Biology subjects

Collard, T. J.

Publications and source records attributed to Collard, T. J..

4 recordsLinked to original sources

bioRxiv2022

Aspirin reprogrammes colorectal cancer cell metabolism and sensitises to glutaminase inhibition

To support proliferation and survival within a challenging microenvironment, cancer cells must reprogramme their metabolism. As such, targeting cancer cell metabolism is a promising therapeutic avenue. However, identifying tractable nodes of metabolic vulnerability in cancer cells is challenging due to their metabolic plasticity. Identification of effective treatment combinations to counter this is an active area of research. Aspirin has a well-established role in cancer prevention, particularly in colorectal cancer (CRC), although the mechanisms are not fully understood. Here, we comprehensively characterise the metabolic impact of long-term aspirin exposure (2-4mM for 52 weeks) on CRC cells. We show that aspirin regulates several enzymes and transporters of central carbon metabolism and results in a reduction in glutaminolysis and a concomitant increase in glucose metabolism, demonstrating reprogramming of nutrient utilisation. We show that aspirin causes likely compensatory changes that renders the cells sensitive to the glutaminase 1 (GLS1) inhibitor - CB-839. Of note given the clinical interest, treatment with CB-839 alone had little effect on CRC cell growth or survival. However, in combination with aspirin, CB-839 inhibited CRC cell proliferation and induced apoptosis in vitro, and importantly, reduced crypt proliferation in Apcfl/fl mice in vivo. Together, these results show that aspirin leads to significant metabolic reprogramming in colorectal cancer cells and raises the possibility that aspirin could significantly increase the efficacy of metabolic cancer therapies in CRC.

cancer biology↗

bioRxiv2022

Identifying targetable metabolic dependencies across colorectal cancer progression

Colorectal cancer (CRC) is a multi-stage process initiated through the formation of a benign adenoma, progressing to an invasive carcinoma and finally metastatic spread. Tumour cells must adapt their metabolism to support the energetic and biosynthetic demands associated with disease progression. As such, targeting cancer cell metabolism is a promising therapeutic avenue in CRC. However, to identify tractable nodes of metabolic vulnerability specific to CRC stage, we must understand how metabolism changes during CRC development. Here, we use a unique model system - comprising human early adenoma to late adenocarcinoma. We show that adenoma cells transition to elevated glycolysis at the early stages of tumour progression but maintain oxidative metabolism. Progressed adenocarcinoma cells rely more on glutamine-derived carbon to fuel the TCA cycle, whereas glycolysis and TCA cycle activity remain tightly coupled in early adenoma cells. Adenocarcinoma cells are more flexible with respect to fuel source, enabling them to proliferate in nutrient-poor environments. Despite this plasticity, we identify asparagine (ASN) synthesis as a node of metabolic vulnerability in late-stage adenocarcinoma cells. We show that loss of asparagine synthetase (ASNS) blocks their proliferation, whereas early adenoma cells are largely resistant to ASN deprivation. Mechanistically, we show that late-stage adenocarcinoma cells are dependent on ASNS to support mTORC1 signalling and maximal glycolytic and oxidative capacity. Resistance to ASNS loss in early adenoma cells is likely due to a feedback loop, absent in late-stage cells, allowing them to sense and regulate ASN levels and supplement ASN by autophagy. Together, our study defines metabolic changes during CRC development and highlights ASN synthesis as a targetable metabolic vulnerability in later stage disease.

cancer biology↗

bioRxiv2021

Loss of BCL-3 sensitises colorectal cancer cells to DNA damage, revealing a role for BCL-3 in double strand break repair by homologous recombination

ObjectiveThe proto-oncogene BCL-3 is upregulated in a subset of colorectal cancers (CRC) and increased expression of the gene correlates with poor patient prognosis. The aim is to investigate whether inhibiting BCL-3 can increase the response to DNA damage in CRC. DesignThe function of BCL-3 in DNA damage response was studied in vitro using siRNA and CRISPR-Cas9 genome editing and in vivo using Bcl3-/- mice. DNA damage induced by {gamma}-irradiation and/or cisplatin was quantified using H2AX and RAD51 foci, repair pathways investigated using HR/NHEJ assays and treatment with the PARP inhibitor olaparib. ResultSuppression of BCL-3 increases double strand break number and decreases homologous recombination in CRC cells, supported by reduced RAD51 foci number and increased sensitivity to PARP inhibition. Importantly, a similar phenotype is seen in Bcl3-/- mice, where the intestinal crypts of these mice exhibit sensitivity to DNA damage and a greater number of double strand breaks compared to wild type mice. Furthermore Apc.Krasmutant x Bcl3-/- mice exhibit increased DNA damage and reduced RAD51+ cells compared to their wild type counterparts when treated with cisplatin. ConclusionThis work identifies BCL-3 as a regulator of the cellular response to DNA damage and suggests that elevated BCL-3 expression could increase resistance of tumour cells to DNA damaging agents including radiotherapy. These findings offer a rationale for targeting BCL-3 in CRC as an adjuvant to conventional therapies and suggest that BCL-3 expression in tumours could be a useful biomarker in stratification of rectal cancer patients for neo-adjuvant chemoradiotherapy.

cancer biology↗

bioRxiv2017

BCL-3 enhances β-catenin signalling in colorectal tumour cells promoting a cancer stem cell phenotype

Increased nuclear BCL-3 (a key regulator of inflammation and NF-{kappa}B signalling when associated with p50 or p52 homodimers) has been reported in a subset of colorectal cancers, but its role in colorectal tumorigenesis remains poorly understood. Interestingly, recent studies have highlighted the importance of the interplay between NF-{kappa}B signalling and the Wnt/{beta}-catenin pathway in colorectal epithelial cells, reporting that non-stem cells engineered to undergo high levels of Wnt and NF-{kappa}B signalling can de-differentiate, initiating tumours in mice. Here we show that BCL-3 is an important co-activator of {beta}-catenin/TCF-mediated transcriptional activity in colorectal cancer cells, increasing expression of Wnt-regulated intestinal stem cell genes. We demonstrate RNAi-mediated BCL-3 suppression reduced {beta}-catenin/TCF-dependent transcription and the expression of intestinal stem cell genes and Wnt targets LGR5 and ASCL2. Further we show that BCL-3 promotes the stem cell phenotype in colorectal cancer cells by increasing colorectal spheroid and tumoursphere formation in 3D culture conditions. Our data suggest that targeting BCL-3 may represent an exciting new approach for CRC treatment, particularly as it acts downstream of frequently mutated APC and {beta}-catenin.

cancer biology↗