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Figure 3 | BMC Cancer

Figure 3

From: A novel method, digital genome scanning detects KRAS gene amplification in gastric cancers: involvement of overexpressed wild-type KRAS in downstream signaling and cancer cell growth

Figure 3

Gene amplification of KRAS in gastric cancer cells. (a) Quantitative genomic PCR analysis of the KRAS locus at 12p12.1 in HSC45 cells. Discrete amplifications at 12p12.1 in two other gastric cancer cell lines were also detected (SH101P4 and MKN1). DNA copy number relative to normal diploid leukocyte DNA was plotted against chromosomal nucleotide position (in megabases). The positions of refseq genes in the corresponding regions are shown in the bottom map. The minimum amplification region common to all 3 gastric cancer cell lines is represented by the orange-colored bar. (b) Metaphase (left)- and interphase (right)-FISH analysis of the amplified KRAS locus in gastric cancer cell lines. The KRAS-specific probe is in yellow, and the control probe, specific for the long arm of chromosome 12, is in red. Tetraploidy in HSC45 and triploidy in SH101P4 and MKN1 cells were observed. (c) Quantitative real-time RT-PCR analysis of KRAS mRNA expression in gastric cancer cells with 12p12.1 amplification. Expression analysis of genes (KRAS, LRMP, CASC1 and LYRM5) located within the minimal amplicon, and BCAT1, which flanks the minimal amplicon, was performed using real-time RT-PCR. Expression levels were normalized to GAPDH mRNA, and are depicted as a color gradient, relative to normal stomach. The gene amplification and mutation (codon 12 or 13) status of KRAS for each sample is summarized in the right two columns. Filled circles indicate the presence of amplification or mutation of KRAS, and open circles indicate no amplification or no mutation of KRAS.

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