TFEB and TFE3 drive kidney cystogenesis and tumorigenesis

Birt-Hogg-Dubé (BHD) syndrome is an inherited familial cancer syndrome characterized by the development of cutaneous lesions, pulmonary cysts, renal tumors and cysts and caused by loss-of-function pathogenic variants in the gene encoding the tumor-suppressor protein folliculin (FLCN). FLCN acts as a negative regulator of TFEB and TFE3 transcription factors, master controllers of lysosomal biogenesis and autophagy, by enabling their phosphorylation by the mechanistic Target Of Rapamycin Complex 1 (mTORC1). We have previously shown that deletion of Tfeb rescued the renal cystic phenotype of kidney-specific Flcn KO mice. Using Flcn/Tfeb/Tfe3 double and triple KO mice, we now show that both Tfeb and Tfe3 contribute, in a differential and cooperative manner, to kidney cystogenesis. Remarkably, the analysis of BHD patient-derived tumor samples revealed increased activation of TFEB/TFE3-mediated transcriptional program and silencing either of the two genes rescued tumorigenesis in human BHD renal tumor cell line-derived xenografts (CDXs). Our findings demonstrate in disease-relevant models that both TFEB and TFE3 are key drivers of renal tumorigenesis and suggest novel therapeutic strategies based on the inhibition of these transcription factors.

Abstract A15: New treatment opportunities by in vivo and in vitro screening approaches in melanoma

Treatment of metastatic melanoma has been recently revolutionized by the use of targeted and immune inhibitors, though efficiently working only in a fraction of patients. Adverse effects still represent major challenges, as well as the rapid development of drug resistance upon treatment, thus suggesting that it is of utmost importance to elucidate additional molecular pathways and targets to better understand the biology of this tumor. In vivo RNAi screens done in patient-derived xenografts (PDXs) that fully phenocopy the original tumor of the patient represent a powerful tool to identify new putative essential and druggable candidates, and to repurpose drugs already approved for other indications. To this end we have recently generated a platform of melanoma PDXs with which we can recapitulate both melanoma growth and metastasization. We have performed in vivo shRNA screens, where we have found numerous and patient-specific epigenetic genes essential for tumor growth in vivo. With this platform, we have isolated novel frailties whose depletion favors cell senescence. Preliminary data using shRNA libraries of actionable genes for which drugs are already available suggest that specific drugs can be repurposed for melanoma treatment. We have proved that this approach can work in vivo, and we propose to convert it in an in vitro assay to rapidly translate new discoveries to the patient.

Note: This abstract was not presented at the conference.

Citation Format: Federica Marocchi, Letizia Granieri, Fiorenza Lotti, Fernando Palluzzi, Jole Costanza, Laura Riva, Daniela Bossi, Luisa Lanfrancone. New treatment opportunities by in vivo and in vitro screening approaches in melanoma [abstract]. In: Proceedings of the AACR Special Conference on Melanoma: From Biology to Target; 2019 Jan 15-18; Houston, TX. Philadelphia (PA): AACR; Cancer Res 2020;80(19 Suppl):Abstract nr A15.

Identification of CDC25 as a Common Therapeutic Target for Triple-Negative Breast Cancer

CDK4/6 inhibitors are effective against cancer cells expressing the tumor suppressor RB1, but not RB1-deficient cells, posing the challenge of how to target RB1 loss. In triple-negative breast cancer (TNBC), RB1 and PTEN are frequently inactivated together with TP53. We performed kinome/phosphatase inhibitor screens on primary mouse Rb/p53-, Pten/p53-, and human RB1/PTEN/TP53-deficient TNBC cell lines and identified CDC25 phosphatase as a common target. Pharmacological or genetic inhibition of CDC25 suppressed growth of RB1-deficient TNBC cells that are resistant to combined CDK4/6 plus CDK2 inhibition. Minimal cooperation was observed in vitro between CDC25 antagonists and CDK1, CDK2, or CDK4/6 inhibitors, but strong synergy with WEE1 inhibition was apparent. In accordance with increased PI3K signaling following long-term CDC25 inhibition, CDC25 and PI3K inhibitors effectively synergized to suppress TNBC growth both in vitro and in xenotransplantation models. These results provide a rationale for the development of CDC25-based therapies for diverse RB1/PTEN/TP53-deficient and -proficient TNBCs.

