Biology subjects

Kovacevic, Z.

Publications and source records attributed to Kovacevic, Z..

3 recordsLinked to original sources

bioRxiv2025

Silencing the signal: The metastasis suppressor NDRG1 disrupts exosome-mediated crosstalk in pancreatic cancer

Pancreatic cancer (PaC) remains one of the deadliest cancers, with 5-year survival rates of 13%. A major driver of its aggressiveness is the tumour microenvironment (TME), which fuels tumour growth, metastasis, and therapeutic resistance through dynamic, bi-directional communication between cancer cells, fibroblasts, and immune cells. Emerging evidence highlights extracellular vesicles (EVs) as key mediators of oncogenic cross-talk within the PaC TME. This study demonstrates for the first time that the metastasis suppressor NDRG1 significantly influences the biogenesis, cargo packaging and release of EVs by cancer cells. This was mediated by a direct interaction between NDRG1 and ALIX, a key protein involved in EV biogenesis and packaging, with NDRG1 facilitating ALIX proteasomal degradation. Further, EVs released from NDRG1-overexpressing cells had significantly fewer CAF-activation proteins (i.e. TGF-B), leading to attenuated ERKl/2 and p38 activation in pancreatic stellate cells (PSCs), and reduced expression of key fibrotic markers (a-SMA, FAP, and collagen 1A). NDRG1 also reduced EV uptake by PaC cells and diverted these to the lysosome for degradation. These findings uncover a previously unrecognized mechanism by which NDRG1 disrupts the oncogenic two-way communication between PaC cells and the TME, positioning NDRG1 as a compelling therapeutic target against this formidable malignancy. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=123 SRC="FIGDIR/small/682724v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@154b908org.highwire.dtl.DTLVardef@13fe6f5org.highwire.dtl.DTLVardef@540fadorg.highwire.dtl.DTLVardef@d15636_HPS_FORMAT_FIGEXP M_FIG C_FIG

cancer biology↗

bioRxiv2023

Melanotransferrin Functions as a Pro-Oncogenic WNT Agonist: A Yin-Yang Relationship in Melanoma with the WNT Antagonist and Metastasis Suppressor, NDRG1

A persistent mystery in the melanoma field has been the function of one of the first melanoma tumor antigens characterized, namely p97 (melanotransferrin; MTf). While MTf expression increases melanoma cell proliferation, migration, and tumorigenesis, the molecular mechanism responsible is unknown. On the other hand, N-myc down-stream regulated gene 1 (NDRG1) is a potent metastasis suppressor and WNT antagonist. Expression of NDRG1 in melanoma cells suggests a role in inhibiting metastasis, with this study investigating MTfs role in oncogenic signaling. We demonstrate MTf acts as a pro-oncogenic WNT agonist, which down-regulates NDRG1, while silencing MTf increases NDRG1 expression. In contrast, silencing NDRG1 increases MTf expression. These observations demonstrate a bidirectional negative feedback loop and "Yin-Yang" relationship between MTf and NDRG1. Mechanistically, MTf was directly associated with the WNT co-receptor, lipoprotein-receptor 6 (LRP6), and increased total LRP6 expression, activated p-LRP6 (Ser1490), {beta}-catenin, and activated {beta}-catenin (Ser552) levels, with MTf expression inducing their nuclear accumulation. Additionally, MTf expression increased downstream WNT targets, namely cyclin D1 and c-Myc, with c-Myc down-regulating NDRG1 expression. Silencing c-Myc prevented the Yin-Yang relationship between NDRG1 and MTf, indicating c-Myc played a key role in their inverse regulation. Melanoma patient specimens demonstrated that a low NDRG1/MTf ratio was significantly (p = 0.008) associated with lower survival and metastasis. Chemotherapeutic agents that up-regulated NDRG1 depressed MTf and nuclear LRP6 and potently inhibited melanoma xenograft growth in vivo. This study demonstrates MTf acts as a WNT agonist, with a Yin-Yang relationship being observed with the WNT antagonist, NDRG1.

cancer biology↗

bioRxiv2023

An Innovative Non-Hormonal Strategy Targeting Redox Active Metals to Down-Regulate Estrogen-, Progesterone-, Androgen- and Prolactin-Receptors in Breast Cancer

Estrogen receptor- (ER-) is a key driver of breast cancer (BC) targeted by tamoxifen. However, tamoxifen resistance is a major problem. An important mechanism of resistance is the activation of EGFR/HER2/HER3 signaling and other hormone receptors (androgen receptor (AR), progesterone receptor (PR), prolactin receptor (PRL-R)) that intrinsically activate ER-. Hence, therapeutics targeting multiple receptors, rather than ER- alone, would be extremely useful and may overcome tamoxifen resistance. This study examined the activity of redox-active di-2-pyridylketone-4,4-dimethyl-3-thiosemicarbazone (Dp44mT) and di-2-pyridylketone-4-cyclohexyl-4-methyl-3-thiosemicarbazone (DpC), on the expression and activation of crucial hormone receptors, their co-factors, and key resistance pathways in ER--positive BC. Strikingly, DpC differentially regulated 106 estrogen-response genes with Sankey diagram analysis demonstrating this was linked to decreased mRNA levels of 4 central hormone receptors involved in BC pathogenesis, namely ER, PR, AR, and PRL-R. Mechanistic dissection demonstrated that due to DpC and Dp44mT binding metal ions, these agents caused a pronounced decrease in ER-, AR, PR, and PRL-R protein expression. Ablation of the metal-binding site in the thiosemicarbazone totally prevented its suppressive activity, demonstrating a unique non-hormonal mechanism. DpC and Dp44mT also inhibited EGFR, HER2, and HER3 activation, their downstream signaling, and the expression of co-factors that promote ER- transcriptional activity, including SRC3, NF-{kappa}B p65, and SP1. In vivo, DpC was highly tolerable and effectively inhibited ER--positive BC growth. In conclusion, through a bespoke non-hormonal mechanism targeting redox active metals, Dp44mT and DpC disrupt multiple key inter-receptor interactions between PR, AR, PRL-R, and tyrosine kinases that act with ER- to promote BC, constituting an innovative therapeutic approach.

cancer biology↗