Harnessing Preclinical Molecular Imaging to Inform Advances in Personalized Cancer Medicine

Identification and Experimental Validation of Prognostic miRNA Signature and Ferroptosis-Related Key Genes in Cervical Squamous Cell Carcinoma

OBJECTIVES

This study aimed to investigate the prognostic value of miRNAs and ferroptosis-related genes in cervical squamous cell carcinoma.

METHODS

We mined data from public databases for differentially expressed miRNAs, ferroptosis-related genes, and clinical parameters and constructed a prognostic risk model. The predictive performance of the model was evaluated using survival and receiver operating characteristic curve analyses. We combined the clinicopathological features to construct a nomogram and evaluated its efficacy using calibration and clinical decision curves. The correlation between miRNA characteristics, risk score, and the tumor microenvironment was also studied. Next, consensus and key genes were screened, and their biological functions were analyzed using KEGG, GO, GSEA, and drug sensitivity analysis. Finally, the expression of miRNAs and key genes was detected using qRT-PCR and western blotting to verify the prediction results.

RESULTS

Seven miRNA signatures (miR-100-3p, miR-301a-5p, miR-331-3p, miR-425-5p, miR-502-3p, miR-505-5p, and miR-629-3p) were generated, and prognostic risk and nomogram models were successfully constructed. These models exhibited good accuracy. miRNA signatures correlated with the tumor microenvironment. Twelve consensus genes and three key genes (SLC2A1, ANO6, and TXNIP) were screened and their biofunctional diversity was identified using various analytical methods. qRT-PCR and western blotting were used to verify the expression of miR-301a-5p, miR-505-5p, SLC2A1, and TXNIP in cervical squamous carcinoma. The results were consistent with those of bioinformatics analyses.

CONCLUSIONS

Seven miRNAs may serve as prognostic biomarkers of cervical squamous cell carcinoma. SLC2A1, ANO6, and TXNIP are associated with cervical squamous cell carcinoma and may serve as ferroptosis-related markers of the disease.

miRNA-199a-5p/SLC2A1 axis regulates glucose metabolism in non-small cell lung cancer

Lung cancer is acknowledged as a common cancer with high morbidity and mortality. MicroRNAs (miRNAs), kind of non-coding single-stranded RNA molecules, can be used in cancer clinical treatments. In this research, miR-199a-5p was seen lowly expressed in NSCLC sera samples. miR-199a-5p suppressed the cell proliferation, migration and arrested cell cycle in NSCLC cell lines. The results showed that SLC2A1 (glucose transporter 1, GLUT1) was a direct target of miR-199a-5p. Downregulation of SLC2A1 could not only inhibit cell proliferation, migration and cell cycle, but also promote cell apoptosis. The data suggests that miR-199a-5p can inhibit glucose metabolism in NSCLC by targeting SLC2A1.This study proves that miR-199a-5p / SLC2A1 can play an essential role in the development of NSCLC by targeting SLC2A1. It puts forward a new approach for clinical treatments of NSCLC.

Preclinical Molecular PET-CT Imaging Targeting CDCP1 in Colorectal Cancer

Colorectal cancer (CRC) is the third most common malignancy in the world, with 22% of patients presenting with metastatic disease and a further 50% destined to develop metastasis. Molecular imaging uses antigen-specific ligands conjugated to radionuclides to detect and characterise primary cancer and metastases. Expression of the cell surface protein CDCP1 is increased in CRC, and here we sought to assess whether it is a suitable molecular imaging target for the detection of this cancer. CDCP1 expression was assessed in CRC cell lines and a patient-derived xenograft to identify models suitable for evaluation of radio-labelled 10D7, a CDCP1-targeted, high-affinity monoclonal antibody, for preclinical molecular imaging. Positron emission tomography-computed tomography was used to compare zirconium-89 (⁸⁹Zr)-10D7 avidity to a nonspecific, isotype control ⁸⁹Zr-labelled IgGκ1 antibody. The specificity of CDCP1-avidity was further confirmed using CDCP1 silencing and blocking models. Our data indicate high avidity and specificity for of ⁸⁹Zr-10D7 in CDCP1 expressing tumors at. Significantly higher levels than normal organs and blood, with greatest tumor avidity observed at late imaging time points. Furthermore, relatively high avidity is detected in high CDCP1 expressing tumors, with reduced avidity where CDCP1 expression was knocked down or blocked. The study supports CDCP1 as a molecular imaging target for CRC in preclinical PET-CT models using the radioligand ⁸⁹Zr-10D7.

