Biology subjects

Howell, S. J.

Publications and source records attributed to Howell, S. J..

6 recordsLinked to original sources

bioRxiv2025

Progesterone Receptor Expressing Basal Cells and Progesterone Receptor-Primed Progenitors Redefine the Mammary Epithelial Hierarchy

The central role of progesterone in breast biology and cancer is undeniable. Progesterone is a potent mitogen for mammary stem cell expansion and essential for mammopoiesis, yet only a fraction of the luminal epithelium is described to express the progesterone receptor (PR). Progestins in contraceptives and HRT regimens increases breast cancer risk, whilst progesterone inhibition reduces mammary tumorigenesis. Understanding PR within mammary epithelial dynamics is imperative, especially given mammary stem/progenitors cells are the cells-of-origin in breast cancer. Here, we show PR-primed progenitors contribute to both mammary lineages and expose a novel PR+ basal population, challenging current dogma in the field. PR lineage-tracing yields an unprecedented contribution to the luminal and basal compartments. We uncover an asymmetrically dividing PR-primed subpopulation, which has unique bipotent clonogenic capacity and forms TEB-like outgrowths upon transplantation. We enumerate PR+ basal cells and dissect their proteomic landscape, establishing PR+ basal cells as a discrete basal subset, disparate from luminal PR+ cells. Finally, we identify PR+ basal cells in multiple proteomes, scRNAseq datasets and localize PR in clinical breast specimens. This forms a new foundation for comprehending hormone receptor patterning in the breast, not only based on lineage-identity but also the progenitor-progeny hierarchy. Our study shifts the current paradigm of breast biology with implications for breast cancer treatment given the growing interest in anti-progestin based primary prevention strategies.

cell biology↗

bioRxiv2023

Subtype-specific circadian clock dysregulation modulates breast cancer biology, invasiveness, and prognosis.

Studies in shift workers and model organisms link circadian disruption to breast cancer. However, molecular rhythms in non-cancerous and cancerous human breast tissues are largely unknown. We reconstructed rhythms informatically, integrating locally collected, time-stamped biopsies with public datasets. For non-cancerous tissue, the inferred order of core-circadian genes matches established physiology. Inflammatory, epithelial-mesenchymal transition (EMT), and estrogen responsiveness pathways show circadian modulation. Among tumors, clock correlation analysis demonstrates subtype-specific changes in circadian organization. Luminal A organoids and informatic ordering of Luminal A samples exhibit continued, albeit disrupted rhythms. However, CYCLOPS magnitude, a measure of global rhythm strength, varied widely among Luminal A samples. Cycling of EMT pathway genes was markedly increased in high-magnitude Luminal A tumors. Patients with high-magnitude tumors had reduced 5-year survival. Correspondingly, 3D Luminal A cultures show reduced invasion following molecular clock disruption. This study links subtype-specific circadian disruption in breast cancer to EMT, metastatic potential, and prognosis.

cancer biology↗

bioRxiv2020

Targeting STAT3 signalling using stabilised sulforaphane (SFX-01) inhibits endocrine resistant stem-like cells in ER-positive breast cancer

PURPOSEEstrogen receptor (ER) positive breast cancer is frequently sensitive to endocrine therapy. Multiple mechanisms of endocrine therapy resistance have been identified, including cancer stem-like cell (CSC) activity. Sulforaphane (SFN) has previously been shown to target CSCs but its mechanism of action is unclear. Here we investigate SFX-01, a stabilised formulation of SFN, for its effects on breast CSC activity in ER+ preclinical models and to study its mechanism. EXPERIMENTAL DESIGNCSC activity was measured by mammosphere formation efficiency (MFE), aldehyde dehydrogenase (ALDH) activity, and tumor formation using patient samples and patient-derived xenograft (PDX) tumors treated with SFX-01 alone or in combination with tamoxifen or fulvestrant. Gene expression and SFN target proteins in treated samples were assessed. RESULTSSFX-01 reduced MFE of both ER+ primary and metastatic patient samples. Both tamoxifen and fulvestrant increased MFE and ALDH activity of PDX tumors, which was reversed by combination with SFX-01. SFX-01 significantly reduced tumor initiating cell frequency in secondary transplants at limiting dilution and reduced the formation of spontaneous lung micrometastases by PDX tumors in mice. Mechanistically, we establish that both tamoxifen and fulvestrant induce STAT3 phosphorylation. SFX-01 suppressed phospho-STAT3 and SFN directly bound STAT3 in patient and PDX samples. Analysis of ALDH+ cells from endocrine-resistant patient samples revealed activation of STAT3 target genes MUC1 and OSMR, which were inhibited by SFX-01 in patient samples. Increased expression of these genes after 3 months endocrine treatment of ER+ patients (n=68) predicted poor prognosis. CONCLUSIONSOur data establish the importance of STAT3 signaling in CSC-mediated resistance to endocrine therapy and the potential of SFX-01 for improving clinical outcomes in ER+ breast cancer.

cancer biology↗

bioRxiv2019

A dormant sub-population expressing interleukin-1 receptor characterises anti-estrogen resistant ALDH+ breast cancer stem cells

