No abstract

Silencing gene expression by siRNAs is rapidly becoming a powerful tool for the genetic analysis of mammalian cells. However, the rapid degradation of siRNA and the limited duration of its action call for an efficient delivery technology. Accordingly, we describe here that Atelocollagen complexed with siRNA is resistant to nucleases and is efficiently transduced into cells, thereby allowing long-term gene silencing. Site-specific in vivo administration of an anti-luciferase siRNA/Atelocollagen complex reduced luciferase expression in a xenografted tumor. Furthermore, Atelocollagen-mediated transfer of siRNA in vivo showed efficient inhibition of tumor growth in an orthotopic xenograft model of a human non-seminomatous germ cell tumor. Thus, for clinical applications of siRNA, an Atelocollagen-based non-viral delivery method could be a reliable approach to achieve maximal function of siRNA in vivo.

By a molecular genetic approach using polymorphic DNA markers that detect allelic deletion of specific chromosomal regions, we analyzed for possible loss of chromosomal heterozygosity in five different histological types of lung cancers obtained from 47 patients. In small-cell carcinomas, the incidence of allelic deletions at three different chromosomal loci was extremely high; loss of heterozygosity was detected on chromosomes 3p in 7 of 7 patients (100%), 13q in 10 of 11 patients (91%), and 17p in 5 of 5 patients (100%). The deletions at these loci in small-cell carcinomas were observed even in the tumors without any clinical evidence of metastasis. Furthermore, loss of heterozygosity on chromosomes 3p and 13q occurred prior to NMYC amplification and chromosome 1lp deletion. Loss ofheterozygosity on chromosome 3p was also detected with high frequency in adenocarcinomas [5 of 6 patients (83%)]. Heterozygosity of chromosomes 13q and 17p was lost in 10 of31 patients (32%) and in 3 of 12 patients (25%), respectively, of lung cancers other than small-cell carcinomas. These results indicate that recessive genetic changes involving sequences on chromosomes 3p, 13q, and 17p may play important roles in the genesis of small-cell carcinoma, and those on chromosome 3p may play an important role in the genesis of adenocarcinoma.

No abstract

Loss of heterozygosity on chromosome 16 is a common genetic alteration in human hepatocellular carcinoma (HCC). To clarify the pathogenetic significance of allele loss on chromosome 16, we performed restriction fragment length polymorphism analysis of 70 surgically resected tumors by using 15 polymorphic DNA markers for chromosome 16. Loss of heterozygosity on chromosome 16 was detected in 36 (52%) of 69 informative cases, and the common region of allele loss in these 36 tumors was located between the HP locus (16q22.1) and the CTRB locus (16q22.3-q23.2). These losses occurred more frequently in HCCs ofpoor differentiation, of larger size, and with metastasis, whereas they were not detected in HCC at the earliest stage. In addition, these losses were not associated with presence or absence of hepatitis B virus DNA integration or hepatitis C virus infection. These results show that loss of heterozygosity on chromosome 16 is a late event occurring after hepatocarcinogenesis and strongly suggest that this phenomenon is involved in enhancement of tumor aggressiveness during progression of HCC.