Silencing of PCK1 mitigates the proliferation and migration of vascular smooth muscle cells and vascular intimal hyperplasia by suppressing STAT3/DRP1-mediated mitochondrial fission.

The pathological proliferation and migration of vascular smooth muscle cells (VSMCs) are key processes during vascular neointimal hyperplasia (NIH) and restenosis. Phosphoenolpyruvate carboxy kinase 1 (PCK1) is closely related to a variety of malignant proliferative diseases. However, the role of PCK1 in VSMCs has rarely been investigated. This study aims to examine the role of PCK1 in the proliferation and migration of VSMCs and vascular NIH after injury. In vivo, extensive NIH and increased expression of PCK1 within the neointima are observed in injured arteries. Interestingly, the administration of adeno-associated virus-9 (AAV-9) carrying Pck1 short hairpin RNA (sh Pck1) significantly attenuates NIH and stenosis of the vascular lumen. In vitro, Pck1 small interfering RNA (si Pck1)-induced PCK1 silencing inhibits VSMC proliferation and migration. Additionally, silencing of PCK1 leads to reduced expression of dynamin-related protein 1 (DRP1) and attenuated mitochondrial fission. Lentivirus-mediated DRP1 overexpression markedly reverses the inhibitory effects of PCK1 silencing on VSMC proliferation, migration, and mitochondrial fission. Finally, PCK1 inhibition attenuates the phosphorylation of signal transducer and activator of transcription 3 (STAT3). Activation of STAT3 abolishes the suppressive effects of PCK1 silencing on DRP1 expression, mitochondrial fission, proliferation, and migration in VSMCs. In conclusion, PCK1 inhibition attenuates the mitochondrial fission, proliferation, and migration of VSMCs by inhibiting the STAT3/DRP1 axis, thereby suppressing vascular NIH and restenosis.

Inhibition of CIRBP represses the proliferation and migration of vascular smooth muscle cells via inhibiting Rheb/mTORC1 axis.

The excessive migration and proliferation of vascular smooth muscle cells (VSMCs) plays a vital role in vascular intimal hyperplasia. CIRBP is involved in the proliferation of various cancer cells. This study was aimed to explore the role of CIRBP in the proliferation and migration of VSMCs. Adenovirus was used to interfere with cold-inducible RNA-binding protein (CIRBP) expression, while lentivirus was used to overexpress Ras homolog enriched in brain (Rheb). Western blotting and qRT-PCR were used to evaluate the expression of CIRBP, Rheb, and mechanistic target of rapamycin complex 1 (mTORC1) activity. The cell proliferation was determined by Ki67 immunofluorescence staining and CCK-8 assay. The wound healing assay was performed to assess cell migration. Additionally, immunohistochemistry was conducted to explore the role of CIRBP in intimal hyperplasia after vascular injury. We found that silencing CIRBP inhibited the proliferation and migration of VSMCs, decreased the expression of Rheb and mTORC1 activity. Restoration of mTORC1 activity via insulin or overexpression of Rheb via lentiviral transfection both attenuated the inhibitory effects of silencing CIRBP on the proliferation and migration of VSMCs. Moreover, Rheb overexpression abolished the inhibitory effect of silencing CIRBP on mTORC1 activity in VSMCs. CIRBP was upregulated in the injured carotid artery. Silencing CIRBP ameliorated intimal hyperplasia after vascular injury. In the summary, silencing CIRBP attenuates mTORC1 activity via reducing Rheb expression, thereby supressing the proliferation and migration of VSMCs and intimal hyperplasia after vascular injury.

Recent advances of myotubularin-related (MTMR) protein family in cardiovascular diseases.