Design, Synthesis and Binding Affinity Evaluation of Cytochrome P450 1B1 Targeted Chelators

BACKGROUND

Cytochrome P450 1B1 (CYP1B1) is specifically expressed in a variety of tumors which makes it a promise imaging target of tumor.

OBJECTIVE

We aimed to design and synthesize CYP1B1 targeted chelators for the potential application in positron emission tomography (PET) imaging of tumor.

METHODS

1,4,7-triazacyclononane-1,4-diiacetic acid (NODA) was connected to the CYP1B1 selective inhibitor we developed before through polyethylene glycol (PEG) linkers with different lengths. The inhibitory activities of chelators 6a-c against CYP1 family were evaluated by 7-ethoxyresorufin o-deethylation (EROD) assay. The manual docking between the chelators and the CYP1B1 are conducted subsequently. To determine the binding affinities of 6a-c to CYP1B1 in cells, we further performed a competition study at the cell level.

RESULTS

Among three chelators, 6a with the shortest linker showed the best inhibitory activity against CYP1B1. In the following molecular simulation study, protein-inhibitor complex of 6a showed the nearest F-heme distance which is consistent with the results of enzymatic assay. Finally, the cell based competitive assay proved the binding affinity of 6a-c to CYP1B1 enzyme.

CONCLUSION

We designed and synthesized a series of chelators which can bind to CYP1B1 enzyme in cancer cells.To our knowledge, this work is the first attempt to construct CYP1B1 targeted chelators for radiolabeling and we hope it will prompt the application of CYP1B1 imaging in tumor detection.

The Future of Nuclear Medicine as an Independent Specialty

In this article, we provide an overview of established and emerging conventional nuclear medicine and PET imaging biomarkers, as the diagnostic nuclear medicine portfolio is rapidly expanding. Next, we review briefly nuclear theranostic approaches that have already entered or are about to enter clinical routine. Using some approximations and taking into account emerging applications, we also provide some simplified business forecasts for nuclear theranostics. We argue that an optimistic outlook by the nuclear medicine community is crucial to the growth of the specialty and emphasize the urgent need for training adaptations.

Ultra-compact, automated microdroplet radiosynthesizer

Application of microfluidics offers numerous advantages in the field of radiochemistry and could enable dramatic reductions in the cost of producing radiotracers for positron emission tomography (PET). Droplet-based microfluidics, in particular, requires only microgram quantities of expensive precursors and reagents (compared to milligram used in conventional radiochemistry systems), and occupies a more compact footprint (potentially eliminating the need for specialized shielding facilities, i.e. hot cells). However, the reported platforms for droplet radiosynthesis have several drawbacks, including high cost/complexity of microfluidic reactors, requirement for manual intervention (e.g. for adding reagents), or difficulty in precise control of droplet processes. We describe here a platform based on a particularly simple chip, where reactions take place atop a hydrophobic substrate patterned with a circular hydrophilic liquid trap. The overall supporting hardware (heater, rotating carousel of reagent dispensers, etc.) is very simple and the whole system could be packaged into a very compact format (about the size of a coffee cup). We demonstrate the consistent synthesis of [18F]fallypride with high yield, and show that protocols optimized using a high-throughput optimization platform we have developed can be readily translated to this device with no changes or re-optimization. We are currently exploring the use of this platform for routine production of a variety of 18F-labeled tracers for preclinical imaging and for production of tracers in clinically-relevant amounts by integrating the system with an upstream radionuclide concentrator.

