Angiogenesis-targeted therapies in prostate cancer

Comparison of metastatic castration-resistant prostate cancer in bone with other sites: clinical characteristics, molecular features and immune status

Metastatic castration-resistant prostate cancer (mCRPC) is the lethal stage and the leading cause of death in prostate cancer patients, among which bone metastasis is the most common site. Here in this article, we downloaded the gene expression data and clinical information from online dataset. We found that prostate cancer metastasis in bone is prone to have higher prostate-specific antigen (PSA) and longer time on first-line androgen receptor signaling inhibitors (ARSI). A total of 1,263 differentially expressed genes (DEGs) were identified and results of functional enrichment analysis indicated the enrichment in categories related to cell migration, cancer related pathways and metabolism. We identified the top 20 hub genes from the PPI network and analyzed the clinical characteristics correlated with these hub genes. Finally, we analyzed the immune cell abundance ratio of each sample in different groups. Our results reveal the different clinical characteristics, the immune cell infiltration pattern in different sites of mCRPC, and identify multiple critical related genes and pathways, which provides basis for individualized treatment.

Association between five polymorphisms in vascular endothelial growth factor gene and urinary bladder cancer risk: A systematic review and meta-analysis involving 6671 subjects

BACKGROUND

Vascular endothelial growth factor (VEGF) gene plays a key role in angiogenesis and tumor growth. The relationship between VEGF gene polymorphisms and bladder cancer (BCa) risk was studied extensively in recent years. However, the currently available results are controversial. To ascertain whether VEGF polymorphisms are associated with the susceptibility to BCa, we conducted this systematic review and meta-analysis.

MATERIALS AND METHODS

Relevant studies were collected systemically from PubMed, Medline, Embase, Web of Science databases and the Cochrane Library. Odds ratios (ORs) and 95% confidence intervals (CIs) were evaluated using random or fixed effects models by Stata statistical software. This systematic review protocol was registered at International prospective register of systematic reviews (PROSPERO) under number CRD42018099279.

RESULTS

A total of eight articles including twenty case-control studies with 3206 BCa cases and 3645 controls were enrolled for this meta-analysis. By pooling all eligible studies, we found that rs3025039, rs833052 and rs25648 polymorphisms were significantly associated with BCa risk. However, in subgroup analyses by stage, we identified a decreased association between the rs699947 A-allele and Muscle-invasive Bladder Cancer (MIBC) under allele contrast, homozygous and recessive genetic models (A vs C: OR = 0.76; AA vs CC: OR = 0.49, 95%CI = 0.27-0.90, I² = 0.0%, P = 0.021; AA vs CA + CC: OR = 0.60, 95%CI = 0.38-0.96, I² = 0.0%, P = 0.034). As to ethnicity subgroup analysis, rs699947 and rs3025039 polymorphisms were thought as a risk factor for BCa risk in Asian population, while a decreased association was revealed between rs699947 (C > A) A-allele and BCa risk in African population under dominant, recessive, homozygous, heterozygous and allele contrast genetic models. While for other polymorphisms, null results were found.

CONCLUSION

Our meta-analysis suggested that rs3025039 (C > T), rs833052 (C > A) and rs25648 (C > T) polymorphisms of VEGF gene increased susceptibility to BCa risk. And our study also demonstrated homozygous TT genotype in rs3025039, homozygous AA genotype in rs833052 and homozygous TT genotype in rs25648 were significantly relevant to elevated BCa risk. In the meanwhile, it is worth noting that rs699947 (C > A) A-allele should be thought as a protective factor for MIBC.

Association between vascular endothelial growth factor rs699947 polymorphism and the risk of three major urologic neoplasms (bladder cancer, prostate cancer, and renal cell carcinoma): A meta-analysis involving 11,204 subjects

BACKGROUND

The relationship between vascular endothelial growth factor (VEGF) gene variant rs699947 polymorphism and urologic neoplasms risk was studied extensively in recent years. The VEGF gene plays a key role in angiogenesis of urologic neoplasms, but some conclusions are still inconclusive. The aim of this study was to determine whether this polymorphism is a risk factor for susceptibility to urologic neoplasms by conducting a meta-analysis.

