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)

Rhenium-188 (beta- = 2.2 MeV; gamma = 155 keV; T1/2 16.9 hours) is an attractive therapeutic radioisotope which is produced from decay of the reactor-produced tungsten-188 parent (T1/2 69 days) and thus conveniently obtained on demand by elution from the alumina-based tungsten-188 /rhenium-188 generator system. The rhenium-188 is obtained as sodium perrhenate by elution of the generator with 0.9% saline. The post elution use of disposable tandem, ion-exchange columns is a simple method for the concentration of rhenium-188 saline solutions with specific volumes > 500 mCi/ml. This method can also extend the useful shelf-life of the generator, which can be as long as one year. The long useful shelf-life of the generator is expected to provide rhenium-188 at very reasonable costs for routine preparation of a variety of radiopharmaceuticals for the treatment of a variety of cancers including breast cancer. We are evaluating two types of Re-188-labeled agents under investigation which have potential for the treatment of breast cancer. Rhenium-188-labeled hydroxyethylidenediphosphonate (HEDP) and Re-188-dimercaptosuccinic acid (DMSA) are being applied for palliative treatment of pain associated with skeletal metastases, and the Re-188-RC-160 somatostatin analogue [cyclic NH2-(D)-Phe-Cys-Try-(D)-Trp-Lys-Val-Cys-Trp-NH2] for somatostatin-receptor-positive tumors. The results of initial clinical studies with the two bone pain agents demonstrate good targeting to skeletal metastases, and use of Re-188-HEDP has resulted in pain palliation with minimal bone marrow suppression in the initial patient studies. While these initial studies have been conducted in patients with prostate cancer, similar results are expected in planned studies in breast cancer patients. In animal studies, Re-188-RC-160 has been successfully used for the local/regional treatment of experimental breast cancer and other cancers. Re-188-RC-160 binds to somatostatin-receptor-positive cells both in vitro and in vivo, including breast cancer cells (ZR-75-1 breast carcinoma and NCI-H69 human small cell ling carcinoma), but not to binding-negative cells (Raji, Burkitt's lymphoma). A structurally similar Re-188-cyclic peptide with different binding specificity (CTOP [cyclic NH2-(D)-Phe-Cys-Try-(D)-Trp-Orn-Thr-Pen-Thr-ol]; an opiate-receptor antagonist) did not bind to target cells. Both gentisic acid and ascorbic acid are present in the Re-188-HEDP and Re-188-RC-160 formulations, and have been found to also significantly reduce radiolytic degradation of the somatostatin peptide analogues, and may have general application in the stabilization of Re-188-labeled radio-pharmaceuticals.
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PMID:Availability of rhenium-188 from the alumina-based tungsten-188/rhenium-188 generator for preparation of rhenium-188-labeled radiopharmaceuticals for cancer treatment. 917 35

