Oncologic Safety and Efficacy of Cell-Assisted Lipotransfer for Breast Reconstruction in a Murine Model of Residual Breast Cancer.

BACKGROUND: Cell-assisted lipotransfer (CAL) is a novel technique for fat grafting that combines the grafting of autologous fat and adipose-derived stromal cells (ASCs) to enhance fat graft retention; however, its oncologic safety is controversial. METHODS: Herein, we investigated the oncologic safety of CAL for breast reconstruction using a murine model of residual breast cancer. Various concentrations of 4T1 cells (murine breast cancer cells) were injected into female mastectomized BALB/c mice to determine the appropriate concentration for injection. One week after injection, mice were divided into control (100 µL fat), low CAL (2.5 × 105 ASCs/100 µL fat), and high CAL (1.0 × 106 ASCs/100 µL fat) groups, and fat grafting was performed. The injection of 5.0 × 103 4T1 cells was appropriate to produce a murine model of residual breast cancer. RESULTS: The weight of the fat tumor mass was significantly higher in the high CAL group than in the other groups (p < 0.05). However, the estimated tumor weight was not significantly different between the groups. Additionally, the fat graft survival rate was significantly higher in the high CAL group than in the control and low CAL groups (p < 0.05). No significant difference was noted in the percentage of Ki-67-positive cells, suggesting that tumor proliferation was not significantly different between the groups. CONCLUSION: In summary, CAL significantly improved fat graft survival without affecting tumor size and proliferation in a murine model of residual breast cancer. These results highlight the oncologic safety of CAL for breast reconstruction. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Lipid metabolic reprogramming by hypoxia-inducible factor-1 in the hypoxic tumour microenvironment.

Cancer cells rewire metabolic processes to adapt to the nutrient- and oxygen-deprived tumour microenvironment, thereby promoting their proliferation and metastasis. Previous research has shown that modifying glucose metabolism, the Warburg effect, makes glycolytic cancer cells more invasive and aggressive. Lipid metabolism has also been receiving attention because lipids function as energy sources and signalling molecules. Because obesity is a risk factor for various cancer types, targeting lipid metabolism may be a promising cancer therapy. Here, we review the lipid metabolic reprogramming in cancer cells mediated by hypoxia-inducible factor-1 (HIF-1). HIF-1 is the master transcription factor for tumour growth and metastasis by transactivating genes related to proliferation, survival, angiogenesis, invasion, and metabolism. The glucose metabolic shift (the Warburg effect) is mediated by HIF-1. Recent research on HIF-1-related lipid metabolic reprogramming in cancer has confirmed that HIF-1 also modifies lipid accumulation, ß-oxidation, and lipolysis in cancer, triggering its progression. Therefore, targeting lipid metabolic alterations by HIF-1 has therapeutic potential for cancer. We summarize the role of the lipid metabolic shift mediated by HIF-1 in cancer and its putative applications for cancer therapy.

Histone demethylase PHF2 activates CREB and promotes memory consolidation.

Long-term memory formation is attributed to experience-dependent gene expression. Dynamic changes in histone methylation are essential for the epigenetic regulation of memory consolidation-related genes. Here, we demonstrate that the plant homeodomain finger protein 2 (PHF2) histone demethylase is upregulated in the mouse hippocampus during the experience phase and plays an essential role in memory formation. PHF2 promotes the expression of memory-related genes by epigenetically reinforcing the TrkB-CREB signaling pathway. In behavioral tests, memory formation is enhanced by transgenic overexpression of PHF2 in mice, but is impaired by silencing PHF2 in the hippocampus. Electrophysiological studies reveal that PHF2 elevates field excitatory postsynaptic potential (fEPSP) and NMDA receptor-mediated evoked excitatory postsynaptic current (EPSC) in CA1 pyramidal neurons, suggesting that PHF2 promotes long-term potentiation. This study provides insight into the epigenetic regulation of learning and memory formation, which advances our knowledge to improve memory in patients with degenerative brain diseases.

How cancer cells remodel lipid metabolism: strategies targeting transcription factors.

