Clinicopathological characteristics of Epstein-Barr virus and microsatellite instability subtypes of early gastric neoplasms classified by the Japanese and the World Health Organization criteria.

Gastric cancer is a heterogenous disease with different phenotypes, genotypes, and clinical outcomes, including sensitivity to treatments and prognoses. Recent medical advances have enabled the classification of this heterogenous disease into several groups and the consequent analysis of their clinicopathological characteristics. Gastric cancer associated with Epstein-Barr virus (EBV) and microsatellite-unstable tumors are considered to be the two major subtypes as they are clearly defined by well-established methodologies, such as in situ hybridization and polymerase chain reaction-based analyses, respectively. However, discrepancies in the histological diagnosis of gastric neoplasms remain problematic, and international harmonization should be performed to improve our understanding of gastric carcinogenesis. We re-evaluated Japanese cases of early gastric cancer according to the current World Health Organization (WHO) criteria and classified them into genomic subtypes based on microsatellite instability (MSI) and EBV positivity to determine the initial genetic events in gastric carcinogenesis. A total of 113 Japanese early gastric cancers (including low- and high-grade dysplasias) treated with endoscopic resection over 5 years were archived in our hospital. A histological re-evaluation according to the WHO criteria revealed 54 adenocarcinomas, which were divided into 6 EBV-positive (11.1%), 7 MSI-high (MSI-H, 13.0%), and 41 microsatellite stable cases (75.9%). MSI-H adenocarcinoma was confirmed by an immunohistochemistry assay of mismatch repair proteins. Programmed death-ligand 1 immunostaining with two antibodies (E1L3N and SP263) was positive in tumor cells of one MSI-H adenocarcinoma case (1/7, 14.3%). The proportion of stained cells was higher with clone SP263 than with E1L3N. Histologically, EBV-positive carcinomas were poorly differentiated (83.8%), and MSI-H cancers were frequent in well to moderately differentiated adenocarcinoma (85.7%), indicating that the EBV-positive subtype presented with high-grade morphology even when an early lesion. Our study indicates that the WHO criteria are useful for subdividing Japanese early gastric cancers, and this subdivision may be useful for comparative analysis of precursor lesions and early carcinoma.

Complete sequencing and characterization of 21,243 full-length human cDNAs.

As a base for human transcriptome and functional genomics, we created the "full-length long Japan" (FLJ) collection of sequenced human cDNAs. We determined the entire sequence of 21,243 selected clones and found that 14,490 cDNAs (10,897 clusters) were unique to the FLJ collection. About half of them (5,416) seemed to be protein-coding. Of those, 1,999 clusters had not been predicted by computational methods. The distribution of GC content of nonpredicted cDNAs had a peak at approximately 58% compared with a peak at approximately 42%for predicted cDNAs. Thus, there seems to be a slight bias against GC-rich transcripts in current gene prediction procedures. The rest of the cDNAs unique to the FLJ collection (5,481) contained no obvious open reading frames (ORFs) and thus are candidate noncoding RNAs. About one-fourth of them (1,378) showed a clear pattern of splicing. The distribution of GC content of noncoding cDNAs was narrow and had a peak at approximately 42%, relatively low compared with that of protein-coding cDNAs.

Rice SPK, a calmodulin-like domain protein kinase, is required for storage product accumulation during seed development: phosphorylation of sucrose synthase is a possible factor.

Suc, an end product of photosynthesis, is metabolized by Suc synthase in sink organs as an initial step in the biosynthesis of storage products. Suc synthase activity is known to be regulated by reversible phosphorylation, but the details of this process are unclear at present. Rice SPK, a calcium-dependent protein kinase, is expressed uniquely in the endosperm of immature seed, and its involvement in the biosynthetic pathways of storage products was suggested. Antisense SPK transformants lacked the ability to accumulate storage products such as starch, but produced watery seed with a large amount of Suc instead, as the result of an inhibition of Suc degradation. Analysis of in vitro phosphorylation indicated that SPK phosphorylated specifically a Ser residue in Suc synthase that has been shown to be important for its activity in the degradation of Suc. This finding suggests that SPK is involved in the activation of Suc synthase. It appears that SPK is a Suc synthase kinase that may be important for supplying substrates for the biosynthesis of storage products.