HIF-1α knockdown by miRNA decreases survivin expression and inhibits A549 cell growth in vitro and in vivo

FSTL3 promotes colorectal cancer by activating the HIF1 pathway

Follistatin-like 3 (FSTL3) is a glycoprotein known to promote tumor growth, invasion, and angiogenesis in various cancers. However, its role in Colorectal Cancer (CRC), particularly concerning the hypoxia-inducible factor 1α (HIF1α) signaling pathway, remains unclear. The HIF1α pathway is critical in CRC progression, enabling tumor cells to adapt to hypoxia through angiogenesis, Epithelial-Mesenchymal Transition (EMT), and metabolic reprogramming. Analysis of The Cancer Genome Atlas (TCGA) and GSE39582 datasets revealed that FSTL3 is significantly upregulated in CRC tissues and correlates with poor Overall Survival (OS), Progression-Free Survival (PFS), and aggressive features such as venous, lymphatic, and perineural invasion. In vitro experiments demonstrated that FSTL3 overexpression in HCT15 and HCT116 cells promoted proliferation, migration, and cell cycle progression, whereas knockdown in LOVO and Caco2 cells suppressed these processes and induced apoptosis. Transcriptome sequencing and western blot analysis indicated that FSTL3 activated the HIF1α pathway by upregulating HIF1α, ANGPT2, and HK3, which are key regulators of angiogenesis and glycolysis. Importantly, treatment with the HIF1α inhibitor KC7F2 reversed the oncogenic effects of FSTL3 overexpression both in vitro and in vivo. In xenograft and tail vein metastasis models, KC7F2 suppressed tumor growth, reduced pulmonary metastasis, and restored lung tissue integrity, further downregulating FSTL3 and HIF1α expression. These findings suggest that FSTL3 promotes CRC progression via the HIF1α pathway and highlight its potential as a prognostic biomarker and therapeutic target for CRC treatment.

C/EBPβ Regulates HIF-1α-Driven Invasion of Non-Small-Cell Lung Cancer Cells

Metastatic cancer accounts for most cancer-related deaths, and identifying specific molecular targets that contribute to metastatic progression is crucial for the development of effective treatments. Hypoxia, a feature of solid tumors, plays a role in cancer progression by inducing resistance to therapy and accelerating metastasis. Here, we report that CCAAT/enhancer-binding protein beta (C/EBPβ) transcriptionally regulates hypoxia-inducible factor 1 subunit alpha (HIF1A) and thus promotes migration and invasion of non-small-cell lung cancer (NSCLC) cells under hypoxic conditions. Our results show that knockdown or forced expression of C/EBPβ was correlated with HIF-1α expression and that C/EBPβ directly bound to the promoter region of HIF1A. Silencing HIF1A inhibited the enhanced migration and invasion induced by C/EBPβ overexpression in NSCLC cells under hypoxia. Expression of the HIF-1α target gene, SLC2A1, was also altered in a C/EBPβ-dependent manner, and knockdown of SLC2A1 reduced migration and invasion enhanced by C/EBPβ overexpression. These results indicate that C/EBPβ is a critical regulator for the invasion of NSCLC cells in the hypoxic tumor microenvironment. Collectively, the C/EBPβ-HIF-1α-GLUT1 axis represents a potential therapeutic target for preventing metastatic progression of NSCLC and improving patient outcomes.

A reductionist perspective on HIF-1α's role in cell proliferation under non-hypoxic conditions

The role of hypoxia-inducible factor (HIF)-1α in the control of proliferation under non-hypoxic conditions has been investigated in numerous studies, but does not yield a coherent picture. Therefore, we conducted this meta-analysis of existing literature to systematically evaluate the role of HIF-1α, based on a number of inclusion and exclusion criteria. Studies analyzing non-transformed, primary cells showed a largely heterogeneous distribution of pro-proliferative, anti-proliferative or absent functions for HIF-1α, which are co-determined by several parameters, including the type and age of the cell and its localization in tissues and organs. In contrast, the analyses of tumor cells showed a predominantly pro-proliferative role of HIF-1α by cell-intrinsic and cell-extrinsic molecular mechanism not yet understood.