METHODS

We performed a meta-analysis of 15 different publications from the PubMed, Embase and Medline databases, to better assess the association between VEGF rs699947 polymorphism and urologic neoplasms risk. Odds ratios (ORs) and 95% confidence intervals (CIs) were evaluated using random or fixed effects models.

RESULTS

By pooling all eligible studies, we found that the VEGF rs699947 polymorphism was not associated with overall urologic neoplasms. However, subgroup analysis based on cancer types demonstrated that significantly increased association was found between VEGF rs699947 polymorphism and the risk of bladder cancer (BCa) under heterozygous genetic model (OR = 1.48, 95%CI = 1.17-1.89). And rs699947 polymorphism was also identified an increased risk of renal cell carcinoma (RCC) under dominant, recessive, homozygous, heterozygous and allelic contrast genetic models, while no association was observed in prostate cancer (PCa). In addition, in subgroup analysis by ethnicity, we found rs699947 polymorphism was associated with Asian population under dominant, homozygous, heterozygous and allelic contrast genetic models. No evidence of publication bias was found (Begg's test, P = 0.855; Egger's test, P = 0.590).

CONCLUSIONS

In summary, our study showed evidence that the VEGF rs699947 polymorphism was obviously associated with an increased risk of bladder cancer and renal cell carcinoma, particularly in Asian population, while no significant association was observed in overall urologic neoplasms. Future studies with larger sample sizes are warranted to further evaluate these associations in more details.

The Culinary-Medicinal Mushroom Coprinus comatus as a Natural Antiandrogenic Modulator

Prostate cancer is the most common cancer diagnosed in men. Chemotherapy, androgen ablation, and androgen antagonist treatments have proven to have significant effects in the early stages of prostate cancer, whereas advanced prostate cancer is resilient to such treatments. The androgen receptor (AR), a ligand-dependent transcription factor, is the major drug target of prostate cancer therapy. Transition to the androgen-independent stage involves the activation of signaling pathways, AR gene mutations, and other mechanisms. Higher basidiomycetes mushrooms have been used since ancient times in folk medicine to treat a diversity of diseases, including cancer. The present study evaluates the antiandrogenic activity of different Coprinus comatus strains in their ability to interfere with AR function. The authors found that the most active extract was C comatus strain 734 extracted with hexane (CC734-H). This extract was able to (1) inhibit AR-mediated reporter activity, (2) inhibit the proliferation and viability of the LNCaP cell line, and (3) inhibit the colony formation of the LNCaP cell line, in comparison to the DU-145, PC-3, and MDA-Kb2 cells. In addition, CC734-H was able to reduce AR levels and prostate-specific antigen gene expression in the LNCaP-treated cell line. This study illustrates the potential of the C comatus mushroom as a natural antiandrogenic modulator that could serve in the treatment of prostatic diseases.

Angiogenesis as a strategic target for prostate cancer therapy

It is becoming increasingly clear that angiogenesis plays a crucial role in prostate cancer (CaP) survival, progression, and metastasis. Tumor angiogenesis is a hallmark of advanced cancers and an attractive treatment target in multiple solid tumors. By understanding the molecular basis of resistance to androgen withdrawal and chemotherapy in CaP, the rational design of targeted therapeutics is possible. This review summarizes the recent advancements that have improved our understanding of the role of angiogenesis in CaP metastasis and the potential therapeutic efficacy of inhibiting angiogenesis in this disease. Current therapeutic options for patients with metastatic hormone-refractory CaP are very limited. Targeting vasculature is a developing area, which shows promise for the control of late stage and recurrent CaP disease and for overcoming drug resistance. We discuss angiogenesis and its postulated mechanisms and focus on the regulation of angiogenesis in CaP progression and the therapeutic beneficial effects associated with targeting of the CaP vasculature to overcome the resistance to current treatments and CaP recurrence.

