Jak2V617F Reversible Activation Shows Its Essential Requirement in Myeloproliferative Neoplasms

Gain-of-function mutations activating JAK/STAT signaling are seen in the majority of patients with myeloproliferative neoplasms (MPN), most commonly JAK2V617F. Although clinically approved JAK inhibitors improve symptoms and outcomes in MPNs, remissions are rare, and mutant allele burden does not substantively change with chronic therapy. We hypothesized this is due to limitations of current JAK inhibitors to potently and specifically abrogate mutant JAK2 signaling. We therefore developed a conditionally inducible mouse model allowing for sequential activation, and then inactivation, of Jak2V617F from its endogenous locus using a combined Dre-rox/Cre-lox dual-recombinase system. Jak2V617F deletion abrogates MPN features, induces depletion of mutant-specific hematopoietic stem/progenitor cells, and extends overall survival to an extent not observed with pharmacologic JAK inhibition, including when cooccurring with somatic Tet2 loss. Our data suggest JAK2V617F represents the best therapeutic target in MPNs and demonstrate the therapeutic relevance of a dual-recombinase system to assess mutant-specific oncogenic dependencies in vivo.

SIGNIFICANCE

Current JAK inhibitors to treat myeloproliferative neoplasms are ineffective at eradicating mutant cells. We developed an endogenously expressed Jak2V617F dual-recombinase knock-in/knock-out model to investigate Jak2V617F oncogenic reversion in vivo. Jak2V617F deletion abrogates MPN features and depletes disease-sustaining MPN stem cells, suggesting improved Jak2V617F targeting offers the potential for greater therapeutic efficacy. See related commentary by Celik and Challen, p. 701. This article is featured in Selected Articles from This Issue, p. 695.

Investigating strontium isotope linkage between biominerals (uroliths), drinking water and environmental matrices

This study presents the mineralogy and strontium isotope ratio (87Sr/86Sr) of 21 pathological biominerals (bladder and kidney stones) collected from patients admitted between 2018 and 2020 at the Department of Urology of the San Pio Hospital (Benevento, southern Italy). Urinary stones belong to the calcium oxalate, purine or calcium phosphate mineralogy types. Their corresponding 87Sr/86Sr range from 0.707607 for an uricite sample to 0.709970 for a weddellite one, and seem to be partly discriminated based on the mineralogy. The comparison with the isotope characteristics of 38 representative Italian bottled and tap drinking waters show a general overlap in 87Sr/86Sr with the biominerals. However, on a smaller geographic area (Campania Region), we observe small 87Sr/86Sr differences between the biominerals and local waters. This may be explained by external Sr inputs for example from agriculture practices, inhaled aerosols (i.e., particulate matter), animal manure and sewage, non-regional foods. Nevertheless, biominerals of patients that stated to drink and eat local water/wines and foods every day exhibited a narrower 87Sr/86Sr range roughly matching the typical isotope ratios of local geological materials and waters, as well as those of archaeological biominerals from the same area. Finally, we conclude that the strontium isotope signature of urinary stones may reflect that of the environmental matrices surrounding patients, but future investigations are recommended to ultimately establish the potential for pathological biominerals as reliable biomonitoring proxies, taking into the account the contribution of the external sources of Sr.

MAVS signaling is required for preventing persistent chikungunya heart infection and chronic vascular tissue inflammation

Chikungunya virus (CHIKV) infection has been associated with severe cardiac manifestations, yet, how CHIKV infection leads to heart disease remains unknown. Here, we leveraged both mouse models and human primary cardiac cells to define the mechanisms of CHIKV heart infection. Using an immunocompetent mouse model of CHIKV infection as well as human primary cardiac cells, we demonstrate that CHIKV directly infects and actively replicates in cardiac fibroblasts. In immunocompetent mice, CHIKV is cleared from cardiac tissue without significant damage through the induction of a local type I interferon response from both infected and non-infected cardiac cells. Using mice deficient in major innate immunity signaling components, we found that signaling through the mitochondrial antiviral-signaling protein (MAVS) is required for viral clearance from the heart. In the absence of MAVS signaling, persistent infection leads to focal myocarditis and vasculitis of the large vessels attached to the base of the heart. Large vessel vasculitis was observed for up to 60 days post infection, suggesting CHIKV can lead to vascular inflammation and potential long-lasting cardiovascular complications. This study provides a model of CHIKV cardiac infection and mechanistic insight into CHIKV-induced heart disease, underscoring the importance of monitoring cardiac function in patients with CHIKV infections.

Establishment of patient-derived tumor organoids to functionally inform treatment decisions in metastatic colorectal cancer

BACKGROUND

Metastatic colorectal cancer (mCRC) patients tend to have modest benefits from molecularly driven therapeutics. Patient-derived tumor organoids (PDTOs) represent an unmatched model to elucidate tumor resistance to therapy, due to their high capacity to resemble tumor characteristics.

MATERIALS AND METHODS

We used viable tumor tissue from two cohorts of patients with mCRC, naïve or refractory to treatment, respectively, for generating PDTOs. The derived models were subjected to a 6-day drug screening assay (DSA) with a comprehensive pipeline of chemotherapy and targeted drugs against almost all the actionable mCRC molecular drivers. For the second cohort DSA data were matched with those from PDTO genotyping.

RESULTS

A total of 40 PDTOs included in the two cohorts were derived from mCRC primary tumors or metastases. The first cohort included 31 PDTOs derived from patients treated in front line. For this cohort, DSA results were matched with patient responses. Moreover, RAS/BRAF mutational status was matched with DSA cetuximab response. Ten out of 12 (83.3%) RAS wild-type PDTOs responded to cetuximab, while all the mutant PDTOs, 8 out of 8 (100%), were resistant. For the second cohort (chemorefractory patients), we used part of tumor tissue for genotyping. Four out of nine DSA/genotyping data resulted applicable in the clinic. Two RAS-mutant mCRC patients have been treated with FOLFOX-bevacizumab and mitomycin-capecitabine in third line, respectively, based on DSA results, obtaining disease control. One patient was treated with nivolumab-second mitochondrial-derived activator of caspases mimetic (phase I trial) due to high tumor mutational burden at genotyping, experiencing stable disease. In one case, the presence of BRCA2 mutation correlated with DSA sensitivity to olaparib; however, the patient could not receive the therapy.

CONCLUSIONS

Using CRC as a model, we have designed and validated a clinically applicable methodology to potentially inform clinical decisions with functional data. Undoubtedly, further larger analyses are needed to improve methodology success rates and propose suitable treatment strategies for mCRC patients.