Benzo[a]pyrene at human blood equivalent level induces human lung epithelial cell invasion and migration via aryl hydrocarbon receptor signaling

Benzo[a]pyrene (B[a]P), a typical carcinogenic polycyclic aromatic hydrocarbon, exists worldwide in vehicle exhaust, cigarette smoke and other polluted environments. Recent studies have demonstrated a strong association between B[a]P and lung cancer. However, whether B[a]P at human blood equivalent level can promote epithelial-mesenchymal transition (EMT), a crucial molecular event during cell malignant transformation, remains unclear. Besides, whether B[a]P facilitates this progress via aryl hydrocarbon receptor (AhR) signaling pathway also lacks scientific evidence. In our study, the transwell assay showed that 5 μg/L of B[a]P promoted BEAS-2B cell invasion and migration. In addition, the mRNA and protein expression levels of AhR and its target genes involved in B[a]P metabolism, such as AhR nuclear translocator, heat shock protein 90 and CYP1A1, were significantly increased by B[a]P exposure. Moreover, the mRNA expression levels of downstream regulatory factors related to both AhR signaling pathway and EMT, such as NRF2, K-RAS and hypoxia-inducible factor 1-alpha, were significantly increased. Furthermore, the expression level of the epithelial marker E-cadherin was significantly downregulated, while the mRNA expression of mesenchymal phenotype markers, N-cadherin, fibronectin and vimentin, were significantly upregulated. Notably, the above changes induced by B[a]P were significantly attenuated or even stopped by resveratrol (RSV), a natural phenol, also an AhR inhibitor, when the AhR signaling pathway was inhibited by RSV, demonstrating the regulatory role of AhR signaling pathway in B[a]P-induced EMT. In conclusion, B[a]P at the human blood equivalent level induces BEAS-2B cell invasion and migration through the AhR signaling pathway.

How to Modulate Tumor Hypoxia for Preclinical In Vivo Imaging Research

Tumor hypoxia is related with tumor aggressiveness, chemo- and radiotherapy resistance, and thus a poor clinical outcome. Therefore, over the past decades, every effort has been made to develop strategies to battle the negative prognostic influence of tumor hypoxia. For appropriate patient selection and follow-up, noninvasive imaging biomarkers such as positron emission tomography (PET) radiolabeled ligands are unprecedentedly needed. Importantly, before being able to implement these new therapies and potential biomarkers into the clinical setting, preclinical in vivo validation in adequate animal models is indispensable. In this review, we provide an overview of the different attempts that have been made to create differential hypoxic in vivo cancer models with a particular focus on their applicability in PET imaging studies.

The Lipid Side of Bone Marrow Adipocytes: How Tumor Cells Adapt and Survive in Bone

PURPOSE OF REVIEW

Bone marrow adipocytes have emerged in recent years as key contributors to metastatic progression in bone. In this review, we focus specifically on their role as the suppliers of lipids and discuss pro-survival pathways that are closely linked to lipid metabolism, affected by the adipocyte-tumor cell interactions, and likely impacting the ability of the tumor cell to thrive in bone marrow space and evade therapy.

RECENT FINDINGS

The combined in silico, pre-clinical, and clinical evidence shows that in adipocyte-rich tissues such as bone marrow, tumor cells rely on exogenous lipids for regulation of cellular energetics and adaptation to harsh metabolic conditions of the metastatic niche. Adipocyte-supplied lipids have a potential to alter the cell's metabolic decisions by regulating glycolysis and respiration, fatty acid oxidation, lipid desaturation, and PPAR signaling. The downstream effects of lipid signaling on mitochondrial homeostasis ultimately control life vs. death decisions, providing a mechanism for gaining survival advantage and reduced sensitivity to treatment. There is a need for future research directed towards identifying the key metabolic and signaling pathways that regulate tumor dependence on exogenous lipids and consequently drive the pro-survival behavior in the bone marrow niche.

