Different impacts of TP53 mutations on cell cycle-related gene expression among cancer types.

Functional properties caused by TP53 mutations are involved in cancer development and progression. Although most of the mutations lose normal p53 functions, some of them, gain-of-function (GOF) mutations, exhibiting novel oncogenic functions. No reports have analyzed the impact of TP53 mutations on the gene expression profile of the p53 signaling pathway across cancer types. This study is a cross-cancer type analysis of the effects of TP53 mutations on gene expression. A hierarchical cluster analysis of the expression profile of the p53 signaling pathway classified 21 cancer types into two clusters (A1 and A2). Changes in the expression of cell cycle-related genes and MKI67 by TP53 mutations were greater in cluster A1 than in cluster A2. There was no distinct difference in the effects between GOF and non-GOF mutations on the gene expression profile of the p53 signaling pathway.

Altered gene expression due to aberrant DNA methylation correlates with responsiveness to anti-EGFR antibody treatment.

The cetuximab gene expression signature and DNA methylation status of colorectal cancer (CRC) are predictive of the therapeutic effects of anti-epidermal growth factor receptor (EGFR) antibody therapy. As DNA methylation is a means of regulating gene expression, it may play an important role in the expression of cetuximab signature genes. This study aims to determine the effects of aberrant DNA methylation on the regulation of cetuximab signature gene expression. Comprehensive DNA methylation and gene expression data were retrieved from CRC patients in three tumor tissue (TT) cohorts and three normal colorectal mucosa/tumor tissue paired (NCM-TT) cohorts. Of the 231 cetuximab signature genes, 57 exhibited an inverse correlation between the methylation of promoter CpG sites and gene expression level in multiple cohorts. About two-thirds of the promoter CpG sites associated with the 57 genes exhibited this correlation. In all 57 gene promoter regions, the methylation levels in NCMs did not differ according to comparisons based on cetuximab signature or DNA methylation status classification of matched TTs. Thus, the altered expression of 57 genes was caused by aberrant DNA methylation during carcinogenesis. Analysis of the association between cetuximab signature or DNA methylation status and progression-free survival (PFS) of anti-EGFR antibody agents in the same cohort showed that DNA methylation status was most associated with PFS. In conclusion, we found that aberrant DNA methylation regulates specific gene expression in cetuximab signature during carcinogenesis, suggesting that it is one of the important determinants of sensitivity to anti-EGFR antibody agents.

Antibiotic therapy augments the efficacy of gemcitabine-containing regimens for advanced cancer: a retrospective study.

BACKGROUND: The addition of antibiotics reportedly augments the efficacy of gemcitabine (GEM) in tumor-bearing mice. However, whether this phenomenon is also observed in cancer patients remains unclear. In the present study, we aimed to assess whether antibiotics for treatment or prevention of infection augments treatment efficacies of GEM-containing regimens in patients with any type of cancer. METHODS: Medical records of patients diagnosed with cancer histopathologically and treated with GEM-containing regimens (n=169) were retrospectively reviewed. Patients were assigned into two groups: antibiotics-untreated group (patients who were treated with GEM-containing regimens but without antibiotics) and antibiotics-treated group (patients who were treated with GEM-containing regimens plus antibiotics). Response rates, progression-free survival (PFS) time, and overall survival (OS) time were analyzed for each group. RESULTS: The response rates of the antibiotics-untreated and antibiotics-treated groups with GEM-containing regimens were 15.1% and 27.6%, respectively. The median PFS times of the antibiotics-untreated and antibiotics-treated groups were 2.5 (95% CI: 1.86-3.73) and 4.9 (95% CI: 3.47-6.0) months, respectively. The median OS times of the antibiotics-untreated and antibiotics-treated groups were 7.53 (95% CI: 5.63-9.57) months and 13.83 (95% CI: 10.83-16.43) months, respectively. CONCLUSION: The addition of antibiotics augments the treatment efficacies of GEM-containing regimens, and it may be a potential therapeutic option to improve treatment efficacies of GEM-containing regimens in patients with advanced cancer.