ODP551 Halting ErbB-2 Isoforms Retrograde Transport to the Nucleus as a New Theragnostic Approach for Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) is clinically defined by the absence of estrogen and progesterone receptors and the lack of membrane overexpression or gene amplification of the receptor tyrosine kinase ErbB-2/HER2. Due to its heterogeneity, clinical biomarkers and targeted therapies for this disease remain elusive, and chemotherapy has been the standard of care for TNBC. ErbB-2 is classically located at the membrane of BC cells, where it triggers signaling cascades and promotes oncogenesis. We previously demonstrated that ErbB-2 is also localized in the nucleus (NErbB-2) of TNBC cells, from where it drives growth (1). We also discovered that TNBC expresses both wild-type ErbB-2 (WTErbB-2) and alternative ErbB-2 isoform c (ErbB-2c) (1). ErbB-2 migrates to the nucleus via retrograde transport. Here, we revealed that Retro-2, an inhibitor of retrograde transport that protects cells form the deleterious effects of toxins and viruses, evicts both WTErbB-2 and ErbB-2c from the nucleus of BC cells. Using BC models from several molecular subtypes, as well as normal breast cells, we demonstrated that Retro-2 specifically halts the proliferation of cells expressing NErbB-2. Moreover, Retro-2 decreased the expression of genes induced by NErbB-2 (i. e. cyclin D1 and Erk5) and promoted cell cycle arrest at G0/G1 phase and apoptosis. In addition to R2 growth inhibitory activity in vitro, we here also demonstrated that its optimized cyclic derivative Retro-2.1 (in particular the (S)-enantiomer) showed improved efficacy both to evict ErbB-2 isoforms from the nucleus and to inhibit proliferation in vitro. Importantly, Retro-2 eviction of both ErbB-2 isoforms from the nucleus resulted in a striking growth abrogation in multiple TNBC preclinical models, including xenografts and tumor explants). Our mechanistic studies demonstrated that Retro-2 induces a differential accumulation of WTErbB-2 at the early endosomes and plasma membrane, and of ErbB-2c at the Golgi, shedding light both on Retro-2 action on endogenous protein cargoes undergoing retrograde transport and on the biology of ErbB-2 splicing variants. Compelling evidence demonstrated that mRNAs 5' and 3' untranslated regions (UTRs) mediate post-transcriptional regulation of gene expression and determine protein levels and fate. While both T1 and T3 have different 5' but the same 3' UTRs sequences, our in silico studies showed that T1 and T3 RNA secondary structures vary in the region containing both their 5' and 3' UTRs. These findings suggest that T3 secondary structure impacts in its cell specific localization. Together, our present discoveries identify R2 as a precision oncology tool to target NErbB-2 retrograde transport. This novel theragnostic approach could greatly improve the outcome of TNBC patients. (1) Chervo MF et al, Oncogene 2020: 39: 6245-62.

Presentation: No date and time listed

May a comprehensive mineralogical study of a jackstone calculus and some other human bladder stones unveil health and environmental implications?

This paper represents the first result of an active collaboration between the University of Sannio and the San Pio Hospital (Benevento, Italy), started in the 2018, that aims to a detailed mineralogical investigation of urinary stones of patients from Campania region. Herein, selected human bladder stones have been deeply characterized for clinical purposes and environmental biomonitoring, focusing on the importance to evaluate the concentration and distribution of undesired trace elements by means of microscopic techniques in the place of conventional wet chemical analyses. A rare bladder stone with a sea-urchin appearance, known as jackstone calculus, were also investigated (along with bladder stones made of uric acid and brushite) by means a comprehensive analytical approach, including Synchrotron X-ray Diffraction and Simultaneous Thermal Analyses. Main clinical assumptions were inferred according to the morpho-constitutional classification of bladder stones and information about patient's medical history and lifestyle. In most of the analyzed uroliths, undesired trace elements such as copper, cadmium, lead, chromium, mercury and arsenic have been detected and generally attributable to environmental pollution or contaminated food. Simultaneous occurrence of selenium and mercury should denote a methylmercury detoxification process, probably leading to the formation of a very rare HgSe compound known as tiemannite.

Single-cell multi-omics of human clonal hematopoiesis reveals that DNMT3A R882 mutations perturb early progenitor states through selective hypomethylation

Somatic mutations in cancer genes have been detected in clonal expansions across healthy human tissue, including in clonal hematopoiesis. However, because mutated and wild-type cells are admixed, we have limited ability to link genotypes with phenotypes. To overcome this limitation, we leveraged multi-modality single-cell sequencing, capturing genotype, transcriptomes and methylomes in progenitors from individuals with DNMT3A R882 mutated clonal hematopoiesis. DNMT3A mutations result in myeloid over lymphoid bias, and an expansion of immature myeloid progenitors primed toward megakaryocytic-erythroid fate, with dysregulated expression of lineage and leukemia stem cell markers. Mutated DNMT3A leads to preferential hypomethylation of polycomb repressive complex 2 targets and a specific CpG flanking motif. Notably, the hypomethylation motif is enriched in binding motifs of key hematopoietic transcription factors, serving as a potential mechanistic link between DNMT3A mutations and aberrant transcriptional phenotypes. Thus, single-cell multi-omics paves the road to defining the downstream consequences of mutations that drive clonal mosaicism.

Abstract 344: Blockade of retrograde transport in triple negative breast cancer excludes ErbB-2 isoforms from the nucleus and abrogates tumor growth

Triple negative breast cancer (TNBC) is clinically defined by the absence of estrogen and progesterone receptors and the lack of membrane overexpression or gene amplification of the receptor tyrosine kinase ErbB-2/HER2. Due to its heterogeneity, clinical biomarkers and targeted therapies for this disease remain elusive, and chemotherapy has been the standard of care for early and metastatic TNBC. ErbB-2 is classically located at the membrane of BC cells, where it triggers signalling cascades and promotes oncogenesis. However, we have demonstrated that ErbB-2 is also localized in the nucleus (NErbB-2) of TNBC cells and primary tumors, from where it drives growth. We also discovered that TNBC expresses both wild-type ErbB-2 (WTErbB-2) and alternative ErbB-2 isoform c (ErbB-2c). ErbB-2 migrates to the nucleus via retrograde transport. The small molecule Retro-2 is a non-toxic inhibitor of the retrograde transport route that protects cells from the deleterious effects of toxins and viruses. Here, we revealed that Retro-2 evicts both WTErbB-2 and ErbB-2c from the nuclei. Using BC models from several molecular subtypes, we demonstrated that Retro-2 specifically halts the proliferation of cells expressing NErbB-2 in a dose-dependent manner, whilst did not inhibit cell proliferation in the ErbB-2-negative MCF10A normal breast cell line. Additionally, Retro-2 decreased the expression of genes induced by NErbB-2 (cyclin D1 and Erk5) and promoted cell cycle arrest at G0/G1 phase and apoptosis. Even more, in preclinical models (including xenografts and tumor explants), Retro-2 treatment resulted in the eviction of NErbB-2 and abrogation of tumor growth. Our mechanistic studies demonstrated that Retro-2 induces a differential accumulation of WTErbB-2 at the early endosomes and plasma membrane, and of ErbB-2c at the Golgi, further preventing its sorting to the endoplasmic reticulum. These findings shed light both on Retro-2 action on endogenous protein cargoes undergoing retrograde transport and on the biology of ErbB-2 splicing variants. Together, our present discoveries provide evidence for the rational repurposing of Retro-2 as a novel therapeutic agent for TNBC.

Citation Format: Santiago Madera, Franco Izzo, Maria F. Chervo, Agustina Dupont, Violeta A. Chiauzzi, Sofia Bruni, Ezequiel Petrillo, Diego Montero, Sharon Merin, Maria F. Mercogliano, Cecilia J. Proietti, Roxana Schillaci, Rosalia I. Cordo Russo, Patricia V. Elizalde. Blockade of retrograde transport in triple negative breast cancer excludes ErbB-2 isoforms from the nucleus and abrogates tumor growth [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 344.

