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)

Androgen ablation-induced prostate cancer regression is transient and ends with the regrowth of androgen-independent (AI) tumors. To mimic this evolution in culture, we chronically deprived an androgen-dependent (AD) prostate cancer cell line (LNCaP) of androgen, generating an AI derivative which retained limited hormone proliferative responsiveness and a barely detectable prostate-specific antigen (PSA) mRNA level. While the cytokeratin 8 (CK8) level was low, the androgen receptor (AR) protein in AI cells was on average tenfold greater than in AD cells. When challenged for susceptibility to undergo apoptosis, the AI cells were more resistant than AD cells to all-trans retinoic acid (tRA) and two chemotherapeutic agents, Taxol and Adriamycin, requiring higher doses and longer periods of treatment to achieve similar effects. Compared to AD cells, the partially apoptosis-resistant AI cells expressed four times more Bcl-2 protein and undetectable levels of p21/WAF1. Induction of apoptosis by tRA in both cell types did not affect their expression but was preceded by the activation of Rb and a pronounced reduction of AR protein level. The kinetics of the Rb activation and AR downmodulation in both cell types matched their tRA sensitivity, suggesting that these events may be required for tRA-induced apoptosis. The results show that the apoptotic pathway in AI cells, although more difficult to induce, is not irrevocably lost and that targeted reduction of the AR protein level with retinoids in combination with androgen ablation therapy may prolong remissions in advanced prostate cancer patients.
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PMID:Activation of Rb and decline in androgen receptor protein precede retinoic acid-induced apoptosis in androgen-dependent LNCaP cells and their androgen-independent derivative. 1022 52

Mdm2 is a nuclear phosphoprotein which functions as a negative feedback regulator of the p53 tumor suppressor gene. In this study, we investigated the alteration of Mdm2 and p53 in three human cancer cell lines containing either a wild-type or mutant p53 gene after treatment with Adriamycin (doxorubicin, ADR), a DNA damaging agent. We found that human breast cancer MCF-7 cells containing wild-type p53 were much more susceptible to ADR compared to human breast cancer MDA-MB-231 and human prostate cancer Du-145 cells which contain mutant p53. ADR resulted in a significant dose-dependent accumulation of p53 protein in MCF-7 cells, whereas little or no influence was observed on p53 protein of the two mutant p53 cell lines. However, a significant down-regulation of Mdm2 at protein and mRNA levels was observed in these three cell lines following ADR treatment. Moreover, the decrease of Mdm2 was in both a dose- and time-dependent manner. It is interestingly noted that 5 microM is a critical dose for significant down-regulation of the Mdm2 protein. Selected proteasome inhibitors did not rescue the ADR-caused decline in the expression of Mdm2 protein. Therefore, our present results reveal that ADR can induce a down-regulation of Mdm2 via a p53-independent pathway in human cancer cells and the ubiquitin-proteasome degradation mechanism may not be involved in the decreased expression of Mdm2 protein.
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PMID:P53-independent down-regulation of Mdm2 in human cancer cells treated with adriamycin. 1077 10

Doxil, a doxorubicin formulation of polyethylene glycol-coated liposomes, has anti-tumor activity against Kaposi's sarcoma and other solid tumors with mild myelosuppression, minimal hair loss and a low risk of cardiotoxicity. Non-liposomal doxorubicin has modest activity in hormone-refractory prostate cancer (HRPC) with considerable toxicity. A pilot study of Doxil was conducted in 15 patients with HRPC. Doxil was administered i.v. using two regimes of equal dose intensity, either 45 mg/m2 every 3 weeks or 60 mg/m2 every 4 weeks. Plasma levels of doxorubicin were analyzed in 10 patients. The most common side effect was stomatitis with a higher incidence at the 60 mg/m2 dose level. In contrast, hand-foot syndrome was more frequent and severe in patients treated with the 3 week schedule of 45 mg/m2. Three patients responded to treatment (based on objective response in one patient and reduction of PSA level greater than 50% in the other two) and two patients had stable disease, all of them receiving 60 mg/m2. Pharmacokinetic analysis shows a proportional increase of plasma drug levels with dose and the characteristic long circulation time of Doxil with half-lives in the range of 3 days, somewhat longer than previously reported. In conclusion, Doxil at 60 mg/m2 every 4 weeks appears to be active against HRPC, but severe mucocutaneous toxicities prevented further investigation of this regime.
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PMID:Doxil (Caelyx): an exploratory study with pharmacokinetics in patients with hormone-refractory prostate cancer. 1078 95