Belonging to a lipid phosphatase family containing 16 members, myotubularin-related proteins (MTMRs) are widely expressed in a variety of tissues and organs. MTMRs preferentially hydrolyzes phosphatidylinositol 3-monophosphate and phosphatidylinositol (3,5) bis-phosphate to generate phosphatidylinositol and phosphatidylinositol 5-monophosphate, respectively. These phosphoinositides (PIPs) promote membrane degradation during autophagosome-lysosomal fusion and are also involved in various regulatory signal transduction. Based on the ability of modulating the levels of these PIPs, MTMRs exert physiological functions such as vesicle trafficking, cell proliferation, differentiation, necrosis, cytoskeleton, and cell migration. It has recently been found that MTMRs are also involved in the occurrence and development of several cardiovascular diseases, including cardiomyocyte hypertrophy, proliferation of vascular smooth muscle cell, LQT1, aortic aneurysm, etc. This review summarizes the functions of MTMRs and highlights their pathophysiological roles in cardiovascular diseases.

MTMR7 suppresses the phenotypic switching of vascular smooth muscle cell and vascular intimal hyperplasia after injury via regulating p62/mTORC1-mediated glucose metabolism.

BACKGROUND AND AIMS: Myotubularin-related protein 7 (MTMR7) suppresses proliferation in various cell types and is associated with cardiovascular and cerebrovascular diseases. However, whether MTMR7 regulates vascular smooth muscle cell (VSMC) and vascular intimal hyperplasia remains unclear. We explored the role of MTMR7 in phenotypic switching of VSMC and vascular intimal hyperplasia after injury. METHODS AND RESULTS: MTMR7 expression was significantly downregulated in injured arteries. Compared to wild type (WT) mice, Mtmr7-transgenic (Mtmr7-Tg) mice showed reduced intima/media ratio, decreased percentage of Ki-67-positive cells within neointima, and increased Calponin expression in injured artery. In vitro, upregulating MTMR7 by Len-Mtmr7 transfection inhibited platelet derived growth factor (PDGF)-BB-induced proliferation, migration of VSMC and reversed PDGF-BB-induced decrease in expression of Calponin and SM-MHC. Microarray, single cell sequence, and other bioinformatics analysis revealed that MTMR7 is highly related to glucose metabolism and mammalian target of rapamycin complex 1 (mTORC1). Further experiments confirmed that MTMR7 markedly repressed glycolysis and mTORC1 activity in PDGF-BB-challenged VSMC in vitro. Restoring mTORC1 activity abolished MTMR7-mediated suppression of glycolysis, phenotypic shift in VSMC in vitro and protection against vascular intimal hyperplasia in vivo. Furthermore, upregulating MTMR7 in vitro led to dephosphorylation and dissociation of p62 from mTORC1 in VSMC. External expression of p62 in vitro also abrogated the inhibitory effects of MTMR7 on glycolysis and phenotypic switching in PDGF-BB-stimulated VSMC. CONCLUSIONS: Our study demonstrates that MTMR7 inhibits injury-induced vascular intimal hyperplasia and phenotypic switching of VSMC. Mechanistically, the beneficial effects of MTMR7 are conducted via suppressing p62/mTORC1-mediated glycolysis.

Role of Nuclear Receptor Subfamily 1 Group D Member 1 in the Proliferation, Migration of Vascular Smooth Muscle Cell, and Vascular Intimal Hyperplasia.

ABSTRACT: Excessive proliferation and migration of vascular smooth muscle cells (VSMCs) cause neointimal hyperplasia after percutaneous vascular interventions. Nuclear receptor subfamily 1 group D member 1 (NR1D1), a crucial member of circadian clock, is involved in the regulation of atherosclerosis and cellular proliferation. However, whether NR1D1 affects vascular neointimal hyperplasia remains unclear. In this study, we found that activating NR1D1 reduced injury-induced vascular neointimal hyperplasia. Overexpression of NR1D1 reduced the number of Ki-67-positive VSMCs and migrated VSMCs after platelet-derived growth factor (PDGF)-BB treatment. Mechanistically, NR1D1 suppressed the phosphorylation of AKT and 2 main effectors of the mammalian target of rapamycin complex 1 (mTORC1), S6, and 4EBP1 in PDGF-BB-challenged VSMCs. Re-activation of mTORC1 by Tuberous sclerosis 1 siRNA (si Tsc1 ) and re-activation of AKT by SC-79 abolished NR1D1-mediated inhibitory effects on proliferation and migration of VSMCs. Moreover, decreased mTORC1 activity induced by NR1D1 was also reversed by SC-79. Simultaneously, Tsc1 knockdown abolished the vascular protective effects of NR1D1 in vivo. In conclusion, NR1D1 reduces vascular neointimal hyperplasia by suppressing proliferation and migration of VSMCs in an AKT/mTORC1-dependent manner.

