Soto-Gamez, A. | Search bioRxiv

bioRxiv2024

Notch Signaling Drives Pro-Regenerative and Migratory Traits in Glandular Stem/Progenitor Cells

Organoid models have advanced our understanding of adult stem/progenitor cell dynamics and function. However, uncovering the regulatory mechanisms of scarce and often quiescent stem cells in organs like the salivary glands remains challenging. Using single-cell RNA sequencing and bulk ATAC and RNA-sequencing analysis, we conducted in-depth profiling of the cellular populations and key signaling pathways characterizing a mouse submandibular salivary gland organoid (mSGO) model at different temporal stages and in response to radiation damage. We identified Sox9- and Itgb1-expressing cells as the most primitive adult stem/progenitor populations and uncover novel stemness and migratory roles for Cd44-expressing cells. Moreover, we revealed that Notch signaling is essential for maintaining self-renewal and migration potential of these stem/progenitor cells post-irradiation. Extending these findings to patient-derived mSGOs, as well as murine and patient-derived mammary and thyroid gland organoids, we confirmed Notch signaling as a conserved regulator of stem/progenitor cell function under migrative and regenerative conditions.

cell biology↗

bioRxiv2024

CDK4/6 inhibitors promote senescence-associated lysosomal alterations and enhance sensitivity to lysosomotropic agents in breast cancer

Breast cancer is a leading cause of mortality worldwide. Pharmacological inhibitors of Cyclin- Dependent Kinases (CDK) 4 and 6 (CDK4/6i) inhibit breast cancer growth by inducing a senescent-like state. However, the long-term treatment efficacy remains hindered by the development of drug resistance. Clearance of senescent-like cancer cells may extend the durability of treatment. In this study, we showed that CDK4/6i-treated breast cancer cells exhibit various senescence-associated phenotypes, but remain insensitive to common senolytic compounds. By searching for novel vulnerabilities, we identified a significantly increased lysosomal mass and altered lysosomal structure across various breast cancer cell types upon exposure to CDK4/6i in preclinical systems and clinical specimens. We demonstrated that these lysosomal alterations render breast cancer cells sensitive to lysosomotropic agents, such as L- leucyl-L-leucine methyl ester (LLOMe) and salinomycin. Importantly, sequential treatment with CDK4/6i/lysosomotropic agents effectively reduced the growth of both Hormone Receptor- positive (HR+) and triple-negative breast cancer (TNBC) cells in vivo. This sequential therapeutic strategy offers a promising approach to eliminate CDK4/6i-induced senescent(-like) cells, potentially reducing tumor recurrence and enhancing the overall efficacy of breast cancer therapy.

cancer biology↗