Metastatic melanoma is hallmarked by its ability of phenotype switching to more slowly proliferating, but highly invasive cells. Here, we tested the impact of signal transducer and activator of transcription 3 (STAT3) on melanoma progression in association with melanocyte inducing transcription factor (MITF) expression levels. We established a mouse melanoma model for deleting Stat3 in melanocytes with specific expression of human hyperactive NRAS Q61K in an Ink4a deficient background, two frequent driver mutations in human melanoma. Mice devoid of Stat3 showed early disease onset with higher proliferation in primary tumors, but displayed significantly diminished lung, brain and liver metastases. Whole genome expression profiling of tumor-derived cells also showed a reduced invasion phenotype, which was further corroborated by 3D melanoma model analysis. Notably, loss or knockdown of STAT3 in mouse or human cells resulted in up-regulation of MITF and induction of cell proliferation. Mechanistically we show that STAT3-induced CEBPa/b expression was sufficient to suppress MITF transcription. Epigenetic analysis by ATAC-seq confirmed that CEBPa/b binding to the MITF enhancer region silenced the MITF locus. Finally, by classification of patient-derived melanoma samples, we show that STAT3 and MITF act antagonistically and hence contribute differentially to melanoma progression. We conclude that STAT3 is a driver of the metastatic process in melanoma and able to antagonize MITF via direct induction of CEBP family member transcription.

Extracellular vesicles (EVs) are nanosized lipid bilayer-encapsulated particles secreted by virtually all cell types. EVs play an essential role in cellular crosstalk in health and disease. The cellular origin of EVs determines their composition and potential therapeutic effect. Mesenchymal stem/stromal cell (MSC)-derived EVs have shown a comparable therapeutic potential to their donor cells, making them a promising tool for regenerative medicine. The therapeutic application of EVs circumvents some safety concerns associated with the transplantation of viable, replicating cells and facilitates the quality-controlled production as a ready-to-go, off-the-shelf biological therapy. Recently, the International Society for Extracellular Vesicles (ISEV) suggested a set of minimal biochemical, biophysical and functional standards to define extracellular vesicles and their functions to improve standardisation in EV research. However, nonstandardised EV isolation methods and the limited availability of cross-reacting markers for most animal species restrict the application of these standards in the veterinary field and, therefore, the species comparability and standardisation of animal experiments. In this study, EVs were isolated from equine bone-marrow-derived MSCs using two different isolation methods, stepwise ultracentrifugation and size exclusion chromatography, and minimal experimental requirements for equine EVs were established and validated. Equine EVs were characterised using a nanotracking analysis, fluorescence-triggered flow cytometry, Western blot and transelectron microscopy. Based on the ISEV standards, minimal criteria for defining equine EVs are suggested as a baseline to allow the comparison of EV preparations obtained by different laboratories.

Tendinopathy, a prevalent overuse injury, lacks effective treatment options, leading to a significant impact on quality of life and socioeconomic burden. Mesenchymal stem/stromal cells (MSCs) and their secretome, including conditioned medium (CM) and extracellular vesicles (EVs), have shown promise in tissue regeneration and immunomodulation. However, it remains unclear which components of the secretome contribute to their therapeutic effects. This study aimed to compare the efficacy of CM, EVs, and the soluble protein fraction (PF) in treating inflamed tenocytes. CM exhibited the highest protein and particle concentrations, followed by PF and EVs. Inflammation significantly altered gene expression in tenocytes, with CM showing the most distinct separation from the inflamed control group. Treatment with CM resulted in the most significant differential gene expression, with both upregulated and downregulated genes related to inflammation and tissue regeneration. EV treatment also demonstrated a therapeutic effect, albeit to a lesser extent. These findings suggest that CM holds superior therapeutic efficacy compared with its EV fraction alone, emphasizing the importance of the complete secretome in tendon injury treatment.

