Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0376358 (prostate cancer)
 59,338 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Features that distinguish tumor vasculatures from normal blood vessels are sought to enable the destruction of preformed tumor vessels. We show that blood vessels in both a xenografted tumor and primary human tumors contain a sizable fraction of immature blood vessels that have not yet recruited periendothelial cells. These immature vessels are selectively obliterated as a consequence of vascular endothelial growth factor (VEGF) withdrawal. In a xenografted glioma, the selective vulnerability of immature vessels to VEGF loss was demonstrated by downregulating VEGF transgene expression using a tetracycline-regulated expression system. In human prostate cancer, the constitutive production of VEGF by the glandular epithelium was suppressed as a consequence of androgen-ablation therapy. VEGF loss led, in turn, to selective apoptosis of endothelial cells in vessels devoid of periendothelial cells. These results suggest that the unique dependence on VEGF of blood vessels lacking periendothelial cells can be exploited to reduce an existing tumor vasculature.
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PMID:Selective ablation of immature blood vessels in established human tumors follows vascular endothelial growth factor withdrawal. 991 26

The efficacy and safety of an immunoconjugate (icon) molecule, composed of a mutated mouse factor VII (mfVII) targeting domain and the Fc effector domain of an IgG1 Ig (mfVII/Fc icon), was tested with a severe combined immunodeficient (SCID) mouse model of human prostatic cancer and an immunocompetent mouse model of mouse prostatic cancer. The SCID mice were first injected s.c. with a human prostatic tumor line, forming a skin tumor that produces a high blood titer of prostate-specific antigen and metastasizes to bone. The icon was encoded in a replication-incompetent adenoviral vector that was injected directly into the skin tumor. The tumor cells infected by the vector synthesize and secrete the icon into the blood, and the blood-borne icon binds with high affinity and specificity to mouse tissue factor expressed on endothelial cells lining the lumen of the tumor vasculature and to human tissue factor expressed on the tumor cells. The Fc domain of the icon activates a cytolytic immune attack against cells that bind the icon. The immunotherapy tests in SCID mice demonstrated that intratumoral injections of the adenoviral vector encoding the mfVII/human Fc icon resulted in long-term regression of the injected human prostatic tumor and also of a distant uninjected tumor, without associated toxicity to the mice. Comparable results were obtained with a SCID mouse model of human melanoma. At the end of the experiments the mice appeared to be free of viable tumor cells. This protocol also could be efficacious for treating cancer patients who have vascularized tumors.
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PMID:Targeting tissue factor on tumor vascular endothelial cells and tumor cells for immunotherapy in mouse models of prostatic cancer. 1159 34

Small cell carcinoma of the prostate (SCCP), although relatively rare, is the most aggressive variant of prostate cancer, currently with no successful treatment. It was therefore tempting to evaluate the response of this violent malignancy and its bone lesions to Pd-Bacteriopheophorbide (TOOKAD)-based photodynamic therapy (PDT), already proven by us to efficiently eradicate other aggressive non-epithelial solid tumors. TOOKAD is a novel bacteriochlorophyll-derived, second-generation photosensitizer recently, developed by us for the treatment of bulky tumors. This photosensitizer is endowed with strong light absorbance (epsilon(0) approximately 10(5) mol(-1) cm(-1)) in the near infrared region (lambda=763nm), allowing deep tissue penetration. The TOOKAD-PDT protocol targets the tumor vasculature leading to inflammation, hypoxia, necrosis and tumor eradication. The sensitizer clears rapidly from the circulation within a few hours and does not accumulate in tissues, which is compatible with the treatment of localized tumor and isolated metastases. Briefly, male CD1-nude mice were grafted with the human SCCP (WISH-PC2) in 3 relevant anatomic locations: subcutaneous (representing tumor mass), intraosseous (representing bone metastases) and orthotopically within the murine prostate microenvironment. The PDT protocol consisted of i.v. administration of TOOKAD (4 mg/kg), followed by immediate illumination (650-800 nm) from a xenon light source or a diode laser emitting at 770 nm. Controls included untreated animals or animals treated with light or TOOKAD alone. Tumor volume, human plasma chromogranin A levels, animal well being and survival were used as end points. In addition, histopathology and immunohistochemistry were used to define the tumor response. Subcutaneous tumors exhibited complete healing within 28-40 days, reaching an overall long-term cure rate of 69%, followed for 90 days after PDT. Intratibial WISH-PC2 lesions responded with complete tumor elimination in 50% of the treated mice at 70-90 days after PDT as documented histologically. The response of the orthotopic model was also analyzed histologically with similar results. The study with this model suggests that TOOKAD-based PDT can reach large tumors and is a feasible, efficient and well-tolerated approach for minimally invasive treatment of local and disseminated SCCP.
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PMID:Photodynamic therapy with Pd-Bacteriopheophorbide (TOOKAD): successful in vivo treatment of human prostatic small cell carcinoma xenografts. 1264 Jun 88

