Prolyl hydroxylase domain 3 influences the radiotherapy efficacy of pancreatic cancer cells by targeting hypoxia-inducible factor-1α.

PURPOSE: Pancreatic cancer is characterized by a hypoxic microenvironment and resistance to most currently available treatment modalities. Prolyl hydroxylase domain 3 (PHD3) is a rate-limiting enzyme that regulates the degradation of hypoxia-inducible factors (HIFs) and is deregulated in pancreatic cancer cells. Whether such alteration of PHD3 expression contributes to the sustained growth and radioresistance of pancreatic cancer cells remains largely unknown. MATERIALS AND METHODS: PHD3 was overexpressed in pancreatic cancer Mia-paca2 cells via lentiviral expression. Cell cycle progression and apoptosis were assayed by flow cytometry. HIF-1α, EGFR, and PHD3 protein expression was assessed by Western blotting. Cell survival was determined in a colony formation assay. RESULTS: PHD3 overexpression suppressed HIF-1α protein expression and EGFR phosphorylation and enhanced the 2 Gy irradiation-mediated reductions in HIF-1α and phosphorylated (p)-EGFR under either normoxic or hypoxic conditions. PHD3 overexpression inhibited the growth and colony formation of Mia-paca2 cells in response to irradiation under either normoxic or hypoxic conditions. PHD3 overexpression exacerbated irradiation-induced apoptosis, with a greater effect under hypoxia than normoxia. Cell cycle distribution analysis demonstrated that PHD3 overexpression resulted in further shortened S phase and lengthened G2/M phase in response to irradiation. CONCLUSION: PHD3 expression may contribute to the radiotherapy efficacy of pancreatic cancer cells and serve as a novel biomarker for improving radiotherapy efficacy in pancreatic cancer.

Survival benefit of re-irradiation in esophageal Cancer patients with Locoregional recurrence: a propensity score-matched analysis.

BACKGROUND: To investigate the treatment failure pattern and factors influencing locoregional recurrence of esophageal squamous cell carcinoma (ESCC) and examine patient survival with re-irradiation (re-RT) after primary radiotherapy. METHODS: We retrospectively analyzed 87 ESCC patients treated initially with radiotherapy. Failure patterns were classified into regional lymph node recurrence only (LN) and primary failure with/without regional lymph node recurrence (PF). Patients received either re-RT or other treatments (non-re-RT group). Baseline covariates were balanced by a propensity score model. Overall survival (OS) and toxicities were assessed as outcomes. RESULTS: The median follow-up time was 87 months. Thirty-nine patients received re-RT. Failure pattern and re-RT were independent prognostic factors for OS (P = 0.040 and 0.015) by Cox multivariate analysis. Re-RT with concomitant chemotherapy showed no survival benefit over re-RT alone (P = 0.70). No differences in characteristics were found between the groups by Chi-square tests after propensity score matching. The Cox model showed that failure pattern and re-RT were prognostic factors with hazard ratios (HR) of 0.319 (P = 0.025) and 0.375 (P = 0.002), respectively, in the matched cohort. Significant differences in OS were observed according to failure pattern (P = 0.004) and re-RT (P < 0.001). In the re-RT and non-re-RT groups, 9.09% and 3.03% of patients experienced tracheoesophageal fistulas, and 15.15% and 3.03% of patients developed pericardial/pleural effusion, respectively (P > 0.05). The incidence of radiation pneumonitis was higher in the re-RT group (24.24% vs. 6.06%, P = 0.039), but no cases of pneumonia-related death occurred. CONCLUSIONS: Re-RT improved long-term survival in patients with locoregional recurrent ESCC. Despite a high incidence of radiation pneumonitis, toxicities were tolerable.

[Improvement of the the thermostability of Penicillium expansum lipase by mutagenesis the random mutant ep8 at K55R].

In order to improve the thermostability of the Penicillium expansum Lipase (PEL), the lipase encoding genes was mutated by site-directed mutagenesis. A recombinant vector pAO815-ep8-K55R which contain double mutant genes was constructed by overlap extension PCR using the cDNA of a random-mutant lipase ep8 (a single site mutant) as the template and two special primers were used to generate another mutation site K55R. The recombinant vector was transformed into Pichia pastoris GS115 by electroporation and the recombinant mutant GS-pAO815-ep8- K55R can secret double-mutant lipase PEL-ep8-K55R-GS into the medium when it was induced by Methanol. The yield of the double-mutant lipase is 508 u/mL, which is 81% that of the wild type lipase PEL-GS (627 u/mL) and 55% that of random-mutant PEL-ep8-GS (924 u/mL). The specific activity of double-mutant lipase is 2309.1 u/mg, which is similar to random-mutant lipase PEL-ep8-GS and the wild type lipase PEL-GS. The optimum temperature of the double-mutant lipase is same with the wild type lipase PEL-GS and random-mutant lipase PEL-ep8-GS. While the Tm of the double-mutant lipase is 41.0 degrees C, 2.3 degrees C higher than the wild type lipase PEL-GS and 0.8% higher than the random-mutant lipase PEL-ep8-GS, indicating that the double-mutant lipase PEL-ep8-K55R-GS has higher thermostability.