Abstract
Recombinant human interleukin-1α (rIL-1α), at concentrations that were not growth-inhibitory when given alone (100-10,000 U/ml), enhanced the growth inhibition resulting from a 72-h fluorouracil (FUra) exposure in HCT116 colon cancer cells. Median-effect analysis of clonogenic assays indicated that rIL- 1α, given 24 h prior to and following a 24-h exposure to FUra, increased lethality in a more than additive fashion. rIL-1α did not appear to significantly affect [3H]-FUra metabolism, total [3H]-FUra-RNA incorporation or RNA retention after drug removal, inhibition of thymidylate synthase, or thymidine triphosphate pool depletion. During continuous exposure to rIL-1α, transient stimulation of RNA and DNA synthesis was observed at 72 h, with a return to normal by 96 h. A 24-h exposure to 10 μM FUra altered the elution profile of newly synthesized DNA as monitored by pH step alkaline elution. An accumulation of lower-MW single-stranded DNA species was noted with FUra compared to control, accompanied by a significantly decreased proportion of DNA retained on the polycarbonate filter: 10% retained vs. 32% for control (P = 0.01). A 48-h exposure to rIL- 1α alone did not affect the elution profile of nascent DNA species, nor did it enhance the effects of FUra. Although FUra did not appreciably affect pulse [3H]-uridine incorporation into RNA for the initial 8-24 h of FUra exposure, progressive inhibition of net RNA synthesis was observed thereafter. FUra prevented the stimulatory effect of rIL-1α on RNA synthesis, and net RNA synthesis was significantly inhibited (by 64-79% after 72 and 96 h) with the combination compared to rIL-1α alone. Continuous exposure to 10 μM thymidine did not rescue cells from the lethality of FUra alone or the combination of FUra plus rIL-1α suggesting that depletion of deoxythymidine triphosphate as a consequence of thymidylate synthase inhibition was not the most important component of FUra toxicity. In contrast, 1 mM uridine provided partial protection against the toxicity of FUra alone or with rIL-1α. Although uridine did not affect FUra metabolism, it decreased FUra-RNA incorporation by 42-60%, presumably as a consequence of the 2-fold expansion of UTP pools. [125I]-rIL-1α binding was nonspecific; with a 24-h exposure, however, internalized [125I]-rIL-1α exceeded cell surface-bound material by 2-fold. Concurrent exposure to 10 μM FUra increased the binding and internalization of [125I]-rIL-1α at 37°C by 2.7-fold. While the precise mechanism of interaction between FUra and IL-1α is unclear, the data suggest that RNA-directed cytotoxicity by FUra is contributory.
Original language | English (US) |
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Pages (from-to) | 581-591 |
Number of pages | 11 |
Journal | Oncology Research |
Volume | 6 |
Issue number | 12 |
State | Published - Dec 1 1994 |
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Keywords
- colorectal carcinoma
- cytokine-drug interaction
- fluorouracil
- interleukin-1α
ASJC Scopus subject areas
- Oncology
- Cancer Research
Cite this
Enhanced cytotoxicity with interleukin-1α and 5-fluorouracil in HCT116 colon cancer cells. / Geoffroy, F. J.; Allegra, C. J.; Sinha, B.; Grem, J. L.
In: Oncology Research, Vol. 6, No. 12, 01.12.1994, p. 581-591.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Enhanced cytotoxicity with interleukin-1α and 5-fluorouracil in HCT116 colon cancer cells
AU - Geoffroy, F. J.
AU - Allegra, C. J.
AU - Sinha, B.
AU - Grem, J. L.
