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Allele-specific signaling by different KRAS alleles remains poorly understood. The KRAS G12R mutation displays uneven prevalence among cancers that harbor the highest occurrence of KRAS mutations: it is rare in lung and colorectal cancers (~1%), yet relatively common (~20%) in pancreatic ductal adenocarcinoma (PDAC), suggesting context-specific properties. We evaluated whether KRAS G12R is functionally distinct from the more common KRAS G12D or KRAS G12V mutant proteins (KRAS G12D/V ). We found that KRAS G12D/V but not KRAS G12R drives macropinocytosis and that MYC is essential for macropinocytosis in KRAS G12D/V but not KRAS G12R -mutant PDAC. Surprisingly, we found that KRAS G12R is defective for interaction with a key effector, p110α phosphoinositide 3-kinase (PI3Kα), due to structural perturbations in switch II. Instead, upregulated KRAS-independent PI3Kγ activity was able to support macropinocytosis in KRAS G12R -mutant PDAC. Finally, we determined that KRAS G12R -mutant PDAC displayed a distinct drug sensitivity profile compared with KRAS G12D -mutant PDAC but is still responsive to the combined inhibition of ERK and autophagy.Hobbs et al.

BackgroundFollowing the completion of treatment and as they enter the follow-up phase, breast cancer patients (BCPs) often recount feeling ‘lost in transition’, and are left with many questions concerning how their ongoing care and monitoring for recurrence will be managed. Family physicians (FPs) also frequently report feeling ill-equipped to provide follow-up care to BCPs. In this three-phase qualitative pilot study we designed, implemented and evaluated a multi-faceted survivorship care plan (SCP) to address the information needs of BCPs at our facility and of their FPs.MethodsIn Phase 1 focus groups and individual interviews were conducted with 35 participants from three stakeholder groups (BCPs, FPs and oncology specialist health care providers (OHCPs)), to identify specific information needs. An SCP was then designed based on these findings, consisting of both web-based and paper-based tools (Phase 2). For Phase 3, both sets of tools were subsequently evaluated via focus groups and interviews with 26 participants. Interviews and focus groups were audio taped, transcribed and content analysed for emergent themes and patterns.ResultsIn Phase 1 patients commented that web-based, paper-based and human resources components were desirable in any SCP. Patients did not focus exclusively on the post-treatment period, but instead spoke of evolving needs throughout their cancer journey. FPs indicated that any tools to support them must distill important information in a user-friendly format. In Phase 2, a pilot SCP was subsequently designed, consisting of both web-based and paper-based materials tailored specifically to the needs of BCPs as well as FPs. During Phase 3 (evaluation) BCPs indicated that the SCP was effective at addressing many of their needs, and offered suggestions for future improvements. Both patients and FPs found the pilot SCP to be an improvement from the previous standard of care. Patients perceived the quality of the BCP-FP relationship as integral to their comfort with FPs assuming follow-up responsibilities.ConclusionsThis pilot multi-component SCP shows promise in addressing the information needs of BCPs and the FPs who care for them. Next steps include refinement of the different SCP components, further evaluation (including usability testing), and planning for more extensive implementation.

Topoisomerases are ubiquitous proteins found in all three domains of life. They change the topology of DNA via transient breaks on either one or two of the DNA strands to allow passage of another single or double DNA strand through the break. Topoisomerases are classified into two types: type I enzymes cleave one DNA strand and pass either one or two DNA strands through the break before resealing it, while type II molecules cleave both DNA strands in concert and pass another double strand through the break followed by religation of the double strand break. Here we review recent work on the structure of type I enzymes. These structural studies are providing atomic details that, together with the existing wealth of biochemical and biophysical data, are bringing our understanding of the mechanism of action of these enzymes to the atomic level.

Lipoxins (LX) are a class of eicosanoid that possesses a wide spectrum of antiinflammatory and proresolution bioactions. Here we have investigated the impact of the endogenously produced eicosanoid LXA4 on endothelial cell inflammatory, proliferative, and antigenic responses. Using HUVECs we demonstrate that LXA4 inhibits vascular endothelial growth factor (VEGF)-stimulated inflammatory responses including IL-6, TNF-α, IFN-γ and IL-8 secretion, as well as endothelial ICAM-1 expression. Interestingly, LXA4 up-regulated IL-10 production from HUVECs. Consistent with these antiinflammatory and proresolution responses to LXA4, we demonstrate that LXA4 inhibited leukotriene D4 and VEGF-stimulated proliferation and angiogenesis as determined by tube formation of HUVECs. We have explored the underlying molecular mechanisms and demonstrate that LXA4 pretreatment is associated with the decrease of VEGF-stimulated VEGF receptor 2 (KDR/FLK-1) phosphorylation and downstream signaling events including activation of phospholipase C-γ, ERK1/2, and Akt.

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