Role of Hypoxia-Inducible Factors 1α (HIF1α) in SH-SY5Y Cell Autophagy Induced by Oxygen-Glucose Deprivation

Background

HIF-1α plays an important role in hypoxia-ischemia brain damage. Accumulating evidences demonstrates that HIF-1α can contribute to cell autophagy. Oxygen-glucose deprivation (OGD) is a commonly used ischemic model in vitro. Our study was performed to investigate the influences of HIF-1α on autophagy in SH-SY5Y cells under OGD treatment.

Material/Methods

An OGD model was constructed in SH-SY5Y cells. PI method and MTT assay were used to test cell death and viability, respectively. Western blot assay was used to estimate the protein levels of HIF-1α and LC3. Quantitative GFP-LC3 light microscopy autophagy assay was performed for SH-SY5Y cells. 2ME2 and siRNA-HIF-1α were applied to investigate the effects of HIF-1α-knockdown on LC3 expression. Additionally, 3-MA (autophagy inhibitor) and autophagy inducer rapamycin (Rapa) were used to investigate the effects of autophagy on cell survival under OGD condition.

Results

Under OGD, the apoptosis of SH-SY5Ycells was increased while cell viability rate was decreased. The expression of HIF-1α was increased along with the advancement of OGD treatment and achieved the highest level at 24 h. However, inhibiting HIF-1α expression decreased the cell apoptosis and increased cell viability. LC3-II expression was gradually increased with the duration of OGD condition and knockdown of HIF-1α resulted in decreased expression of LC3. Inhibiting autophagy significantly enhanced the viability and reduced the apoptosis of SH-SY5Y cells, while enhancing autophagy showed the opposite effects.

Conclusions

Enhanced expression of HIF-1α may be related to autophagy activation in SH-SY5Y cells, thus contributing to ischemic/hypoxic brain damage.

HIF-2α dictates the susceptibility of pancreatic cancer cells to TRAIL by regulating survivin expression

Cancer cells develop resistance to therapy by adapting to hypoxic microenvironments, and hypoxia-inducible factors (HIFs) play crucial roles in this process. We investigated the roles of HIF-1α and HIF-2α in cancer cell death induced by tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) using human pancreatic cancer cell lines. siRNA-mediated knockdown of HIF-2α, but not HIF-1α, increased susceptibility of two pancreatic cancer cell lines, Panc-1 and AsPC-1, to TRAIL in vitro under normoxic and hypoxic conditions. The enhanced sensitivity to TRAIL was also observed in vivo. This in vitro increased TRAIL sensitivity was observed in other three pancreatic cancer cell lines. An array assay of apoptosis-related proteins showed that knockdown of HIF-2α decreased survivin expression. Additionally, survivin promoter activity was decreased in HIF-2α knockdown Panc-1 cells and HIF-2α bound to the hypoxia-responsive element in the survivin promoter region. Conversely, forced expression of the survivin gene in HIF-2α shRNA-expressing Panc-1 cells increased resistance to TRAIL. In a xenograft mouse model, the survivin suppressant YM155 sensitized Panc-1 cells to TRAIL. Collectively, our results indicate that HIF-2α dictates the susceptibility of human pancreatic cancer cell lines, Panc-1 and AsPC-1, to TRAIL by regulating survivin expression transcriptionally, and that survivin could be a promising target to augment the therapeutic efficacy of death receptor-targeting anti-cancer therapy.

Adipocyte-activated oxidative and ER stress pathways promote tumor survival in bone via upregulation of Heme Oxygenase 1 and Survivin

Metastatic tumor cells engage the local tumor microenvironment and activate specific pro-survival mechanisms to thrive and progress in the harsh bone marrow niche. Here we show that the major contributors to the survival of carcinoma cells that have colonized the bone marrow are the adipocyte-induced oxidative stress and ER stress pathways. We demonstrate that upon exposure to adipocyte-rich environments in vitro or in vivo, bone-trophic prostate and breast tumor cells upregulate the oxidative stress enzyme, HO-1. We also show that HO-1 levels are significantly increased in human metastatic prostate cancer tissues and that stable HO-1 overexpression in tumor cells promotes growth and invasiveness. Co-incident with the adipocyte-induced expression of HO-1, there is an upregulation of ER chaperone BIP and splicing of XBP1, indicating adipocyte-driven unfolded protein response, a process that we show to be sensitive to antioxidant treatment. Importantly, we also demonstrate that triggering of the oxidative stress and ER stress responses, or HO-1 induction by adipocyte exposure result in the activation of pro-survival pathways, involving survivin. Collectively, our findings reveal a new link between HO-1 and survivin expression in tumor cells, and provide a new insight into potentially targetable survival pathways in bone-metastatic disease.

