1. Somatic mutations in mitochondrial DNA do not associate with nuclear microsatellite instability in gastrointestinal cancer 
Simó Schwartz, M.D., Ph.D.*,†, Manuel Perucho, Ph.D.* 
Gastroenterology 
Volume 119, Issue 6, Pages (December 2000)
DOI: /S (00)
Copyright © 2000 American Gastroenterological Association Terms and Conditions

2. Fig. 1
Mutations in mtDNA were analyzed in a panel of colon and stomach tumors. The origin of these samples has been described previously.11,12 The panel included 40 colon and 28 stomach tumors with enhanced MSI and 63 colon tumors and 67 stomach tumors without. The characterization of the MSI status of these tumors was done using 2 mononucleotide repeats and 1 dinucleotide repeat, as described previously.11,12 The polycytidine repeat (C)8 within the mtDNA transcription control region (nucleotides 299–315) was analyzed from matched normal (N) and tumor (T) tissues. The pairs of samples from the same patients are indicated by the lines at top, always the normal at left and tumor at right. The corresponding nucleotide sequence (nucleotides 261–462 according to GenBank mitochondrial sequence ID g ) was amplified by polymerase chain reaction (PCR) with Taq DNA polymerase and the specific primers 5'-CCA CTT TCC ACA CAG ACA T-3' and 5'-GGA GGG GAA AAT AAT GTG TTA G-3'. PCR products were analyzed on a 6% denaturing polyacrylamide gel and autoradiography. This method allows the detection within the (C)8 tract of insertions or deletions of 1 or a few base pairs (see arrowheads pointing up or down in A). In some cases the normal tissues exhibited heterogeneity in the mitochondrial DNA population (*). (B). No significant differences (χ2 test) in mutation frequency were found between colon or stomach tumors with and without MSI neither between colon and stomach tumors according to their MMP status (C). mtDNA variants from normal tissues and tu-mors were confirmed by cloning and sequencing the PCR products.
Gastroenterology  , DOI: ( /S (00) )
Copyright © 2000 American Gastroenterological Association Terms and Conditions