The entire DNA sequence of chromosome III of the yeast Saccharomyces cerevisiae has been determined. This is the first complete sequence analysis of an entire chromosome from any organism. The 315-kilobase sequence reveals 182 open reading frames for proteins longer than 100 amino acids, of which 37 correspond to known genes and 29 more show some similarity to sequences in databases. Of 55 new open reading frames analysed by gene disruption, three are essential genes; of 42 non-essential genes that were tested, 14 show some discernible effect on phenotype and the remaining 28 have no overt function.

Oncolytic virus therapy is perhaps the next major breakthrough in cancer treatment following the success in immunotherapy using immune checkpoint inhibitors. Oncolytic viruses are defined as genetically engineered or naturally occurring viruses that selectively replicate in and kill cancer cells without harming the normal tissues. T‐Vec (talimogene laherparepvec), a second‐generation oncolytic herpes simplex virus type 1 (HSV‐1) armed with GM‐CSF, was recently approved as the first oncolytic virus drug in the USA and Europe. The phase III trial proved that local intralesional injections with T‐Vec in advanced malignant melanoma patients can not only suppress the growth of injected tumors but also act systemically and prolong overall survival. Other oncolytic viruses that are closing in on drug approval in North America and Europe include vaccinia virus JX‐594 (pexastimogene devacirepvec) for hepatocellular carcinoma, GM‐CSF‐expressing adenovirus CG0070 for bladder cancer, and Reolysin (pelareorep), a wild‐type variant of reovirus, for head and neck cancer. In Japan, a phase II clinical trial of G47∆, a third‐generation oncolytic HSV‐1, is ongoing in glioblastoma patients. G47∆ was recently designated as a “Sakigake” breakthrough therapy drug in Japan. This new system by the Japanese government should provide G47∆ with priority reviews and a fast‐track drug approval by the regulatory authorities. Whereas numerous oncolytic viruses have been subjected to clinical trials, the common feature that is expected to play a major role in prolonging the survival of cancer patients is an induction of specific antitumor immunity in the course of tumor‐specific viral replication. It appears that it will not be long before oncolytic virus therapy becomes a standard therapeutic option for all cancer patients.

The existence of tumor-suppressor genes was originally demonstrated by functional complementation through whole-cell and microcell fusion. Transfer of chromosome 11 into a human non-small-cell lung cancer (NSCLC) cell line, A549, suppresses tumorigenicity. Loss of heterozygosity (LOH) on the long arm of chromosome 11 has been reported in NSCLC and other cancers. Several independent studies indicate that multiple tumor-suppressor genes are found in this region, including the gene PPP2R1B at 11q23-24 (ref. 7). Linkage studies of NSCLC are precluded because no hereditary forms are known. We previously identified a region of 700 kb on 11q23.2 that completely suppresses tumorigenicity of A549 human NSCLC cells. Most of this tumor-suppressor activity localizes to a 100-kb segment by functional complementation. Here we report that this region contains a single confirmed gene, TSLC1, whose expression is reduced or absent in A549 and several other NSCLC, hepatocellular carcinoma (HCC) and pancreatic cancer (PaC) cell lines. TSLC1 expression or suppression is correlated with promoter methylation state in these cell lines. Restoration of TSLC1 expression to normal or higher levels suppresses tumor formation by A549 cells in nude mice. Only 2 inactivating mutations of TSLC1 were discovered in 161 tumors and tumor cell lines, both among the 20 primary tumors with LOH for 11q23.2. Promoter methylation was observed in 15 of the other 18 primary NSCLC, HCC and PaC tumors with LOH for 11q23.2. Thus, attenuation of TSLC1 expression occurred in 85% of primary tumors with LOH. Hypermethylation of the TSLC1 promoter would seem to represent the 'second hit' in NSCLC with LOH.

The complete DNA sequence of the yeast Saccharomyces cerevisiae chromosome XI has been determined. In addition to a compact arrangement of potential protein coding sequences, the 666,448-base-pair sequence has revealed general chromosome patterns; in particular, alternating regional variations in average base composition correlate with variations in local gene density along the chromosome. Significant discrepancies with the previously published genetic map demonstrate the need for using independent physical mapping criteria.

