Ets-1 and hypoxia inducible factor-1alpha inhibition by angiotensin II type-1 receptor blockade in hormone-refractory prostate cancer

Selective killing of castration-resistant prostate cancer cells by formycin A via the ATF4-CHOP axis

Prostate cancer is initially androgen-dependent but often relapses to an androgen-independent state called castration-resistant prostate cancer (CRPC). Currently approved therapies have limited efficacy against CRPC, highlighting the need for novel therapeutic strategies. To address this need, we conducted a drug screen in our previously established aggressive CRPC cell model. We found that formycin A induced cell death in CRPC model cells but not in parental prostate cancer cells. In addition, formycin A upregulated death receptor 5 through the induction of endoplasmic reticulum stress, activating the "extrinsic" apoptosis pathway in CRPC model cells. Moreover, formycin A showed in vivo antitumor efficacy against CRPC xenografts in castrated nude mice. Thus, our findings highlight the potential of formycin A as a CRPC therapeutic.

Association between 19 medication use and risk of common cancers: A cross-sectional and Mendelian randomisation study

Background

Previous studies have yielded inconsistent results concerning drug use and the risk of cancers. We conducted a large-scale cross-sectional study and a two-sample Mendelian randomisation (MR) study to reveal the causal effect between the use of 19 medications and the risk of four common cancers (breast, lung, colorectal, and prostate).

Methods

We obtained information on medication use and cancer diagnosis from National Health and Nutrition Examination Survey participants. After propensity score matching, we conducted survey-weighted multivariate logistic regression and restricted cubic spline analysis to assess the observed correlation between medication use and cancer while adjusting for multiple covariates. We also performed MR analysis to investigate causality based on summary data from genome-wide association studies on medication use and cancers. We performed sensitivity analyses, replication analysis, genetic correlation analysis, and reverse MR analysis to improve the reliability of MR findings.

Results

We found that the use of agents acting on the renin-angiotensin system was associated with reduced risk of prostate cancer (odds ratio (OR) = 0.42; 95% confidence interval (CI) = 0.27-0.63, P < 0.001), and there was a nonlinear association of 'decrease-to-increase-to-decrease' (P < 0.0001). The random-effects inverse variance weighted (IVW) model-based primary MR analysis (OR = 0.94, 95% CI = 0.91-0.97, P = 0.0007) and replication MR analysis (OR = 0.90, 95% CI = 0.85-0.96, P = 0.0006) both provided robust evidence of the causality of genetic liability for the use of agents acting on the renin-angiotensin system on a decreased risk of prostate cancer.

Conclusions

Our study provides robust evidence that the use of drugs acting on the renin-angiotensin system can reduce prostate cancer risk. Given the high prevalence of prostate cancer, these findings have important implications for drug selection and prostate cancer prevention in patients with cardiovascular disease.

Transcription Factors Leading to High Expression of Neuropeptide L1CAM in Brain Metastases from Lung Adenocarcinoma and Clinical Prognostic Analysis

Background

There is a lack of understanding of the development of metastasis in lung adenocarcinoma (LUAD). This study is aimed at exploring the upstream regulatory transcription factors of L1 cell adhesion molecule (L1CAM) and to construct a prognostic model to predict the risk of brain metastasis in LUAD.

Methods

Differences in gene expression between LUAD and brain metastatic LUAD were analyzed using the Wilcoxon rank-sum test. The GRNdb (http://www.grndb.com) was used to reveal the upstream regulatory transcription factors of L1CAM in LUAD. Single-cell expression profile data (GSE131907) were obtained from the transcriptome data of 10 metastatic brain tissue samples. LUAD prognostic nomogram prediction models were constructed based on the identified significant transcription factors and L1CAM.

