Akt activation promotes degradation of tuberin and FOXO3a via the proteasome

CircPGM5 regulates Foxo3a phosphorylation via MiR-21-5p/MAPK10 axis to inhibit bladder cancer progression

Bladder cancer (BC) is one of the most prevalent malignant tumors worldwide, and the incidence is especially higher in males. Extensive evidence has demonstrated the pivotal role of circular RNAs (circRNAs) in BC progression. However, the exact regulatory mechanism of circRNAs in BC remains incompletely elucidated and warrants further exploration. This study screened a novel circRNA-circPGM5 from thousands of circRNAs by high-throughput sequencing. We found that circPGM5, originating from the PGM5 gene, was significantly lower expressed in BC tissues. Quantitative real-time PCR (qRT-PCR) verified that circPGM5 showed relatively low expression in 50 pairs of BC tissues and EJ and T24 cells. Notably, circPGM5 expression was correlated with stage, grade, and lymphatic metastasis of BC. Through RNA-FISH assay, we confirmed that circPGM5 predominantly localized in the cytoplasm. Functionally, overexpression of circPGM5 inhibited the proliferation, migration, and invasion of BC cells in vitro. Remarkably, circPGM5 demonstrated markedly significant tumor growth and metastasis suppression in vivo. Mechanistically, we discovered that circPGM5 upregulated the mitogen-activated protein kinase 10 (MAPK10) expression by influencing the oncogenic miR-21-5p activity through miR-21-5p absorption. This modulation of MAPK10 impacted the phosphorylation of the tumor suppressor Foxo3a in BC. In conclusion, our findings uncovered the tumor-suppressing role of circPGM5 in BC via the miR-21-5p/MAPK10/Foxo3a axis.

Patterning, regulation, and role of FoxO/DAF-16 in the early embryo

Insulin resistance and diabetes are associated with many health issues including higher rates of birth defects and miscarriage during pregnancy. Because insulin resistance and diabetes are both associated with obesity, which also affects fertility, the role of insulin signaling itself in embryo development is not well understood. A key downstream target of the insulin/insulin-like growth factor signaling (IIS) pathway is the forkhead family transcription factor FoxO (DAF-16 in C. elegans ). Here, we used quantitative live imaging to measure the patterning of endogenously tagged FoxO/DAF-16 in the early worm embryo. In 2-4-cell stage embryos, FoxO/DAF-16 initially localized uniformly to all cell nuclei, then became dramatically enriched in germ precursor cell nuclei beginning at the 8-cell stage. This nuclear enrichment in early germ precursor cells required germ fate specification, PI3K (AGE-1)- and PTEN (DAF-18)-mediated phospholipid regulation, and the deubiquitylase USP7 (MATH-33), yet was unexpectedly insulin receptor (DAF-2)- and AKT-independent. Functional analysis revealed that FoxO/DAF-16 acts as a cell cycle pacer for early cleavage divisions-without FoxO/DAF-16 cell cycles were shorter than in controls, especially in germ lineage cells. These results reveal the germ lineage specific patterning, upstream regulation, and cell cycle role for FoxO/DAF-16 during early C. elegans embryogenesis.

Estrogen Receptor Is Required for Metformin-Induced Apoptosis in Breast Cancer Cells Under Hyperglycemic Conditions

Backgrounds

About 25% to 30% of estrogen receptor (ER)-positive breast cancer patients develop resistance to endocrine therapy. Human epidermal growth factor receptor 2 (HER2) has been shown to cooperate with several growth factors that regulate cellular energy metabolism, including the insulin-like growth factor 1 receptor (IGF-1R).

Objective

As the first-line therapy for type 2 diabetes mellitus (T2DM) patients, metformin is widely known to inhibit the metabolic reprogramming of cancer cells. This study aims to investigate metformin's efficacy in inhibiting endocrine resistance related to genes regulating energy metabolism in both ER-positive and ER-negative breast cancer cell lines under hyperglycemic conditions.

Design and methods

MDA-MB-361 (ER-positive, HER2-positive) and SKBR3 (ER-negative, HER2-positive) cancer cell lines were used to represent ER status. Cell viability and cell survival rate were measured using the colorimetric assay of Cell Counting Kit-8. All mRNA levels were quantified using real-time quantitative polymerase chain reaction preceded by reverse transcription. A P value of <.05 was considered statistically significant.

Results

Unlike MDA-MB-361, SKBR3 were found to acquire resistance upon metformin treatment in hyperglycemic conditions. Moreover, the mRNA expression of IGF-1R and its downstream signaling, such as the mammalian target of rapamycin (mTOR), was not affected by metformin. Meanwhile, the mRNA expression level of ribosomal S6 kinase 1 (S6K1) was upregulated, whereas forkhead box O1 (FOXO1) was downregulated after metformin treatment in hyperglycemic conditions.

Conclusions

This preliminary study suggests that an alternative pathway of metformin resistance may exist in the absence of ERα. Therefore, relying solely on metformin may be inadequate to inhibit the aggressiveness of breast cancer cells.

Spinal sirtuin 2 attenuates bone cancer pain by deacetylating FoxO3a

Bone cancer pain (BCP) is refractory to currently used analgesics. Recently, sirtuin 2 (SIRT2) was reported to play a vital role in neuropathic pain but its role in BCP remains unknown. It was hypothesized that spinal SIRT2 attenuates BCP by deacetylating FoxO3a and suppressing oxidative stress. The mouse model of BCP established by injecting tumor cells into the intramedullary space of the femur demonstrated that spinal SIRT2 and FoxO3a were downregulated in BCP development. Intrathecal administration of LV-SIRT2 reduced pain hypersensitivity (mechanical and thermal nociception) in BCP mice. Spinal SIRT2 overexpression upregulated FoxO3a and antioxidant genes (SOD2 and catalase) and inhibited FoxO3a acetylation, phosphorylation, and ubiquitination. Moreover, intrathecal administration of SIRT2 shRNA induced pain hypersensitivity in normal mice. Spinal SIRT2 knockdown downregulated FoxO3a and antioxidant genes and increased FoxO3a acetylation, phosphorylation, and ubiquitination. In summary, spinal SIRT2 increases FoxO3a expression in BCP mice and inhibits oxidative stress by deacetylating FoxO3a and further reducing FoxO3a phosphorylation, ubiquitination, and degradation, leading to BCP relief.

Helicobacter pylori CagA protein induces gastric cancer stem cell-like properties through the Akt/FOXO3a axis

The presence of Helicobacter pylori (H. pylori) infection poses a substantial risk for the development of gastric adenocarcinoma. The primary mechanism through which H. pylori exerts its bacterial virulence is the cytotoxin CagA. This cytotoxin has the potential to induce inter-epithelial mesenchymal transition, proliferation, metastasis, and the acquisition of stem cell-like properties in gastric cancer (GC) cells infected with CagA-positive H. pylori. Cancer stem cells (CSCs) represent a distinct population of cells capable of self-renewal and generating heterogeneous tumor cells. Despite evidence showing that CagA can induce CSCs-like characteristics in GC cells, the precise mechanism through which CagA triggers the development of GC stem cells (GCSCs) remains uncertain. This study reveals that CagA-positive GC cells infected with H. pylori exhibit CSCs-like properties, such as heightened expression of CD44, a specific surface marker for CSCs, and increased ability to form tumor spheroids. Furthermore, we have observed that H. pylori activates the PI3K/Akt signaling pathway in a CagA-dependent manner, and our findings suggest that this activation is associated with the CSCs-like characteristics induced by H. pylori. The cytotoxin CagA, which is released during H. pylori infection, triggers the activation of the PI3K/Akt signaling pathway in a CagA-dependent manner. Additionally, CagA inhibits the transcription of FOXO3a and relocates it from the nucleus to the cytoplasm by activating the PI3K/Akt pathway. Furthermore, the regulatory function of the Akt/FOXO3a axis in the transformation of GC cells into a stemness state was successfully demonstrated.

Prolyl isomerase Pin1 promotes autophagy and cancer cell viability through activating FoxO3 signalling

Pin1-directed prolyl isomerization is a central common oncogenic mechanism to drive tumorigenic processes. However, the role of Pin1 in cellular autophagy is still poorly understood. Here we report that pharmacological inhibition of Pin1 decreased the formation of autophagosome/autolysosomes upon nutrient starvation. Inhibition of Pin1 reduced, whereas forced expression of Pin1 increased, the level of LC3 and viability of U2OS and PANC-1 cells. Pin1 could augment the accumulation of LC3 upon chloroquine treatment, while chloroquine also disturbed its function on cell viability. RNA-Seq and qPCR identified altered autophagic pathway upon Pin1 silencing. Mechanistically, FoxO3 was identified critical for Pin1-mediated autophagy. Knockdown of FoxO3 could rescue the changes of LC3 level and cellular viability caused by Pin1 overexpression. In xenograft mouse model, Pin1 reduced the sensitivity of PANC-1 to chloroquine while FoxO3 silencing could inhibit Pin1's function. Moreover, Pin1 could bind FoxO3 via its pS284-P motif, reduce its phosphorylation at T32, facilitate its nuclear retention, and therefore increased its transcriptional activity. S284A mutation of FoxO3 interfered with its T32 phosphorylation, reduced its nuclear localization and disrupted its function to support cell viability upon nutrient starvation. Furthermore, the protein level of Pin1 positively correlated with FoxO3 nuclear localization and LC3 level in pancreatic adenocarcinoma and osteosarcoma samples. Together, this study highlights an important role for Pin1-FoxO3 axis in regulating autophagy and cancer cell viability. Intervening in the Pin1-FoxO3 interaction would serve as an effective therapeutic strategy and the pS284-P motif of FoxO3 provides a potential target for drug design.

