Silencing of HIF-1alpha suppresses tumorigenicity of renal cell carcinoma through induction of apoptosis

Neferine increases sensitivities to multiple anticancer drugs via downregulation of Bcl-2 expression in renal cancer cells

BACKGROUND

Neferine is the major alkaloid extracted from a seed embryo of Nelumbo nucifera and shows cytotoxic effects in various human cancer cells. However, no detailed studies have been reported on its antitumor efficacy of a combinational treatment in human renal cancer cells.

OBJECTIVE

This study evaluated the antitumor effects of a combination therapy of neferine and various drugs on renal cancer Caki-1 cells.

METHODS

Flow cytometry analysis was performed to evaluate the cell cycle analysis and apoptosis, respectively. Western blotting and reverse transcription polymerase chain reaction were performed to analyze the effect of neferine on the expression of apoptosis-related genes in Caki-1 cells. In addition, reactive oxygen species (ROS) generation was evaluated using flow cytometry.

RESULTS

Treatment with neferine dose-dependently induces apoptosis and Bcl-2 downregulation in Caki-1 cells. In addition, neferine triggers cell cycle arrest at the G2/M phase in Caki-1 cells. The neferine-induced apoptosis was mediated by ROS generation, and neferine-facilitated Bcl-2 downregulation was regulated at the transcriptional level through the suppression of p65 expression, resulting in inactivation of the NF-κB pathway in Caki-1 cells. The ROS scavenger, N-acetyl-l-cysteine (NAC), intensely reversed the effects of neferine on apoptosis and Bcl-2 downregulation. We determined that neferine markedly potentiates the antitumor effects of multiple anticancer drugs (cisplatin, silybin, and thapsigargin), and those effects can be reversed by Bcl-2 overexpression or NAC pretreatment in Caki-1 cells.

CONCLUSION

These results suggest that neferine can increase chemosensitivities to anticancer drugs via downregulation of Bcl-2 expression through ROS-dependent suppression of the NF-κB signaling pathway in human renal cancer cells.

HIFα independent mechanisms in renal carcinoma cells modulate divergent outcomes in fibronectin assembly mediated by hypoxia and CoCl2

Fibronectin (FN) is a core matrix protein that assembles to form a dynamic cellular scaffold, frequently perturbed during oncogenic transformation. Tumor hypoxia, characterized by low oxygen concentrations in the microenvironment of most solid tumors has been shown to accelerate FN assembly in fibroblasts and cancer-associated fibroblasts, cell types that produce abundant amounts of FN protein. Nevertheless, FN matrix regulation in epithelial cancer cells during hypoxia remains less well defined. In this study we investigate the assembly of the FN matrix during hypoxia in renal cancer epithelial cells, the cells of origin of renal cell carcinoma (RCC). We show that hypoxia (1% O₂) specifically increases matrix disassembly and increases migratory propensity in renal cancer cells. However, HIFα stabilization using hypoxia mimetics, does not recapitulate the effect of hypoxia on FN matrix reorganization or cell migration. Using a combination of knockdown and inhibitor-based approaches, our work characterizes the signaling events that mediate these two disparate changes on the matrix and explores its functional significance on chemotactic cell migration. Our study systematically reexamines the role of hypoxia mimetics as experimental substitutes for hypoxia and provides new findings on HIFα stabilization and the FN matrix in the context of renal cancer.

Metformin Induces Different Responses in Clear Cell Renal Cell Carcinoma Caki Cell Lines

Clear cell renal cell carcinoma (ccRCC) is the most common and lethal form of urological cancer diagnosed globally. Mutations of the von Hippel-Lindau (VHL) tumor-suppressor gene and the resultant overexpression of hypoxia-inducible factor (HIF)-1α protein are considered hallmarks of ccRCC. Persistently activated HIF-1α is associated with increased cell proliferation, angiogenesis, and epithelial–mesenchymal transition (EMT), consequently leading to ccRCC progression and metastasis to other organs. However, the VHL status alone cannot predict the differential sensitivity of ccRCC to cancer treatments, which suggests that other molecular differences may contribute to the differential response of ccRCC cells to drug therapies. In this study, we investigated the response to metformin (an antidiabetic drug) of two human ccRCC cell lines Caki-1 and Caki-2, which express wild-type VHL. Our findings demonstrate a differential response between the two ccRCC cell lines studied, with Caki-2 cells being more sensitive to metformin compared to Caki-1 cells, which could be linked to the differential expression of HIF-1α despite both cell lines carrying a wild-type VHL. Our study unveils the therapeutic potential of metformin to inhibit the progression of ccRCC in vitro. Additional preclinical and clinical studies are required to ascertain the therapeutic efficacy of metformin against ccRCC.