Results

Survival analysis suggested that high L1CAM expression was negatively significantly associated with overall survival, disease-specific survival, and prognosis in the progression-free interval (p < 0.05). The box plot indicates that high expression of L1CAM was associated with distant metastases in LUAD, while ROC curves suggested that high expression of L1CAM was associated with poor prognosis. FOSL2, HOXA9, IRF4, IKZF1, STAT1, FLI1, ETS1, E2F7, and ADARB1 are potential upstream transcriptional regulators of L1CAM. Single-cell data analysis revealed that the expression of L1CAM was found significantly and positively correlated with the expression of ETS1, FOSL2, and STAT1 in brain metastases. L1CAM, ETS1, FOSL2, and STAT1 were used to construct the LUAD prognostic nomogram prediction model, and the ROC curves suggest that the constructed nomogram possesses good predictive power.

Conclusion

By bioinformatics methods, ETS1, FOSL2, and STAT1 were identified as potential transcriptional regulators of L1CAM in this study. This will help to facilitate the early identification of patients at high risk of metastasis.

PKM2 under hypoxic environment causes resistance to mTOR inhibitor in human castration resistant prostate cancer

The aim of this study was to explore the efficacy of mTOR inhibitor for castration-resistant prostate cancer (CRPC) under hypoxia. Although under normoxia C4-2AT6, it is a CRPC cell line, expressed elevated pAkt, pS6 and Pyruvate kinase M2 (PKM2) accompanied by elevated HIF-1a expression, 5% hypoxic condition further induced expression of these proteins. These results indicate hypoxic environment elevated PI3K/Akt/mTOR pathway in aggressive prostate cancer. However, C4-2AT6 cells treated with mTOR inhibitor under hypoxia less decreased compared to cells treated with the same dose drugs under normoxia. Western blot analysis showed mTOR inhibitor: RAD001 not only inhibited pS6, but also increased the expression of PKM2 in a dose and time dependent manner. Pyruvate kinase acts on glycolysis. PKM2, which is frequently express in tumor cells, is one isoform of pyruvate kinase. PKM2 is reported to act as a transcription factor. In the present study overexpression of PKM2 in C4-2AT6 induced resistance to RAD001 under normoxia. To evaluate the therapeutic effect of targeting PKM2, we inhibited PKM2 in C4-2AT6 under hypoxia using si-PKM2. The number of C4-2AT6 under chronic hypoxia exposed to siPKM2 significantly decreased compared to intact C4-2AT6 under chronic hypoxia. Furthermore, si-PKM2 improved resistance to mTOR inhibitor in C4-2AT6. When examined using clinical samples, high PKM2 expression was correlated with a high Gleason score and poor PSA free survival. These results suggested that up-regulation of PKM2 is one possibility of resistance to mTOR inhibitor in CRPC. And it is possible that PKM2 is a useful therapeutic target of CRPC.

Targeting the renin-angiotensin system to improve cancer treatment: Implications for immunotherapy

Renin-angiotensin system (RAS) inhibitors (RASi)-widely prescribed for the treatment of cardiovascular diseases-have considerable potential in oncology. The RAS plays a crucial role in cancer biology and affects tumor growth and dissemination directly and indirectly by remodeling the tumor microenvironment. We review clinical data on the benefit of RASi in primary and metastatic tumors and propose that, by activating immunostimulatory pathways, these inhibitors can enhance immunotherapy of cancer.

KSHV LANA upregulates the expression of epidermal growth factor like domain 7 to promote angiogenesis