Liu et al. report that inhibition of the protein phosphatase CDC25 kills diverse triple-negative breast cancer (TNBC) cells. Moreover, CDC25 antagonists cooperate with other drugs, such as PI3K inhibitors, to efficiently suppress growth of human TNBC engrafted into mice.

A Na+ /Ca2+ exchanger of the olive pathogen Pseudomonas savastanoi pv. savastanoi is critical for its virulence

In a number of compatible plant-bacterium interactions, a rise in apoplastic Ca2+ levels is observed, suggesting that Ca2+ represents an important environmental clue, as reported for bacteria infecting mammalians. We demonstrate that Ca2+ entry in Pseudomonas savastanoi pv. savastanoi (Psav) strain DAPP-PG 722 is mediated by a Na+ /Ca2+ exchanger critical for virulence. Using the fluorescent Ca2+ probe Fura 2-AM, we demonstrate that Ca2+ enters Psav cells foremost when they experience low levels of energy, a situation mimicking the apoplastic fluid. In fact, Ca2+ entry was suppressed in the presence of high concentrations of glucose, fructose, sucrose or adenosine triphosphate (ATP). Since Ca2+ entry was inhibited by nifedipine and LiCl, we conclude that the channel for Ca2+ entry is a Na+ /Ca2+ exchanger. In silico analysis of the Psav DAPP-PG 722 genome revealed the presence of a single gene coding for a Na+ /Ca2+ exchanger (cneA), which is a widely conserved and ancestral gene within the P. syringae complex based on gene phylogeny. Mutation of cneA compromised not only Ca2+ entry, but also compromised the Hypersensitive response (HR) in tobacco leaves and blocked the ability to induce knots in olive stems. The expression of both pathogenicity (hrpL, hrpA and iaaM) and virulence (ptz) genes was reduced in this Psav-cneA mutant. Complementation of the Psav-cneA mutation restored both Ca2+ entry and pathogenicity in olive plants, but failed to restore the HR in tobacco leaves. In conclusion, Ca2+ entry acts as a 'host signal' that allows and promotes Psav pathogenicity on olive plants.

CDC25 as a common therapeutic target for triple-negative breast cancer - the challenges ahead

The dual phosphatase CDC25 has recently been identified as a target for diverse triple-negative breast cancers including RB1/PTEN/P53-deficient tumors. Moreover, CDC25 inhibitors effectively synergize with PI3K inhibitors to suppress tumor growth. We discuss these findings and the challenges that lie ahead in bringing CDC25 inhibitors to the clinic.

High-throughput drug library screening identifies colchicine as a thyroid cancer inhibitor

We employed a high-throughput drug library screening platform to identify novel agents affecting thyroid cancer cells. We used human thyroid cancer cell lines to screen a collection of approximately 5200 small molecules with biological and/or pharmacologial properties. Parallel primary screens yielded a number of hits differentially active between thyroid and melanoma cells. Amongst compounds specifically targeting thyroid cancer cells, colchicine emerged as an effective candidate. Colchicine inhibited cell growth which correlated with G2 cell cycle arrest and apoptosis. These effects were hampered through inhibition of MEK1/2 and JNK. In contrast, inhibition of p38-MAPK had little effect, and AKT had no impact on colchicine action. Systemic colchicine inhibited thyroid cancer progression in xenografted mice. These findings demonstrate that our screening platform is an effective vehicle for drug reposition and show that colchicine warrants further attention in well-defined clinical niches such as thyroid cancer.

Aquaporin-4 antibody titration in NMO patients treated with rituximab: A retrospective study

Objective:

We undertook an observational retrospective study to investigate the usefulness of aquaporin-4 (AQP4) antibodies (Ab) titration in the management of patients with neuromyelitis optica (NMO) treated with rituximab (RTX) by studying (1) the correlation between AQP4-Ab titer and disease activity, (2) the influence of RTX on antibody levels, and (3) the association between AQP4-Ab levels and responsiveness to RTX.

Methods:

A cell-based assay was used for AQP4-Ab titration in 322 serum samples from 7 patients with NMO treated with RTX (median follow-up 65 months), according to a treatment-to-target approach. Serum samples were collected every month following standardized procedures.