Nuclear receptor subfamily 1 group D member 1 suppresses the proliferation, migration of adventitial fibroblasts, and vascular intimal hyperplasia via mammalian target of rapamycin complex 1/ß-catenin pathway.

BACKGROUND: In-stent restenosis hardly limits the therapeutic effect of the percutaneous vascular intervention. Although the restenosis is significantly ameliorated after the application of new drug-eluting stents, the incidence of restenosis remains at a high level. OBJECTIVE: Vascular adventitial fibroblasts (AFs) play an important role in intimal hyperplasia and subsequent restenosis. The current study was aimed to investigate the role of nuclear receptor subfamily 1, group D, member 1 (NR1D1) in the vascular intimal hyperplasia. METHODS AND RESULTS: We observed increased expression of NR1D1 after the transduction of adenovirus carrying Nr1d1 gene (Ad-Nr1d1) in AFs. Ad-Nr1d1 transduction significantly reduced the numbers of total AFs, Ki-67-positive AFs, and the migration rate of AFs. NR1D1 overexpression decreased the expression level of ß-catenin and attenuated the phosphorylation of the effectors of mammalian target of rapamycin complex 1 (mTORC1), including mammalian target of rapamycin (mTOR) and 4E binding protein 1 (4EBP1). Restoration of ß-catenin by SKL2001 abolished the inhibitory effects of NR1D1 overexpression on the proliferation and migration of AFs. Surprisingly, the restoration of mTORC1 activity by insulin could also reverse the decreased expression of ß-catenin, attenuated proliferation, and migration in AFs induced by NR1D1 overexpression. In vivo, we found that SR9009 (an agonist of NR1D1) ameliorated the intimal hyperplasia at days 28 after injury of carotid artery. We further observed that SR9009 attenuated the increased Ki-67-positive AFs, an essential part of vascular restenosis at days 7 after injury to the carotid artery. CONCLUSION: These data suggest that NR1D1 inhibits intimal hyperplasia by suppressing the proliferation and migration of AFs in a mTORC1/ß-catenin-dependent manner.

Plin5 inhibits proliferation and migration of vascular smooth muscle cell through interacting with PGC-1α following vascular injury.

Abnormal proliferation and migration of vascular smooth muscle cell (VSMC) is a hallmark of vascular neointima hyperplasia. Perilipin 5 (Plin5), a regulator of lipid metabolism, is also confirmed to be involved in vascular disorders, such as microvascular endothelial dysfunction and atherosclerosis. To investigate the regulation and function of plin5 in the phenotypic alteration of VSMC, -an animal model of vascular intima hyperplasia was established in C57BL/6 J and Plin5 knockdown (Plin5±) mice by wire injure. Immunohistochemical staining was used to analyze neointima hyperplasia in artery. Ki-67, dihydroethidium immunofluorescence staining and wound healing assay were used to measure proliferation, reactive oxygen species (ROS) generation and migration of VSMC, respectively. Plin5 was downregulated in artery subjected to vascular injury and in VSMC subjected to platelet-derived growth factor (PDGF)-BB. Plin5 knockdown led to accelerated neointima hyperplasia, excessive proliferation and migration of VSMC after injury. In vitro, we observed increased ROS content in VSMC isolated from Plin5± mice. Antioxidative N-acetylcysteine (NAC) inhibited VSMC proliferation and migration induced by PDGF-BB or plin5 knockdown. More importantly, plin5-peroxlsome proliferator-activated receptor-γ coactivator (PGC)-1α interaction was also attenuated in VSMC after knockdown of plin5. Overexpression of PGC-1α suppressed PDGF-BB-induced ROS generation, proliferation, and migration in VSMC isolated from Plin5± mice. These data suggest that plin5 serves as a potent regulator of VSMC proliferation, migration, and neointima hyperplasia by interacting with PGC-1α and affecting ROS generation.