Estrogen receptor-positive (ER+) breast tumours are often treated with anti-estrogen (AE) therapies but frequently develop resistance. Cancer Stem Cells (CSCs) with high aldehyde dehydrogenase (ALDH) activity (ALDH+ cells) are reported to be enriched following AE treatment. Here we perform in vitro and in vivo functional CSC assays and gene expression analysis to characterise the ALDH+ population in AE resistant metastatic patient samples and an ER+ cell line. We show that the IL1{beta} signalling pathway is activated in ALDH+ cells and data from single cells reveals that AE treatment selects for IL1R1-expressing ALDH+ cells. Importantly, we demonstrate that increased expression of IL1R1 is observed in the tumours of patients treated with AE therapy and predicts for treatment failure. Single-cell gene expression analysis revealed that at least 2 sub-populations exist within the ALDH+ population, one proliferative and one quiescent. Following AE therapy, the quiescent ALDH+IL1R1+ population is expanded, which suggests CSC dormancy as an adaptive strategy that facilitates treatment resistance. Supporting this, analysis of AE resistant dormant tumours reveals significantly increased expression of ALDH1A1, ALDH1A3 and IL1R1 genes. Thus, we propose that targeting of ALDH+IL1R1+ cells will reverse AE resistance, including in patients with minimal residual disease.

cancer biology↗

bioRxiv2019

The Dialysis Procedure Triggers Autonomic Imbalance and Cardiac Arrhythmias: Insights from Continuous 14-day ECG Monitoring

BackgroundIn end-stage kidney disease the dialytic cycle relates to the rate of sudden cardiac death. We hypothesized that circadian, dialytic cycles, paroxysmal arrhythmias, and cardiovascular risk factors are associated with periodic changes in heart rate and heart rate variability (HRV) in incident dialysis patients.\n\nMethodsWe conducted a prospective ancillary study of the Predictors of Arrhythmic and Cardiovascular Risk in End Stage Renal Disease cohort (n=28; age 54{+/-}13 y; 57% men; 96% black; 33% with a history of structural heart disease; left ventricular ejection fraction 70{+/-}9%). Continuous ECG monitoring was performed using an ECG patch (Zio Patch, iRhythm) and short-term HRV was measured for three minutes every hour. HRV was measured by root mean square of the successive normal-to-normal intervals (rMSSD), high and low frequency power, Poincare plot, and sample and Renyi entropy.\n\nResultsArrhythmias were detected in 46% (n=13). Non-sustained ventricular tachycardia (VT) was more frequent during dialysis or within 6 hours post-dialysis, as compared to pre-or between-dialysis (63% vs. 37%, P=0.015), whereas supraventricular tachycardia was more frequent pre-/ between-dialysis, as compared to during-/ post-dialysis (84% vs. 16%, P=0.015). In adjusted for cardiovascular disease and its risk factors autoregressive conditional heteroscedasticity panel (ARCH) model, VT events were associated with increased heart rate by 11.2 (95%CI 10.1-12.3) bpm (P<0.0001). During regular dialytic cycle, rMSSD demonstrated significant circadian pattern (Mesor 10.6(0.9-11.2) ms; Amplitude 1.5(1.0-3.1) ms; Peak at 02:01(20:22-03:16) am; P<0.0001), which was abolished on a second day interdialytic extension (adjusted ARCH trend for rMSSD -1.41(-1.67 to -1.15) ms per 24h; P<0.0001).\n\nConclusionCardiac arrhythmias associate with dialytic phase. Regular dialytic schedule preserves physiological circadian rhythm, but the second day without dialysis is characterized by parasympathetic withdrawal and a steady increase in sympathetic predominance.\n\nSubject TermsArrhythmias, Autonomic Nervous System, Electrocardiology (ECG), Treatment.

epidemiology↗

bioRxiv2019

PAK4 regulates stemness and progression in endocrine resistant ER-positive metastatic breast cancer

Despite the effectiveness of endocrine therapies to treat estrogen receptor-positive (ER+) breast tumours, two thirds of patients will eventually relapse due to de novo or acquired resistance to these agents. Cancer Stem-like Cells (CSCs), a rare cell population within the tumour, accumulate after anti-estrogen treatments and are likely to contribute to their failure. Here we studied the role of p21-activated kinase 4 (PAK4) as a promising target to overcome endocrine resistance and disease progression in ER+ breast cancers. PAK4 predicts for resistance to tamoxifen and poor prognosis in 2 independent cohorts of ER+ tumours. We observed that PAK4 strongly correlates with CSC activity in metastatic patient-derived samples irrespective of breast cancer subtype. However, PAK4-driven mammosphere-forming CSC activity increases alongside progression only in ER+ metastatic samples. PAK4 activity increases in ER+ models during acquired resistance to endocrine therapies. Targeting PAK4 with either CRT PAKi, a small molecule inhibitor of PAK4, or with specific siRNAs abrogates CSC activity/self-renewal in clinical samples and endocrine-resistant cells. Together, our findings establish that PAK4 regulates stemness during disease progression and that its inhibition reverses endocrine resistance in ER+ breast cancers. HighlightsO_LIPAK4 predicts for failure of endocrine therapies and poor prognosis C_LIO_LIPAK4 drives stemness and progression in ER+ metastatic breast cancer C_LIO_LITargeting PAK4 abrogates breast CSC activity and restores sensitivity to endocrine treatments C_LIO_LITargeting PAK4 will improve outcome of ER+ breast cancer patients C_LI List of Abbreviations that appeared in abstractCancer Stem-like Cells (CSCs) p21-activated kinase 4 (PAK4) Estrogen Receptor (ER)

cancer biology↗