of steroid extracted from the rhizome of Dioscorea plants. In traditional Chinese medicine, Dioscorea has the effect of ‘eliminating phlegm, promoting digestion, relaxing tendons, promoting blood circulation and inhibiting malaria’. Recent studies have confirmed that diosgenin exhibits a number of pharmacological effects, including antitumor activities. Through its antitumor effect, diosgenin is able to block tumor progression and increase the survival rate of patients with cancer; ultimately improving their quality of life. However, the mechanism underlying its pharmacological action remains unclear. Once tumor cells reach a metastatic phase, it can be fatal. Increased migration and invasiveness are the hallmarks of metastatic tumor cells. Invadopodia formation is key to maintaining the high migration and invasive ability of tumor cells. Invadopodia are a type of membrane structure process rich in filamentous-actin and are common in highly invasive tumor cells. In addition to actin, numerous actin regulators, including cortical actin-binding protein (Cortactin), accumulate in invadopodia. Cortactin is a microfilament actin-binding protein with special repetitive domains that are directly involved in the formation of the cortical microfilament actin cell skeleton. Cortactin is also one of the main substrates of intracellular Src-type tyrosine protein kinases and represents a highly conserved family of intracellular cortical signaling proteins. In recent years, great progress has been made in understanding the role of Cortactin and its molecular mechanism in cell motility. However, the diosgenin-Cortactin-invadopodia mechanism is still under investigation. Therefore, the present review focused on the current research on the regulation of invadopodia by diosgenin via Cortactin.

Microgravity effects on frozen human sperm samples

PURPOSE

Microgravity has severe effects on cellular and molecular structures as well as on metabolic interactions. The aim of this study is to investigate the effects of microgravity (μg) exposure on human frozen sperm samples.

METHODS

Sibling samples from 15 normozoospermic healthy donors were frozen using glycerol as cryoprotectant and analyzed under microgravity and ground conditions. Microgravity was obtained by parabolic flights using a CAP10B plane. The plane executed 20 parabolic maneuvers with a mean of 8.5 s of microgravity for each parabola.

RESULTS

Frozen sperm samples preserved in cryostraws and stored in a secure and specific nitrogen vapor cryoshipper do not suffer significant alterations after μg exposure. Comparing the study group (μg) and the control group (1 g), similar results were obtained in the main parameters studied: sperm motility (M/ml) 13.72 ± 12.57 vs 13.03 ± 12.13 (- 0.69 95% CI [- 2.9; 1.52]), progressive a + b sperm motility (%) 21.83 ± 11.69 vs 22.54 ± 12.83 (0.03 95% CI [- 0.08; 0.15]), sperm vitality (%) 46.42 ± 10.81 vs 44.62 ± 9.34 (- 0.04 95% CI [- 0.13; 0.05]), morphologically normal spermatozoa (%) 7.03 ± 2.61 vs 8.09 ± 3.61 (0.12 95% CI [0.01; 0.24]), DNA sperm fragmentation by SCD (%) 13.33 ± 5.12 vs 13.88 ± 6.14 (0.03 95% CI [- 0.09; 0.16]), and apoptotic spermatozoa by MACS (%) 15.47 ± 15.04 vs 23.80 ± 23.63 (- 0.20 95% CI [- 0.66; 1.05]).

CONCLUSION

The lack of differences obtained between frozen samples exposed to μg and those maintained in ground conditions provides the possibility of considering the safe transport of human male gametes to space. Nevertheless, further research is needed to validate the results and to consider the possibility of creating a human sperm bank outside the Earth.

TRIAL REGISTRATION NUMBER

ClinicalTrials.gov: NCT03760783.

