Biology subjects

Cross, N. A.

Publications and source records attributed to Cross, N. A..

6 recordsLinked to original sources

bioRxiv2026

Hypoxia-activated prodrug and chemotherapy disrupt resistance-associated metabolism in osteosarcoma

Chemotherapy resistance remains a critical barrier in treating osteosarcoma. Hypoxia-activated prodrugs (HAPs) target oxygen-deprived tumor regions that evade conventional chemotherapy. Here, we applied integrated spatial multimodal mass spectrometry imaging of metabolites (DESI-MSI, MALDI-MSI), targeted proteomics (IMC), and metallomics (LA-ICP-MSI) to naive and newly developed doxorubicin-resistant osteosarcoma spheroids treated with a novel HAP tirapazamine analogue, TPZ-A-X, and doxorubicin. Combination treatment selectively downregulated GLUT1 and suppressed pro-survival pAkt in doxorubicin-resistant spheroids whilst inducing comparable DNA damage ({gamma}H2AX) across both phenotypes. Metabolomics imaging identified ferroptosis pathway suppression in doxorubicin resistance, which combination treatment reversed, whilst simultaneously depleting glycolytic fuels. Integrative protein-metabolite correlation analysis uncovered functional couplings between glucose transport and CoA-dependent metabolism and spatially revealed anabolic signaling at spheroid peripheries. Combination treatment induced endogenous copper, zinc and magnesium depletion, independent of ATP/ADP collapse reflecting an adaptive survival remodeling of the metalloproteome. HAP/chemotherapy combinations exploit metabolic vulnerabilities via coordinated disruption of ferroptosis suppression, glycolytic dependence, and survival pathways underlying apoptotic resistance. These findings demonstrate a framework for informing mechanistic reasoning and combination strategy design in chemotherapy-resistant tumors.

cancer biology↗

bioRxiv2025

Modification of Death receptor-mediated cell death in osteosarcoma cell lines using epigenetic modifiers

Osteosarcoma is a bone malignancy most prevalent in adolescent populations. Despite advances in multi-agent chemotherapies and surgical procedures, the survival rate remains <30% for patients with metastasis. Tumour necrosis factor-related apoptosis inducing ligand (TRAIL) is a promising anti-cancer agent, but when used as a single-agent, TRAIL-resistance occurs. Anti-Death receptor-4 and -5 agonistic mAbs are TRAIL mimetics proven to have higher specificity towards DR4 and DR5 receptor thus avoiding decoy receptors. However, their efficacy is also limited due to rapid development of resistance. In this study, the epigenetic modifiers Trichostatin A, GSK343 and BIX-01294 were explored in combination with an anti-DR5 agonistic mAb (DR5 mAb) to evaluate their anti-cancer efficacy in osteosarcoma cell lines Saos-2 and MG63. These cell lines are known to be insensitive TRAIL-induced apoptosis due to overexpression of membrane-bound and soluble decoy receptors to TRAIL, but are more sensitive to DR5 mAbs. Trichostatin A, a Histone deacetylase inhibitor (HDACi) demonstrated a synergistic effect in sensitising osteosarcoma cells to DR5 mAb. Conversely, inhibitors of the Histone methyltransferase GSK343 (EZH2i) and BIX-01294 (G9ai) in combination with DR5 mAb had an antagonistic effect on apoptosis induction. The drug combinations were also evaluated in 3D alginate tumour spheroids, and both GSK343 and BIX-01294 inhibited DR5 mAb-mediated apoptosis.

cancer biology↗

bioRxiv2023

Assessment of ferroptosis inducers and Nrf2 inhibitors as radiosensitisers in 2D and 3D breast cancer cell cultures

Ferroptosis is a form of programmed cell death that is modulated in some cancer cells as a pro-survival mechanism. Induction of ferroptosis is a potential anti-cancer strategy, and enhancement of ferroptosis has the potential to current anti-tumour mechanisms. In this study, we assessed the effect of the ferroptosis inducers Erastin, RSL-3 and FIN-56 on the radiosensitivity of MCF-7 and MDA-MB-231 breast cancer cell lines in 2D and 3D cell culture. Since some tumours modulate ferroptosis via increased Nrf2 production, and MCF-7 and MDA-MB-231 both produce Nrf2 protein, we also assessed the effects of the Nrf2 inhibitor ML385 on radiosensitivity. MDA-MB-231 was highly sensitive to all ferroptosis inducers, and ferroptosis was reversed by the ferroptosis inhibitors Ferrostatin-1, Liproxstatin-1 and Deferoxamine. MCF-7 was resistant to all ferroptosis inducers. MDA-MB-231 and MCF-7 cells were sensitive to irradiation in 2D cell culture but resistant in 3D alginate spheroids. There was also no robust enhancement to irradiation effects with ferroptosis inducers or ML385 in 2D or 3D cell culture or colony formation assays. Ferroptosis inducers did, however, show heterogeneous responses in 3D cell culture. These studies suggest targeting ferroptosis does not induce enhancement of ferroptotic cell death in breast cancer cells.

cancer biology↗

bioRxiv2022

Programmed death-ligand 1 expression in human cancer three-dimensional cell culture models