The anti-neoplastic properties of an Selenium compound were studied in vitro on several tumor cell lines: Breast (MCF-7, MCF-10, SKBR-3, BCAP37), Lung (RH2), Prostate (LNCap and PC-3), Colon (T84, Caco-2), Small Intestine (HCF8), and Liver (HepG2). We also examined additive or synergistic effect of Selenium in combination with standard anti-cancer drugs, Adriamycin (Doxorubicin) and Taxol. The effect of Selenium was assessed by apoptosis; DNA synthesis; growth rate by MTT assay; uptake of amino acid MeAIB by System A; and morphological changes. Our results demonstrate that MCF-7 and SKBR-3 showed increase in apoptosis as measured by DNA fragmentation and increase in "rounded" cells and membrane "blebbing", decrease in MeAIB uptake, and decrease in DNA synthesis. These changes were Selenium dose dependent with optimal inhibition at Selenium concentration between 4 and 40 ng/ml after 72 hrs of treatment. Similar observations were made with RH2, HCF8, Caco-2, and HepG2 cells. In contrast, LNCap, PC-3, and T-84 were not significantly affected by Selenium. However, addition of Adriamycin or Taxol in combination with Selenium caused small but significant inhibition of prostate cancer cells LNCap and PC-3. Addition of chemotherapeutic agents either Taxol or Doxorubicin with Selenium caused further inhibition of MCF-7, SKBR-3, RH2, HCF8, and HepG2 cells. In conclusion, Selenium has a significant anti-neoplastic effect on breast, lung, liver, and small intestinal tumor cells. Supplementation of Selenium enhanced chemotherapeutic effect of Taxol and Doxorubicin in these cells beyond that seen with the chemotherapeutic drugs used alone. These in vitro studies on several cancer cell lines suggest a potential benefit of Selenium-enhancement of anticancer effects other systems, and therefore offer further relevance to clinical trials efforts.
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PMID:Effect of selenium in combination with Adriamycin or Taxol on several different cancer cells. 1092 49

A high-throughput screening assay was designed to select compounds that inhibit the growth of cultured mammalian cells. After screening more than 60,000 compounds, A-105972 was identified and selected for further testing. A-105972 is a small molecule that inhibits the growth of breast, central nervous system, colon, liver, lung, and prostate cancer cell lines, including multidrug-resistant cells. The cytotoxic IC50 values of A-105972 were between 20 and 200 nM, depending on the specific cell type. The potency of A-105972 is similar in cells expressing wild-type or mutant p53. A majority of cells treated with A-105972 were trapped in the G2-M phases, suggesting that A-105972 inhibits the progression of the cell cycle. Using [3H]A-105972, we found that A-105972 bound to purified tubulin. Unlabeled A-105972 competed with [3H]A-105972 binding with an IC50 value of 3.6 microL. Colchicine partially inhibited [3H]A-105972 binding with an IC50 value of approximately 90 microM, whereas paclitaxel and vinblastine had no significant effect. Tumor cells treated with A-105972 were observed to contain abnormal microtubule arrangement and apoptotic bodies. DNA ladder studies also indicated that A-105972 induced apoptosis. A-105972 caused a mobility shift of bcl-2 on SDS-PAGE, suggesting that A-105972 induced bcl-2 phosphorylation. A-105972 treatment increased the life span of mice inoculated with B16 melanoma, P388 leukemia, and Adriamycin-resistant P388. These results suggest that A-105972 is a small molecule that interacts with microtubules, arrests cells in G2-M phases, and induces apoptosis in both multidrug resistance-negative and multidrug resistance-positive cancer cells. A-105972 and its analogues may be useful for treating cell proliferative disorders such as cancer.
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PMID:Identification and characterization of A-105972, an antineoplastic agent. 1124 55

Prostate cancer (CaP) is the most commonly diagnosed cancer of aging men and the second leading cause of male cancer death in the United States. At present, no effective therapy is available for treating hormone independent CaP. Since Bcl2 is believed to play a role in protecting CaP cells from apoptosis, we investigated the effects of down-regulating Bcl2 expression on CaP cells. Genetically engineered LNCaP sublines were established by stably transfecting LNCaP cells with BCL2 antisense (BCL2-AS) transcript-expressing plasmids. Western blotting analysis showed that intracellular Bcl2 protein was decreased by 50-60% in BCL2-AS-transfected LNCaP cells. Expression of the antisense transcripts resulted in 50% growth inhibition of LNCaP cells in response to androgen withdrawal and markedly sensitized these cells to Adriamycin-induced apoptosis. These results suggest that down-regulation of Bcl2 protein using BCL2-AS transcripts could be exploited for improved treatment of advanced CaP.
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PMID:BCL2 antisense transcripts decrease intracellular Bcl2 expression and sensitize LNCaP prostate cancer cells to apoptosis-inducing agents. 1177 59

