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Raghavendra Tk Poluri, Virginie Paquette, Éric P Allain, Camille Lafront, Charles Joly-Beauparlant, Cindy Weidmann, Arnaud Droit, Chantal Guillemette, Martin Pelletier, and Etienne Audet-Walsh

Prostate cancer (PCa) cells rely on the androgen receptor (AR) signaling axis to reprogram metabolism to sustain aberrant proliferation. Whether additional transcription factors participate to this reprogramming remains mostly unknown. To identify such factors, DNA motif analyses were performed in the promoter and regulatory regions of genes sensitive to androgens in PCa cells. These analyses identified two transcription factors, KLF5 and NFYA, as possibly associated with PCa cell metabolism. In clinical datasets, KLF5 and NFYA expression levels were associated with disease aggressiveness, being significantly decreased and increased, respectively, during PCa progression. Their expression was next investigated by qPCR and Western blot in human PCa cell models, revealing a positive regulation of KLF5 by androgens and a correlation between NFYA and AR protein expression status. siRNA-mediated knockdown of KLF5 increased human PCa cell proliferation rates in an AR-positive cell models, suggesting a tumor suppressor function. Live-cell metabolic assays showed that knockdown of KLF5 promoted mitochondrial respiration, a key metabolic pathway associated with PCa progression. The opposite was observed for knockdown of NFYA regarding proliferation and respiration, indicative of oncogenic characteristics. RNA-seq analyses following knockdown of either KLF5 and NFYA confirmed that both factors regulated distinct metabolic gene signatures, as well as other gene signatures, explaining their differential impact on PCa cell proliferation and metabolism. Overall, our findings identify KLF5 and NFYA as novel regulators of PCa cell metabolism.

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Lisa K Philp, Anja Rockstroh, Martin C Sadowski, Atefeh Taherian Fard, Melanie Lehman, Gregor Tevz, Michelle S Libério, Charles L Bidgood, Jennifer H Gunter, Stephen McPherson, Nenad Bartonicek, John D Wade, Laszlo Otvos Jr, and Colleen C Nelson

Hyperleptinemia is a well-established therapeutic side-effect of drugs inhibiting the androgen axis in prostate cancer (PCa), including main stay androgen deprivation therapy (ADT) and androgen targeted therapies (ATT). Given significant crossover between the adipokine hormone signalling of leptin and multiple cancer-promoting hallmark pathways, including growth, proliferation, migration, angiogenesis, metabolism and inflammation, targeting the leptin axis is therapeutically appealing, especially in advanced PCa where current therapies fail to be curative. In this study we uncover leptin as a novel universal target in PCa, and are the first to highlight increased intratumoural leptin and leptin receptor (LEPR) expression in PCa cells and patient tumours exposed to androgen deprivation, as is observed in patient tumours of metastatic and castrate resistant (CRPC) PCa. We also reveal world-first preclinical evidence that demonstrates marked efficacy of targeted leptin signalling blockade, using Allo-aca, a potent, specific, and safe LEPR peptide antagonist. Allo-aca suppressed tumour growth and delayed progression to CRPC in mice bearing LNCaP xenografts, with reduced tumour vascularity and altered pathways of apoptosis, transcription/translation, and energetics in tumours determined as potential mechanisms underpinning anti-tumour efficacy. We highlight LEPR blockade in combination with androgen axis inhibition represents a promising new therapeutic strategy vital in advanced PCa treatment.

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Zhi-yuan Pang, Yun-tao Wei, Mu-yan Shang, Shuang Li, Yang Li, Quan-xiu Jin, Zhi-xuan Liao, Ming-ke Cui, Xiao-yan Liu, and Qiang Zhang

Aberrant leptin signaling and overexpression of fibroblast growth factor receptor 1 (FGFR1) are both implicated in the pathogenesis of letrozole resistance in breast cancer (BCa), but it remains unknown whether these two pathways are involved in letrozole resistance in a coordinated manner. Here, we demonstrate that expression levels of the pre-B-cell leukemia homeobox transcription factor 3 (PBX3), a pioneer factor that governs divergent biological processes, were significantly upregulated in letrozole-resistant BCa cells and tissues, and this upregulation correlated to a poorer progression-free survival in patients. By leveraging a patient-derived xenograft model with pharmacological approaches, we demonstrated that leptin activated PBX3 expression in a STAT3 (signal transducer and activator of transcription 3)-dependent manner. Our loss- and gain-of-function study further showed that PBX3 attenuated response to letrozole by potentiating BCa cell survival and anchorage-independent growth in BCa cells. By profiling BCa cells with ectopic PBX3 expression, we revealed that PBX3 conferred letrozole resistance via transactivation of the FGFR1 signaling, and this molecular event must coordinate a synergistic transcription activation programs through interacting with MTA1-HDAC2 (metastasis-associated 1-histone deacetylase 2) complex. Overall, the available data reveal a novel role of leptin/PBX3 cascade linking energy homeostasis (i.e. hyperleptinemia) and endocrine therapy failure (i.e. letrozole resistance) in BCa.

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Patricia Borges de Souza and Chris McCabe

Radioiodine (RAI) therapy has been used to treat thyroid diseases for around 80 years, and yet it is only relatively recently that we are beginning to manipulate its use, as we understand more of the cellular complexities which govern its success. From the benign nature of hyperthyroidism to malignant thyroid carcinomas and their metastases, RAI has profoundly changed the management of thyroid disorders. However, the complex journey which has elicited this simple therapy is worth exploring.