Kaposi’s sarcoma (KS) is a highly-vascularized tumor characterized by inflammation and extensive neo-angiogenesis. The KS tumor microenvironment is rich in inflammatory and pro-angiogenic cytokines. Here, we report that the expression of Epidermal growth factor-like domain 7 (EGFL7) is upregulated in Kaposi’s sarcoma-associated herpes virus (KSHV) infected cells. EGFL7 is a secreted pro-angiogenic cytokine that has been implicated in angiogenesis and the proliferation of endothelial cells during many pathological conditions. Our data show that KS tumors as well as primary effusion lymphoma cells have increased levels of EGFL7 compared to the uninfected cells. We determined that the expression of a KSHV latent protein, LANA (latency-associated nuclear antigen), is the main viral factor responsible for this upregulation. The modulation of EGFL7 expression by LANA involves sequestration of death domain-associated protein 6 (Daxx) from the EGFL7 promoter. Daxx acts as a suppressor of promoter activity by binding to the avian erythroblastosis virus E26 oncogene homolog 1 (Ets-1), which is the core transcription factor required for the expression of EGFL7. We additionally show that the upregulation of EGFL7 by LANA contributes to the promotion of angiogenesis since siRNA-mediated knockdown of EGFL7 reduced in vitro tubulogenesis in LANA-expressing HUVEC cells. EGFL7 promotes angiogenesis through autocrine as well as paracrine mechanisms as the supernatant from LANA expressing cells depleted of EGFL7 showed reduced tubulogenesis. This study for the first time demonstrates EGFL7 to be an important angiogenic molecule secreted during KSHV infection that could be exploited for blocking KSHV associated malignancies in conjugation with other anti-angiogenic therapies.

Reactive oxygen species induction by cabazitaxel through inhibiting Sestrin-3 in castration resistant prostate cancer

Reactive oxygen species (ROS) production induced by taxanes in cancer cells may influence the taxane-induced cell death or the drug resistance. We investigated the correlation between the cytotoxic effect of taxanes and ROS production in human castration-resistant prostate cancer (CRPC) cell lines. Three human prostate cancer cell lines were treated with increasing concentrations of docetaxel or cabazitaxel in vitro. Cabazitaxel showed significantly higher cytotoxic efficacy than docetaxel in human CRPC cells, accompanied by elevated ROS production detected by FACS analysis. To investigate whether cabazitaxel-mediated cell death was caused by the ROS generation induced by cabazitaxel, we treated CRPC cells in the presence of antioxidant NAC. NAC reduced the cytotoxic effect induced by cabazitaxel. We found that ROS elimination by Sestrin-3 (SESN3) was significantly inhibited by cabazitaxel, but not by docetaxel. These results indicate higher sensitivity of human CRPC to cabazitaxel compared to docetaxel involves ROS production through inhibiting the expression of antioxidant enzyme SESN3.

Angiotensin Ⅱ induces epithelial-mesenchymal transition in hepatocellular carcinoma cells

AIM

To detect the expression of molecules of the renin-angiotensin system (RAS) in hepatocellular carcinoma (HCC) and explore whether angiotensin Ⅱ (Ang Ⅱ) induces epithelial-mesenchymal transition (EMT) in SSMC7721 cells.

METHODS

Fifty-six HCC tissues were collected, and immunohistochemistry and Western blot were used to assess the expression of angiotensin converting enzyme 1 (ACE1), ACE2, vimentin, E-cadherin proteins in these tissues. Ang II was then used to stimulate SSMC7721 cells to detect whether EMT markers such as vimentin and E-cadherin were induced.

RESULTS

Compared with normal tissues, the expression of ACE1 and AT1 in HCC tumor tissues were higher. Ang II up-regulated the expression of vimentin but down-regulated the expression of E-cadherin in SSMC7721 cells.

CONCLUSION

The RAS may play a role in HCC metastasis.

Angiotensin-(1-7) Suppresses Hepatocellular Carcinoma Growth and Angiogenesis via Complex Interactions of Angiotensin II Type 1 Receptor, Angiotensin II Type 2 Receptor and Mas Receptor

