Biology subjects

Scherzer, M. T.

Publications and source records attributed to Scherzer, M. T..

5 recordsLinked to original sources

bioRxiv2025

BRAFV600E-Driven Lung Tumorigenesis Requires Ligand-Mediated Activation of ERBB Receptor Signaling

Secretion of ligands of the human epidermal growth factor (EGFR) family of receptors or erythroblastic leukemia viral oncogene family (ERBB1-4) is a feature common to many cancer cells. However, our understanding of the role of autocrine ligands in the aberrant behavior of cancer remains incomplete. Here we demonstrate that, in numerous preclinical models of lung tumorigenesis, BRAFV600E signaling promotes expression of ligands including HB-EGF, TGF, Epi- and Amphiregulin. Moreover, using both genetic or pharmacological approaches, we demonstrate that ligand-mediated activation of EGFR signaling in the tumor cell is required to sustain both early-stage BRAFV600E-driven lung tumorigenesis and supports late-stage BRAFV600E-driven lung cancer maintenance. Unbiased Reverse Phase Protein Analyses (RPPA) analyses, paired with targeted validation, reveals ERBB signaling serves to sustain signaling through the ERK1/2 MAP kinase pathway, through effects on ARAF and CRAF, and on the parallel JUN kinase (JNK) pathway. Furthermore, EGFR is activated in a cohort of BRAF-mutated lung cancer patients both pre- and post-treatment. Finally, we noted significant improvement in the depth and durability of therapeutic responses in preclinical models of BRAFV600E-driven lung cancer by combined inhibition of both BRAFV600E signaling plus pan-ERBB signaling. Collectively, this work provides evidence for an important role for ERBB family signaling in the genesis and maintenance of BRAFV600E-driven lung cancers, and the potential for future therapeutic improvement by rational combination targeting of these pathways. SIGNIFICANCEBRAFT1799A serves as a predictive biomarker for FDA-approved targeted inhibition of BRAFV600E oncoprotein kinase signaling in non-small cell lung cancer (NSCLC). However the occurrence of primary or acquired drug resistance limit the depth and durability of patient responses. Studies described here provide a mechanistic rationale for clinical testing of first-line BRAFV600E inhibition combined with pan-ERBB inhibition to improve the depth and durability of initial patient responses, and delay the emergence of lethal drug resistant disease.

cancer biology↗

bioRxiv2025

Rare codon translation regulates growth factor-dependent cell proliferation

In animal cells, growth factor signaling promotes both cell cycle progression and cell growth, but the connection between these two processes is not well understood. Here, we investigated whether cell cycling and cell growth are coupled through protein translation. Using ribosome profiling and mRNA sequencing we examined changes in translational activities in human Retinal Pigment Epithelial (RPE-1) cells as they entered the cell cycle in response to serum growth factor stimulation. We found that, in addition to mRNAs encoding factors in ribosome biogenesis and translational initiation, mRNAs encoding many DNA replication factors were translationally upregulated by serum. We also noted increases of snoRNAs and tRNAs, which facilitate translation. By analyzing the distribution of 21nt mRNA ribosome footprints, produced by stalled ribosomes that lack amino-acyl-tRNAs, we found that growth factor withdrawal promoted ribosome stalling preferentially at specific rare codons. DNA replication factor genes that were translationally upregulated by serum and essential for cell cycle progression were enriched in many of these rare codons, and the cognate tRNAs that read these codons were induced by growth signaling. The serum-dependent induction of translation was more mTOR-dependent than MEK-dependent. Our results support a novel regulatory mechanism wherein growth factor signaling promotes cell proliferation by inducing tRNAs that decode rare codons, which in turn promote translational elongation of mRNAs encoding DNA replication factors to accelerate G1/S progression. Significance StatementWe present a mechanistic explanation for the longstanding question of how cell cycle progression is coupled to cell growth. Our findings emphasize the role of translation machinery and reveal a "growth checkpoint" that ensures that DNA replication gene translation occurs only when growth signaling has activated the protein translation machinery. Our work complements the textbook model of the Growth Factor-Cyclin D-Rb-E2F transcriptional mechanism for cell cycle entry and is a fundamental advance for the fields of cell proliferation and growth factor signaling.

cell biology↗

bioRxiv2024

Transdermal Delivery of Ultradeformable Cationic Liposomes Complexed with miR211-5p (UCL-211) Stabilizes BRAFV600E+ Melanocytic Nevi