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Livia Lamartina, Nadège Anizan, Corinne Dupuy, Sophie Leboulleux, and Martin Schlumberger

Based on experimental data, the inhibition of the MAPkinase pathway in patients with radioiodine refractory thyroid cancer was capable to induce a redifferentiation. Preliminary data obtained on small series of patients are encouraging and this strategy might become an alternative treatment in those patients with a druggable mutation that induces a stimulation of the MAP kinase pathway. This is an active field of research to answer many still unresolved questions.

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Avaniyapuram Kannan Murugan, Abeer Al-Amr, Mysoon M Al-Ansari, Pulicat S. Manogaran, Hindi Al-Hindi, and Ali S Alzahrani

Thyroid cancer is a common endocrine neoplasm. Despite its good prognosis, it can lead to significant mortality due to metastasis and recurrence. However, the factors involved in metastasis are not well studied. Therefore, we selected matrix metalloproteinases 2 (MMP2) and determined whether it has any role in thyroid cancer. We sequenced the exons of MMP2 in 211 samples including 16 multi-nodular goiters and 195 differentiated thyroid cancers. We identified four non-synonymous single nucleotide polymorphisms (SNPs) of the MMP2 gene in 3.06% (6/195) thyroid cancers. Of the 4 MMP2 SNPs, 3 (75%) concomitantly had BRAFV600E. Hence, we speculated that the MMP2 SNPs may likely cooperate with BRAFV600E in promoting tumor aggressiveness. Overexpression of two MMP2 SNPs (P38L and T458I) exhibited markedly enhanced gelatinase activity with an intact dimerization and induced strong cortactin foci formation in HEK293T cells. Stable expression of the two MMP2 SNPs in BRAFV600E positive BCPAP cells dramatically enhanced cell proliferation, colony formation, and focus formation. Analysis of the morphology of MMP2 SNP bearing BCPAPV600E cells exhibited highly invasive phenotypes characterized by a high rate of wound healing and enhanced cell invasion compared with parental BCPAPV600E cells bearing vector. We also determined that BCPAPV600E cells stably transfected with MMP2 SNPs were highly sensitive to the treatment of BRAF inhibitor, PLX4720. Our study demonstrates that MMP2 SNPs could cooperate with BRAFV600E to promote oncogenicity, migration, and invasiveness of PTC cells. These results suggest that a subset of papillary thyroid cancer with this genetic makeup can benefit from BRAF-mediated therapeutic interventions.

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Mintallah Haider, Satya Das, Taymeyah Al-Toubah, Eleonora Pelle, Ghassan El-Haddad, and Jonathan Strosberg

Peptide receptor radionuclide therapy (PRRT) using 177Lu-DOTATATE has been approved for the treatment of gastroenteropancreatic NETs. An understanding of benefits and risks is important for the appropriate implementation of this therapy. This review summarizes study data supporting the use of radiolabeled somatostatin analogs for the treatment of advanced NETs and highlights risks, including potential toxicities in specific populations. Key ongoing clinical trials, including randomized studies, are designed to better define the position of PRRT within the broader therapeutic landscape. Preclinical and early-phase human studies are focused on the development of novel somatostatin-receptor agonists and antagonists, new radionuclides, and radiosensitizing combination therapies.

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James C Yao, Jonathan Strosberg, Nicola Fazio, Marianne E Pavel, Emily Bergsland, Philippe Ruszniewski, Daniel M Halperin, Daneng Li, Salvatore Tafuto, Nitya Raj, Davide Campana, Susumu Hijioka, Markus Raderer, Rosine Guimbaud, Pablo Gajate, Sara Pusceddu, Albert Reising, Evgeny Degtyarev, Mark Shilkrut, Simantini Eddy, and Simron Singh

Spartalizumab, a humanized anti-programmed death protein 1 (PD-1) MAB, was evaluated in patients with well-differentiated metastatic grade 1/2 neuroendocrine tumors (NET) and poorly differentiated gastroenteropancreatic neuroendocrine carcinomas (GEP-NEC). In this phase II, multicenter, single-arm study, patients received spartalizumab 400 mg every 4 weeks until confirmed disease progression or unacceptable toxicity. The primary endpoint was confirmed overall response rate (ORR) according to blinded independent review committee using response evaluation criteria in solid tumors 1.1. The study enrolled 95 patients in the NET group (30, 32 and 33 in the thoracic, gastrointestinal, and pancreatic cohorts, respectively), and 21 patients in the GEP-NEC group. The ORR was 7.4% (95% CI: 3.0, 14.6) in the NET group (thoracic, 16.7%; gastrointestinal, 3.1%; pancreatic, 3.0%), which was below the predefined success criterion of ≥10%, and 4.8% (95% CI: 0.1, 23.8) in the GEP-NEC group. In the NET and GEP-NEC groups, the 12-month progression-free survival was 19.5 and 0%, respectively, and the 12-month overall survival was 73.5 and 19.1%, respectively. The ORR was higher in patients with ≥1% PD-L1 expression in immune/tumor cells or ≥1% CD8+ cells at baseline. The most common adverse events considered as spartalizumab-related included fatigue (29.5%) and nausea (10.5%) in the NET group, and increased aspartate and alanine aminotransferases (each 14.3%) in the GEP-NEC group. The efficacy of spartalizumab was limited in this heterogeneous and heavily pre-treated population; however, the results in the thoracic cohort are encouraging and warrants further investigation. Adverse events were manageable and consistent with previous experience.