Effects of gamma-radiation on cell growth, cycle arrest, death, and superoxide dismutase expression by DU 145 human prostate cancer cells

Gamma-irradiation (gamma-IR) is extensively used in the treatment of hormone-resistant prostate carcinoma. The objective of the present study was to investigate the effects of 60Co gamma-IR on the growth, cell cycle arrest and cell death of the human prostate cancer cell line DU 145. The viability of DU 145 cells was measured by the Trypan blue exclusion assay and the 3(4,5-dimethylthiazol-2-yl)-2,5,diphenyltetrazolium bromide test. Bromodeoxyuridine incorporation was used for the determination of cell proliferation. Cell cycle arrest and cell death were analyzed by flow cytometry. Superoxide dismutase (SOD), specifically CuZnSOD and MnSOD protein expression, after 10 Gy gamma-IR, was determined by Western immunoblotting analysis. gamma-IR treatment had a significant (P < 0.001) antiproliferative and cytotoxic effect on DU 145 cells. Both effects were time and dose dependent. Also, the dose of gamma-IR which inhibited DNA synthesis and cell proliferation by 50% was 9.7 Gy. Furthermore, gamma-IR induced cell cycle arrest in the G2/M phase and the percentage of cells in the G2/M phase was increased from 15% (control) to 49% (IR cells), with a nonsignificant induction of apoptosis. Treatment with 10 Gy gamma-IR for 24, 48, and 72 h stimulated CuZnSOD and MnSOD protein expression in a time-dependent manner, approximately by 3- to 3.5-fold. These data suggest that CuZnSOD and MnSOD enzymes may play an important role in the gamma-IR-induced changes in DU 145 cell growth, cell cycle arrest and cell death.

Prostate-specific membrane antigen can promote in vivo osseous metastasis of prostate cancer cells in mice

Reports remain insufficient on whether and how prostate-specific membrane antigen (PSMA) can influence in vivo osseous metastasis of prostate cancer (PCa). In the present study, the authors induced stable expression of PSMA in mouse PCa cell line RM-1. In vivo osseous metastasis was induced in 37 6-week-old female C57BL/6 mice weighing 22.45 ± 0.456 g. RM-1 cells were actively injected into the femoral bone cavity, leading to bilateral dissymmetry of bone density in the femoral bone. Tumor cells were also detected in bone tissue by pathological examination. The impact on bone density was demonstrated by the significant difference between animals injected with RM-PSMA cells (0.0738 ± 0.0185 g/cm²) and animals injected with RM-empty plasmid cells (0.0895 ± 0.0241 g/cm²). The lytic bone lesion of the RM-PSMA group (68.4%) was higher than that of the control group (27.8%). Immunohistochemistry showed that the expression of both vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) was distinctly higher in the RM-PSMA group than in the control group, while ELISA and Western blot assay indicated that VEGF and MMP-9 were higher in the RM-PSMA group compared to the control group (in vitro). Thus, the present study proposed and then confirmed for the first time that PSMA can promote in vivo osseous metastasis of PCa by increasing sclerotic destruction of PCa cells. Further analyses also suggested that PSMA functions positively on the invasive ability of RM-1 by increasing the expression of MMP-9 and VEGF by osseous metastases in vivo

RNAi-mediated knockdown of pituitary tumor- transforming gene-1 (PTTG1) suppresses the proliferation and invasive potential of PC3 human prostate cancer cells

Pituitary tumor-transforming gene-1 (PTTG1) is a proto-oncogene that promotes tumorigenesis and metastasis in numerous cell types and is overexpressed in a variety of human tumors. We have demonstrated that PTTG1 expression was up-regulated in both human prostate cancer specimens and prostate cancer cell lines. For a more direct assessment of the function of PTTG1 in prostate tumorigenesis, RNAi-mediated knockdown was used to selectively decrease PTTG1 expression in PC3 human prostate tumor cells. After three weeks of selection, colonies stably transfected with PTTG1-targeted RNAi (the knockdown PC3 cell line) or empty vector (the control PC3 cell line) were selected and expanded to investigate the role of PTTG1 expression in PC3 cell growth and invasion. Cell proliferation rate was significantly slower (28%) in the PTTG1 knockdown line after 6 days of growth as indicated by an MTT cell viability assay (P < 0.05). Similarly, a soft agar colony formation assay revealed significantly fewer (66.7%) PTTG1 knockdown PC3 cell colonies than control colonies after three weeks of growth. In addition, PTTG1 knockdown resulted in cell cycle arrest at G1 as indicated by fluorescence-activated cell sorting. The PTTG1 knockdown PC3 cell line also exhibited significantly reduced migration through Matrigel in a transwell assay of invasive potential, and down-regulation of PTTG1 could lead to increased sensitivity of these prostate cancer cells to a commonly used anticancer drug, taxol. Thus, PTTG1 expression is crucial for PC3 cell proliferation and invasion, and could be a promising new target for prostate cancer therapy.

