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Ribonucleotide reductase inhibition restores platinum-sensitivity in platinum-resistant ovarian cancer: a Gynecologic Oncology Group Study.

Kunos C, Radivoyevitch T, Abdul-Karim FW, Fanning J, Abulafia O, Bonebrake AJ, Usha L - J Transl Med (2012)

Bottom Line: The potent ribonucleotide reductase (RNR) inhibitor 3-aminopyridine-2-carboxyaldehyde-thiosemicarbazone (3-AP) was tested as a chemosensitizer for restored cisplatin-mediated cytotoxicity in platinum-resistant ovarian cancer.Pre-therapy ovarian cancer tissues were analyzed by immunohistochemistry for RNR subunit expression as an indicator of cisplatin plus 3-AP treatment response. 3-AP preceding cisplatin exposure in platinum-resistant ovarian cancer cells was not as effective as sequencing cisplatin plus 3-AP together in cell survival assays.Platinum-mediated DNA damage (i.e., γH2AX foci) resolved quickly after cisplatin-alone or 3-AP preceding cisplatin exposure, but persisted after a cisplatin plus 3-AP sequence.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Radiation Oncology, University Hospitals of Cleveland, Cleveland, OH 44106, USA. charles.kunos@UHhospitals.org

ABSTRACT

Background: The potent ribonucleotide reductase (RNR) inhibitor 3-aminopyridine-2-carboxyaldehyde-thiosemicarbazone (3-AP) was tested as a chemosensitizer for restored cisplatin-mediated cytotoxicity in platinum-resistant ovarian cancer.

Methods: Preclinical in vitro platinum-resistant ovarian cancer cell survival, RNR activity, and DNA damage assays were done after cisplatin or cisplatin plus 3-AP treatments. Six women with platinum-resistant ovarian cancer underwent four-day 3-AP (96 mg/m(2), day one to four) and cisplatin (25 mg/m(2), day two and three) infusions every 21 days until disease progression or adverse effects prohibited further therapy. Pre-therapy ovarian cancer tissues were analyzed by immunohistochemistry for RNR subunit expression as an indicator of cisplatin plus 3-AP treatment response.

Results: 3-AP preceding cisplatin exposure in platinum-resistant ovarian cancer cells was not as effective as sequencing cisplatin plus 3-AP together in cell survival assays. Platinum-mediated DNA damage (i.e., γH2AX foci) resolved quickly after cisplatin-alone or 3-AP preceding cisplatin exposure, but persisted after a cisplatin plus 3-AP sequence. On trial, 25 four-day overlapping 3-AP and cisplatin cycles were administered to six women (median 4.2 cycles per patient). 3-AP-related methemoglobinemia (range seven to 10%) occurred in two (33%) of six women, halting trial accrual.

Conclusions: When sequenced cisplatin plus 3-AP, RNR inhibition restored platinum-sensitivity in platinum-resistant ovarian cancers. 3-AP (96 mg/m(2)) infusions produced modest methemoglobinemia, the expected consequence of ribonucleotide reductase inhibitors disrupting collateral proteins containing iron.

Trial registry: ClinicalTrials.gov NCT00081276.