Reprogramming of lipid metabolism has received increasing recognition as a hallmark of cancer cells because lipid dysregulation and the alteration of related enzyme profiles are closely correlated with oncogenic signals and malignant phenotypes, such as metastasis and therapeutic resistance. In this review, we describe recent findings that support the importance of lipids, as well as the transcription factors involved in cancer lipid metabolism. With recent advances in transcription factor analysis, including computer-modeling techniques, transcription factors are emerging as central players in cancer biology. Considering the limited number and the crucial role of transcription factors associated with lipid rewiring in cancers, transcription factor targeting is a promising potential strategy for cancer therapy.

Compact Fat Grafting: A Novel Method to Improve Graft Retention Through Modulation of Adipocyte Size.

BACKGROUND: The viable zone where adipocytes and/or adipose-derived stem cells survive is present at the surface of graft fat tissue; however, there is controversy regarding the zone thickness. Graft retention could be improved if more adipocytes are included in the zone. OBJECTIVES: We hypothesize that a temporary reduction in adipocyte size prior to grafting could increase the number of adipocytes in the viable zone. We reduced the adipocyte size by treatment with MLN4924, which controls lipid accumulation in adipocytes, and investigated the histological and microenvironmental changes in grafted fat. METHODS: Subcutaneous fat harvested from wild-type C57BL/6J mice was chopped into small pieces; treated with dimethyl sulfoxide (control group), 0.25 µM MLN4924, or 0.5 µM MLN4924 for 4 days; and grafted into recipient C57BL/6J mice at the supraperiosteal plane of the skull. RESULTS: The reduced adipocyte size in response to MLN4924 treatment was restored within 8 weeks after fat grafting. The MLN4924-treated groups exhibited substantially greater graft volume, lower tissue hypoxia, and higher production of M2 macrophages compared with the control group. CONCLUSIONS: Grafting with compact fat that had smaller adipocytes improved the microenvironment by modulating tissue hypoxia and macrophage polarization, leading to improved graft retention. Therefore, compact fat grafting may offer a new clinical strategy without the need for stem cell manipulation.

Targeted Downregulation of kdm4a Ameliorates Tau-engendered Defects in Drosophila melanogaster.

BACKGROUND: Tauopathies, a class of neurodegenerative diseases that includes Alzheimer's disease (AD), are characterized by the deposition of neurofibrillary tangles composed of hyperphosphorylated tau protein in the human brain. As abnormal alterations in histone acetylation and methylation show a cause and effect relationship with AD, we investigated the role of several Jumonji domain-containing histone demethylase (JHDM) genes, which have yet to be studied in AD pathology. METHODS: To examine alterations of several JHDM genes in AD pathology, we performed bioinformatics analyses of JHDM gene expression profiles in brain tissue samples from deceased AD patients. Furthermore, to investigate the possible relationship between alterations in JHDM gene expression profiles and AD pathology in vivo, we examined whether tissue-specific downregulation of JHDM Drosophila homologs (kdm) can affect tauR406W-induced neurotoxicity using transgenic flies containing the UAS-Gal4 binary system. RESULTS: The expression levels of JHDM1A, JHDM2A/2B, and JHDM3A/3B were significantly higher in postmortem brain tissue from patients with AD than from non-demented controls, whereas JHDM1B mRNA levels were downregulated in the brains of patients with AD. Using transgenic flies, we revealed that knockdown of kdm2 (homolog to human JHDM1), kdm3 (homolog to human JHDM2), kdm4a (homolog to human JHDM3A), or kdm4b (homolog to human JHDM3B) genes in the eye ameliorated the tauR406W-engendered defects, resulting in less severe phenotypes. However, kdm4a knockdown in the central nervous system uniquely ameliorated tauR406W-induced locomotion defects by restoring heterochromatin. CONCLUSION: Our results suggest that downregulation of kdm4a expression may be a potential therapeutic target in AD.

CST3 and GDF15 ameliorate renal fibrosis by inhibiting fibroblast growth and activation.