Inhibition of VRK1 suppresses proliferation and migration of vascular smooth muscle cells and intima hyperplasia after injury via mTORC1/ß-catenin axis.

Characterized by abnormal proliferation and migration of vascular smooth muscle cells (VSMCs), neointima hyperplasia is a hallmark of vascular restenosis after percutaneous vascular interventions. Vaccinia-related kinase 1 (VRK1) is a stress adaptionassociated ser/thr protein kinase that can induce the proliferation of various types of cells. However, the role of VRK1 in the proliferation and migration of VSMCs and neointima hyperplasia after vascular injury remains unknown. We observed increased expression of VRK1 in VSMCs subjected to platelet-derived growth factor (PDGF)-BB by western blotting. Silencing VRK1 by shVrk1 reduced the number of Ki-67-positive VSMCs and attenuated the migration of VSMCs. Mechanistically, we found that relative expression levels of ß-catenin and effectors of mTOR complex 1 (mTORC1) such as phospho (p)-mammalian target of rapamycin (mTOR), p-S6, and p-4EBP1 were decreased after silencing VRK1. Restoration of ß-catenin expression by SKL2001 and re-activation of mTORC1 by Tuberous sclerosis 1 siRNA (siTsc1) both abolished shVrk1-mediated inhibitory effect on VSMC proliferation and migration. siTsc1 also rescued the reduced expression of ß-catenin caused by VRK1 inhibition. Furthermore, mTORC1 re-activation failed to recover the attenuated proliferation and migration of VSMC resulting from shVrk1 after silencing ß-catenin. We also found that the vascular expression of VRK1 was increased after injury. VRK1 inactivation in vivo inhibited vascular injury-induced neointima hyperplasia in a ß-catenin-dependent manner. These results demonstrate that inhibition of VRK1 can suppress the proliferation and migration of VSMC and neointima hyperplasia after vascular injury via mTORC1/ß-catenin pathway. [BMB Reports 2022; 55(5): 244-249].

Inhibition of PIKfyve Ameliorates the Proliferation and Migration of Vascular Smooth Muscle Cells and Vascular Intima Hyperplasia By Reducing mTORC1 Activity.

ABSTRACT: This study was designed to investigate the role and mechanism of PIKfyve in the proliferation and migration of vascular smooth muscle cells (VSMCs) and vascular intima hyperplasia. We first observed increased protein levels of PIKfyve, phospho (p)-S6 Ribosomal Protein (S6)Ser235/236, p-4EBP1Thr37/46 in VSMCs after 24 hours of platelet-derived growth factor (PDGF)-BB treatment. By using cell counting kit-8 assay, Ki-67 immunofluorescence staining and wound healing assay, we found that PIKfyve inhibition ameliorated the enhanced activity of VSMC proliferation and migration induced by PDGF-BB. Silencing PIKfyve also suppressed the phosphorylation of S6 and 4EBP1 (2 major effectors of mammalian target of rapamycin complex 1), glucose consumption, activity of hexokinase, and LDH in PDGF-BB-challenged VSMCs. After rescuing the phosphorylation of S6 and 4EBP1 by silencing Tsc1, the suppressive effects of PIKfyve inhibition on glucose utilization, proliferation, and migration in VSMCs were abolished. The animal model of vascular restenosis was established in C57BL/6J mice by wire injury. We found the expression of PIKfyve was increased in carotid artery at day 28 after injury. Reducing the activity of PIKfyve alleviated vascular neointima hyperplasia after injury. In conclusion, targeting PIKfyve might be a novel effective method to reduce the proliferation and migration of VSMCs and vascular restenosis by affecting mammalian target of rapamycin complex 1-mediated glucose utilization.

Postnatal renin-angiotensin system inhibition prevents renal damage from prenatal inflammation in rats.