To create cytotoxic hybrid analogs of somatostatin (SST), octapeptides RC-160 (D-Phe-Cys-Tyr-D-Trp- Lys-Val-Cys-Trp-NH2) and RC-121 (D-Phe-Cys-Tyr-D-Trp- Lys-Val-Cys-Thr-NH2) were linked to doxorubicin (DOX) or its superactive derivative, 2-pyrrolino-DOX (AN-201). The conjugation was performed by coupling N-9-fluorenylmethoxycarbonyl (N-Fmoc)-DOX-14-O-hemiglutarate or 2-pyrrolino-DOX-14-O-hemiglutarate to the amino terminus of [Lys(Fmoc)5]RC-160 yielding AN-163 and AN-258, respectively, after deprotection. The respective cytotoxic conjugates of RC-121 (AN-162 and AN-238) were prepared similarly. In vitro tests on human cancer cell lines-MKN-45 gastric cancer, MDA-MB-231 breast cancer, PC-3 prostate cancer, and MIA PaCa-2 pancreatic cancer-demonstrated that the antiproliferative activity of the cytotoxic radicals in these conjugates was virtually retained. In H-345 human small cell lung carcinoma cell line, conjugates of RC-121 preserved the cytotoxic activity of their radicals, but the hybrids with RC-160 showed approximately 10 times lower activity. The ability of the carriers and the hybrids to inhibit the binding of 125I-labeled RC-160 to receptors for SST on rat pituitary membrane preparation was also determined. The cytotoxic conjugates inhibited 50% of the specific binding of the radioligand in the nanomolar concentration range (IC50 < 80 nM). When SST-like activities of AN-238 and its carrier, RC-121, were compared in the rat pituitary superfusion system, both compounds were found to suppress a stimulated growth hormone release at nanomolar concentrations. Preliminary studies in animal models of breast and prostate cancers showed that AN-238 is less toxic than AN-201 and more potent in inhibiting tumor growth. These highly active cytotoxic analogs of SST have been designed as targeted antitumor agents for the treatment of various cancers expressing receptors for SST octapeptides.
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PMID:Synthesis and biological evaluation of cytotoxic analogs of somatostatin containing doxorubicin or its intensely potent derivative, 2-pyrrolinodoxorubicin. 946 96

New approaches to target cytotoxic therapy specifically to metastatic prostate cancer sites are urgently needed. As such an approach, an inactive prodrug was synthesized by coupling the primary amine of doxorubicin to the COOH-terminal carboxyl of a seven-amino acid peptide carrier (i.e., Mu-His-Ser-Ser-Lys-Leu-Gln-Leu). The seven-amino acid peptide was documented to be hydrolyzable specifically by the serine protease prostate-specific antigen (PSA) to liberate the active cytotoxin L-leucyl-doxorubicin. Primary cultures of PC-82 human prostate cancer cells secreted high levels of enzymatically active PSA (i.e., 70 +/- 5 ng of enzymatically active PSA/10(6) cells/24 h), whereas LNCaP human prostate cancer cells produced lower levels of enzymatically active PSA (i.e., 2.3 +/- 1 ng/10(6) cells/24 h). LNCaP cells, however, secreted sufficient amounts of enzymatically active PSA to activate the doxorubicin prodrug to a cytotoxic form in vitro. The specificity of the cytotoxic response to the prodrug was demonstrated by the fact that 70 nM of the prodrug killed 50% of the PSA-producing LNCaP cells, whereas doses as high as 1 microM had no cytotoxic effect on PSA-nonproducing TSU human prostate cancer cells in vitro.
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PMID:Enzymatic activation of a doxorubicin-peptide prodrug by prostate-specific antigen. 963 75