The final strategies to care patients with end-stage renal fibrosis rely on dialysis and kidney transplantation. Because such treatments are invasive and cause health problems eventually, it is necessary to develop new therapeutic strategies for delaying the disease progress. We here searched for cytokines showing an anti-fibrotic activity in cell-based experiments. Cystatin C (CST3) and Growth differentiation factor 15 (GDF15) were identified to have anti-fibrotic activities in a cytokine array screening. In primary fibroblasts isolated from the mouse kidneys subjected to ureteral obstruction-induced fibrosis, each cytokine induced apoptotic cell death and reduced collagen production. These anti-fibrotic effects were further augmented by co-administration of both cytokines. Mechanistically, CST3 and GDF15 were found to block the TGF-ß receptor and the N-Myc signaling pathways, respectively. In mice with unilateral ureter obstruction, each cytokine and the combination of two cytokines effectively reduced the fibrotic burden in the subjected kidneys. Therefore, we propose that CST3 and GDF15 could be potential candidates for biopharmaceutics to ameliorate renal fibrosis.

Inhibition of neddylation facilitates cell migration through enhanced phosphorylation of caveolin-1 in PC3 and U373MG cells.

BACKGROUND: Protein neddylation is a post-translational modification by a covalent conjugation with the neural precursor cell expressed, developmentally downregulated 8 (NEDD8). Although this process has been reported to participate in diverse cellular signaling, little is known about its role in cancer cell migration. Given a recent proteomics report showing that NEDD8 is downregulated in prostate cancer tissues versus normal prostate tissues, we tested the possibility that neddylation plays a role in cancer evolution, and then tried to identify target proteins of the neddylation. METHODS: The neddylation process was inhibited by transfecting cancer cells with NEDD8-targeting siRNAs or by treating the cells with a NAE1 inhibitor MLN4924. Cell migration was evaluated by an in vitro wound-healing assay and a Transwell migration assay. His/NEDD8-conjugated proteins were pulled down with nickel-affinity beads under a denaturing condition, and identified by Western blotting. All data were processed using the Microsoft Excel program and analyzed statistically by two-sided, unpaired Student's t-test. RESULTS: Caveolin-1, which plays a critical role in cell migration, was identified to be conjugated with NEDD8. When the neddylation was inhibited, the phosphorylation of caveolin-1 at Tyr14 was augmented in PC3 and U373MG cells, thereby leading to increased cell migration. Such consequences by neddylation inhibition were abolished in the presence of a Src family kinase inhibitor PP2. CONCLUSIONS: NEDD8 seems to inhibit the Src-mediated phosphorylation of caveolin-1 by modifying the structure of caveolin-1 protein, which blocks the migration of cancer cells. Although the neddylation process is currently regarded as an emerging target for cancer therapy, our results suggest the possibility that the inhibition of neddylation could facilitate cancer invasion or metastasis at least in some types of cancers.

Sirtuin 1 modulates cellular responses to hypoxia by deacetylating hypoxia-inducible factor 1alpha.

To survive in hypoxic environments, organisms must be able to cope with redox imbalance and oxygen deficiency. The SIRT1 deacetylase and the HIF-1alpha transcription factor act as redox and oxygen sensors, respectively. Here, we found that SIRT1 binds to HIF-1alpha and deacetylates it at Lys674, which is acetylated by PCAF. By doing so, SIRT1 inactivated HIF-1alpha by blocking p300 recruitment and consequently repressed HIF-1 target genes. During hypoxia, SIRT1 was downregulated due to decreased NAD(+) levels, which allowed the acetylation and activation of HIF-1alpha. Conversely, when the redox change was attenuated by blocking glycolysis, SIRT1 was upregulated, leading to the deacetylation and inactivation of HIF-1alpha even in hypoxia. In addition, we confirmed the SIRT1-HIF-1alpha interaction in hypoxic mouse tissues and observed in vivo that SIRT1 has negative effects on tumor growth and angiogenesis. Our results suggest that crosstalk between oxygen- and redox-responsive signal transducers occurs through the SIRT1-HIF-1alpha interaction.

Jumonji histone demethylases as emerging therapeutic targets.