Tumor-associated angiogenesis refers to the growth of new vessels toward and within the tumor. Several studies have revealed that increasing intratumoral microvessel density, a major of tumor-associated angiogenesis, correlates with greater aggressiveness of prostate cancer. Angiogenesis consists of multiple, sequential, and interdependent steps dependent on the local balance of proangiogenic and antiangiogenic molecules Many proangiogenic and antiangiogenic molecules have been demonstrated to regulate growth and metastasis of prostate cancer. As tumor-associated angiogenesis is a crucial step in the process of prostate cancer development, inhibition of tumor neovascularization, and/or destruction of tumor vasculature (antiangiogenic therapy) may maintain the tumors in a dormant state or, perhaps in combination with cytotoxic therapies, potentiate shrinkage of tumors. Recently, therapeutic agents targeting the receptors of proangiogenic molecules and their signal transduction cascade have been developed. In this article, the role of angiogenic molecules in prostate cancer biology, and the application of angiogenesis inhibition to therapeutics for prostate cancer are reviewed.
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PMID:Angiogenesis of prostate cancer and antiangiogenic therapy. 1367 83

The burden of metastatic disease in prostate cancer is largely distributed to bone in the form of osteoblastic metastases. Interactions between malignant epithelial cells of prostate cancer and the bone microenvironment are implicated in the progression of prostate cancer. Because prostate cancer cells in bone metastases express the platelet-derived growth factor receptor (PDGFR), it is possible that inhibition of PDGFR can be an effective means of altering the clinical course of prostate cancer. Preclinical data suggest that preferential expression of PDGFRs in endothelial cells of tumor vasculature in experimental prostate cancer bone metastases is an important target for combination therapy incorporating the PDGFR inhibitor imatinib mesylate. Clinical trials combining imatinib and docetaxel are under way in the metastatic and neoadjuvant settings. Clinical and translational data from these studies are likely to provide additional insights into the role of imatinib in combination therapy for prostate cancer.
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PMID:Combination docetaxel and platelet-derived growth factor receptor inhibition with imatinib mesylate in prostate cancer. 1517 1

In this study, we present a novel approach for the induction of tumor vessel thrombosis using genetically modified coagulation factor X. Human factor X was engineered in its activation peptide in a way that it can be specifically activated by prostate-specific antigen (PSA), a tumor-specific proteinase secreted into the bloodstream by prostate cancer cells. For this purpose we inserted different sequences of known PSA cleavage sites from the natural substrate of PSA, semenogelin I, into the activation peptide of factor X. One FX variant (FX-V4) was further optimized by site-directed mutagenesis of the P2 position and the P5 position (FX-V4-P2YP5R). After preincubation with PSA, FX-V4-P2YP5R was able to efficiently induce coagulation in vitro. These FX variants should be useful for site-specific induction of blood coagulation in the tumor vasculature.
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PMID:Engineering of human coagulation factor x variants activated by prostate-specific antigen. 1566 16

We describe a novel syngeneic "pseudo-orthotopic" in vivo model of prostate cancer progression. Our model uses the dorsal skinfold chamber technique with fluorescence video microscopy and TRAMP-C2 tumor cells. The cells were transfected with a histone H2B-GFP fusion protein, permitting real-time measurement of tumor size, as well as mitotic and apoptotic indices. To generate a "pseudo-orthotopic" milieu, pieces of prostate tissue (10-15 mm2) from donor mice were implanted into the chambers of C57BL/6 mice. The prostate tissue grafted into the chambers retained its native vasculature, as determined by transplantation of prostate tissue from GFP transgenic mice. TRAMP-C2 prostate cancer tumor spheroids (25,000 cells) were implanted in the chamber. Without prostate tissue, TRAMP-C2 prostate tumors were poorly angiogenic, displayed low mitotic and apoptotic indices (0.7 x 10(-4)), and no significant tumor growth could be detected. TRAMP-C2 tumors growing on transplanted prostate tissue in the chamber on the other hand had mitotic indices in the order of 1.6 x 10(-4) and apoptotic indices in the order of 0.8 x 10(-4). Furthermore, tumors with stroma were highly angiogenic, and were fully vascularized within 7-10 days. During a 4-week observation period, the number of tumor cells increased by nearly 300%. We used the model to study the effects of surgical castration. The most profound response was a rapid vascular regression of the tumor vasculature. Castration also increased apoptotic indices within the tumor without significant changes in mitosis. This model may be utilized for the rapid analysis of new therapeutic candidates against prostate cancer.
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PMID:Novel syngeneic pseudo-orthotopic prostate cancer model: vascular, mitotic and apoptotic responses to castration. 1579 54

