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NF-kappaB activation enhances cell death by antimitotic drugs in human prostate cancer cells.

Parrondo R, de las Pozas A, Reiner T, Rai P, Perez-Stable C - Mol. Cancer (2010)

Bottom Line: In castration-resistant DU145 and PC3 cells, Doc and 2ME2 had little effect on the high basal NF-kappaB activity and addition of parthenolide did not enhance cell death.Our data suggest that the combination of antimitotic drugs with NF-kappaB inhibitors will have antagonistic effects in a common type of PC cell typical of LNCaP.However, combination strategies utilizing antimitotic drugs with BA, an activator of NF-kappaB, will universally enhance cell death in PC cells, notably in the aggressive, castration-resistant variety that does not respond to conventional therapies.

View Article: PubMed Central - HTML - PubMed

Affiliation: Geriatric Research, Education, and Clinical Center and Research Service, Bruce W, Carter Veterans Affairs Medical Center, Miami, FL 33125, USA.

ABSTRACT

Background: NF-kappaB is a transcription factor that promotes inhibition of apoptosis and resistance to chemotherapy. It is commonly believed that inhibition of NF-kappaB activity can increase sensitivity of cancer cells to chemotherapy. However, there is evidence that NF-kappaB activation can sensitize cells to apoptosis and that inhibition of NF-kappaB results in resistance to chemotherapy. In prostate cancer, it is not clear in the different cell types (androgen-dependent and castration-resistant) if activation or inhibition of NF-kappaB is required for stimulation of apoptosis by chemotherapy.

Results: Our data indicate that the response of prostate cancer (PC) cells to the antimitotic drugs docetaxel (Doc) and 2-methoxyestradiol (2ME2) is dependent on the levels of NF-kappaB activity. In androgen-dependent LNCaP cells, Doc and 2ME2 treatment increased the low basal NF-kappaB activity, as determined by Western blot analysis of phospho-IkappaBalpha/p65, NF-kappaB promoter reporter assays, and p65 localization. Treatment of LNCaP cells with parthenolide, a pharmacologic inhibitor of NF-kappaB, or introduction of dominant-negative IkappaBalpha, or an shRNA specific for p65, a component of the NF-kappaB heterodimer, blocked apoptosis induced by Doc and 2ME2. In castration-resistant DU145 and PC3 cells, Doc and 2ME2 had little effect on the high basal NF-kappaB activity and addition of parthenolide did not enhance cell death. However, the combination of Doc or 2ME2 with betulinic acid (BA), a triterpenoid that activates NF-kappaB, stimulated apoptosis in LNCaP and non-apoptotic cell death in DU145 and PC3 cells. Increased sensitivity to cell death mediated by the Doc or 2ME2 + BA combination is likely due to increased NF-kappaB activity.

Conclusions: Our data suggest that the combination of antimitotic drugs with NF-kappaB inhibitors will have antagonistic effects in a common type of PC cell typical of LNCaP. However, combination strategies utilizing antimitotic drugs with BA, an activator of NF-kappaB, will universally enhance cell death in PC cells, notably in the aggressive, castration-resistant variety that does not respond to conventional therapies.

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NF-κB inhibitor parthenolide blocks 2ME2 and Doc-mediated apoptosis in LNCaP cells. DAPI apoptosis analysis (% condensed fragmented nuclei) showing that parthenolide (P; 10 μM) blocks 2ME2 (M; 5 μM) and Doc (D; 1 nM) apoptosis in LNCaP (72 h) cells. n = 7, four independent experiments; *, P < 6 × 10-4. Western blot analysis shows that P inhibits the M and D increase in cleaved PARP (72 h), P-IκBα/IκBα (24 h), P-p65/p65 (24 h), p53 (72 h), and the M/D decrease in XIAP (72 h). Coomassie blue stain of total protein is loading control.
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Figure 3: NF-κB inhibitor parthenolide blocks 2ME2 and Doc-mediated apoptosis in LNCaP cells. DAPI apoptosis analysis (% condensed fragmented nuclei) showing that parthenolide (P; 10 μM) blocks 2ME2 (M; 5 μM) and Doc (D; 1 nM) apoptosis in LNCaP (72 h) cells. n = 7, four independent experiments; *, P < 6 × 10-4. Western blot analysis shows that P inhibits the M and D increase in cleaved PARP (72 h), P-IκBα/IκBα (24 h), P-p65/p65 (24 h), p53 (72 h), and the M/D decrease in XIAP (72 h). Coomassie blue stain of total protein is loading control.

Mentions: To determine whether 2ME2- or Doc-mediated activation of NF-κB in LNCaP cells is important for stimulating apoptosis, we used the NF-κB inhibitor parthenolide [40]. Treatment of LNCaP cells with 10 μM parthenolide lowered apoptosis induced by 2ME2 or Doc, as determined by the DAPI apoptosis assay and decreased levels cleaved PARP protein (Fig. 3). Parthenolide lowered the 2ME2- or Doc-mediated increase in phospho-IκBα and phospho-p65, suggesting inhibition of NF-κB activity. These results indicate that 2ME2- or Doc-mediated increase in NF-κB activity is important for induction of apoptosis in LNCaP cells. Similar results were obtained in LN-AI cells (result not shown).


