Serum biomarker signature is predictive of the risk of hepatocellular cancer in patients with cirrhosis

BACKGROUND

Inflammatory and metabolic biomarkers have been associated with hepatocellular cancer (HCC) risk in phases I and II biomarker studies. We developed and internally validated a robust metabolic biomarker panel predictive of HCC in a longitudinal phase III study.

METHODS

We used data and banked serum from a prospective cohort of 2266 adult patients with cirrhosis who were followed until the development of HCC (n=126). We custom designed a FirePlex immunoassay to measure baseline serum levels of 39 biomarkers and established a set of biomarkers with the highest discriminatory ability for HCC. We performed bootstrapping to evaluate the predictive performance using C-index and time-dependent area under the receiver operating characteristic curve (AUROC). We quantified the incremental predictive value of the biomarker panel when added to previously validated clinical models.

RESULTS

We identified a nine-biomarker panel (P9) with a C-index of 0.67 (95% CI 0.66 to 0.67), including insulin growth factor-1, interleukin-10, transforming growth factor β1, adipsin, fetuin-A, interleukin-1 β, macrophage stimulating protein α chain, serum amyloid A and TNF-α. Adding P9 to our clinical model with 10 factors including AFP improved AUROC at 1 and 2 years by 4.8% and 2.7%, respectively. Adding P9 to aMAP score improved AUROC at 1 and 2 years by 14.2% and 7.6%, respectively. Adding AFP L-3 or DCP did not change the predictive ability of the P9 model.

CONCLUSIONS

We identified a panel of nine serum biomarkers that is independently associated with developing HCC in cirrhosis and that improved the predictive ability of risk stratification models containing clinical factors.

Abstract 1705: SPOP: An essential gene for normal and prostate tumor cells

Background: Prostate cancer (PC) is the single most common and second-most lethal cancer in men, with over 268,000 estimated cases and over 34,500 estimated deaths in the US in 2022. The Speckle-Type POZ protein (SPOP) mutant subclass of PC accounts for 10% to 15% of all primary PC cases. SPOP is an adaptor for Cullin3/Ring (CUL3-RING)-type E3 ubiquitin ligase complexes and provides substrate specificity. The Cancer Genome Atlas (TCGA) studies show that SPOP is the most frequently mutated gene in primary prostate cancer (PC). Interestingly, PC-associated SPOP mutations are always missense and occur in a heterozygous fashion. The current gap in knowledge is the lack of understanding of the role of wildtype SPOP in PC.

Methods: By utilizing prostate specific SPOP knockout (KO) mice, we recently reported increased levels of AR and MYC protein and increased cellular turnover (both proliferation and apoptosis) in the prostate luminal epithelium compared to wildtype prostates. We now characterized these mice for the expression of Cre protein and SPOP mRNA at different age using immunohistochemistry and RNA in situ hybridization. Furthermore, we performed RNA-sequencing analysis in the SPOP knockout mice and matched control littermates. Moreover, we performed RNA-seq in LNCaP, LNCaP-Abl, and RWPE1 cells following SPOP inhibition via siRNA targeting SPOP. Finally, we compared our SPOP inhibition signature from in vitro cell lines and prostate specific SPOP knockout murine model to gain insights about the role of wildtype SPOP protein in the prostate epithelium.

Result: Using our Spopfl/fl;PBCre+ model, we observed SPOP floxed cells are rapidly lost and the murine prostate epithelium was repopulated with SPOP wildtype carrying cells. Similarly, knockdown (KD) of SPOP through siRNA treatment in a panel of PC cell lines resulted in a significant reduction in cell viability. These observations suggest that SPOP is important for the normal prostate cell viability. Further transcriptomic profiling of SPOP KO (from transgenic murine model) as well as siSPOP treated in vitro prostate cell lines revealed a significant reduction in the transcriptional activity of the AR.

Conclusion: Our data illustrate for the first time a critical role for SPOP in the growth and survival of the prostate epithelium and prostate cancer cell. Our findings further validates SPOP as a important therapeutic target for the treatment of prostate cancer.

Citation Format: Kinza Rizwan, Darlene Skapura, Cammy Mason, Cristian Coarfa, Nicholas Mitsiades, Damian Young, Salma Kaochar. SPOP: An essential gene for normal and prostate tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1705.

