Genome scanning at a 1-Mb resolution was undertaken in 29 lung cancer cell lines to clarify the distribution of homozygous (i.e., both allele) deletions along lung cancer genomes, using a high-resolution single nucleotide polymorphism array. Eighteen regions, including two known tumor suppressor loci, CDKN2A at 9p21 and FHIT at 3p14, were found homozygously deleted. Frequencies of deletions at the 18 regions were evaluated by genomic polymerase chain reaction in 78 lung cancer cell lines. Seven regions, 2q24, 3p14, 5q11, 9p21, 9p23, 11q14, and 21q21, were homozygously deleted in two or more cell lines. The CDKN2A locus at 9p21 was most frequently deleted (20/78, 26%), and the deletions were detected exclusively in non-small-cell lung carcinomas (NSCLCs). The PTPRD (protein tyrosine phosphatase receptor type D) locus at 9p23 was the second-most frequently deleted (8/78, 10%), and the deletions were detected in both small-cell lung carcinomas (SCLC) and NSCLC. In addition, the 9p24 region was deleted in a NSCLC. In total, 24 (31%) cell lines carried at least one deletion on chromosome arm 9p, while deletions on the remaining chromosome arms were observed at most in four (5%) cell lines. Deletions at 9p24, 9p23, and 9p21 were not contiguous with one another, and preferential co-occurrence or mutual exclusiveness for the deletions at these three loci was not observed. Thus, it was indicated that 9p is the most frequent target of homozygous deletions in lung cancer, suggesting that the arm contains multiple lung tumor suppressor genes and/or genomic features fragile during lung carcinogenesis.

A novel human chondroitin 6-O-sulfotransferase, designated C6ST-2, was identified by BLAST analysis of expressed sequence tag using the sequence of a previously described human chondroitin 6-O-sulfotransferase (C6ST-1) as a probe. The new cDNA sequence revealed an open reading frame coding for a protein of 486 amino acids with a type II transmembrane protein topology. The amino acid sequence displayed 24% identity to the human C6ST-1, and the highest sequence identity was found in the COOH-terminal catalytic domain. The expression of a soluble recombinant form of the protein in COS-1 cells produced an active sulfotransferase with marked specificity for polymer chondroitin. In contrast, keratan sulfate and oligosaccharides containing the Gal␤1-4GlcNAc sequence, which are good acceptor substrates for the C6ST-1, hardly served as acceptors. The identification of the reaction product indicated that the enzyme is a novel chondroitin 6-Osulfotransferase (C6ST-2) that mainly transfers sulfate to N-acetylgalactosamine. The coding region of C6ST-2 was contained in a single exon and localized to chromosome Xp11. Northern blot analysis of human brain poly(A) ؉ RNA revealed a single transcript of 2.4 kilobase pairs. Reverse transcription-polymerase chain reaction analysis showed that C6ST-2 is developmentally regulated in various tissues with expression persisting through adulthood in the spleen. Thus, we demonstrated the redundancy in chondroitin 6-O-sulfotransferases capable of forming chondroitin 6-sulfate, which is important for understanding the mechanisms leading to specific changes in the sulfation profile of chondroitin sulfate chains in various tissues during development and malignant transformation.

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The lactate dehydrogenases (LDHs) in hagfish have been estimated to be the prototype of those in higher vertebrates. The effects of high hydrostatic pressure from 0.1 to 100 MPa on LDH activities from three hagfishes were examined. The LDH activities of Eptatretus burgeri, living at 45–60 m, were completely lost at 5 MPa. In contrast, LDH-A and -B in Eptatretus okinoseanus maintained 70% of their activities even at 100 MPa. These results show that the deeper the habitat, the higher the tolerance to pressure. To elucidate the molecular mechanisms for adaptation to high pressure, we compared the amino acid sequences and three-dimensional structures of LDHs in these hagfish. There were differences in six amino acids (6, 10, 20, 156, 269, and 341). These amino acidresidues are likely to contribute to the stability of the E. okinoseanus LDH under high-pressure conditions. The amino acids responsible for the pressure tolerance of hagfish are the same in both human and hagfish LDHs, and one substitution that occurred as an adaptation during evolution is coincident with that observed in a human disease. Mutation of these amino acids can cause anomalies that may be implicated in the development of human diseases.