We recently confirmed that angiotensin II (Ang II) type 1 receptor (AT1R) was overexpressed in hepatocellular carcinoma tissue using a murine hepatoma model. Angiotensin(Ang)-(1-7) has been found beneficial in ameliorating lung cancer and prostate cancer. Which receptor of Ang-(1-7) is activated to mediate its effects is much speculated. This study was designed to investigate the effects of Ang-(1-7) on hepatocellular carcinoma, as well as the probable mechanisms. H22 hepatoma-bearing mice were randomly divided into five groups for treatment: mock group, low-dose Ang-(1-7), high-dose Ang-(1-7), high-dose Ang-(1-7) + A779 and high-dose Ang-(1-7) + PD123319. Ang-(1-7) treatment inhibited tumor growth time- and dose-dependently by arresting tumor proliferation and promoting tumor apoptosis as well as inhibiting tumor angiogenesis. The effects of Ang-(1-7) on tumor proliferation and apoptosis were reversed by coadministration with A779 or PD123319, whereas the effects on tumor angiogenesis were completely reversed by A779 but not by PD123319. Moreover, Ang-(1-7) downregulated AT1R mRNA, upregulated mRNA levels of Ang II type 2 receptor (AT2R) and Mas receptor (MasR) and p38-MAPK phosphorylation and suppressed H22 cell-endothelial cell communication. Thus, Ang-(1-7) administration suppresses hepatocellular carcinoma via complex interactions of AT1R, AT2R and MasR and may provide a novel and promising approach for the treatment of hepatocellular carcinoma.

Angiotensin system inhibitors and survival outcomes in patients with metastatic renal cell carcinoma

PURPOSE

The renin-angiotensin system may play a role in carcinogenesis. The purpose of this study was to evaluate the impact of angiotensin system inhibitors (ASI) on outcomes in metastatic renal cell carcinoma (mRCC) patients treated in the targeted therapy era.

EXPERIMENTAL DESIGN

We conducted a pooled analysis of mRCC patients treated on phase II and III clinical trials. Statistical analyses were performed using Cox regression adjusted for several risk factors and the Kaplan-Meier method.

RESULTS

A total of 4,736 patients were included, of whom 1,487 received ASIs and 783 received other antihypertensive agents. Overall, ASI users demonstrated improved overall survival (OS) compared with users of other antihypertensive agents (adjusted HR, 0.838, P = 0.0105, 26.68 vs. 18.07 months) and individuals receiving no antihypertensive therapy (adjusted HR, 0.810, P = 0.0026, 26.68 vs. 16.72 months). When stratified by therapy type, a benefit in OS was demonstrated in ASI users compared with nonusers in individuals receiving VEGF therapy (adjusted HR, 0.737, P < 0.0001, 31.12 vs. 21.94 months) but not temsirolimus or IFNα. An in vitro cell viability assay demonstrated that sunitinib in combination with an ASI significantly decreased RCC cell viability compared with control at physiologically relevant doses. This effect was not observed with either agent alone or with other non-ASI antihypertensives or temsirolimus.

CONCLUSIONS

In the largest analysis to date, we demonstrate that ASI use improved survival in mRCC patients treated in the targeted therapy era. Further studies are warranted to investigate the mechanism underlying this interaction and verify our observations to inform clinical practice.

Lack of an association between angiotensin receptor blocker based therapy and increased risk of cancer: evidence from large observational studies

Background

A previous meta-analysis of randomized controlled studies that were not designed to investigate cancer as a primary outcome suggested that ARB-based therapy is associated with increased risk of cancer; however, results of recent observational studies considering the association have been contradictory. This study sought to evaluate the association between angiotensin receptor blocker (ARB)-based therapy and risk of cancer by conducting a meta-analysis of observational studies.

Methods

Relevant articles published before February 2014 were identified by searching PubMed and the Cochrane Library. Pooled relative risks (RRs) were determined using a random effects model and were used to assess the strength of association between use of ARB-based therapy and risk of cancer.

Results

Six retrospective cohort studies involving a total of 3,827,109 participants and four case-control studies involving a total of 193,029 cases were included. The present study found that ARB-based therapy was not significantly associated with an increased risk of cancer (RR = 0.87, 95%CI: [0.75, 1.01]). However, an analysis including only cohort studies suggested a significantly decreased risk of cancer among individuals with any history of ARB use as compared to those with no history of ARB use (RR = 0.80, 95%CI: [0.55, 0.95]); no significant association was found between ARB use and risk of cancer when the case-control studies were separately considered (RR = 1.03, 95%CI: [0.93, 1.13]). Subgroup analyses showed that use of ARB-based therapy was associated with decreased risk of lung cancer (RR = 0.81, 95%CI: [0.69, 0.94]); however, no significant associations were found with the other cancer sites investigated. Furthermore, no association was observed upon adjustment by type of ARB drug. No publication bias was detected.