Results:

(1) In group analysis, AQP4-Ab titers correlated with the disease activity, showing higher titers during and preceding relapses than during remission. However, in individual analysis, an increase in AQP4-Ab titers and CD19+ B cells did not always precede a relapse. (2) A reduction of AQP4-Ab titers in the short-term and long-term period was observed during RTX treatment. (3) Reduction of AQP4-Ab titers was observed in responder patients both 3 months after RTX infusion and in the long-term follow-up. In one nonresponder patient, AQP4-Ab levels never decreased during the treatment period.

Conclusions:

Titration of AQP4-Abs could be useful in the clinical management of patients with NMO treated with RTX: titration before each reinfusion and 3 months after each reinfusion may provide information about responsiveness to RTX. Although a relationship among AQP4-Ab levels, disease activity, and response to RTX was observed, the usefulness of AQP4-Ab titration to predict relapses is limited.

Multicentre comparison of a diagnostic assay: aquaporin-4 antibodies in neuromyelitis optica

OBJECTIVE

Antibodies to cell surface central nervous system proteins help to diagnose conditions which often respond to immunotherapies. The assessment of antibody assays needs to reflect their clinical utility. We report the results of a multicentre study of aquaporin (AQP) 4 antibody (AQP4-Ab) assays in neuromyelitis optica spectrum disorders (NMOSD).

METHODS

Coded samples from patients with neuromyelitis optica (NMO) or NMOSD (101) and controls (92) were tested at 15 European diagnostic centres using 21 assays including live (n=3) or fixed cell-based assays (n=10), flow cytometry (n=4), immunohistochemistry (n=3) and ELISA (n=1).

RESULTS

Results of tests on 92 controls identified 12assays as highly specific (0-1 false-positive results). 32 samples from 50 (64%) NMO sera and 34 from 51 (67%) NMOSD sera were positive on at least two of the 12 highly specific assays, leaving 35 patients with seronegative NMO/spectrum disorder (SD). On the basis of a combination of clinical phenotype and the highly specific assays, 66 AQP4-Ab seropositive samples were used to establish the sensitivities (51.5-100%) of all 21 assays. The specificities (85.8-100%) were based on 92 control samples and 35 seronegative NMO/SD patient samples.

CONCLUSIONS

The cell-based assays were most sensitive and specific overall, but immunohistochemistry or flow cytometry could be equally accurate in specialist centres. Since patients with AQP4-Ab negative NMO/SD require different management, the use of both appropriate control samples and defined seronegative NMOSD samples is essential to evaluate these assays in a clinically meaningful way. The process described here can be applied to the evaluation of other antibody assays in the newly evolving field of autoimmune neurology.

Antagonistic Effect of a Salivary Proline-Rich Peptide on the Cytosolic Ca2+ Mobilization Induced by Progesterone in Oral Squamous Cancer Cells

A salivary proline-rich peptide of 1932 Da showed a dose-dependent antagonistic effect on the cytosolic Ca²⁺ mobilization induced by progesterone in a tongue squamous carcinoma cell line. Structure-activity studies showed that the activity of the peptide resides in the C-terminal region characterized by a proline stretch flanked by basic residues. Furthermore, lack of activity of the retro-inverso peptide analogue suggested the involvement of stereospecific recognition. Mass spectrometry-based shotgun analysis, combined with Western blotting tests and biochemical data obtained with the Progesterone Receptor Membrane Component 1 (PGRMC1) inhibitor AG205, showed strong evidence that p1932 performs its modulatory action through an interaction with the progesterone receptor PGRMC1, which is predominantly expressed in this cell line and, clearly, plays a role in progesterone induced Ca²⁺ response. Thus, our results point to p1932 as a modulator of the transduction signal pathway mediated by this protein and, given a well-established involvement of PGRMC1 in tumorigenesis, highlight a possible therapeutic potential of p1932 for the treatment of oral cancer.

Immune and Epstein-Barr virus gene expression in cerebrospinal fluid and peripheral blood mononuclear cells from patients with relapsing-remitting multiple sclerosis

Background

Gene expression analyses in paired cerebrospinal fluid (CSF) and peripheral blood mononuclear cells (PBMC) from patients with multiple sclerosis (MS) are restrained by the low RNA amounts from CSF cells and low expression levels of certain genes. Here, we applied a Taqman-based pre-amplification real-time reverse-transcription polymerase chain reaction (RT-PCR) (PreAmp RT-PCR) to cDNA from CSF cells and PBMC of MS patients and analyzed multiple genes related to immune system function and genes expressed by Epstein-Barr virus (EBV), a herpesvirus showing strong association with MS. Using this enhanced RT-PCR method, we aimed at the following: (1) identifying gene signatures potentially useful for patient stratification, (2) understanding whether EBV infection is perturbed in CSF and/or blood, and (3) finding a link between immune and EBV infection status.