OBJECTIVE: To assess the protective role of benazepril, an angiotensin-converting enzyme inhibitor, in renal damage caused by prenatal inflammation. METHODS: Saline or lipopolysaccharide were administered intraperitoneally to pregnant Sprague- Dawley rats on gestation days 8, 10, and 12. After birth, offspring received either tap water or benazepril in water between 7 and 68 weeks. Blood pressure, blood urea nitrogen, creatinine, and 24-h urine volume were measured as indices of renal function. Hematoxylin, eosin, periodic acid-Schiff, and Sirius Red staining were used to evaluate renal damage. RESULTS: Postnatal benazepril treatment ameliorated hypertension and restored normal 24-h urine volume and blood urea nitrogen and serum creatinine levels. Benazepril treatment also reduced glycoprotein accumulation and fibrosis in the glomerulus and in tubular epithelial cells and inhibited nuclear factor-kappa B activation. CONCLUSION: Together with our previous findings that postnatal inhibition of nuclear factor-kappa B activation blocks intra-renal renin-angiotensin system activation, our current data demonstrate that intra-renal activation of the renin-angiotensin system interacts with nuclear factor-kappa B activation to cause renal damage in adulthood following prenatal inflammation.

NF2 deficiency accelerates neointima hyperplasia following vascular injury via promoting YAP-TEAD1 interaction in vascular smooth muscle cells.

Neurofibromin 2 (NF2), a potent tumor suppressor, is reported to inhibit proliferation in several cell types. The role of NF2 in neointima hyperplasia after vascular injury is unknown. We explored the role of NF2 in proliferation, migration of vascular smooth muscle cell (VSMC) and neointima hyperplasia after vascular injury. NF2 phosphorylation was elevated in VSMC subjected to platelet-derived growth factor (PDGF)-BB and in artery subjected to vascular injury. Mice deficient for Nf2 in VSMC showed enhanced neointima hyperplasia after injury, increased proliferation and migration of VSMC after PDGF-BB treatment. Mechanistically, we observed increased nuclear p-NF2, declined p-Yes-Associated Protein (YAP), nuclear translocation of YAP after PDGF-BB treatment or injury. NF2 knockdown or YAP overexpression showed similar phenotype in VSMC proliferation, migration and neointima hyperplasia. YAP inhibition abolished the above effects mediated by NF2 knockdown. Finally, NF2 knockdown further promoted YAP-TEA Domain Transcription Factor 1 (TEAD1) interaction after PDGF-BB treatment. Inhibition of TEAD1 blocked PDGF-BB-induced VSMC proliferation and migration, which were not reversed by either NF2 knockdown or YAP overexpression. In conclusion, NF2 knockdown promotes VSMC proliferation, migration and neointima hyperplasia after vascular injury via inducing YAP-TEAD1 interaction.

Role of polypyrimidine tract-binding protein 1/yin yang 2 signaling in regulating vascular smooth muscle cell proliferation and neointima hyperplasia.

Abnormal proliferation of vascular smooth muscle cells (VSMCs) is a hallmark of vascular restenosis. We investigated whether polypyrimidine tract-binding protein 1 (PTBP1), a novel regulator of cell proliferation and differentiation, is implicated in VSMC proliferation and neointima hyperplasia responding to injury. C57BL/6 J mice of 10-12 weeks old were randomly divided into sham and carotid artery injury group. Primary VSMCs obtained from thoracic aortas of 10- to 12-week-old mice were treated with physiological saline and platelet derived growth factor-BB (PDGF-BB). Adenovirus expressing shCon, shPTBP1 or shYY2 were transfected into the injured common carotid artery or VSMCs. qRT-PCR and immunoblotting were used to determine the mRNA and protein expression levels, respectively. Immunohistochemical staining of H&E and Ki-67 were used to evaluate restenosis of vessels. Cell counting kit-8 assay and Ki-67 immunofluorescent staining were utilized to evaluate the rate of VSMC proliferation. The expression of PTBP1 were upregulated both in injured arteries and in PDGF-BB-treated VSMCs. PTBP1 inhibition significantly attenuated neointima hyperplasia and Ki-67 positive area induced by injury. Knockdown of PTBP1 in vitro also suppressed VSMC proliferation after PDGF-BB treatment. The effects of PTBP1 inhibition mentioned above were all abolished by knockdown of YY2. Finally, we identified four cell cycle regulators (p53, p21, Cdkn1c, Cdkn2b) that were regulated by PTBP1/YY2 axis both in vitro and in vivo. These findings demonstrated that PTBP1 is a critical regulator of VSMC proliferation and neointima hyperplasia via modulating the expression of YY2.

