Berneburg, M. | Search bioRxiv

bioRxiv2024

Metastasis founder cells activate immunosuppression early in human melanoma metastatic colonization

The earliest steps of lethal metastasis in patients are incompletely understood. To dissect them, we prospectively searched for the earliest detectable disseminated cancer cells (DCC) in sentinel lymph node biopsies of 492 stage I-III patients. By visually-controlled, micromanipulator-assisted isolation and single cell transcriptome analysis of these extremely rare DCC, we identified MCSP+ melanoma cells as strong candidates for metastasis founder cells (MFC) in lymph nodes. Based on a median follow-up time of 6 years, their detection was the strongest predictor of systemic metastasis and death upon multivariable analysis. During transition from single cells to metastasis-initiating clusters, melanoma DCC were exposed to CD8 T cell attack, activated the extracellular vesicular exosomal pathway, and expressed the immunomodulatory proteins CD155 and CD276, but rarely PD-L1. CD155 and CD276-positive extracellular vesicles from patient-derived DCC models exhibited an immunosuppressive activity on CD8 T cells. Our data indicate that either direct targeting of MFC employing MCSP or their immune escape mechanisms might be key for cure of early-stage melanoma.

cancer biology↗

bioRxiv2021

Induced neural progenitor cells and iPS-neurons from major depressive disorder patients show altered bioenergetics and electrophysiological properties

The molecular pathomechanisms of major depressive disorder (MDD) are still not completely understood. Here, we follow the hypothesis, that mitochondria dysfunction which is inevitably associated with bioenergetic disbalance is a risk factor that contributes to the susceptibility of an individual to develop MDD. Thus, we investigated molecular mechanisms related to mitochondrial function in induced neuronal progenitor cells (NPCs) which were reprogrammed from fibroblasts of eight MDD patients and eight non-depressed controls. We found significantly lower maximal respiration rates, altered cytosolic basal calcium levels, and smaller soma size in NPCs derived from MDD patients. These findings are partially consistent with our earlier observations in MDD patient-derived fibroblasts. Furthermore, we differentiated MDD and control NPCs into iPS-neurons and analysed their passive biophysical and active electrophysiological properties to investigate whether neuronal function can be related to altered mitochondrial activity and bioenergetics. Interestingly, MDD patient-derived iPS-neurons showed significantly lower membrane capacitance, a less hyperpolarized membrane potential, increased Na+ current density and increased spontaneous electrical activity. Our findings indicate that functional differences evident in fibroblasts derived from MDD patients are partially present after reprogramming to induced-NPCs, might relate to altered function of iPS-neurons and thus might be associated with the aetiology of major depressive disorder.

neuroscience↗