Biology subjects

Lengner, C.

Publications and source records attributed to Lengner, C..

7 recordsLinked to original sources

bioRxiv2025

Single-Cell RNA Sequencing and Inferred Protein Activity Analysis Reveal a Distinct Tumor Phenotype in Early-Onset Colorectal Cancer Patients

Colorectal cancer (CRC) diagnosed before age 50 years (early-onset CRC, EO-CRC) is rising at an alarming rate, yet its molecular and microenvironmental drivers remain poorly understood. EO-CRC is highly heterogeneous, and while subtle differences from late-onset CRC (LO-CRC) have been reported, their full extent remains unresolved due to the limited scope of previous studies. Here, we integrate public data with in-house clinical samples profiled by single-cell RNA sequencing (scRNA-seq) and multiplex immunofluorescence (mIF) to compare EO-CRC and LO-CRC. Additionally, we employ gene regulatory network-based protein activity inference (VIPER), enabling a more precise characterization of key regulatory proteins driving tumor-stroma interactions. Our analysis reveals that EO-CRC and LO-CRC have a largely similar immune composition, challenging previous reports of an "immune-cold" phenotype in EO-CRC. However, we identify distinct stromal differences, including a significant enrichment of fibroblasts in EO-CRC. Notably, we define a previously unrecognized epithelial subpopulation in EO-CRC, marked by high expression of toll-like receptor 4 (TLR4) and C-C chemokine receptor type 5 (CCR5)--key mediators of inflammation-driven tumor progression and fibroblast recruitment. These findings suggest that EO-CRC may be driven by a tumor-intrinsic inflammatory phenotype with enhanced stromagenesis, providing new insights into potential mechanisms underlying its increasing incidence in young adults.

cancer biology↗

bioRxiv2024

APC coordinates GSK3 phosphorylation of SETD8 to suppress colorectal cancer

Colorectal cancer (CRC) is the second-leading cause of cancer-related deaths with increasing incidence globally. Mutations in the tumor suppressor APC initiate CRC at least in part by preventing the GSK3 kinase from phosphorylating {beta}-CATENIN, leading to its constitutive stabilization and transactivation of mitogenic target genes. While the importance of {beta}-CATENIN phosphorylation by GSK3 is well-established, APC regulation of GSK3 activity upon other targets with potential oncogenic relevance are not understood. Here, we identify the H4K20 methyltransferase SETD8 as target of APC-coordinated GSK3 phosphorylation in the intestinal epithelium. We found that phosphorylation by GSK3 restrains the oncogenic activity of SETD8, with loss of phosphorylation sensitizing mice to oncogenic insults. Mechanistically, phosphorylation alters the role of SETD8 in transcriptional regulation, most notably by preventing it from activating oncogenic YAP signaling and a fetal-like transcriptional program. These results underscore the importance of SETD8 in CRC and represent a novel {beta}-CATENIN -independent oncogenic consequence of APC loss. SignificanceGSK3 is thought to restrain colorectal cancer primarily by phosphorylation of {beta}-CATENIN. We show that GSK3 also phosphorylates SETD8, preventing SETD8 activation of oncogenic programs including YAP-driven fetal-like gene expression.

cancer biology↗

bioRxiv2024

Sox9 marks limbal stem cells and is required for asymmetric cell fate switch in the corneal epithelium

Adult tissues with high cellular turnover require a balance between stem cell renewal and differentiation, yet the mechanisms underlying this equilibrium are unclear. The cornea exhibits a polarized lateral flow of progenitors from the peripheral stem cell niche to the center; attributed to differences in cellular fate. To identify genes that are critical for regulating the asymmetric fates of limbal stem cells and their transient amplified progeny in the central cornea, we utilized an in vivo cell cycle reporter to isolate proliferating basal cells across the anterior ocular surface epithelium and performed single-cell transcriptional analysis. This strategy greatly increased the resolution and revealed distinct basal cell identities with unique expression profiles of structural genes and transcription factors. We focused on Sox9; a transcription factor implicated in stem cell regulation across various organs. Sox9 was found to be differentially expressed between limbal stem cells and their progeny in the central corneal. Lineage tracing analysis confirmed that Sox9 marks long-lived limbal stem cells and conditional deletion led to abnormal differentiation and squamous metaplasia in the central cornea. These data suggest a requirement for Sox9 for the switch to asymmetric fate and commitment toward differentiation, as transient cells exit the limbal niche. By inhibiting terminal differentiation of corneal progenitors and forcing them into perpetual symmetric divisions, we replicated the Sox9 loss-of-function phenotype. Our findings reveal an essential role for Sox9 for the spatial regulation of asymmetric fate in the corneal epithelium that is required to sustain tissue homeostasis.