RETRACTED: Down-regulated microRNA-195-5p and up-regulated CXCR4 attenuates the heart function injury of heart failure mice via inactivating JAK/STAT pathway

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the integrity of the images in Figure 6, which appear to contain suspected image duplications, as detailed here: https://pubpeer.com/publications/A31DE9EEF13ED6B88BCC86A9CAC8D9 and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. Most of these image duplications involve either pasting portions of one image into another, or rotating/flipping the image. Numerous additional suspected image duplications were detected within Figures 2A and 7A. The journal requested the corresponding author comment on these concerns and provide the raw data. The authors did not respond to this request and therefore the Editor-in-Chief decided to retract the article.

Simulated microgravity enhances CDDP-induced apoptosis signal via p53-independent mechanisms in cancer cells

Although the biological systems in the human body are affected by the earth’s gravity, information about the underlying molecular mechanisms is limited. For example, apoptotic signaling is enhanced in cancer cells subjected to microgravity. We reasoned that signaling regulated by p53 may be involved because of its role in apoptosis. Therefore, we aimed to clarify the molecular mechanisms of modified cis-diamminedichloroplatinum (CDDP)-sensitivity under simulated microgravity by focusing on p53-related cell death mechanisms. Immunoblotting analyses indicated that, under microgravity, CDDP-induced ATM/p53 signaling increased and caspase-3 was cleaved earlier. However, microgravity decreased the levels of expression of p53 targets BAX and CDKN1A. Interestingly, microgravity increased the PTEN, DRAM1, and PRKAA1 mRNA levels. However, microgravity decreased the levels of mTOR and increased the LC3-II/I ratio, suggesting the activation of autophagy. The CDDP-induced cleavage of caspase-3 was increased during the early phase in Group MG (+), and cleaved caspase-3 was detected even in Group MG (+) with constitutive expression of a mutant type of p53 (hereafter, “+” indicates CDDP treatment). These results interestingly indicate that microgravity altered CDDP sensitivity through activation of caspase-3 by p53-independent mechanism.

Effect of Weightlessness on the 3D Structure Formation and Physiologic Function of Human Cancer Cells

With the rapid development of modern medical technology and the deterioration of living environments, cancer, the most important disease that threatens human health, has attracted increasing concerns. Although remarkable achievements have been made in tumor research during the past several decades, a series of problems such as tumor metastasis and drug resistance still need to be solved. Recently, relevant physiological changes during space exploration have attracted much attention. Thus, space exploration might provide some inspiration for cancer research. Using on ground different methods in order to simulate microgravity, structure and function of cancer cells undergo many unique changes, such as cell aggregation to form 3D spheroids, cell-cycle inhibition, and changes in migration ability and apoptosis. Although numerous better experiments have been conducted on this subject, the results are not consistent. The reason might be that different methods for simulation have been used, including clinostats, random positioning machine (RPM) and rotating wall vessel (RWV) and so on. Therefore, we review the relevant research and try to explain novel mechanisms underlying tumor cell changes under weightlessness.

Modulation of Iberian Ribbed Newt Complement Component C3 by Stressors Similar to those Encountered during a Stay Onboard the International Space Station

The complement system plays an important role in inflammation, innate and acquired immunity, as well as homeostasis. Despite these functions, the effects of spaceflight conditions on the complement system have not yet been intensively studied. Consequently, we investigated the effects of five types of chronic stressors, similar to those encountered during a stay onboard the International Space Station, on C3 expression in larvae of the urodele amphibian Pleurodeles waltl. We focused on C3 because it is a critical component of this system. These studies were completed by the analysis of adult mice exposed to two models of inflight stressors. Our data show that simulating space radiation, or combining a modification of the circadian rhythm with simulated microgravity, affects the amount of C3 proteins. These results suggest that C3 expression could be modified under real spaceflight conditions, potentially increasing the risk of inflammation and associated tissue damage.

