Macrodissection versus microdissection of rectal carcinoma: minor influence of stroma cells to tumor cell gene expression profiles.
BACKGROUND
The molecular determinants of carcinogenesis, tumor progression and patient prognosis can be deduced from simultaneous comparison of thousands of genes by microarray analysis. However, the presence of stroma cells in surgically excised carcinoma tissues might obscure the tumor cell-specific gene expression profiles of these samples. To circumvent this complication, laser microdissection can be performed to separate tumor epithelium from the surrounding stroma and healthy tissue. In this report, we compared RNAs isolated from macrodissected, of which only surrounding healthy tissue had been removed, and microdissected rectal carcinoma samples by microarray analysis in order to determine the most reliable approach to detect the expression of tumor cell-derived genes by microarray analysis.


RESULTS
As microdissection yielded low tissue and RNA quantities, extra rounds of mRNA amplification were necessary to obtain sufficient RNA for microarray experiments. These second rounds of amplification influenced the gene expression profiles. Moreover, the presence of stroma cells in macrodissected samples had a minor contribution to the tumor cell gene expression profiles, which can be explained by the observation that more RNA is extracted from tumor epithelial cells than from stroma.


CONCLUSIONS
These data demonstrate that the more convenient procedure of macrodissection can be adequately used and yields reliable data regarding the identification of tumor cell-specific gene expression profiles.
de Bruin
Elza C
EC
Department of Clinical Oncology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands. E.C.de_Bruin@lumc.nl
van de Pas
Simone
S
Lips
Esther H
EH
van Eijk
Ronald
R
van der Zee
Minke M C
MM
Lombaerts
Marcel
M
van Wezel
Tom
T
Marijnen
Corrie A M
CA
van Krieken
J Han J M
JH
Medema
Jan Paul
JP
van de Velde
Cornelis J H
CJ
Eilers
Paul H C
PH
Peltenburg
Lucy T C
LT
D002277:Carcinoma / Q000378:metabolism; D016000:Cluster Analysis; D018076:DNA, Complementary / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D046228:Microarray Analysis; D042282:Microdissection / Q000379:methods*; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012334:RNA, Neoplasm / Q000378:metabolism; D012004:Rectal Neoplasms / Q000175:diagnosis* / Q000473:pathology*; D012984:Software; D017154:Stromal Cells / Q000378:metabolism
D018076:DNA, Complementary; D012333:RNA, Messenger; D012334:RNA, Neoplasm; D012313:RNA