IKBKE regulates angiogenesis by modulating VEGF expression and secretion in glioblastoma

PURPOSE

As a noncanonical inflammatory kinase, IKBKE is frequently overexpressed and activated and has been identified as an oncogenic protein in glioblastoma. However, the potential function and underlying mechanism of IKBKE contributing to tumor angiogenesis remain elusive.

METHODS

First, we analyzed the correlation between IKBKE and VEGF expression in glioma samples by immunohistochemistry (IHC). Second, HUVEC-related assays and Western blot were used to detect the regulatory effect of IKBKE on angiogenesis by modulating VEGF expression. Third, IKBKE depletion could alleviate the influence of VEGF expression on IHC of intracranial glioma model.

RESULTS

We demonstrate that depletion of IKBKE markedly inhibits tumor growth and angiogenesis in glioblastoma. Mechanistically, IKBKE induces VEGF expression and secretion by regulating AKT/FOXO3a in glioblastoma.

CONCLUSIONS

This study reveals that IKBKE is a novel oncogenic molecule that induces angiogenesis through the promotion of VEGF expression and highlights the potential of targeting IKBKE for glioblastoma therapy.

microRNA-96 targets the INS/AKT/GLUT4 signaling axis: Association with and effect on diabetic retinopathy

Background

miR-96-5p is a highly expressed microRNA in the retina of subjects with diabetes. The INS/AKT/GLUT4 signaling axis is the main cell signaling pathway of glucose uptake in cells. Here, we investigated the role of miR-96-5p in this signaling pathway.

Methods

Expression levels of miR-96-5p and its target genes were measured under high glucose conditions, in the retina of streptozotocin-induced diabetic mice, in the retina of AAV-2-eGFP-miR-96 or GFP intravitreal injected mice and in the retina of human donors with diabetic retinopathy (DR). MTT, wound healing, tube formation, Western blot, TUNEL, angiogenesis assays and hematoxylin-eosin staining of the retinal sections were performed.

Results

miR-96-5p expression was increased under high glucose conditions in mouse retinal pigment epithelial (mRPE) cells, in the retina of mice receiving AAV-2 carrying miR-96 and STZ-treated mice. Expression of the miR-96-5p target genes related to the INS/AKT/GLUT4 signaling pathway was reduced following miR-96-5p overexpression. mmu-miR-96-5p expression decreased cell proliferation and thicknesses of retinal layers. Cell migration, tube formation, vascular length, angiogenesis, and TUNEL-positive cells were increased.

Conclusions

In in vitro and in vivo studies and in human retinal tissues, miR-96-5p regulated the expression of the PIK3R1, PRKCE, AKT1, AKT2, and AKT3 genes in the INS/AKT axis and some genes involved in GLUT4 trafficking, such as Pak1, Snap23, RAB2a, and Ehd1. Because disruption of the INS/AKT/GLUT4 signaling axis causes advanced glycation end product accumulation and inflammatory responses, the inhibition of miR-96-5p expression could ameliorate DR.

Tumor-derived extracellular vesicles delivering TNF-α promotes colorectal cancer metastasis via the NF-kB/LAMB3/AKT axis by targeting SNAP23

Accumulating evidence have demonstrated that cytokines are enriched in tumor-derived extracellular vesicles (EVs) and widely involved in tumorigenesis of various types of carcinomas, including colorectal cancer (CRC). Nevertheless, the functions of cytokines in EVs secreted from colorectal cancer cells remain largely unknown. In the present study, we found that TNF-α was elevated in EVs from CRC patient serum samples and CRC cell lines, of which the expression was associated with aggressive features of colorectal cancer. EV TNF-α secretion is dependent on synaptosome-associated protein 23 (SNAP23). Functional experiments revealed that EV TNF-α promotes CRC cell metastasis via the NF-κB pathway by targeting SNAP23. Mechanistically, SNAP23 was transcriptionally upregulated by EV TNF-α/NF-κB axis to enhance the expression of laminin subunit beta-3 (LAMB3), thereby activating the PI3K/AKT signaling pathway and consequently facilitate CRC progression. Based on our findings, we could conclude that EV TNF-α plays an oncogenic role in CRC progression through SNAP23, which in turn promotes EV TNF-α secretion, suggesting that EV TNF-α/SNAP23 axis may serve as a diagnostic biomarker and potential therapeutic target for CRC.

Human Milk Exosomes Induce ZO-1 Expression via Inhibition of REDD1 Expression in Human Intestinal Epithelial Cells

Human milk exosomes (HMEs) enhance intestinal barrier function and contribute to an improvement in inflammation and mucosal injury, such as necrotizing enteritis (NEC), in infants. Here, we aimed to elucidate the intracellular factors involved in HME-induced expression of zonula occludens-1 (ZO-1), a tight junction protein, in Caco-2 human intestinal epithelial cells. HME treatment for 72 h significantly increased transepithelial electrical resistance in these cells. The mean ZO-1 protein levels in cells treated with HME for 72 h were significantly higher than those in the control cells. The mRNA and protein levels of regulated in development and DNA damage response 1 (REDD1) in HME-treated cells were significantly lower than those in the control cells. Although HME treatment did not increase the mechanistic target of rapamycin (mTOR) level in Caco-2 cells, it significantly increased the phosphorylated mTOR (p-mTOR) level and p-mTOR/mTOR ratio. The ZO-1 protein levels in cells treated with an inducer of REDD1, cobalt chloride (CoCl₂) alone were significantly lower than those in the control cells. However, ZO-1 protein levels in cells co-treated with HME and CoCl₂ were significantly higher than those in cells treated with CoCl₂ alone. Additionally, REDD1 protein levels in cells treated with CoCl₂ alone were significantly higher than those in the control cells. However, REDD1 protein levels in cells co-treated with HME and CoCl₂ were significantly lower than those in cells treated with CoCl₂ alone. This HME-mediated effect may contribute to the development of barrier function in the infant intestine and protect infants from diseases.

Negative regulator NLRC3: Its potential role and regulatory mechanism in immune response and immune-related diseases

NLRC3 is a member of the pattern recognition receptors nucleotide-binding oligomerization domain (NOD)-like receptors (NLRs) family, and plays a pivotal regulatory role in modulating the activation of immune cells. In macrophages, NLRC3 inhibits the activation of the NF-κB signaling pathway, the STING/TBK1 signaling pathway, and the formation of the inflammasome. In the context of T cells immune response, NLRC3 prevents the activation of T cells by regulating the function of dendritic cells and directly influencing the function of T cells. Different from other pattern recognition receptors, NLRC3 is more closely associated with regulatory activity than pathogens recognition, it influences the fates of cells, for example, prevents proliferation, promotes apoptosis and inhibits pyroptosis. These cellular functions regulated by NLRC3 are involved in the development processes of a variety of diseases, such as infectious disease, sterile inflammatory diseases, and cancer. However, its characteristics, function and regulatory mechanism in immune response and immune-related diseases have not been addressed fully. In this review, we elaborate the potential roles of NLRC3 from several different levels, include molecular mechanism, cellular functions in the immune-related diseases.

mTORC1 Activity in Psoriatic Lesions Is Mediated by Aberrant Regulation through the Tuberous Sclerosis Complex

In the basal, proliferative layer of healthy skin, the mTOR complex 1 (mTORC1) is activated, thus regulating proliferation while preventing differentiation. When cells leave the proliferative, basal compartment, mTORC1 signaling is turned off, which allows differentiation. Under inflammatory conditions, this switch is hijacked by cytokines and prevents proper differentiation. It is currently unknown how mTORC1 is regulated to mediate these effects on keratinocyte differentiation. In other tissues, mTORC1 activity is controlled through various pathways via the tuberous sclerosis complex (TSC). Thus, we investigated whether the TS complex is regulated by proinflammatory cytokines and contributes to the pathogenesis of psoriasis. TNF-α as well as IL-1β induced the phosphorylation of TSC2, especially on S939 via the PI3-K/AKT and MAPK pathway. Surprisingly, increased TSC2 phosphorylation could not be detected in psoriasis patients. Instead, TSC2 was strongly downregulated in lesional psoriatic skin compared to non-lesional skin of the same patients or healthy skin. In vitro inflammatory cytokines induced dissociation of TSC2 from the lysosome, followed by destabilization of the TS complex and degradation. Thus, we assume that in psoriasis, inflammatory cytokines induce strong TSC2 phosphorylation, which in turn leads to its degradation. Consequently, chronic mTORC1 activity impairs ordered keratinocyte differentiation and contributes to the phenotypical changes seen in the psoriatic epidermis.