Microgravity induces autophagy via mitochondrial dysfunction in human Hodgkin's lymphoma cells

Gravitational forces can impose physical stresses on the human body as it functions to maintain homeostasis. It has been reported that astronauts exposed to microgravity experience altered biological functions and many subsequent studies on the effects of microgravity have therefore been conducted. However, the anticancer mechanisms of simulated microgravity remain unclear. We previously showed that the proliferation of human Hodgkin's lymphoma (HL) cells was inhibited when these cells were cultured in time-averaged simulated microgravity (taSMG). In the present study, we investigated whether taSMG produced an anticancer effect. Exposure of human HL cells to taSMG for 2 days increased their reactive oxygen species (ROS) production and NADPH oxidase family gene expression, while mitochondrial mass, ATPase, ATP synthase, and intracellular ATP levels were decreased. Furthermore, human HL cells exposed to taSMG underwent autophagy via AMPK/Akt/mTOR and MAPK pathway modulation; such autophagy was inhibited by the ROS scavenger N-acetylcysteine (NAC). These results suggest an innovative therapeutic approach to HL that is markedly different from conventional chemotherapy and radiotherapy.

Cardiovascular progenitor cells cultured aboard the International Space Station exhibit altered developmental and functional properties

The heart and its cellular components are profoundly altered by missions to space and injury on Earth. Further research, however, is needed to characterize and address the molecular substrates of such changes. For this reason, neonatal and adult human cardiovascular progenitor cells (CPCs) were cultured aboard the International Space Station. Upon return to Earth, we measured changes in the expression of microRNAs and of genes related to mechanotransduction, cardiogenesis, cell cycling, DNA repair, and paracrine signaling. We additionally assessed endothelial-like tube formation, cell cycling, and migratory capacity of CPCs. Changes in microRNA expression were predicted to target extracellular matrix interactions and Hippo signaling in both neonatal and adult CPCs. Genes related to mechanotransduction (YAP1, RHOA) were downregulated, while the expression of cytoskeletal genes (VIM, NES, DES, LMNB2, LMNA), non-canonical Wnt ligands (WNT5A, WNT9A), and Wnt/calcium signaling molecules (PLCG1, PRKCA) was significantly elevated in neonatal CPCs. Increased mesendodermal gene expression along with decreased expression of mesodermal derivative markers (TNNT2, VWF, and RUNX2), reduced readiness to form endothelial-like tubes, and elevated expression of Bmp and Tbx genes, were observed in neonatal CPCs. Both neonatal and adult CPCs exhibited increased expression of DNA repair genes and paracrine factors, which was supported by enhanced migration. While spaceflight affects cytoskeletal organization and migration in neonatal and adult CPCs, only neonatal CPCs experienced increased expression of early developmental markers and an enhanced proliferative potential. Efforts to recapitulate the effects of spaceflight on Earth by regulating processes described herein may be a promising avenue for cardiac repair.

Regulation of the Response of Caenorhabditis elegans to Simulated Microgravity by p38 Mitogen-Activated Protein Kinase Signaling

The in vivo function of p38 mitogen-activated protein kinase (MAPK) signaling in regulating the response to simulated microgravity is still largely unclear. Using Caenorhabditis elegans as an assay system, we investigated the in vivo function of p38 MAPK signaling in regulating the response of animals to simulated microgravity and the underlying molecular mechanism. Simulated microgravity treatment significantly increased the transcriptional expressions of genes (pmk-1, sek-1, and nsy-1) encoding core p38 MAPK signaling pathway and the expression of phosphorylated PMK-1/p38 MAPK. The pmk-1, sek-1, or nsy-1 mutant was susceptible to adverse effects of simulated microgravity. The intestine-specific activity of PMK-1 was required for its function in regulating the response to simulated microgravity, and the entire p38 MAPK signaling pathway could act in the intestine to regulate the response to simulated microgravity. In the intestine, SKN-1 and ATF-7, two transcriptional factors, were identified as downstream targets for PMK-1 in regulating the response to simulated microgravity. Therefore, the activation of p38 MAPK signaling may mediate a protection mechanism for nematodes against the adverse effects of simulated microgravity. Additionally, our results highlight the potential crucial role of intestinal cells in response to simulated microgravity in nematodes.

