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Biology subjects

Norberg, E.

Publications and source records attributed to Norberg, E..

2 recordsLinked to original sources

Oncogenic ERK signaling represses chaperone-mediated autophagy through transcriptional control of LAMP-2A

Chaperone-mediated autophagy (CMA) is a selective lysosomal degradation pathway governed by the rate-limiting receptor LAMP-2A and increasingly implicated in cancer. However, the oncogenic circuits that enforce CMA repression and whether this state is therapeutically reversible remain unclear. Here, we developed a quantitative bioluminescence-based reporter to measure CMA activity in human cancer cells and combined parallel chemical and genome-scale CRISPR-Cas9 screens to define regulatory pathways. The chemical screen identified GSK1059615 as a CMA-restoring compound that increased LAMP-2A transcription and protein abundance in vitro and in vivo. In parallel, the CRISPR screen revealed ERK signaling as a pathway-level suppressor of CMA. Genetic or pharmacologic ERK inhibition de-repressed LAMP-2A expression, while integrated modulation of ERK, PI3K-AKT, and p38 signaling coordinated transcriptional induction and stabilization of LAMP-2A. Transcriptomic analyses further implicated FOXO1/FOXP1-driven programs in LAMP-2A regulation. Together, these findings position CMA as an integrated output of oncogenic signaling networks and establish a mechanistic framework for restoring CMA activity in defined cancer contexts.

cell biology↗

The Dietary Supplement Taurine Suppresses Ovarian Cancer Growth

Taurine, a non-proteogenic amino acid, and commonly used nutritional supplement can protect various tissues from degeneration associated with the action of the DNA-damaging chemotherapeutic agent cisplatin. Whether and how taurine protects human ovarian cancer (OC) cells from DNA damage caused by cisplatin is not well understood. We have found that OC ascites-derived cells contained significantly more intracellular taurine than cell cultures modeling OC. In culture, elevation of intracellular taurine concentration to OC ascites-cells-associated levels suppressed proliferation of various OC cell lines and patient-derived organoids, reduced glycolysis, and induced cell protection from cisplatin. Taurine cell protection was associated with decreased DNA damage in response to cisplatin. A combination of RNA sequencing, reverse phase protein arrays, live-cell microscopy, flow cytometry, and biochemical validation experiments provided evidence for taurine-mediated induction of mutant- or wild-type p53 binding to DNA, and activation of p53 effectors involved in negative regulation of the cell cycle (p21), and glycolysis (TIGAR). Paradoxically, taurines suppression of cell proliferation was associated with activation of pro-mitogenic signal transduction including ERK, mTOR, and increased mRNA expression of major DNA damage sensing molecules such as DNAPK, ATM and ATR. While inhibition of ERK or p53 did not interfere with taurines ability to protect cells from cisplatin, suppression of mTOR with Torin2, a clinically relevant inhibitor that also targets DNAPK and ATM/ATR, broke taurines cell protection. Our studies implicate that elevation of intracellular taurine could suppress cell growth, metabolism, and activate cell protective mechanisms involving mTOR and DNA damage sensing signal transduction.

cancer biology↗