Polymeric immunoglobulin receptor suppresses colorectal cancer through the AKT-FOXO3/4 axis by downregulating LAMB3 expression

Colorectal cancer (CRC) remains one of the most common malignancies worldwide and its mechanism is unclear. Polymeric immunoglobulin receptor (PIGR) which plays an important role in mucosal immunity is widely expressed in the mucosal epithelium and is dysregulated in different tumors. However, the role and underlying mechanisms of PIGR in CRC remain unclear. Here, we demonstrated that PIGR was hypermethylated and downregulated in our cohort (N = 272), and these features were associated with reduced overall survival in patients (HRmethylation 1.61, 95% CI [1.11-2.33]). These findings were validated by external TCGA and GEO data. Moreover, PIGR overexpression inhibits CRC cell malignant phenotypes in vitro and impedes CRC cells growth in male BALB/c nude mice. Mechanistically, PIGR physically associates with RE1 silencing transcription factor (REST) and blocks the transcription of laminin subunit beta 3 (LAMB3). Subsequently, the AKT-FOXO3/4 axis was suppressed by downregulated LAMB3. In the drug sensitive assay, PIGR-overexpressing cells were more sensitive to cisplatin and gemcitabine. Together, PIGR may serve as a powerful prognostic biomarker and putative tumor suppressor by suppressing the AKT-FOXO3/4 axis by downregulating LAMB3 in CRC. Our study may offer a novel therapeutic strategy for treating CRC patients who highly express PIGR with cisplatin and gemcitabine.

Amino acid metabolism: challenges and opportunities for the therapeutic treatment of leukemia and lymphoma

Leukemia and lymphoma-the most common hematological malignant diseases-are often accompanied by complications such as drug resistance, refractory diseases and relapse. Amino acids (AAs) are important energy sources for malignant cells. Tumor-mediated AA metabolism is associated with the immunosuppressive properties of the tumor microenvironment, thereby assisting malignant cells to evade immune surveillance. Targeting abnormal AA metabolism in the tumor microenvironment may be an effective therapeutic approach to address the therapeutic challenges of leukemia and lymphoma. Here, we review the effects of glutamine, arginine and tryptophan metabolism on tumorigenesis and immunomodulation, and define the differences between tumor cells and immune effector cells. We also comment on treatments targeting these AA metabolism pathways in lymphoma and leukemia and discuss how these treatments have profound adverse effects on tumor cells, but leave the immune cells unaffected or mildly affected.

SIRT1-mediated deacetylation of FOXO3a transcription factor supports pro-angiogenic activity of interferon-deficient tumor-associated neutrophils

Angiogenesis plays an important role during tumor growth and metastasis. We could previously show that Type I interferon (IFN)-deficient tumor-associated neutrophils (TANs) show strong pro-angiogenic activity, and stimulate tumor angiogenesis and growth. However, the exact mechanism responsible for their pro-angiogenic shift is not clear. Here, we set out to delineate the molecular mechanism and factors regulating pro-angiogenic properties of neutrophils in the context of Type I IFN availability. We demonstrate that neutrophils from IFN-deficient (Ifnar1^-/- ) mice efficiently release pro-angiogenic factors, such as VEGF, MMP9 or BV8, and thus significantly support the vascular normalization of tumors by increasing the maturation of perivascular cells. Mechanistically, we could show here that the expression of pro-angiogenic factors in neutrophils is controlled by the transcription factor forkhead box protein O3a (FOXO3a), which activity depends on its post-translational modifications, such as deacetylation or phosphorylation. In TANs isolated from Ifnar1^-/- mice, we observe significantly elevated SIRT1, resulting in SIRT1-mediated deacetylation of FOXO3a, its nuclear retention and activation. Activated FOXO3a supports in turn the transcription of pro-angiogenic genes in TANs. In the absence of SIRT1, or after its inhibition in neutrophils, elevated kinase MEK/ERK and PI3K/AKT activity is observed, leading to FOXO3a phosphorylation, cytoplasmic transfer and inactivation. In summary, we have found that FOXO3a is a key transcription factor controlling the angiogenic switch of neutrophils. Post-translational FOXO3a modifications regulate its transcriptional activity and, as a result, the expression of pro-angiogenic factors supporting development of vascular network in growing tumors. Therefore, targeting FOXO3a activity could provide a novel strategy of antiangiogenic targeted therapy for cancer.

Clinical and Tumor Characteristics of Patients with High Serum Levels of Growth Differentiation Factor 15 in Advanced Pancreatic Cancer

Simple Summary

Growth differentiation factor 15 (GDF-15) is a stress responsive cytokine that mediates food intake, energy consumption, and body weight. We aimed to evaluate whether circulating GDF-15 level could be associated with cachexia symptoms, which include loss of skeletal muscle mass, systemic inflammatory reaction, poor performance status, anorexia, shortened survival time and biological tumor activity in advanced pancreatic cancer (APC). The cut-off for serum GDF-15 was 3356.6 pg/mL, as the mean plus two standard deviations in patients with benign pancreatic disease. APC patients with high serum GDF-15 showed worsened performance, anorexia and elevations of inflammatory and tumor burden, signatures of cachexia, and activation of Akt and JNK in tumor GDF-15-producing pathways. This study identified tumor-driven GDF-15 as a potential cause of cachexia symptoms in APC.

Abstract

We aimed to evaluate the association of circulating growth differentiation factor 15 (GDF-15) with cachexia symptoms and the biological activity of advanced pancreatic cancer (APC). Treatment-naïve patients with liver metastasis of APC or with benign pancreatic disease were retrospectively analyzed. Clinical data, blood samples, and biopsy specimens of liver metastasis were collected prior to anti-cancer treatment. Serum GDF-15 levels and multiple protein expressions in lysates extracted from liver metastasis were measured by enzyme-linked immuno-sorbent assay and reverse-phase protein array, respectively. The cut-off for serum GDF-15 was determined as 3356.6 pg/mL, the mean plus two standard deviations for benign pancreatic disease. The high-GDF-15 group was characterized as showing low Karnofsky performance status (KPS) (p = 0.037), poor Eastern Cooperative Oncology Group performance status (ECOG-PS) (p = 0.049), severe appetite loss (p = 0.011), and high serum levels of carbohydrate antigen 19-9 (p = 0.019) and C-reactive protein (p = 0.009). Tumors of the high-GDF-15 group expressed high levels of phosphorylated (p)JNK (p = 0.007) and pAkt (p = 0.040). APC patients with high serum GDF-15 showed signatures of cachexia and activation of the signaling pathways involving Akt and JNK in the tumor. This study indicated circulating GDF-15 could be associated with cachectic symptoms in APC.

Ubiquitin-specific protease 7 mediates platelet-derived growth factor-induced pulmonary arterial smooth muscle cells proliferation

Pulmonary arterial hypertension is a devastating pulmonary vascular disease, in which the pathogenesis is complicated and unclear. Pulmonary arterial smooth muscle cells (PASMCs) proliferation is a key pathological feature of pulmonary arterial hypertension. It has been shown that ubiquitin-specific protease 7 (USP7) is involved in cancer cell proliferation via deubiquitinating and stabilizing E3 ubiquitin ligase mouse double minute 2 (MDM2). However, the effect of USP7 and MDM2 on platelet-derived growth factor (PDGF)-induced PASMCs proliferation is uncertain. This study aims to explore this issue. Our results indicated that PDGF up-regulated USP7 protein expression and stimulated PASMCs proliferation; this was accompanied with the increase of MDM2, forkhead box O4 (FoxO4) reduction and elevation of CyclinD1. While prior transfection of USP7 siRNA blocked PDGF-induced MDM2 up-regulation, FoxO4 down-regulation, increase of CyclinD1 and cell proliferation. Pre-depletion of MDM2 by siRNA transfection reversed PDGF-induced reduction of FoxO4, up-regulation of CyclinD1 and PASMCs proliferation. Furthermore, pre-treatment of cells with proteasome inhibitor MG-132 also abolished PDGF-induced FoxO4 reduction, CyclinD1 elevation and cell proliferation. Our study suggests that USP7 up-regulates MDM2, which facilitates FoxO4 ubiquitinated degradation, and subsequently increases the expression of CyclinD1 to mediate PDGF-induced PASMCs proliferation.

Targeting Akt in cancer for precision therapy

Biomarkers-guided precision therapeutics has revolutionized the clinical development and administration of molecular-targeted anticancer agents. Tailored precision cancer therapy exhibits better response rate compared to unselective treatment. Protein kinases have critical roles in cell signaling, metabolism, proliferation, survival and migration. Aberrant activation of protein kinases is critical for tumor growth and progression. Hence, protein kinases are key targets for molecular targeted cancer therapy. The serine/threonine kinase Akt is frequently activated in various types of cancer. Activation of Akt promotes tumor progression and drug resistance. Since the first Akt inhibitor was reported in 2000, many Akt inhibitors have been developed and evaluated in either early or late stage of clinical trials, which take advantage of liquid biopsy and genomic or molecular profiling to realize personalized cancer therapy. Two inhibitors, capivasertib and ipatasertib, are being tested in phase III clinical trials for cancer therapy. Here, we highlight recent progress of Akt signaling pathway, review the up-to-date data from clinical studies of Akt inhibitors and discuss the potential biomarkers that may help personalized treatment of cancer with Akt inhibitors. In addition, we also discuss how Akt may confer the vulnerability of cancer cells to some kinds of anticancer agents.

