Pancreatic ductal adenocarcinoma (PDAC) develops a pronounced stromal response reflecting an aberrant wound-healing process. This stromal reaction features trans-differentiation of tissue-resident pancreatic stellate cells (PSCs) into activated cancer-associated fibroblasts (CAFs), a process induced by PDAC cells but of unclear significance for PDAC progression. Here we show that PSCs undergo a dramatic lipid metabolic shift during differentiation in the context of pancreatic tumorigenesis, including remodeling of the intracellular lipidome and secretion of abundant lipids in the activated, fibroblastic state. Specifically, stroma-derived lysophosphatidylcholines support PDAC cell synthesis of phosphatidylcholines, key components of cell membranes, and also facilitate production of the potent wound-healing mediator lysophosphatidic acid (LPA) by the extracellular enzyme autotaxin, which is overexpressed in PDAC. The autotaxin-LPA axis promotes PDAC cell proliferation, migration and AKT activation, and genetic or pharmacologic autotaxin inhibition suppresses PDAC growth in vivo. Our work demonstrates how PDAC cells exploit the local production of wound healing mediators to stimulate their own growth and migration.

HighlightsAMPK is activated by oxidative stress generated using glucose oxidase.Activation is largely, but not solely, mediated by increases in AMP and/or ADP.Increases in Thr172 phosphorylation are mediated by inhibition of dephosphorylation.

SummarySU6656, a Src kinase inhibitor, was reported to increase fat oxidation and reduce body weight in mice, with proposed mechanisms involving AMP-activated protein kinase (AMPK) activation via inhibition of phosphorylation of either LKB1 or AMPK by the Src kinase, Fyn. However, we report that AMPK activation by SU6656 is independent of Src kinases or tyrosine phosphorylation of LKB1 or AMPK and is not due to decreased cellular energy status or binding at the ADaM site on AMPK. SU6656 is a potent AMPK inhibitor, yet binding at the catalytic site paradoxically promotes phosphorylation of Thr172 by LKB1. This would enhance phosphorylation of downstream targets provided the lifetime of Thr172 phosphorylation was sufficient to allow dissociation of the inhibitor and subsequent catalysis prior to its dephosphorylation. By contrast, sorafenib, a kinase inhibitor in clinical use, activates AMPK indirectly by inhibiting mitochondrial metabolism and increasing cellular AMP:ADP and/or ADP:ATP ratios.

Graphical Abstract Highlights d PTEN loss increases scavenging, conferring resistance to mTOR inhibition in PDAC d mTORC2 selectively regulates macropinocytosis independently of its kinase activity d Protein scavenging restores pAkt serine 473, leading to recovery of proliferation d Lysosomal blockade eliminates the protein-mediated resistance to mTOR inhibition

<p>Table S1</p>

<p>Table S2</p>

<p>Figure S1-S5 with legends</p>

<p>Table S1</p>