Paclitaxel, a natural anticancer drug, has gained widespread acceptance as an active broad-spectrum antitumor agent, including its use in urological malignancies, particularly urothelial tract cancer and testicular cancer. The mechanism of action, based on the premature stabilization of the microtubule assembly with disruption of the cytoskeletal framework, is completely different from those of DNA-damaging agents, e.g., cisplatin and ifosfamide. As a single agent, paclitaxel is one of the most active drugs in metastatic bladder cancer, with an overall response rate of 40-50% being obtained in previously untreated patients. These promising single-agent results have prompted the use of combination regimens including, in particular, cisplatin and paclitaxel. A high degree of activity for the cisplatin-paclitaxel combination as reflected by responses in 50-80% of patients, including a substantial number of complete responses (> 30%), has been identified. The role of other agents such as vinorelbine, methotrexate, 5-fluorouracil, or ifosfamide as additions to this two-drug combination currently remains open. The combination of paclitaxel plus ifosfamide or vinorelbine in the absence of a platinum derivative has yielded rather disappointing results. Of particular interest may be the combination of paclitaxel and carboplatin. Both drugs can be given to patients with impaired renal function. Overall response rates of 45-60% have been reported in phase II studies. The so-called platelet-sparing effect of paclitaxel given in combination with carboplatin has resulted in a surprisingly low frequency of myelotoxicity, particularly thrombocytopenia. The combination of paclitaxel with carboplatin is being compared in an ongoing trial against the current standard MVAC regimen (methotrexate/vinblastine/Adriamycin/cisplatin) in patients with metastatic disease. Furthermore, the activity of paclitaxel-based combinations is currently being explored in the neoadjuvant setting in phase II studies, and the potential for the combination with the other new promising agent--gemcitabine--will be evaluated in a phase I setting. In prostate cancer, estramustine phosphate is widely used as palliative treatment for patients with hormone-refractory disease. In vitro synergistic activity has been observed between estramustine and paclitaxel in prostate-cancer cell lines, although paclitaxel has not demonstrated single-agent activity in patients with hormone-refractory prostate cancer. In clinical trials the combination of the two agents was associated with increased gastrointestinal toxicity. The addition of etoposide as a third drug has yielded prostate-specific antigen (PSA)-response rates of > 50%, but data on quality of life and survival time have not been reported for these combinations. A true clinical role for paclitaxel in prostate cancer has therefore not been established. Paclitaxel has finally demonstrated single-agent activity in relapsed and/or cisplatin-refractory testicular cancer in recent phase II trials, indicating different mechanisms of resistance to cisplatin and paclitaxel. These results have formed the rationale for the introduction of paclitaxel as part of combination chemotherapy regimens in patients with relapsed but chemosensitive testicular cancer. Preliminary results demonstrate that paclitaxel can be safely included into these conventional-dose combination regimens. When it is used prior to high-dose chemotherapy, sufficient numbers of peripheral blood stem cells (PBSCs) for high-dose therapy can be collected. The final role of paclitaxel in risk-adapted chemotherapeutic strategies in testicular cancer is not defined, but it appears that paclitaxel-based combinations can achieve a substantial response rate in patients with relapsed disease.
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PMID:Recent strategies for the use of paclitaxel in the treatment of urological malignancies. 1207 32

Patients with clinical T3 or T4 prostate cancer or with elevated serum prostate-specific antigen (PSA) levels greater than 40 ng/ml are at high risk of failure with primary treatment. Chemotherapy administered at the time of diagnosis may decrease the risk of recurrence. Patients with high risk localized prostate cancer were treated with two cycles of liposomal doxorubicin (Doxil) at 50 mg/m2 every 28 days. Patients were assessed for response by digital rectal examination (DRE), PSA, and endorectal magnetic resonance imaging (MRI) (erMRI). Patients were then treated with androgen ablative therapy and prostate radiotherapy. Seven patients were treated. Three patients had T3 disease, and 4 patients had T2b disease with either PSA greater than 40 ng/ml or erMRI evidence of seminal vesicle involvement or extracapsular disease. Median PSA was 29.4 ng/ml. None of the seven patients experienced a significant response, as measured by changes in DRE, PSA, or erMRI. Toxicity was significant, with 4 of 7 patients developing skin toxicity. All seven patients responded to androgen ablative therapy and prostate irradiation. Neoadjuvant liposomal doxorubicin demonstrates no apparent activity and significant toxicity. New strategies are needed to improve outcomes in high-risk prostate cancer.
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PMID:Neoadjuvant doxil chemotherapy prior to androgen ablation plus radiotherapy for high-risk localized prostate cancer: feasibility and toxicity. 1279 7

