Biology subjects

Nobre, A. R.

Publications and source records attributed to Nobre, A. R..

4 recordsLinked to original sources

bioRxiv2021

Epigenetic reprogramming of DCCs into dormancy suppresses metastasis via restored TGFβ-SMAD4 signaling.

Disseminated cancer cells (DCCs) identified in secondary organs, sometimes before the primary tumor becomes detectable and treated, can remain dormant for years to decades before manifesting. Microenvironmental and epigenetic mechanisms may control the onset and escape from dormancy, and here we reveal how a combination of the DNA methylation inhibitor 5-azacytidine (AZA) and retinoic acid receptor ligands all-trans retinoic acid (atRA), orchestrate a novel program of stable dormancy. Treatment of HNSCC tumor cells with AZA+atRA induced a SMAD2/3/4 dependent regulation of downstream transcriptional program that restored the anti-proliferative function of TGF{beta} signaling. Significantly, AZA+atRA or AZA+AM80, an RAR specific agonist, strongly suppresses lung metastasis formation. The metastatic suppression occurs via the induction and maintenance of phenotypically homogenous dormant SMAD4+/NR2F1+ non-proliferative DCCs. These findings suggest that strategies that maintain or induce dormancy programs may be a viable alternative strategy to improve patient outcomes by preventing or significantly delaying metastasis development.

cancer biology↗

bioRxiv2021

PERK inhibition blocks metastasis initiation by limiting UPR-dependent survival of dormant disseminated cancer cells

The unfolded protein response (UPR) kinase PERK has been shown to serve as a survival factor for HER2-driven breast and prostate cancers as well as for dormant cancer cells. However, its role in metastasis is not understood. Here we found in the MMTV-HER2 mouse model that quiescent HER2+ disseminated cancer cells (DCCs) displayed unresolved ER stress as revealed by high expression of the PERK-inducible GADD34 gene. Single cell gene expression profiling and imaging confirmed that a significant proportion of DCCs in lungs were dormant and displayed an active UPR. In human breast cancer metastasis biopsies, GADD34 expression and quiescence were also positively correlated. Importantly, PERK inhibition with a specific inhibitor (HC4) blunted metastasis development by selectively killing UPRhigh quiescent but not proliferative DCCs. We also show that PERK inhibition altered optimal HER2 activity in primary tumors as a result of sub-optimal HER2 trafficking and phosphorylation in response to EGF. Our data identify PERK as a unique "Achilles heel" in dormant DTCs, supporting a requisite role for PERK in DTCs. Taken together, these data identify novel strategies to eliminate quiescent DCCs in patients with disseminated cancer disease.

cancer biology↗

bioRxiv2021

A specific agonist of the orphan nuclear receptor NR2F1 suppresses metastasis through the induction of cancer cell dormancy

AO_SCPLOWBSTRACTC_SCPLOWDisseminated tumor cells (DTCs) in secondary organs often remain dormant for a long period of time before re-awakening and growing into overt metastases. We have previously identified NR2F1/COUP-TF1, an orphan nuclear receptor, as a master regulator of tumor cell dormancy in head and neck squamous cell carcinoma (HNSCC) and other cancer types. Here we describe the identification and function of a novel NR2F1 agonist herein referred to as compound 26 (C26). C26 was found to specifically activate NR2F1 in HNSCC cells, leading to increased NR2F1 transcription and nuclear protein accumulation. C26-mediated activation of NR2F1 induced growth arrest of HNSCC PDX line and cell lines in 3D cultures in vitro and on chicken embryo chorioallantoic membrane (CAM) in vivo. The effect of C26 on growth arrest was lost when NR2F1 was knocked out by CRISPR/Cas9. C26-induced growth arrest was mediated by activation of an NR2F1-regulated dormancy program, including upregulation of cyclin-dependent kinase (CDK) inhibitor p27 and the transcription factors retinoic acid receptor {beta} (RAR{beta}) and Sox9. In mice bearing HNSCC PDX tumors, combined adjuvant and neo-adjuvant treatment with C26 resulted in complete inhibition of lethal lung metastasis. Mechanistic analysis showed that lung DTCs in C26-treated mice displayed an NR2F1hi/p27hi/Ki-67lo phenotype, which kept them dormant in a single-cell state preventing their outgrowth into overt metastases. Our work reveals a novel NR2F1 agonist and provides a proof of principle strategy supporting that inducing DTC dormancy using NR2F1 agonists could be used as a therapeutic strategy to prevent metastasis.

cancer biology↗

bioRxiv2020

NG2+/Nestin+ mesenchymal stem cells dictate DTC dormancy in the bone marrow through TGFβ2

In the bone marrow (BM) microenvironment, NG2+/Nestin+ mesenchymal stem cells (MSCs) promote hematopoietic stem cell (HSC) quiescence1,2. Importantly, the BM can also harbour disseminated tumour cells (DTCs) from multiple cancers, which, like HSCs, can remain dormant3. The BM signals are so growth-restrictive that dormant BM DTCs can persist for years to decades only to awaken and fuel lethal metastasis3-10. The mechanisms and niche components regulating DTC dormancy remain largely unknown. Here, we reveal that periarteriolar BM-resident NG2+/Nestin+ MSCs can instruct breast cancer (BC) DTCs to enter dormancy. NG2+/Nestin+ MSCs produce TGF{beta}2 and BMP7 and activate a quiescence pathway dependent on TGFBRIII and BMPRII, which via p38-kinase result in p27-CDK inhibitor induction. Importantly, genetic depletion of the NG2+/Nestin+ MSCs or conditional knock-out of TGF{beta}2 in the NG2+/Nestin+ MSCs led to awakening and bone metastatic expansion of otherwise dormant p27+/Ki67- DTCs. Our results provide a direct proof that HSC dormancy niches control BC DTC dormancy. Given that aged NG2+/Nestin+ MSCs can lose homeostatic control of HSC dormancy, our results suggest that aging or extrinsic factors that affect the NG2+/Nestin+ MSC niche may result in a break from dormancy and BC bone relapse.

cancer biology↗