Programmed death-ligand 1 (PD-L1) expression is a survival mechanism employed by tumours to mediate immune evasion and tumour progression. PD-1/PD-L1-targeted therapies have revolutionised the cancer therapy landscape due to their ability to promote durable anti-tumour immune responses in select patients with advanced cancers. However, some patients are unresponsive, hyper-progressive or develop resistance. Better characterisation of the 3D architecture of solid tumours by utilising 3D cell culture could provide an environment that more closely recapitulates in vivo human tumours for investigating tumour-intrinsic PD-L1 signalling and immunotherapy responses. Here we investigated whether PD-L1 expression by human breast, prostate and colorectal cancer cell lines altered in 3D cell culture models compared to their 2D monolayer counterparts. We found that PD-L1 expression changed in 3D-cultured cancer cells when compared to 2D-cultured cells. Additionally, the expression of immunological markers, PD-1, PD-L2, CD44, DR4, DR5, Fas, and HLA-ABC were assessed in 3D cell culture and compared to their expression in 2D. These markers were also altered in 3D compared to 2D-cultured cells, highlighting the importance of utilising 3D models which may better able the investigation of tumour-intrinsic PD-L1 signalling, responses to PD-1/PD-L1-targeted therapy, and combination therapies.

cancer biology↗

bioRxiv2022

Dysregulation of stress-induced translational control by Porphyromonas gingivalis in host cells

Periodontitis, a chronic inflammatory gum disease, is caused in part by the periodontopathogen Porphyromonas gingivalis. Infection triggers activation of host inflammatory responses which induce stresses such as oxidative stress. Under such conditions, cells can activate the Integrated Stress Response (ISR), a signalling cascade which functions to determine cellular fate, by either downregulating protein synthesis and initiating a stress-response gene expression program, or if stress cannot be overcome, initiating programmed cell death. Recent studies have implicated the ISR signalling in both host antimicrobial defences and within the pathomechanism of certain microbes. In this study, we investigated how P. gingivalis infection alters translation attenuation during oxidative stress-induced activation of the ISR pathway in oral epithelial cells. P. gingivalis infection alone did not result in ISR activation. In contrast, infection coupled with stress led to differential stress granule formation and composition, along with dysregulation of the microtubule network. Infection also heightened stress-induced translational repression, a response which could not be rescued by ISRIB, a potent ISR inhibitor. Heightened translational repression during stress was observed with both P. gingivalis conditioned media and outer membrane vesicles, implicating the role of a secretory factor, probably proteases known as gingipains, in this exacerbated translational repression. The effects of gingipain inhibitors and gingipains-deficient P. gingivalis mutants further confirmed these pathogen-specific proteases as the effector. Gingipains are known to degrade the mammalian target of rapamycin (mTOR) and these studies implicate the gingipain-mTOR axis as the effector of host translational dysregulation during stress.

microbiology↗

bioRxiv2021

EZH2 inhibition enhances TRAIL responses in multiple myeloma but not in quiescent cells

Multiple Myeloma is a plasma cell malignancy for which there is currently no cure, despite many novel therapies. TRAIL (Tumour necrosis factor-related apoptosis inducing ligand) is a promising anti-tumour agent although TRAIL-insensitive cells readily emerge when used as a single agent and its effects are limited due to many TRAIL-resistant cells which emerge soon after treatment. EZH2 is a H3K27 histone methyltransferase found to be overexpressed in many cancers including Multiple Myeloma. We tested the hypothesis that epigenetic reprogramming using the EZH2 inhibitor GSK343 would enhance TRAIL sensitivity, overcome TRAIL resistance, and target TRAIL-resistant quiescent cell populations. We show that GSK343 is a potent TRAIL sensitiser in TRAIL-sensitive RPMI 8226, NCI-H 929 and U266, and in TRAIL-resistant OPM-2 and JJN3, the latter showing very potent synergistic induction of apoptosis, primarily via caspase-8 activation but also via caspase-9. GSK343-enhancement of TRAIL responses was further enhanced in a 3D cell culture model of Multiple Myeloma in NCI-H 929 and U266. We show that in TRAIL-resistant sub-populations of Multiple Myeloma cells, GSK343 responses were completely attenuated in RPMI 8226 although synergistic enhancement of apoptosis was observed in NCI-H 929. Furthermore, following isolation of PKH26Hi quiescent cell populations, TRAIL responses and enhancement of TRAIL responses by GSK343 were completely attenuated. These studies show that EZH2 inhibition enhances TRAIL responses both in TRAIL-sensitive and TRAIL-resistant MM cell lines suspension culture and also in 3D cell culture to model the semi-solid Multiple Myeloma lesions in bone. Pre-existing TRAIL resistance was also enhanced by EZH2, and although synergistic enhancement of TRAIL responses by GSK343 was seen in NCI-H 929, responses were completely lost in TRAIL-resistant RPMI 8226 and also in quiescent cells. These studies highlight that although EZH2 inhibitors enhance TRAIL responses, acquired TRAIL resistance, and the presence of quiescent cells may mediate TRAIL-insensitivity in response to GSK343.

cancer biology↗