Anticancer and cancer chemopreventive potential of grape seed extract and other grape-based products

With emerging trends in the incidence of cancer of various organ sites, additional approaches are needed to control human malignancies. Intervention or prevention of cancer by dietary constituents, a strategy defined as chemoprevention, holds great promise in our conquest to control cancer, because it can be implemented on a broader population base with less economic burden. Consistent with this, several epidemiological studies have shown that populations that consume diets rich in fruits and vegetables have an overall lower cancer incidence. Based on these encouraging observations, research efforts from across the globe have focused on identifying, characterizing, and providing scientific basis to the efficacy of various phytonutrients in an effort to develop effective strategy to control various human malignancies. Cancer induction, growth, and progression are multi-step events and numerous studies have demonstrated that various dietary agents interfere with these stages of cancer, thus blocking malignancy. Fruits and vegetables represent untapped reservoir of various nutritive and nonnutritive phytochemicals with potential cancer chemopreventive activity. Grapes and grape-based products are one such class of dietary products that have shown cancer chemopreventive potential and are also known to improve overall human health. This review focuses on recent advancements in cancer chemopreventive and anticancer efficacy of grape seed extract and other grape-based products. Overall, completed studies from various scientific groups conclude that both grapes and grape-based products are excellent sources of various anticancer agents and their regular consumption should thus be beneficial to the general population.

Grundlagen der systemischen Therapie

Die Einführung sog. »zielgerichteter Medikamente« hat einen Paradigmenwechsel in der Systemtherapic maligner Erkrankungen ausgelöst. Voraussetzung hierfür waren die in den letzten 25 Jahren gesammelten Erkenntnisse der molekularbiologischen, molekulargenetischen und immunologischen Grundlagenforschung, die ein besseres Verständnis der pathogenetischen Prozesse im Rahmen der malignen Transformation und Tumorprogression sowie die Identifikation strategischer Zielstrukturen (»Targets«) ermöglichen. Auf diese Weise wurde ein neuer Ansatz der Entwicklung antineoplastischer Therapeutika angestoßen, der auf die Wirkung an spezifischen Molekülaktivitäten und nicht primär auf zelluläre Endpunkte (Wachstumshemmung, Zelltod) ausgerichtet ist.

Thymoquinone inhibits tumor angiogenesis and tumor growth through suppressing AKT and extracellular signal-regulated kinase signaling pathways

Thymoquinone, a component derived from the medial plant Nigella sativa, has been used for medical purposes for more than 2,000 years. Recent studies reported that thymoquinone exhibited inhibitory effects on cell proliferation of many cancer cell lines and hormone-refractory prostate cancer by suppressing androgen receptor and E2F-1. Whether thymoquinone inhibits tumor angiogenesis, the critical step of tumor growth and metastasis, is still unknown. In this study, we found that thymoquinone effectively inhibited human umbilical vein endothelial cell migration, invasion, and tube formation. Thymoquinone inhibited cell proliferation and suppressed the activation of AKT and extracellular signal-regulated kinase. Thymoquinone blocked angiogenesis in vitro and in vivo, prevented tumor angiogenesis in a xenograft human prostate cancer (PC3) model in mouse, and inhibited human prostate tumor growth at low dosage with almost no chemotoxic side effects. Furthermore, we observed that endothelial cells were more sensitive to thymoquinone-induced cell apoptosis, cell proliferation, and migration inhibition compared with PC3 cancer cells. Thymoquinone inhibited vascular endothelial growth factor-induced extracellular signal-regulated kinase activation but showed no inhibitory effects on vascular endothelial growth factor receptor 2 activation. Overall, our results indicate that thymoquinone inhibits tumor angiogenesis and tumor growth and could be used as a potential drug candidate for cancer therapy.

Targeting vasculature in urologic tumors: mechanistic and therapeutic significance

Recent advances toward understanding the molecular mechanisms regulating cancer initiation and progression provide new insights into the therapeutic value of targeting tumor vascularity by interfering with angiogenic signaling pathways. The functional contribution of key angiogenic factors toward increased vascularity characterizing metastatic tumors and their therapeutic exploitation is considered in three major urologic malignancies, renal, bladder, and prostate cancer. With the realization that the success of the therapeutic efficacy of the various anti-angiogenic approaches for the treatment of urologic tumors has yet to be proven clinically, the challenge remains to select critical angiogenesis pathways that can be targeted for an individual tumor. Here we discuss the major mechanisms that support formation of vasculature in renal, bladder, and prostate tumors and the current results of targeting of specific molecules/regulators for therapeutic intervention against metastastic disease.

