Rakshe, S. | Search bioRxiv

bioRxiv2025

Long Noncoding RNAs Enforce Pancreatic Cancer Identity and Block Reprogramming

The Yamanaka factors (OCT4, SOX2, KLF4, and MYC; OSKM) can rejuvenate aging phenotypes in somatic cell types by resetting the epigenetic landscape. Curiously, most solid tumor cells remain largely resistant to reprogramming despite their well-documented plasticity, and the underlying mechanisms are unclear. Here, we combined genomic profiling and in vivo assays to investigate OSKM-mediated reprogramming of pancreatic ductal adenocarcinoma (PDAC). In the initial stages, we found that cancer-specific genes were refractory while mesodermal/ECM programs, normally silenced by PRC2, were aberrantly upregulated. A CRISPR interference screen for OSKM reprogramming coupled with functional analyses revealed that suppression of cancer-associated long noncoding RNAs (lncRNAs) erased malignant epithelial programs, restored tumor suppressor activity, and impaired tumorigenicity in vivo. We further identified that ATXN7L3-AS1 lncRNA sustains the PDAC malignant identity through its association with active epithelial oncogenic programs and poised PRC2-targeted developmental genes, thereby supporting both plasticity and memory. Thus, by exploring why cancer cells are resistant to reprogramming, we identify lncRNAs as gatekeepers of malignant identity, suggesting that targeting lncRNAs could be a generalizable therapeutic strategy in treating solid tumors.

cancer biology↗

bioRxiv2024

Metabolomic and transcriptomic remodeling of bone marrow myeloid cells in response to maternal obesity

Maternal obesity puts the offspring at high risk of developing obesity and cardio-metabolic diseases in adulthood. Here, using a mouse model of maternal high-fat diet (HFD)-induced obesity, we show that whole body fat content of the offspring of HFD-fed mothers (Off-HFD) increases significantly from very early age when compared to the offspring regular diet-fed mothers (Off-RD). We have previously shown significant metabolic and immune perturbations in the bone marrow of newly-weaned offspring of obese mothers. Therefore, we hypothesized that lipid metabolism is altered in the bone marrow Off-HFD in newly-weaned offspring of obese mothers when compared to the Off-RD. To test this hypothesis, we investigated the lipidomic profile of bone marrow cells collected from three-week-old offspring of regular and high fat diet-fed mothers. Diacylgycerols (DAGs), triacylglycerols (TAGs), sphingolipids and phospholipids, including plasmalogen, and lysophospholipids were remarkably different between the groups, independent of fetal sex. Levels of cholesteryl esters were significantly decreased in offspring of obese mothers, suggesting reduced delivery of cholesterol to bone marrow cells. This was accompanied by age-dependent progression of mitochondrial dysfunction in bone marrow cells. We subsequently isolated CD11b+ myeloid cells from three-week-old mice and conducted metabolomics, lipidomics, and transcriptomics analyses. The lipidomic profiles of these bone marrow myeloid cells were largely similar to that seen in bone marrow cells and included increases in DAGs and phospholipids alongside decreased TAGs, except for long-chain TAGs, which were significantly increased. Our data also revealed significant sex-dependent changes in amino acids and metabolites related to energy metabolism. Transcriptomic analysis revealed altered expression of genes related to major immune pathways including macrophage alternative activation, B-cell receptor signaling, TGF{beta} signaling, and communication between the innate and adaptive immune systems. All told, this study revealed lipidomic, metabolomic, and gene expression abnormalities in bone marrow cells broadly, and in bone marrow myeloid cells particularly, in the newly-weaned offspring of obese mothers, which might at least partially explain the progression of metabolic and cardiovascular diseases in their adulthood.

molecular biology↗