Comparative antiproliferation of human prostate cancer cells by ethanolic extracts of two groups of Brazilian propolis

Two groups of propolis, group 12, which was collected in the southeastern Brazil and group 13, which was collected in the northeastern Brazil, were examined for antiproliferation of primary malignant tumor (RC-58T/h/SA#4)-derived human prostate cancer cells and human prostate epithelial cells. The strongest inhibition of RC-58T/h/SA#4 cells was observed in propolis group 13 extracts, whereas moderate growth inhibition was observed in human prostate epithelial cells in comparison with group 12. It can be said that the Brazilian propolis of group 13 contains important chemical ingredients.

Inhibition of cytohesin-1 by siRNA leads to reduced IGFR signaling in prostate cancer

To explore how cytohesin-1 (CYTH-1) small interfering RNA (siRNA) influences the insulin-like growth factor receptor (IGFR)-associated signal transduction in prostate cancer, we transfected human prostate cancer PC-3 cell lines with liposome-encapsulatedCYTH-1 siRNA in serum-free medium and exposed the cells to 100 nM IGF-1. The mRNA and protein levels of the signal molecules involved in the IGFR signaling pathways were determined by real-time PCR and detected by Western blotting. The relative mRNA levels of CYTH-1, c-Myc, cyclinD1 and IGF-1R (CYTH-1 siRNA group vs scrambled siRNA group) were 0.26 vs 0.97, 0.34 vs 1.06, 0.10 vs 0.95, and 0.27 vs 0.41 (P < 0.05 for all), respectively. The relative protein levels of CYTH-1, pIGF-1R, pIRS1, pAkt1, pErk1, c-Myc, and cyclinD1 (CYTH-1 siRNA group vsscrambled siRNA group) were 0.10 vs 1.00 (30 min), 0.10 vs 0.98 (30 min), 0.04 vs 0.50 (30 min), 0.10 vs 1.00 (30 min), 0.10 vs 1.00 (30 min), 0.13 vs 0.85 (5 h), and 0.08 vs 0.80 (7 h), respectively. The tyrosine kinase activity of IGF-1R was associated with CYTH-1. The proliferative activity of PC-3 cells transfected with CYTH-1 siRNA was significantly lower than that of cells transfected with scrambled siRNA at 48 h (40.5 vs87.6%, P < 0.05) and at 72 h (34.5 vs 93.5%, P < 0.05). In conclusion, the interference of siRNA with cytohesin-1 leads to reduced IGFR signaling in prostate cancer; therefore, CYTH-1 might serve as a new molecular target for the treatment of prostate cancer.

Cytotoxic evaluation of essential oil from Casearia sylvestris Sw on human cancer cells and erythrocytes

A Casearia sylvestris (Flacourtiaceae) é uma planta popularmente conhecida como "guaçatonga" e é usada por povos indígenas da América do sul (Brasil, Peru e Bolivia) no tratamento de muitas doenças, incluindo câncer. Estudos citotóxicos mostraram que esta planta apresenta um possível e interessante potencial antitumoral devido à presença de moléculas chamadas casearinas. Além disso, a composição do óleo essencial mostrou uma alta concentração de sesquiterpenos de alto potencial citotóxico. Neste trabalho, nós verificamos que o óleo essencial da C. sylvestris apresentou uma boa citotoxicidade seletiva contra as linhagens de células tumorais HeLa, A-549 and HT-29 (CD50 63,3, 60,7 e 90,6 µg.ml-1, respectivamente) quando comparada às células não-tumorais Vero (CD50 210,1 µg.ml-1) e macrófagos de camundongos (CD50 234,0 µg.ml-1). Além disso, o óleo causou hemólise em sete diferentes tipos de eritrócitos, indicando que a C. sylvestris precisa ser usada com cuidado. Também foram testados padrões de β-cariofileno e α-humuleno que mostraram citotoxicidade similar àquelas apresentadas pelo óleo, indicando que estes compostos podem ser os responsáveis pelos efeitos tóxicos que foram observados neste estudo.