The aryl hydrocarbon receptor (AhR) inhibits vanadate-induced vascular endothelial growth factor (VEGF) production in TRAMP prostates

Hypoxia-inducible factor-1 alpha (HIF-1alpha) and aryl hydrocarbon receptor nuclear translocator (ARNT) are basic helix-loop-helix/per-arnt-sim (PAS) family transcription factors. During angiogenesis and tumor growth, HIF-1alpha dimerizes with ARNT, inducing expression of many genes, including vascular endothelial growth factor (VEGF). ARNT also dimerizes with the aryl hydrocarbon receptor (AhR). AhR-null (Ahr(-/-)) transgenic adenocarcinoma of the mouse prostate (TRAMP) mice develop prostate tumors with greater frequency than AhR wild-type (Ahr(+/+)) TRAMP mice, even though prevalence of prostate epithelial hyperplasia is not inhibited. This suggests that Ahr inhibits prostate carcinogenesis. In TRAMP mice, prostatic epithelial hyperplasia results in stabilized HIF-1alpha, inducing expression of VEGF, a prerequisite for tumor growth and angiogenesis. Since ARNT is a common dimerization partner of AhR and HIF-1alpha, we hypothesized that the AhR inhibits prostate tumor formation by competing with HIF-1alpha for ARNT, thereby limiting VEGF production. Prostates from Ahr(+/+), Ahr(+/-) and Ahr(-/-) C57BL/6J TRAMP mice were cultured in the presence of graded concentrations of vanadate, an inducer of VEGF through the HIF-1alpha-ARNT pathway. Vanadate induced VEGF protein in a dose-dependent fashion in Ahr(+/-) and Ahr(-/-) TRAMP cultures, but not in Ahr(+/+) cultures. However, vanadate induced upstream proteins in the phosphatidylinositol 3-kinase-signaling cascade to a similar extent in TRAMPs of each Ahr genotype, evidenced by v-akt murine thymoma viral oncogene homolog (Akt) phosphorylation. These findings suggest that AhR sequesters ARNT, decreasing interaction with HIF-1alpha reducing VEGF production. Since VEGF is required for tumor vascularization and growth, these studies further suggest that reduction in VEGF correlates with inhibited prostate carcinogenesis in Ahr(+/+) TRAMP mice.

Prognostic value of p16 in locally advanced prostate cancer: a study based on Radiation Therapy Oncology Group Protocol 9202

PURPOSE

Deregulation of the retinoblastoma (RB) pathway is commonly found in virtually all known human tumors. p16, the upstream regulator of RB, is among the most commonly affected member of this pathway. In the present study, we examined the prognostic value of p16 expression in men with locally advanced prostate cancer who were enrolled on Radiation Therapy Oncology Group protocol 9202.

PATIENTS AND METHODS

RTOG 9202 was a phase III randomized study comparing long-term (LT) versus short-term (ST) androgen-deprivation therapy (AD). Of the 1,514 eligible cases, 612 patients had adequate tumor material for p16 analysis. Expression levels of p16 were determined by immunohistochemistry (IHC). IHC staining was scored quantitatively using an image analysis system.

RESULTS

On multivariate analysis, intact p16 expression was significantly associated with decreased rate of distant metastases (P = .0332) when both STAD and LTAD treatment arms were considered together. For patients with intact (high levels of immunostaining) p16 (mean p16 index > 81.3%), LTAD plus radiotherapy (RT) significantly improved prostate cancer survival (PCS) compared with STAD plus RT (P = .0008) and reduced the frequency of distant metastasis (P = .0069) compared with STAD plus RT. In contrast, for patients with tumors demonstrating p16 loss (low levels of immunostaining, mean p16 index < or = 81.3%), LTAD plus RT significantly improved biochemical no evidence of disease survival over STAD (P < .0001) primarily by decreasing the frequency of local progression (P = .02), as opposed to distant metastasis, which was the case in the high-p16 cohort.

CONCLUSION

Low levels of p16 on image analysis appear to be associated with a significantly higher risk of distant metastases among all study patients. p16 expression levels also appear to identify patients with locally advanced prostate cancer with distinct patterns of failure after LTAD.

