Pancreatic cancer with synchronous liver and colon metastases: A case report.

BACKGROUND: Metastasis of pancreatic cancer to the colon is rare and the features need to be further elucidated. Herein, we report a rare case of pancreatic cancer with simultaneous liver and colon metastases. CASE SUMMARY: A 48-year-old man with intrahepatic space-occupying lesions based on a computed tomography scan was admitted to our hospital for further treatment. Abdominal magnetic resonance imaging revealed a 6.4 cm × 4.2 cm mass in the tail of the pancreas and multiple low-density masses in the liver parenchyma. In addition, a mass of 2.2 cm × 1.6 cm with surface congestive erosions in the sigmoid colon was detected by colonoscopy. Histopathological examination of biopsies from both the liver and colon lesions revealed a moderately to poorly differentiated adenocarcinoma. Immunohistochemical staining of the colon tumor was positive for cytokeratin (CK) 7 and CK, but negative for colorectal adenocarcinoma-related markers CK 20, CDX2, and SATB2, thus indicating that the metastasis originated from the pancreas. Next-generation sequencing for genomic profiling of the liver and colon metastases both found mutations in KRAS (p.G12D) and TP53 (c.376-1delG), with microsatellite stable and low tumor mutational burden without actionable or cancer-predisposing gene mutations detected. The patient was subsequently treated with 12 cycles of FOLFIRINOX which led to a sustainable response, followed by ongoing maintenance treatment with irinotecan plus fluorouracil. CONCLUSION: For this rare case, careful evaluation of histopathological and immunohistochemical staining results are required. The genomic profiling of colon lesions was revealed for the first time, and FOLFIRINOX showed good treatment efficacy in this patient.

Development of a fast and easy method for Escherichia coli genome editing with CRISPR/Cas9.

BACKGROUND: Microbial genome editing is a powerful tool to modify chromosome in way of deletion, insertion or replacement, which is one of the most important techniques in metabolic engineering research. The emergence of CRISPR/Cas9 technique inspires various genomic editing methods. RESULTS: In this research, the goal of development of a fast and easy method for Escherichia coli genome editing with high efficiency is pursued. For this purpose, we designed modular plasmid assembly strategy, compared effects of different length of homologous arms for recombination, and tested different sets of recombinases. The final technique we developed only requires one plasmid construction and one transformation of practice to edit a genomic locus with 3 days and minimal lab work. In addition, the single temperature sensitive plasmid is easy to eliminate for another round of editing. Especially, process of the modularized editing plasmid construction only takes 4 h. CONCLUSION: In this study, we developed a fast and easy genome editing procedure based on CRISPR/Cas9 system that only required the work of one plasmid construction and one transformation, which allowed modification of a chromosome locus within 3 days and could be performed continuously for multiple loci.

Engineering Corynebacterium glutamicum for violacein hyper production.

BACKGROUND: Corynebacterium glutamicum was used as a metabolic engineering chassis for production of crude violacein (mixture of violacein and deoxyviolacein) due to Corynebacterium's GRAS status and advantages in tryptophan fermentation. The violacein is a commercially potential compound with various applications derived from L-tryptophan. RESULTS: Corynebacterium glutamicum ATCC 21850 that could produce 162.98 mg L(-1) tryptophan was employed as a novel host for metabolic engineering chassis. Heterologous vio operon from Chromobacterium violaceum was over-expressed in ATCC 21850 strain with constitutive promoter to have obtained 532 mg L(-1) violacein. Considering toxicity of violacein, vio operon was expressed with inducible promoter and 629 mg L(-1) violacein was obtained in batch culture. Due to the economical coding nature of vio operon, the compressed RBS of vio genes were replaced with complete strong C. glutamicum ones. And extended expression units were assembled to form a synthetic operon. With this strategy, 1116 mg L(-1) violacein in batch culture was achieved. Fermentation process was then optimized by studying induction time, induction concentration, culture composition and fermentation temperature. as a result, a titer of 5436 mg L(-1) and a productivity of 47 mg L(-1) h(-1) were achieved in 3 L bioreactor. CONCLUSIONS: With metabolic engineering and fermentation optimization practice, C. glutamicum 21850 (pEC-C-vio1) was able to produce violacein with both titer and productivity at the highest level ever reported. Due to advantages of mature C. glutamicum fermentation industry, this work has built basis for commercial production of violacein.