Receptors for somatostatin (SST) that are found on prostate cancers might be used for targeting of chemotherapeutic agents. Thus, doxorubicin derivative 2-pyrrolinodoxorubicin (AN-201) can be linked to SST analogue RC-121 (D-Phe-Cys-Tyr-D-Trp-Lys-Val-Cys-Thr-NH2) to form targeted cytotoxic SST analogue AN-238. In this study, we evaluated the effects of AN-238 on the growth of SST receptor (SSTR)-positive androgen-independent Dunning R-3327-AT-1 prostate cancers in Copenhagen rats. The dose range and tumor growth-inhibitory effects of AN-238 and AN-201 were investigated in preliminary experiments. Administration of cytotoxic radical AN-201 at single i.v. doses of 110, 125, and 150 nmol/kg resulted in 0, 77.7, and 100% mortality, respectively, within 6-10 days. Four weeks after the injection of 110 nmol/kg AN-201, mean tumor volume was reduced by 35.1 % (P < 0.05), as compared with controls. In contrast, a single i.v. injection of analogue AN-238 at a dose of 300 nmol/kg was nontoxic and remarkably potent in inhibiting the growth of Dunning AT-1 tumors, resulting in a 85.9% (P < 0.01) reduction in tumor volume after 4 weeks. Treatment with AN-238 extended the survival time of tumor-bearing rats from 52.0+/-3.75 to 91.8+/-3.70 days, corresponding to a 76.5% (P < 0.01) increase. In a comprehensive experiment, we compared the effects of radical AN-201 at 115 nmol/kg, analogue AN-238 at 115 and 300 nmol/kg, carrier SST analogue RC-121 at 300 nmol/kg, and a mixture of AN-201 and RC-121 at doses of 300 nmol/kg administered i.v. Administration of AN-201 at 115 nmol/kg led to 90.0% mortality in 12 days, but animals treated with 115 nmol/kg of AN-238 showed no signs of toxicity, their tumor volume was reduced by 40.0% (P < 0.05), and their tumor weight was reduced by 42.8% (P < 0.01) after 4 weeks, as compared with controls. The dose of 300 nmol/kg of AN-238 was also nontoxic and diminished tumor volume by 80.9% (P < 0.01) and tumor weight by 82.0% (P < 0.01). No reduction in tumor growth or toxic effects was observed with carrier RC-121, but after the injection of unconjugated mixture of AN-201 and RC-121 at doses of 300 nmol/kg, all rats died within 4 days. Specific high-affinity receptors for SST were found on Dunning R-3327-AT-1 tumor membranes by radioligand binding assay and were identified by reverse transcription-PCR as SSTR2. Our study indicates that cytotoxic SST analogue AN-238 can be targeted to SSTRs on tumors and produces a powerful inhibition of the growth of Dunning-AT-1 rat prostate cancer at doses that are nontoxic, whereas its cytotoxic component, 2-pyrrolinodoxorubicin, is toxic and ineffective.
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PMID:Targeted cytotoxic analogue of somatostatin AN-238 inhibits growth of androgen-independent Dunning R-3327-AT-1 prostate cancer in rats at nontoxic doses. 975 25

We evaluated whether AN-238, the cytotoxic analogue of somatostatin (SST) consisting of the radical 2-pyrrolinodoxorubicin (AN-201) linked covalently to the SST octapeptide carrier RC-121 (D-Phe-Cys-Tyr-D-Trp-Lys-Val-Cys-Thr-NH2), could be used for targeting human primary and metastatic prostate carcinomas that express SST receptors (SSTRs). The antitumor activity and toxicity of AN-238 and its components were first characterized in nude mice bearing s.c. xenografts of PC-3 human androgen-independent prostate cancer. In experiment 1, AN-238 was injected once i.v. at 200 nmol/kg when the mean volume of s.c. tumors was about 30 mm3. Administration of AN-238 inhibited tumor growth, as shown by a 74% decrease in tumor volume and by a 71% reduction in tumor weight after 7 weeks as compared with the control group. AN-201 at an equimolar dose did not show any antitumor activity. The mortality was 14.3% (one of seven mice) in the AN-238-treated group and 47% (three of seven mice) in mice that received AN-201. In experiment 2, two i.v. injections of AN-238 at 150 nmol/kg were given 10 days apart when the tumors measured 65-70 mm3. A significant inhibition of tumor volume (62.3%; P < 0.001) and tumor weight (61.1%; P < 0.01) was observed after 4 weeks of treatment. AN-201, given alone at the same dose or coadministered with RC-121, had no significant effect on PC-3 tumors. The suppression of tumor growth induced by AN-238 was accompanied by a significant enhancement of apoptosis (P < 0.01). There were similar side effects in all treated groups, which included a transient loss of body weight and leukopenia. The effectiveness of AN-238 in a metastatic model was then investigated in animals implanted orthotopically with 2 x 10(6) PC-3 cells. Two i.v. injections of AN-238 or AN-201 at 150 nmol/kg were administered 10 days apart at 10 weeks after intraprostatic inoculation of PC-3 cells. After 4 weeks of treatment, the mean weight of primary tumors in animals receiving AN-238 was 77% lower (P < 0.01) than that in controls. This reduction was also significantly greater (P < 0.05) than that in animals given AN-201, which showed only a 34% inhibition (nonsignificant versus controls). All control animals and four of six (67%) mice treated with AN-201 developed metastases in the lymph nodes; however, no lymphatic spread of cancer was found in the AN-238-treated group. Using reverse transcription-PCR analysis, we demonstrated the expression of SSTR2 and SSTR5 in intraprostatic tumors and their metastases in lymph nodes as well as in s.c. tumors. The present study demonstrates the high efficacy of SSTR-targeted chemotherapy in a model of advanced human androgen-independent prostatic carcinoma, as shown by the inhibition of primary tumors and their metastases by the cytotoxic SST analogue AN-238.
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PMID:Inhibition of PC-3 human androgen-independent prostate cancer and its metastases by cytotoxic somatostatin analogue AN-238. 1021 5