While 1,25 dihydroxycholecalciferol (calcitriol) is best recognized for its effects on bone and mineral metabolism, epidemiological data indicate that low vitamin D levels may play a role in the genesis and progression of breast, lung, colorectal and prostate cancer, as well as malignant lymphoma and melanoma. Calcitriol has strong antiproliferative effects in prostate, breast, colorectal, head/neck and lung cancer, as well as lymphoma, leukemia and myeloma model systems. Antiproliferative effects are seen in vitro and in vivo. The mechanisms of these effects are associated with G0/G1 arrest, induction of apoptosis, differentiation and modulation of growth factor-mediated signaling in tumor cells. In addition to the direct effects on tumor cells, recent data strongly support the hypothesis that the stromal effects of vitamin D analogs (e.g., direct effects on tumor vasculature) are also important in the antiproliferative effects. Antitumor effects are seen in a wide variety of tumor types and there are few data to suggest that vitamin D-based approaches are more effective in any one tumor type. Glucocorticoids potentiate the antitumor effect of calcitriol and decrease calcitriol-induced hypercalcemia. In addition, calcitriol potentiates the antitumor effects of many cytotoxic agents. Preclinical data indicate that maximal antitumor effects are seen with pharmacological doses of calcitriol and that such exposure can be safely achieved in animals using a high dose, intermittent schedule of administration. AUC and C(max) calcitriol concentrations of 32 ng.h/ml and 9.2 ng/ml are associated with striking antitumor effects in a murine squamous cell carcinoma model and there is increasing evidence from clinical trials that such exposures can be safely attained in patients. Another approach to maximizing intra-tumoral exposure to vitamin D analogs is to inhibit their catabolism. The data clearly indicate that agents which inhibit the major vitamin D catabolizing enzyme, CYP24 (24 hydroxylase), potentiate calcitriol killing of prostate tumor cells in vitro and in vivo. Phase I and II trials of calcitriol, either alone or in combination with carboplatin, taxanes or dexamethasone, as well as the non-specific CYP24 inhibitor, ketoconazole, have been initiated in patients with androgen-dependent and -independent prostate cancer and other advanced cancers. The data indicate that high-dose calcitriol is feasible on an intermittent schedule, no dose-limiting toxicity has been encountered, but the optimal dose and schedule remain to be delineated. Clinical responses have been seen with the combination of high-dose calcitriol + dexamethasone in androgen-independent prostate cancer (AIPC) and, in a large randomized trial in men with AIPC, potentiation of the antitumor effects of docetaxel were seen.
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PMID:Vitamin D compounds: clinical development as cancer therapy and prevention agents. 1688 63

Over the past decade, our program has focused on understanding the role of the physiological environment, tumor vasculature, and metabolism in several of the aggressive phenotypic traits of cancer, such as invasion and metastasis. These studies have been performed primarily with magnetic resonance (MR) imaging (MRI) and spectroscopy (MRS) on human breast and prostate cancer models. During the course of these studies, we observed specific changes in choline phospholipid metabolism associated with a more aggressive phenotype. Molecular or pharmacologic interventions that reduced this aggressiveness were also consistent with a reversal of these alterations. In this contextual review, we have outlined the insight we have gained from these studies and have discussed some of the enzymes and pathways that may present novel targets for pharmaceutical interventions in cancer.
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PMID:Choline phospholipid metabolism in cancer: consequences for molecular pharmaceutical interventions. 1700 48

Expression of the proto-oncogene Bcl-2 is associated with tumor progression. Bcl-2's broad expression in tumors, coupled with its role in resistance to chemotherapy and radiation therapy-induced apoptosis, makes it a rational target for anticancer therapy. Antisense Bcl-2 oligodeoxynucleotide (ODN) reagents have been shown to be effective in reducing Bcl-2 expression in a number of systems. We investigated whether treating human prostate cancer cells with antisense Bcl-2 ODN (G3139, oblimersen sodium, Genasense) before irradiation would render them more susceptible to radiation effects. Two prostate cancer cell lines expressing Bcl-2 at different levels (PC-3-Bcl-2 and PC-3-Neo) were subjected to antisense Bcl-2 ODN, reverse control (CTL), or mock treatment. Antisense Bcl-2 ODN alone produced no cytotoxic effects and was associated with G(1) cell cycle arrest. The combination of antisense Bcl-2 ODN with irradiation sensitized both cell lines to the killing effects of radiation. Both PC-3-Bcl-2 and PC-3-Neo xenografts in mice treated with the combination of antisense Bcl-2 ODN and irradiation were more than three times smaller by volume compared with xenografts in mice treated with reverse CTL alone, antisense Bcl-2 ODN alone, irradiation alone, or reverse CTL plus radiotherapy (P = 0.0001). Specifically, PC-3-Bcl-2 xenograft tumors treated with antisense Bcl-2 ODN and irradiation had increased rates of apoptosis and decreased rates of angiogenesis and proliferation. PC-3-Neo xenograft tumors had decreased proliferation only. This is the first study which shows that therapy directed at Bcl-2 affects tumor vasculature. Together, these findings warrant further study of this novel combination of Bcl-2 reduction and radiation therapy, as well as Bcl-2 reduction and angiogenic therapy.
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PMID:Knock-down of Bcl-2 by antisense oligodeoxynucleotides induces radiosensitization and inhibition of angiogenesis in human PC-3 prostate tumor xenografts. 1723 70


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