Methods

Thirty-one therapy-free patients with relapsing-remitting MS were included in the study. Paired CSF cells and PBMC were collected and expression of 41 immune-related cellular genes and 7 EBV genes associated with latent or lytic viral infection were determined by PreAmp RT-PCR. Clinical, radiological, CSF, and gene expression data were analyzed using univariate and multivariate (cluster analysis, factor analysis) statistical approaches.

Results

Several immune-related genes were differentially expressed between CSF cells and PBMC from the whole MS cohort. By univariate analysis, no or only minor differences in gene expression were found associated with sex, clinical, or radiological condition. Cluster analysis on CSF gene expression data grouped patients into three clusters; clusters 1 and 2 differed by expression of genes that are related mainly to innate immunity, irrespective of sex and disease characteristics. By factor analysis, two factors grouping genes involved in antiviral immunity and immune regulation, respectively, accurately discriminated cluster 1 and cluster 2 patients. Despite the use of an enhanced RT-PCR method, EBV transcripts were detected in a minority of patients (5 of 31), with evidence of viral latency activation in CSF cells or PBMC and of lytic infection in one patient with active disease only.

Conclusions

Analysis of multiple cellular and EBV genes in paired CSF cell and PBMC samples using PreAmp RT-PCR may yield new information on the complex interplay between biological processes underlying MS and help in biomarker identification.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-015-0353-1) contains supplementary material, which is available to authorized users.

CD19 mRNA quantification improves rituximab treatment-to-target approach: a proof of concept study

We compared pre-amplification (PA) RT-PCR blood CD19 mRNA quantification with flow cytometry (FC), to personalize rituximab re-treatment in neuromyelitis optica spectrum disorders (NMOSDs) patients. 47 blood samples from 3 NMOSDs patients were studied. PA-RT-PCR quantified CD19 in all samples, and a positivity threshold was defined, whereas CD19+ B cells were under threshold in 31/47 samples by FC. In all samples where CD19+ B cells were above FC threshold, they resulted above the PA-RT-PCR threshold. CD19 mRNA was above threshold in 8 other samples, resulted negative by FC, and preceded the FC positivity in 7/8 samples by 1-3 months, showing major sensitivity.

Evaluation of a multiparametric immunofluorescence assay for standardization of neuromyelitis optica serology

BACKGROUND

Neuromyelitis optica (NMO) is a severely disabling autoimmune disorder of the central nervous system, which predominantly affects the optic nerves and spinal cord. In a majority of cases, NMO is associated with antibodies to aquaporin-4 (AQP4) (termed NMO-IgG).

AIMS

In this study, we evaluated a new multiparametric indirect immunofluorescence (IIF) assay for NMO serology.

METHODS

Sera from 20 patients with NMO, 41 patients with multiple sclerosis (MS), 30 healthy subjects, and a commercial anti-AQP4 IgG antibody were tested in a commercial composite immunofluorescence assay ("Neurology Mosaic 17"; Euroimmun, Germany), consisting of five different diagnostic substrates (HEK cells transfected with AQP4, non-transfected HEK cells, primate cerebellum, cerebrum, and optic nerve tissue sections).

RESULTS

We identified AQP4 specific and non-specific fluorescence staining patterns and established positivity criteria. Based on these criteria, this kit yielded a high sensitivity (95%) and specificity (100%) for NMO and had a significant positive and negative likelihood ratio (LR+ = ∞, LR- = 0.05). Moreover, a 100% inter- and intra-laboratory reproducibility was found.

CONCLUSIONS

The biochip mosaic assay tested in this study is a powerful tool for NMO serology, fast to perform, highly sensitive and specific for NMO, reproducible, and suitable for inter-laboratory standardization as required for multi-centre clinical trials.

Classification of individuals based on ex-vivo glatiramer acetate-induced interferon-γ and interleukin-4 response

Background: Glatiramer acetate (GA) in multiple sclerosis acts through the induction of GA-specific T-helper 2 cells. Nevertheless, the phenomenon is not universal in patients, explaining individual differences in clinical response.