SL4, a chalcone-based compound, induces apoptosis in human cancer cells by activation of the ROS/MAPK signalling pathway

OBJECTIVES

SL4, a chalcone-based compound, exhibits clearly inhibitory effects on HIF-1 and has been shown to effectively suppress tumour invasion and angiogenesis in vitro and in vivo. Here, studies were conducted to determine SL4's anti-apoptotic effects and its underlying mechanisms, in human cancer cells.

MATERIALS AND METHODS

Cytotoxicity, apoptotic induction and its involved mechanisms of SL4 were investigated using normal cells, cancer cells and mouse xenograft models. The role of reactive oxygen species (ROS) and mitogen-activated protein kinase (MAPK) signalling in SL4-induced apoptosis was explored by manipulating specific scavenger or signalling inhibitors, in cultured cells.

RESULTS

SL4 significantly inhibited cell population growth of human cancer cell lines but exhibited lower cytotoxicity against normal cells. In addition, SL4 effectively induced apoptosis of Hep3B and MDA-MB-435 cells by activating procaspase-8, -9 and -3, and down-regulating expression levels of XIAP, but did not affect HIF-1 apoptosis-related targets, Survivin and Bcl-XL. Further study showed that SL4 also reduced mitochondrial membrane potential and promoted generation of ROS. ROS generation and apoptotic induction by SL4 were blocked by NAC, a scavenger of ROS, suggesting SL4-induced apoptosis via ROS accumulation. We also found that MAPKs, JNK and p38, but not ERK1/2, to be critical mediators in SL4-induced apoptosis. SP600125 and SB203580, specific inhibitors of JNK kinase and p38 kinase, significantly retarded apoptosis induced by SL4. Moreover, anti-oxidant NAC blocked activation of JNK and p38 induced by SL4, indicating that ROS may act as upstream signalling of JNK and p38 activation. It is noteworthy that animal studies revealed dramatic reduction (49%) in tumour volume after 11 days SL4 treatment.

CONCLUSIONS

These data demonstrate that SL4 induced apoptosis in human cancer cells through activation of the ROS/MAPK signalling pathway, suggesting that it may be a novel lead compound, as a cancer drug candidate, with polypharmacological characteristics.

The twisted survivin connection to angiogenesis

Survivin, a member of the inhibitor of apoptosis family of proteins (IAPs) that controls cell division, apoptosis, metastasis and angiogenesis, is overexpressed in essentially all human cancers. As a consequence, the gene/protein is considered an attractive target for cancer treatment. Here, we discuss recent findings related to the regulation of survivin expression and its role in angiogenesis, particularly in the context of hypoxia. We propose a novel role for survivin in cancer, whereby expression of the protein in tumor cells promotes VEGF synthesis, secretion and angiogenesis. Mechanistically, we propose the existence of a positive feed-back loop involving PI3-kinase/Akt activation and enhanced β-Catenin-TCF/LEF-dependent VEGF expression followed by secretion. Finally, we elaborate on the possibility that this mechanism operating in cancer cells may contribute to enhanced tumor vascularization by vasculogenic mimicry together with conventional angiogenesis.

The involvement of survivin in insulin-like growth factor 1-induced epithelial-mesenchymal transition in gastric cancer

It has been identified that insulin-like growth factor 1 (IGF-1) activated various pathways of the epithelial-mesenchymal transition (EMT) in a couple of tumors. At the same time, survivin is implicated in EMT of gastric cancer (GC). To date, the impact of survivin on IGF-1-mediated EMT of GC has not been featured. In this work, we used the immunohistochemistry and molecular and cellular experiments to investigate the existence and significance of IGF-1 and survivin. Our findings revealed that survivin protein can be observed in majority of samples in all GC samples. Importantly, survivin expression has an obvious association with GC stage, and metastasis. In vitro, GC cell line BGC823 was treated with different concentrations of IGF-1, resulting in the activation of p-ERK, p-AKT, survivin, and the expression of EMT biomarkers, including N-cadherin, MMP2, and Snail. However, the silencing of survivin eradicated the expression IGF-1-induced EMT biomarkers and affected the migration and invasion of BGC823 cells. In conclusion, IGF-1 signaling activated survivin expression and controlled the expression of EMT biomarkers in the development of GC. This study lays a new stage for the molecular therapy of GC patients in the clinical treatment.