developmental biology↗

bioRxiv2023

Musashi-2 (MSI2) regulation of DNA damage response in lung cancer

Lung cancer is one of the most common types of cancers worldwide. Non-small cell lung cancer (NSCLC), typically caused by KRAS and TP53 driver mutations, represents the majority of all new lung cancer diagnoses. Overexpression of the RNA-binding protein (RBP) Musashi-2 (MSI2) has been associated with NSCLC progression. To investigate the role of MSI2 in NSCLC development, we compared the tumorigenesis in mice with lung-specific Kras-activating mutation and Trp53 deletion, with and without Msi2 deletion (KP versus KPM2 mice). KPM2 mice showed decreased lung tumorigenesis in comparison with KP mice what supports published data. In addition, using cell lines from KP and KPM2 tumors, and human NSCLC cell lines, we found that MSI2 directly binds ATM/Atm mRNA and regulates its translation. MSI2 depletion impaired DNA damage response (DDR) signaling and sensitized human and murine NSCLC cells to treatment with PARP inhibitors in vitro and in vivo. Taken together, we conclude that MSI2 supports lung tumorigenesis, in part, by direct positive regulation of ATM protein expression and DDR. This adds the knowledge of MSI2 function in lung cancer development. Targeting MSI2 may be a promising strategy to treat lung cancer. SignificanceThis study shows the novel role of Musashi-2 as regulator of ATM expression and DDR in lung cancer.

cancer biology↗

bioRxiv2022

APC and P53 mutations synergize to create a therapeutic vulnerability to NOTUM inhibition in advanced colorectal cancer

Colorectal cancer (CRC) is a leading cause of cancer-related deaths globally, with the majority of cases initiated by inactivation of the APC tumor suppressor. This results in the constitutive transcriptional activation of the canonical WNT signal transduction pathway effector {beta}-Catenin, along with induction of WNT feedback inhibitors, including the extracellular palmitoleoyl-protein carboxylesterase NOTUM. Here, we show that NOTUM retains cell-autonomous tumor suppressive activity in APC-null adenomatous lesions despite constitutive {beta}-Catenin activation. Strikingly, we find that NOTUM becomes an obligate oncogene upon subsequent P53 inactivation during the adenoma-adenocarcinoma transition, and that these phenotypes are WNT-independent, resulting from differential activity of NOTUM upon its enzymatic targets Glypican 1 and 4 in early vs. late-stage disease, respectively. Ultimately, preclinical mouse models of CRC and human tumoroid cultures demonstrate that pharmacological inhibition of NOTUM is highly effective in arresting primary adenocarcinoma growth and inhibiting metastatic colonization of distal organs. The finding that a single agent targeting an extracellular enzyme is effective in treating highly aggressive tumors make NOTUM a novel therapeutic vulnerability in advanced colorectal adenocarcinomas.

cancer biology↗

bioRxiv2020

Dissecting phenotypic transitions in metastatic disease via photoconversion-based isolation

Cancer patients presenting with surgically resectable disease often harbor occult metastases, a potential source of relapse that is targetable only through systemic therapy. Studies of this occult fraction have been limited by a lack of tools with which to isolate discrete cells based on spatial grounds. We developed PIC-IT, photoconversion-based isolation technique allowing efficient recovery of cell clusters of any size including solitary disseminated tumor cells (DTCs), which are largely inaccessible otherwise. In a murine pancreatic cancer model, transcriptional profiling of spontaneously arising DTCs revealed phenotypic heterogeneity, functionally reduced propensity to proliferate and enrichment for inflammatory-response phenotype associated with NF-{kappa}B /AP-1 signaling. Pharmacological inhibition of NF-{kappa}B depleted DTCs but had no effect on macrometastases, suggesting DTCs are particularly dependent on this pathway. PIC-IT enables systematic investigation of the earliest stages of metastatic colonization. Moreover, this new technique can be applied to other biological systems in which isolation and characterization of spatially distinct cell populations is not currently feasible.

cancer biology↗

bioRxiv2019

Rapidly cycling stem cells regenerate the intestine independent of Lgr5high cells

The +4 cells in intestinal crypts are DNA damage-resistant and contribute to regeneration. However, their exact identity and the mechanism underlying +4 cell-mediated regeneration remain unclear. Using lineage tracing, we show that cells marked by an Msi1 reporter (Msi1+) are enriched at the +4 position in intestinal crypts and exhibit DNA damage resistance. Single-cell RNA sequencing reveals that the Msi1+ cells are heterogeneous with the majority being intestinal stem cells (ISCs). The DNA damage-resistant subpopulation of Msi1+ cells is characterized by low-to-negative Lgr5 expression and is more rapidly cycling than Lgr5high radio-sensitive crypt base columnar stem cells (CBCs); they enable fast repopulation of the intestinal epithelium independent of CBCs that are largely depleted after irradiation. Furthermore, relative to CBCs, Msi1+ cells preferentially produce Paneth cells during homeostasis and upon radiation repair. Together, we demonstrate that the DNA damage-resistant Msi1+ cells are rapidly cycling ISCs that maintain and regenerate the intestinal epithelium.

cell biology↗