The influence of simulated microgravity on proliferation and apoptosis in U251 glioma cells

Several studies have indicated that microgravity can influence cellular progression, proliferation, and apoptosis in tumor cell lines. In this study, we observed that simulated microgravity inhibited proliferation and induced apoptosis in U251 malignant glioma (U251MG) cells. Furthermore, expression of the apoptosis-associated proteins, p21 and insulin-like growth factor binding protein-2 (IGFBP-2), was upregulated and downregulated, respectively, following exposure to simulated microgravity. These findings indicate that simulated microgravity inhibits proliferation while inducing apoptosis of U251MG cells. The associated effects appear to be mediated by inhibition of IGFBP-2 expression and stimulation of p21 expression. This suggests that simulated microgravity might represent a promising method to discover new targets for glioma therapeutic strategy.

Hypoxia and hyperoxia differentially control proliferation of rat neural crest stem cells via distinct regulatory pathways of the HIF1α-CXCR4 and TP53-TPM1 proteins

BACKGROUND

Neural crest stem cells (NCSCs) are a population of adult multipotent stem cells. We are interested in studying whether oxygen tensions affect the capability of NCSCs to self-renew and repair damaged tissues. NCSCs extracted from the hair follicle bulge region of the rat whisker pad were cultured in vitro under different oxygen tensions.

RESULTS

We found significantly increased and decreased rates of cell proliferation in rat NCSCs (rNCSCs) cultured, respectively, at 0.5% and 80% oxygen levels. At 0.5% oxygen, the expression of both hypoxia-inducible factor (HIF) 1α and CXCR4 was greatly enhanced in the rNCSC nuclei and was suppressed by incubation with the CXCR4-specific antagonist AMD3100. In addition, the rate of cell apoptosis in the rNCSCs cultured at 80% oxygen was dramatically increased, associated with increased nuclear expression of TP53, decreased cytoplasmic expression of TPM1 (tropomyosin-1), and increased nuclear-to-cytoplasmic translocation of S100A2. Incubation of rNCSCs with the antioxidant N-acetylcysteine (NAC) overcame the inhibitory effect of 80% oxygen on proliferation and survival of rNCSCs.

CONCLUSIONS

Our results show for the first time that extreme oxygen tensions directly control NCSC proliferation differentially via distinct regulatory pathways of proteins, with hypoxia via the HIF1α-CXCR4 pathway and hyperoxia via the TP53-TPM1 pathway. Developmental Dynamics 246:162-185, 2017. © 2016 Wiley Periodicals, Inc.

Degradomics in Neurotrauma: Profiling Traumatic Brain Injury

Degradomics has recently emerged as a subdiscipline in the omics era with a focus on characterizing signature breakdown products implicated in various disease processes. Driven by promising experimental findings in cancer, neuroscience, and metabolomic disorders, degradomics has significantly promoted the notion of disease-specific "degradome." A degradome arises from the activation of several proteases that target specific substrates and generate signature protein fragments. Several proteases such as calpains, caspases, cathepsins, and matrix metalloproteinases (MMPs) are involved in the pathogenesis of numerous diseases that disturb the physiologic balance between protein synthesis and protein degradation. While regulated proteolytic activities are needed for development, growth, and regeneration, uncontrolled proteolysis initiated under pathological conditions ultimately culminates into apoptotic and necrotic processes. In this chapter, we aim to review the protease-substrate repertoires in neural injury concentrating on traumatic brain injury. A striking diversity of protease substrates, essential for neuronal and brain structural and functional integrity, namely, encryptic biomarker neoproteins, have been characterized in brain injury. These include cytoskeletal proteins, transcription factors, cell cycle regulatory proteins, synaptic proteins, and cell junction proteins. As these substrates are subject to proteolytic fragmentation, they are ceaselessly exposed to activated proteases. Characterization of these molecules allows for a surge of "possible" therapeutic approaches of intervention at various levels of the proteolytic cascade.