Conclusion

Overall, ARB-based therapy was not associated with increased risk of cancer. However, its use may be related to decreased incidence of lung cancer; this finding should be considered carefully and confirmed with further studies.

Is DHT Production by 5α-Reductase Friend or Foe in Prostate Cancer?

The first advance in the history of studies on prostate cancer (PCa) and androgens was the development of treatment with castration and administration of estrogen by Charles B. Huggins, who won the Nobel Prize in Physiology and Medicine. Since then, and for 70 years, androgen deprivation therapy has been the standard therapy for advanced PCa and the center of studies on PCa. However, recent advances have shed light on the relationship between androgens and the development or the progression of PCa. The use of 5AR inhibitors to prevent progression of PCa continues to be widely discussed. Discussion has been fueled by the findings of two large randomized, placebo-controlled trials: the Prostate Cancer Prevention Trial with finasteride and the Reduction by Dutasteride of Prostate Cancer Events trial. Does the development of PCa or progression to castration-resistant PCa depend on dihydrotestosterone (DHT)? Here, we summarize and discuss recent topics of local androgen production of DHT in PCa.

Sunitinib combined with angiotensin-2 type-1 receptor antagonists induces more necrosis: a murine xenograft model of renal cell carcinoma

Background. Angiotensin-2 type-1 receptor antagonists not are only antihypertensive drugs but also can inhibit VEGF production. We hypothesised that adding telmisartan to sunitinib could potentiate the antiangiogenic effects. Material and Methods. 786-O cell lines were injected in nude mice. After tumor development, mice were divided into 4 groups: the first was the control group (DMSO), the second group was treated with sunitinib alone, the third group was treated with telmisartan alone, and the fourth group was treated with the combination. Drugs were orally administered every day for four weeks. Animals were sacrificed after treatment. Blood and tumor tissues were collected for analysis by immunohistochemistry, Western Blot, and ELISA methods. Results. All animals developed a ccRCC and ten in each group were treated. Using a kinetic model, tumors tended to grow slower in the combination group compared to others (P = 0.06). Compared to sunitinib alone, the addition of telmisartan significantly increased tissue necrosis (P = 0.038). Central microvascular density decreased (P = 0.0038) as well as circulating VEGF (P = 0.003). There was no significant variation in proliferation or apoptosis markers. Conclusion. The combination of sunitinib and telmisartan revealed an enhancement of the blockage of the VEGF pathway on renal tumor resulting in a decrease in neoangiogenesis and an increase in necrosis.

Contributions of epithelial-mesenchymal transition and cancer stem cells to the development of castration resistance of prostate cancer

An important clinical challenge in prostate cancer therapy is the inevitable transition from androgen-sensitive to castration-resistant and metastatic prostate cancer. Albeit the androgen receptor (AR) signaling axis has been targeted, the biological mechanism underlying the lethal event of androgen independence remains unclear. New emerging evidences indicate that epithelial-to-mesenchymal transition (EMT) and cancer stem cells (CSCs) play crucial roles during the development of castration-resistance and metastasis of prostate cancer. Notably, EMT may be a dynamic process. Castration can induce EMT that may enhance the stemness of CSCs, which in turn results in castration-resistance and metastasis. Reverse of EMT may attenuate the stemness of CSCs and inhibit castration-resistance and metastasis. These prospective approaches suggest that therapies target EMT and CSCs may cast a new light on the treatment of castration-resistant prostate cancer (CRPC) in the future. Here we review recent progress of EMT and CSCs in CRPC.

