Biology subjects

Kumar, R. V.

Publications and source records attributed to Kumar, R. V..

4 recordsLinked to original sources

bioRxiv2026

Paternal folate deficiency reveals meiosis as a metabolic sensing window in the male germline

Folate-dependent one-carbon metabolism supplies methyl donors required for chromatin modification, yet how metabolic conditions shape epigenome establishment in the male germline remains poorly understood. Here, using a folate-deficient mouse model, we identify meiotic prophase I as a metabolically sensitive window in the male germline. By integrating in vivo germline analysis with bulk and single-cell transcriptomic and epigenomic profiling, we show that folate deficiency disturbs transcriptional programs in pachytene spermatocytes and preferentially perturbs CpG island (CGI)-associated promoters, which are characterized by bivalent H3K4me3 and H3K27me3 during meiosis. Consistent with this selective vulnerability, active chromatin marks, including H3K4me3 and H3K27ac, are markedly reduced at CGI-associated promoters under folate-deficient conditions. Notably, loci that later exhibit altered H3K4me3 enrichment in mature sperm show earlier chromatin perturbations during meiosis, suggesting that these sperm epigenomic alterations may originate during meiotic development. Together, these findings establish a mechanistic link between paternal folate deficiency and dynamic epigenomic remodeling of CGI-associated chromatin in the male germline.

developmental biology↗

bioRxiv2025

Stromal LOX/FAK/beta catenin pathway locks mammary fibroblasts into a tumor-promoting myCAF state

BackgroundCancer-associated fibroblasts (CAFs) sustain tumor progression, yet the soluble cues that maintain their myofibroblast (myCAF) state are poorly defined. Transforming growth factor beta (TGF-{beta}) is a canonical CAF activator. This study aims to identify TGF-{beta}-induced secreted mediators that reinforce the myCAF phenotype in breast cancer and map the downstream signaling cascade. Methods and ResultsSecretome profiling of primary patient-derived myCAFs and human mammary fibroblasts (HMF3s) engineered to over-express TGF-{beta}1 revealed 20 extracellular-matrix remodelers shared exclusively by both activated states; lysyl oxidase (LOX) was the top-ranked hit. LOX knockdown abrogated TGF-{beta}-driven -smooth-muscle actin (-SMA) induction, collagen-gel contraction and migration in HMF3s, and reduced constitutive -SMA and {beta}-catenin in myCAFs. Mechanistically, TGF-{beta} upregulated LOX, which activated focal-adhesion kinase (FAK), leading to p38 MAPK- and Akt-mediated Ser9 phosphorylation (inactivation) of GSK3{beta} and consequent {beta}-catenin stabilization. In HCC1806-luciferase orthotopic xenografts, CAFs accelerated tumor growth, whereas LOX-deficient CAFs lost this pro-tumoral effect. ConclusionLOX is a pivotal autocrine effector of TGF-{beta} that locks breast CAFs into a pro-tumoral myCAF state through a LOX/FAK/GSK3{beta}/{beta}-catenin axis. Targeting stromal LOX may disrupt CAF activation and curb breast cancer progression.

cancer biology↗

bioRxiv2021

Galectin-9 signaling drives breast cancer invasion through matrix

Aberration in expression and function of glycans and their binding proteins (lectins) in transformed cells constitutes one of the earliest discovered hallmarks of cancer. Galectins are a conserved family of lectins that can bind to {beta}-galactosides. Among them, the role of Galectin-9, a galectin with two carbohydrate binding domains in immune-tumor cell interactions has been well-established, although its effect on cancer cell behavior remains as yet unclear. In this study, we used a spectrum of cell lines from homeostatic breast cells to transformed non-invasive and invasive cell lines cultured in microenvironment-diverse conditions to show that Galectin-9 expression shows an elevation in association with invasiveness of breast cancer epithelia. Our observations were supported by immunohistochemical studies of breast tumors and adjacent normal-tissues from patients. Genetic perturbation of Galectin-9 as well as the pharmacological inhibition of activity using cognate inhibitors confirmed a positive correlation between Galectin-9 levels and the adhesion of the aggressive triple negative breast cancer cells MDA-MB-231 to- and their invasion through-extracellular matrices (ECM). Within a constituted organomimetic multiECM microenvironment, Galectin-9 enhanced both the solitary and the collective invasion of cancer cells. Quantitative proteomics led us to uncover the inductive role of Galectin-9 in the expression of the proinvasive protein S100A4. In addition, Galectin-9 expression correlated with FAK signaling, the inhibition of which decreased S100A4 mRNA levels. Our results provide crucial signaling insights into how the elevation in Galectin-9 expression in breast cancer cells potentiates their invasiveness through ECM during early steps of metastasis.

cancer biology↗

bioRxiv2020

ST6GAL1-mediated heterogeneity in sialic acid levels potentiates invasion of breast cancer epithelia

Heterogeneity in phenotypes of malignantly transformed cells and aberrant glycan expression on their surface are two prominent hallmarks of cancers that have hitherto not been linked to each other. In this paper, we identify heterogeneity in a specific glycan linkage: 2,6-linked sialic acids within breast cancer cells in vivo and in culture. Upon sorting out two populations with moderate and relatively higher cell surface 2,6-linked sialic acid levels from the triple negative breast cancer cell line MDA-MB-231, both populations (denoted as medium and high-2,6-Sial cells respectively) stably retained their levels in early passages. Upon continuous culturing, medium 2,6-Sial cells recapitulated the heterogeneity of the unsorted line whereas high 2,6-Sial cells showed no such tendency. Compared with the high 2,6-Sial, the medium 2,6-Sial cells showed greater adhesion to reconstituted extracellular matrices (ECM) as well as invaded faster as single cells. The level of 2,6-linked sialic acids in the two sublines was found to be consistent with the expression of a specific glycosyl transferase, ST6GAL1. Stably knocking down ST6GAL1 in the high 2,6-Sial cells, enhanced their invasiveness. When cultured together, medium 2,6-Sial cells differentially migrated to the edge of growing tumoroid-like cultures, whereas high 2,6-Sial cells formed the central bulk. Simulations in a Cellular Potts model-based computational environment that is calibrated to our experimental findings suggest that the heterogeneity of cell-ECM adhesion, likely regulated by 2,6-linked sialic acids facilitates niches of highly invasive cells to efficiently migrate centrifugally as the invasive front of a malignant tumor. Significance StatementCell-surface sugars are aberrantly expressed in cancer but their contributions to tumor heterogeneity are not known. In this study, we uncover and separate breast cancer populations with distinct 2,6-linked sialic acid levels. The moderately expressing population shows stronger adhesion to extracellular matrix than the high expressing population. It also invades faster through the matrix as single cells. Combining experiments with computational modelling, we show that the heterogeneity in matrix adhesion is vital to accentuating cell invasion. In some conditions, invasion of heterogeneous populations may compare with, or exceed that of, homogeneous moderately expressing populations. Our findings are vital to furthering our understanding of how cancers spread and potentially qualify efforts to manage the disease through glycan-editing or immunotherapeutic approaches.

cancer biology↗