Halting ErbB-2 isoforms retrograde transport to the nucleus as a new theragnostic approach for triple-negative breast cancer

Triple-negative breast cancer (TNBC) is clinically defined by the absence of estrogen and progesterone receptors and the lack of membrane overexpression or gene amplification of receptor tyrosine kinase ErbB-2/HER2. Due to TNBC heterogeneity, clinical biomarkers and targeted therapies for this disease remain elusive. We demonstrated that ErbB-2 is localized in the nucleus (NErbB-2) of TNBC cells and primary tumors, from where it drives growth. We also discovered that TNBC expresses both wild-type ErbB-2 (WTErbB-2) and alternative ErbB-2 isoform c (ErbB-2c). Here, we revealed that the inhibitors of the retrograde transport Retro-2 and its cyclic derivative Retro-2.1 evict both WTErbB-2 and ErbB-2c from the nucleus of BC cells and tumors. Using BC cells from several molecular subtypes, as well as normal breast cells, we demonstrated that Retro-2 specifically blocks proliferation of BC cells expressing NErbB-2. Importantly, Retro-2 eviction of both ErbB-2 isoforms from the nucleus resulted in a striking growth abrogation in multiple TNBC preclinical models, including tumor explants and xenografts. Our mechanistic studies in TNBC cells revealed that Retro-2 induces a differential accumulation of WTErbB-2 at the early endosomes and the plasma membrane, and of ErbB-2c at the Golgi, shedding new light both on Retro-2 action on endogenous protein cargoes undergoing retrograde transport, and on the biology of ErbB-2 splicing variants. In addition, we revealed that the presence of a functional signal peptide and a nuclear export signal (NES), both located at the N-terminus of WTErbB-2, and absent in ErbB-2c, accounts for the differential subcellular distribution of ErbB-2 isoforms upon Retro-2 treatment. Our present discoveries provide evidence for the rational repurposing of Retro-2 as a novel therapeutic agent for TNBC.

Specification of fetal liver endothelial progenitors to functional zonated adult sinusoids requires c-Maf induction

The liver vascular network is patterned by sinusoidal and hepatocyte co-zonation. How intra-liver vessels acquire their hierarchical specialized functions is unknown. We study heterogeneity of hepatic vascular cells during mouse development through functional and single-cell RNA-sequencing. The acquisition of sinusoidal endothelial cell identity is initiated during early development and completed postnatally, originating from a pool of undifferentiated vascular progenitors at E12. The peri-natal induction of the transcription factor c-Maf is a critical switch for the sinusoidal identity determination. Endothelium-restricted deletion of c-Maf disrupts liver sinusoidal development, aberrantly expands postnatal liver hematopoiesis, promotes excessive postnatal sinusoidal proliferation, and aggravates liver pro-fibrotic sensitivity to chemical insult. Enforced c-Maf overexpression in generic human endothelial cells switches on a liver sinusoidal transcriptional program that maintains hepatocyte function. c-Maf represents an inducible intra-organotypic and niche-responsive molecular determinant of hepatic sinusoidal cell identity and lays the foundation for the strategies for vasculature-driven liver repair.

Radiological assessment of peritoneal carcinomatosis: a primer for resident

The imaging has critical responsibility in the assessment of peritoneal lesions along with estimating the overall extent. Valuing disease burden is crucial for selection of combining cytoreductive surgery (CRS) and intraperitoneal hyperthermic chemotherapy (HIPEC) treatment. An approach that combines the strength of several imaging tools and increases diagnostic accuracy, should be chosen, even if the preferred imaging tool in patients with suspected Peritoneal Carcinomatosis (PC) is CT. The outcomes of PC are mainly correlated to tumor spread, localization, and lesion size. Accurate assessment of these features is critical for prognosis and treatment planning. These data can be evaluated by Peritoneal Cancer Index (PCI), a quantitative index suggested by Harman and Sugarbaker. Additionally, precise predictive biomarkers should be established to predict PC in patients at risk. The radiomics analysis could predict PC throughout the evaluation of cancers heterogeneity.

Diagnostic performance of LI-RADS in adult patients with rare hepatic tumors

OBJECTIVE

The rare hepatic tumor can have a wide spectrum of radiologic features, representing a diagnostic challenge. Our purpose is to report the experience of a National Cancer Center, emphasizing the radiological features encountered and assessing the LR-M categories in the diagnostic performances for these lesions.

PATIENTS AND METHODS

We assessed 113 patients who underwent surgical resection or biopsy for rare liver lesions from May 2010 to December 2020. For these patients a computerized search of radiological records was performed to identify which had been studied with MRI and CT. For each lesion, the radiologists recorded the attenuation on CT studies and signal intensity (SI) in T1 weighted (W), in T2-W, DWI and in the related map of the apparent diffusion coefficient (ADC). We assessed the presence and the type of contrast enhancement (CE) during contrast study on CT and MRI and the enhancement was categorized according to LI-RADS 2018. We also assessed the presence of other features in LR-M categories (ancillary LR-M features) in order to classify different subgroups. The lesions were classified according to LR categories, and the gold standard was histological analysis.

RESULTS

The final study population included 95 patients (46 females and 49 males), with a mean age of 51 years (range 38-83 years). 83 patients had solid lesions, 12 patients had cystic lesions (simple or complex). According to histological analysis, we categorized 79 patients with malignant lesions and 16 patients with benign lesions. According to radiological features we assessed as malignant 82 patients (79 true malignant and 3 false malignant), as benign 13 patients (all true benign). Therefore, sensitivity, specificity, positive predictive value, negative predictive value and accuracy of radiological features to identify benign and malignant lesions were 100.0%, 81.3%, 96.3%, 100.0% and 96.8%, respectively. We found no significant difference in signal and contrast enhancement appearance among all LR-M categories (p-value =0.34 at Chi square test). However, among LR-M categories the presence of satellite nodules was a feature typical of cHCC-CC (p-value < 0.05 at Chi square test). The presence of intra lesion necrosis and haemorrhage was suggestive of sarcoma (p-value < 0.05 at Chi square test).

CONCLUSIONS

High diagnostic accuracy was obtained by LI-RADS classification between malignant and benign lesion. The presence of ancillary features could help the radiologist towards a correct diagnosis.

Non-thyroidal illness syndrome and SARS-CoV-2-associated multisystem inflammatory syndrome in children

PURPOSE

COVID-19 disease may result in a severe multisystem inflammatory syndrome in children (MIS-C), which in turn may alter thyroid function (TF). We assessed TF in MIS-C, evaluating its impact on disease severity.

METHODS

We retrospectively considered children admitted with MIS-C to a single pediatric hospital in Milan (November 2019-January 2021). Non-thyroidal illness syndrome (NTIS) was defined as any abnormality in TF tests (FT3, FT4, TSH) in the presence of critical illness and absence of a pre-existing hormonal abnormality. We devised a disease severity score by combining severity scores for each organ involved. Glucose and lipid profiles were also considered. A principal component analysis (PCA) was performed, to characterize the mutual association patterns between TF and disease severity.