Potential Applications of Nanotechnology in Urological Cancer

Nowadays, the potential scope of nanotechnology in uro-oncology (cancers of the prostate, bladder, and kidney) is broad, ranging from drug delivery, prevention, and diagnosis to treatment. Novel drug delivery methods using magnetic nanoparticles, gold nanoparticles, and polymeric nanoparticles have been investigated in prostate cancer. Additionally, renal cancer treatment may be profoundly influenced by applications of nanotechnology principles. Various nanoparticle-based strategies for kidney cancer therapy have been proposed. Partly due to the dilution of drug concentrations by urine production, causing inadequate drug delivery to tumor cells in the treatment of bladder cancer, various multifunctional bladder-targeted nanoparticles have been developed to enhance therapeutic efficiency. In each of these cancer research fields, nanotechnology has shown several advantages over widely used traditional methods. Different types of nanoparticles improve the solubility of poorly soluble drugs, and multifunctional nanoparticles have good specificity toward prostate, renal, and bladder cancer. Moreover, nanotechnology can also combine with other novel technologies to further enhance effectivity. As our understanding of nanotechnologies grows, additional opportunities to improve the diagnosis and treatment of urological cancer are excepted to arise. In this review, we focus on nanotechnologies with potential applications in urological cancer therapy and highlight clinical areas that would benefit from nanoparticle therapy.

Chloroquine potentiates the anticancer effect of sunitinib on renal cell carcinoma by inhibiting autophagy and inducing apoptosis

Sunitinib based adjuvant chemotherapy combined with chloroquine (CQ) for the treatment of renal cell carcinoma (RCC) is in clinical trials; however, its anti-RCC effect and the mechanism remain unclear. In the present study, the anti-RCC effect of sunitinib with CQ and the underlying mechanism was investigated. An MTT assay demonstrated that CQ enhanced the proliferation inhibitory effect of sunitinib against the OS-RC-2 RCC cell line. CQ inhibited sunitinib-induced autophagy in OS-RC-2, which was evidenced by the inhibition of autophagic vacuoles, acidic vesicular organelle formation, light chain 3 (LC3)-II recruitment to the autophagosomes and the conversion of LC3-I to LC3-II, as induced by sunitinib. The inhibition of autophagy by CQ enhanced sunitinib-induced apoptosis, which was characterized by the activation of caspase-3, caspase-9, Bcl-2 and p53. Additionally, the exposure of OS-RC-2 cells to CQ and sunitinib resulted in the inhibition of AKT, tuberous sclerosis complex 2, mechanistic target of rapamycin and p70 ribosomal S6 kinase, which are associated with cell proliferation. In in vivo study, a combination of sunitinib with CQ in mice significantly reduced OS-RC-2 cell xenograft growth compared with the sunitinib alone group. In conclusion, the present study demonstrated that CQ may enhance the anti-RCC effect of sunitinib by inhibiting the autophagy induced by sunitinib, and enhance the rate of apoptosis. Inhibiting cell proliferation may also serve a role in the synergistic antitumor effect of sunitinib and CQ. These data suggest that combination therapy of sunitinib with CQ may be a promising strategy for adjuvant chemotherapy in RCC.