Abstract 442: Developing a lipogenesis inhibitor for prostate cancer

Background: Prostate cancer (PC) is the single most common and second most lethal cancer in men. Despite therapeutic advances in androgen receptor (AR)-targeting agents, progression to lethal, drug-resistant, castration-resistant prostate cancer (CRPC) remains a major clinical problem. Thus, there is an unmet need for novel treatment approaches and novel, druggable therapeutic targets in metastatic CRPC. Profiling of PC patient samples shows increases in two master regulators of lipogenesis-sterol regulatory binding proteins 1 and 2 (SREBP1 and SREBP2)-and their transcriptional targets. Overexpression of SREBP1 and SREBP2 and their target genes has been associated with tumor aggressiveness, poor clinical outcomes, and drug resistance in PC. The activation and nuclear translocation of SREBPs is tightly regulated by SREBP cleavage-activating protein (SCAP). We propose targeting SCAP will simultaneously block the activation and subsequent activity of all three SREBPs and that this represents a promising therapeutic strategy to treat CRPC.

Methods: To increase our understanding of SREBP biology in PC cells, we defined the cistrome of SREBPs across multiple PC cell lines via ChIP-Seq. We compared the transcriptomic profiles of genetic targeting of SREBP via siRNA and pharmacological targeting via the novel SCAP inhibitor, SCAPi. We evaluated the effect of SCAPi on cell viability, cell invasion, and AR-signaling in multiple PC cell lines using immunoblotting, luciferase reporters, flow cytometry, MTT, and invasion assays. Additionally, we will evaluate the anticancer activity and safety profile of our novel SCAPi using CDX mouse models.

Results: We found that inhibition of SCAP via siRNA and via SCAPi both yielded similar gene signatures, particularly the perturbation of cell cycle and lipogenesis genes. SCAPi dramatically reduces cell viability, migration, invasion, and expression of both AR- and SREBP-target genes in multiple PC cell lines. Through flow cytometry (Annexin V) and western blots (cleaved PARP) we found SCAPi induces apoptosis within 48 hours in PC cells. Pilot studies in tumor-bearing mice show SCAPi significantly increases survival without inducing animal weight loss.

Conclusions: There is a critical need for novel targets in PC, and dysregulated lipogenesis is an untargeted oncogenic pathway. Our work furthers the field’s understanding of hijacked lipogenesis in PC and paves the way for a first-in-class inhibitor of lipogenesis to treat lethal PC.

Citation Format: Dallin Lowder, Jin Na Shin, Maria E. Ruiz-Echartea, Darlene Skapura, Jenny Deng, Aleksandra Rusin, Christel Davis, Erik Ehli, Cristian Coarfa, Michael Ittmann, Salma Kaochar. Developing a lipogenesis inhibitor for prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 442.

Inhibition of GATA2 in prostate cancer by a clinically available small molecule

Castration-resistant prostate cancer (CRPC) remains highly lethal and in need of novel, actionable therapeutic targets. The pioneer factor GATA2 is a significant prostate cancer (PC) driver and is linked to poor prognosis. GATA2 directly promotes androgen receptor (AR) gene expression (both full-length and splice-variant) and facilitates AR binding to chromatin, recruitment of coregulators, and target gene transcription. Unfortunately, there is no clinically applicable GATA2 inhibitor available at the moment. Using a bioinformatics algorithm, we screened in silico 2650 clinically relevant drugs for a potential GATA2 inhibitor. Validation studies used cytotoxicity and proliferation assays, global gene expression analysis, RT-qPCR, reporter assay, reverse phase protein array analysis (RPPA), and immunoblotting. We examined target engagement via cellular thermal shift assay (CETSA), ChIP-qPCR, and GATA2 DNA-binding assay. We identified the vasodilator dilazep as a potential GATA2 inhibitor and confirmed on-target activity via CETSA. Dilazep exerted anticancer activity across a broad panel of GATA2-dependent PC cell lines in vitro and in a PDX model in vivo. Dilazep inhibited GATA2 recruitment to chromatin and suppressed the cell-cycle program, transcriptional programs driven by GATA2, AR, and c-MYC, and the expression of several oncogenic drivers, including AR, c-MYC, FOXM1, CENPF, EZH2, UBE2C, and RRM2, as well as of several mediators of metastasis, DNA damage repair, and stemness. In conclusion, we provide, via an extensive compendium of methodologies, proof-of-principle that a small molecule can inhibit GATA2 function and suppress its downstream AR, c-MYC, and other PC-driving effectors. We propose GATA2 as a therapeutic target in CRPC.