RESULTS

Of 26 (19 M/7F) patients, median age 10.7 (IQR 5.8-13.3) years, 23 (88.4%) presented with NTIS. A low FT3 level was noted in 15/23 (65.3%), while the other subjects had varying combinations of hormone abnormalities (8/23, 34.7%). Mutually correlated variables related to organ damage and inflammation were represented in the first dimension (PC1) of the PCA. FT3, FT4 and total cholesterol were positively correlated and characterized the second axis (PC2). The third axis (PC3) was characterized by the association of triglycerides, TyG index and HDL cholesterol. TF appeared to be related to lipemic and peripheral insulin resistance profiles. A possible association between catabolic components and severity score was also noted.

CONCLUSIONS

A low FT3 level is common among MIS-C. TF may be useful to define the impact of MIS-C on children's health and help delineate long term follow-up management and prognosis.

Epigenetic encoding, heritability and plasticity of glioma transcriptional cell states

Single-cell RNA sequencing has revealed extensive transcriptional cell state diversity in cancer, often observed independently of genetic heterogeneity, raising the central question of how malignant cell states are encoded epigenetically. To address this, here we performed multiomics single-cell profiling-integrating DNA methylation, transcriptome and genotype within the same cells-of diffuse gliomas, tumors characterized by defined transcriptional cell state diversity. Direct comparison of the epigenetic profiles of distinct cell states revealed key switches for state transitions recapitulating neurodevelopmental trajectories and highlighted dysregulated epigenetic mechanisms underlying gliomagenesis. We further developed a quantitative framework to directly measure cell state heritability and transition dynamics based on high-resolution lineage trees in human samples. We demonstrated heritability of malignant cell states, with key differences in hierarchal and plastic cell state architectures in IDH-mutant glioma versus IDH-wild-type glioblastoma, respectively. This work provides a framework anchoring transcriptional cancer cell states in their epigenetic encoding, inheritance and transition dynamics.

Liver resection and ablation for squamous cell carcinoma liver metastases

Background

Limited evidence exists to guide the management of patients with liver metastases from squamous cell carcinoma (SCC). The aim of this retrospective multicentre cohort study was to describe patterns of disease recurrence after liver resection/ablation for SCC liver metastases and factors associated with recurrence-free survival (RFS) and overall survival (OS).

Method

Members of the European–African Hepato-Pancreato-Biliary Association were invited to include all consecutive patients undergoing liver resection/ablation for SCC liver metastases between 2002 and 2019. Patient, tumour and perioperative characteristics were analysed with regard to RFS and OS.

Results

Among the 102 patients included from 24 European centres, 56 patients had anal cancer, and 46 patients had SCC from other origin. RFS in patients with anal cancer and non-anal cancer was 16 and 9 months, respectively (P = 0.134). A positive resection margin significantly influenced RFS for both anal cancer and non-anal cancer liver metastases (hazard ratio 6.82, 95 per cent c.i. 2.40 to 19.35, for the entire cohort). Median survival duration and 5-year OS rate among patients with anal cancer and non-anal cancer were 50 months and 45 per cent and 21 months and 25 per cent, respectively. For the entire cohort, only non-radical resection was associated with worse overall survival (hazard ratio 3.21, 95 per cent c.i. 1.24 to 8.30).

Conclusion

Liver resection/ablation of liver metastases from SCC can result in long-term survival. Survival was superior in treated patients with liver metastases from anal versus non-anal cancer. A negative resection margin is paramount for acceptable outcome.

Current status on response to treatment in locally advanced rectal cancer: what the radiologist should know

The assessment of tumor response, after neoadjuvant radiochemotherapy (nCRT), allows stratifying the patient in order to consider the proper therapeutical management. Histopathology analysis of the surgical specimen is considered the gold standard to assess tumour response and the definition of a complete cancer response is related to the clinical and endoscopic features, by direct evaluation of the rectal wall. However, imaging studies, especially Magnetic Resonance Imaging (MRI) have provided additional parameters, as the evaluation of nodal or mesorectal status. MRI provides a radiological tumour regression grade (mrTRG) that is correlated with the pathologic tumor regression grade (pTRG). Functional MRI parameters have additional impending in early prediction of the efficacy of therapy and can be valuable in drug development processes. Some of functional methodologies are already part of clinical practice: diffusion-weighted MRI (DW-MRI) and perfusion imaging (dynamic contrast enhanced MRI [DCE-MRI]). Other technologies, such as radiomics with MRI are still in the experimental phase. An adequate radiological report describing the restaging of rectal cancer after nCRT should be a "structured report" to improve communication in a multidisciplinary team.

Acute Myeloid Leukemia iPSCs Reveal a Role for RUNX1 in the Maintenance of Human Leukemia Stem Cells

Leukemia stem cells (LSCs) are believed to have more distinct vulnerabilities than the bulk acute myeloid leukemia (AML) cells, but their rarity and the lack of universal markers for their prospective isolation hamper their study. We report that genetically clonal induced pluripotent stem cells (iPSCs) derived from an AML patient and characterized by exceptionally high engraftment potential give rise, upon hematopoietic differentiation, to a phenotypic hierarchy. Through fate-tracking experiments, xenotransplantation, and single-cell transcriptomics, we identify a cell fraction (iLSC) that can be isolated prospectively by means of adherent in vitro growth that resides on the apex of this hierarchy and fulfills the hallmark features of LSCs. Through integrative genomic studies of the iLSC transcriptome and chromatin landscape, we derive an LSC gene signature that predicts patient survival and uncovers a dependency of LSCs, across AML genotypes, on the RUNX1 transcription factor. These findings can empower efforts to therapeutically target AML LSCs.

Halting Retrograde Transport Excludes ErbB-2 From the Nucleus Abrogating Tumor Growth in Triple Negative Breast Cancer

Triple negative breast cancer (TNBC) refers to a subtype of tumors with poor prognosis, devoid of hormone receptors and of membrane overexpression or gene amplification of ErbB-2. Due to its molecular heterogeneity, TNBC represents a major clinical challenge. In this regard, clinical biomarkers and targeted therapies remain elusive, and chemotherapy has been the standard of care for early and metastatic TNBC. ErbB-2, a member of the ErbB family of tyrosine kinase receptors, is a major player in the BC scenario. While it is a cell membrane-bound receptor, it migrates to the nucleus (NErbB-2) where it acts as a transcription factor or coactivator. We recently found that both the canonical (wild-type, WT) ErbB-2 and the alternative isoform c are located in the nucleus of TNBC, a scenario with an aggressive oncogenic potential. The route of intracellular transport from the plasma membrane to the trans Golgi network (TGN) and the endoplasmic reticulum (ER) is termed retrograde trafficking, and constitutes the pathway by which ErbB-2 migrates to the nucleus. The retrograde transport route is also hijacked by toxins and viruses to access the ER and exert their deleterious effects. Retro-2, a small molecule inhibitor, was shown to protect cells from toxin and virus effects by blocking their retrograde trafficking. Given the high levels of NErbB-2 in TNBC cells, we explored whether treatment with Retro-2 modulates localization of ErbB-2 and proliferation in TNBC.