The methylation status of lysine residues in histones determines the transcription of surrounding genes by modulating the chromatin architecture. Jumonji domain-containing histone-lysine demethylases (Jmj-KDMs) remove the methyl moiety from lysine residues in histones by utilizing Fe(2+) and α-ketoglutarate. Since genetic alterations in Jmj-KDMs occur in various human cancers, the roles of Jmj-KDMs in cancer development and progression have been investigated, but still controversial. The KDM7 subfamily, which belongs to the Jmj-KDM family, is an emerging class of transcriptional coactivators because its members erase the repressive marks H3K9me2/1, H3K27me2/1, and H4K20 me1. Recently, KDM7C (alternatively named PHF2) was discovered as a new KDM7 member and identified to play a tumor-suppressive role through the reinforcement of p53-driven growth arrest and apoptosis. In this article, we generally reviewed the roles of Jmj-KDMs in human cancers and more discussed the molecular functions and the clinical significances of KDM7C.

HIF-1α-mediated upregulation of TASK-2 K⁺ channels augments Ca²âº signaling in mouse B cells under hypoxia.

The general consensus is that immune cells are exposed to physiological hypoxia in vivo (PhyO2, 2-5% P(O2)). However, functional studies of B cells in hypoxic conditions are sparse. Recently, we reported the expression in mouse B cells of TASK-2, a member of pH-sensitive two-pore domain K(+) channels with background activity. In this study, we investigated the response of K(+) channels to sustained PhyO2 (sustained hypoxia [SH], 3% P(O2) for 24 h) in WEHI-231 mouse B cells. SH induced voltage-independent background K(+) conductance (SH-K(bg)) and hyperpolarized the membrane potential. The pH sensitivity and the single-channel conductance of SH-K(bg) were consistent with those of TASK-2. Immunoblotting assay results showed that SH significantly increased plasma membrane expressions of TASK-2. Conversely, SH failed to induce any current following small interfering (si)TASK-2 transfection. Similar hypoxic upregulation of TASK-2 was also observed in splenic primary B cells. Mechanistically, upregulation of TASK-2 by SH was prevented by si hypoxia-inducible factor-1α (HIF-1α) transfection or by YC-1, a pharmacological HIF-1α inhibitor. In addition, TASK-2 current was increased in WEHI-231 cells overexpressed with O2-resistant HIF-1α. Importantly, [Ca(2+)]c increment in response to BCR stimulation was significantly higher in SH-exposed B cells, which was abolished by high K(+)-induced depolarization or by siTASK-2 transfection. The data demonstrate that TASK-2 is upregulated under hypoxia via HIF-1α-dependent manner in B cells. This is functionally important in maintaining the negative membrane potential and providing electrical driving force to control Ca(2+) influx.

ITF2 prevents activation of the ß-catenin-TCF4 complex in colon cancer cells and levels decrease with tumor progression.

BACKGROUND & AIMS: Immunoglobulin transcription factor 2 (ITF2) was believed to promote neoplastic transformation via activation of ß-catenin. However, ITF2 recently was reported to suppress colon carcinogenesis. We investigated the roles of ITF2 in colorectal cancer cell lines and tumor formation and growth in mice. METHODS: Levels of ITF2, ß-catenin, and c-Myc were measured in 12 human colorectal tumor samples and by immunohistochemistry. ITF2 regulation of ß-catenin and T-cell factor (TCF) were analyzed using luciferase reporter, reverse-transcription quantitative polymerase chain reaction, flow cytometry, and immunoblot analyses. Mice were given subcutaneous injections of human colorectal cancer cell lines that stably express ITF2, small hairpin RNAs to reduce levels of ITF2, or control plasmids; xenograft tumor growth was assessed. Human colorectal carcinoma tissue arrays were used to associate levels of ITF2 expression and clinical outcomes. RESULTS: Levels of ß-catenin, cMyc, and ITF2 were increased in areas of human colon adenomas and carcinomas, compared with nontumor areas of the same tissues. ITF2 levels were reduced and cMyc levels were increased in areas of carcinoma, compared with adenoma. In human colorectal cancer cell lines, activation of the ß-catenin-TCF4 complex and expression of its target genes were regulated negatively by ITF2. ITF2 inhibited formation of the ß-catenin-TCF4 complex by competing with TCF4 for ß-catenin binding. Stable transgenic expression of ITF2 in human colorectal cancer cell lines reduced their proliferation and tumorigenic potential in mice, whereas small hairpin RNA knockdown of ITF2 promoted growth of xenograft tumors in mice. In an analysis of colorectal tumor tissue arrays, loss of ITF2 from colorectal tumor tissues was associated with poor outcomes of patients. A gene set enrichment analysis supported the negative correlation between the level of ITF2 and activity of the ß-catenin-TCF4 complex. CONCLUSIONS: In human colorectal cancer cell lines and tissue samples, ITF2 appears to prevent activation of the ß-catenin-TCF4 complex and transcription of its gene targets. Loss of ITF2 promotes the ability of colorectal cancer cells to form xenograft tumors, and is associated with tumor progression and shorter survival times of patients.

