Biology subjects

Lassus, P.

Publications and source records attributed to Lassus, P..

5 recordsLinked to original sources

bioRxiv2025

Tumour-derived Ilp8 and Upd3 control intestinal progenitor cells depletion during cachexia in Drosophila larvae

In animals, tumour development triggers systemic effects, impacting the physiology of distant organs. In Drosophila larvae, wing disc neoplastic tumours result in developmental delay and organ wasting reminiscent of cachexia. This paraneoplastic syndrome affects many organs, but its effects on the intestine, a key organ in the regulation of nutrient and energy homeostasis, remain understudied. We describe here that neoplastic tumours also affect the development of the larval midgut, leading to altered cell type numbers, with a depletion of the stem-cell-like Adult Midgut Precursors (AMPs), and a disorganisation of the niche cells which enter precocious differentiation. Importantly, these intestinal cell type alterations are initiated before the onset of reduced food intake, and of muscle and adipose tissue atrophies, and thus represent a new paraneoplastic phenotype. Screening for mediators, we show that tumour derived Ilp8 and Upd3 control AMPs number and niche specification respectively.

developmental biology↗

bioRxiv2023

Fat body glycolysis defects inhibit mTOR and promote distant muscle disorganization through TNF-α/egr and ImpL2 signaling in Drosophila larvae

The fat body in Drosophila larvae serves as a reserve tissue and participates, through its endocrine function, in the regulation of organismal growth and homeostasis. To better understand its role in growth coordination, we induced severe fat body atrophy by knocking down in adipose cells several key enzymes of the glycolytic pathway. Our results show that impairing the last steps of glycolysis led to a drastic shrinkage in adipose cell size and lipid droplets content, and a downregulation of the mTOR pathway. Strikingly, fat body atrophy resulted in the distant disorganization of body wall muscles and the release of muscle-specific proteins in the hemolymph. Molecularly we showed that REPTOR activity was required for fat body atrophy downstream of glycolysis inhibition, and that the effect of fat body atrophy on muscles did not require upd3 secretion, but depended the production of egr/TNF- and of the insulin pathway inhibitor ImpL2.

physiology↗

bioRxiv2020

Paracrine behaviors arbitrate parasite-like interactions between tumor subclones

Explaining the emergence and maintenance of intratumor heterogeneity is an important question in cancer biology. Tumor cells can generate considerable subclonal diversity, which influences tumor growth rate, treatment resistance, and metastasis, yet we know remarkably little about how cells from different subclones interact. Here, we confronted two murine mammary cancer cell lines to determine both the nature and mechanisms of subclonal cellular interactions in vitro. Surprisingly, we found that, compared to monoculture, growth of the winner was enhanced by the presence of the loser cell line, whereas growth of the latter was reduced. Mathematical modeling and laboratory assays indicated that these interactions are mediated by the production of paracrine metabolites resulting in the winner subclone effectively farming the loser. Our findings add a new level of complexity to the mechanisms underlying subclonal growth dynamics.

cancer biology↗

bioRxiv2020

MAGI1 inhibits the AMOTL2/p38 stress pathway and prevents luminal breast tumorigenesis

Alterations to cell polarization or to intercellular junctions are often associated with epithelial cancer progression, including breast cancers (BCa). We show here that the loss of the junctional scaffold protein MAGI1 is associated with bad prognosis in luminal BCa, and promotes tumorigenesis. E-cadherin and the actin binding scaffold AMOTL2 accumulate in MAGI1 deficient cells which are subjected to increased stiffness. These alterations are associated with low YAP activity, the terminal Hippo-pathway effector, but with an elevated ROCK and p38 Stress Activated Protein Kinase activities. Blocking ROCK prevented p38 activation, suggesting that MAGI1 limits p38 activity in part through releasing actin strength. Importantly, the increased tumorigenicity of MAGI1 deficient cells is rescued in the absence of AMOTL2 or after inhibition of p38, demonstrating that MAGI1 acts as a tumor-suppressor in luminal BCa by inhibiting an AMOTL2/p38 stress pathway.

cancer biology↗

bioRxiv2020

Loss of epithelial polarity redirects Notch signaling and triggers a Xrp1 response during neoplastic growth in Drosophila

Aggressive neoplastic growth can be initiated by a limited number of genetic alterations, such as the well-established cooperation between loss of cell architecture and hyperactive signaling pathways. However, our understanding of how these different alterations interact and influence each other remains very incomplete. Using Drosophila paradigms of imaginal wing disc epithelial growth, we have monitored the changes in Notch pathway activity according to the polarity status of cells (scrib mutant). We show that the scrib mutation impacts the direct transcriptional output of the Notch pathway, without altering the global distribution of Su(H), the Notch dedicated transcription factor. The Notch-dependent neoplasms require however, the action of a group of transcription factors, similar to those previously identified for Ras/scrib neoplasm (namely AP-1, Stat92E, Ftz-F1, and bZIP factors), further suggesting the importance of this transcription factor network during neoplastic growth. Finally our work highlights some Notch/scrib specificities, in particular the role of the PAR domain containing bZIP transcription factor and Notch direct target Pdp1 for neoplastic growth.

developmental biology↗