Figure 5. Lung gene expression profiles during urethane-induced tumorigenesis.

(A) Urethane effects on gene expression during lung tumorigenesis were compared by biological function and disorder categories of genes significantly changed in pre-/early-neoplastic stage at 12 wk (top), in uninvolved tissues (UN) at 22 wk (middle), and in tumors at 22 wk (bottom) using Ingenuity Pathway Analysis (IPA). Top-ranked categories are depicted against -log(p) determined by IPA. (B) Among the lung gene transcripts significantly (p<0.05) changed in uninvolved (UN, n = 1564) and tumor (n = 8683) tissues compared to saline-treated lung tissues, Venn diagram analysis identified genes changed in either tissue or in common at 22 wk after the initial urethane treatment (top). Expression profiles of all tumor genes (n = 8683, 22 wk UT-Tum) are depicted in pre-/early neoplastic microenvironment (12 wk) and in UN tissues of tumor-bearing lungs at 22 wk (bottom). Color bar indicates expression intensity of individual transcripts normalized to their time-matched saline control levels expressed in yellow (yellow to blue, down-regulation; yellow to red, up-regulation). Y axis = log₂ (normalized average intensity), Sal = saline-treated whole lung, UT = urethane-treated (whole lung for 12 wk, UN or Tum for 22 wk), UN = uninvolved tissue, Tum = tumor tissue.