Transitioning from Radiology Training to Academic Faculty: Defining Your Role and Interests

Transitioning from radiology training to academic faculty presents many challenges. In this review, we discuss strategies to navigate this process and to facilitate success through appropriate selection of career tracks. Various modern avenues include roles as a Clinician-Educator, Clinician-Investigator, and Clinician-Administrator. Selection of the appropriate career track based on personal interests and institutional culture is critical for early and long-term career satisfaction.

Noninvasive Imaging of Drug-Induced Liver Injury with 18F-DFA PET

Drug-induced liver failure is a significant indication for a liver transplant, and unexpected liver toxicity is a major reason that otherwise effective therapies are removed from the market. Various methods exist for monitoring liver injury but are often inadequate to predict liver failure. New diagnostic tools are needed. Methods: We evaluate in a preclinical model whether 18F-2-deoxy-2-fluoroarabinose (18F-DFA), a PET radiotracer that measures the ribose salvage pathway, can be used to monitor acetaminophen-induced liver injury and failure. Mice treated with vehicle, 100, 300, or 500 mg/kg acetaminophen for 7 or 21 h were imaged with 18F-FDG and 18F-DFA PET. Hepatic radiotracer accumulation was correlated to survival and percentage of nonnecrotic tissue in the liver. Mice treated with acetaminophen and vehicle or N-acetylcysteine were imaged with 18F-DFA PET. 18F-DFA accumulation was evaluated in human hepatocytes engrafted into the mouse liver. Results: We show that hepatic 18F-DFA accumulation is 49%-52% lower in mice treated with high-dose acetaminophen than in mice treated with low-dose acetaminophen or vehicle. Under these same conditions, hepatic 18F-FDG accumulation was unaffected. At 21 h after acetaminophen treatment, hepatic 18F-DFA accumulation can distinguish mice that will succumb to the liver injury from those that will survive it (6.2 vs. 9.7 signal to background, respectively). Hepatic 18F-DFA accumulation in this model provides a tomographic representation of hepatocyte density in the liver, with a R2 between hepatic 18F-DFA accumulation and percentage of nonnecrotic tissue of 0.70. PET imaging with 18F-DFA can be used to distinguish effective from ineffective resolution of acetaminophen-induced liver injury with N-acetylcysteine (15.6 vs. 6.2 signal to background, respectively). Human hepatocytes, in culture or engrafted into a mouse liver, have levels of ribose salvage activity similar to those of mouse hepatocytes. Conclusion: Our findings suggest that PET imaging with 18F-DFA can be used to visualize and quantify drug-induced acute liver injury and may provide information on the progression from liver injury to hepatic failure.

Novel therapeutic strategy for cancer and autoimmune conditions: Modulating cell metabolism and redox capacity

Dysregulation of cell metabolism and redox balance is implicated in the pathogenesis and progression of cancer and autoimmune diseases. Because the cell proliferation and apoptotic regulatory pathways are interconnected with metabolic and redox signalling pathways, the current mono-target treatment is ineffective, and multi-drug resistance remains common. Complex diseases are often implicated in a network-based context of pathology; therefore, a new holistic intervention approach is required to block multi-crosstalk in such complicated circumstances. The use of therapeutic agents isolated from herbs to holistically modulate metabolism and redox state has been shown to relieve carcinoma growth and the inflammatory response in autoimmune disorders. Multiple clinically applied or novel herbal chemicals with metabolic and redox modulatory capacity as well as low toxicity have recently been identified. Moreover, new metabolic targets and mechanisms of drug action have been discovered, leading to the exploration of new pathways for drug repositioning, clinical biomarker spectra, clinical treatment strategies and drug development. Taken together with multiple supporting examples, the modulation of cell metabolism and the redox capacity using herbal chemicals is emerging as a new, alternative strategy for the holistic treatment of cancer and autoimmune disorders. In the future, the development of new diagnostic tools based on the detection of metabolic and redox biomarkers, reformulation of optimized herbal compositions using artificial intelligence, and the combination of herbs with mono-targeting drugs will reveal new potential for clinical application.