Induction of microRNA-138 by pro-inflammatory cytokines causes endothelial cell dysfunction

Exposure to pro-inflammatory cytokines, such as Angiotensin II, endothelin-1 or TNF leads to endothelial dysfunction, characterized by the reduced production of nitric oxide via endothelial nitric oxide synthase (eNOS). We recently identified the Ca(2+) binding protein S100A1 as an essential factor required for eNOS activity. Here we report that pro-inflammatory cytokines down-regulate expression of S100A1 in primary human microvascular endothelial cells (HMVECs) via induction of microRNA-138 (miR-138), in a manner that depends on the stabilization of HIF1-α. We show that loss of S100A1 in ECs reduces stimulus-induced NO production, which can be prevented by inhibition of miR-138. Our study suggests that targeting miR-138 might be beneficial for the treatment of cardiovascular disease.

Human castration resistant prostate cancer rather prefer to decreased 5α-reductase activity

Physiologically relevant steroid 5α-reductase (SRD5A) activity that is essential for dihydrotestosterone (DHT) biosynthesis in human castration-resistant prostate cancer (CRPC) has not been fully characterized yet. In this study to ascertain the potential SRD5A activity, we cultured two human CRPC cell lines, C4-2 and C4-2AT6, with the steroid precursor: ¹³C-[2,3,4]-androstenedione (13C-Adione), and analyzed the sequential biosynthesis of ¹³C-[2,3,4]-testosterone (13C-T) and ¹³C-[2,3,4]-DHT (13C-DHT) by liquid chromatography/mass spectrometry (LC/MS/MS). The 13C-DHT/13C-T concentration ratio detected by LC/MS/MS in C4-2AT6 cells appeared to reflect the SRD5A activity. The ratio in C4-2AT6 was significantly lower than that in C4-2. An increased concentration of DHT did not have a positive effect on cell proliferation, rather it exhibited inhibitory effects. 5α-reductase inhibitors did not have any inhibitory effect at clinically achievable concentrations. These results indicate that CRPC cells may have an unknown regulation system to protect themselves from an androgenic suppressive effect mediated by SRD5A activity.

The role of hypoxia-inducible factor 1α in determining the properties of castrate-resistant prostate cancers

BACKGROUND

Castrate-resistant prostate cancer (CRPC) is a lethal condition in patients receiving androgen deprivation therapy for prostate cancer (PC). Despite numerous studies showing the expression of HIF1α protein under normoxia in PC cell lines, the role of this normoxic HIF1α expression in chemo-resistance and migration has not been investigated previously. As no method is currently available to determine which tumors will progress to CRPC, the role of HIF1α in PC and its potential for predicting the development of CRPC was also investigated.

METHODS

The effect of HIF1α protein knockdown on chemo-resistance and migration of PC3 cells was assessed by cell counting and Transwell assays, respectively. Translation efficiency of HIF1α mRNA was determined in PC cells using a HIF1α 5'UTR-luciferase construct. Clinical outcomes were correlated following the staining of 100 prostate tumors for HIF1α expression.

RESULTS

The CRPC-like cell lines (PC3 and DU145) expressed more HIF1α protein than an androgen sensitive cell line (LNCaP). Migration rate and chemo-resistance were higher in the PC3 cells and both were decreased when HIF1α expression was reduced. Increased translation of HIF1α mRNA may be responsible for HIF1α overexpression in PC3 cells. Patients whose tumors expressed HIF1α had significantly decreased metastasis-free survival and the patients who were on androgen-deprivation therapy had decreased CRPC-free survival on Kaplan-Meier analysis. On multivariate analysis HIF1α was an independent risk factor for progression to metastatic PC (Hazard ratio (HR) 9.8, p = 0.017) and development of CRPC (HR 10.0, p = 0.021) in patients on androgen-deprivation therapy. Notably the tumors which did not express HIF1α did not metastasize or develop CRPC.

CONCLUSIONS

HIF1α is likely to contribute to metastasis and chemo-resistance of CRPC and targeted reduction of HIF1α may increase the responsiveness of CRPCs to chemotherapy. Expression of HIF1α may be a useful screening tool for development of CRPC.

