The hybridized FDA was scanned with an Agilent dual-laser DNA microarray scanner G2565AA. Feature extraction and data normalization were conducted with Agilent Feature Extraction software. Relative

expression levels were measured by normalizing the signal intensities of Cy5 to those of Cy3. The mean of four replicate samples was used for each experiment (Fig. 1). Data were expressed as relative values against a house-keeping gene, glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Figure 1 Focused DNA array containing quadruplicate sets of oligonucleotide array sequences for 133 genes. High reproducibility of gene expression is confirmed in corresponding spots of the quadruplicate. Statistical analysis High mRNA expression was defined as above the average value of the 35 RNA samples. The relationship between mRNA expression and GEM efficacy Sepantronium purchase was examined by chi-squared test (Fisher’s exact test). ICG-001 chemical structure Survival data were estimated by the Kaplan-Meier method and were examined by log-rank test. Results Clinical outcome Five of 35 patients who completed two courses of GEM monotherapy showed PR, SD was seen in 19 patients, and progressive disease was seen in 11 patients. Among the 19 SD patients, pretreatment values for tumor markers in two patients were normal. Abnormal levels of tumor markers in seven of 17 SD-patients decreased by 50% or more as compared to pretreatment

values. When GEM efficacy was defined as PR or SD with a 50% or more decrease in tumor markers compared to baseline, 12 patients were classified into the effective group (Table 1). There was a significant difference between the survival periods of the effective and the non-effective groups (Median survival time, 16.6 months vs. 7.8 months, respectively; P = 0.0017) (Fig. 2). Figure 2 Probability of survival for patients with unresectable pancreatic ductal cancer stratified by gemcitabine efficacy. Open circles, GEM-effective group. Closed circles, GEM-non-effective group. There is a significant difference between survival in the two groups. RNA quantity

and quality Mean ± SD amount of total RNA from 35 tumors was 0.7 ± 0.7 μg (range, 0.1 – 3.0 μg). All 35 RNA samples were of sufficient quality (Fig. Fossariinae 3). Figure 3 Representative electropherogram of total RNA extracted from pancreatic cancer obtained by endoscopic ultrasound-guided fine-needle aspiration biopsy. The ratio of 28S to 18S of ribosomal RNA indicates good quality of total RNA. GEM sensitivity-related gene expression and clinical GEM efficacy Gene expressions as relative values against GAPDH were as follows: hENT-1, 3.88 (mean), 2.77–6.41 (range); hENT-2, 4.04, 2.54–6.68; dCK, 3.90, 2.21–6.79; DCD, 4.61, 3.09–7.60; CDA, 2.71, 0.27–7.89; 5′-NT, 4.30, 1.35–7.23; RRM1, 2.02, 0.41–5.53; RRM2, 0.91, 0.18–3.34. Among GEM sensitivity-related genes, dCK mRNA expression alone predicted GEM efficacy (Table 2).