In vitro studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol

<p>Abstract</p> <p>Background</p> <p>As the majority of prostate cancers (PC) express estrogen receptors, we evaluated the combination of radiation and estrogenic stimulation (estrogen and genistein) on the radiosensitivity of PC cells in vitro.</p> <p>Methods</p> <p>PC cells LNCaP (androgen-sensitive) and PC-3 (androgen-independent) were evaluated. Estrogen receptor (ER) expression was analyzed by means of immunostaining. Cells were incubated in FCS-free media with genistein 10 μM and estradiol 10 μM 24 h before irradiation and up to 24 h after irradiation. Clonogenic survival, cell cycle changes, and expression of p21 were assessed.</p> <p>Results</p> <p>LNCaP expressed both ER-α and ER-β, PC-3 did not. Incubation of LNCaP and PC-3 with genistein resulted in a significant reduction of clonogenic survival. Incubation with estradiol exhibited in low concentrations (0.01 μM) stimulatory effects, while higher concentrations did not influence survival. Both genistein 10 μM and estradiol 10 μM increased low-dose hyper-radiosensitivity [HRS] in LNCaP, while hormonal incubation abolished HRS in PC-3. In LNCaP cells hormonal stimulation inhibited p21 induction after irradiation with 4 Gy. In PC-3 cells, the proportion of cells in G2/M was increased after irradiation with 4 Gy.</p> <p>Conclusion</p> <p>We found an increased HRS to low irradiation doses after incubation with estradiol or genistein in ER-α and ER-β positive LNCaP cells. This is of high clinical interest, as this tumor model reflects a locally advanced, androgen dependent PC. In contrast, in ER-α and ER-β negative PC-3 cells we observed an abolishing of the HRS to low irradiation doses by hormonal stimulation. The effects of both tested compounds on survival were ER and p53 independent. Since genistein and estradiol effects in both cell lines were comparable, neither ER- nor p53-expression seemed to play a role in the linked signalling. Nevertheless both compounds targeted the same molecular switch. To identify the underlying molecular mechanisms, further studies are needed.</p

Studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol-4

To fit the low-dose hyper-radiosensitivity region of the control curves while the genistein and estradiol curves followed a linear-quadratic equation. Incubation with genistein and estradiol abolished the HRS to low irradiation doses seen in the controls (genistein 10 μM vs. controls: 0.4 Gy: p < 0.01; 0.6 Gy: p = 0.027; estradiol 10 μM vs. controls: 0.4 Gy: p < 0.001; 0.6 Gy: p < 0.001). At and above 2 Gy there were no significant differences between the surviving clones after hormonal incubation and controls.<p><b>Copyright information:</b></p><p>Taken from "studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol"</p><p>http://www.ro-journal.com/content/3/1/19</p><p>Radiation Oncology (London, England) 2008;3():19-19.</p><p>Published online 14 Jul 2008</p><p>PMCID:PMC2490684.</p><p></p

Studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol-7

Oma cell line that expresses both ER-α and ER-β, whereas BG-1 is an ovarian cell that does not express these receptors. Expression of the receptors reflects a brown staining. For easier analysis, staining of the nuclei with DAB was not performed in the presented samples of LNCaP and PC-3. While LNCaP cells showed expression of ER-α and ER-β, PC-3 cells did not.<p><b>Copyright information:</b></p><p>Taken from "studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol"</p><p>http://www.ro-journal.com/content/3/1/19</p><p>Radiation Oncology (London, England) 2008;3():19-19.</p><p>Published online 14 Jul 2008</p><p>PMCID:PMC2490684.</p><p></p

Studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol-5

. In controls incubated in FCS containing media and in controls incubated in media with FCS-withdrawal there was a induction of p21 expression. The same was seen in cells after incubation with low doses of estradiol (0.01 μM) and genistein (0.01 μM). After incubation with high concentrations of estradiol (10 μM) and genistein (10 μM) the induction of p21 was completely abolished.<p><b>Copyright information:</b></p><p>Taken from "studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol"</p><p>http://www.ro-journal.com/content/3/1/19</p><p>Radiation Oncology (London, England) 2008;3():19-19.</p><p>Published online 14 Jul 2008</p><p>PMCID:PMC2490684.</p><p></p

Studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol-2

Increased colony formation significantly (LNCaP: p < 0.0001; PC-3: p < 0.0001), while higher concentrations of estradiol did not influence colony formation in comparison to untreated controls.<p><b>Copyright information:</b></p><p>Taken from "studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol"</p><p>http://www.ro-journal.com/content/3/1/19</p><p>Radiation Oncology (London, England) 2008;3():19-19.</p><p>Published online 14 Jul 2008</p><p>PMCID:PMC2490684.</p><p></p

Studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol-1

Tion in colony forming is observed after incubation with genistein. Colony formation was reduced to 50% of the controls in LNCaP afer incubation with genistein 0.01 μM (p = 0.004). Higher genistein concentrations (0.1 μM and 10 μM) did not further suppress clonogenic survival. In PC-3 incubation with genistein 0.1 μM decreased colony formation to 75% of the controls (p = 0.027), higher concentrations reduced clonogenic survival further (10 μM: p < 0.001; 25 μM: p < 0.001).<p><b>Copyright information:</b></p><p>Taken from "studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol"</p><p>http://www.ro-journal.com/content/3/1/19</p><p>Radiation Oncology (London, England) 2008;3():19-19.</p><p>Published online 14 Jul 2008</p><p>PMCID:PMC2490684.</p><p></p

Studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol-3

To fit the low-dose hyper-radiosensitivity region of all curves. Incubation with genistein 10 μM and estradiol 10 μM enlarged the area of radiohypersensitivity to doses of up to 1 Gy when compared to untreated controls. p-values for LNCaP control vs. genistein 10 μM were p < 0.05 at the following dose points: 0.4 Gy, 0.5 Gy, 0.6 Gy, 0.8 Gy, 1 Gy. No significant differences were found between the clonogenic survival curves at 0 Gy, 0.2 Gy, 2 Gy, 3 Gy and 4 Gy. p-values for LNCaP controls vs. estradiol 10 μM were p < 0.05 at the following dose points: 0.4 Gy, 0.6 Gy, 0.8 Gy, 1 Gy and 3 Gy. No significant differences were found at 0 Gy, 0.5 Gy, 2 Gy and 4 Gy.<p><b>Copyright information:</b></p><p>Taken from "studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol"</p><p>http://www.ro-journal.com/content/3/1/19</p><p>Radiation Oncology (London, England) 2008;3():19-19.</p><p>Published online 14 Jul 2008</p><p>PMCID:PMC2490684.</p><p></p

Studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol-0

Oma cell line that expresses both ER-α and ER-β, whereas BG-1 is an ovarian cell that does not express these receptors. Expression of the receptors reflects a brown staining. For easier analysis, staining of the nuclei with DAB was not performed in the presented samples of LNCaP and PC-3. While LNCaP cells showed expression of ER-α and ER-β, PC-3 cells did not.<p><b>Copyright information:</b></p><p>Taken from "studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol"</p><p>http://www.ro-journal.com/content/3/1/19</p><p>Radiation Oncology (London, England) 2008;3():19-19.</p><p>Published online 14 Jul 2008</p><p>PMCID:PMC2490684.</p><p></p

Studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol-6

Ignated probes were irradiated with 4 Gy. In the following time, every 6 h probes were stained with DAPI and analyzed in a flow cytometer up to point "72 h". Every result reflects 3 independent assays. Proportion of cells in G0/G1 is symbolised by a bar, G2/M by a white bar and S-phase by a black bar. In the controls 15% of the cells were in S-phase, 65% in G0/G1 and 20% in G2/M. In the following, the S-phase was reduced to 5%, while G0/G1 increased to 73%. The proportion of cells in G2/M showed minimal changes. After incubation with genistein 10 μM no significant differences when compared to untreated controls were observed. After irradiation with 4 Gy the proportion of cells in G0/G1 decreased from 73% to 62%, in S-phase decreased from 8% to 3.6% and in G2/M phase increased from 21% to 34.3%. Similar results were observed after incubation with genistein 10 μM and irradiation with 4 Gy. In the controls 15% of the cells were in S-phase, 65% in G0/G1 and 20% in G2/M. In the following, the S-phase was reduced to 5%, while G0/G1 increased to 73%. The proportion of cells in G2/M was only minimal changes. After incubation with genistein 10 μM no significant differences when compared to untreated controls were observed. After irradiation with 4 Gy the proportion of cells in G0/G1 decreased from 73% to 62%, in S-phase decreased from 8% to 3.6% and in G2/M phase increased from 21% to 34.3%. Similar results were observed after incubation with genistein 10 μM and irradiation with 4 Gy.<p><b>Copyright information:</b></p><p>Taken from "studies on the modification of low-dose hyper-radiosensitivity in prostate cancer cells by incubation with genistein and estradiol"</p><p>http://www.ro-journal.com/content/3/1/19</p><p>Radiation Oncology (London, England) 2008;3():19-19.</p><p>Published online 14 Jul 2008</p><p>PMCID:PMC2490684.</p><p></p