SOX9 regulates ERBB signalling in pancreatic cancer development

OBJECTIVE

The transcription factor SOX9 was recently shown to stimulate ductal gene expression in pancreatic acinar-to-ductal metaplasia and to accelerate development of premalignant lesions preceding pancreatic ductal adenocarcinoma (PDAC). Here, we investigate how SOX9 operates in pancreatic tumourigenesis.

DESIGN

We analysed genomic and transcriptomic data from surgically resected PDAC and extended the expression analysis to xenografts from PDAC samples and to PDAC cell lines. SOX9 expression was manipulated in human cell lines and mouse models developing PDAC.

RESULTS

We found genetic aberrations in the SOX9 gene in about 15% of patient tumours. Most PDAC samples strongly express SOX9 protein, and SOX9 levels are higher in classical PDAC. This tumour subtype is associated with better patient outcome, and cell lines of this subtype respond to therapy targeting epidermal growth factor receptor (EGFR/ERBB1) signalling, a pathway essential for pancreatic tumourigenesis. In human PDAC, high expression of SOX9 correlates with expression of genes belonging to the ERBB pathway. In particular, ERBB2 expression in PDAC cell lines is stimulated by SOX9. Inactivating Sox9 expression in mice confirmed its role in PDAC initiation; it demonstrated that Sox9 stimulates expression of several members of the ERBB pathway and is required for ERBB signalling activity.

CONCLUSIONS

By integrating data from patient samples and mouse models, we found that SOX9 regulates the ERBB pathway throughout pancreatic tumourigenesis. Our work opens perspectives for therapy targeting tumourigenic mechanisms.

Polyswitch lentivectors: "all-in-one" lentiviral vectors for drug-inducible gene expression, live selection, and recombination cloning

Lentiviral vectors are now widely considered one of the safest and most efficient tools for gene delivery and stable gene expression. Even though inducible gene expression cassettes are mandatory for many genetic engineering strategies, most current systems suffer from various issues, such as the requirement of two vectors, which decreases the overall efficiency of the transduction, leakiness and/or insufficient levels of activation of the inducible promoter, lack of selectable marker, low titers, or general issues associated with the cloning of large plasmids. In this article, we describe the design and functional characterization of a set of "all-in-one" multicistronic autoinducible lentivectors. They combine: (1) an optimized drug-inducible promoter; (2) a multicistronic strategy to express living color, selectable marker, and transactivator; and (3) acceptor sites for easy recombination cloning of genes of interest. These polyswitch lentivectors have good titers, very low basal activity, and reversible high induced activity, and can accept a growing number of genes already cloned in entry plasmids. These combined features make them a novel, powerful, and versatile tool for current and future genetic engineering approaches.

Lentiviral vectors

Lentiviral vectors have evolved over the last decade as powerful, reliable, and safe tools for stable gene transfer in a wide variety of mammalian cells. Contrary to other vectors derived from oncoretroviruses, they allow for stable gene delivery into most nondividing primary cells. In particular, lentivectors (LVs) derived from HIV-1 have gradually evolved to display many desirable features aimed at increasing both their safety and their versatility. This is why lentiviral vectors are becoming the most useful and promising tools for genetic engineering, to generate cells that can be used for research, diagnosis, and therapy. This chapter describes protocols and guidelines, for production and titration of LVs, which can be implemented in a research laboratory setting, with an emphasis on standardization in order to improve transposability of results between laboratories. We also discuss latest designs in LV technology.