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Related in: MedlinePlus

3-aminopyridine-2-carboxyaldehyde-thiosemicarbazone (3-AP) effectively restored cisplatin sensitivity in “platinum-resistant” SKOV3 and OVCAR3 ovarian cancer cells. Panel A: Cells were treated with cisplatin (5 μM) and/or 3-AP (5 μM) for 6 hours and assayed by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) for cell mitochondrial viability at 24 hours after the start of cisplatin exposure. Compared to cisplatin alone, 3-AP alone, and 3-AP preceding cisplatin treatment, a significant cisplatin plus 3-AP interaction was found (P < 0.01, star). Panel B: 14-day clonogenic ovarian cancer cell survival was done using cisplatin (5 μM) and a wider therapeutic range of 3-AP (1, 5, or 10 μM). Here too a significant cisplatin plus 3-AP enhancement of cytotoxicity was seen (P < 0.001, star), when compared to 3-AP alone or 3-AP preceding cisplatin. Means (± standard error) are reported.
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Figure 4: 3-aminopyridine-2-carboxyaldehyde-thiosemicarbazone (3-AP) effectively restored cisplatin sensitivity in “platinum-resistant” SKOV3 and OVCAR3 ovarian cancer cells. Panel A: Cells were treated with cisplatin (5 μM) and/or 3-AP (5 μM) for 6 hours and assayed by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) for cell mitochondrial viability at 24 hours after the start of cisplatin exposure. Compared to cisplatin alone, 3-AP alone, and 3-AP preceding cisplatin treatment, a significant cisplatin plus 3-AP interaction was found (P < 0.01, star). Panel B: 14-day clonogenic ovarian cancer cell survival was done using cisplatin (5 μM) and a wider therapeutic range of 3-AP (1, 5, or 10 μM). Here too a significant cisplatin plus 3-AP enhancement of cytotoxicity was seen (P < 0.001, star), when compared to 3-AP alone or 3-AP preceding cisplatin. Means (± standard error) are reported.

Mentions: Single and combination agent 24-hour MTT assays of cisplatin and/or 3-AP are presented in Figure 4A. Cytoreduction of 3-AP plus cisplatin was significantly lower than untreated, 3-AP single agent, cisplatin single agent, and 3-AP prior to cisplatin treatment (P < 0.01, each). Wider therapeutic range 3-AP alone or added to cisplatin 14-day colony-forming assays are shown in Figure 4B. Sequencing 3-AP starting six hours prior to cisplatin treatment resulted in non-significant cell cytotoxicity compared to 3-AP alone (SKOV-3 P = 0.62; OVCAR P = 0.70). Co-exposure of cisplatin plus 3-AP significantly reduced platinum-resistant ovarian cancer cell survival (P < 0.001, each), suggesting restored platinum sensitivity when RNR is inhibited during an accumulation of cisplatin-mediated DNA damage. In these two cell lines that are mdr-1+ and should show relative insensitivity to platinum agents, cisplatin treatment alone resulted in minor cytotoxicity, as shown in Figure 4B.


Ribonucleotide reductase inhibition restores platinum-sensitivity in platinum-resistant ovarian cancer: a Gynecologic Oncology Group Study.

Kunos C, Radivoyevitch T, Abdul-Karim FW, Fanning J, Abulafia O, Bonebrake AJ, Usha L - J Transl Med (2012)

3-aminopyridine-2-carboxyaldehyde-thiosemicarbazone (3-AP) effectively restored cisplatin sensitivity in “platinum-resistant” SKOV3 and OVCAR3 ovarian cancer cells. Panel A: Cells were treated with cisplatin (5 μM) and/or 3-AP (5 μM) for 6 hours and assayed by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) for cell mitochondrial viability at 24 hours after the start of cisplatin exposure. Compared to cisplatin alone, 3-AP alone, and 3-AP preceding cisplatin treatment, a significant cisplatin plus 3-AP interaction was found (P < 0.01, star). Panel B: 14-day clonogenic ovarian cancer cell survival was done using cisplatin (5 μM) and a wider therapeutic range of 3-AP (1, 5, or 10 μM). Here too a significant cisplatin plus 3-AP enhancement of cytotoxicity was seen (P < 0.001, star), when compared to 3-AP alone or 3-AP preceding cisplatin. Means (± standard error) are reported.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3403898&req=5

