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Thiothymidine combined with UVA as a potential novel therapy for bladder cancer.

Pridgeon SW, Heer R, Taylor GA, Newell DR, O'Toole K, Robinson M, Xu YZ, Karran P, Boddy AV - Br. J. Cancer (2011)

Bottom Line: Addition of raltitrexed (Astra Zeneca, Alderley Edge, Cheshire, UK) increased the incorporation of S(4)TdR into DNA (up to 20-fold at IC(5)) and further sensitised cells to UVA.Cytotoxic effect was associated with crosslinking of DNA, at least partially to protein.Further work is necessary to optimise the delivery of the two components.

View Article: PubMed Central - PubMed

Affiliation: Northern Institute for Cancer Research, Medical School, Newcastle University, Newcastle NE2 4HH, UK.

ABSTRACT

Background: Thiothymidine (S(4)TdR) can be incorporated into DNA and sensitise cells to DNA damage and cell death following exposure to UVA light. Studies were performed to determine if the combination of S(4)TdR and UVA could be an effective treatment for bladder cancer.

Methods: Uptake and incorporation of S(4)TdR was determined in rat and human bladder tumour cell lines. Measures of DNA crosslinking and apoptosis were also performed. In vivo activity of the combination of S(4)TdR and UVA was investigated in an orthotopic model of bladder cancer in rats.

Results: Thiothymidine (200 μM) replaced up to 0.63% of thymidine in rat and tumour bladder cancer cells. The combination of S(4)TdR (10-200 μM) and UVA (1-5 kJ m(-2)) caused apoptosis and cell death at doses that were not toxic alone. Addition of raltitrexed (Astra Zeneca, Alderley Edge, Cheshire, UK) increased the incorporation of S(4)TdR into DNA (up to 20-fold at IC(5)) and further sensitised cells to UVA. Cytotoxic effect was associated with crosslinking of DNA, at least partially to protein. Intravenous administration of S(4)TdR, in combination with UVA delivered directly to the bladder, resulted in an antitumour effect in three of five animals treated.

Conclusion: These data indicate that the combination of S(4)TdR and UVA has potential as a treatment for bladder cancer, and give some insight into the mechanism of action. Further work is necessary to optimise the delivery of the two components.

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Related in: MedlinePlus

Typical comet images from MYU-3L cells treated with S4TdR and UVA. Thiothymidine treatment was for two cell-doubling times at 200 μ and UVA exposure was at 10 kJ m−2. Irradiated cells were exposed to 20 Gy X-irradiation. (A) Unirradiated control; (B) Unirradiated S4TdR control; (C) Unirradiated UVA control; (D) Unirradiated S4TdR and UVA; (E) Irradiated S4TdR control; (F) Irradiated UVA control; (G) Irradiated control; (H) Irradiated S4TdR+UVA.
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fig4: Typical comet images from MYU-3L cells treated with S4TdR and UVA. Thiothymidine treatment was for two cell-doubling times at 200 μ and UVA exposure was at 10 kJ m−2. Irradiated cells were exposed to 20 Gy X-irradiation. (A) Unirradiated control; (B) Unirradiated S4TdR control; (C) Unirradiated UVA control; (D) Unirradiated S4TdR and UVA; (E) Irradiated S4TdR control; (F) Irradiated UVA control; (G) Irradiated control; (H) Irradiated S4TdR+UVA.

Mentions: The DNA lesions induced by S4TdR/UVA treatment were assessed using the comet assay. The crosslinking of DNA S4TdR was measured as a reduction in comet tail moments in X-irradiated cells. Typical comet images are shown in Figure 4. An X-ray dose of 20 Gy induced comets in the nondrug-treated control cells (Figures 4A and G). The length of the comet tail was significantly shorter in X-irradiated cells that had previously been treated with 200 μ S4TdR and 10 kJ m−2 UVA. The mean reduction in Olive tail moment by S4TdR/UVA was 55 and 51% for MYU-3L and AY27 cells, respectively, in three independent experiments. As expected, there was no visible DNA migration in samples that were not X-irradiated. To examine whether formation of DNA–Protein crosslinks by S4TdR /UVA contributed to the reduced DNA migration, slides were treated with proteinase K before electrophoresis. Protease digestion caused a 24% increase in tail moment compared with untreated slides (data not shown).