Small non-coding RNAs (e.g. siRNA, miRNA) are involved in a variety of melanocyte-associated skin conditions and act as drivers for alterations in gene expression within melanocytes. These molecular changes can potentially affect the cellular stability of melanocytes and promote their oncogenic transformation. Thus, small RNAs can be considered as therapeutic targets for these conditions, however, their topical delivery to the melanocytes through the epidermal barrier is challenging. We synthesized and extensively evaluated ultradeformable cationic liposome (UCLs) carriers complexed with synthetic microRNAs (miR211-5p; UCL-211) for transdermal delivery to melanocytes. UCL-211 complexes were characterized for their physicochemical properties, encapsulation efficiency, and deformability, which revealed a significant advantage over conventional liposomal carriers. Increased expression of miR211-5p stabilizes melanocytic nevi and keeps them in growth-arrested state. We did a comprehensive assessment of cellular delivery, and biological activity of the miR211-5p carried by UCL-211 in vitro and their permeation through the epidermis of intact skin using ex vivo human skin tissue explants. We also demonstrated, in vivo, that topical delivery of miR211-5p by UCL-211 stabilized BRAFV600E+ nevi melanocytes in a benign nevi state.

pharmacology and toxicology↗

bioRxiv2024

Inhibition of ULK1/2 and KRASG12C controls tumor growth in preclinical models of lung cancer

Mutational activation of KRAS occurs commonly in lung carcinogenesis and, with the recent FDA approval of covalent inhibitors of KRASG12C such as sotorasib or adagrasib, KRAS oncoproteins are important pharmacological targets in non-small cell lung cancer (NSCLC). However, not all KRASG12C-driven NSCLCs respond to these inhibitors, and the emergence of drug resistance in those patients that do respond can be rapid and pleiotropic. Hence, based on a backbone of covalent inhibition of KRASG12C, efforts are underway to develop effective combination therapies. Here we report that inhibition of KRASG12C signaling increases autophagy in KRASG12C expressing lung cancer cells. Moreover, the combination of DCC-3116, a selective ULK1/2 inhibitor, plus sotorasib displays cooperative/synergistic suppression of human KRASG12C-driven lung cancer cell proliferation in vitro and superior tumor control in vivo. Additionally, in genetically engineered mouse models of KRASG12C-driven NSCLC, inhibition of either KRASG12C or ULK1/2 decreases tumor burden and increases mouse survival. Consequently, these data suggest that ULK1/2-mediated autophagy is a pharmacologically actionable cytoprotective stress response to inhibition of KRASG12C in lung cancer.

cancer biology↗

bioRxiv2022

"Transposon Mutagenesis Reveals RBMS3 as a Promoter of Malignant Progression of BRAFV600E-Driven Lung Tumorigenesis."

Mutationally-activated BRAFV600E is detected in ~2% of all human non-small cell lung cancers (NSCLC), and serves as a predictive biomarker for treatment of patients with FDA-approved pathway-targeted therapies that inhibit signaling by the BRAFV600E oncoprotein kinase. In genetically engineered mouse (GEM) models, expression of BRAFV600E in alveolar type 2 (AT2) pneumocytes initiates the development of benign lung tumors that, without additional genetic alterations, rarely progress to malignant lung adenocarcinomas. To identify genes that might cooperate with BRAFV600E for malignant lung cancer progression we employed Sleeping Beauty (SB)-mediated transposon mutagenesis, which dramatically accelerated the onset of lethal lung adenocarcinomas. Amongst the diverse group of genes identified by this in vivo screen was Rbms3 (RNA binding motif single-stranded interacting protein 3), an RNA-binding protein implicated as a possible tumor suppressor. Using CRISPR/CAS9 gene editing we confirmed that RBMS3 silencing cooperated with BRAFV600E to promote progression of malignant lung cancer with a distinct micropapillary architecture. Moreover, RBMS3 silencing also cooperated with BRAFV600E to promote the growth of lung organoids in vitro. BRAFV600E/RBMS3Null lung tumors displayed elevated expression of b-catenin (CTNNB1), suggesting that RBMS3 silencing may result in elevated signaling through the WNT>CTNNB1>c-MYC pathway. Finally, analyses of patient samples in The Cancer Genome Atlas (TCGA) revealed that the region of chromosome 3 encompassing RBMS3 is frequently lost in NSCLC and correlates with poor patient prognosis. Collectively, SB-mediated transposon mutagenesis has revealed the ability of a novel tumor suppressor, RBMS3, to cooperate with BRAFV600E to promote lung carcinogenesis, and suggests that RBMS3 silencing may contribute to malignant progression of numerous human lung cancers. SIGNIFICANCEThe BRAFV600E oncoprotein kinase is a potent initiator of benign lung tumorigenesis, but is insufficient to elicit malignant lung adenocarcinoma without additional cooperating alterations. Sleeping Beauty-mediated transposon mutagenesis has revealed a number of genes that cooperate with BRAFV600E to promote lung cancer progression, in particular Rbms3, which encodes an RNA binding protein. Hence, this genetic screen provides a deeper understanding of the molecular mechanisms underlying BRAFV600E-driven lung carcinogenesis, and is an important step improving our ability to successfully target this disease.

cancer biology↗