TRPA1 Promotes Cardiac Myofibroblast Transdifferentiation after Myocardial Infarction Injury via the Calcineurin-NFAT-DYRK1A Signaling Pathway.

Cardiac fibroblasts (CFs) are a critical cell population responsible for myocardial extracellular matrix homeostasis. After stimulation by myocardial infarction (MI), CFs transdifferentiate into cardiac myofibroblasts (CMFs) and play a fundamental role in the fibrotic healing response. Transient receptor potential ankyrin 1 (TRPA1) channels are cationic ion channels with a high fractional Ca2+ current, and they are known to influence cardiac function after MI injury; however, the molecular mechanisms regulating CMF transdifferentiation remain poorly understood. TRPA1 knockout mice, their wild-type littermates, and mice pretreated with the TRPA1 agonist cinnamaldehyde (CA) were subjected to MI injury and monitored for survival, cardiac function, and fibrotic remodeling. TRPA1 can drive myofibroblast transdifferentiation initiated 1 week after MI injury. In addition, we explored the underlying mechanisms via in vitro experiments through gene transfection alone or in combination with inhibitor treatment. TRPA1 overexpression fully activated CMF transformation, while CFs lacking TRPA1 were refractory to transforming growth factor ß- (TGF-ß-) induced transdifferentiation. TGF-ß enhanced TRPA1 expression, which promoted the Ca2+-responsive activation of calcineurin (CaN). Moreover, dual-specificity tyrosine-regulated kinase-1a (DYRK1A) regulated CaN-mediated NFAT nuclear translocation and TRPA1-dependent transdifferentiation. These findings suggest a potential therapeutic role for TRPA1 in the regulation of CMF transdifferentiation in response to MI injury and indicate a comprehensive pathway driving CMF formation in conjunction with TGF-ß, Ca2+ influx, CaN, NFATc3, and DYRK1A.

Wild-type p53-induced phosphatase 1 promotes vascular smooth muscle cell proliferation and neointima hyperplasia after vascular injury via p-adenosine 5'-monophosphate-activated protein kinase/mammalian target of rapamycin complex 1 pathway.

OBJECTIVES: Vascular smooth muscle cell (VSMC) proliferation is a crucial cause of vascular neointima hyperplasia and restenosis, thus limiting the long-term efficacy of percutaneous vascular intervention. We explored the role of wild-type p53-induced phosphatase 1 (Wip1), a potent regulator of tumorigenesis and atherosclerosis, in VSMC proliferation and neointima hyperplasia. METHODS AND RESULTS: Animal model of vascular restenosis was established in wild type C57BL/6J and VSMC-specific Tuberous Sclerosis 1 (TSC1)-knockdown mice by wire injury. We observed increased protein levels of Wip1, phospho (p)-S6 Ribosomal Protein (S6), p-4EBP1 but decreased p-adenosine 5'-monophosphate-activated protein kinase (AMPK)α both in carotid artery at day 28 after injury and in VSMCs after 48 h of platelet derived growth factor-BB (PDGF-BB) treatment. By using hematoxylin-eosin staining, Ki-67 immunohistochemical staining, cell counting kit-8 assay and Ki-67 immunofluorescence staining, we found Wip1 antagonist GSK2830371 (GSK) or mammalian target of rapamycin complex 1 (mTORC1) inhibitor rapamycin both obviously reversed the neointima formation and VSMC proliferation induced by wire injury and PDGF-BB, respectively. GSK also reversed the increase in mRNA level of Collagen I after wire injury. However, GSK had no obvious effects on VSMC migration induced by PDGF-BB. Simultaneously, TSC1 knockdown as well as AMPK inhibition by Compound C abolished the vascular protective and anti-proliferative effects of Wip1 inhibition. Additionally, suppression of AMPK also reversed the declined mTORC1 activity by GSK. CONCLUSION: Wip1 promotes VSMC proliferation and neointima hyperplasia after wire injury via affecting AMPK/mTORC1 pathway.