FBXO11 represses cellular response to hypoxia by destabilizing hypoxia-inducible factor-1α mRNA.

The transcriptional factor hypoxia-inducible factor-1α (HIF-1α) is induced under hypoxia and plays crucial roles in cancer progression and angiogenesis. Protein arginine methyltransferases (PRMTs), 11 isoforms of which have been identified so far, modulates the functions of diverse proteins by catalyzing arginine methylation in post-translational level. PRMT9 (alternatively named FBXO11) and PRMT11 (FBXO10) are expected to have the E3 ubiquitin ligase activity through their F-box domains as well as the methyltrasferase activity. Given previous studies examining roles of 8 PRMT isoforms (PRMT1-8) in the HIF-1 signaling pathway, PRMT1 and PRMT5 were demonstrated to regulate HIF-1α expression in opposite ways. We herein examined if FBXO10 and FBXO11 participate in the HIF-1 signaling pathway. Consequently, the siRNA-mediated knockdown of FBXO11 facilitated HIF-1α expression in various cancer cells and HIF-1-driven gene expressions, but the FBXO10 knockdown did not. Mechanistically, FBXO11 was found to inhibit de novo synthesis of HIF-1α protein by destabilizing HIF-1α mRNA. Since a FBXO11 mutant lacking F-box failed to reverse the HIF-1α expression by FBXO11 knockdown, the FBXO11 regulation of HIF-1α may be attributed to the ubiquitination of some proteins controlling HIF-1α mRNA stability. Considering the oncogenic roles of HIF-1α, FBXO11 is suggested to act as a tumor suppressor and also to be a potential target for cancer therapy.

HIF-1α Upregulation due to Depletion of the Free Ubiquitin Pool.

Hypoxia-inducible factor 1alpha (HIF-1α), which transactivates a variety of hypoxia-induced genes, is rapidly degraded under nomoxia through the hydroxylation-ubiquitination-proteasome pathway. In this study, we addressed how HIF-1α is stabilized by proteasome inhibitors. The ubiquitin pool was rapidly reduced after proteasome inhibition, followed by the accumulation of non-ubiquitinated HIF-1α. The poly-ubiquitination of HIF-1α was resumed by restoration of free ubiquitin, which suggests that the HIF-1α stabilization under proteasome inhibition is attributed to depletion of the free ubiquitin pool. Ni(2+) and Zn(2+) also stabilized HIF-1α with depletion of the free ubiquitin pool and these effects of metal ions were attenuated by restoration of free ubiquitin. Ni(2+) and Zn(2+) may disturb the recycling of free ubiquitin, as MG132 does. Based on these results, the state of the ubiquitin pool seems to be another critical factor determining the cellular level of HIF-1α.

Deferoxamine Improves Alveolar and Pulmonary Vascular Development by Upregulating Hypoxia-inducible Factor-1α in a Rat Model of Bronchopulmonary Dysplasia.