Stromal Cell-Contact Dependent PI3K and APRIL Induced NF-κB Signaling Prevent Mitochondrial- and ER Stress Induced Death of Memory Plasma Cells

The persistence of long-lived memory plasma cells in the bone marrow depends on survival factors available in the bone marrow, which are provided in niches organized by stromal cells. Using an ex vivo system in which we supply the known survival signals, direct cell contact to stromal cells, and the soluble cytokine a proliferation-inducing ligand (APRIL), we have elucidated the critical signaling pathways required for the survival of long-lived plasma cells. Integrin-mediated contact of bone marrow plasma cells with stromal cells activates the phosphatidylinositol 3-kinase (PI3K) signaling pathway, leading to critical inactivation of Forkhead-Box-Protein O1/3 (FoxO1/3) and preventing the activation of mitochondrial stress-associated effector caspases 3 and 7. Accordingly, inhibition of PI3K signaling in vivo ablates bone marrow plasma cells. APRIL signaling, by the nuclear factor κB (NF-κB) pathway, blocks activation of the endoplasmic-reticulum-stress-associated initiator caspase 12. Thus, stromal-cell-contact-induced PI3K and APRIL-induced NF-κB signaling provide the necessary and complementary signals to maintain bone marrow memory plasma cells.

Acetylshikonin Induces Apoptosis in Human Colorectal Cancer HCT-15 and LoVo Cells via Nuclear Translocation of FOXO3 and ROS Level Elevation

Acetylshikonin, a naphthoquinone, is a pigment compound derived from Arnebia sp., which is known for its anti-inflammatory potential. However, its anticarcinogenic effect has not been well investigated. Thus, in this study, we focused on investigating its apoptotic effects against HCT-15 and LoVo cells, which are human colorectal cancer cells. MTT assay, cell counting assay, and colony formation assay have shown acetylshikonin treatment induced cytotoxic and antiproliferative effects against colorectal cancer cells in a dose- and time-dependent manner. DNA fragmentation was observed via terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay. Also, the increase of subG1 phase in cell cycle arrest assay and early/late apoptotic rates in annexin V/propidium iodide (PI) double staining assay was observed, which indicates an apoptotic potential of acetylshikonin against colorectal cancer cells. 2′,7′-Dichlorofluorescin diacetate (DCF-DA) staining was used to evaluate reactive oxygen species (ROS) generation in acetylshikonin-treated colorectal cancer cells. Fluorescence-activated cell sorting (FACS) analysis showed that acetylshikonin induced an increase in reactive oxygen species (ROS) levels and apoptotic rate in a dose- and time-dependent manner in HCT-15 and LoVo cells. In contrast, cotreatment with N-acetyl cysteine (NAC) has reduced ROS generation and antiproliferative effects in colorectal cancer cells. Western blotting analysis showed that acetylshikonin treatment induced increase of cleaved PARP, γH2AX, FOXO3, Bax, Bim, Bad, p21, p27, and active forms of caspase-3, caspase-7, caspase-9, caspase-6, and caspase-8 protein levels, while those of inactive forms were decreased. Also, the expressions of pAkt, Bcl-2, Bcl-xL, peroxiredoxin, and thioredoxin 1 were decreased. Furthermore, western blotting analysis of cytoplasmic and nuclear fractionated proteins showed that acetylshikonin treatment induced the nuclear translocation of FOXO3, which might result from DNA damage by the increased intracellular ROS level. This study represents apoptotic potential of acetylshikonin against colorectal cancer cells via translocation of FOXO3 to the nucleus and upregulation of ROS generation.

Role of TSC1 in physiology and diseases

Since its initial discovery as the gene altered in Tuberous Sclerosis Complex (TSC), an autosomal dominant disorder, the interest in TSC1 (Tuberous Sclerosis Complex 1) has steadily risen. TSC1, an essential component of the pro-survival PI3K/AKT/MTOR signaling pathway, plays an important role in processes like development, cell growth and proliferation, survival, autophagy and cilia development by co-operating with a variety of regulatory molecules. Recent studies have emphasized the tumor suppressive role of TSC1 in several human cancers including liver, lung, bladder, breast, ovarian, and pancreatic cancers. TSC1 perceives inputs from various signaling pathways, including TNF-α/IKK-β, TGF-β-Smad2/3, AKT/Foxo/Bim, Wnt/β-catenin/Notch, and MTOR/Mdm2/p53 axis, thereby regulating cancer cell proliferation, metabolism, migration, invasion, and immune regulation. This review provides a first comprehensive evaluation of TSC1 and illuminates its diverse functions apart from its involvement in TSC genetic disorder. Further, we have summarized the physiological functions of TSC1 in various cellular events and conditions whose dysregulation may lead to several pathological manifestations including cancer.

Methionine controls insulin/mammalian target of rapamycin complex 1 activity by modulating tuberous sclerosis complex 2 stability

Tuberous sclerosis complex 2 (TSC2) is a tumor-suppressor protein that is partially regulated by insulin, energy, oxygen, and growth factors. Mutations in the TSC2 gene and loss of TSC2 promote cell growth by the mammalian target of rapamycin complex 1 (mTORC1) activation. Furthermore, S-adenosylmethionine (SAM) sensor upstream of mTORC1 indirectly inhibits mTORC1 activity via the methionine metabolite SAM. Here, we investigated the effects of methionine on insulin/TSC2/mTORC1 activity. Our results showed that methionine affected TSC2 stability and abolished TSC2 localization to the lysosome. Moreover, activation of insulin signaling contributed to TSC2 degradation in a methionine deprivation-dependent manner. Thus, methionine and insulin crosstalk occurred via TSC2.

Role of Forkhead box O3a transcription factor in autoimmune diseases

Forkhead box O3a (FOXO3a) transcription factor, the most important member of Forkhead box O family, is closely related to cell proliferation, apoptosis, autophagy, oxidative stress and aging. The downregulation of FOXO3a has been verified to be associated with the poor prognosis, severer malignancy and chemoresistance in several human cancers. The activity of FOXO3a mainly regulated by phosphorylation of protein kinase B. FOXO3a plays a vital role in promoting the apoptosis of immune cells. FOXO3a could also modulate the activation, differentiation and function of T cells, regulate the proliferation and function of B cells, and mediate dendritic cells tolerance and immunity. FOXO3a accommodates the immune response through targeting nuclear factor kappa-B and FOXP3, as well as regulating the expression of cytokines. Besides, FOXO3a participates in intercellular interactions. FOXO3a inhibits dendritic cells from producing interleukin-6, which inhibits B-cell lymphoma-2 (BCL-2) and BCL-XL expression, thereby sparing resting T cells from apoptosis and increasing the survival of antigen-stimulated T cells. Recently, plentiful evidences further illustrated the significance of FOXO3a in the pathogenesis of autoimmune diseases, including systemic lupus erythematosus, rheumatoid arthritis, inflammatory bowel disease, ankylosing spondylitis, myositis, multiple sclerosis, and systemic sclerosis. In this review, we focused on the biological function of FOXO3a and related signaling pathways regarding immune system, and summarized the potential role of FOXO3a in the pathogenesis, progress and therapeutic potential of autoimmune diseases.

Stability of tuberous sclerosis complex 2 is controlled by methylation at R1457 and R1459

Mutations in genes that encode components of tuberous sclerosis complex 2 (TSC2) are associated with tuberous sclerosis complex disease. TSC2 interacts with tuberous sclerosis complex 1 to form a complex that negatively regulates cell growth and proliferation via the inactivation of mechanistic target of rapamycin complex 1. The activity of TSC2 is mainly regulated via posttranslational modifications such as phosphorylation. However, the control of TSC2 activity is not entirely achieved by phosphorylation. In this study, we show that TSC2 is methylated at R1457 and R1459 by protein arginine methyltransferase 1 (PRMT1). Methylation of these two residues can affect the phosphorylation status through protein kinase B (Akt) of TSC2 at T1462 and is essential for TSC2 stability. Taken together, these findings indicate that novel posttranslational modifications are important for the regulation of TSC2 stability through PRMT1-mediated methylation.