Correcting for targeted and control agent signal differences in paired-agent molecular imaging of cancer cell-surface receptors

Paired-agent kinetic modeling protocols provide one means of estimating cancer cell-surface receptors with in vivo molecular imaging. The protocols employ the coadministration of a control imaging agent with one or more targeted imaging agent to account for the nonspecific uptake and retention of the targeted agent. These methods require the targeted and control agent data be converted to equivalent units of concentration, typically requiring specialized equipment and calibration, and/or complex algorithms that raise the barrier to adoption. This work evaluates a kinetic model capable of correcting for targeted and control agent signal differences. This approach was compared with an existing simplified paired-agent model (SPAM), and modified SPAM that accounts for signal differences by early time point normalization of targeted and control signals (SPAMPN). The scaling factor model (SPAMSF) outperformed both SPAM and SPAMPN in terms of accuracy and precision when the scale differences between targeted and imaging agent signals (α) were not equal to 1, and it matched the performance of SPAM for α  =  1. This model could have wide-reaching implications for quantitative cancer receptor imaging using any imaging modalities, or combinations of imaging modalities, capable of concurrent detection of at least two distinct imaging agents (e.g., SPECT, optical, and PET/MR).

18F-FAC PET Selectively Images Liver-Infiltrating CD4 and CD8 T Cells in a Mouse Model of Autoimmune Hepatitis

Immune cell-mediated attack on the liver is a defining feature of autoimmune hepatitis and hepatic allograft rejection. Despite an assortment of diagnostic tools, invasive biopsies remain the only method for identifying immune cells in the liver. We evaluated whether PET imaging with radiotracers that quantify immune activation (¹⁸F-FDG and ¹⁸F-1-(2'-deoxy-2'-fluoro-arabinofuranosyl)cytosine [¹⁸F-FAC]) and hepatocyte biology (¹⁸F-2-deoxy-2-fluoroarabinose [¹⁸F-DFA]) can visualize and quantify liver-infiltrating immune cells and hepatocyte inflammation, respectively, in a preclinical model of autoimmune hepatitis. Methods: Mice treated with concanavalin A (ConA) to induce a model of autoimmune hepatitis or vehicle were imaged with ¹⁸F-FDG, ¹⁸F-FAC, and ¹⁸F-DFA PET. Immunohistochemistry, digital autoradiography, and ex vivo accumulation assays were used to localize areas of altered radiotracer accumulation in the liver. For comparison, mice treated with an adenovirus to induce a viral hepatitis were imaged with ¹⁸F-FDG, ¹⁸F-FAC, and ¹⁸F-DFA PET. ¹⁸F-FAC PET was performed on mice treated with ConA and vehicle or with ConA and dexamethasone. Biopsy samples of patients with autoimmune hepatitis were immunostained for deoxycytidine kinase. Results: Hepatic accumulation of ¹⁸F-FDG and ¹⁸F-FAC was 173% and 61% higher, respectively, and hepatic accumulation of ¹⁸F-DFA was 41% lower, in a mouse model of autoimmune hepatitis than in control mice. Increased hepatic ¹⁸F-FDG accumulation was localized to infiltrating leukocytes and inflamed sinusoidal endothelial cells, increased hepatic ¹⁸F-FAC accumulation was concentrated in infiltrating CD4 and CD8 cells, and decreased hepatic ¹⁸F-DFA accumulation was apparent in hepatocytes throughout the liver. In contrast, viral hepatitis increased hepatic ¹⁸F-FDG accumulation by 109% and decreased hepatic ¹⁸F-DFA accumulation by 20% but had no effect on hepatic ¹⁸F-FAC accumulation (nonsignificant 2% decrease). ¹⁸F-FAC PET provided a noninvasive biomarker of the efficacy of dexamethasone for treating the autoimmune hepatitis model. Infiltrating leukocytes in liver biopsy samples from patients with autoimmune hepatitis express high levels of deoxycytidine kinase, a rate-limiting enzyme in the accumulation of ¹⁸F-FAC. Conclusion: Our data suggest that PET can be used to noninvasively visualize activated leukocytes and inflamed hepatocytes in a mouse model of autoimmune hepatitis.

