Biology subjects

Anand, J.

Publications and source records attributed to Anand, J..

5 recordsLinked to original sources

bioRxiv2025

DIFFERENTIAL ROLES OF RAD18 IN REPRESSING CARCINOGEN- AND ONCOGENE-DRIVEN MUTAGENESIS IN VIVO

The DNA repair protein RAD18 activates Y-family Trans-Lesion Synthesis (TLS) DNA polymerases that are DNA damage-tolerant and potentially error-prone. RAD18 is also frequently overexpressed and pathologically activated in cancer cells. However, the extent to which RAD18 shapes cancer genomes and impacts tumorigenesis is unclear. Therefore, we tested the effect of Rad18 status on chemically-induced and oncogene-driven tumorigenesis. In a chemically-induced oral carcinogenesis model, acute (2-16 days) 4NQO-treatment induces expression of Rad18 and TLS polymerase mRNAs in mouse oral epithelial cells prior to emergence of oral squamous cell carcinomas (OSCCs). Chronic (8 week) 4NQO-treatment leads to onset of oral tumors that is accelerated in Rad18-/- mice when compared with Rad18+/+ animals. Analysis of OSCC exomes reveals increased levels of G(C)>T(A) transversions in Rad18-/- tumors when compared with Rad18+/+. Therefore, Rad18 promotes error-free bypass of 4NQO-induced DNA lesions and suppresses 4NQO-induced oral carcinogenesis. In a KrasG12D-induced lung carcinogenesis model, Rad18-deficiency did not affect rates or incidence of oncogene-induced lung tumors or mutations. Taken together, we demonstrate that Rad18 has context-specific tumor-suppressive activity. Given the prevalence of 4NQO-like environmental exposures, RAD18 is highly likely to shape human cancer genomes and perhaps influence other aspects of the tumorigenic process.

cancer biology↗

bioRxiv2023

Paracrine secretion of MUFAs prevents ferroptosis in triple-negative breast cancer and reveals selenocysteine synthesis dependency for lung metastasis

The limited availability of therapeutic options for patients with triple-negative breast cancer (TNBC) contributes to the high rate of metastatic recurrence and poor prognosis. Ferroptosis is a type of cell death caused by iron-dependent lipid peroxidation and counteracted by the antioxidant activity of the selenoprotein GPX4. Here, we show that TNBC cells secrete an anti-ferroptotic factor in the extracellular environment when cultured at high cell densities but are primed to ferroptosis when forming colonies at low density. We found that secretion of the anti-ferroptotic factors, identified as monounsaturated fatty acid (MUFA) containing lipids, and the vulnerability to ferroptosis of single cells depends on the low expression of stearyl-CoA desaturase (SCD) that is proportional to cell density. Finally, we show that the inhibition of Sec-tRNAsec biosynthesis, an essential step for selenoprotein production, causes ferroptosis and impairs the lung seeding of circulating TNBC cells that are no longer protected by the MUFA-rich environment of the primary tumour.

cancer biology↗

bioRxiv2022

Spatial regulation of the glycocalyx component Podocalyxin is a switch for pro-metastatic function

The glycocalyx component and sialomucin Podocalyxin (PODXL) is required for normal tissue development by promoting apical membranes to form between cells, triggering lumen formation. Elevated PODXL expression is also associated with metastasis and poor clinical outcome in multiple tumour types. How PODXL presents this duality in effect remains unknown. We identify an unexpected function of PODXL as a decoy receptor for Galectin-3 (GAL3), whereby the PODXL-GAL3 interaction releases GAL3 repression of integrin-based invasion. Differential cortical targeting of PODXL, regulated by ubiquitination, is the molecular mechanism controlling alternate fates. Both PODXL high versus low surface levels occur in parallel subpopulations within cancer cells. Orthotopic intraprostatic xenograft of PODXL-manipulated cells or those with different surface levels of PODXL define that this axis controls metastasis in vivo. Clinically, interplay between PODXL-GAL3 stratifies prostate cancer patients with poor outcome. Our studies define the molecular mechanisms and context in which PODXL promotes invasion and metastasis.

cell biology↗

bioRxiv2022

The small GTPase ARF3 controls metastasis and invasion modality by regulating N-cadherin levels.

ARF GTPases are central regulators of membrane trafficking that act by controlling local membrane identity and remodelling to facilitate vesicle formation. Unravelling ARF GTPase function is complicated by the overlapping association of ARFs with guanine nucleotide exchange factors (GEFs), GTPase-activating proteins (GAPs), and numerous interactors. The extent to which redundancy is a major factor in ARF function or whether individual ARF GTPases make unique contributions to cellular behaviour remains unclear. Through a functional genomic screen of 3-Dimensional (3D) prostate cancer cell behaviour we explore the contribution of all known ARF GTPases, GEFs, GAPs, and a large selection of interactors to collective morphogenesis. This revealed that the ARF3 GTPase regulates the modality of invasion, acting as a switch between leader cell-led chains of invasion or collective sheet movement. Functionally, the ability of ARF3 to control invasion modality is dependent on association and subsequent control of the junctional adhesion molecule N-cadherin. In vivo, ARF3 levels acted as a rheostat for metastasis from intraprostatic tumour transplants and ARF3:N-cadherin expression can be used to identify prostate cancer patients with metastatic, poor-outcome disease. Our analysis defines a unique function for the ARF3 GTPase in controlling how cells collectively organise during invasion and metastasis.

cell biology↗

bioRxiv2020

Systematic functional analysis of Leishmania protein kinases identifies regulators of differentiation and survival

Differentiation between distinct stages is fundamental for the life cycle of intracellular protozoan parasites and for transmission between hosts, requiring stringent spatial and temporal regulation. Here we applied kinome-wide gene deletion and gene tagging in Leishmania mexicana promastigotes to define protein kinases with life cycle transition roles. Whilst 162 were dispensable, 44 protein kinase genes were refractory to deletion in promastigotes and are likely core genes required for parasite replication. Phenotyping of pooled gene deletion mutants using bar-seq and projection pursuit clustering revealed functional phenotypic groups of protein kinases involved in differentiation from metacyclic promastigote to amastigote, growth and survival in macrophages and mice, colonisation of the sand fly and motility. This unbiased interrogation of protein kinase function in Leishmania allows targeted investigation of organelle-associated signalling pathways required for successful intracellular parasitism.

microbiology↗