IRL-1620, a tumor selective vasodilator, augments the uptake and efficacy of chemotherapeutic agents in prostate tumor rats

BACKGROUND

IRL-1620, a potent endothelin B receptor agonist, enhanced the efficacy of paclitaxel in a breast tumor model, but its effect in prostate cancer is not known. The present study was conducted to evaluate the effect of IRL-1620 on tumor perfusion, uptake of [(14)C]-doxorubicin in the tumor and efficacy of doxorubicin (DOX), and 5-flurouracil (5-FU) in a rat prostate tumor model.

METHODS

JHU-4 (Mat-Lu) cells inoculated prostate tumor model in Copenhagen rats was used for the study.

RESULTS

Administration of IRL-1620 (3 nmol/kg, i.v) significantly increased (102.8%) prostate tumor perfusion and tumor uptake of [(14)C]-doxorubicin (115%) compared to vehicle treated rats. Results of the efficacy study demonstrate that IRL-1620 administration 15 min prior to DOX (5 mg/kg) or 5-FU (50 mg/kg) on every third day for a total of four doses significantly reduced tumor volume compared to vehicle treated rats.

CONCLUSIONS

IRL-1620 significantly enhanced the uptake and efficacy of anticancer agents in prostate cancer.

Establishment and characterization of androgen-independent human prostate cancer cell lines, LN-REC4 and LNCaP-SF, from LNCaP

AIM

To investigate the mechanisms of androgen-independent growth in prostate cancer (PCa), we established two PCa cell lines, LN-REC4 and LNCaP-SF, from the androgen-dependent PCa cell line, LNCaP.

MATERIALS AND METHODS

LN-Pre and LN-REC4 cells were generated from LNCaP tumors grown on intact and castrated severe combined immunodeficient (SCID) mouse, respectively. After we cultured LNCaP cells under a steroid-free conditions for 6 months in vitro, LNCaP-SF cells were established. To show the character of LN-REC4 and LNCaP-SF cells, androgen sensitivity was investigated through examination of growth rate, and prostate-specific antigen (PSA), androgen receptor (AR), p21, p27, and cyclin D1 expression were examined by reverse transcription-polymerase chain reaction (RT-PCR). Angiogenesis assay in vitro was carried out using conditioned medium. To examine the expression level of vascular endothelial growth factor (VEGF), RT-PCR and enzyme-linked immunosorbent assay were also done.

RESULTS AND CONCLUSIONS

LN-REC4 cells proliferated better than LNCaP cells in castrated mice and did well irrespective of castration, although responsiveness for androgen of LN-REC4 cells attenuated less than that of LNCaP cells in vitro. LNCaP-SF cells in castrated mice proliferated more rapidly than in normal mice. The PSA expression in LNCaP-SF cells was still induced by androgen. Expression of AR, p21, p27 and cyclin D1 were not changed in LN-REC4 and LNCaP-SF cells. Angiogenesis assay showed that both cells stimulated angiogenesis. LN-REC4 induced VEGF more than LNCaP and LN-Pre cells. However, expression of VEGF per cell in LNCaP-SF was lower than LNCaP cells, suggesting that other factors might be involved in angiogenesis. These cell lines might be a useful tool for researching androgen-independent growth and treatments of recurred PCa.

Biologic agents as adjunctive therapy for prostate cancer: a rationale for use with androgen deprivation

The prevalence of prostate cancer emphasizes the need for improved therapeutic options, particularly for metastatic disease. Current treatment includes medical or surgical castration, which initially induces apoptosis of prostate cancer cells, but ultimately an androgen-independent subpopulation emerges. In addition to a transient therapeutic effect, androgen-deprivation therapy (ADT) can initiate biochemical events that may contribute to the development of and progression to an androgen-independent state. This transition involves multiple signal transduction pathways that are accompanied by many biochemical changes resulting from ADT. These molecular events themselves are therapeutic targets and serve as a rationale for adjunctive treatment at the time of ADT.

