KRAS phosphorylation regulates cell polarization and tumorigenic properties in colorectal cancer.

Oncogenic mutations of KRAS are found in the most aggressive human tumors, including colorectal cancer. It has been suggested that oncogenic KRAS phosphorylation at Ser181 modulates its activity and favors cell transformation. Using nonphosphorylatable (S181A), phosphomimetic (S181D), and phospho-/dephosphorylatable (S181) oncogenic KRAS mutants, we analyzed the role of this phosphorylation to the maintenance of tumorigenic properties of colorectal cancer cells. Our data show that the presence of phospho-/dephosphorylatable oncogenic KRAS is required for preserving the epithelial organization of colorectal cancer cells in 3D cultures, and for supporting subcutaneous tumor growth in mice. Interestingly, gene expression differed according to the phosphorylation status of KRAS. In DLD-1 cells, CTNNA1 was only expressed in phospho-/dephosphorylatable oncogenic KRAS-expressing cells, correlating with cell polarization. Moreover, lack of oncogenic KRAS phosphorylation leads to changes in expression of genes related to cell invasion, such as SERPINE1, PRSS1,2,3, and NEO1, and expression of phosphomimetic oncogenic KRAS resulted in diminished expression of genes involved in enterocyte differentiation, such as HNF4G. Finally, the analysis, in a public data set of human colorectal cancer, of the gene expression signatures associated with phosphomimetic and nonphosphorylatable oncogenic KRAS suggests that this post-translational modification regulates tumor progression in patients

Kras oncogene ablation prevents resistance in advanced lung adenocarcinomas

KRASG12C inhibitors have revolutionized the clinical management of patients with KRASG12C-mutant lung adenocarcinoma. However, patient exposure to these inhibitors leads to the rapid onset of resistance. In this study, we have used genetically engineered mice to compare the therapeutic efficacy and the emergence of tumor resistance between genetic ablation of mutant Kras expression and pharmacological inhibition of oncogenic KRAS activity. Whereas Kras ablation induces massive tumor regression and prevents the appearance of resistant cells in vivo, treatment of KrasG12C/Trp53-driven lung adenocarcinomas with sotorasib, a selective KRASG12C inhibitor, caused a limited antitumor response similar to that observed in the clinic, including the rapid onset of resistance. Unlike in human tumors, we did not observe mutations in components of the RAS-signaling pathways. Instead, sotorasib-resistant tumors displayed amplification of the mutant Kras allele and activation of xenobiotic metabolism pathways, suggesting that reduction of the on-target activity of KRASG12C inhibitors is the main mechanism responsible for the onset of resistance. In sum, our results suggest that resistance to KRAS inhibitors could be prevented by achieving a more robust inhibition of KRAS signaling mimicking the results obtained upon Kras ablation.This work was supported by grants from the European Research Council (ERC-GA 695566, THERACAN); the Agencia Estatal de Investigación, Ministerio de Ciencia e Innovación (MCIN/AEI/10.13039/501100011033) (grant RTC2017-6576-1), cofunded by ERDF “A way of making Europe”; the Autonomous Community of Madrid (B2017/BMD-3884 iLung-CM), cofunded by FSE and ERDF “A way of making Europe”; the CRIS Cancer Foundation, the Scientific Foundation of the Spanish Association Against Cancer (GC166173694BARB); an ERA PerMed grant, funded by the Instituto de Salud Carlos III (AC20/00114), the Scientific Foundation of the Spanish Association Against Cancer (PERME20707BARB) and the European Union’s Horizon 2020 program (779282) to MB; and the Agencia Estatal de Investigación, Ministerio de Ciencia e Innovación (grant RTI2018-094664-B-I00), cofunded by ERDF “A way of making Europe” to MM and MB. Additional funding included grants from the Spanish National Research and Development Plan, Instituto de Salud Carlos III, ERDF “A way of making Europe” (PI20/01837 and DTS19/00111); the Scientific Foundation of the Spanish Association Against Cancer (LABAE20049RODR) to SRP; the Instituto de Salud Carlos III (PI19/00514), cofunded by ERDF “A way of making Europe” to CG; the Agencia Estatal de Investigación, Ministerio de Ciencia e Innovación (grant PID2020-116705RB-I00); and the Scientific Foundation of the Spanish Association Against Cancer (LABAE211678DROS) to MD. MB is a recipient of an endowed chair from the AXA Research Fund. M Salmón was supported by a predoctoral contract “Severo Ochoa” (BES-2016-079096) from the Agencia Estatal de Investigación, Ministerio de Ciencia e Innovación. OB is a recipient of a fellowship from the Formación de Personal Investigador (FPI) program of the Agencia Estatal de Investigación, Ministerio de Ciencia e Innovación. FFG was supported by a Formación de Profesorado Universitario (FPU) fellowship from the Ministerio de Universidades