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FACTORS INFLUENCINGport inferred that muscle fasciculations result from a direct action of the blood on the muscle fibers, Under the condi tilons of these experiments, it is evident that the fasciculations and tonic spasms occasioned by alkalosis and hypocalcemia can occur as the result of spontaneous iterative discharges arising in peripheral motor nerve fibers or their terminations in the motor end plates. These results cannot, of course, preclude the possibility of the participation of neurons within the central nervous system, or of sensory neurons in spinal and perhaps even supraspinal reflex arcs. In fact, there is considerable evidence that sensory fibers also are irritated and discharge repetitively in human tetany ( 2 ) . However, our results strongly suggest that activation of peripheral motor nerve fibers or terminations account for the motor manifestations of tetany whether caused by an elevation in blood pH or a reduction in ionized blood calcium. This view is supported by Kugelberg's( 15) finding in one human subject with inveterate hypocalcemic tetany that impulses occurring in the fourth interosseous muscle of the hand and recorded electromyographically continued unaltered after apparently effective procaine block of the ulnar nerve at the elbow.Sumnaar.v. 1. Tetany was produced acutely in eleven cats and one dog with solutions of sodium bicarbonate, sodium carbonate and a phosphate buffer administered by venoclysis. Fasciculations and tonic spasms involving especially the head and forelimb musculature characterized this form of tetany. Clonic spasiiis were were not seen in anesthetized ani-SHAY RAT VLCERATION 333 mals. 2. Section of the hypoglossal nerve did not significantly influence the fasciculations oi the tongue musculature. Section oi the brachial plexus did not significantly inhence the fasciculations or tonic spasms of the iorelimb musculature. 3. Paralvtic doses of dtubocurarine blocked all motor maniiestations of tetany. 4. It was concluded that all of the motor phenomena characterizing alkalotic and hypocalcemic tetany could result from the spontaneous iterative discharges occurring in peripheral motor nerye fibers or their terminations.In our experience, the incidence of ulcers paper. Recently, Madden ef QZ. ( 1) in a critiin the Shay rat varied from 100% to 25%. cal study of the Shay procedure concluded There are no apparent reasons for this varia-that the method is valuable for the study oi tion, and some of the complicating, but sig-gastric secretion and of less value ior the study nificant, observations are recorded in this of the ulceration mechanism. We have used

IN 1917, at a time when the existence of the various hormones of the pituitary was not established and none had been isolated, one of us (C. F.) advanced a working hypothesis on the relationship of this gland and neoplastic disease. The necessity for further research into the effect of the pituitary gland (anterior lobe) on cancer was pointed out. At the time it was known that adenomas of this gland produced abnormalities in children and young adults; it was therefore postulated that in later life, when gigantism and acromegaly were no longer possible, increased activity of the pituitary gland might be responsible for the production of tumours (Funk, 1917). For a long time and for obvious reasons it was impossible to put this hypothesis to a test. Thanks to the classical work of Evans, Li and Simpson (1948) we now have the necessary tools for preliminary and systematic appraisal of the importance of various hormones of the anterior pituitary in tumour growth.The purpose of the work reported in this paper was to test the effect of various anterior pituitary and related hormones upon the growth of implanted tumours in hypophysectomized rats. As a supplement to this work we also dealt with the removal of certain organs (mainly glands of internal secretion) on the rate of growth of a transplanted rat tumour in otherwise intact animals. While there is no doubt that studies on this subject have already been made, it appears doubtful whether a systematic study was ever made of the effect of the removal of these organs upon the growth of one particular tumour. As an addendum we have also investigated the influence of alloxan diabetes upon the tumour. MATERIALS AND METHODS.Hypophysectomy experiments.The hypophysectomized and normal rats, Sprague-Dawley strain, were supplied to us via air freight by the Hormone Assay Laboratories, Inc., Chicago, Illinois. The tumour used was the Walker Carcinosarcoma 256. As a criterion of completeness of hypophysectomy we have used the test established by CortisJones, Crooke, Henley, Morris and Morris (1950), and have eliminated from our experiments those rats not receiving gonadotropin whose testes weighed over 500 mg. In order to ascertain the relative purities of the hormones used in this investigation the following organs were excised and weighed: the thyroids, the adrenals, the testes and the spleen.The animals were divided into groups after tumour implantation, which

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The amount of aspirin required to ameliorate the glycosuria of the rat is very large. and there is no reason to expect that this drug would be of any therapeutic value in clinical diabetes.Aspirin ~7 a s administered to 7 mildl!. diabetic rats which were force-fed a medium carbohydrate diet. The dose was 30. 80. and 160 mg of the drug per day. A marked amelioration of the glycosuria together with a gain in weight was noted in each rat. U-hen the drug was withdrawn, there was exacerbation of the glycosuria to significantly higher levels than were noted during the preinjection period, and there was an accompanj.ing loss of weight.Sumttzary. C roc ke r S a r c on1 a N 0..4ddenduin. Since this manuscript was submitted for publication a review (Gross, 31. and L. A. Greenberg, Hillhouse Press, Kew Haven, Conn., 1948. pp 108-9) of the effects of salicylates upon carbohydrate metabolism has been noted. Salicylates were shown to have an ameliorating effect upon diabetes mellitus in man as early as 1875, but large and frequently toxic amounts were required and the use of salicylates for this purpose has long since been discontinued. The nature of the action of salicylates upon carbohydrate metabolism remains as an interesting problem.