Fetal lung development normally occurs in a hypoxic environment. Hypoxia-inducible factor (HIF)-1α is robustly induced under hypoxia and transactivates many genes that are essential for fetal development. Most preterm infants are prematurely exposed to hyperoxia, which can halt hypoxia-driven lung maturation. We were to investigate whether the HIF-1α inducer, deferoxamine (DFX) can improve alveolarization in a rat model of bronchopulmonary dysplasia (BPD). A rat model of BPD was produced by intra-amniotic lipopolysaccharide (LPS) administration and postnatal hyperoxia (85% for 7 days), and DFX (150 mg/kg/d) or vehicle was administered to rat pups intraperitoneally for 14 days. On day 14, the rat pups were sacrificed and their lungs were removed and examined. A parallel in vitro study was performed with a human small airway epithelial cell line to test whether DFX induces the expression of HIF-1α and its target genes. Alveolarization and pulmonary vascular development were impaired in rats with BPD. However, DFX significantly ameliorated these effects. Immunohistochemical analysis showed that HIF-1α was significantly upregulated in the lungs of BPD rats treated with DFX. DFX was also found to induce HIF-1α in human small airway epithelial cells and to promote the expression of HIF-1α target genes. Our data suggest that DFX induces and activates HIF-1α, thereby improving alveolarization and vascular distribution in the lungs of rats with BPD.

Pathogenic role of HIF-1α in prostate hyperplasia in the presence of chronic inflammation.

Benign prostatic hyperplasia (BPH) commonly occurs in older men with chronic prostatitis. Although BPH is frequently accompanied by inflammation, it is unclear whether inflammation underlies prostate enlargement. Recently, we reported that hypoxia-inducible factor 1α (HIF-1α), which is known to be induced by proinflammatory cytokines, is involved in testosterone-induced prostate hyperplasia. Therefore, we hypothesized that cytokines secreted from infiltrated macrophages under inflammatory conditions stimulate prostate enlargement by up-regulating HIF-1α. In the present study, we injected lipopolysaccharide (LPS) into rat prostates to mimic prostatitis and evaluated prostate hyperplasia 14days later. Epithelial cells of LPS-treated prostates were found to be highly proliferative and HIF-1α levels in prostate tissues to be elevated. When prostate epithelial cells were incubated in conditioned medium from macrophages activated with LPS, they robustly expressed HIF-1α, and under these conditions IL-1ß, IL-6, and TNF-α cytokines were found to mediate HIF-1α induction. In addition, HIF-1α was found to enhance the expression of Twist, which initiates epithelial-mesenchymal transition (EMT). Furthermore, profound EMT features were observed in LPS-treated rat prostates, and the natural HIF-1α inhibitors ascorbate and curcumin were found to attenuate EMT and prostate hyperplasia both in vivo and in vitro. Based on these results, we propose that HIF-1α mediates prostate enlargement under inflammatory conditions, and we suggest that HIF-1α be viewed as a promising target for blocking the transition from prostatitis to BPH.

Differential roles of Sirt1 in HIF-1α and HIF-2α mediated hypoxic responses.

Hypoxia-inducible factors 1α and 2α (HIF-1α and HIF-2α) determine cancer cell fate under hypoxia. Despite the similarities of their structures, HIF-1α and HIF-2α have distinct roles in cancer growth under hypoxia, that is, HIF-1α induces growth arrest whereas HIF-2α promotes cell growth. Recently, sirtuin 1 (Sirt1) was reported to fine-tune cellular responses to hypoxia by deacetylating HIF-1α and HIF-2α. Yet, the roles of Sirt1 in HIF-1α and HIF-2α functions have been controversial. We here investigated the precise roles of Sirt1 in HIF-1α and HIF-2α regulations. Immunological analyses revealed that HIF-1α K674 and HIF-2α K741 are acetylated by PCAF and CBP, respectively, but are deacetylated commonly by Sirt1. In the Gal4 reporter systems, Sirt1 was found to repress HIF-1α activity constantly in ten cancer cell-lines but to regulate HIF-2α activity cell type-dependently. Moreover, Sirt1 determined cell growth under hypoxia depending on HIF-1α and HIF-2α. Under hypoxia, Sirt1 promoted cell proliferation of HepG2, in which Sirt1 differentially regulates HIF-1α and HIF-2α. In contrast, such an effect of Sirt1 was not shown in HCT116, in which Sirt1 inactivates both HIF-1α and HIF-2α because conflicting actions of HIF-1α and HIF-2α on cell growth may be offset. Our results provide a better understanding of the roles of Sirt1 in HIF-mediated hypoxic responses and also a basic concept for developing anticancer strategy targeting Sirt1.