Abstract IA15: Development of Novel Models and Identification of Therapeutic Vulnerabilities in Highly Aggressive Prostate Cancer In African American Men

African Americans have the highest mortality rate and shortest survival of any racial/ethnic group in the US for most cancers. An estimated 29,570 cases of prostate cancer are expected to be diagnosed in AA men in 2020. The average annual incidence rate for African American men is 76% higher than the rate in Caucasian Americans. Prostate cancer is the second leading cause of cancer death in African American men, with an estimated 5,350 deaths expected in 2020, which is the highest of all ethnic groups (2.2X higher than Caucasian men). These disparities are appalling and demand immediate action. While the underlying causes are multifactorial, recent studies demonstrate that African American men are at higher risk of being diagnosed with prostate cancer, have higher Gleason grades, and increased risk of progression after radical prostatectomy (RP), even in equal access settings and after accounting for socioeconomic status. These data strongly argue that there is a significant underlying biological/genetic difference between African Americans and Caucasian American men with prostate cancer. Importantly, they highlight an unmet need in order to deliver personalized therapeutic options and ultimately, improve clinical outcomes. Unfortunately, most preclinical studies are performed in prostate cancer cell lines and patient-derived xenografts (PDXs) isolated from patients of Caucasian origin. At Baylor College of Medicine, we are leveraging the high numbers of minority cancer patients in our GU clinics, to generate and utilize innovative prostate cancer PDX and organoid models of diverse racial/ethnic minority origin, which will broaden our understanding of the molecular basis of the disease as well as expedite the drug discovery process. We will discuss preliminary findings from our ongoing studies in genomic and transcriptomic profiling of African American patients, progress in our development of novel prostate cancer models, and lastly, emerging therapeutic opportunities based on precision oncology.

Citation Format: Salma Kaochar, Patricia Castro, Sandra Grimm, Darlene Skapura, Matthew Rodriguez, Maurice Dufilho, Cammy Mason, Maria Machado Heredia, Quentxia Wrighting, Jami Daly, Matthew Robertson, Nora Navone, Jacob Berchuck, Matthew Freeman, Zoltan Szallasi, Albert Dobi, Guiherme Godoy, Michael Scheurer, Heidi Dowst, Susan Hilsenbeck, Martha Mims, Anita Sabichi, Edward Yen, Cristian Coarfa, Michael Ittmann, Nicholas Mitsiades. Development of Novel Models and Identification of Therapeutic Vulnerabilities in Highly Aggressive Prostate Cancer In African American Men [abstract]. In: Proceedings of the AACR Virtual Conference: Thirteenth AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2020 Oct 2-4. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(12 Suppl):Abstract nr IA15.

Novel junctophilin-2 mutation A405S is associated with basal septal hypertrophy and diastolic dysfunction

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A JPH2 A405S mutation was found in a human HCM patient.

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A novel echocardiographic imaging plane revealed septal hypertrophy in a mouse model bearing the human JPH2 mutation, thereby causally linking it to HCM pathogenesis.

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This alpha helical JPH2 mutation resulted in decreased transverse tubule regularity and aberrant calcium handling in septal cardiomyocytes.

Junctophilin-2 (JPH2) is a structural calcium (Ca²⁺) handling protein, which approximates the cardiomyocyte transverse tubules (TTs) to the sarcoplasmic reticulum. This facilitates communication of the voltage-gated Ca²⁺ channel and the ryanodine receptor RyR2. A human patient with hypertrophic cardiomyopathy was positive for a JPH2 mutation substituting alanine-405—located within the alpha helix domain—with a serine (A405S). Using a novel mouse echocardiography plane, we found that mice bearing this JPH2 mutation developed increased subvalvular septal thickness. Cardiomyocytes from the septa of these mice displayed irregular TTs and abnormal Ca²⁺ handling including increased SERCA activity.

Phospholamban ablation rescues the enhanced propensity to arrhythmias of mice with CaMKII-constitutive phosphorylation of RyR2 at site S2814

KEY POINTS

Mice with Ca(2+) -calmodulin-dependent protein kinase (CaMKII) constitutive pseudo-phosphorylation of the ryanodine receptor RyR2 at Ser2814 (S2814D(+/+) mice) exhibit a higher open probability of RyR2, higher sarcoplasmic reticulum (SR) Ca(2+) leak in diastole and increased propensity to arrhythmias under stress conditions. We generated phospholamban (PLN)-deficient S2814D(+/+) knock-in mice by crossing two colonies, S2814D(+/+) and PLNKO mice, to test the hypothesis that PLN ablation can prevent the propensity to arrhythmias of S2814D(+/+) mice. PLN ablation partially rescues the altered intracellular Ca(2+) dynamics of S2814D(+/+) hearts and myocytes, but enhances SR Ca(2+) sparks and leak on confocal microscopy. PLN ablation diminishes ventricular arrhythmias promoted by CaMKII phosphorylation of S2814 on RyR2. PLN ablation aborts the arrhythmogenic SR Ca(2+) waves of S2814D(+/+) and transforms them into non-propagating events. A mathematical human myocyte model replicates these results and predicts the increase in SR Ca(2+) uptake required to prevent the arrhythmias induced by a CaMKII-dependent leaky RyR2.

