Kai Qin

BACKGROUND: Although a substantial increase in the survival of patients with other cancers has been observed in recent decades, pancreatic ductal adenocarcinoma (PDAC) remains one of the deadliest diseases. No effective screening approach exists. METHODS: Differential exosomal long noncoding RNAs (lncRNAs) isolated from the serum of patients with PDAC and healthy individuals were profiled to screen for potential markers in liquid biopsies. The functions of LINC00623 in PDAC cell proliferation, migration and invasion were confirmed through in vivo and in vitro assays. RNA pulldown, RNA immunoprecipitation (RIP) and coimmunoprecipitation (Co-IP) assays and rescue experiments were performed to explore the molecular mechanisms of the LINC00623/NAT10 signaling axis in PDAC progression. RESULTS: A novel lncRNA, LINC00623, was identified, and its diagnostic value was confirmed, as it could discriminate patients with PDAC from patients with benign pancreatic neoplasms and healthy individuals. Moreover, LINC00623 was shown to promote the tumorigenicity and migratory capacity of PDAC cells in vitro and in vivo. Mechanistically, LINC00623 bound to N-acetyltransferase 10 (NAT10) and blocked its ubiquitination-dependent degradation by recruiting the deubiquitinase USP39. As a key regulator of N4-acetylcytidine (ac4C) modification of mRNA, NAT10 was demonstrated to maintain the stability of oncogenic mRNAs and promote their translation efficiency through ac4C modification. CONCLUSIONS: Our data revealed the role of LINC00623/NAT10 signaling axis in PDAC progression, showing that it is a potential biomarker and therapeutic target for PDAC.

Cellulose without any pretreatment was directly converted into levulinic acid (LA) in a microwave-assisted acidic catalytic system with a high ionic strength. The highest LA yield could reach 67.3 mol% within 60 min even when the cellulose concentration was as high as 10 wt%. It is concluded that high ion strength and microwave irradiation were jointly responsible for the fast cellulose conversion and high LA yield, and a cooperative acceleration mechanism is finally proposed. The high ion concentration provided by alkali metal halides not only accelerated the cellulose hydrolysis but also facilitated glucose conversion into LA by shifting the weak acid ionization equilibria, and microwave irradiation further promoted this salt effect by its characteristic heating way of ion conduction. Such a one-pot catalytic system provides a possibility of practical application for direct highly efficient conversion of cellulose due to its green properties, low cost and efficient characteristics.

Pancreatic cancer is a terminal disease with high mortality and very poor prognosis. A sensitive and quantitative analysis of KRAS mutations in pancreatic cancer provides a tool not only to understand the biological mechanisms of pancreatic cancer but also for diagnosis and treatment monitoring. Digital polymerase chain reaction (PCR) is a promising tool for KRAS mutation analysis, but current methods generally require a complex microfluidic handling system, which can be challenging to implement in routine research and point-of-care clinical diagnostics. Here, we present a droplet-array SlipChip (da-SlipChip) for the multiplex quantification of KRAS G12D, V, R, and C mutant genes with the wild-type (WT) gene background by dual color (FAM/ROX) fluorescence detection. This da-SlipChip is a high-density microwell array of 21,696 wells of 200 pL in 4 by 5424 microwell format with simple loading and slipping operation. It does not require the same precise alignment of microfeatures on the different plates that are acquired by the traditional digital PCR SlipChip. This device can provide accurate quantification of both mutant genes and the WT KRAS gene. We collected tumor tissue, paired normal pancreatic tissue, and other normal tissues from 18 pancreatic cancer patients and analyzed the mutation profiles of KRAS G12D, V, R, and C in these samples; the results from the multiplex digital PCR on da-SlipChip agree well with those of next-generation sequencing (NGS). This da-SlipChip moves digital PCR closer to the practical point-of-care applications not only for detecting KRAS mutations in pancreatic cancer but also for other applications that require precise nucleic acid quantification with high sensitivity.