Carfilzomib inhibits the growth of lung adenocarcinoma via upregulation of Gadd45a expression

Proteasome inhibitors have shown remarkable success in the treatment of hematologic neoplasm. There has been a lot of attention to applying these drugs for solid tumor treatment. Recent preclinical study has signified the effectiveness on cell proliferation inhibition in lung adenocarcinoma treated by carfilzomib (CFZ), a second generation proteasome inhibitor. However, no insight has been gained regarding the mechanism. In this study, we have systematically investigated the CFZ functions in cell proliferation and growth, cell cycle arrest, and apoptosis in lung adenocarcinoma cells. Flow cytometry experiments showed that CFZ significantly induced G2/M cell cycle arrest and apoptosis in lung adenocarcinoma. MTS and colony formation assays revealed that CFZ substantially inhibited survival of lung adenocarcinoma cells. All results were consistently correlated to the upregulation expression of Gadd45a, which is an important gene in modulating cell cycle arrest and apoptosis in response to physiologic and environmental stresses. Here, upregulation of Gadd45a expression was observed after CFZ treatment. Knocking down Gadd45a expression suppressed G2/M arrest and apoptosis in CFZ-treated cells, and reduced cytotoxicity of this drug. The protein expression analysis has further identified that the AKT/FOXO3a pathway is involved in Gadd45a upregulation after CFZ treatment. These findings unveil a novel mechanism of proteasome inhibitor in anti-solid tumor activity, and shed light on novel preferable therapeutic strategy for lung adenocarcinoma. We believe that Gadd45a expression can be a highly promising candidate predictor in evaluating the efficacy of proteasome inhibitors in solid tumor therapy.

The Rag GTPase Regulates the Dynamic Behavior of TSC Downstream of Both Amino Acid and Growth Factor Restriction

The dysregulation of the metabolic regulator TOR complex I (TORC1) contributes to a wide array of human pathologies. Tuberous sclerosis complex (TSC) is a potent inhibitor of TORC1. Here, we demonstrate that the Rag GTPase acts in both the amino-acid-sensing and growth factor signaling pathways to control TORC1 activity through the regulation of TSC dynamics in HeLa cells and Drosophila. We find that TSC lysosomal-cytosolic exchange increases in response to both amino acid and growth factor restriction. Moreover, the rate of exchange mirrors TSC function, with depletions of the Rag GTPase blocking TSC lysosomal mobility and rescuing TORC1 activity. Finally, we show that the GATOR2 complex controls the phosphorylation of TSC2, which is essential for TSC exchange. Our data support the model that the amino acid and growth factor signaling pathways converge on the Rag GTPase to inhibit TORC1 activity through the regulation of TSC dynamics.

Expression Regulation and Physiological Role of Transcription Factor FOXO3a During Ovarian Follicular Development

In mammals, developing ovarian follicles transform from primordial follicles to primary follicles, secondary follicles, and mature follicles, accompanied by changes in follicular secretory functions. FoxO3a is a member of the forkhead transcription factor family (FoxO), which plays an important role in the cell cycle, DNA damage repair, apoptosis, oxidative stress, and energy metabolism. Recent studies have shown that FOXO3a is involved in the physiological regulation of follicular development and pathological progression of related ovarian diseases, which will provide useful concepts and strategies for retarding ovarian aging, prolonging the ovarian life span, and treating ovarian diseases. Therefore, the regulation of FOXO3a expression, as well as the physiological contribution during ovarian follicular development are detailed in this paper, presenting an important reference for the further study of ovarian biology.

Activation of forkhead box O3a by mono(2-ethylhexyl)phthalate and its role in protection against mono(2-ethylhexyl)phthalate-induced oxidative stress and apoptosis in human cardiomyocytes

Mono(2-ethylhexyl)phthalate (MEHP), the active metabolite of di(2-ethylhexyl)phthalate (DEHP), is known to exert cardiotoxicity. The aim of the present study was to investigate the role of forkhead box O3a (FOXO3a) in MEHP-induced human AC16 cardiomyocyte injuries. MEHP reduced cell viability and mitochondrial membrane potential (ΔΨm), whereas it increased lactate dehydrogenase (LDH) leakage, production of reactive oxygen species (ROS), and apoptosis in cardiomyocytes. The expression of FOXO3a and its target genes, mitochondrial superoxide dismutase (Mn-SOD) and apoptosis repressor with caspase recruitment domain (ARC), increased after MEHP exposure, but the expression of p-FOXO3a protein was decreased. Overexpression of FOXO3a decreased the production of ROS and the apoptosis rate induced by MEHP, and the expression of Mn-SOD and ARC was further increased after MEHP exposure. In contrast, knockdown of FOXO3a resulted in increased ROS production and apoptosis and suppressed the expression of Mn-SOD and ARC in the presence of MEHP. However, overexpression or knockdown of FOXO3a did not affect MEHP-induced loss of ΔΨm. In conclusion, the loss of ΔΨm and apoptosis are involved in MEHP-induced cardiomyocyte toxicity. Activation of FOXO3a defends against MEHP-induced oxidative stress and apoptosis by upregulating the expression of Mn-SOD and ARC in AC16 cardiomyocytes.

Comparison of miRNA Expression Profiles between HIV-1 and HIV-2 Infected Monocyte-Derived Macrophages (MDMs) and Peripheral Blood Mononuclear Cells (PBMCs)

During the progression of HIV-1 infection, macrophage tropic HIV-1 that use the CCR5 co-receptor undergoes a change in co-receptor use to CXCR4 that is predominately T cell tropic. This change in co-receptor preference makes the virus able to infect T cells. HIV-2 is known to infect MDMs and T cells and is dual tropic. The aim of this study was to elucidate the differential expression profiles of host miRNAs and their role in cells infected with HIV-1/HIV-2. To achieve this goal, a comparative global miRNA expression profile was determined in human PBMCs and MDMs infected with HIV-1/HIV-2. Differentially expressed miRNAs were identified in HIV-1/HIV-2 infected PBMCs and MDMs using the next-generation sequencing (NGS) technique. A comparative global miRNA expression profile in infected MDMs and PBMCs with HIV-1 and HIV-2 identified differential expression of several host miRNAs. These differentially expressed miRNAs are likely to be involved in many signaling pathways, like the p53 signaling pathway, PI3K-Akt signaling pathways, MAPK signaling pathways, FoxO signaling pathway, and viral carcinogenesis. Thus, a comparative study of the differential expression of host miRNAs in MDMs and T cell in response to HIV-1 and HIV-2 infection will help us to identify unique biomarkers that can differentiate HIV-1 and HIV-2 infection.

RASSF1A Suppresses Estrogen-Dependent Breast Cancer Cell Growth through Inhibition of the Yes-Associated Protein 1 (YAP1), Inhibition of the Forkhead Box Protein M1 (FOXM1), and Activation of Forkhead Box Transcription Factor 3A (FOXO3A)

The estrogen receptor alpha (ERα) is expressed by the majority of breast cancers and plays an important role in breast cancer development and tumor outgrowth. Although ERα is well known to be a specific and efficient therapeutic target, the molecular mechanisms that are responsible for the control of ERα expression and function in the context of breast cancer initiation and progression are complex and not completely elucidated. In previous work, we have demonstrated that the tumor suppressor RASSF1A inhibits ERα expression and function in ERα-positive breast cancer cells through an AKT-dependent mechanism. Transcriptional activators such as forkhead box protein M1 (FOXM1) and forkhead transcription factor 3A (FOXO3A) and signaling pathways such as the Hippo pathway are also known to modulate ERα expression and activity. Here we report that RASSF1A acts as an inhibitor of ERα-driven breast cancer cell growth through a complex, hierarchically organized network that initially involves suppression of the Hippo effector Yes-associated protein 1 (YAP1), which is followed by inhibition of AKT1 activity, increased FOXO3A activity as well as a blockade of FOXM1 and ERα expression. Together our findings provide important new mechanistic insights into how the loss of RASSF1A contributes to ERα+ breast cancer initiation and progression.

Is REDD1 a metabolic double agent? Lessons from physiology and pathology

The Akt/mechanistic target of rapamycin (mTOR) signaling pathway governs macromolecule synthesis, cell growth, and metabolism in response to nutrients and growth factors. Regulated in development and DNA damage response (REDD)1 is a conserved and ubiquitous protein, which is transiently induced in response to multiple stimuli. Acting like an endogenous inhibitor of the Akt/mTOR signaling pathway, REDD1 protein has been shown to regulate cell growth, mitochondrial function, oxidative stress, and apoptosis. Recent studies also indicate that timely REDD1 expression limits Akt/mTOR-dependent synthesis processes to spare energy during metabolic stresses, avoiding energy collapse and detrimental consequences. In contrast to this beneficial role for metabolic adaptation, REDD1 chronic expression appears involved in the pathogenesis of several diseases. Indeed, REDD1 expression is found as an early biomarker in many pathologies including inflammatory diseases, cancer, neurodegenerative disorders, depression, diabetes, and obesity. Moreover, prolonged REDD1 expression is associated with cell apoptosis, excessive reactive oxygen species (ROS) production, and inflammation activation leading to tissue damage. In this review, we decipher several mechanisms that make REDD1 a likely metabolic double agent depending on its duration of expression in different physiological and pathological contexts. We also discuss the role played by REDD1 in the cross talk between the Akt/mTOR signaling pathway and the energetic metabolism.

