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Simple Summary: Pancreatic ductal adenocarcinoma continues to be one of the deadliest cancers worldwide. Preclinical studies involving animals rarely include sex as a major biological variable in testing the efficacy of new drugs. In an animal model of pancreatic cancer, we analyzed the impact of sex on the pathological features of the disease and on an experimental small molecule-based therapy tested in vivo for the first time. While the therapy shows potential, the obtained results are confounded by sex-specific effects. This study, therefore, highlights the importance of sex-inclusive research while simultaneously providing a basis for further studies of the therapy tested. Preclinical studies rarely test the efficacy of therapies in both sexes. The field of oncology is no exception in this regard. In a model of syngeneic, orthotopic, metastasized pancreatic ductal adenocarcinoma we evaluated the impact of sex on pathological features of this disease as well as on the efficacy and possible adverse side effects of a novel, small molecule-based therapy inhibiting KRAS:SOS1, MEK1/2 and PI3K signaling in male and female C57BL/6J mice. Male mice had less tumor infiltration of CD8-positive cells, developed bigger tumors, had more lung metastasis and a lower probability of survival compared to female mice. These more severe pathological features in male animals were accompanied by higher distress at the end of the experiment. The evaluated inhibitors BI-3406, trametinib and BKM120 showed synergistic effects in vitro. This combinatorial therapy reduced tumor weight more efficiently in male animals, although the drug concentrations were similar in the tumors of both sexes. These results underline the importance of sex-specific preclinical research and at the same time provide a solid basis for future studies with the tested compounds. [ABSTRACT FROM AUTHOR]

Chemical cross-linking combined withan enzymatic digestion andmass spectrometric analysis of the reaction products has evolved intoan alternative strategy to structurally resolve protein complexes.We investigated conformational changes in peroxisome proliferator-activatedreceptor α (PPARα) upon ligand binding. Using E. colicells with a special tRNA/aminoacyl-tRNA synthetasepair, two PPARα variants were prepared in which Leu-258 or Phe-273were site-specifically replaced by the genetically encoded photoreactiveamino acid p-benzoylphenylalanine (Bpa). PPARα variants were subjected to UV-induced cross-linking,both in the absence and in the presence of ligands. After the photo-cross-linkingreaction, reaction mixtures were enzymatically digested and peptideswere analyzed by mass spectrometry. The inter-residue distances disclosedby the photochemical cross-links served to monitor conformationalchanges in PPARα upon agonist and antagonist binding. The dataobtained with our strategy emphasize the potential of geneticallyencoded internal photo-cross-linkers in combination with mass spectrometryas an alternative method to monitor in-solution3D-proteinstructures. [ABSTRACT FROM AUTHOR]