Mechanisms Regulating Tumor Angiogenesis by 12-Lipoxygenase in Prostate Cancer Cells

12-Lipoxygenase utilizes arachidonic acid to synthesize 12(S)-hydroperoxyeicosatetraenoic acid, which is converted to the end product 12(S)-hydroxyeicosatetraenoic acid, an eicosanoid that promotes tumorigenesis and metastasis. Increased expression of 12-lipoxygenase has been documented in a number of carcinomas. When overexpressed in human prostate or breast cancer, 12-lipoxygenase promotes tumor angiogenesis and growth in vivo. The present study was undertaken to delineate the mechanisms by which 12-lipoxygenase enhances angiogenesis. Herein we report that nordihydroguaiaretic acid, a pan inhibitor of lipoxygenases and baicalein, a selective inhibitor of 12-lipoxygenase, reduced VEGF expression in human prostate cancer PC-3 cells. Overexpression of 12-lipoxygenase in PC-3 cells resulted in a 3-fold increase in VEGF protein level when compared with vector control cells. An increase in PI 3-kinase activity was found in 12-LOX-transfected PC-3 cells and inhibition of PI 3-kinase by LY294002 significantly reduced VEGF expression. Northern blot and real time PCR analyses revealed an elevated VEGF transcript level in PC-3 cells transfected with a 12-lipoxygenase expression construct. Using a VEGF promoter luciferase construct (-1176/+54), we found a 10-fold increase in VEGF promoter activity in 12-lipoxygenase-transfected PC-3 cells. The region located between -88 and -66 of the VEGF promoter was identified as 12-lipoxygenase responsive using VEGF promoter-based luciferase assays. Further analysis with mutant constructs indicated Sp1 as a transcription factor required for 12-lipoxygenase stimulation of VEGF. Neutralization of VEGF by a function-blocking antibody significantly decreased the ability of 12-lipoxygenase-transfected PC-3 cells to stimulate endothelial cell migration, suggesting VEGF as an important effector for 12-lipoxygenase-mediated stimulation of tumor angiogenesis.

Current status and perspective of antiangiogenic therapy for cancer: urinary cancer

Angiogenesis is considered a prerequisite for solid tumor growth. Antiangiogenic therapy reduces tumor size and extends host survival in a number of preclinical animal models. However, in humans antiangiogenic therapy is a poor promoter of tumor regression and has shown minimal effect on patient survival. In urinary cancers, such as renal cell cancer, prostate cancer, and bladder cancer, advanced refractory disease is a good candidate for antiangiogenic therapy because of its resistance to ordinary chemotherapy, radiotherapy, and hormonal therapy. Unique characteristics of molecular mechanisms underlie the induction of angiogenesis in urinary cancers. In this review, we summarize these unique mechanisms and review the results of clinical trials of antiangiogenic therapy for these cancers, discussing prospects and problems relating to antiangiogenic therapy.

Growth factor signalling in prostatic growth: significance in tumour development and therapeutic targeting

The intricate balance maintained between cell growth and proliferation factors and apoptosis-inducing factors is fundamental to the regulation of prostate growth. Disruptions in this homeostasis often trigger the loss of apoptosis and the over-expression of factors promoting cell survival and proliferation, inevitably leading to tumorigenesis and cancer. Deregulation of prostate growth during prostate cancer development and progression is characterized by apoptotic evasion, uncontrolled proliferation, and increased invasive potential. Thus, in advanced stages of disease progression, surviving prostate tumour cells acquire the ability to migrate and invade heterotopic tissues, with the bone and lymph nodes being the most common sites for human prostate cancer metastasis. The challenges in the implementation of effective therapeutic strategies for the treatment of advanced metastatic prostate cancer reflect the multidimensional nature and functional significance of antiapoptotic pathways in the emergence of therapeutic resistance of prostate tumours. In this chapter, we discuss the current understanding of the molecular mechanisms governing growth factor signalling pathways with often overlapping functions that contribute to loss of apoptosis control and activation of cell proliferation towards aggressive prostate tumorigenic growth and metastatic behaviour. While a full understanding of the prosurvival characteristics of these growth factor pathways is still evolving, the impact that growth factors such a epidermal growth factor and transforming growth factor-beta can be recognized by the vigorous attempts at therapeutic targeting of their key signalling steps.