Neddylation of insulin receptor substrate acts as a bona fide regulator of insulin signaling and its implications for cancer cell migration.

Irregularities in insulin signaling have significantly increased the risk of various cancers, yet the precise underlying mechanisms remain unclear. Within our study, we observed that inhibiting neddylation enhances cancer cell migration across different cancer types by activating both insulin receptor substrates 1 and 2 (IRS1 and IRS2), along with the PI3K/AKT signaling pathway. Notably, in the context of high-grade serous carcinoma (HGSC) patients, whether they had type 2 diabetes mellitus or not, IRS1 and IRS2 displayed a parallel relationship with each other while exhibiting an inverse relationship with NEDD8. We also identified C-CBL as an E3 ligase responsible for neddylating IRS1 and IRS2, with clinical evidence further confirming a reciprocal relationship between C-CBL and pAKT, thereby reinforcing the tumor suppressive role of C-CBL. Altogether, these findings suggest that neddylation genuinely participates in IRS1 and IRS2-dependent insulin signaling, effectively suppressing cancer cell migration. Thus, caution is advised when considering neddylation inhibitors as a treatment option for cancer patients, particularly those presenting with insulin signaling dysregulations linked to conditions like obesity-related type 2 diabetes or hyperinsulinemia.

Sildenafil alleviates bronchopulmonary dysplasia in neonatal rats by activating the hypoxia-inducible factor signaling pathway.

Bronchopulmonary dysplasia (BPD) is a major cause of morbidity in premature infants receiving oxygen therapy. Currently, sildenafil is being examined clinically to improve pulmonary function in patients with BPD. Based on the pharmacological action of sildenafil, the elevation of cyclic guanosine 3',5'-monophosphate (cGMP) in lung tissue is considered to underlie its beneficial effects, but this mechanism is not understood at the molecular level. Here, we examined the possibility that sildenafil helps the pulmonary system adapt to hyperoxic stress. To induce BPD, fetal rats were exposed to LPS before delivery, and neonates were exposed to hyperoxia, followed by intraperitoneal injections of sildenafil. Alveolarization was impaired in rats exposed to hyperoxia, and alveolarization significantly recovered with sildenafil. An immunohistochemical examination revealed that sildenafil effectively increased vascular distribution in lung tissue. Furthermore, the oxygen sensor hypoxia-inducible factor (HIF)-1/2α and the angiogenic factor vascular endothelial growth factor (VEGF) were highly expressed in the lungs of sildenafil-treated rats. In human small-airway epithelial cells, HIF-1/2α and its downstream genes, including VEGF, were confirmed to be induced by sildenafil at both the protein and mRNA levels. Mechanistically, cGMP in airway cells accumulated after sildenafil treatment because of interfering phosphodiesterase Type 5, and subsequently cGMP activated HIF-mediated hypoxic signaling by stimulating the phosphoinositide 3-kinase (PI3K)-v-akt murine thymoma viral oncogene homolog 1 (AKT)-mammalian target of rapamycin (mTOR) pathway. This study provides a better understanding about the mode of action for sildenafil, and suggests that HIF can be a potential target for treating patients with BPD.

Hypoxia inducible factor-1α promotes trichogenic gene expression in human dermal papilla cells.

Dermal papilla cells (DPCs) play critical roles in hair follicle development, but the underlying mechanisms that contribute to hair regeneration have yet to be fully elucidated, particularly in terms of alterations in androgenetic alopecia patients. In this study, we demonstrated that hypoxia-inducible factor-1α (HIF-1α) is suppressed in scalp tissues of androgenetic alopecia patients and potentially associated with hair follicle development. Using RT-qPCR and western blot, we found that mRNA and protein levels of trichogenic genes, LEF1 and versican (VCAN), were attenuated in HIF-1α knockdown DPCs. Under an in vivo mimicked environment in a three-dimensional spheroid culture, HIF-1α-suppressed DPCs downregulated the expression of hair induction-related genes. Finally, treatment with a HIF-1α activator resulted in the elevated expression of trichogenic genes in DPCs. This study highlights the importance of dermal HIF-1α expression in regulating trichogenic genes and provides a promising therapeutic target and a fundamental tissue engineering approach for hair loss treatment.