Molecular characterization and expression analysis of foxo3l in response to exogenous hormones in black rockfish (Sebastes schlegelii)

As a crucial member of the Forkhead Box family, class O (FoxO) plays an essential role in growth, cell differentiation, metabolism, immunization, and apoptosis. Meanwhile, FoxO3 is the primary regulator and effective inhibitor of primordial follicle activation. In this study, seven foxo genes were identified in black rockfish (Sebastes schlegelii), including two foxo1 genes (foxo1a, foxo1b), two foxo3 genes (foxo3, foxo3l), one foxo4 gene, and two foxo6 genes (foxo6a, foxo6b). foxo3l was derived from teleost-specific whole-genome duplication events. Evaluation of tissue expression pattern revealed that foxo3l displayed sexually dimorphic expression with a high level in the ovary and spatial expression only in the cytoplasm of follicle cells and oocytes. When the ovaries were stimulated by estrogen and gonadotropin, foxo3l expression was remarkably reduced, and the effect of androgen was completely different. We considered that foxo3l lost its ability to inhibit follicular precocity because of mass ovulation by hormone stimulation, resulting in its decreased expression. Such evidence indicated that foxo3l is an important regulator of reproduction-related functions in black rockfish. This study provides new insights into foxo3l genes for further functional research in teleost.

Amino acid-dependent control of mTORC1 signaling: a variety of regulatory modes

The mechanistic target of rapamycin complex 1 (mTORC1) is an essential regulator of cell growth and metabolism through the modulation of protein and lipid synthesis, lysosome biogenesis, and autophagy. The activity of mTORC1 is dynamically regulated by several environmental cues, including amino acid availability, growth factors, energy levels, and stresses, to coordinate cellular status with environmental conditions. Dysregulation of mTORC1 activity is closely associated with various diseases, including diabetes, cancer, and neurodegenerative disorders. The discovery of Rag GTPases has greatly expanded our understanding of the regulation of mTORC1 activity by amino acids, especially leucine and arginine. In addition to Rag GTPases, other factors that also contribute to the modulation of mTORC1 activity have been identified. In this review, we discuss the mechanisms of regulation of mTORC1 activity by particular amino acids.

The ERG-Regulated LINC00920 Promotes Prostate Cancer Cell Survival via the 14-3-3ε-FOXO Pathway

Numerous noncoding transcripts have been reported to correlate with cancer development and progression. Nevertheless, there remains a paucity of long noncoding RNAs (lncRNA) with well-elucidated functional roles. Here, we leverage the International Cancer Genome Consortium-Early Onset Prostate Cancer transcriptome and identify the previously uncharacterized lncRNA LINC00920 to be upregulated in prostate tumors. Phenotypic characterization of LINC00920 revealed its positive impact on cellular proliferation, colony formation, and migration. We demonstrate that LINC00920 transcription is directly activated by ERG, an oncogenic transcription factor overexpressed in 50% of prostate cancers. Chromatin isolation by RNA purification-mass spectrometry revealed the interaction of LINC00920 with the 14-3-3ε protein, leading to enhanced sequestration of tumor suppressive FOXO1. Altogether, our results provide a rationale on how ERG overexpression, partly by driving LINC00920 transcription, could confer survival advantage to prostate cancer cells and potentially prime PTEN-intact prostate cells for cellular transformation through FOXO inactivation. IMPLICATIONS: The study describes a novel lncRNA-mediated mechanism of regulating the FOXO signaling pathway and provides additional insight into the role of ERG in prostate cancer cells.

LAMB3 promotes tumour progression through the AKT-FOXO3/4 axis and is transcriptionally regulated by the BRD2/acetylated ELK4 complex in colorectal cancer

Aberrant expression of laminin-332 promotes tumour growth and metastasis in multiple cancers. However, the dysregulated expression and mechanism of action of LAMB3, which encodes the β3 subunit of laminin-332, and the mechanism underlying dysregulated LAMB3 expression in CRC remain obscure. Here, we show that LAMB3 is overexpressed in CRC and that this overexpression is correlated with tumour metastasis and poor prognosis. Overexpression of LAMB3 promoted cell proliferation and cell migration in vitro and tumour growth and metastasis in vivo, while knockdown of LAMB3 elicited opposing effects. LAMB3 inhibited the tumour suppressive function of FOXO3/4 by activating AKT in CRC. Both the BET inhibitor JQ1 and the MEK inhibitor U0126 decreased the mRNA level of LAMB3 in multiple CRC cells. Mechanistically, ELK4 cooperated with BRD2 to regulate the transcription of LAMB3 in CRC by directly binding to the ETS binding motifs in the LAMB3 promoter. ELK4 was as acetylated at K125, which enhanced the interaction between ELK4 and BRD2. JQ1 disrupted the interaction between ELK4 and BRD2, resulting in decreased binding of BRD2 to the LAMB3 promoter and downregulation of LAMB3 transcription. Both ELK4 and BRD2 expression was associated with LAMB3 expression in CRC. LAMB3 expression was also negatively correlated with FOXO3/4 in CRC. Our study reveals the pro-tumorigenic role of LAMB3 through the AKT-FOXO3/4 axis and the transcriptional mechanism of LAMB3 in CRC, demonstrating that LAMB3 is a potential therapeutic target that can be targeted by BET inhibitors and MEK inhibitors.

The high protein expression of FOXO3, but not that of FOXO1, is associated with markers of good prognosis

To better define the role of FOXO1 and FOXO3 transcriptional factors in breast carcinogenesis, we performed a comparative study of their expression at both the RNA and protein levels in a series of human breast tumors. We used qRT-PCR assay to quantify mRNA expression and Reverse Phase Protein Arrays (RPPA) to quantify protein expression in 218 breast tumors from patients with known clinical/pathological status and outcome. Weak correlations were observed between mRNA and protein expressions for both FOXO1 and FOXO3 genes. High expression of FOXO3 protein, but not FOXO1 protein, was a good prognostic marker, negatively correlated with KI67 and markers of activity of the PI3K/AKT/mTOR oncogenic pathway, and positively correlated with p53, a marker of apoptosis. Moreover, FOXO3 protein expression, but not FOXO1 protein expression, was also negatively correlated with various proteins involved in different DNA repair mechanisms. FOXO3 protein, but not FOXO1 protein, appears to be a tumor suppressor that inhibits breast cancer by altering DNA damage response (DDR), thereby inducing p53-dependent apoptosis. This antitumor effect appears to be suppressed by excessive activity of the PI3K/AKT/mTOR pathway. High FOXO3 protein expression could be a biomarker of deficient DDR in breast tumors.

Role of FoxO3a as a negative regulator of the cardiac myofibroblast conversion induced by TGF-β1

Cardiac fibroblasts (CFs) are necessary to maintain extracellular matrix (ECM) homeostasis in the heart. Normally, CFs are quiescent and secrete small amounts of ECM components, whereas, in pathological conditions, they differentiate into more active cells called cardiac myofibroblasts (CMF). CMF conversion is characteristic of cardiac fibrotic diseases, such as heart failure and diabetic cardiomyopathy. TGF-β1 is a key protein involved in CMF conversion. SMADs are nuclear factor proteins activated by TGF-β1 that need other proteins, such as forkhead box type O (FoxO) family members, to promote CMF conversion. FoxO1, a member of this family protein, is necessary for TGF-β1-induced CMF conversion, whereas the role of FoxO3a, another FoxO family member, is unknown. FoxO3a plays an important role in many fibrotic processes in the kidney and lung. However, the participation of FoxO3a in the conversion of CFs into CMF is not clear. In this paper, we demonstrate that TGF-β1 decreases the activation and expression of FoxO3a in CFs. FoxO3a regulation by TGF-β1 requires activated SMAD3, ERK1/2 and Akt. Furthermore, we show that FoxO1 is crucial in the FoxO3a regulation induced by TGF-β1, as shown by overexpressed FoxO1 enhancing and silenced FoxO1 suppressing the effects of TGF-β1 on FoxO3a. Finally, the regulation of TGF-β1-induced CMF conversion was enhanced by FoxO3a silencing and suppressed by inhibited FoxO3a degradation. Considering these collective findings, we suggest that FoxO3a acts as a negative regulator of the CMF conversion that is induced by TGF-β1.

A key control point in the T cell response to chronic infection and neoplasia: FOXO1

T cells able to control neoplasia or chronic infections display a signature gene expression profile similar or identical to that of central memory T cells. These cells have qualities of self-renewal and a plasticity that allow them to repeatedly undergo activation (growth, proliferation, and differentiation), followed by quiescence. It is these qualities that define the ability of T cells to establish an equilibrium with chronic infectious agents, and also preserve the ability of T cells to be re-activated (by checkpoint therapy) in response to malignant cancers. Here we describe distinctions between the forms of inhibition mediated by tumors and persistent viruses, we review the properties of T cells associated with long-term immunity, and we identify the transcription factor, FOXO1, as the control point for a program of gene expression that allows CD8⁺ T cells to undergo serial reactivation and self-renewal.

17β-Estradiol Prevents Extracellular Matrix Degradation by Downregulating MMP3 Expression via PI3K/Akt/FOXO3 Pathway

STUDY DESIGN

In vitro studies of the role of 17β-estradiol (E2) and its possible targets in intervertebral disc degeneration (IDD).