NF-kappaB activation enhances cell death by antimitotic drugs in human prostate cancer cells.

Parrondo R, de las Pozas A, Reiner T, Rai P, Perez-Stable C - Mol. Cancer (2010)

NF-κB inhibitor parthenolide blocks 2ME2 and Doc-mediated apoptosis in LNCaP cells. DAPI apoptosis analysis (% condensed fragmented nuclei) showing that parthenolide (P; 10 μM) blocks 2ME2 (M; 5 μM) and Doc (D; 1 nM) apoptosis in LNCaP (72 h) cells. n = 7, four independent experiments; *, P < 6 × 10-4. Western blot analysis shows that P inhibits the M and D increase in cleaved PARP (72 h), P-IκBα/IκBα (24 h), P-p65/p65 (24 h), p53 (72 h), and the M/D decrease in XIAP (72 h). Coomassie blue stain of total protein is loading control.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2908581&req=5

Figure 3: NF-κB inhibitor parthenolide blocks 2ME2 and Doc-mediated apoptosis in LNCaP cells. DAPI apoptosis analysis (% condensed fragmented nuclei) showing that parthenolide (P; 10 μM) blocks 2ME2 (M; 5 μM) and Doc (D; 1 nM) apoptosis in LNCaP (72 h) cells. n = 7, four independent experiments; *, P < 6 × 10-4. Western blot analysis shows that P inhibits the M and D increase in cleaved PARP (72 h), P-IκBα/IκBα (24 h), P-p65/p65 (24 h), p53 (72 h), and the M/D decrease in XIAP (72 h). Coomassie blue stain of total protein is loading control.
Mentions: To determine whether 2ME2- or Doc-mediated activation of NF-κB in LNCaP cells is important for stimulating apoptosis, we used the NF-κB inhibitor parthenolide [40]. Treatment of LNCaP cells with 10 μM parthenolide lowered apoptosis induced by 2ME2 or Doc, as determined by the DAPI apoptosis assay and decreased levels cleaved PARP protein (Fig. 3). Parthenolide lowered the 2ME2- or Doc-mediated increase in phospho-IκBα and phospho-p65, suggesting inhibition of NF-κB activity. These results indicate that 2ME2- or Doc-mediated increase in NF-κB activity is important for induction of apoptosis in LNCaP cells. Similar results were obtained in LN-AI cells (result not shown).

Bottom Line: In castration-resistant DU145 and PC3 cells, Doc and 2ME2 had little effect on the high basal NF-kappaB activity and addition of parthenolide did not enhance cell death.Our data suggest that the combination of antimitotic drugs with NF-kappaB inhibitors will have antagonistic effects in a common type of PC cell typical of LNCaP.However, combination strategies utilizing antimitotic drugs with BA, an activator of NF-kappaB, will universally enhance cell death in PC cells, notably in the aggressive, castration-resistant variety that does not respond to conventional therapies.

View Article: PubMed Central - HTML - PubMed

Affiliation: Geriatric Research, Education, and Clinical Center and Research Service, Bruce W, Carter Veterans Affairs Medical Center, Miami, FL 33125, USA.

ABSTRACT

Background: NF-kappaB is a transcription factor that promotes inhibition of apoptosis and resistance to chemotherapy. It is commonly believed that inhibition of NF-kappaB activity can increase sensitivity of cancer cells to chemotherapy. However, there is evidence that NF-kappaB activation can sensitize cells to apoptosis and that inhibition of NF-kappaB results in resistance to chemotherapy. In prostate cancer, it is not clear in the different cell types (androgen-dependent and castration-resistant) if activation or inhibition of NF-kappaB is required for stimulation of apoptosis by chemotherapy.

Results: Our data indicate that the response of prostate cancer (PC) cells to the antimitotic drugs docetaxel (Doc) and 2-methoxyestradiol (2ME2) is dependent on the levels of NF-kappaB activity. In androgen-dependent LNCaP cells, Doc and 2ME2 treatment increased the low basal NF-kappaB activity, as determined by Western blot analysis of phospho-IkappaBalpha/p65, NF-kappaB promoter reporter assays, and p65 localization. Treatment of LNCaP cells with parthenolide, a pharmacologic inhibitor of NF-kappaB, or introduction of dominant-negative IkappaBalpha, or an shRNA specific for p65, a component of the NF-kappaB heterodimer, blocked apoptosis induced by Doc and 2ME2. In castration-resistant DU145 and PC3 cells, Doc and 2ME2 had little effect on the high basal NF-kappaB activity and addition of parthenolide did not enhance cell death. However, the combination of Doc or 2ME2 with betulinic acid (BA), a triterpenoid that activates NF-kappaB, stimulated apoptosis in LNCaP and non-apoptotic cell death in DU145 and PC3 cells. Increased sensitivity to cell death mediated by the Doc or 2ME2 + BA combination is likely due to increased NF-kappaB activity.

Conclusions: Our data suggest that the combination of antimitotic drugs with NF-kappaB inhibitors will have antagonistic effects in a common type of PC cell typical of LNCaP. However, combination strategies utilizing antimitotic drugs with BA, an activator of NF-kappaB, will universally enhance cell death in PC cells, notably in the aggressive, castration-resistant variety that does not respond to conventional therapies.

Show MeSH
Related in: MedlinePlus