ABSTRACT

Mice with constitutive pseudo-phosphorylation at Ser2814-RyR2 (S2814D(+/+) ) have increased propensity to arrhythmias under β-adrenergic stress conditions. Although abnormal Ca(2+) release from the sarcoplasmic reticulum (SR) has been linked to arrhythmogenesis, the role played by SR Ca(2+) uptake remains controversial. We tested the hypothesis that an increase in SR Ca(2+) uptake is able to rescue the increased arrhythmia propensity of S2814D(+/+) mice. We generated phospholamban (PLN)-deficient/S2814D(+/+) knock-in mice by crossing two colonies, S2814D(+/+) and PLNKO mice (SD(+/+) /KO). SD(+/+) /KO myocytes exhibited both increased SR Ca(2+) uptake seen in PLN knock-out (PLNKO) myocytes and diminished SR Ca(2+) load (relative to PLNKO), a characteristic of S2814D(+/+) myocytes. Ventricular arrhythmias evoked by catecholaminergic challenge (caffeine/adrenaline) in S2814D(+/+) mice in vivo or programmed electric stimulation and high extracellular Ca(2+) in S2814D(+) /(-) hearts ex vivo were significantly diminished by PLN ablation. At the myocyte level, PLN ablation converted the arrhythmogenic Ca(2+) waves evoked by high extracellular Ca(2+) provocation in S2814D(+/+) mice into non-propagated Ca(2+) mini-waves on confocal microscopy. Myocyte Ca(2+) waves, typical of S2814D(+/+) mice, could be evoked in SD(+/+) /KO cells by partially inhibiting SERCA2a. A mathematical human myocyte model replicated these results and allowed for predicting the increase in SR Ca(2+) uptake required to prevent the arrhythmias induced by a Ca(2+) -calmodulin-dependent protein kinase (CaMKII)-dependent leaky RyR2. Our results demonstrate that increasing SR Ca(2+) uptake by PLN ablation can prevent the arrhythmic events triggered by SR Ca(2+) leak due to CaMKII-dependent phosphorylation of the RyR2-S2814 site and underscore the benefits of increasing SERCA2a activity on SR Ca(2+) -triggered arrhythmias.

Impaired local regulation of ryanodine receptor type 2 by protein phosphatase 1 promotes atrial fibrillation

AIMS

Altered Ca(2+) handling in atrial fibrillation (AF) has been associated with dysregulated protein phosphatase 1 (PP1) and subcellular heterogeneities in protein phosphorylation, but the underlying mechanisms remain unclear. This is due to a lack of investigation into the local, rather than global, regulation of PP1 on different subcellular targets such as ryanodine receptor type 2 (RyR2), especially in AF.

METHODS AND RESULTS

We tested the hypothesis that impaired local regulation of PP1 causes RyR2 hyperphosphorylation thereby promoting AF susceptibility. To specifically disrupt PP1's local regulation of RyR2, we used the spinophilin knockout (Sp(-/-)) mice (Mus musculus) since PP1 is targeted to RyR2 via spinophilin. Without spinophilin, the interaction between PP1 and RyR2 was reduced by 64%, while RyR2 phosphorylation was increased by 43% at serine (S)2814 but unchanged at S2808. Lipid bilayer experiments revealed that single RyR2 channels isolated from Sp(-/-) hearts had an increased open probability. Likewise, Ca(2+) spark frequency normalized to sarcoplasmic reticulum Ca(2+) content was also enhanced in Sp(-/-) atrial myocytes, but normalized by Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) inhibitors KN-93 and AIP and also by genetic inhibition of RyR2 S2814 phosphorylation. Finally, Sp(-/-) mice exhibited increased atrial ectopy and susceptibility to pacing-induced AF, both of which were also prevented by the RyR2 S2814A mutation.

CONCLUSION

PP1 regulates RyR2 locally by counteracting CaMKII phosphorylation of RyR2. Decreased local PP1 regulation of RyR2 contributes to RyR2 hyperactivity and promotes AF susceptibility. This represents a novel mechanism for subcellular modulation of calcium channels and may represent a potential drug target of AF.