Survivin contributes to the progression of diabetic retinopathy through HIF-1α pathway

Hypoxia plays a critical role in the formation of diabetic retinopathy (DR). Hypoxia inducible factor-1α (HIF-1α) and survivin are upregulated following hypoxia, and contribute to the angiogenesis in cancer. The goal of our study was to investigate if the expression of HIF-1α and survivin is related to the retinal vascular change of rats with different stages of diabetes mellitus (DM). Wistar rats were randomly divided into DM for 1 month (DM1) group, DM3, DM6 group and normal control group. Streptozotocin (STZ) was used to induce diabetic rat models. Retinal vascular digest preparation was taken to observe the change of retinal microvessels. The expression of HIF-1α and survivin was determined by real-time PCR and Western blot. In DM3 group, capillaries became circuitous and irregular. Acellular capillary were detected in DM6 group. In the same time, the number of pericytes significantly decreased in DM3 and DM6 groups. The expressions of HIF-1α were more increased in the DM3 and DM6 groups. However, the expressions of survivin only were upregulated in DM6 group .These data suggest that HIF-1α induced the upregulation of survivin in the early stage of DR. Survivin contributed to the development and progression of DR through the HIF-1α pathway and become an important progression marker of DR.

Assessment of endogenous reference gene suitability for serum exosomal microRNA expression analysis in liver carcinoma resection studies

Serum exosomal microRNAs (miRNAs) have received considerable attention as potential biomarkers for tumor diagnosis. Reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) is commonly used to detect miRNA expression levels in various types of cancer. One prerequisite for valid RT‑qPCR data is the correct normalization of miRNAs to stably expressed endogenous reference genes (RGs). The study of liver carcinoma resection requires the use of reliable RGs in order to assess the expression levels of serum exosomal target miRNAs. However, the assessment of RG suitability for optimum serum exosomal miRNA expression analysis has yet to be investigated. The present study investigated the expression stability of 10 candidate RGs. The candidate genes included eight miRNAs (miR‑16, miR‑103, miR‑191, let‑7a, miR‑26a, miR‑221, miR‑181a, and miR‑451) and two small RNAs (5S and U6). The stability values of the candidate genes were calculated using the following algorithms: geNorm, NormFinder, BestKeeper, and the comparative ΔCt method. The overall ranking obtained from these analyses revealed that miR‑221, let‑7a, and miR‑26a were appropriate internal RGs for analysis of serum miRNAs in patients with hepatocellular carcinoma. In addition, normalization with miR‑221 and let‑7a combined, as recommended by geNorm, or with miR‑26a, as recommended by NormFinder, increased the accuracy of interpretation of the target miRNA expression levels in hepatopathy studies.

HIF-1α contributes to proliferation and invasiveness of neuroblastoma cells via SHH signaling

The aim of this study was to investigate the effects of hypoxia-inducible factor-1α (HIF-1α) on the proliferation, migration and invasion of neuroblastoma (NB) cells and the mechanisms involved. We here initially used the real-time polymerase chain reaction (real-time PCR), Western blotting and immunohistochemistry (IHC) to detect the expression of HIF-1α and components of the sonic hedgehog (SHH) signaling pathway in NB cells and human specimens. Subsequently, cell proliferation, migration and invasion were analyzed using the cell counting assay, wound healing assay and Transwell system in two types of human NB cell lines, SH-SY5Y and IMR32. In addition, the role of HIF-1α in NB cells growth was determined in a xenograft nude mouse model. We found that the level of HIF-1α was significantly upregulated during NB progression and was associated with the expression of two components of SHH signaling, SHH and GLI1. We next indicated that the proliferation, migration and invasiveness of SH-SY5Y and IMR32 cells were significantly inhibited by HIF-1α knockdown, which was mediated by small interfering RNAs (siRNAs) targeting against its mRNA. Furthermore, the growth of NB cells in vivo was also suppressed by HIF-1α inhibition. Finally, the pro-migration and proliferative effects of HIF-1α could be reversed by disrupting SHH signaling. In conclusion, our results demonstrated that upregulation of HIF-1α in NB promotes proliferation, migration and invasiveness via SHH signaling.