High Altitude and Cancer Mortality

Thiersch, Markus, and Erik R. Swenson. High altitude and cancer mortality. High Alt Med Biol 19:116-123, 2018.-Humans living at high altitude (HA) are exposed to chronic (hypobaric) hypoxia. Despite the permanent stress of hypoxic exposure, humans populating HA areas have reduced cancer mortality over a broad spectrum of cancer types. In fact, the majority of the physiological adaptive processes at HA occurring in response to hypoxia might be the driving force for reduced cancer mortality at HA. In this review, we summarize epidemiological and animal studies that compare cancer incidence and cancer mortality between HA and low altitude or between hypoxia and normoxia, respectively. We discuss the potential role of oxygen-independent and oxygen-dependent mechanisms that might contribute to reduced cancer mortality at HA. Reactive oxygen species and their detoxification as well as the hypoxia-inducible factors are especially promising targets and may be related to why cancer mortality is reduced at HA. In addition, we briefly discuss two aspects with a proven impact on tumorigenesis, namely the immune system and tumor surveillance as well as HA-induced metabolic changes. Further animal and clinical studies are clearly needed to explain why cancer mortality is reduced at HA and to decide whether HA or hypoxia-based therapeutic approaches could be implemented for cancer treatment. However, exposure to HA activates multiple adaptive mechanisms (oxygen independent and oxygen dependent) sharing common pathways as well as activating counteracting pathways, which complicate the identification of specific HA-induced mechanisms of tumor suppression.

Regulation of the hypoxic tumor environment in hepatocellular carcinoma using RNA interference

Objectives

Hypoxia is the condition where tumor cells have been deprived of oxygen and has been shown to have a role of tumor development in the hepatocellular carcinoma (HCC).

Methods

Using PubMed online database and Google scholar web site, the terms “angiogenesis”, “apoptosis”, “RNA interference” and/or “hepatocellular carcinoma (HCC)” were searched and analyzed.

Results

The hypoxia inducible factors (HIFs) are transcriptional regulators that affect a homeostatic response to oxidative stress and have been identified as a key transcription activator of angiogenesis, survival, and metabolism. Cytokines, such as IL-8, also controlled endothelia cells survival and angiogenesis. IL-8 was also overexpressed under hypoxia and induced tumor angiogenesis and growth.

Conclusion

Therefore, regulation of HIFs and IL-8 controlled the tumor microenvironment in terms of tumor angiogenesis and apoptosis. The review summarizes the results of regulation of the hypoxic tumor environment.

WSB1 promotes tumor metastasis by inducing pVHL degradation

In this study, Kim et al. identified WD repeat and SOCS box-containing protein 1 (WSB1) as a novel regulator of pVHL through WSB1's E3 ligase activity. These findings provide important new insights into the understanding of misregulation of the pVHL–HIF pathway in cancer cell invasion and metastasis.

The von Hippel-Lindau tumor suppressor pVHL is an E3 ligase that targets hypoxia-inducible factors (HIFs). Mutation of VHL results in HIF up-regulation and contributes to processes related to tumor progression such as invasion, metastasis, and angiogenesis. However, very little is known with regard to post-transcriptional regulation of pVHL. Here we show that WD repeat and SOCS box-containing protein 1 (WSB1) is a negative regulator of pVHL through WSB1's E3 ligase activity. Mechanistically, WSB1 promotes pVHL ubiquitination and proteasomal degradation, thereby stabilizing HIF under both normoxic and hypoxic conditions. As a consequence, WSB1 up-regulates the expression of HIF-1α’s target genes and promotes cancer invasion and metastasis through its effect on pVHL. Consistent with this, WSB1 protein level negatively correlates with pVHL level and metastasis-free survival in clinical samples. This work reveals a new mechanism of pVHL's regulation by which cancer acquires invasiveness and metastatic tendency.

The role of HIF1α in renal cell carcinoma tumorigenesis

The transcription factor HIF1α is implicated in the development of clear cell renal cell carcinoma (ccRCC). Although HIF1α was initially believed to be essential for ccRCC development, recent studies hypothesize an oncogenic role for HIF2α in ccRCC, but a tumor suppressor role for HIF1α, leading to uncertainty as to the precise roles of the different HIF transcription factors in this disease. Using evidence available from studies with human ccRCC cell lines, mouse xenografts, murine models of ccRCC, and human ccRCC specimens, we evaluate the roles of HIF1α and HIF2α in the pathogenesis of ccRCC. We present a convergence of clinical and mechanistic data supporting an important role for HIF1α in promoting tumorigenesis in a clinically important and large subset of ccRCC. This indicates that current understanding of the exact roles of HIF1α and HIF2α is incomplete and that further research is required to determine the diverse roles of HIF1α and HIF2α in ccRCC.