Critical review of cancer risk associated with angiotensin receptor blocker therapy

The role of drugs in new cancer occurrence and cancer-related death is a major concern. Recently, a meta-analysis raised the possibility that angiotensin receptor blockers (ARBs) might have an adverse effect on patients. This generated a significant debate until the publication of two further meta-analyses, neither of which demonstrated an increased risk of new cancer occurrence or cancer-related death with the use of ARBs in patients with hypertension, heart failure, and/or nephropathy. This illustrates that the results of meta-analyses should be interpreted cautiously and critically as bias, such as selection bias, might lead to erroneous conclusions. Overall, the bulk of evidence today indicates that ARBs are not associated with increased cancer risk.

Acquired platinum resistance enhances tumour angiogenesis through angiotensin II type 1 receptor in bladder cancer

BACKGROUND

We investigated the changes in reactive oxygen species (ROS) and angiogenesis through angiotensin II (Ang II) type 1 receptor (AT1R) after the development of acquired platinum resistance in bladder cancer.

METHODS

Four invasive human bladder cancer cell lines, T24, 5637, T24PR, and 5637PR, were used in vitro, whereas in vivo, T24 and T24PR cells were used. T24PR and 5637PR cells were newly established at our institution as acquired platinum-resistant sublines by culturing in cisplatin (CDDP)-containing conditioned medium for 6 months.

RESULTS

Ang II induced significantly higher vascular endothelial growth factor (VEGF) production in T24PR and 5637PR cells than in their corresponding parent cells in vitro, whereas Ang II induced a further increase in VEGF production. These platinum-resistant cells also showed significantly higher AT1R expression than their corresponding parent cells. ROS was also significantly upregulated in T24PR and 5637PR cells, whereas increased AT1R expression was significantly downregulated by scavenging free radicals. We also demonstrated the efficacy of AT1R blockade at suppressing the growth of platinum-resistant xenograft model.

CONCLUSION

Our findings indicate a new molecular mechanism for upregulated AT1R signalling through increased ROS when tumours progressed after the CDDP-based regimens, and shed light on the importance of AT1R blockade for platinum-resistant bladder cancers.

AT1 receptors activation enhances the expression of MMP-2, MMP-13 and VEGF but not MMP-9 in B16F10 melanoma cells

Melanoma is one of the most aggressive cancers of all solid tumors. The effect of angiotensin II on expression of three Matrix Metalloproteinases (MMPs) and Vascular Endothelial Growth Factor (VEGF) in B16F10 melanoma cells was evaluated. Also the blocking effect of losartan on angiotensin II induced effects was assessed. B16F10 murine melanoma cells were cultured in RPMI-1640 medium supplemented with 10% Fetal Bovine Serum (FBS) and 24 h prior to experiment the serum free medium was used. Angiotensin II (0 M, 10(-10) M, 10(-9) M or 10(-8) M) alone or in combination with Losartan (10(-6) M) in RPMI-1640 replaced the medium for experiments. After the incubation time (0, 1, 2, 6 and 12 h) cells were harvested using 0.05% (w/v) Trypsin and then recovered by centrifugation. The expression of MMP-2, MMP-13, MMP-9 and VEGF in B16F10 cell lysate was assessed by immunoblotting. Angiotensin II significantly enhanced the expression of MMP-2, MMP-13 and VEGF by concentrations as low as 0.1 nM. But angiotensin II could not stimulate any significant increase in MMP-9 expression by angiotensin II in B16F10 cells. Losartan abolished the enhancing effect of every concentration of angiotensin II on MMP-2, MMP-13 and VEGF expression completely and in all incubation times. As a result, angiotensin II through activation of AT1 receptors can stimulate the expression of MMP-2, MMP-13 and VEGF in B16F10 melanoma cells. This is an important conclusion because of the importance of these factors in melanoma invasiveness and the possible important role that angiotensin receptor blockers may play as cancer medications.

Angiotensin-2 receptors (AT1-R and AT2-R), new prognostic factors for renal clear-cell carcinoma?