We found that Retro-2 treatment decreased the levels of both WT ErbB-2 and isoform c in the nucleus of TNBC cells demonstrating that Retro-2 effects are not limited to a particular ErbB-2 isoform. Indeed, immunofluorescence assays revealed accumulation of ErbB-2 in the Golgi after Retro-2 treatment further preventing its sorting to the ER. We previously demonstrated that growth factors induce ErbB-2 migration into the nucleus in ErbB-2-positive BC cells. Consistently, we observed that Retro-2 prevents growth factor-induced NErbB-2 in ErbB-2-positive BC cells. Retro-2 treatment resulted in a dose-dependent decrease in cell proliferation in a panel of TNBC cells, whilst did not inhibit cell proliferation in the ErbB-2-negative MCF10A normal breast cell line. Moreover, disruption of retrograde transport by Retro-2 decreased the expression of cell cycle related NErbB-2 target genes (i.e. Erk5 and cyclin D1) therefore inducing cell cycle arrest at the G0/G1 phase. Most importantly, Retro-2 excluded ErbB-2 from the nucleus and abrogated tumor growth in preclinical models of TNBC.

Collectively, our findings reveal Retro-2, a non-toxic inhibitor of the retrograde transport route, as a candidate novel therapeutic agent for TNBC based on its ability to evict ErbB-2 from the nucleus and to abrogate TNBC growth.

Beyond the vascular profile: conventional DWI, IVIM and kurtosis in the assessment of hepatocellular carcinoma

OBJECTIVE

To describe the role of the Diffusion Weighted Imaging (DWI) in the assessment of hepatocellular carcinoma (HCC).

MATERIALS AND METHODS

Several electronic databases were evaluated in the present review. The search included articles published from January 2010 to May 2019. The references of all articles were also evaluated. All titles and abstracts were assessed, and only the studies of DWI in patients with HCC were retained.

RESULTS

HCC is the most common primitive hepatic cancer. The non-invasive radiological criteria for HCC diagnosis are based on the presence of the specific vascular profile characterized by contrast uptake during arterial phase, defined as arterial hyperenhancement, followed by washout in the venous/portal phase. However, arterial hyperenhancement and wash out appearance have a sensitivity rate of 50-60% in lesion smaller than 2 cm. Therefore, other functional parameters have been introduced in the detection and characterization of HCC nodules. DWI has been applied to liver imaging as an excellent tool for detection and characterization of focal liver lesions, increasing clinical confidence and decreasing false positives. The assessment of DW images can be done qualitatively and quantitatively, through the apparent diffusion coefficient (ADC) map. Intravoxel incoherent motion (IVIM) is a more sophisticated analysis, a biexponential model, to better defining the relationship between signal attenuation and increasing b value that separately reproduces tissue diffusivity and tissue perfusion. Traditionally DWI approach to analyze data is founded on the hypothesis that water molecules diffuse within a voxel following a single direction with a Gaussian behavior without any restriction. However, according to the presence of microstructures, water molecules within biologic tissues exhibits a non-Gaussian phenomena proposed by Jensen in 2005 called Diffusion Kurtosis Imaging (DKI). This approach assesses the kurtosis coefficient (K) that shows the deviance of diffusion from a Gaussian approach, and the diffusion coefficient (D) with the correction of non-Gaussian bias. DKI is an advanced DWI model that quantifies non-Gaussian behavior of diffusion and provides both a corrected ADC, as well as the excess kurtosis of tissue, a measure of the extent to which tissue diffusion deviates from a Gaussian pattern. It is believed that the DKI model is more sensitive to tissue microstructural complexity than standard DW.

CONCLUSIONS

DWI should be an integral part of study protocol for HCC patients, considering the great advantages due to DWI and DWI-based approaches in detection and characterization of HCC.

Electrochemotherapy of cholangiocellular carcinoma at hepatic hilum: a case report

OBJECTIVE

Cholangiocarcinoma (CCA) is the second most common primary hepatic malignancy after hepatocellular carcinoma. The current standard palliative treatment, chemotherapy regimen with gemcitabine and cisplatin, prolongs overall survival only of a few months. Established locoregional therapies are not a curative option or an alternative to surgery in the treatment of CCA. We report a case of a patient affected by a cholangiocellular carcinoma at hepatic hilum treated by Electrochemotherapy (ECT) at our oncologic center.

CASE PRESENTATION

A 71 years old male affected by a CCA at hepatic hilum was treated with ECT according to ESOPE guidelines. No complications occurred during ECT procedure. The patient was discharged after 10 days. The functional MR evaluation at 2 and at 4 months post-treatment showed a significant response without significant post-treatment adverse events. The Computed tomography (CT) assessment after 18 months did not show progression of disease.

CONCLUSIONS

ECT is safe and its use could be suggested as a palliative treatment of advanced neoplastic lesions in which radical surgical treatment is not possible.

Liver radiologic findings of chemotherapy-induced toxicity in liver colorectal metastases patients

There are a number of chemotherapy-effects that should be assessed with liver imaging since they have an influence on surgical morbidity. Chemotherapy-related complications, steatosis, chemotherapy-associated steatohepatitis (CASH), and SOS might impair the hepatic parenchyma, thus reducing the functionality and influencing the outcome following resection. The main role of a radiologist is to provide an accurate diagnosis of the lesion. With constant advances in medicine, a radiologist's role should extend beyond just reporting the data of tumor, providing additional information that may greatly improve patient care. Radiologists should assess both chemotherapy effects on the hepatic metastasis itself, as well as chemo-induced focal and diffuse modifications of non-tumor hepatic parenchyma, since it is important to avoid impaired hepatic function after hepatic resection.

EPCO-14. DECIPHERING DIFFERENTIATION HIERARCHIES, HERITABILITY AND PLASTICITY IN HUMAN GLIOMAS VIA SINGLE-CELL MULTI-OMICS

Human diffuse gliomas are incurable malignancies, where cellular state diversity fuels tumor progression and resistance to therapy. Single-cell RNA-sequencing (scRNAseq) studies recently charted the cellular states of the two major categories of human gliomas, IDH-mutant gliomas (IDH-MUT) and IDH-wildtype glioblastoma (GBM), showing that malignant cells partly recapitulate neurodevelopmental trajectories. This raises the central questions of how cell states are encoded epigenetically and whether unidirectional hierarchies or more plastic state transitions govern glioma cellular architectures. To address these questions, we generated multi-omics single-cell profiling, integrating DNA methylation (DNAme), transcriptome and genotyping of 1,728 cells from 11 GBM and IDH-MUT primary patient samples. Direct comparison of the methylomes of distinct glioma cell states revealed Polycomb repressive complex 2 (PRC2) targets DNAme as a key switch in the differentiation of malignant GBM cells. In contrast, dissecting aberrant circuits of hyper-methylation and gene expression in IDH-MUT gliomas, we observed a decoupling of the promoter methylation-expression relationship, with disruption of CTCF insulation and enhancer vulnerability which increases with cellular differentiation. To define cell state transition dynamics directly in patient samples, we generated high-resolution lineage histories of glioma cells using heritable DNAme changes, and projected the scRNAseq-derived cell states onto the lineage trees. This analysis demonstrated that cell states are heritable across malignant gliomas and, while in IDH-MUT differentiation far outpaces de-differentiation, GBM harbors a higher degree of cell state plasticity allowing reversion of GBM cells from a differentiated to a stem-like state. Overall, our work provides detailed insights into gliomagenesis, dissecting the epigenetic encoding, regulatory programs, and dynamics of the cellular states that drive human gliomas. Importantly, it also carries significant translational implication, as the high degree of de-differentiation in GBM challenges the paradigm of therapeutically targeting glioma stem-like cells to deprive tumors of their ability to regenerate.

