Int J Hyperthermia. 2009 Feb;25(1):41-6.
- Borkamo ED, Dahl O, Bruland O, Fluge Ø.Section of Oncology, Institute of Medicine, University of Bergen, Bergen, Norway.
To analyze effects of hyperthermia on immune cells within tumors.
- MATERIALS AND METHODS: Subcutaneously implanted rat gliomas were
treated with water-bath hyperthermia for one hour at day zero (HT)
(intratumoral temperature of 43 degrees C), low-dose metronomic
cyclophosphamide (CTX) 35 mg/kg three times a week for two weeks, both
HT and CTX (CTX-HT(0)), or saline. Tumors harvested at day 1, 7, 14 and
21 were analyzed for changes in gene expression by microarrays,
focusing on genes expressed in immune cells. Microarray analyses and
real-time RT-PCR were previously performed on tumors harvested day zero
at 0, 45, 90 and 180 minutes after end of treatment. Gene expression
kinetics of selected genes were analyzed in all tumors by quantitative
real-time RT-PCR (qPCR) to validate the results of the microarrays.
- RESULTS: Previous microarray analyses have indicated a suppression of
gene expression in immune cells within tumors by hyperthermia the first
three hours after treatment. qPCR analyses of CD14, CD36, Klrd1 (CD94),
Tlr2 and Lrp1 confirmed these results. Global mRNA screen revealed no
hyperthermia-induced changes in gene expression of immune cells at day
1, 7, 14 and 21. qPCR analyses of CD14, CD36, Klrd1 (CD94), Tlr2 and
Lrp1 confirmed the results of the microarrays, i.e. none of these were
differentially expressed after the first day, with the exception of
Lrp1 which displayed elevated mRNA levels.
- CONCLUSION: The suppression
in gene expression of a range of immune cells within tumors treated
with hyperthermia at 43 degrees C is a transient phenomenon.