KEY MESSAGES

The TRACK mouse ccRCC model with constitutively active HIF1α but not HIF2α expressed in proximal tubules develops RCC. HIF1α protein is expressed in the majority of human ccRCC specimens. Elevated HIF1α in ccRCC correlates with a worse prognosis. Many publications do not support a tumor suppressor role for HIF1α in ccRCC. HIF1α, but not HIF2α, is expressed in some types of cancer stem cells.

Inhibition of phosphoinositide 3-kinase/Akt pathway decreases hypoxia inducible factor-1α expression and increases therapeutic efficacy of paclitaxel in human hypoxic gastric cancer cells

The phosphatidylinositol-3-kinase (PI3K)/Akt signaling pathway plays an important role in cell proliferation, transformation, apoptosis, tumor growth and angiogenesis. Paclitaxel is commonly used to treat multiple human malignancies; however, the underlying mechanisms of paclitaxel in gastric cancer (GC) have not been fully investigated. In the present study, specimens from 45 GC and 36 chronic gastritis patients were collected, and the correlations of PI3K, phosphorylated-Akt (p-Akt) and hypoxia-inducible factor-1α (HIF-1α) expression with the clinicopathological characteristics of GC were analyzed by immunohistochemistry. The human SGC-7901 GC cells under hypoxic conditions were pretreated with the PI3K inhibitor, LY294002 (40 μM), and paclitaxel (0.1 μM). The expression levels of PI3K, p-Akt and HIF-1α were detected by quantitative polymerase chain reaction and western blotting. Cell proliferative activity and apoptosis were evaluated by the Cell Counting Kit-8 assay and flow cytometry. As a result, the rates of positive expression of PI3K, p-Akt and HIF-1α were significantly higher in GC compared with chronic gastritis patients (each P<0.01), and were positively associated with the tumor-node-metastasis (TNM) staging, lymph node metastases, lymphatic infiltration and vascular infiltration (each P<0.01), but inversely correlated with tumor differentiation (P<0.01) in patients with GC. Under hypoxic conditions, the combined inhibition of the PI3K/Akt pathway with paclitaxel markedly reduced the proliferative activity and induced cell apoptosis in GC cells compared with the single treatment of PI3K inhibitor or paclitaxel (each P<0.01), and was accompanied by a decreased expression of HIF-1α. Overall, our findings indicate that the increased expression of the PI3K/Akt/HIF-1α pathway was closely correlated with tumor differentiation, TNM staging, lymph node metastases and lymphatic and vascular infiltration. The inhibition of the PI3K/Akt pathway enhanced the therapeutic efficacy of paclitaxel in GC cells under hypoxic conditions, suggesting that the PI3K/Akt/HIF-1α pathway may act as an important therapeutic target for paclitaxel treatment of GC.

HIF-1α silencing suppresses growth of lung adenocarcinoma A549 cells through induction of apoptosis

Lung adenocarcinoma (AC) is one of the most deadly malignancies. The disease has a low five-year survival rate; therefore, the identification of novel therapeutic agents is required. This study aimed to investigate the effect of small interfering RNA (siRNA) targeting hypoxia‑inducible factor 1α (HIF‑1α) on the growth of AC A549 cells. A549 cells were transfected with various concentrations of HIF‑1α or control siRNA, and the effect on HIF‑1α expression was analyzed using quantitative polymerase chain reaction and western blot analysis. The effects of HIF-1α siRNA on growth inhibition and apoptosis were then assessed using standard methods. HIF‑1α siRNA treatment significantly reduced HIF‑1α mRNA and protein expression in A549 cells. Furthermore, the downregulation of HIF-1α expression inhibited the growth of A549 cells and induced apoptosis of A549 cells by upregulating caspase-3 expression. The present in vitro study demonstrates that the downregulation of HIF‑1α is capable of suppressing AC A549 cell growth, through the induction of apoptosis. This suggests that HIF‑1α inhibition may represent a promising strategy for the treatment of AC.