TGF-β Regulates Survivin to Affect Cell Cycle and the Expression of EGFR and MMP9 in Glioblastoma

Transforming growth factor beta (TGF-β) is suggestive of a molecular target for cancer therapy due to its involvement in cell cycle, differentiation, and morphogenesis. Meanwhile, survivin is identified as an apoptosis inhibitor and involved in tumorgenesis. Here, we aimed to investigate the potential associations between TGF-β and survivin in glioblastoma U87 cell line. Survivin small interfering RNA (siRNA), Western blotting, and cell cycle analysis were introduced to detect relevant proteins in TGF-β pathways. In this study, we observed a concentration- and time-dependent increase of survivin expression after treatment with TGF-β1. However, the kinase inhibitors U0126 and LY294002 inhibited the upregulation of survivin in comparison with DMSO. In addition, survivin siRNA effectively abrogated survivin expression in U87 cells, therefore affected cells' entry into the S phase of cell cycle, and then repressed the expression of epidermal growth factor receptor (EGFR) and matrix metalloproteinase 9 (MMP9) in comparison with non-transfection. In conclusion, the present study shows that TGF-β upregulates survivin expression via ERK and PI3K/AKT pathway, leading to glioblastoma cell cycle progression. Thus, the blockade of survivin will allow for the treatment of glioblastoma, partially attributing to the inhibition of EGFR and MMP9 expression.

Myricanol induces apoptotic cell death and anti-tumor activity in non-small cell lung carcinoma in vivo

This study explored the inhibiting effect and mechanism of myricanol on lung adenocarcinoma A549 xenografts in nude mice. Forty nude mice with subcutaneous A549 xenografts were randomly divided into five groups: high-dose myricanol (40 mg/kg body weight) group; middle-dose myricanol (20 mg/kg body weight) group; low-dose myricanol (10 mg/kg body weight) group; polyethylene glycol 400 vehicle group (1 mL/kg); and tumor model group. Nude mice were sacrificed after 14 days of treatment and the tumor inhibition rate (TIR, %) was then calculated. The relative mRNA expression levels of Bax, Bcl-2, VEGF, HIF-1α, and survivin in the tumor tissues were determined by real-time PCR. TUNEL assay was applied to determine cellular apoptosis, while IHC test was performed to detect the protein expression levels of Bax, Bcl-2, VEGF, HIF-1α, and survivin. The TIR of the three myricanol-treated groups ranged from 14.9% to 38.5%. The IHC results showed that the protein expression of Bcl-2, VEGF, HIF-1α, and survivin were consistently downregulated, whereas that of Bax was upregulated after myricanol treatment. Myricanol also significantly upregulated the mRNA expression of Bax and downregulated that of Bcl-2, VEGF, HIF-1α, and survivin in a dose-dependent manner (p < 0.05 to 0.001). These results are consistent with those of IHC. The TUNEL assay results indicated that apoptotic-positive cells significantly increased in the myricanol-treated tumor tissues compared with the cells of the vehicle control group (p < 0.01 to 0.001). These data suggest that myricanol could significantly decelerate tumor growth in vivo by inducing apoptosis.

HIF-1α induces VE-cadherin expression and modulates vasculogenic mimicry in esophageal carcinoma cells

AIM

To investigate whether hypoxia inducible factor (HIF)-1α modulates vasculogenic mimicry (VM) by upregulating VE-cadherin expression in esophageal squamous cell carcinoma (ESCC).

