Temperature-sensitive (ts) mutations have been used as a genetic and molecular tool to study the functions of many gene products. Each ts mutant protein may contain a temperature-dependent intramolecular mechanism such as ts conformational change. To identify key ts structural elements controlling the protein function, we screened ts p53 mutants from a comprehensive mutation library consisting of 2,314 p53 missense mutations for their sequence-specific transactivity through p53-binding sequences in Saccharomyces cerevisiae. We isolated 142 ts p53 mutants, including 131 unreported ts mutants. were ts hot spots. Among the 142 mutants, 54 were examined further in human osteosarcoma Saos-2 cells, and it was confirmed that 89% of the mutants were also ts in mammalian cells. The ts mutants represented distinct ts transactivities for the p53 binding sequences and a distinct epitope expression pattern for conformation-specific anti-p53 antibodies. These results indicated that the intramolecular ␤-sheet in the core DNA-binding domain of p53 was a key structural element controlling the protein function and provided a clue for finding a molecular mechanism that enables the rescue of the mutant p53 function.p53 tumor suppressor is a 393-amino acid transcription factor that activates the transcription of a number of downstream genes through p53 binding to two copies of the specific consensus DNA sequence 5Ј-RRRC(A/T)(T/A)GYYY-3Ј (in which R is a purine nucleoside and Y is a pyrimidine nucleoside) in their regulatory regions (1). These molecular switches are activated by post-translational modifications, including phosphorylation, acetylation, and prolyl isomerization (2-5) of p53 in response to genotoxic or non-genotoxic stresses. The resulting biological effects are cell cycle arrest, apoptosis, DNA repair, and angiogenesis (6 -10). A growing number of p53 downstream genes have been isolated, and p53 has been structurally and functionally divided into three portions, namely the NH 2 -terminal portion containing the transactivation domain, the central core portion corresponding to the DNA-binding domain, and the COOH-terminal portion containing the oligomerization domain. The evolution of the DNA-binding domain is highly conserved in p53 orthologues (11) and also in the conserved human homologues p63 and p73 (12, 13).The structure of the DNA-binding domain (residues 94 -312) was resolved by x-ray crystallography (14). The domain consists of two ␣-helixes (H1 and H2) and 11 ␤-strands (S1, S2, S2Ј, and S3-S10) that were interconnected by loops (long L1-L3 loops and other short loops). Two anti-parallel ␤-sheets containing four (S1, S3, S5, and S8) and five (S4, S6, S7, S9, and S10) ␤-strands make up a large ␤-sandwich that serves as a scaffold for a loop-sheet-helix (LSH) motif (L1, S2, S2Ј, S10, and H2) and two large loops (L2 and L3). The loop-sheet-helix consists of two separate regions as follows: (i) the L1 loop (residues 113-123) and the S2-S2Ј ␤-hairpin (residues 124 -135) that correspond to evolutionary conserved regio...

Somatic mutations in the gene encoding the catalytic subunit of protein phosphatase 6 (Ppp6c) have been identified in malignant melanoma and are thought to function as a driver in B-raf- or N-ras-driven tumorigenesis. To assess the role of Ppp6c in carcinogenesis, we generated skin keratinocyte-specific Ppp6c conditional knockout mice and performed two-stage skin carcinogenesis analysis. Ppp6c deficiency induced papilloma formation with 7,12-dimethylbenz (a) anthracene (DMBA) only, and development of those papillomas was significantly accelerated compared with that seen following DMBA/TPA (12-O-tetradecanoylphorbol 13-acetate) treatment of wild-type mice. NF-κB activation either by tumor necrosis factor (TNF)-α or interleukin (IL)-1β was enhanced in Ppp6c-deficient keratinocytes. Overall, we conclude that Ppp6c deficiency predisposes mice to skin carcinogenesis initiated by DMBA. This is the first report showing that such deficiency promotes tumor formation in mice.

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The recommended doses of docetaxel and nedaplatin were 30 and 80 mg/m(2), respectively. This combination could be a potential second-line treatment for this target population.

