Biology subjects

Emmanuel, M.

Publications and source records attributed to Emmanuel, M..

4 recordsLinked to original sources

bioRxiv2025

Invadopodia-Mediated Remodeling of the Lymphatic Endothelium Drives Cancer Cell Lymphatic Dissemination and is Regulated by a CCR7-Vav2-Rac3 Signaling axis.

Cancer cell invasion across a lymphatic endothelial barrier and subsequent colonization of regional lymph nodes often marks the first stage of metastatic dissemination. Lymphatic vessels facilitate the escape of cancer cells and can support further metastatic dissemination. Although the clinical and experimental evidence supports a role for lymph node metastases in promoting metastatic spread, the mechanism employed by cancer cells to navigate a lymphatic endothelium and enter lymphatic vessels is poorly characterized. To investigate this, we assessed the interactions between cancer cells and lymphatic endothelial cells and found that Tks5-positive structures, termed invadopodia, remodel lymphatic endothelial junctions. Loss of Tks5 impaired cancer cell invasion across a lymphatic endothelium and significantly reduced lymph node and lung metastasis in a mouse model of breast cancer progression. Surgical removal of the axillary and brachial lymph nodes prior to orthotopic cancer cell injection resulted in a significant reduction in lung tumor burden, further demonstrating the significance of lymph node metastases to metastatic tumor burden. Next, using breast cancer patient primary tumors we found that elevated expression of CCR7, a chemokine receptor, significantly associated with lymph node metastasis. CCR7 localized to invadopodia and promoted cancer cell invasion across lymphatic endothelium, both in the presence and absence of its canonical ligand CCL19. Tyrosine phosphorylation of CCR7 directed the recruitment of Vav2 and activation of Rac3. Our findings highlight a role for lymphatic metastases in promoting distant metastasis and establish a mechanism by which cancer cells breach a lymphatic endothelium.

cancer biology↗

bioRxiv2025

GABA-GABA_A Receptor Signaling Orchestrates Invasion and Metastasis in Triple Negative Breast Cancer

Cancer is a leading cause of death globally, with the majority of cancer-related deaths resulting from cancer metastasis -the process by which cancer cells disseminate to distant sites. To metastasize, cancer cells acquire traits in support of diverse cellular processes that enable dissemination, survival, and colonization. Tumor cell dissemination requires invasion at local and distant sites and this process can be influenced by intrinsic and extrinsic factors. Here, we investigate the role of the neurotransmitter gamma-aminobutyric acid (GABA) in triple-negative breast cancer (TNBC) invasion and metastasis. TNBC cells increased invasion in response to GABA and this was found to be mediated through the GABAA receptor family. TNBC cell lines were found to be responsive to exogenous GABA and also produced endogenous GABA. Pharmacological inhibition of GABAA receptors reduced TNBC invasion and cancer cell dissemination and resulted in inhibition of GSK3 activity. TNBC cell lines were found to express the GABRE subunit and loss of GABRE impaired GABA-mediated invasion and tumor cell dissemination. These findings support a role for GABA signaling through GABAA receptors in mediating TNBC progression.

cancer biology↗

bioRxiv2025

Exosomes are specialized vehicles to induce fibronectin assembly

Fibronectin is a key stromal matrix molecule whose assembly into fibrils is thought to require cells. In contrast, we find that small exosome-type extracellular vesicles (EVs) are critical initiators of fibronectin assembly. Fibroblasts engineered to be deficient in exosome secretion showed greatly reduced assembly of fibronectin and other stromal matrix molecules in 2D, 3D, and in vivo environments, and led to reduced tumor growth and lung metastasis by breast cancer cells. Furthermore, transgenic mice with defects in exosome secretion had greatly reduced lung fibrosis after treatment with bleomycin. In a direct test of exosome function, we find that the addition of purified small EVs to purified soluble fibronectin in a cell-free system is sufficient to induce fibronectin assembly. The EV-induced fibronectin assembly requires the presence of fibronectin-binding integrins and Syndecan-1 in the EVs. We propose a new model in which secreted exosomes directly drive stromal matrix assembly and tissue fibrosis.

cell biology↗

bioRxiv2024

Effect of phage variation on Shiga toxin 2 (Stx2) production and the virulence of Stx-producing Escherichia coli

Shiga toxin (Stx)-producing Escherichia coli (STEC) causes serious gastrointestinal illness, including hemorrhagic colitis and hemolytic uremic syndrome. Although all known Stxs (Stx1 and Stx2) are encoded by bacteriophages (Stx phages), the production of Stx2 is known to be a major risk factor for severe STEC infections. The production of Stx2, but not Stx1, is tightly coupled with the induction of Stx phages, and Stx2 production levels vary between STEC strains, even within the same serotype. Here, we analyzed the genomic diversity of all Stx phages in 71 strains representing the entire O145:H28 lineage, one of the major STECs. Our analysis revealed the highly dynamic nature of the Stx phages in O145:H28, including the independent acquisition of similar Stx phages by different sublineages and the frequent changes in Stx phages in the same sublineages due to the gain and loss of Stx phages. Analyses of Stx2 production levels in O145:H28 strains and K-12 lysogens of Stx2 phages of specific groups and types, which were defined by their early region sequences and CI repressors, respectively, revealed that short-tailed Stx2a phages (S-Stx2a phages) confer significantly greater Stx2 production to host strains than long-tailed Stx2a phages (L-Stx2a phages). However, L-Stx2a phages that encode a specific type of CI repressor promoted Stx2 production, comparable to the level of production among S-Stx2a phages, as well as promoted virulence to host strains, exceeding the level among other L-Stx2a phages. We also showed a clear link between the phage induction efficiency, which was primarily determined by the early region of each phage, and the level of Stx2 production by host strains. These results provide important insights into the diversification and dynamism of Stx phages and the relationship between the variations in Stx2 phages and the amount of Stx2 production by their host strains. Author summaryShiga toxin (Stx)-producing Escherichia coli (STEC) is an important human intestinal pathogen that causes severe illnesses. These bacteria produce Stx1, Stx2 or both toxins, but the production of Stx2 is an important measure of the virulence of STEC strains. While both types of Stx are encoded by bacteriophages (Stx phages), Stx2 production is tightly coupled with phage induction, and variations in Stx2 phages have been associated with variations in Stx2 production levels by their host O157:H7 STEC strains. However, in non-O157 STEC strains, the variation in Stx phages and its association with host strain production of Stx2 have not yet been fully analyzed. This systematic study of Stx phages in O145:H28 STEC reveals not only the marked genomic diversity and dynamism of Stx phages in this STEC lineage but also that short-tailed Stx2 phages and a specific group of long-tailed Stx2 phages induce high levels of Stx2 production by host strains, and this increased production is linked to the efficient induction of phages.

microbiology↗