DIFFERENTIAL THERMO-RESISTANCE OF MULTICELLULAR TUMOR SPHEROIDS

Document Type: Regular Paper

Authors

1 Laboratory of Biophysics and Molecular Biology Institute of Biochemistry and Biophysics University of Tehran, Tehran, I.R. of Iran

2 Department of Medical Physics, University of Medical Science, Tehran, I. R. of Iran

Abstract

Many cell lines, when cultured under proper conditions, can form three dimensional
structures called multicellular spheroids. These spheroids resemble in vivo tumor models in several
aspects. Therefore, studying growth characteristics and behavior of spheroids is beneficial in
understanding the behavior of tumors under various experimental conditions. In this work, we have
studied the growth properties, along with the thermal characteristics of spheroids of DU 145 human
prostate carcinoma cell lines and compared the results to monolayer cultures of these cells. For this
purpose, the DU 145 cells were cultured either as monolayer or spheroids. At various times after
initiation of cultures, the growth properties of spheroids as a function of seeding cell number was
determined. To evaluate the thermal characteristics of spheroids, they were heated at various stages of
growth at 43 °C for various periods. The thermal response was judged by the survival fraction of colony
forming cells in spheroids or monolayer culture following heat treatment. The results showed spheroids
were more resistant to heat than monolayer cultures at all stages of development. However, the extent of
this thermal resistant was dependent on the age, and consequently, the size of the spheroid. The result
suggests that the differential thermal resistance of the spheroid cultures develop gradually during the
growth of spheroid cultures of DU 145 cell line.

Keywords