We sequenced approximately 23 kb genomic regions containing all the coding exons and their franking introns of two breast cancer susceptibility genes, BRCA1 and BRCA2, of 55 individuals from 50 unrelated Japanese breast cancer families. We identified 55 single-nucleotide polymorphisms (SNPs) (21 in BRCA1 and 34 in BRCA2) containing nine pathogenic protein-truncating mutations (four in BRCA1and five in BRCA2 from ten patients). Among the remaining 46 SNPs, allele frequencies of 40 were examined in both the breast cancer patients and 28 healthy volunteers with no breast cancer family history by PCR-RFLP or by direct DNA sequencing. Twenty-eight SNPs were common and were also found in the healthy volunteers and/or a SNP database. The remaining 18 were rare (allele frequency <0.05) and were not found in the healthy volunteers and/or the database. The pathogenic significance of these coding SNPs (cSNPs) remains to be clarified. The SNP information from this study will be useful in the future genetic testing of both BRCA1 and BRCA2 genes in the Japanese population.

The gene responsible for Peutz-Jeghers syndrome (PJS), LKB1 (also called STK11) was mapped to chromosome 19p13.3 and was found to encode a putative serine/threonine protein kinase, LKB1. As only a limited number (approximately 100) of germline mutations of the gene have been reported, and because the protein function is still unclear, information about LKB1 mutations and their expression should be accumulated to understand the phenotype-genotype correlation of this disease. Here we report a patient with sporadic PJS with early-onset gastric cancer. We found a novel germline frameshift mutation (757-758insT) in the LKB1 gene and a marked reduction in LKB1 protein expression in the carcinoma cells, suggesting that the loss of LKB1 function may have led to the carcinogenesis of the gastric cancer.

Background This study aimed to analyze the determinants of patients’ choice between palliative chemotherapy and best supportive care (BSC) and to investigate how this choice affects overall survival (OS) and length of hospitalization according to Eastern Cooperative Oncology Group (ECOG) performance status (PS). Methods An oncologist explained the palliative chemotherapy and BSC options to 129 patients with incurable cancer during their first consultation. Data on the ECOG PS, treatment decision, OS, and the length of hospitalization were retrospectively collected over 4 years. Results Patients with an ECOG PS of 0–2 chose palliative chemotherapy more often than those with an ECOG PS of 3–4 ( P < 0.01). Patients with ≤70 years chose palliative chemotherapy more often than those with > 70 ( P < 0.05). And patients with gastric cancer and colon cancer chose palliative chemotherapy more often than those with CUP (carcinoma of unknown primary) ( P < 0.05, P < 0.05 respectively). Factors associated with a significantly poorer OS in an adjusted analysis included the ECOG PS and treatment decision (hazard ratios: 0.18 and 0.43; P < 0.001, P < 0.01 respectively). In patients with an ECOG PS of 0–2, palliative chemotherapy was not associated with a longer OS compared with BSC (median OS: 14.5 vs. 6.8 months, respectively; P = 0.144). In patients with an ECOG PS of 3–4, palliative chemotherapy resulted in a significant survival gain compared to with BSC (median OS: 3.8 vs. 1.4 months, respectively; P < 0.05). Strong positive correlations between OS and the length of hospitalization were observed in patients with an ECOG PS of 3–4 who underwent palliative chemotherapy ( r 2 = 0.683) and the length of hospitalization was approximately one-third of their OS. Conclusions The determinants for treatment choice were age, ECOG PS and type of cancer, not sex difference. Oncologists should explain to patients that OS and the length of hospitalization vary according to the ECOG PS when selecting between palliative chemotherapy and BSC. Electronic supplementary material The online version of this article (10.1186/s12904-019-0428-3) contains supplementary material, which is available to authorized users.

APC gene mutations play a role in the initiation step of colorectal carcinogenesis in both familial adenomatous polyposis (FAP) and non-FAP patients. Almost all of the APC mutations are nonsense or frameshift mutations, which truncate the APC protein and are thought to inactivate normal APC function. We show a novel method for detecting nonsense and frameshift APC gene mutations by using Saccharomyces cerevisiae. Polymerase chain reaction (PCR)-amplified APC fragments are cloned directly into yeast expression vectors in vivo, and the yeast expresses a hemagglutinin epitope (HA)-tagged APC peptide. When an APC fragment contains a nonsense or frameshift mutation, HA-tagged truncating APC peptide can be detected by Western blotting using an anti-HA antibody. We identified both germ-line and somatic APC mutations in patients with FAP and non-FAP colorectal tumors, respectively. This method, called the yeast-based protein truncation test (YPTT), is simple and fairly cheap, and it can be applied to any genes that are inactivated by protein truncating mutations.