Pre-exposure to 50 Hz-electromagnetic fields enhanced the antiproliferative efficacy of 5-fluorouracil in breast cancer MCF-7 cells.

Resistance to 5-fluorouracil (5-FU) and its induced immune suppression have prevented its extensive application in the clinical treatment of breast cancer. In this study, the combined effect of 50 Hz-EMFs and 5-FU in the treatment of breast cancer was explored. MCF-7 and MCF10A cells were pre-exposed to 50 Hz-EMFs for 0, 2, 4, 8 and 12 h and then treated with different concentrations of 5-FU for 24 h; cell viability was analyzed by MTT assay and flow cytometry. After pre-exposure to 50 Hz-EMFs for 12 h, apoptosis and cell cycle distribution in MCF-7 and MCF10A cells were detected via flow cytometry and DNA synthesis was measured by EdU incorporation assay. Apoptosis-related and cell cycle-related gene and protein expression levels were monitored by qPCR and western blotting. Pre-exposure to 50 Hz-EMFs for 12 h enhanced the antiproliferative effect of 5-FU in breast cancer cell line MCF-7 in a dose-dependent manner but not in normal human breast epithelial cell line MCF10A. Exposure to 50 Hz-EMFs had no effect on apoptosis and P53 expression of MCF-7 and MCF10A cells, whereas it promoted DNA synthesis, induced entry of MCF-7 cells into the S phase of cell cycle, and upregulated the expression levels of cell cycle-related proteins Cyclin D1 and Cyclin E. Considering the pharmacological mechanisms of 5-FU in specifically disrupting DNA synthesis, this enhanced inhibitory effect might have resulted from the specific sensitivity of MCF7 cells in active S phase to 5-FU. Our findings demonstrate the enhanced cytotoxic activity of 5-FU on MCF7 cells through promoting entry into the S phase of the cell cycle via exposure to 50 Hz-EMFs, which provides a novel method of cancer treatment based on the combinatorial use of 50 Hz-EMFs and chemotherapy.

Downregulation of ATG5-dependent macroautophagy by chaperone-mediated autophagy promotes breast cancer cell metastasis.

Recent data have shown that the expression of lysosome-associated membrane protein type 2 A (LAMP2A), the key protein in the chaperone-mediated autophagy (CMA) pathway, is elevated in breast tumor tissues. However, the exact effects and mechanisms of CMA during breast cancer metastasis remain largely unknown. In this study, we found that the LAMP2A protein level was significantly elevated in human breast cancer tissues, particularly in metastatic carcinoma. The increased LAMP2A level was also positively correlated with the histologic grade of ductal breast cancer. High LAMP2A levels also predicted shorter overall survival of breast cancer patients. Downregulation of CMA activity by LAMP2A knockdown significantly inhibited the growth and metastasis of both MDA-MB-231 and MDA-MB-468 breast cancer cells in vivo and in vitro, while upregulation of CMA activity by LAMP2A overexpression had the opposite effect. Mechanistically, we found that elevated CMA activity mediated increased growth and metastasis of human breast cancer cells by downregulating the activity of autophagy-related gene 5 (ATG5)-dependent macroautophagy. Collectively, these results indicate that the anti-macroautophagic property is a key feature of CMA-mediated tumorigenesis and metastasis and may, in some contexts, serve as an attractive target for breast cancer therapies.

Profiling analysis of long non-coding RNAs in early postnatal mouse hearts.

Mammalian cardiomyocytes undergo a critical hyperplastic-to-hypertrophic growth transition at early postnatal age, which is important in establishing normal physiological function of postnatal hearts. In the current study, we intended to explore the role of long non-coding (lnc) RNAs in this transitional stage. We analyzed lncRNA expression profiles in mouse hearts at postnatal day (P) 1, P7 and P28 via microarray. We identified 1,146 differentially expressed lncRNAs with more than 2.0-fold change when compared the expression profiles of P1 to P7, P1 to P28, and P7 to P28. The neighboring genes of these differentially expressed lncRNAs were mainly involved in DNA replication-associated biological processes. We were particularly interested in one novel cardiac-enriched lncRNA, ENSMUST00000117266, whose expression was dramatically down-regulated from P1 to P28 and was also sensitive to hypoxia, paraquat, and myocardial infarction. Knockdown ENSMUST00000117266 led to a significant increase of neonatal mouse cardiomyocytes in G0/G1 phase and reduction in G2/M phase, suggesting that ENSMUST00000117266 is involved in regulating cardiomyocyte proliferative activity and is likely associated with hyperplastic-to-hypertrophic growth transition. In conclusion, our data have identified a large group of lncRNAs presented in the early postnatal mouse heart. Some of these lncRNAs may have important functions in cardiac hyperplastic-to-hypertrophic growth transition.

