Recurrence risk evaluation in T1N1M0/T2N0M0/T3N0M0 gastric cancer with TP53 codon 72 polymorphisms.

BACKGROUND: Postoperative adjuvant chemotherapy is not indicated for T1N1M0/T2N0M0/T3N0M0 gastric cancer. However, approximately 10% to 30% of these patients experience recurrence and metastasis. METHODS: Among 658 patients with gastric cancer who received gastrectomy with curative intent, 130 T1N1M0/T2N0M0 and 73 T3N0M0 patients were enrolled. Overall survival (OS) and relapse-free survival (RFS) were analyzed based on TP53 codon 72 polymorphisms Arg/Arg, Arg/Pro, and Pro/Pro. The hazard ratio (HR) for each subgroup was compared by TP53 codon 72 polymorphisms. RESULTS: Of the 189 patients for whom polymorphism analysis results were available, the 5- and 10-year OS was 84.9% and 65.1%, respectively. The 5- and 10-year RFS was 81.8% and 65.4%, respectively. When the study cohort was divided into two groups according to polymorphism status (ie, "Arg/Arg and Arg/Pro" vs Pro/Pro), both the OS (HR, 2.799; 95% confidence interval [CI], 1.071-7.315; P = .036) and RFS (HR, 2.639; 95% CI, 1.025-6.794; P = .044) of the Pro/Pro group were significantly lower than those for the Arg/Arg and Arg/Pro groups across the entire observation period. CONCLUSIONS: The TP53 codon 72 Pro/Pro polymorphism may isolate a relatively high-risk patient group in T1N1M0/T2N0M0/T3N0M0 gastric cancer.

Helicobacter pylori infection is associated with favorable outcome in advanced gastric cancer patients treated with S-1 adjuvant chemotherapy.

BACKGROUND AND OBJECTIVES: Limited information exists regarding beneficial effects of Helicobacter pylori. To examine the effect in advanced gastric cancer, we compared survival for patients treated with surgery-only or adjuvant chemotherapy on the basis of H. pylori infection status. METHODS: A cohort of 491 patients who underwent R0 resection for locally advanced gastric cancer between 2000 and 2009 at 12 institutions in northern Japan was included. H. pylori infection status, was assessed from paraffin-embedded formalin-fixed samples. Overall survival (OS) and disease-free survival (DFS) in surgery-only (Surgery) and adjuvant chemotherapy (S-1) groups were analyzed. A propensity score matching was employed to correct for confounding factors by indication. RESULTS: H. pylori infection was positive in 175 patients and negative in 316 patients. H. pylori-positive patients showed significantly better survival than H. pylori-negative patients in both OS (hazard ratio [HR] 0.593, 95% confidence interval [CI] 0.417-0.843; P = 0.003]) and DFS (HR 0.679, 95%CI 0.492-0.937; P = 0.018). Propensity score matching further confirmed that S-1 was virtually only effective when tumors were H. pylori-positive. CONCLUSIONS: The favorable outcome of H. pylori-positive patients implies that the host immune system is modulated by H. pylori enhancing the chemotherapeutic efficacy.

Inhibition of PI3K suppresses propagation of drug-tolerant cancer cell subpopulations enriched by 5-fluorouracil.

Drug-tolerant cancer cell subpopulations are responsible for relapse after chemotherapy. By continuously exposing the gastric cancer cell line MKN45 to 5-FU for >100 passages, we established a 5-fluorouracil (5-FU)-tolerant line, MKN45/5FU. Orthotopic xenografts of MKN45/5FU cells in the stomach of nude mice revealed that these cells had a high potential to metastasize to sites such as the liver. Levels of phosphorylated phosphatidylinositide 3-kinase (PI3K) increased both in 5-FU-tolerant subpopulations according to the 5-FU dose, and in gastric submucosal orthotopic xenografts of MKN45/5FU cells. Sequential administration of 5-FU and a PI3K inhibitor, GDC-0941, targeted the downstream ribosomal S6 kinase phosphorylation to significantly suppress 5-FU-tolerant subpopulations and tumor propagation of orthotopic MKN45/5FU xenografts. These results suggest that administration of 5-FU followed by GDC-0941 may suppress disease relapse after 5-FU-based gastric cancer chemotherapy.