Network meta‐analysis of post‐exposure prophylaxis randomized clinical trials

Objectives: We performed a network meta‐analysis of PEP randomized clinical trials to evaluate the best regimen. / Methods: After MEDLINE/Pubmed search, studies were included if: (1) were randomized, (2) comparing at least 2 PEP three‐drug regimens and, (3) reported completion rates or discontinuation at 28 days. Five studies with 1105 PEP initiations were included and compared ritonavir‐boosted lopinavir (LPV/r) vs. atazanavir (ATV) (one study), cobicistat‐boosted elvitegravir (EVG/c) (one study), raltegravir (RAL) (one study) or maraviroc (MVC) (two studies). We estimated the probability of each treatment of being the best based on the evaluation of five outcomes: PEP non‐completion at day 28, PEP discontinuation due to adverse events, PEP switching due to any cause, lost to follow‐up and adverse events. / Results: Participants were mostly men who have sex with men (n = 832, 75%) with non‐occupational exposure to HIV (89.86%). Four‐hundred fifty‐four (41%) participants failed to complete their PEP course for any reason. The Odds Ratio (OR) for PEP non‐completion at day 28 in each antiretroviral compared to LPV/r was: ATV 0.95 (95% CI 0.58–1.56; EVG/c: OR 0.65 95% CI 0.30–1.37; RAL: OR 0.68 95% CI 0.41–1.13; and MVC: OR 0.69 95% CI 0.47–1.01. In addition, the rankogram showed that EVG/c had the highest probability of being the best treatment for the lowest rates in PEP non‐completion at day 28, switching, lost to follow‐up or adverse events and MVC for PEP discontinuations due to adverse events. / Conclusions: Our study shows the advantages of integrase inhibitors when used as PEP, particularly EVG as a Single‐Tablet Regimen

Near-Side, Far-Side, Uphill, Downhill: Impact of Bus Stop Location on Bus Delay

One of the factors affecting where bus stops should be located is the expected delay associated with the stop location. On hills, the effect of gravity on already weak diesel engines can lead to considerable additional delay if a bus has to accelerate from a stop. An empirical bus acceleration profile, modified to account for gravity, was applied to constant grade, sag curve, and crest curve profiles. The marginal impact of grade on stopping delay ranged from –4 to 11 s, depending on grade. At signalized intersections, a deterministic model was created that accounted for deceleration, acceleration, and queue interference. Relative to a stop placed away from an intersection, far-side stop placement either causes a very small reduction in delay or has no effect. Near-side placement can reduce delay in a few cases such as reserved bus lanes, but more often it increases delay, sometimes considerably depending on factors such as red ratio, volume:capacity ratio, cycle length, and stop setback. Measures that reduce interference with the queue tend to reduce the net delay from a near-side location; these measures include increasing stop setback, shortening cycle length, and giving the bus a (near) exclusive lane. Results are presented with default adjustments for hills and signalized intersections that can be used in the context of a stop spacing study