METHODS

Esophageal squamous cancer cell lines Eca109 and TE13 were transfected with plasmids harboring small interfering RNAs targeting HIF-1α or VE-cadherin. The proliferation and invasion of esophageal carcinoma cells were detected by MTT and Transwell migration assays. The formation of tubular networks of cells was analyzed by 3D culture in vitro. BALB/c nude mice were used to observe xenograft tumor formation. The relationship between the expression of HIF-1α and VE-cadherin, ephrinA2 (EphA2) and laminin5γ2 (LN5γ2) was measured by Western blot and real-time polymerase chain reaction.

RESULTS

Knockdown of HIF-1α inhibited cell proliferation (32.3% ± 6.1% for Eca109 cells and 38.6% ± 6.8% for TE13 cells, P < 0.05). Both Eca109 and TE13 cells formed typical tubular networks. The number of tubular networks markedly decreased when HIF-1α or VE-cadherin was knocked down. Expression of VE-cadherin, EphA2 and LN5γ2 was dramatically inhibited, but the expression of matrix metalloproteinase 2 had no obvious change in HIF-1α-silenced cells. Knockdown of VE-cadherin significantly decreased expression of both EphA2 and LN5γ2 (P < 0.05), while HIF-1α expression was unchanged. The time for xenograft tumor formation was 6 ± 1.2 d for Eca109 cells and Eca109 cells transfected with HIF-1α Neo control short hairpin RNA (shRNA) vector, and 8.4 ± 2.1 d for Eca109 cells transfected with an shRNA against HIF-1α. Knockdown of HIF-1α inhibited vasculogenic mimicry (VM) and tumorigenicity in vivo.

CONCLUSION

HIF-1α may modulate VM in ESCC by regulating VE-cadherin expression, which affects VM formation through EphA2 and LN5γ2.

Maslinic acid induces mitochondrial apoptosis and suppresses HIF-1α expression in A549 lung cancer cells under normoxic and hypoxic conditions

The apoptotic effects of maslinic acid (MA) at 4, 8, 16, 32 and 64 μmol/L on human lung cancer A549 cells under normoxic and hypoxic conditions were examined. MA at 4–64 and 16–64 μmol/L lowered Bcl-2 expression under normoxic and hypoxic conditions, respectively (p < 0.05). This agent at 4–64 μmol/L decreased Na⁺-K⁺-ATPase activity and increased caspase-3 expression under normoxic conditions, but at 8–64 μmol/L it caused these changes under hypoxic conditions (p < 0.05). MA up-regulated caspase-8, cytochrome c and apoptosis-inducing factor expression under normoxic and hypoxic conditions at 8–64 μmol/L and 32–64 μmol/L, respectively (p < 0.05). MA down-regulated hypoxia-inducible factor (HIF)-1α, vascular endothelial growth factor (VEGF), survivin and inducible nitric oxide synthase (iNOS) expression under normoxic and hypoxic conditions at 8–64 and 16–64 μmol/L, respectively (p < 0.05). After cells were pre-treated with YC-1, an inhibitor of HIF-1α, MA failed to affect the protein expression of HIF-1α, VEGF, survivin and iNOS (p > 0.05). MA at 8-64 and 32-64 μmol/L reduced reactive oxygen species and nitric oxide levels under both conditions (p < 0.05). These findings suggest that maslinic acid, a pentacyclic triterpenic acid, exerted its cytotoxic activities toward A549 cells by mediating mitochondrial apoptosis and the HIF-1α pathway.

SDF-1/CXCR4 signaling up-regulates survivin to regulate human sacral chondrosarcoma cell cycle and epithelial-mesenchymal transition via ERK and PI3K/AKT pathway