HIF-1α of bone marrow endothelial cells implies relapse and drug resistance in patients with multiple myeloma and may act as a therapeutic target

PURPOSE

To investigate the role of hypoxia-inducible factor-1α (HIF-1α) in angiogenesis and drug resistance of bone marrow endothelial cells of patients with multiple myeloma.

EXPERIMENTAL DESIGN

HIF-1α mRNA and protein were evaluated in patients with multiple myeloma endothelial cells (MMEC) at diagnosis, at relapse after bortezomib- or lenalidomide-based therapies or on refractory phase to these drugs, at remission; in endothelial cells of patients with monoclonal gammapathies of undetermined significance (MGUS; MGECs), and of those with benign anemia (controls). The effects of HIF-1α inhibition by siRNA or panobinostat (an indirect HIF-1α inhibitor) on the expression of HIF-1α proangiogenic targets, on MMEC angiogenic activities in vitro and in vivo, and on overcoming MMEC resistance to bortezomib and lenalidomide were studied. The overall survival of the patients was also observed.

RESULTS

Compared with the other endothelial cell types, only MMECs from 45% of relapsed/refractory patients showed a normoxic HIF-1α protein stabilization and activation that were induced by reactive oxygen species (ROS). The HIF-1α protein correlated with the expression of its proangiogenic targets. The HIF-1α inhibition by either siRNA or panobinostat impaired the MMECs angiogenesis-related functions both in vitro and in vivo and restored MMEC sensitivity to bortezomib and lenalidomide. Patients with MMECs expressing the HIF-1α protein had shorter overall survival.

CONCLUSIONS

The HIF-1α protein in MMECs may induce angiogenesis and resistance to bortezomib and lenalidomide and may be a plausible target for the antiangiogenic management of patients with well-defined relapsed/refractory multiple myeloma. It may also have prognostic significance.

Human telomerase reverse-transcriptase promoter-controlled and herpes simplex virus thymidine kinase-armed adenoviruses for renal cell carcinoma treatment

New treatment strategies are required for renal cell carcinoma (RCC) due to its relative insensitivity to conventional radio- and chemotherapies. The promising strategy of tumor inhibition using human telomerase reverse transcriptase (hTERT)-controlled herpes simplex virus thymidine kinase/ganciclovir (HSV-TK/GCV) in the hTERT promoter-driven HSV-TK/GCV suicide gene system was investigated. Tumor volume, weight, relative proliferation rate, and cell-apoptosis levels were examined in mice injected with adenovirus (Ad)-hTERT-HSV-TK and GCV. Increased cell death occurred following treatment with Ads carrying hTERT-HSV-TK/GCV or cytomegalovirus promoter-controlled (CMV)-HSV-TK/GCV for human RCC 786-0 and fibroblast MRC-5 cells. In mice, Ad-hTERT-HSV-TK/GCV more specifically inhibited tumor and RCC xenograft growth than Ad-CMV-HSV-TK/GCV (P < 0.05). Furthermore, Ad-hTERT-HSV-TK/GCV did not significantly damage normal fibroblasts or organ systems (heart, lung, liver, brain, kidney, and spleen). Thus, Ad-hTERT-HSV-TK/GCV is an effective RCC inhibitor in human cells in vitro and in vivo mouse models, indicating potential usefulness in RCC-targeted gene therapy.

Angiotensin II type 1 receptor antagonist prevents hepatic carcinoma in rats with nonalcoholic steatohepatitis

BACKGROUND

Angiotensin II type 1 receptor blockers (ARBs) have been reported to attenuate hepatic fibrosis in non-alcoholic steatohepatitis (NASH). However, it is uncertain whether ARBs prevent hepatocarcinogenesis in NASH even after hepatic fibrosis has developed.

METHODS

Male Wistar rats were fed with a choline-deficient, L-amino acid-defined (CDAA) diet for 24 weeks, and then fed with the CDAA diet with telmisartan (2 mg/kg/day), a novel ARB, or vehicle for another 24 weeks. The liver histology and the expression of genes and proteins related to angiogenesis were investigated.