Prostatic paracoccidioidomycosis: differential diagnosis of prostate cancer

Symptomatic prostatic paracoccidioidomycosis (PCM) is a very rare condition; however, it may express as a typical benign prostatic hyperplasia or a simulating prostatic adenocarcinoma. This case report presents PCM mimicking prostatic adenocarcinoma. The purpose of this paper is to call the general physician's attention to this important differential diagnosis.

Relationship between two year PSA nadir and biochemical recurrence in prostate cancer patients treated with iodine-125 brachytherapy

Objective To evaluate the relationship between two year PSA nadir (PSAn) after brachytherapy and biochemical recurrence rates in prostate cancer patients. Materials and Methods In the period from January 1998 to August 2007, 120 patients were treated with iodine-125 brachytherapy alone. The results analysis was based on the definition of biochemical recurrence according to the Phoenix Consensus. Results Biochemical control was observed in 86 patients (71.7%), and biochemical recurrence, in 34 (28.3%). Mean PSAn was 0.53 ng/ml. The mean follow-up was 98 months. The patients were divided into two groups: group 1, with two year PSAn < 0.5 ng/ml after brachytherapy (74 patients; 61.7%), and group 2, with two year PSAn ≥ 0.5 ng/ml after brachytherapy (46 patients; 38.3%). Group 1 presented biochemical recurrence in 15 patients (20.3%), and group 2, in 19 patients (43.2%) (p < 0.02). The analysis of biochemical disease-free survival at seven years, stratified by the two groups, showed values of 80% and 64% (p < 0.02), respectively. Conclusion Levels of two year PSAn ≥ 0.5 ng/ml after brachytherapy are strongly correlated with a poor prognosis. This fact may help to identify patients at risk for disease recurrence.

The role of transrectal ultrasound in the diagnosis of prostate cancer: new contributions

Objective: The present study was aimed at evaluating the contribution of transrectal prostate ultrasound in the screening for prostate neoplasias and in the guidance of prostate biopsies. Materials and Methods: Prospective study developed over a one-year period. All the patients with indication for prostate biopsy were evaluated. Regardless of PSA values, the patients underwent ultrasound in order to identify suspicious nodules (confirmed by two observers). Sextant biopsy was subsequently performed. In cases of finding suspicious nodules, an additional puncture directed to such nodules was done. Results: In a total of 155 cases the prevalence of malignancy was of 53%. Suspicious nodules were detected in 34 patients, and 25 where malignant (positive predictive value of 74%). The specificity and sensitivity for suspicious nodules were 88% and 31% respectively. Comparatively with the randomly obtained sextant specimens, the rate of findings of neoplasia was higher in the specimens obtained with puncture directed to the nodule (p = 0.032). No statistically significant difference was observed in the Gleason score for both types of specimens (p = 0.172). Conclusion: The high positive predictive value and the high rate of findings of neoplasia in specimens of suspicious nodules should be taken into consideration in the future. The authors suggest a biopsy technique similar to the one described in the present study (sextant biopsy plus puncture directed to the suspicious nodule).

Strategies to evaluate the impact of rectal volume on prostate motion during three-dimensional conformal radiotherapy for prostate cancer

Abstract Objective: To evaluate the rectal volume influence on prostate motion during three-dimensional conformal radiotherapy (3D-CRT) for prostate cancer. Materials and Methods: Fifty-one patients with prostate cancer underwent a series of three computed tomography scans including an initial planning scan and two subsequent scans during 3D-CRT. The organs of interest were outlined. The prostate contour was compared with the initial CT images considering the anterior, posterior, superior, inferior and lateral edges of the organ. Variations in the anterior limits and volume of the rectum were assessed and correlated with prostate motion in the anteroposterior direction. Results: The maximum range of prostate motion was observed in the superoinferior direction, followed by the anteroposterior direction. A significant correlation was observed between prostate motion and rectal volume variation ( p = 0.037). A baseline rectal volume superior to 70 cm3 had a significant influence on the prostate motion in the anteroposterior direction ( p = 0.045). Conclusion: The present study showed a significant interfraction motion of the prostate during 3D-CRT with greatest variations in the superoinferior and anteroposterior directions, and that a large rectal volume influences the prostate motion with a cutoff value of 70 cm3. Therefore, the treatment of patients with a rectal volume > 70 cm3 should be re-planned with appropriate rectal preparation.