α-Amanitin Restrains Cancer Relapse from Drug-Tolerant Cell Subpopulations via TAF15.

Cancer relapse occurs with substantial frequency even after treatment with curative intent. Here we studied drug-tolerant colonies (DTCs), which are subpopulations of cancer cells that survive in the presence of drugs. Proteomic characterization of DTCs identified stemness- and epithelial-dominant subpopulations, but functional screening suggested that DTC formation was regulated at the transcriptional level independent from protein expression patterns. We consistently found that α-amanitin, an RNA polymerase II (RNAPII) inhibitor, effectively inhibited DTCs by suppressing TAF15 expression, which binds to RNA to modulate transcription and RNA processing. Sequential administration of α-amanitin and cisplatin extended overall survival in a cancer-relapse mouse model, namely peritonitis carcinomatosa. Therefore, post-treatment cancer relapse may occur through non-distinct subpopulations and may be effectively prevented by α-amanitin to disrupt transcriptional machinery, including TAF15.

Accumulation of nitrate and nitrite in chilled leaves of rice seedlings is induced by high root temperature.

We previously found a novel type of chilling injury in the leaves of rice seedlings (Oryza sativa L. cv. Akitakomachi). The damage was only observed when the roots were not chilled (10 °C/25 °C, shoots/roots), but not when the whole seedling was chilled (10 °C/10 °C). In this report, we show that the chilling injury induced by high root temperature required nitrate and potassium together with a trace amount of iron, manganese or both in the nutrient solution during the treatment, and that the injury was increased by nitrogen starvation before chilling. Both nitrate and nitrite accumulated in the 10 °C/25 °C leaves when the nutrient solution contained nitrate. The nitrate accumulation in the 10 °C/25 °C leaves was highest at the end of the first light period, and was followed by a decrease with a concomitant increase in nitrite during the first dark period. The photosynthetic electron transport was completely lost in both PSII and PSI in the 10 °C/25 °C leaves when the nutrient solution contained nitrate. However, the activities in the leaves of the 10 °C/25 °C plants treated with the nutrient solution lacking nitrate remained at approximately half those in the 10 °C/10°C leaves. The photochemical quenching of Chl fluorescence and the P700 oxidation state were also intermediate between those in the 10 °C/25 °C and 10 °C/10°C leaves of plants supplied with the complete nutrients. Thus, the chilling injury was closely linked to the accumulation of nitrate and nitrite, as well as to a malfunction of photosynthesis in the 10 °C/25 °C leaves.

High root temperature blocks both linear and cyclic electron transport in the dark during chilling of the leaves of rice seedlings.

The most photosynthetically active leaves of rice seedlings were severely damaged when shoots but not roots were chilled (10°C/25°C, respectively), but no such injury was observed when the whole seedling was chilled (10°C/10°C). To elucidate the mechanisms, we compared the photosynthetic characteristics of the seedlings during the dark chilling treatments. Simultaneous analyses of Chl fluorescence and the change in absorbance of P700 showed that electron transport almost disappeared in both PSII and PSI in the 10°C/25°C leaves, whereas the electron transport rate in PSI in the 10°C/10°C leaves was similar to or higher than that in non-chilled control leaves. Light-induced non-photochemical quenching in PSII was inhibited in the 10°C/25°C leaves, occurring at only half the level in the 10°C/10°C leaves, whereas non-light-induced non-photochemical quenching remained high in the 10°C/25°C leaves. The light induction of Chl a fluorescence (OJIP curves) in the 10°C/25°C leaves was similar to that in leaves treated with DCMU. The fluorescence decay after a single turnover saturating flash in the 10°C/25°C leaves was much slower than in the 10°C/10°C leaves. In vivo analyses of the 550-515 nm difference signal indicated decreased formation of a proton gradient across the thylakoid membrane and decreased zeaxanthin formation in the 10°C/25°C leaves. Our results suggest that electron transport was blocked between Q(A) and Q(B) in the dark 10°C/25°C leaves, but without irreversible damage to the components of this system. The consequent light-dependent losses of electron transport, proton gradient formation across the thylakoids and thermal dissipation may therefore be responsible for the visible injury.