We have recently identified a tumor suppressor gene TSLC1 on chromosome 11q23.2 by functional complementation of a human lung cancer cell line, A549, through suppression of tumorigenicity in nude mice (1). Furthermore, we have demonstrated the two-hit inactivation of TSLC1 in primary non-small cell lung cancer, hepatocellular carcinoma, and pancreatic cancer, implying its involvement in various human cancers (1). TSLC1 encodes a member of the immunoglobulin superfamily proteins comprising three Ig-like C2-type domains, a single hydrophobic membrane-spanning ␣-helix, and a cytoplasmic domain containing a putative signaling motif (1). From the significant homology of its extracellular domain with those of NCAM1 and NCAM2, 1 we have inferred that TSLC1 is capable of mediating cell-cell interaction.Cell adhesion molecules generally fall into four major classes: the cadherins, the integrins, the selectins, and the Ig superfamily. Among them, Ig superfamily cell adhesion molecules (IgCAMs) are the largest, numbering well over 100 members in vertebrates (2). These well-characterized molecules include NCAMs (3), L1 family CAMs (4), and nectins (5-8). Whereas cadherins and integrins require divalent cations such as Ca 2ϩ or Mg 2ϩ for their adhesive activities (9), IgCAMs are usually Ca 2ϩ -or Mg 2ϩ -independent (10). Moreover, most IgCAMs have preferences for homophilic and/or heterophilic interactions (10). In combination with these interactions, IgCAMs promote a variety of cell-cell associations through cis interaction within the plane of the membranes and/or trans interaction across the membranes (2, 11). For instance, the heterophilic cis interaction between L1 and NCAM appears to enhance the homophilic trans-binding activity of L1 (12, 13). Nectins form cis-homodimers that undergo homophilic and heterophilic trans interactions with each other to mediate cell-cell adhesion (6,11).In this study, the biochemical properties and subcellular localization of TSLC1 were investigated in the cells expressing TSLC1 tagged with GFP or endogenous TSLC1. We report the physiological properties of TSLC1 along with several lines of evidence that TSLC1 is a single transmembrane glycoprotein involved in cell-cell aggregation through homophilic trans interaction.

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A gene for high-affinity glucose transport, HGT1, has been isolated from the lactose-assimilating yeast Kluyveromyces lactis. Disruption strains showed much-reduced uptake of glucose at low concentrations and growth was particularly affected in low-glucose medium. The HGT1 nucleotide sequence implies that it encodes a typical transmembrane protein with 12 hydrophobic domains and with 26 to 31% amino acid identity with the Hxtp family of glucose transport elements in Saccharomyces cerevisiae. Expression is constitutive (in contrast to RAG1, the major gene for low-affinity glucose uptake in K. lactis) and is controlled by several genes also known to affect expression of RAG1. These include RAG5 (which codes for the single hexokinase of K. lactis), which is required for HGT1 transcription, and RAG4, which has a negative effect. The double mutant ⌬hgt1⌬rag1 showed further reduced glucose uptake but still grew quite well on 2% glucose and was not completely impaired even on 0.1% glucose.Eukaryotic and bacterial sugar transport proteins are related in protein sequence and cellular topology, forming the sugar permease superfamily (1). Within this superfamily of proteins are found transporters that act either by facilitated diffusion or by proton symport mechanisms (17

The R4GI gene of Kluyveromyces lactis encodes a low-affinity glucose/fructose transporter. Its transcription is induced by glucose, fructose, and several other sugars. The RAG4, RAGS, and RAG8 genes are trans-acting genes controlling the expression of the RAG) gene. We report here the characterization of one of these genes, RAG5. The nucleotide sequence of the cloned RAGS gene indicated that it encodes a protein that is homologous to hexokinases of Saccharomyces cerevisiae. ragS mutants showed no detectable hexokinase or glucokinase activity, suggesting that the sugar kinase activity encoded by this gene is the only hexokinase in K. lactis. Both high-and low-affinity transport systems of glucose were affected in ragS mutants. The defect of the low-affinity component was found to be due to a block of transcription of the RAG) gene by the hexokinase mutation. In vivo complementation of the rag5 mutation by the K2 gene of S. cerevisiae and complementation of hxikl hxk2 mutations of S. cerevisiae by the RAGS gene showed that RAGS and HXK2 were equivalent for sugar-phosphorylating activity but that RA4GS could not restore glucose repression in the S. cerevisiae hexokinase mutants.