To investigate genes involved in pulmonary carcinogenesis and those related to sensitivity of nonsmall cell lung cancers (NSCLCs) to therapeutic drugs, we performed cDNA microarray analysis of 37 NSCLCs after lasercapture microdissection of cancer cells from primary tumors. A clustering algorithm applied to the expression data easily distinguished two major histological types of non-small cell lung cancer, adenocarcinoma and squamous cell carcinoma. Subsequent analysis of the 18 adenocarcinomas identified 40 genes whose expression levels could separate cases with lymph-node metastasis from those without metastasis. In addition, we compared the expression data with measurements of the sensitivity of surgically dissected NSCLC specimens to six anti-cancer drugs (docetaxel, paclitaxel, irinotecan, cisplatin, gemcitabine, and vinorelbine), as measured by the CD-DST (collagen gel droplet embedded culture-drug sensitivity test) method. We found significant associations between expression levels of dozens of genes and chemosensitivity of NSCLCs. Our results provide valuable information for eventually identifying predictive markers and novel therapeutic target molecules for this type of cancer.

Cell-cycle checkpoints controlling the orderly progression through mitosis are frequently disrupted in human cancers. One such checkpoint, entry into metaphase, is regulated by the CHFR gene encoding a protein possessing forkhead-associated and RING finger domains as well as ubiquitin-ligase activity. Although defects in this checkpoint have been described, the molecular basis and prevalence of CHFR inactivation in human tumors are still not fully understood. To address this question, we analyzed the pattern of CHFR expression in a number of human cancer cell lines and primary tumors. We found CpG methylation-dependent silencing of CHFR expression in 45% of cancer cell lines, 40% of primary colorectal cancers, 53% of colorectal adenomas, and 30% of primary head and neck cancers. Expression of CHFR was precisely correlated with both CpG methylation and deacetylation of histones H3 and H4 in the CpG-rich regulatory region. Moreover, CpG methylation and thus silencing of CHFR depended on the activities of two DNA methyltransferases, DNMT1 and DNMT3b, as their genetic inactivation restored CHFR expression. Finally, cells with CHFR methylation had an intrinsically high mitotic index when treated with microtubule inhibitor. This means that cells in which CHFR was epigenetically inactivated constitute loss-of-function alleles for mitotic checkpoint control. Taken together, these findings shed light on a pathway by which mitotic checkpoint is bypassed in cancer cells and suggest that inactivation of checkpoint genes is much more widespread than previously suspected.DNA methylation ͉ DNA methyltransferase ͉ mitotic checkpoint ͉ histone deacetylation

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