Background:

The growth factor Angiotensin-2 signals through Angiotensin receptor type 1 (AT1-R) in a broad range of cell types and tumours and through the type-2 receptor (AT2-R) in a more restricted group of cell types. Although numerous forms of cancer have been shown to overexpress AT1-R, expression of AT1-R and AT2-R by human renal clear-cell carcinoma (RCCC) is not well understood. In this study, the expression of both angiotensin receptors was quantified in a retrospective series of RCCC and correlated with prognostic factors.

Methods:

Angiotensin receptor type 1 and AT2-R expressions were quantified on tumour tissues by immunohistochemistry (IHC), western blot and quantitative reverse transcriptase PCR (qRT–PCR). IHC results were correlated to Fuhrman's grade and patient progression-free survival (PFS).

Results:

A total of 84 RCCC were analysed. By IHC, AT1-R and AT2-R were expressed to a greater level in high-grade tumours (AT1-R: P<0.001, AT2-R: P<0.001). Univariate analysis showed a correlation between PFS and AT1-R or AT2-R expression (P=0.001). By multivariate analysis, only AT2-R expression correlated with PFS (HR 1.021, P=0.006) and cancer stage (P<0.001). By western blot, AT1-R and AT1-R were also found to be overexpressed in higher Fuhrman's grade (P<0.01 and P=0.001 respectively). By qRT–PCR, AT1-R but not AT2-R mRNA were downregulated (P=0.001 and P=0.118, respectively).

Conclusion:

Our results show that AT1-R and AT2-R proteins are overexpressed in the most aggressive forms of RCCC and that AT2-R expression correlates with PFS. AT1-R or AT2-R blockage could, therefore, offer novel directions for anti-RCCC therapy.

The renin-angiotensin system and cancer: old dog, new tricks

For cancers to develop, sustain and spread, the appropriation of key homeostatic physiological systems that influence cell growth, migration and death, as well as inflammation and the expansion of vascular networks are required. There is accumulating molecular and in vivo evidence to indicate that the expression and actions of the renin-angiotensin system (RAS) influence malignancy and also predict that RAS inhibitors, which are currently used to treat hypertension and cardiovascular disease, might augment cancer therapies. To appreciate this potential hegemony of the RAS in cancer, an expanded comprehension of the cellular actions of this system is needed, as well as a greater focus on translational and in vivo research.

Flow cytometric analysis of circulating microparticles in plasma

Microparticles, which include exosomes, micro-vesicles, apoptotic bodies and apoptotic microparticles, are small (0.05 - 3 mum in diameter), membranous vesicles that can contain DNA, RNA, miRNA, intracellular proteins and express extracellular surface markers from the parental cells. They can be secreted from intracellular multivesicular bodies or released from the surface of blebbing membranes. Circulating microparticles are abundant in the plasma of normal individuals and can be derived from circulating blood cells such as platelets, red blood cells and leukocytes as well as from tissue sources, such as endothelial and placental tissues. Elevated levels of microparticles are associated with various diseases such as thrombosis (platelet microparticles), congestive heart failure (endothelial microparticles), breast cancer patients (leukocyte microparticles) and women with preeclampsia (syncytiotrophoblast microparticles). Although microparticles can be detected by microscopy, enzyme-linked immunoassays and functional assays, flow cytometry is the preferred method because of the ability to quantitate (fluorescent bead- or flow rate-based method) and because of polychromatic capabilities. However, standardization of pre-analytical and analytical modus operandi for isolating, enumerating and fluorescent labeling of microparticles remains a challenge. The primary focus of this article is to review the preliminary steps required to optimally study circulating in vivo microparticles which include: 1) centrifugation speed used, 2) quantitation of microparticles before antibody labeling, 3) levels of fluorescence intensity of antibody-labeled microparticles, 4) polychromatic flow cytometric analysis of microparticle sub-populations and 5) use of polyclonal antibodies designed for Western blotting for flow cytometry. These studies determine a roadmap to develop microparticles as biomarkers for a variety of conditions.