RESULTS

The 24-week CDAA diet induced liver cirrhosis. The 48-week CDAA diet exacerbated liver cirrhosis, and developed hepatocellular carcinoma (HCC) in 54.6 % of the rats concurrently with increases of hypoxia-inducible factor-1α (HIF-1α) protein and vascular endothelial growth factor (VEGF) mRNA, which are potent angiogenic factors in the liver. Telmisartan inhibited hepatic fibrosis and preneoplastic lesions and prevented the development of HCC along with inducing decreases in HIF-1α protein and VEGF mRNA.

CONCLUSIONS

These data indicated that telmisartan may prevent hepatocarcinogenesis through the inhibition of hepatic angiogenesis even after liver cirrhosis has been established.

Antiangiogenic agents increase breast cancer stem cells via the generation of tumor hypoxia

Antiangiogenic therapy has been thought to hold significant potential for the treatment of cancer. However, the efficacy of such treatments, especially in breast cancer patients, has been called into question, as recent clinical trials reveal only limited effectiveness of antiangiogenic agents in prolonging patient survival. New research using preclinical models further suggests that antiangiogenic agents actually increase invasive and metastatic properties of breast cancer cells. We demonstrate that by generating intratumoral hypoxia in human breast cancer xenografts, the antiangiogenic agents sunitinib and bevacizumab increase the population of cancer stem cells. In vitro studies revealed that hypoxia-driven stem/progenitor cell enrichment is primarily mediated by hypoxia-inducible factor 1α. We further show that the Akt/β-catenin cancer stem cell regulatory pathway is activated in breast cancer cells under hypoxic conditions in vitro and in sunitinib-treated mouse xenografts. These studies demonstrate that hypoxia-driven cancer stem cell stimulation limits the effectiveness of antiangiogenic agents, and suggest that to improve patient outcome, these agents might have to be combined with cancer stem cell-targeting drugs.

Hypoxia, stem cells and bone tumor

Normal oxygen level is critical for niches that together with other components of the niche play vital role in regulating stem or tumor cells behavior. Hypoxia plays an important role in normal development and disease progression, including the growth of solid tumors. The hypoxia inducible factors (HIFs) are the key mediators of the cellular response to hypoxia. In this review, we focused on the role of HIFs on bone tumor formation. Further, we also emphasized how hypoxia, stem cells, and its niches regulate the bone tumorigenesis.

Comparative analysis of novel and conventional Hsp90 inhibitors on HIF activity and angiogenic potential in clear cell renal cell carcinoma: implications for clinical evaluation

BACKGROUND

Perturbing Hsp90 chaperone function targets hypoxia inducible factor (HIF) function in a von Hippel-Lindau (VHL) independent manner, and represents an approach to combat the contribution of HIF to cell renal carcinoma (CCRCC) progression. However, clinical trials with the prototypic Hsp90 inhibitor 17-AAG have been unsuccessful in halting the progression of advanced CCRCC.

METHODS

Here we evaluated a novel next generation small molecule Hsp90 inhibitor, EC154, against HIF isoforms and HIF-driven molecular and functional endpoints. The effects of EC154 were compared to those of the prototypic Hsp90 inhibitor 17-AAG and the histone deacetylase (HDAC) inhibitor LBH589.

RESULTS

The findings indicate that EC154 is a potent inhibitor of HIF, effective at doses 10-fold lower than 17-AAG. While EC154, 17-AAG and the histone deacetylase (HDAC) inhibitor LBH589 impaired HIF transcriptional activity, CCRCC cell motility, and angiogenesis; these effects did not correlate with their ability to diminish HIF protein expression. Further, our results illustrate the complexity of HIF targeting, in that although these agents suppressed HIF transcripts with differential dynamics, these effects were not predictive of drug efficacy in other relevant assays.

CONCLUSIONS

We provide evidence for EC154 targeting of HIF in CCRCC and for LBH589 acting as a suppressor of both HIF-1 and HIF-2 activity. We also demonstrate that 17-AAG and EC154, but not LBH589, can restore endothelial barrier function, highlighting a potentially new clinical application for Hsp90 inhibitors. Finally, given the discordance between HIF activity and protein expression, we conclude that HIF expression is not a reliable surrogate for HIF activity. Taken together, our findings emphasize the need to incorporate an integrated approach in evaluating Hsp90 inhibitors within the context of HIF suppression.