Maternal inflammation activated ROS-p38 MAPK predisposes offspring to heart damages caused by isoproterenol via augmenting ROS generation.

Maternal inflammation contributes to the increased incidence of adult cardiovascular disease. The current study investigated the susceptibility of cardiac damage responding to isoproterenol (ISO) in adult offspring that underwent maternal inflammation (modeled by pregnant Sprague-Dawley rats with lipopolysaccharides (LPS) challenge). We found that 2 weeks of ISO treatment in adult offspring of LPS-treated mothers led to augmented heart damage, characterized by left-ventricular systolic dysfunction, cardiac hypertrophy and myocardial fibrosis. Mechanistically, prenatal exposure to LPS led to up-regulated expression of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, antioxidant enzymes, and p38 MAPK activity in left ventricular of adult offspring at resting state. ISO treatment exaggerated ROS generation, p38 MAPK activation but down-regulated reactive oxygen species (ROS) elimination capacity in the left ventricular of offspring from LPS-treated mothers, while antioxidant N-acetyl-L-cysteine (NAC) reversed these changes together with improved cardiac functions. The p38 inhibitor SB202190 alleviated the heart damage only via inhibiting the expression of NADPH oxidases. Collectively, our data demonstrated that prenatal inflammation programs pre-existed ROS activation in the heart tissue, which switches on the early process of oxidative damages on heart rapidly through a ROS-p38 MAPK-NADPH oxidase-ROS positive feedback loop in response to a myocardial hypertrophic challenge in adulthood.

Post-Natal Inhibition of NF-κB Activation Prevents Renal Damage Caused by Prenatal LPS Exposure.

Prenatal exposure to an inflammatory stimulus has been shown to cause renal damage in offspring. Our present study explored the role of intra-renal NF-κB activation in the development of progressive renal fibrosis in offspring that underwent prenatal exposure to an inflammatory stimulus. Time-dated pregnant rats were treated with saline (control group) or 0.79 mg/kg lipopolysaccharide (LPS) through intra-peritoneal injection on gestational day 8, 10 and 12. At the age of 7 weeks, offspring from control or LPS group were treated with either tap water (Con+Ve or LPS+Ve group) or pyrollidine dithiocarbamate (PDTC, 120 mg/L), a NF-κB inhibitor, via drinking water starting (Con+PDTC or LPS+PDTC group), respectively, till the age of 20 or 68 weeks. The gross structure of kidney was assessed by hematoxylin-eosin, periodic acid-Schiff staining and Sirius red staining. The expression levels of TNF-α, IL-6, α-smooth muscle actin (α-SMA) and renin-angiotensin system (RAS) genes were determined by real time polymerase chain reaction and/or immunohistochemical staining. Our data showed that post-natal persistent PDTC administration efficiently repressed intra-renal NF-κB activation, TNF-α and IL-6 expression. Post-natal PDTC also prevented intra-renal glycogen deposition and collagenous fiber generation as evident by the reduced expression of collagen III and interstitial α-SMA in offspring of prenatal LPS exposure. Furthermore, post-natal PDTC administration reversed the intra-renal renin-angiotensin system (RAS) over-activity in offspring of prenatal LPS exposure. In conclusion, prenatal inflammatory exposure results in offspring's intra-renal NF-κB activation along with inflammation which cross-talked with excessive RAS activation that caused exacerbation of renal fibrosis and dysfunction in the offspring. Thus, early life prevention of NF-κB activation may be a potential preventive strategy for chronic renal inflammation and progressive renal damage.