In view of non-specific toxicity of most chemotherapeutic agents against normal cells, the development of targeted chemotherapy is warranted. Efficient targeting of chemotherapeutic drugs to the cancerous area could be of great benefit for patients with advanced or metastatic tumors. Targeted cytotoxic peptide conjugates are hybrid molecules composed of a peptide carrier which binds to receptors on tumors and a cytotoxic moiety. New cytotoxic analogs of LHRH, AN-152 in which doxorubicin (DOX) is linked to [d-Lys(6)]LHRH, and AN-207 which consists of 2-pyrrolino-DOX (AN-201) coupled to the same carrier, show high-affinity binding and are much less toxic and more effective in vivo than their respective radicals in inhibiting tumor growth in LHRH receptor-positive models of human ovarian, mammary, or prostatic cancer. These results suggest that targeted cytotoxic LHRH analogs such as AN-207 could be considered for treatment of these cancers. The presence of receptors for bombesin-like peptides on a wide variety of tumors prompted us to use some of our bombesin/gastrin-releasing peptide antagonists as carrier molecules. Cytotoxic bombesin analogs, such as AN-215 containing AN-201, might find application in the treatment of small cell lung carcinoma (SCLC), and colorectal, gastric, pancreatic, mammary, and prostatic cancers. Since somatostatin receptors are found in various human neoplasms and the receptor subtypes to which octapeptide analogs bind with high affinity have been identified, we synthesized several cytotoxic somatostatin analogs including AN-162 and AN-238 containing DOX and 2-pyrrolino-DOX respectively, linked to octapeptide RC-121. Cytotoxic somatostatin analog AN-238 efficaciously inhibits growth of human breast or prostate cancers expressing somatostatin receptors-2 and -5 and can be used for receptor-targeted chemotherapy. Cytotoxic somatostatin analogs might also find applications for the therapy of human pancreatic, colorectal, and gastric cancer as well as brain tumors and non-SCLC. Cytotoxic compounds linked to analogs of hormonal peptides like LHRH, bombesin, and somatostatin that can be targeted to certain tumors possessing receptors for those peptides could be an important addition to oncological armamentarium.
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PMID:Cancer chemotherapy based on targeting of cytotoxic peptide conjugates to their receptors on tumors. 1040 15

Polymeric drug conjugates are used in cancer therapy and, varying their molecular size and charge, will affect their in vivo transport and extravasation in tumours. Partitioning between tumour vasculature and tumour tissue will be of particular significance in the case of photosensitizer conjugates used in photodynamic therapy, where this partitioning can lead to different therapeutic effects. Poly-l-lysine chlorin e6conjugates (derived from polymers of average Mr 5000 and 25000) were prepared both in a cationic state and by poly-succinylation in an anionic state. A fluorescence scanning laser microscope was used to follow the pharmacokinetics of these conjugates in vivo in an orthotopic rat prostate cancer model obtained with MatLyLu cells. Fluorescence was excited with the 454-528 nm group of lines of an argon laser and a 570 nm long pass filter used to isolate the emission. Results showed that the conjugates initially bound to the walls of the vasculature, before extravasating into the tissue, and eventually increasing in fluorescence. The anionic conjugates produced tissue fluorescence faster than the cationic ones, and surprisingly, the larger Mr conjugates produced tissue fluorescence faster than the smaller ones with the same charge. These results are consistent with differences in aggregation state between conjugates.
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PMID:In vivo fluorescence imaging of the transport of charged chlorin e6 conjugates in a rat orthotopic prostate tumour. 1049 51

