Search bioRxiv⌕ Search

Biology subjects

Wen, K. W.

Publications and source records attributed to Wen, K. W..

4 recordsLinked to original sources

Identification of TM4SF1 as a novel tumor-associated antigen in biliary tract cancers targetable by CAR-T cell therapy

Background & Aims: Biliary tract cancers (BTCs) are a rare set of genetically heterogenous and aggressive malignancies associated with delayed presentation and poor prognosis. Thus, there is an unmet clinical need for the development of novel therapeutic strategies. Identification of uniquely expressed cell-surface, tumor-associated antigens (TAAs) holds promise in epithelial tumors more generally, as they can serve as ligands for a variety of therapeutics, including CAR-T cell therapy. However, TAA identification in BTCs has been limited by expression in normal liver tissue. Here, we aim to characterize the cell-surface protein transmembrane 4 L six family member 1 (TM4SF1) as a potential BTC TAA targetable by CAR-T therapy. Methods: TM4SF1 expression in BTC relative to normal hepatic/biliary tissue was characterized at the mRNA level by analyzing TCGA datasets and at the protein level by immunohistochemistry of archival primary BTC tissue. Anti-TM4SF1 CAR-T cells were evaluated through in vitro coculture assays against human-derived BTC cell lines and in a cell line-derived xenograft (CDX) model. Results: We find TM4SF1 is significantly upregulated in BTC relative to normal hepatic/biliary tissue and across BTC anatomical subtypes at the mRNA and protein level. To validate TM4SF1 as a targetable TAA in BTC, we show anti-TM4SF1 CAR-T cells demonstrate robust growth inhibition of BTC cell lines in vitro and significant anti-tumor activity against a CDX in vivo. Conclusions: Together, our data provides support for TM4SF1 as a promising TAA in BTCs that can be used for the rational development of targeted therapeutic modalities, including CAR-T cells, in a patient population with significant unmet need.

cancer biology↗

PCSK9 dependent cholesterol acquisition and utilization underlies metastatic organ preference in pancreatic cancer.

To grow at distant sites, metastatic cells must overcome major challenges posed by the unique cellular and metabolic composition of secondary organs1. Pancreatic ductal adenocarcinoma (PDAC) is an aggressive disease that metastasizes to the liver and lungs. Despite evidence of metabolic reprogramming away from the primary site, the key drivers that dictate the ability of PDAC cells to colonize the liver or lungs and survive there are undefined. We identified Proprotein Convertase Subtilisin/Kexin Type 9 (PCSK9) as predictive of colonization of the liver versus lungs by integrating datasets describing the metastatic tropism of human PDAC cell lines2, with in vivo metastasis modeling in mice and gene expression correlation analysis. PCSK9 is a negative regulator of low density lipoprotein(LDL)-cholesterol import and, accordingly, PCSK9-low PDAC cells exhibit strong preference for colonizing LDL-rich liver tissue. Cholesterol taken up by liveravid PCSK9-low cells is converted into the signaling oxysterol, 24(S)-hydroxycholesterol, which reprograms the surrounding microenvironment to induce nutrient release from neighboring hepatocytes. Conversely, PCSK9-high, lung-avid PDAC cells rely on transcriptional upregulation of the distal cholesterol synthesis pathway to generate intermediates, chiefly, 7dehydrodesmosterol and 7-dehydrocholesterol, with protective action against ferroptosis, a vulnerability in the oxygen-rich microenvironment of the lung. Increasing PCSK9 levels redirected liver-avid cells to the lung whereas its ablation drove lung-avid cells to the liver, thereby establishing PCSK9 as necessary and sufficient for secondary organ site preference. Our studies reveal PCSK9-driven differential utilization of the distal cholesterol synthesis pathway as a key and potentially actionable driver of metastatic growth in PDAC.

cancer biology↗

Functional screen for mediators of onco-mRNA translation specificity

Oncogenic protein dosage is tightly regulated to enable cancer cells to adapt and survive. Whether this is regulated at the level of translational control and the key factors in cis and trans remain unknown. The Myc oncogene is a central paradigm of an exquisitely regulated oncogene and a major driver of pancreatic ductal adenocarcinoma (PDAC). Using a functional genome-wide CRISPRi screen in PDAC cells, we identified activators of selective MYC translation through its 5 untranslated region (5UTR) and validated four RNA binding proteins (RBPs), including epitranscriptome modifiers. Among these RBPs, our top hit was RBM42, which is highly expressed in PDAC and predicts poor survival. Combining polysome sequencing and CLIP-seq analyses, we find that RBM42 binds and selectively regulates the translation of MYC and a precise, yet vital suite of pro-oncogenic transcripts, including JUN and EGFR. Mechanistically, employing IP-mass spectrometry analysis, we find that RMB42 is a novel ribosome-associated protein (RAP). Using DMS-Seq and mutagenesis analysis, we show that RBM42 directly binds and remodels the MYC 5UTR RNA structure, facilitating the formation of the translation pre-initiation complex. Importantly, RBM42 is necessary for human PDAC cell growth and fitness and PDAC tumorigenesis in xenograft mouse models in a Myc-dependent manner in vivo. In PDAC patient samples, RBM42 expression is correlated with Myc protein levels and transcriptional activity. This work transforms our understanding of the translational code in cancer and offers a new therapeutic opening to target the expression of oncogenes.

cancer biology↗

Lysosomal retargeting of Myoferlin mitigates membrane stress to enable pancreatic cancer growth

Lysosomes must maintain integrity of their limiting membrane to ensure efficient fusion with incoming organelles and degradation of substrates within their lumen. Pancreatic cancer cells upregulate lysosomal biogenesis to enhance nutrient recycling and stress resistance, but whether dedicated programs for maintaining lysosomal membrane integrity facilitate pancreatic cancer growth is unknown. Using proteomic-based organelle profiling, we identify the Ferlin family plasma membrane repair factor, Myoferlin, as selectively and highly enriched on the membrane of pancreatic cancer lysosomes. Mechanistically, lysosome localization of Myoferlin is necessary and sufficient for maintenance of lysosome health and provides an early-acting protective system against membrane damage that is independent from the endosomal sorting complex required for transport (ESCRT)-mediated repair network. Myoferlin is upregulated in human pancreatic cancer, predicts poor survival, and its ablation severely impairs lysosome function and tumour growth in vivo. Thus, retargeting of plasma membrane repair factors enhances pro-oncogenic activities of the lysosome.

cancer biology↗