Abstract PO-019: Deciphering differentiation hierarchies, heritability and plasticity in human gliomas via single-cell multi-omics

Human diffuse gliomas are incurable brain tumors, where cellular state diversity fuels tumor progression and resistance to therapy. Single-cell RNA-sequencing (scRNAseq) studies recently charted the cellular states of the two major categories of human gliomas, IDH-mutant gliomas (IDH-MUT) and IDH-wildtype glioblastoma (GBM), showing that malignant cells partly recapitulate neurodevelopmental trajectories. This raises the central questions of how cell states are encoded epigenetically and whether unidirectional hierarchies or more plastic state transitions govern glioma cellular architectures. To address these questions, we generated multi-omics single-cell profiling, integrating DNA methylation (DNAme), transcriptome and genotyping of 1,728 cells from 11 GBM and IDH-MUT primary patient samples. The assessment of DNAme intra-tumoral heterogeneity of malignant cells revealed that single-cell DNAme profiles within tumors span multiple bulk subtypes, are associated with important biological features of malignant cells, and may be confounded by the tumor micro-environment. Such sources of intra-tumoral heterogeneity in bulk profiles are important to recognize, as DNAme profiling is increasingly being utilized for bulk clinical brain tumor classification. The direct comparison of the methylomes of distinct glioma cellular states revealed Polycomb repressive complex 2 (PRC2) targets DNAme as a key switch in the differentiation of malignant GBM cells. In contrast, dissecting aberrant circuits of hypermethylation and gene expression in IDH-MUT gliomas, we observed a decoupling of the promoter methylation-expression relationship, with disruption of CTCF insulation and enhancer vulnerability which increases with cellular differentiation. To define cell state transition dynamics directly in patient samples, we generated high-resolution lineage histories of glioma cells using heritable DNAme changes, and projected the scRNAseq-derived cell states onto the lineage trees. This analysis demonstrated that cell states are heritable across malignant gliomas and, while in IDH-MUT differentiation far outpaces de-differentiation, GBM harbors a higher degree of cellular state plasticity allowing reversion of GBM cells from a differentiated to a stem-like state. Overall, our work provides detailed insights into gliomagenesis, dissecting the epigenetic encoding, regulatory programs, and dynamics of the cellular states that drive human gliomas. Importantly, it also carries significant translational implication, as the high degree of de-differentiation in GBM challenges the paradigm of therapeutically targeting glioma stem-like cells to deprive tumors of their ability to regenerate.

Citation Format: Federico Gaiti, Ronan Chaligne, Dana Silverbush, Joshua S. Schiffman, Hannah R. Weisman, Lloyd Kluegel, Simon Gritsch, Sunil D. Deochand, Alyssa R. Richman, Johanna Klughammer, Tommaso Biancalani, Christoph Muus, Caroline Sheridan, Alicia Alonso, Franco Izzo, Orit Rozenblatt-Rosen, Aviv Regev, Mario L. Suvà, Dan A. Landau. Deciphering differentiation hierarchies, heritability and plasticity in human gliomas via single-cell multi-omics [abstract]. In: Proceedings of the AACR Virtual Special Conference on Tumor Heterogeneity: From Single Cells to Clinical Impact; 2020 Sep 17-18. Philadelphia (PA): AACR; Cancer Res 2020;80(21 Suppl):Abstract nr PO-019.

m6A RNA Methylation Maintains Hematopoietic Stem Cell Identity and Symmetric Commitment

Stem cells balance cellular fates through asymmetric and symmetric divisions in order to self-renew or to generate downstream progenitors. Symmetric commitment divisions in stem cells are required for rapid regeneration during tissue damage and stress. The control of symmetric commitment remains poorly defined. Using single-cell RNA sequencing (scRNA-seq) in combination with transcriptomic profiling of HSPCs (hematopoietic stem and progenitor cells) from control and m⁶A methyltransferase Mettl3 conditional knockout mice, we found that m⁶A-deficient hematopoietic stem cells (HSCs) fail to symmetrically differentiate. Dividing HSCs are expanded and are blocked in an intermediate state that molecularly and functionally resembles multipotent progenitors. Mechanistically, RNA methylation controls Myc mRNA abundance in differentiating HSCs. We identified MYC as a marker for HSC asymmetric and symmetric commitment. Overall, our results indicate that RNA methylation controls symmetric commitment and cell identity of HSCs and may provide a general mechanism for how stem cells regulate differentiation fate choice.

Cheng et al. uncover RNA methylation as a guardian in hematopoietic stem cell (HSC) fate decisions. m⁶A maintains hematopoietic stem cell symmetric commitment and identity. This study may provide a general mechanism for how RNA methylation controls cellular fate.

DNA methylation disruption reshapes the hematopoietic differentiation landscape

Mutations in genes involved in DNA methylation (DNAme; for example, TET2 and DNMT3A) are frequently observed in hematological malignancies1-3 and clonal hematopoiesis4,5. Applying single-cell sequencing to murine hematopoietic stem and progenitor cells, we observed that these mutations disrupt hematopoietic differentiation, causing opposite shifts in the frequencies of erythroid versus myelomonocytic progenitors following Tet2 or Dnmt3a loss. Notably, these shifts trace back to transcriptional priming skews in uncommitted hematopoietic stem cells. To reconcile genome-wide DNAme changes with specific erythroid versus myelomonocytic skews, we provide evidence in support of differential sensitivity of transcription factors due to biases in CpG enrichment in their binding motif. Single-cell transcriptomes with targeted genotyping showed similar skews in transcriptional priming of DNMT3A-mutated human clonal hematopoiesis bone marrow progenitors. These data show that DNAme shapes the topography of hematopoietic differentiation, and support a model in which genome-wide methylation changes are transduced to differentiation skews through biases in CpG enrichment of the transcription factor binding motif.

EpiMethylTag: simultaneous detection of ATAC-seq or ChIP-seq signals with DNA methylation

Activation of regulatory elements is thought to be inversely correlated with DNA methylation levels. However, it is difficult to determine whether DNA methylation is compatible with chromatin accessibility or transcription factor (TF) binding if assays are performed separately. We developed a fast, low-input, low sequencing depth method, EpiMethylTag, that combines ATAC-seq or ChIP-seq (M-ATAC or M-ChIP) with bisulfite conversion, to simultaneously examine accessibility/TF binding and methylation on the same DNA. Here we demonstrate that EpiMethylTag can be used to study the functional interplay between chromatin accessibility and TF binding (CTCF and KLF4) at methylated sites.

Phase III randomized study of second line ADI-PEG 20 plus best supportive care versus placebo plus best supportive care in patients with advanced hepatocellular carcinoma

Background

Arginine depletion is a putative target in hepatocellular carcinoma (HCC). HCC often lacks argininosuccinate synthetase, a citrulline to arginine-repleting enzyme. ADI-PEG 20 is a cloned arginine degrading enzyme-arginine deiminase-conjugated with polyethylene glycol. The goal of this study was to evaluate this agent as a potential novel therapeutic for HCC after first line systemic therapy.

Methods and patients

Patients with histologically proven advanced HCC and Child-Pugh up to B7 with prior systemic therapy, were randomized 2 : 1 to ADI-PEG 20 18 mg/m2 versus placebo intramuscular injection weekly. The primary end point was overall survival (OS), with 93% power to detect a 4-5.6 months increase in median OS (one-sided α = 0.025). Secondary end points included progression-free survival, safety, and arginine correlatives.