High expression of p300 in HCC predicts shortened overall survival in association with enhanced epithelial mesenchymal transition of HCC cells

P300 impacts the transcription of several genes involved in biological behavior of human malignancies including hepatocellular carcinomas (HCC). We found p300 is highly expressed in 47% of surgically resected HCC specimens by immunohistochemistry, which correlated with advanced TNM staging (P = 0.034), vascular invasion (P = 0.036), intrahepatic metastasis (P = 0.001) and shortened overall survival (P = 0.028). In vitro study, knocking down of p300 expression in hepatoma cells recovered E-cadherin expression, inhibited the translocation of beta (β)-catenin into the nuclei, decreased cyclin D1 activity and suppressed the migration/invasion of HCC cells. Furthermore, suppression of p300 led to down-regulation of epithelial-mesenchymal transition (EMT)-related molecules such as Snail, Twist and HIF-1 alpha. These observations suggest that p300 contributes to the EMT-related progression of HCCs.

Comparisons of three polyethyleneimine-derived nanoparticles as a gene therapy delivery system for renal cell carcinoma

Background

Polyethyleneimine (PEI), which can interact with negatively charged DNA through electrostatic interaction to form nanocomplexes, has been widely attempted to use as a gene delivery system. However, PEI has some defects that are not fit for keeping on gene expression. Therefore, some modifications against PEI properties have been done to improve their application value in gene delivery. In this study, three modified PEI derivatives, including poly(ε-caprolactone)-pluronic-poly(ε-caprolactone) grafted PEI (PCFC-g-PEI), folic acid-PCFC-isophorone diidocyanate-PEI (FA-PEAs) and heparin-PEI (HPEI), were evaluated in terms of their cytotoxicity and transfection efficiency in vitro and in vivo in order to ascertain their potential application in gene therapy.

Methods

MTT assay and a marker GFP gene, encoding green fluorescent protein, were used to evaluate cell toxicity and transfection activity of the three modified PEI in vitro. Renal cell carcinoma (RCC) models were established in BALB/c nude mice inoculated with OS-RC-2 cells to detect the gene therapy effects using the three PEI-derived nanoparticles as gene delivery vehicles. The expression status of a target gene Von Hippel-Lindau (VHL) in treated tumor tissues was analyzed by semiquantitative RT-PCR and immunohistochemistry.

Results

Each of three modified PEI-derived biomaterials had an increased transfection efficiency and a lower cytotoxicity compared with its precursor PEI with 25-kD or 2-kD molecule weight in vitro. And the mean tumor volume was obviously decreased 30% by using FA-PEAs to transfer VHL plasmids to treat mice RCC models. The VHL gene expression was greatly improved in the VHL-treated group. While there was no obvious tumor inhibition treated by PCFC-g-PEI:VHL and HPEI:VHL complexes.

Conclusions

The three modified PEI-derived biomaterials, including PCFC-g-PEI, FA-PEAs and HPEI, had an increased transfection efficiency in vitro and obviously lower toxicities compared with their precursor PEI molecules. The FA-PEAs probably provide a potential gene delivery system to treat RCC even other cancers in future.

Hypoxia and succinate antagonize 2-deoxyglucose effects on glioblastoma

Glioblastoma multiforme (GBM) are highly proliferative brain tumors characterized by a hypoxic microenvironment which controls GBM stem cell maintenance. Tumor hypoxia promotes also elevated glycolytic rate; thus, limiting glucose metabolism is a potential approach to inhibit tumor growth. Here we investigate the effects mediated by 2-deoxyglucose (2-DG), a glucose analogue, on primary GBM-derived cells maintained under hypoxia. Our results indicate that hypoxia protects GBM cells from the apoptotic effect elicited by 2-DG, which raises succinate dehydrogenase activity thus promoting succinate level decrease. As a consequence hypoxia inducible factor-1α (HIF-1α) degradation occurs and this induces GBM cells to acquire a neuronal committed phenotype. By adding succinate these effects are reverted, as succinate stabilizes HIF-1α and increases GBM stem cell fraction particularly under hypoxia, thus preserving the tumor stem cell niche. 2-DG inhibits anaerobic glycolysis altering GBM cell phenotype by forcing tumor cells into mitochondrial metabolism and by inducing differentiation.