Objective: The objective of this article was to categorize GA-treated patients.

Method: An enhanced quantitative PCR assay was used for measuring ex-vivo GA-induced IFNγ and IL4 mRNA responses in mononuclear cells from 23 healthy donors, 27 untreated patients, 33 short-term (≤6 months) and 77 long-term (>6 months) GA-treated patients. Thresholds for IFNγ and IL4 transcriptional response were calculated by ROC analysis and long-term treated patients were compared in terms of prognostic stratification.

Results: Thresholds for IFNγ and IL4 transcriptional response were calculated at 5.36 and 1.41 relative expression (RE). Finally, 67% of long-term treated patients scored above both response thresholds. These patients had a higher proportion of relapse-free subjects (74% vs 40% when compare to patients who scored below both thresholds) and a significantly better relapse-free survival rate ( p=0.006; CI 0.29–0.75). The negative predictive value to predict adverse clinical outcome was 79% (CI 0.63–0.90), meaning that by a positive response, there is a 79% chance that the patient will not experience a negative outcome at 3 years.

Conclusions: Our enhanced quantitative PCR assay produced clinically significant results for GA-treated patients. As such, if patients have a positive response, it means they have less chance of a relapse, while patients with a negative response have a greater probability of a worse outcome.

Anti-interferon-beta neutralising activity is not entirely mediated by antibodies

Many multiple sclerosis (MS) patients treated with interferon-beta (IFNbeta) develop anti-IFNbeta antibodies (BAbs), which can interfere with both in vitro and in vivo bioactivity of the injected cytokine. Objective of this study was to correlate these measures. Among the 256 enrolled patients, 11 (4.3%) showed a significant inhibition of the IFNbeta activity in vitro, but no measurable BAbs. As a whole, in vivo bioactivity was inhibited in 9/11 (82%) of these patients. A minority of IFNbeta treated patients have a non-antibody mediated neutralising activity, which competitively inhibits the bioactivity both in vitro and in vivo.

Probiotics, Prebiotics and Child Health: Where are We Going?

Changes in gastrointestinal (GI) bacteria caused by diet, antibiotics or other factors could alter enteric and systemic immune functions; changing the gut microflora composition by diet supplementation with specific live microbiota (probiotics) may be beneficial. The ‘natural’ target of ingested probiotics is the intestine, its microflora and associated immune system. Most published data concern use of probiotics to prevent and treat GI infections. Evidence for possible beneficial effects on mucosal barrier dysfunctions, including food allergy, inflammatory bowel disease, and respiratory and urinary tract infections, is emerging. The role of prebiotics (non-digestible oligosaccharides that reduce the growth or virulence of pathogens and induce systemic effects) is being investigated. Preliminary studies indicate that prebiotics may be useful dietary adjuncts for managing GI infections. Prebiotic and probiotic use in infants is attempting to modify a complex microbial ecosystem. Better understanding of the long-term effects of these interventions on infant gut microflora is an important goal.

Soy-based formulas and phyto-oestrogens: a safety profile

Phyto-oestrogens are non-steroidal plant-derived compounds that possess oestrogenic activity and act as selective oestrogen receptor modulators (SERMs). Among the dietary oestrogens, the isoflavone class enjoy a wide-spread distribution in most of the members of the Leguminosae family, including such prominent high-content representatives as soybean. Phyto-oestrogen research has grown rapidly in recent years owing to epidemiological studies suggesting that diets rich in soy may be associated with potential health benefits. There is a paucity of data on endocrine effects of soy phytochemicals during infancy, the most sensitive period of life for the induction of toxicity. The safety of isoflavones in infant formulas has been questioned recently owing to reports of possible hormonal effects. Infants fed soy formula receive high levels of phyto-oestrogens in the form of isoflavones (genistein, daidzein and their glycosides). To date, no adverse effects of short- or long-term use of soy proteins have been observed in humans and exposure to soy-based infant formulas does not appear to lead to different reproductive outcomes than exposure to cow milk formulas. Soy formula seems to be a safe feeding option for most infants. Nevertheless, much closer studies in experimental animals and human populations exposed to phyto-oestrogen-containing products, and particularly soy-based infant formulas, are necessary.