Angiostatin, a potent inhibitor of angiogenesis, tumour growth and metastasis, is a biologically active fragment of plasminogen, containing the kringle domains 1-4. It is generated from plasminogen by limited proteolysis. We show that prostate-specific antigen (PSA), a serine proteinase secreted by human prostate and human prostate cancer cells, is able to convert Lys-plasminogen to biologically active angiostatin-like fragments, containing kringles 1-4, by limited proteolysis of peptide bond Glu439-Ala440 in vitro. In an in vitro morphogenesis assay, the purified angiostatin-like fragments inhibited proliferation and tubular formation of human umbilical vein endothelial cells with the same efficacy as angiostatin. This finding might help to understand growth characteristics of prostate cancer, which usually has low microvessel density and slow proliferation.
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PMID:Generation of angiostatin-like fragments from plasminogen by prostate-specific antigen. 1060 21

Some of the most promising systems for the controlled release of bioactive agents, i.e., peptides or hormones, involve the encapsulation or entrapment of hormones or peptides in biocompatible polymeric devices that enable their continuous release over prolonged periods. In urology, two major pathologic conditions, androgen deficiency and prostate cancer, currently benefit from treatments based on controlled delivery. Leuprolide acetate depot (Lupron-depot) was one of the first controlled-delivery systems used for the treatment of prostate cancer. Clinical studies indicate that patients with prostate cancer who undergo therapy with leuprolide acetate depot can benefit from this treatment. Currently available androgen-replacement therapies include the oral administration of testosterone tablets or capsules, depot injections, sublingual treatment, and skin patches. However, side effects such as metabolic inactivation of testosterone on oral administration; fluctuations in levels of the hormone; and burning, rash, and skin necrosis during the use of skin patches may occur. These side effects may be avoided through the application of encapsulated Leydig cells, which produce testosterone. Studies in our laboratory have shown that Leydig cells encapsulated in alginate/poly-L-lysine/alginate microspheres are capable of secreting testosterone in culture and in vivo. Microencapsulated Leydig cells delivered intraperitoneally into castrated rats maintained a testosterone level of 0.51 ng/ml for more than 3 months without any human chorionic gonadotropin stimulation. Similar studies are also being conducted in our laboratory on encapsulation of ovarian cells for the secretion of progesterone and estrogen in culture and in vivo using microencapsulation techniques.
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PMID:Controlled release of therapeutic agents: slow delivery and cell encapsulation. 1076 49

The androgen receptor (AR) is a sequence-specific DNA-binding protein that plays a key role in prostate cancer cellular proliferation by dihydrotestosterone and the induction of secondary sexual characteristics. In this study we demonstrate that the AR can be modified by acetylation in vitro and in vivo. p300 and p300/cAMP-response element-binding protein acetylated the AR at a highly conserved lysine-rich motif carboxyl-terminal to the zinc finger DNA-binding domain. [(14)C]acetate-labeling experiments demonstrated that AR acetylation by p300 in cultured cells requires the same residues identified in vitro. Point mutation of the AR acetylation site (K632A/K633A) abrogated dihydrotestosterone-dependent transactivation of the AR in cultured cells. Mutation of the p300 CH3 region or the p300/cAMP-response element-binding protein histone acetylase domain reduced ligand-dependent AR function. The identification of the AR as a direct target of histone acetyltransferase co-activators has important implications for targeting inhibitors of AR function.
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PMID:p300 and p300/cAMP-response element-binding protein-associated factor acetylate the androgen receptor at sites governing hormone-dependent transactivation. 1077 4


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