Synergism between dipyridamole and cisplatin in human breast cancer cells in vitro

Cisplatin is very effective in the treatment of metastatic breast cancer. However, the development of cellular resistance is a serious problem in cisplatin chemotherapy. In the present work, the effects of dipyridamole (DPM) on the cellular accumulation and cytotoxicity of cisplatin was studied in cisplatinsensitive (MDA/S) and cisplatinresistant (MDA/R) human breast cancer cells. In the presence of 30 µM DPM, the IC50 of cisplatin was reduced by 39% for both cell lines. Combination index analysis revealed that cisplatin and dipyridamole interact synergistically in MDA/R cells. In the MDA/S cells, the cellular accumulation of cisplatin increased by 57 ± 8% in the presence of 30 µM DPM. In the MDA/R cells, the cellular accumulation of cisplatin remained the same with or without 30 µM DPM. The results suggest that the enhancement of cisplatin cytotoxicity by DPM in MDA/S cells may be related to a DPM-induced increase in cisplatin accumulation, but the enhanced cytotoxicity in MDA/R cells employs a mechanism that does not involve an increase in the cellular accumulation of cisplatin.

Importance of bone assessment and prevention of osteoporotic fracture in patients with prostate cancer in the gonadotropic hormone analogues use

The antiandrogenic therapy (ADT) for prostate cancer represents an additional risk factor for the development of osteoporosis and fragility fractures. Still, bone health of patients on ADT is often not evaluated. After literature research we found that simple preventive measures can prevent bone loss in these patients, resulting in more cost-effective solutions to the public health system and family when compared to the treatment of fractures.

Induction of apoptosis in cancer cells by tumor necrosis factor and butyrolactone, an inhibitor of cyclin-dependent kinases

Induction of apoptosis by tumor necrosis factor (TNF) is modulated by changes in the expression and activity of several cell cycle regulatory proteins. We examined the effects of TNF (1-100 ng/ml) and butyrolactone I (100 µM), a specific inhibitor of cyclin-dependent kinases (CDK) with high selectivity for CDK-1 and CDK-2, on three different cancer cell lines: WEHI, L929 and HeLa S3. Both compounds blocked cell growth, but only TNF induced the common events of apoptosis, i.e., chromatin condensation and ladder pattern of DNA fragmentation in these cell lines. The TNF-induced apoptosis events were increased in the presence of butyrolactone. In vitro phosphorylation assays for exogenous histone H1 and endogenous retinoblastoma protein (pRb) in the total cell lysates showed that treatment with both TNF and butyrolactone inhibited the histone H1 kinase (WEHI, L929 and HeLa) and pRb kinase (WEHI) activities of CDKs, as compared with the controls. The role of proteases in the TNF and butyrolactone-induced apoptosis was evaluated by comparing the number and expression of polypeptides in the cell lysates by gel electrophoresis. TNF and butyrolactone treatment caused the disappearance of several cellular protein bands in the region between 40-200 kDa, and the 110- 90- and 50-kDa proteins were identified as the major substrates, whose degradation was remarkably increased by the treatments. Interestingly, the loss of several cellular protein bands was associated with the marked accumulation of two proteins apparently of 60 and 70 kDa, which may be cleavage products of one or more proteins. These findings link the decrease of cyclin-dependent kinase activities to the increase of protease activities within the growth arrest and apoptosis pathways induced by TNF.

P-glycoprotein-mediated resistance to chemotherapy in cancer cells: using recombinant cytosolic domains to establish structure-function relationships

Resistance to chemotherapy in cancer cells is mainly mediated by overexpression of P-glycoprotein (Pgp), a plasma membrane ATP-binding cassette (ABC) transporter which extrudes cytotoxic drugs at the expense of ATP hydrolysis. Pgp consists of two homologous halves each containing a transmembrane domain and a cytosolic nucleotide-binding domain (NBD) which contains two consensus Walker motifs, A and B, involved in ATP binding and hydrolysis. The protein also contains an S signature characteristic of ABC transporters. The molecular mechanism of Pgp-mediated drug transport is not known. Since the transporter has an extraordinarily broad substrate specificity, its cellular function has been described as a "hydrophobic vacuum cleaner". The limited knowledge about the mechanism of Pgp, partly due to the lack of a high-resolution structure, is well reflected in the failure to efficiently inhibit its activity in cancer cells and thus to reverse multidrug resistance (MDR). In contrast to the difficulties encountered when studying the full-length Pgp, the recombinant NBDs can be obtained in large amounts as soluble proteins. The biochemical and biophysical characterization of recombinant NBDs is shown here to provide a suitable alternative route to establish structure-function relationships. NBDs were shown to bind ATP and analogues as well as potent modulators of MDR, such as hydrophobic steroids, at a region close to the ATP site. Interestingly, flavonoids also bind to NBDs with high affinity. Their binding site partly overlaps both the ATP-binding site and the steroid-interacting region. Therefore flavonoids constitute a new promising class of bifunctional modulators of Pgp.