Figure 4: 3-aminopyridine-2-carboxyaldehyde-thiosemicarbazone (3-AP) effectively restored cisplatin sensitivity in “platinum-resistant” SKOV3 and OVCAR3 ovarian cancer cells. Panel A: Cells were treated with cisplatin (5 μM) and/or 3-AP (5 μM) for 6 hours and assayed by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) for cell mitochondrial viability at 24 hours after the start of cisplatin exposure. Compared to cisplatin alone, 3-AP alone, and 3-AP preceding cisplatin treatment, a significant cisplatin plus 3-AP interaction was found (P < 0.01, star). Panel B: 14-day clonogenic ovarian cancer cell survival was done using cisplatin (5 μM) and a wider therapeutic range of 3-AP (1, 5, or 10 μM). Here too a significant cisplatin plus 3-AP enhancement of cytotoxicity was seen (P < 0.001, star), when compared to 3-AP alone or 3-AP preceding cisplatin. Means (± standard error) are reported.
Mentions: Single and combination agent 24-hour MTT assays of cisplatin and/or 3-AP are presented in Figure 4A. Cytoreduction of 3-AP plus cisplatin was significantly lower than untreated, 3-AP single agent, cisplatin single agent, and 3-AP prior to cisplatin treatment (P < 0.01, each). Wider therapeutic range 3-AP alone or added to cisplatin 14-day colony-forming assays are shown in Figure 4B. Sequencing 3-AP starting six hours prior to cisplatin treatment resulted in non-significant cell cytotoxicity compared to 3-AP alone (SKOV-3 P = 0.62; OVCAR P = 0.70). Co-exposure of cisplatin plus 3-AP significantly reduced platinum-resistant ovarian cancer cell survival (P < 0.001, each), suggesting restored platinum sensitivity when RNR is inhibited during an accumulation of cisplatin-mediated DNA damage. In these two cell lines that are mdr-1+ and should show relative insensitivity to platinum agents, cisplatin treatment alone resulted in minor cytotoxicity, as shown in Figure 4B.

Bottom Line: The potent ribonucleotide reductase (RNR) inhibitor 3-aminopyridine-2-carboxyaldehyde-thiosemicarbazone (3-AP) was tested as a chemosensitizer for restored cisplatin-mediated cytotoxicity in platinum-resistant ovarian cancer.Pre-therapy ovarian cancer tissues were analyzed by immunohistochemistry for RNR subunit expression as an indicator of cisplatin plus 3-AP treatment response. 3-AP preceding cisplatin exposure in platinum-resistant ovarian cancer cells was not as effective as sequencing cisplatin plus 3-AP together in cell survival assays.Platinum-mediated DNA damage (i.e., γH2AX foci) resolved quickly after cisplatin-alone or 3-AP preceding cisplatin exposure, but persisted after a cisplatin plus 3-AP sequence.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Radiation Oncology, University Hospitals of Cleveland, Cleveland, OH 44106, USA. charles.kunos@UHhospitals.org

ABSTRACT

Background: The potent ribonucleotide reductase (RNR) inhibitor 3-aminopyridine-2-carboxyaldehyde-thiosemicarbazone (3-AP) was tested as a chemosensitizer for restored cisplatin-mediated cytotoxicity in platinum-resistant ovarian cancer.

Methods: Preclinical in vitro platinum-resistant ovarian cancer cell survival, RNR activity, and DNA damage assays were done after cisplatin or cisplatin plus 3-AP treatments. Six women with platinum-resistant ovarian cancer underwent four-day 3-AP (96 mg/m(2), day one to four) and cisplatin (25 mg/m(2), day two and three) infusions every 21 days until disease progression or adverse effects prohibited further therapy. Pre-therapy ovarian cancer tissues were analyzed by immunohistochemistry for RNR subunit expression as an indicator of cisplatin plus 3-AP treatment response.

Results: 3-AP preceding cisplatin exposure in platinum-resistant ovarian cancer cells was not as effective as sequencing cisplatin plus 3-AP together in cell survival assays. Platinum-mediated DNA damage (i.e., γH2AX foci) resolved quickly after cisplatin-alone or 3-AP preceding cisplatin exposure, but persisted after a cisplatin plus 3-AP sequence. On trial, 25 four-day overlapping 3-AP and cisplatin cycles were administered to six women (median 4.2 cycles per patient). 3-AP-related methemoglobinemia (range seven to 10%) occurred in two (33%) of six women, halting trial accrual.

Conclusions: When sequenced cisplatin plus 3-AP, RNR inhibition restored platinum-sensitivity in platinum-resistant ovarian cancers. 3-AP (96 mg/m(2)) infusions produced modest methemoglobinemia, the expected consequence of ribonucleotide reductase inhibitors disrupting collateral proteins containing iron.

Trial registry: ClinicalTrials.gov NCT00081276.

Show MeSH
Related in: MedlinePlus