Premium
Biological response of multicellular emt6 spheroids to exogenous lactate
Author(s) -
BourratFloeck B.,
Groebe K.,
MuellerKlieser W.
Publication year - 1991
Publication title -
international journal of cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.475
H-Index - 234
eISSN - 1097-0215
pISSN - 0020-7136
DOI - 10.1002/ijc.2910470528
Subject(s) - spheroid , respiration , oxygen , oxygen tension , metabolism , chemistry , limiting oxygen concentration , biology , lactate dehydrogenase , cellular respiration , biophysics , biochemistry , in vitro , enzyme , anatomy , organic chemistry
The influence of elevated lactate concentrations, as found in tumor microregions, on cellular growth, viability, and metabolic state was studied employing the multicellular spheroid model. Spheroids of EMT6/Ro cells were cultured at 37°C in 5% or 20% (v/v) oxygen, using stirred media with various concentrations of exogenous lactate ranging from 0.0 mM (standard conditions) to 20.0 mM. Elevated concentrations of exogenous lactate led to a considerable decrease of the maximum spheroid diameter at growth saturation, e.g. , for 20% O 2 from around 1700 μm to 700 μm in 0.0 and 20.0 mM lactate respectively. Histological investigations showed that the thickness of the viable cell rim was increased by elevated lactate concentrations in 20% O 2 , whereas this correlation was reversed in 5% O 2 . Cultivation of spheroids in increasing lactate concentrations was associated with a shift of metabolic pathways from net production to increased utilization of lactate in both 20% and 5% O 2 , as determined by standard enzymatic assays. Oxygen tension (PO 2 ) values measured with micro‐electrodes were less in spheroids cultured in high lactate (9.0 and 20.0 mM) than under standard conditions, irrespective of the external oxygen concentration. This finding reflected a substantial increase in the cellular O 2 consumption with elevated external lactate levels. At given lactate concentrations, respiration rates that were derived from measured PO 2 distributions by theoretical considerations were significantly lower in 5% O 2 than in 20% O 2 .