Thiothymidine combined with UVA as a potential novel therapy for bladder cancer.

Pridgeon SW, Heer R, Taylor GA, Newell DR, O'Toole K, Robinson M, Xu YZ, Karran P, Boddy AV - Br. J. Cancer (2011)

Typical comet images from MYU-3L cells treated with S4TdR and UVA. Thiothymidine treatment was for two cell-doubling times at 200 μ and UVA exposure was at 10 kJ m−2. Irradiated cells were exposed to 20 Gy X-irradiation. (A) Unirradiated control; (B) Unirradiated S4TdR control; (C) Unirradiated UVA control; (D) Unirradiated S4TdR and UVA; (E) Irradiated S4TdR control; (F) Irradiated UVA control; (G) Irradiated control; (H) Irradiated S4TdR+UVA.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
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fig4: Typical comet images from MYU-3L cells treated with S4TdR and UVA. Thiothymidine treatment was for two cell-doubling times at 200 μ and UVA exposure was at 10 kJ m−2. Irradiated cells were exposed to 20 Gy X-irradiation. (A) Unirradiated control; (B) Unirradiated S4TdR control; (C) Unirradiated UVA control; (D) Unirradiated S4TdR and UVA; (E) Irradiated S4TdR control; (F) Irradiated UVA control; (G) Irradiated control; (H) Irradiated S4TdR+UVA.
Mentions: The DNA lesions induced by S4TdR/UVA treatment were assessed using the comet assay. The crosslinking of DNA S4TdR was measured as a reduction in comet tail moments in X-irradiated cells. Typical comet images are shown in Figure 4. An X-ray dose of 20 Gy induced comets in the nondrug-treated control cells (Figures 4A and G). The length of the comet tail was significantly shorter in X-irradiated cells that had previously been treated with 200 μ S4TdR and 10 kJ m−2 UVA. The mean reduction in Olive tail moment by S4TdR/UVA was 55 and 51% for MYU-3L and AY27 cells, respectively, in three independent experiments. As expected, there was no visible DNA migration in samples that were not X-irradiated. To examine whether formation of DNA–Protein crosslinks by S4TdR /UVA contributed to the reduced DNA migration, slides were treated with proteinase K before electrophoresis. Protease digestion caused a 24% increase in tail moment compared with untreated slides (data not shown).

Bottom Line: Addition of raltitrexed (Astra Zeneca, Alderley Edge, Cheshire, UK) increased the incorporation of S(4)TdR into DNA (up to 20-fold at IC(5)) and further sensitised cells to UVA.Cytotoxic effect was associated with crosslinking of DNA, at least partially to protein.Further work is necessary to optimise the delivery of the two components.

View Article: PubMed Central - PubMed

Affiliation: Northern Institute for Cancer Research, Medical School, Newcastle University, Newcastle NE2 4HH, UK.

ABSTRACT

Background: Thiothymidine (S(4)TdR) can be incorporated into DNA and sensitise cells to DNA damage and cell death following exposure to UVA light. Studies were performed to determine if the combination of S(4)TdR and UVA could be an effective treatment for bladder cancer.

Methods: Uptake and incorporation of S(4)TdR was determined in rat and human bladder tumour cell lines. Measures of DNA crosslinking and apoptosis were also performed. In vivo activity of the combination of S(4)TdR and UVA was investigated in an orthotopic model of bladder cancer in rats.

Results: Thiothymidine (200 μM) replaced up to 0.63% of thymidine in rat and tumour bladder cancer cells. The combination of S(4)TdR (10-200 μM) and UVA (1-5 kJ m(-2)) caused apoptosis and cell death at doses that were not toxic alone. Addition of raltitrexed (Astra Zeneca, Alderley Edge, Cheshire, UK) increased the incorporation of S(4)TdR into DNA (up to 20-fold at IC(5)) and further sensitised cells to UVA. Cytotoxic effect was associated with crosslinking of DNA, at least partially to protein. Intravenous administration of S(4)TdR, in combination with UVA delivered directly to the bladder, resulted in an antitumour effect in three of five animals treated.

Conclusion: These data indicate that the combination of S(4)TdR and UVA has potential as a treatment for bladder cancer, and give some insight into the mechanism of action. Further work is necessary to optimise the delivery of the two components.

Show MeSH
Related in: MedlinePlus