Intracellular calcium leak due to FKBP12.6 deficiency in mice facilitates the inducibility of atrial fibrillation

BACKGROUND

Although defective Ca(2+) homeostasis may contribute to arrhythmogenesis in atrial fibrillation (AF), the underlying molecular mechanisms remain poorly understood. Studies in patients with AF revealed that impaired diastolic closure of sarcoplasmic reticulum (SR) Ca(2+)-release channels (ryanodine receptors, RyR2) is associated with reduced levels of the RyR2-inhibitory subunit FKBP12.6.

OBJECTIVE

The objective of the present study was to test the hypothesis that Ca(2+) leak from the SR through RyR2 increases the propensity for AF in FKBP12.6-deficient (-/-) mice.

METHODS

Surface electrocardiogram and intracardiac electrograms were recorded simultaneously in FKBP12.6-/- mice and wild-type (WT) littermates. Right atrial programmed stimulation was performed before and after injection of RyR2 antagonist tetracaine (0.5 mg/kg). Intracellular Ca(2+) transients were recorded in atrial myocytes from FKBP12.6-/- and WT mice.

RESULTS

FKBP12.6-/- mice had structurally normal atria and unaltered expression of key Ca(2+)-handling proteins. AF episodes were inducible in 81% of FKBP12.6-/-, but in only 7% of WT mice (P <.05), and were prevented by tetracaine in all FKBP12.6-/- mice. SR Ca(2+) leak in FKBP12.6-/- myocytes was 53% larger than in WT myocytes, and FKBP12.6-/- myocytes showed increased incidence of spontaneous SR Ca(2+) release events, which could be blocked by tetracaine.

CONCLUSION

The increased vulnerability to AF in FKBP12.6-/- mice substantiates the notion that defective SR Ca(2+) release caused by abnormal RyR2 and FKBP12.6 interactions may contribute to the initiation or maintenance of atrial fibrillation.

Retroviral insertions in the VISION database identify molecular pathways in mouse lymphoid leukemia and lymphoma

AKXD recombinant inbred (RI) strains develop a variety of leukemias and lymphomas due to somatically acquired insertions of retroviral DNA into the genome of hematopoetic cells that can mutate cellular proto-oncogenes and tumor suppressor genes. We generated a new set of tumors from nine AKXD RI strains selected for their propensity to develop B-cell tumors, the most common type of human hematopoietic cancers. We employed a PCR technique called viral insertion site amplification (VISA) to rapidly isolate genomic sequence at the site of provirus insertion. Here we describe 550 VISA sequence tags (VSTs) that identify 74 common insertion sites (CISs), of which 21 have not been identified previously. Several suspected proto-oncogenes and tumor suppressor genes lie near CISs, providing supportive evidence for their roles in cancer. Furthermore, numerous previously uncharacterized genes lie near CISs, providing a pool of candidate disease genes for future research. Pathway analysis of candidate genes identified several signaling pathways as common and powerful routes to blood cancer, including Notch, E-protein, NFκB, and Ras signaling. Misregulation of several Notch signaling genes was confirmed by quantitative RT-PCR. Our data suggest that analyses of insertional mutagenesis on a single genetic background are biased toward the identification of cooperating mutations. This tumor collection represents the most comprehensive study of the genetics of B-cell leukemia and lymphoma development in mice. We have deposited the VST sequences, CISs in a genome viewer, histopathology, and molecular tumor typing data in a public web database called VISION (Viral Insertion Sites Identifying Oncogenes), which is located at http://www.mouse-genome.bcm.tmc.edu/vision.

Genetic profile of insertion mutations in mouse leukemias and lymphomas

Murine leukemia retroviruses (MuLVs) cause leukemia and lymphoma in susceptible strains of mice as a result of insertional mutation of cellular proto-oncogenes or tumor suppressor genes. Using a novel approach to amplify and sequence viral insertion sites, we have sequenced >200 viral insertion sites from which we identify >35 genes altered by viral insertion in four AKXD mouse strains. The class of genes most frequently altered are transcription factors, however, insertions are found near genes involved in signal transduction, cell cycle control, DNA repair, cell division, hematopoietic differentiation, and near many ESTs and novel loci. Many of these mutations identify genes that have not been implicated in cancer. By isolating nearly all the somatic viral insertion mutations contributing to disease in these strains we show that each AKXD strain displays a unique mutation profile, suggesting strain-specific susceptibility to mutations in particular genetic pathways.