Cytochrome P450 1B1 promotes cancer cell survival via specificity protein 1 (Sp1)-mediated suppression of death receptor 4

Cytochrome P450 1B1 (CYP1B1), a well-known oncogene, has garnered wide attention because of its tumor-specific expression pattern and actions as a carcinogenic factor. Although CYP1B1 might play a crucial role in carcinogenesis, the detailed molecular mechanisms underlying oncogenic involvement in cancer development remain unclear. The present study investigated the manner in which CYP1B1 promotes survival of various cancer cells. Treatment with 2,2',4,6'-tetramethoxystilbene (TMS), a specific CYP1B1 inhibitor, significantly inhibited cell viability in human breast cancer and leukemia cell lines, including MCF-7, MDA-MB-231, HL-60, and U937 cells. In order to characterize the cellular functions of CYP1B1 associated with cancer cell survival, the relationship between this oncogene and death receptor 4 (DR4) was determined. Following induction or inhibition of CYP1B1, mRNA and protein expression levels of DR4 were measured, and this oncogene was found to significantly repress DR4 mRNA and protein expression. Further, the suppression of DR4 by CYP1B1 was restored with 5-aza-2'-deoxycytidine (5-aza-dC), a DNA methyltransferase inhibitor, indicating that DNA methylation may be involved in CYP1B1-mediated DR4 inhibition. Methylation-specific polymerase chain reaction (PCR) in CYP1B1-overexpressed HL-60 cells revealed that this oncogene induced hypermethylation on DR4 promoter. Interestingly, data showed that DR4 suppression of CYP1B1 is mediated by the DNA-binding ability of specificity protein 1 (Sp1). These findings suggest that CYP1B1 promotes cancer cell survival through involvement of DNA methylation-mediated DR4 inhibition and that Sp1 may act as key mediator required for oncogenic action.

Precision Medicine in Pediatric Neurooncology: A Review

Central nervous system tumors are the leading cause of cancer related death in children. Despite much progress in the field of pediatric neurooncology, modern combination treatment regimens often result in significant late effects, such as neurocognitive deficits, endocrine dysfunction, secondary malignancies, and a host of other chronic health problems. Precision medicine strategies applied to pediatric neurooncology target specific characteristics of individual patients' tumors to achieve maximal killing of neoplastic cells while minimizing unwanted adverse effects. Here, we review emerging trends and the current literature that have guided the development of new molecularly based classification schemas, promising diagnostic techniques, targeted therapies, and delivery platforms for the treatment of pediatric central nervous system tumors.

Cytoplasmic p53 couples oncogene-driven glucose metabolism to apoptosis and is a therapeutic target in glioblastoma

Cross-talk among oncogenic signaling and metabolic pathways may create opportunities for novel therapeutic strategies in cancer. Here we show that acute inhibition of EGFR-driven glucose metabolism induces minimal cell death, yet lowers the apoptotic threshold in a subset of patient-derived glioblastoma (GBM) cells. Mechanistic studies revealed that, following attenuated glucose consumption, Bcl-xL blocks cytoplasmic p53 from triggering intrinsic apoptosis. Consequently, pharmacological stabilization of p53 with the brain-penetrant small molecule, Idasanutlin, in combination with targeting EGFR-driven glucose metabolism promoted synthetic lethality in orthotopic xenograft models. Notably, neither inhibition of EGFR signaling, nor genetic analysis of EGFR, was sufficient to predict sensitivity to this new therapeutic combination. Conversely, rapid changes in ¹⁸F-fluorodeoxyglucose (¹⁸F-FDG) uptake using non-invasive positron emission tomography was an effective predictive biomarker of response in vivo. Together, these studies identify a critical link between oncogene signaling, glucose metabolism, and cytoplasmic p53, which could be exploited for combination therapy in GBM and potentially, other malignancies.