OBJECTIVE

To define the regulatory role of E2 in IDD and the potential mechanisms.

SUMMARY OF BACKGROUND DATA

IDD has intricate etiology that is influenced by multiple risk factors. However, the underlying molecular mechanisms of occurrence and progression of IDD are not well elucidated. The degradation of extracellular matrix (ECM) has been extensively observed in IDD. E2 was found to inhibit ECM degradation in human nuleus pulposus cells (HNPCs), but the molecular mechanism remained to be determined.

METHODS

Western blot and qPCR was performed to quantify the expression of target proteins in HNPCs. Luciferase reporter gene assay was applied to detect the effects of E2 and forkhead box O-3 (FOXO3) on matrix metalloproteinases (MMP)-3 promoter activity. Chromatin immunoprecipitation assay analyzed the binding of FOXO3 to MMP-3 and the effect of E2 on this process.

RESULTS

We identified the upregulation of collagen II and aggrecan by E2 independent of time and concentration. And E2 downregulated MMP-3 expression in human nucleus pulposus cells. The phosphorylation of FOXO3 led to the reduction of MMP-3 promoter activity. Furthermore, 17β-estradiol-induced the activation of PI3K/Akt pathway is required for FOXO3 phosphorylated.

CONCLUSION

E2 prevents the degradation of ECM by upregulating collagen II and aggrecan expression via reducing MMP-3 expression in HNPCs, and PI3K/Akt/FOXO3 pathway is dispensable for MMP-3 downregulated. Therefore, E2 protects against IDD by preventing ECM degradation.

LEVEL OF EVIDENCE

3.

A small-molecule inhibitor of PCSK9 transcription ameliorates atherosclerosis through the modulation of FoxO1/3 and HNF1α

Background

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a secreted protein that down-regulates hepatic low-density lipoprotein receptor (LDLR) by binding and shuttling LDLR to lysosomes for degradation. The development of therapy that inhibits PCSK9 has attracted considerable attention for the management of cardiovascular disease risk. However, only monoclonal antibodies of PCSK9 have reached the clinic use. Oral administration of small-molecule transcriptional inhibitors has the potential to become a therapeutic option.

Methods

Here, we developed a cell-based small molecule screening platform to identify transcriptional inhibitors of PCSK9. Through high-throughput screening and a series of evaluation, we found several active compounds. After detailed investigation on the pharmacological effect and molecular mechanistic characterization, 7030B-C5 was identified as a potential small-molecule PCSK9 inhibitor.

Findings

Our data showed that 7030B-C5 down-regulated PCSK9 expression and increased the total cellular LDLR protein and its mediated LDL-C uptake by HepG2 cells. In both C57BL/6 J and ApoE KO mice, oral administration of 7030B-C5 reduced hepatic and plasma PCSK9 level and increased hepatic LDLR expression. Most importantly, 7030B-C5 inhibited lesions in en face aortas and aortic root in ApoE KO mice with a slight amelioration of lipid profiles. We further provide evidences suggesting that transcriptional regulation of PCSK9 by 7030B-C5 mostly depend on the transcriptional factor HNF1α and FoxO3. Furthermore, FoxO1 was found to play an important role in 7030B-C5 mediated integration of hepatic glucose and lipid metabolism.

Interpretation

7030B-C5 with potential suppressive effect of PCSK9 expression may serve as a promising lead compound for drug development of cholesterol/glucose homeostasis and cardiovascular disease therapy.

Fund

This work was supported by grants from the National Natural Science Foundation of China (81473214, 81402929, and 81621064), the Drug Innovation Major Project of China (2018ZX09711001-003-006, 2018ZX09711001-007 and 2018ZX09735001-002), CAMS Innovation Fund for Medical Sciences (2016-I2M-2-002, 2016-I2M-1-011 and 2017-I2M-1-008), Beijing Natural Science Foundation (7162129).

Molecular regulation of autophagy machinery by mTOR-dependent and -independent pathways

Macroautophagy is a lysosomal degradative pathway or recycling process that maintains cellular homeostasis. This autophagy involves a series of sequential processing events, such as initiation; elongation and nucleation of the isolation membrane; cargo recruitment and maturation of the autophagosome (AP); transport of the AP; docking and fusion of the AP with a late endosome or lysosome; and regeneration of the lysosome by the autophagic lysosomal reformation cycle. These events are critically coordinated by the action of a set of several key components, including autophagy-related proteins (Atg), and regulated by intricate networks, such as mechanistic target of rapamycin (mTOR), a master regulator of autophagy, as well as mTOR-independent signaling pathways. Among mTOR-independent pathways, the transient receptor potential (TRP) calcium ion channel TRPML (mucolipin) subfamily is emerging as an important signaling channel to modulate lysosomal biogenesis and autophagy. This review discusses the recent advances in elucidating the molecular mechanisms and regulation of the autophagy process. Understanding these mechanisms may ultimately allow scientists and clinicians to control this process in order to improve human health.

FOXO3a as a sensor of unilateral nerve injury in sensory neurons ipsilateral, contralateral and remote to injury

Emerging evidence supports that the stress response to peripheral nerve injury extends beyond the injured neuron, with alterations in associated transcription factors detected both locally and remote to the lesion. Stress-induced nuclear translocation of the transcription factor forkhead class box O3a (FOXO3a) was initially linked to activation of apoptotic genes in many neuronal subtypes. However, a more complex role of FOXO3a has been suggested in the injury response of sensory neurons, with the injured neuron expressing less FOXO3a. To elucidate this response and test whether non-injured sensory neurons also alter FOXO3a expression, the temporal impact of chronic unilateral L4–6 spinal nerve transection on FOXO3a expression and nuclear localization in adult rat dorsal root ganglion neurons ipsilateral, contralateral or remote to injury relative to naïve controls was examined. In naïve neurons, high cytoplasmic and nuclear levels of FOXO3a colocalized with calcitonin gene related peptide, a marker of the nociceptive subpopulation. One hour post-injury, an acute increase in nuclear FOXO3a in small size injured neurons occurred followed by a significant decrease after 1, 2 and 4 days, with levels increasing toward pre-injury levels by 1 week post-injury. A more robust biphasic response to the injury was observed in uninjured neurons contralateral to and those remote to injury. Nuclear levels of FOXO3a peaked at 1 day, decreased by 4 days, then increased by 1 week post-injury, a response mirrored in C4 dorsal root ganglion neurons remote to injury. This altered expression contralateral and remote to injury supports that spinal nerve damage has broader systemic impacts, a response we recently reported for another stress transcription factor, Luman/CREB3. The early decreased expression and nuclear localization of FOXO3a in the injured neuron implicate these changes in the cell body response to injury that may be protective. Finally, the broader systemic changes support the existence of stress/injury-induced humeral factor(s) influencing transcriptional and potentially behavioral changes in uninjured dorsal root ganglion neurons. Approval to conduct this study was obtained from the University of Saskatchewan Animal Research Ethics Board (protocol #19920164).

FOXO3a is stabilized by USP18-mediated de-ISGylation and inhibits TGF-β1-induced fibronectin expression

FOXO3a belongs to a family of transcription factors characterized by a conserved forkhead box DNA-binding domain. It has been known to regulate various cellular processes including cell proliferation, apoptosis and differentiation. Post-translational modifications of FOXO3a and their roles in the regulation of FOXO3a activity have been well-documented. FOXO3a can be phosphorylated, acetylated and ubiquitinated, however, the ISGylation of FOXO3a has not been reported. Protein overexpression, ISGylation and half-life were measured to determine the post-translational modification of FOXO3a. Human fibroblast cells were treated with transforming growth factor (TGF)-β1 to determine the role of FOXO3a ISGylation in TGF-β1 signaling. FOXO3a’s half-life is around 3.7 hours. Inhibition of the proteasome, not lysosome, extends its half-life. ISGylation, but not ubiquitination of FOXO3a, is increased in the presence of the proteasome inhibitor. Overexpression of ISG15 increases FOXO3a degradation, while overexpression of USP18 stabilizes FOXO3a through de-ISGylation. These results suggest that FOXO3a is degraded in the ISGylation and proteasome system, which can be reversed by USP18, an ISG15-specific deubiquitinase. This study reveals a new molecular mechanism by which ISGylation regulates FOXO3a degradation. Furthermore, we show that the overexpression of FOXO3a attenuated TGF-β1-induced fibronectin expression in human lung fibroblast cells without altering Smad2/3 expression and activation. FOXO3a can be ISGylated, which can regulate FOXO3a stability. USP18/FOXO3a pathway is a potential target for treating TGF-β1-mediated fibrotic diseases such as idiopathic pulmonary fibrosis.

Valproic Acid Addresses Neuroendocrine Differentiation of LNCaP Cells and Maintains Cell Survival

Purpose

Neuroendocrine differentiation of prostate cancer, induced by androgen deprivation therapy, is mainly related to advanced disease and poor clinical outcome. Genetic and epigenetic alterations are the key elements of the prostate carcinogenesis. A group of compounds able to induce changes in this sense is inhibitors of histone deacetylase, to which it belongs valproic acid (VPA). In the present paper, we evaluated the role of this molecule on the neuroendocrine differentiation of LNCaP cells together with the effect on proliferation and survival signals.