Human sacral chondrosarcoma, the most common one of malignant tumors, has a potent capacity to invade locally and metastasize. Notably, CXCR4 and survivin are widely recommended as a candidate of the molecule-targeted therapy. However, the roles and associations of CXCR4 and survivin in sacral chondrosarcoma have not been well characterized. Here, we investigated CXCR4 and survivin expression in human sacral chondrosarcoma. Resected sacral chondrosarcoma specimens were available from 30 patients. In vitro human chondrosarcoma cell lines SW1353 was used. Immunohistochemistry, Western blot, RNA interference, and cell cycle analyses were conducted. Immunohistochemistry revealed that CXCR4 and survivin expressed in 83.3 and 86.7 % of sacral chondrosarcoma tissues, respectively, and both were closely associated with grade and recurrence (p < 0.05). Western blot revealed that survivin expression in SW1353 increased in a dose- and time-dependent manner following SDF-1 treatment. However, the interference with MEK/ERK and PI3K/AKT pathway affected SDF-1-induced up-regulation of survivin. Besides survivin siRNA affected cell cycle progression and the expression of epithelial-mesenchymal transition (EMT) biomarkers: Snail and N-cadherin, when compared with those of non-transfection. In conclusion, the present study shows that SDF-1/CXCR4 signaling up-regulates survivin via MEK/ERK and PI3K/AKT pathway, leading to cell cycle and EMT occurrence in human sacral chondrosarcoma. The antagonizing of CXCR4 and/or survivin might benefit patients with sacral chondrosarcoma.

SDF-1/CXCR4 Axis Regulates Cell Cycle Progression and Epithelial-Mesenchymal Transition via Up-regulation of Survivin in Glioblastoma

Stromal cell-derived factor 1 (SDF-1)/CXCR4 ligand-receptor axis is widely recommended as an attractive target for cancer therapy. Meanwhile, epithelial-mesenchymal transition (EMT) process is linked to disease pathophysiology. As one of inhibitors of apoptosis proteins, survivin is implicated in the onset and development of cancer. In the present study, we tried to determine the cause-effect associations between SDF-1/CXCR4 axis and survivin expression in glioblastoma U-251 cell line. Survivin activation and inhibition were induced with exogenous SDF-1 and survivin small interfering RNA (survivin siRNA), respectively. Western blot was used to detect relevant proteins in SDF-1/CXCR4 axis. Western blot analysis revealed that survivin expression in U-251 increased in a dose- and time-dependent manner in response to SDF-1 treatment. However, the interference with MEK/ERK and PI3K/AKT pathway prohibited SDF-1-induced survivin up-regulation. Importantly, survivin knockdown abrogated cell cycle progression and the expression of snail and N-cadherin, compared with non-transfectants. In conclusion, the present study shows that SDF-1 up-regulates survivin via MEK/ERK and PI3K/AKT pathway, leading to cell cycle progression and EMT occurrence dependent on survivin. The blockade of survivin will allow for the treatment of glioblastoma.

Up-regulation of survivin by AKT and hypoxia-inducible factor 1α contributes to cisplatin resistance in gastric cancer

This study investigated the contribution of survivin and its upstream regulators, AKT and hypoxia-inducible factor 1α (HIF-1α), to the resistance of gastric cancer cells to cisplatin (CDDP). We found that over-expression of survivin increased the resistance of SGC7901 and BGC823 gastric cancer cells to CDDP. Its over-expression abrogated CDDP-induced inhibition of cell proliferation and CDDP-induced cell apoptosis. In contrast, down-regulation of survivin expression using small hairpin RNA (shRNA) vectors and the small-molecule inhibitor YM155, or inhibition of survivin function using a recombinant cell-permeable dominant-negative survivin protein (dNSur9), promoted CDDP-induced apoptosis. CDDP-resistant sub-lines generated from the parental SGC7901 and BGC823 cells by exposure to increasing concentrations of CDDP expressed higher levels of HIF-1α and survivin in response to hypoxia, and higher levels of phosphorylated AKT (pAKT). Specific inhibition of AKT reduced the expression of HIF-1α and survivin, whereas specific inhibition or depletion of HIF-1α reduced survivin expression but had no effect on the expression of phosphorylated AKT. The expression levels of survivin affected the therapeutic efficacy of CDDP in treating gastric tumors in mice. Specific inhibition of survivin, AKT and HIF-1α enhanced the sensitivity of CDDP-resistant cells to CDDP. Specific inhibition of survivin, AKT and HIF-1α synergized with CDDP to suppress the growth of gastric tumors that had been engineered to overexpress survivin. In summary, the results provide evidence that up-regulation of survivin by AKT and HIF-1α contributes to CDDP resistance, indicating that inhibition of these pathways may be a potential strategy for overcoming CDDP resistance in the treatment of gastric cancer.