The available monolayer culture systems for the study of bone metastases constitute a suboptimal simulation of the in vivo pathophysiology of bone metastases, and therefore, do not provide sufficient information to assess the morphologic evidence of bone reaction to cancer cells, the nature of cell-specific mediators of osteolysis and osteoplasia and the response to treatment. Therefore, we have developed a three-dimensional (3-D) type I collagen gel system that allows co-culture of human osteoblasts (MG-63) with cancer cells, such as MCF-7, MDA-MB-231 or ZR-75 breast cancer cells, PC-3 prostate cancer, KLE endometrial cancer cells and Calu-1 lung cancer cells. We used type I collagen purified from rat tail tendons and the 3-D system was prepared by mixing MG-63 cells with type I collagen in 24-well plates. The 3-D system was inoculated with cancer cells and processed with standard cell culture procedures. After 1 week of culture, the matrix gel was fixed with formalin and embedded in paraffin. Serial sections were stained with trichrome Masson stain and modified Masson-Goldner stain, as well as analyzed by in situ hybridization, immunohistochemistry and the TUNEL technique for semi-quantitative detection of apoptotic cell death, assessing the response to adriamycin therapy. The inoculation of PC-3 cells in this collagen matrix produced a blastic reaction, documented by an increased number of MG-63 cells and increased density of type I collagen. The human KLE cells and inoculation of cell-free media produced no reaction, while ZR-75, MCF-7 and Calu-1 cells produced local degradation of the collagen matrix. In situ hybridization revealed the expression of Insulin-like growth factor 1 (IGF-1) and urokinase-type plasminogen activator (uPA) mRNA, while immunohistochemistry detected differential expression of uPA and cathepsin D. Adriamycin induced apoptotic cell death in prostate cancer cells and estrogen receptor negative (ER-) MDA-MB-231 breast cancer cells, while adriamycin did not induce apoptosis but cytostasis in ER+ MCF-7 cells. The adriamycin-induced apoptosis was inhibited by co-culture with osteoblast-like cells (MG-63). We conclude that this 3-D culture system is a useful in vitro model allowing the analysis of local mediators of osteolytic and osteoblastic reactions to bone metastases and treatment response.
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PMID:Three-dimensional type I collagen co-culture systems for the study of cell-cell interactions and treatment response in bone metastases. 1575 11

Advanced and hormone-refractory prostate cancer has long been considered as a chemoresistant disease. Recently, it was found that 14-3-3sigma expression increases as prostate tumor progresses, and that 14-3-3sigma contributes significantly to drug resistance in breast cancers. We, thus, hypothesized that advanced and hormone-refractory prostate cancers may have an increased level of 14-3-3sigma, which in turn may contribute to drug resistance in advanced and hormone-refractory prostate cancers. In this study, we tested this hypothesis and found that, indeed, the expression level of 14-3-3sigma in androgen-independent prostate cancer cell lines DU145, PC3, and CWR22RV are much higher than that in the androgen-dependent cell line LNCaP, and that the androgen-independent cells are more resistant to mitoxantrone and Adriamycin than the androgen-dependent cells. Depleting 14-3-3sigma expression in DU145 and CWR22RV by RNA interference significantly sensitized these cells to mitoxantrone and Adriamycin by abrogating G2-M checkpoint and increasing apoptosis, whereas restoring 14-3-3sigma expression in LNCaP cells enhanced drug resistance. We also showed that 14-3-3sigma deficiency caused nuclear localization of Cdc2 and dephosphorylation of the Tyr15 residue upon DNA damage. Based on these studies, we propose that therapeutic intervention targeting 14-3-3sigma may be useful for sensitizing hormone-refractory prostate cancers to chemotherapy by both G2-M checkpoint abrogation and apoptosis enhancement.
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PMID:Sensitizing hormone-refractory prostate cancer cells to drug treatment by targeting 14-3-3sigma. 1664 60


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