Results

A total of 635 patients were enrolled: median age 61, 82% male, 60% Asian, 52% hepatitis B, 26% hepatitis C, 76% stage IV, 91% Child-Pugh A, 70% progressed on sorafenib and 16% were intolerant. Median OS was 7.8 months for ADI-PEG 20 versus 7.4 for placebo (P = 0.88, HR = 1.02) and median progression-free survival 2.6 months versus 2.6 (P = 0.07, HR = 1.17). Grade 3 fatigue and decreased appetite occurred in <5% of patients. Two patients on ADI-PEG 20 had ≥grade 3 anaphylactic reaction. Death rate within 30 days of end of treatment was 15.2% on ADI-PEG 20 versus 10.4% on placebo, none related to therapy. Post hoc analyses of arginine assessment at 4, 8, 12 and 16 weeks, demonstrated a trend of improved OS for those with more prolonged arginine depletion.

Conclusion

ADI-PEG 20 monotherapy did not demonstrate an OS benefit in second line setting for HCC. It was well tolerated. Strategies to enhance prolonged arginine depletion and synergize the effect of ADI-PEG 20 are underway.

Clinical Trial number

www.clinicaltrials.gov (NCT 01287585).

Somatic mutations and cell identity linked by Genotyping of Transcriptomes

Defining the transcriptomic identity of malignant cells is challenging in the absence of surface markers that distinguish cancer clones from one another, or from admixed non-neoplastic cells. To address this challenge, here we developed Genotyping of Transcriptomes (GoT), a method to integrate genotyping with high-throughput droplet-based single-cell RNA sequencing. We apply GoT to profile 38,290 CD34+ cells from patients with CALR-mutated myeloproliferative neoplasms to study how somatic mutations corrupt the complex process of human haematopoiesis. High-resolution mapping of malignant versus normal haematopoietic progenitors revealed an increasing fitness advantage with myeloid differentiation of cells with mutated CALR. We identified the unfolded protein response as a predominant outcome of CALR mutations, with a considerable dependency on cell identity, as well as upregulation of the NF-κB pathway specifically in uncommitted stem cells. We further extended the GoT toolkit to genotype multiple targets and loci that are distant from transcript ends. Together, these findings reveal that the transcriptional output of somatic mutations in myeloproliferative neoplasms is dependent on the native cell identity.

Differences in Blood Pressure in Infants After General Anesthesia Compared to Awake Regional Anesthesia (GAS Study-A Prospective Randomized Trial)

BACKGROUND

The General Anesthesia compared to Spinal anesthesia (GAS) study is a prospective randomized, controlled, multisite, trial designed to assess the influence of general anesthesia (GA) on neurodevelopment at 5 years of age. A secondary aim obtained from the blood pressure data of the GAS trial is to compare rates of intraoperative hypotension after anesthesia and to identify risk factors for intraoperative hypotension.

METHODS

A total of 722 infants ≤60 weeks postmenstrual age undergoing inguinal herniorrhaphy were randomized to either bupivacaine regional anesthesia (RA) or sevoflurane GA. Exclusion criteria included risk factors for adverse neurodevelopmental outcome and infants born at <26 weeks of gestation. Moderate hypotension was defined as mean arterial pressure measurement of <35 mm Hg. Any hypotension was defined as mean arterial pressure of <45 mm Hg. Epochs were defined as 5-minute measurement periods. The primary outcome was any measured hypotension <35 mm Hg from start of anesthesia to leaving the operating room. This analysis is reported primarily as intention to treat (ITT) and secondarily as per protocol.

RESULTS

The relative risk of GA compared with RA predicting any measured hypotension of <35 mm Hg from the start of anesthesia to leaving the operating room was 2.8 (confidence interval [CI], 2.0-4.1; P < .001) by ITT analysis and 4.5 (CI, 2.7-7.4, P < .001) as per protocol analysis. In the GA group, 87% and 49%, and in the RA group, 41% and 16%, exhibited any or moderate hypotension by ITT, respectively. In multivariable modeling, group assignment (GA versus RA), weight at the time of surgery, and minimal intraoperative temperature were risk factors for hypotension. Interventions for hypotension occurred more commonly in the GA group compared with the RA group (relative risk, 2.8, 95% CI, 1.7-4.4 by ITT).

CONCLUSIONS

RA reduces the incidence of hypotension and the chance of intervention to treat it compared with sevoflurane anesthesia in young infants undergoing inguinal hernia repair.

Percutaneous implant of Denver peritoneo-venous shunt for treatment of refractory ascites: a single center retrospective study

OBJECTIVE

Refractory ascites is defined as a lack of response to high doses of diuretics or the development of diuretic related side effects, which compel the patient to discontinue the diuretic treatment. Current therapeutic strategies include repeated large-volume paracentesis and transjugular intrahepatic portosystemic shunts (TIPS). Peritoneovenous shunt (Denver shunt) should be considered for patients with refractory ascites who are not candidates for paracentesis or TIPS. This study presents our case series in the implant of Denver peritoneovenous shunt.

PATIENTS AND METHODS

Sixty-two patients underwent percutaneous placement of Denver shunt between November 2003 and July 2014. There were 36 men and 26 women. Ascites was secondary to alcoholic cirrhosis in six patients, cryptogenic cirrhosis in six, and virus-related cirrhosis in fifty of them. Liver cirrhosis was classified as Child B in 22 patients and Child C in 40 (no patient was Child A).

RESULTS

All implants were successfully performed. There were no intraoperative problems or lethal complications; our patients were hospitalized for 2 or 3 days. Postoperative complications included: infection of the shunt in 3 patients (4.8%), shunt obstruction in 4 (6.4%) and transient abdominal pain in 4 (6.4%). Significant symptomatic relief was obtained in all patients.

CONCLUSIONS

The percutaneous placement of a Denver shunt is a technically feasible and effective method for symptomatic relief of refractory ascites.

MiR-16 mediates trastuzumab and lapatinib response in ErbB-2-positive breast and gastric cancer via its novel targets CCNJ and FUBP1

ErbB-2 amplification/overexpression accounts for an aggressive breast cancer (BC) subtype (ErbB-2-positive). Enhanced ErbB-2 expression was also found in gastric cancer (GC) and has been correlated with poor clinical outcome. The ErbB-2-targeted therapies trastuzumab (TZ), a monoclonal antibody, and lapatinib, a tyrosine kinase inhibitor, have proved highly beneficial. However, resistance to such therapies remains a major clinical challenge. We here revealed a novel mechanism underlying the antiproliferative effects of both agents in ErbB-2-positive BC and GC. TZ and lapatinib ability to block extracellular signal-regulated kinases 1/2 and phosphatidylinositol-3 kinase (PI3K)/AKT in sensitive cells inhibits c-Myc activation, which results in upregulation of miR-16. Forced expression of miR-16 inhibited in vitro proliferation in BC and GC cells, both sensitive and resistant to TZ and lapatinib, as well as in a preclinical BC model resistant to these agents. This reveals miR-16 role as tumor suppressor in ErbB-2-positive BC and GC. Using genome-wide expression studies and miRNA target prediction algorithms, we identified cyclin J and far upstream element-binding protein 1 (FUBP1) as novel miR-16 targets, which mediate miR-16 antiproliferative effects. Supporting the clinical relevance of our results, we found that high levels of miR-16 and low or null FUBP1 expression correlate with TZ response in ErbB-2-positive primary BCs. These findings highlight a potential role of miR-16 and FUBP1 as biomarkers of sensitivity to TZ therapy. Furthermore, we revealed miR-16 as an innovative therapeutic agent for TZ- and lapatinib-resistant ErbB-2-positive BC and GC.