PY - 1994/12/1
Y1 - 1994/12/1
N2 - Recombinant human interleukin-1α (rIL-1α), at concentrations that were not growth-inhibitory when given alone (100-10,000 U/ml), enhanced the growth inhibition resulting from a 72-h fluorouracil (FUra) exposure in HCT116 colon cancer cells. Median-effect analysis of clonogenic assays indicated that rIL- 1α, given 24 h prior to and following a 24-h exposure to FUra, increased lethality in a more than additive fashion. rIL-1α did not appear to significantly affect [3H]-FUra metabolism, total [3H]-FUra-RNA incorporation or RNA retention after drug removal, inhibition of thymidylate synthase, or thymidine triphosphate pool depletion. During continuous exposure to rIL-1α, transient stimulation of RNA and DNA synthesis was observed at 72 h, with a return to normal by 96 h. A 24-h exposure to 10 μM FUra altered the elution profile of newly synthesized DNA as monitored by pH step alkaline elution. An accumulation of lower-MW single-stranded DNA species was noted with FUra compared to control, accompanied by a significantly decreased proportion of DNA retained on the polycarbonate filter: 10% retained vs. 32% for control (P = 0.01). A 48-h exposure to rIL- 1α alone did not affect the elution profile of nascent DNA species, nor did it enhance the effects of FUra. Although FUra did not appreciably affect pulse [3H]-uridine incorporation into RNA for the initial 8-24 h of FUra exposure, progressive inhibition of net RNA synthesis was observed thereafter. FUra prevented the stimulatory effect of rIL-1α on RNA synthesis, and net RNA synthesis was significantly inhibited (by 64-79% after 72 and 96 h) with the combination compared to rIL-1α alone. Continuous exposure to 10 μM thymidine did not rescue cells from the lethality of FUra alone or the combination of FUra plus rIL-1α suggesting that depletion of deoxythymidine triphosphate as a consequence of thymidylate synthase inhibition was not the most important component of FUra toxicity. In contrast, 1 mM uridine provided partial protection against the toxicity of FUra alone or with rIL-1α. Although uridine did not affect FUra metabolism, it decreased FUra-RNA incorporation by 42-60%, presumably as a consequence of the 2-fold expansion of UTP pools. [125I]-rIL-1α binding was nonspecific; with a 24-h exposure, however, internalized [125I]-rIL-1α exceeded cell surface-bound material by 2-fold. Concurrent exposure to 10 μM FUra increased the binding and internalization of [125I]-rIL-1α at 37°C by 2.7-fold. While the precise mechanism of interaction between FUra and IL-1α is unclear, the data suggest that RNA-directed cytotoxicity by FUra is contributory.
AB - Recombinant human interleukin-1α (rIL-1α), at concentrations that were not growth-inhibitory when given alone (100-10,000 U/ml), enhanced the growth inhibition resulting from a 72-h fluorouracil (FUra) exposure in HCT116 colon cancer cells. Median-effect analysis of clonogenic assays indicated that rIL- 1α, given 24 h prior to and following a 24-h exposure to FUra, increased lethality in a more than additive fashion. rIL-1α did not appear to significantly affect [3H]-FUra metabolism, total [3H]-FUra-RNA incorporation or RNA retention after drug removal, inhibition of thymidylate synthase, or thymidine triphosphate pool depletion. During continuous exposure to rIL-1α, transient stimulation of RNA and DNA synthesis was observed at 72 h, with a return to normal by 96 h. A 24-h exposure to 10 μM FUra altered the elution profile of newly synthesized DNA as monitored by pH step alkaline elution. An accumulation of lower-MW single-stranded DNA species was noted with FUra compared to control, accompanied by a significantly decreased proportion of DNA retained on the polycarbonate filter: 10% retained vs. 32% for control (P = 0.01). A 48-h exposure to rIL- 1α alone did not affect the elution profile of nascent DNA species, nor did it enhance the effects of FUra. Although FUra did not appreciably affect pulse [3H]-uridine incorporation into RNA for the initial 8-24 h of FUra exposure, progressive inhibition of net RNA synthesis was observed thereafter. FUra prevented the stimulatory effect of rIL-1α on RNA synthesis, and net RNA synthesis was significantly inhibited (by 64-79% after 72 and 96 h) with the combination compared to rIL-1α alone. Continuous exposure to 10 μM thymidine did not rescue cells from the lethality of FUra alone or the combination of FUra plus rIL-1α suggesting that depletion of deoxythymidine triphosphate as a consequence of thymidylate synthase inhibition was not the most important component of FUra toxicity. In contrast, 1 mM uridine provided partial protection against the toxicity of FUra alone or with rIL-1α. Although uridine did not affect FUra metabolism, it decreased FUra-RNA incorporation by 42-60%, presumably as a consequence of the 2-fold expansion of UTP pools. [125I]-rIL-1α binding was nonspecific; with a 24-h exposure, however, internalized [125I]-rIL-1α exceeded cell surface-bound material by 2-fold. Concurrent exposure to 10 μM FUra increased the binding and internalization of [125I]-rIL-1α at 37°C by 2.7-fold. While the precise mechanism of interaction between FUra and IL-1α is unclear, the data suggest that RNA-directed cytotoxicity by FUra is contributory.
KW - colorectal carcinoma
KW - cytokine-drug interaction
KW - fluorouracil
KW - interleukin-1α
UR - http://www.scopus.com/inward/record.url?scp=0028657658&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0028657658&partnerID=8YFLogxK
M3 - Article
C2 - 7787251
AN - SCOPUS:0028657658
VL - 6
SP - 581
EP - 591
JO - Oncology Research
JF - Oncology Research
SN - 0965-0407
IS - 12
ER -