Methods

Cell growth was analyzed by MTT and flow cytometry, while expression of proteins through Western blot analysis.

Results

Our results have documented that VPA in LNCaP cells reduces cell proliferation, decreases the S phase and Cyclin A, and up-regulates the cyclin-dependent kinase inhibitors p21waf and p27. The acquisition of androgen-independent condition is consistent with an induction of β-III Tubulin and gamma Enolase, both markers of neuroendocrine phenotype. However, all these features cease with the removal of valproate from the culture medium, demonstrating the transitory nature of the epigenetic event. The VPA treatment does not compromise the survival phosphorylated signals of Akt, ERK1/2 and mTOR/p70S6K that remain up-regulated. Consistently, there is an increase of phospho-FOXO3a, to which corresponds the decreased expression of the corresponding oncosuppressor protein.

Conclusion

Overall, our findings indicate that VPA in LNCaP prostate tumor cells, although it reduces cell proliferation, is able to drive neuroendocrine phenotype and to maintain the survival of these cells. Keeping in mind that neuroendocrine differentiation of prostate cancer appears to be associated with a poor prognosis, it is necessary to develop new treatments that do not induce neurodifferentiation but able to counteract cell survival.

Functional reprogramming of regulatory T cells in the absence of Foxp3

Regulatory T cells (T_reg cells) deficient in the transcription factor Foxp3 lack suppressor function and manifest an effector T (T_eff) cell-like phenotype. We demonstrate that Foxp3 deficiency dysregulates metabolic checkpoint kinase mammalian target of rapamycin (mTOR) complex 2 (mTORC2) signaling and gives rise to augmented aerobic glycolysis and oxidative phosphorylation. Specific deletion of the mTORC2 adaptor gene Rictor in Foxp3-deficient T_reg cells ameliorated disease in a Foxo1 transcription factor-dependent manner. Rictor deficiency re-established a subset of T_reg cell genetic circuits and suppressed the T_eff cell-like glycolytic and respiratory programs, which contributed to immune dysregulation. Treatment of T_reg cells from patients with FOXP3 deficiency with mTOR inhibitors similarly antagonized their T_eff cell-like program and restored suppressive function. Thus, regulatory function can be re-established in Foxp3-deficient T_reg cells by targeting their metabolic pathways, providing opportunities to restore tolerance in T_reg cell disorders.

Forkhead box transcription factors as context-dependent regulators of lymphocyte homeostasis

Lymphocytes have evolved to react rapidly and robustly to changes in their local environment by using transient adaptations and by regulating their terminal differentiation programmes. Forkhead box transcription factors (FTFs) can direct leukocyte-specific responses, and their functional diversification promotes a high degree of context-dependent specification. Many, often antagonistic, FTFs have overlapping expression patterns and can thereby compete for binding to the same chromosomal target sequences. Multiple molecular mechanisms also connect extracellular signals to the expression and functionality of specific FTFs and, in this way, fine-tune their activity. Through these diverse mechanisms, FTFs can function as context-dependent rheostats responding to diverse environmental stimuli. Focusing on the various mechanisms by which their functional activity is modulated, as well as on their mechanisms of action, we discuss how specific FTFs control lymphocyte function, allowing for the establishment and maintenance of immune homeostasis.

High-throughput Exploration of the Network Dependent on AKT1 in Mouse Ovarian Granulosa Cells

The PI3K/AKT signaling pathway is known to regulate a broad range of cellular processes, and it is often altered in several types of cancers. Recently, somatic AKT1 mutations leading to a strong activation of this kinase have been reported in juvenile granulosa cell tumors. However, the molecular role of AKT1 in the supporting cell lineage of the ovary is still poorly understood. To get insights into its function in such cells, we depleted Akt1 in murine primary granulosa cells and assessed the molecular consequences at both the transcript and protein levels. We were able to corroborate the involvement of AKT1 in the regulation of metabolism, apoptosis, cell cycle, or cytoskeleton dynamics in this ovarian cell type. Consistently, we showed in established granulosa cells that depletion of Akt1 provoked altered directional persistent migration and increased its velocity. This study also allowed us to put forward new direct and indirect targets of the kinase. Indeed, a series of proteins involved in intracellular transport and mitochondrial physiology were significantly affected by Akt1 depletion. Using in silico analyses, we also propose a set of kinases and transcription factors that can mediate the action of AKT1 on the deregulated transcripts and proteins. Taken altogether, our results provide a resource of direct and indirect AKT1 targets in granulosa cells and may help understand its roles in this ovarian cell type.

High-throughput Exploration of the Network Dependent on AKT1 in Mouse Ovarian Granulosa Cells

The PI3K/AKT signaling pathway is known to regulate a broad range of cellular processes, and it is often altered in several types of cancers. Recently, somatic AKT1 mutations leading to a strong activation of this kinase have been reported in juvenile granulosa cell tumors. However, the molecular role of AKT1 in the supporting cell lineage of the ovary is still poorly understood. To get insights into its function in such cells, we depleted Akt1 in murine primary granulosa cells and assessed the molecular consequences at both the transcript and protein levels. We were able to corroborate the involvement of AKT1 in the regulation of metabolism, apoptosis, cell cycle, or cytoskeleton dynamics in this ovarian cell type. Consistently, we showed in established granulosa cells that depletion of Akt1 provoked altered directional persistent migration and increased its velocity. This study also allowed us to put forward new direct and indirect targets of the kinase. Indeed, a series of proteins involved in intracellular transport and mitochondrial physiology were significantly affected by Akt1 depletion. Using in silico analyses, we also propose a set of kinases and transcription factors that can mediate the action of AKT1 on the deregulated transcripts and proteins. Taken altogether, our results provide a resource of direct and indirect AKT1 targets in granulosa cells and may help understand its roles in this ovarian cell type.

FoxO3 activation in hypoxic tubules prevents chronic kidney disease

Acute kidney injury (AKI) can lead to chronic kidney disease (CKD) if injury is severe and/or repair is incomplete. However, the pathogenesis of CKD following renal ischemic injury is not fully understood. Capillary rarefaction and tubular hypoxia are common findings during the AKI to CKD transition. We investigated the tubular stress response to hypoxia and demonstrated that a stress responsive transcription factor, FoxO3, was regulated by prolyl hydroxylase. Hypoxia inhibited FoxO3 prolyl hydroxylation and FoxO3 degradation, thus leading to FoxO3 accumulation and activation in tubular cells. Hypoxia-activated Hif-1α contributed to FoxO3 activation and functioned to protect kidneys, as tubular deletion of Hif-1α decreased hypoxia-induced FoxO3 activation, and resulted in more severe tubular injury and interstitial fibrosis following ischemic injury. Strikingly, tubular deletion of FoxO3 during the AKI to CKD transition aggravated renal structural and functional damage leading to a more profound CKD phenotype. We showed that tubular deletion of FoxO3 resulted in decreased autophagic response and increased oxidative injury, which may explain renal protection by FoxO3. Our study indicates that in the hypoxic kidney, stress responsive transcription factors can be activated for adaptions to counteract hypoxic insults, thus attenuating CKD development.

ING4 suppresses hepatocellular carcinoma via a NF-κB/miR-155/FOXO3a signaling axis

The tumor suppressor ING4 has been shown to be reduced in human HCC. The alteration of ING4 contributes to HCC progression. However, its effect in HCC and the potential mechanism is largely unclear. Herein, we found that downregulation of ING4 in HCC tumor tissues was closely associated with cancer staging, tumor size and vascular invasion. Lentivirus-mediated ING4 overexpression significantly inhibited proliferation, migration and invasion, and induced cell cycle G1 phase arrest and apoptosis in MHCC97H human HCC cells. Moreover, overexpression of ING4 dramatically suppressed MHCC97H tumor cell growth and metastasis to lung in vivo in athymic BALB/c nude mice. Mechanistic studies revealed that overexpression of ING4 markedly increased expression of FOXO3a both at the mRNA and protein level as well as enhanced nuclear level and transcriptional activity of FOXO3a in MHCC97H tumor cells. In addition, ING4 repressed transcriptional activity of NF-κB and expression of miR-155 targeting FOXO3a. Knockdown of ING4 exhibited opposing effects in MHCC97L human HCC cells. Interestingly, knockdown of FOXO3a attenuated not only ING4-elicited tumor suppression but also ING4-mediated regulatory effect on FOXO3a downstream targets, confirming that FOXO3a is involved in ING4-directed tumor-inhibitory effect in HCC. Overexpression of miR-155 attenuated ING4-induced upregulation of FOXO3a, whereas inhibition of miR-155 blunted ING4 knockdown-induced reduction of FOXO3a. Furthermore, inhibition of NF-κB markedly impaired ING4 knockdown-induced upregulation of miR-155 and downregulation of FOXO3a. Taken together, our study provided the first compelling evidence that ING4 can suppress human HCC growth and metastasis to a great extent via a NF-κB/miR-155/FOXO3a pathway.