Stat3 regulates ErbB-2 expression and co-opts ErbB-2 nuclear function to induce miR-21 expression, PDCD4 downregulation and breast cancer metastasis

Membrane overexpression of the receptor tyrosine kinase ErbB-2 (MErbB-2) accounts for a clinically aggressive breast cancer (BC) subtype (ErbB-2-positive) with increased incidence of metastases. We and others demonstrated that nuclear ErbB-2 (NErbB-2) also plays a key role in BC and is a poor prognostic factor in ErbB-2-positive tumors. The signal transducer and activator of transcription 3 (Stat3), another player in BC, has been recognized as a downstream mediator of MErbB-2 action in BC metastasis. Here, we revealed an unanticipated novel direction of the ErbB-2 and Stat3 interaction underlying BC metastasis. We found that Stat3 binds to its response elements (GAS) at the ErbB-2 promoter to upregulate ErbB-2 transcription in metastatic, ErbB-2-positive BC. We validated these results in several BC subtypes displaying metastatic and non-metastatic ability, highlighting Stat3 general role as upstream regulator of ErbB-2 expression in BC. Moreover, we showed that Stat3 co-opts NErbB-2 function by recruiting ErbB-2 as its coactivator at the GAS sites in the promoter of microRNA-21 (miR-21), a metastasis-promoting microRNA (miRNA). Using an ErbB-2 nuclear localization domain mutant and a constitutively activated ErbB-2 variant, we found that NErbB-2 role as a Stat3 coactivator and also its direct role as transcription factor upregulate miR-21 in BC. This reveals a novel function of NErbB-2 as a regulator of miRNAs expression. Increased levels of miR-21, in turn, downregulate the expression of the metastasis-suppressor protein programmed cell death 4 (PDCD4), a validated miR-21 target. Using an in vivo model of metastatic ErbB-2-postive BC, in which we silenced Stat3 and reconstituted ErbB-2 or miR-21 expression, we showed that both are downstream mediators of Stat3-driven metastasis. Supporting the clinical relevance of our results, we found an inverse correlation between ErbB-2/Stat3 nuclear co-expression and PDCD4 expression in ErbB-2-positive primary invasive BCs. Our findings identify Stat3 and NErbB-2 as novel therapeutic targets to inhibit ErbB-2-positive BC metastasis.

Heregulin Co-opts PR Transcriptional Action Via Stat3 Role As a Coregulator to Drive Cancer Growth

Accumulated findings have demonstrated the presence of bidirectional interactions between progesterone receptor (PR) and the ErbB family of receptor tyrosine kinases signaling pathways in breast cancer. We previously revealed signal transducer and activator of transcription 3 (Stat3) as a nodal convergence point between said signaling pathways proving that Stat3 is activated by one of the ErbBs' ligands, heregulin (HRG)β1 via ErbB2 and through the co-option of PR as a signaling molecule. Here, we found that HRGβ1 induced Stat3 recruitment to the promoters of the progestin-regulated cell cycle modulators Bcl-XL and p21(CIP1) and also stimulated Stat3 binding to the mouse mammary tumor virus promoter, which carries consensus progesterone response elements. Interestingly, HRGβ1-activated Stat3 displayed differential functions on PR activity depending on the promoter bound. Indeed, Stat3 was required for PR binding in bcl-X, p21(CIP1), and c-myc promoters while exerting a PR coactivator function on the mouse mammary tumor virus promoter. Stat3 also proved to be necessary for HRGβ1-induced in vivo tumor growth. Our results endow Stat3 a novel function as a coregulator of HRGβ1-activated PR to promote breast cancer growth. These findings underscore the importance of understanding the complex interactions between PR and other regulatory factors, such as Stat3, that contribute to determine the context-dependent transcriptional actions of PR.

Evaluation of Humoral Response and Protective Efficacy of an Inactivated Vaccine Against Peste des Petits Ruminants Virus in Goats

Four goats were inoculated with an inactivated peste des petits ruminants virus (PPRV) vaccine. Three unvaccinated goats were kept as controls. After 36 days, the four goats were revaccinated. The immune response was monitored by virus neutralization test showing that two doses of the vaccine were able to stimulate strong immune response in all the vaccinated animals. The vaccinated goat and the controls were challenged with virulent PPRV intranasally. After PPRV challenge, the three control goats showed fever, viremia and virus excretion through mucosal surfaces, whereas the vaccinated goats were fully protected against PPRV infection and replication.

Progesterone receptor activation downregulates GATA3 by transcriptional repression and increased protein turnover promoting breast tumor growth

Introduction

The transcription factor GATA3 is involved in mammary gland development and is crucial for the maintenance of the differentiated status of luminal epithelial cells. The role of GATA3 in breast cancer as a tumor suppressor has been established, although insights into the mechanism of GATA3 expression loss are still required.

Methods

Chromatin immunoprecipitation assays were conducted to study progestin modulation of recruitment of transcription factors to GATA3 promoter. We performed western blot and reverse RT-qPCR experiments to explore progestin regulation of GATA3 protein and mRNA expression respectively. Confocal microscopy and in vitro phosphorylation studies were conducted to examine progestin capacity to induce GATA3 serine phosphorylation in its 308 residue. GATA3 participation in progestin-induced breast cancer growth was addressed in in vitro proliferation and in vivo tumor growth experiments.

Results

In this study, we demonstrate that progestin-activated progesterone receptor (PR) reduces GATA3 expression through regulation at the transcriptional and post-translational levels in breast cancer cells. In the former mechanism, the histone methyltransferase enhancer of zeste homolog 2 is co-recruited with activated PR to a putative progesterone response element in the GATA3 proximal promoter, increasing H3K27me3 levels and inducing chromatin compaction, resulting in decreased GATA3 mRNA levels. This transcriptional regulation is coupled with increased GATA3 protein turnover through progestin-induced GATA3 phosphorylation at serine 308 followed by 26S proteasome-mediated degradation. Both molecular mechanisms converge to accomplish decreased GATA3 expression levels in breast cancer cells upon PR activation. In addition, we demonstrated that decreased GATA3 levels are required for progestin-induced upregulation of cyclin A2, which mediates the G1 to S phase transition of the cell cycle and was reported to be associated with poor prognosis in breast cancer. Finally, we showed that downregulation of GATA3 is required for progestin stimulation of both in vitro cell proliferation and in vivo tumor growth.

Conclusions

In the present study, we reveal that progestin-induced PR activation leads to loss of GATA3 expression in breast cancer cells through transcriptional and post-translational regulation. Importantly, we demonstrate that GATA3 downregulation is required for progestin-induced upregulation of cyclin A2 and for progestin-induced in vitro and in vivo breast cancer cell growth.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-014-0491-x) contains supplementary material, which is available to authorized users.