CMKLR1-targeting peptide tracers for PET/MR imaging of breast cancer

Noninvasive assessment of the lung inflammation-fibrosis axis by targeted imaging of CMKLR1

Precision management of fibrotic lung diseases is challenging due to their diverse clinical trajectories and lack of reliable biomarkers for risk stratification and therapeutic monitoring. Here, we validated the accuracy of CMKLR1 as an imaging biomarker of the lung inflammation-fibrosis axis. By analyzing single-cell RNA sequencing datasets, we demonstrated CMKLR1 expression as a transient signature of monocyte-derived macrophages (MDMφ) enriched in patients with idiopathic pulmonary fibrosis (IPF). Consistently, we identified MDMφ as the major driver of the uptake of CMKLR1-targeting peptides in a murine model of bleomycin-induced lung fibrosis. Furthermore, CMKLR1-targeted positron emission tomography in the murine model enabled quantification and spatial mapping of inflamed lung regions infiltrated by CMKLR1-expressing macrophages and emerged as a robust predictor of subsequent lung fibrosis. Last, high CMKLR1 expression by bronchoalveolar lavage cells identified an inflammatory endotype of IPF with poor survival. Our investigation supports the potential of CMKLR1 as an imaging biomarker for endotyping and risk stratification of fibrotic lung diseases.

Targeting the Oxytocin Receptor for Breast Cancer Management: A Niche for Peptide Tracers

Breast cancer is a leading cause of death in women, and its management highly depends on early disease diagnosis and monitoring. This remains challenging due to breast cancer's heterogeneity and a scarcity of specific biomarkers that could predict responses to therapy and enable personalized treatment. This Perspective describes the diagnostic landscape for breast cancer management, molecular strategies targeting receptors overexpressed in tumors, the theranostic potential of the oxytocin receptor (OTR) as an emerging breast cancer target, and the development of OTR-specific optical and nuclear tracers to study, visualize, and treat tumors. A special focus is on the chemistry and pharmacology underpinning OTR tracer development, preclinical in vitro and in vivo studies, challenges, and future directions. The use of peptide-based tracers targeting upregulated receptors in cancer is a highly promising strategy complementing current diagnostics and therapies and providing new opportunities to improve cancer management and patient survival.

Increased Demand of Obese Women for Protectins, Maresin, and Resolvin D1 in the Last Trimester of Pregnancy

BACKGROUND

Pregnancy is a physiological state during which inflammation occurs. This complex biological response is necessary for the implantation process as well as delivery. In turn, its suppression during gestation favors the normal course of the pregnancy. Therefore, the presence of pro-resolving mediators, EPA and DHA derivatives, The aim of this study was to investigate the changes in the levels of anti-inflammatory resolvins and their precursors in different trimesters of pregnancy with consideration of the women's weight, including overweight and obese women before pregnancy.

METHODS

A total of 78 women participated in this study; the mean age and BMI before pregnancy were 32.3 ± 5.52 and 27.73 ± 6.13, respectively. The patients were divided into two groups, considering their BMI before pregnancy. The extraction of eicosanoids was performed by high-performance liquid chromatography. The results obtained were subjected to statistical analysis. The levels of all studied parameters showed statistically significant differences between the study group (SG) and the control group (CG) in the different trimesters of pregnancy. Over the course of pregnancy, the levels of protection (PDX), maresin, resolvins (RvD1, RvE1), and their precursors differed in relation to the trimester of pregnancy and the division into groups considering the correct body weight before pregnancy.

RESULTS

Overweight or obese women had significantly lower levels of RvE1 in the third trimester and their precursors compared to normal-weight women. While the levels of PDX and RvD1 were significantly higher, this may be due to both a lower intake of products rich in omega-3 fatty acids by obese women and an increased need of obese women's bodies to quench chronic inflammatory processes associated with obesity.

CONCLUSIONS

Both EPA and DHA derivatives are involved in calming down inflammation during pregnancy, which was observed.

Advances in PET/CT Imaging for Breast Cancer

One out of eight women will be affected by breast cancer during her lifetime. Imaging plays a key role in breast cancer detection and management, providing physicians with information about tumor location, heterogeneity, and dissemination. In this review, we describe the latest advances in PET/CT imaging of breast cancer, including novel applications of 18F-FDG PET/CT and the development and testing of new agents for primary and metastatic breast tumor imaging and therapy. Ultimately, these radiopharmaceuticals may guide personalized approaches to optimize treatment based on the patient's specific tumor profile, and may become a new standard of care. In addition, they may enhance the assessment of treatment efficacy and lead to improved outcomes for patients with a breast cancer diagnosis.

The role of Chemerin in human diseases

Chemerin is a protein encoded by the Rarres2 gene that acts through endocrine or paracrine regulation. Chemerin can bind to its receptor, regulate insulin sensitivity and adipocyte differentiation, and thus affect glucose and lipid metabolism. There is growing evidence that it also plays an important role in diseases such as inflammation and cancer. Chemerin has been shown to play a role in the pathogenesis of inflammatory and metabolic diseases caused by leukocyte chemoattractants in a variety of organs, but its biological function remains controversial. In conclusion, the exciting findings collected over the past few years clearly indicate that targeting Chemerin signaling as a biological target will be a major research goal in the future. This article reviews the pathophysiological roles of Chemerin in various systems and diseases,and expect to provide a rationale for its role as a clinical therapeutic target.

Molecular imaging of chemokine-like receptor 1 (CMKLR1) in experimental acute lung injury

The lack of techniques for noninvasive imaging of inflammation has challenged precision medicine management of acute respiratory distress syndrome (ARDS). Here, we determined the potential of positron emission tomography (PET) of chemokine-like receptor-1 (CMKLR1) to monitor lung inflammation in a murine model of lipopolysaccharide-induced injury. Lung uptake of a CMKLR1-targeting radiotracer, [⁶⁴Cu]NODAGA-CG34, was significantly increased in lipopolysaccharide-induced injury, correlated with the expression of multiple inflammatory markers, and reduced by dexamethasone treatment. Monocyte-derived macrophages, followed by interstitial macrophages and monocytes were the major CMKLR1-expressing leukocytes contributing to the increased tracer uptake throughout the first week of lipopolysaccharide-induced injury. The clinical relevance of CMKLR1 as a biomarker of lung inflammation in ARDS was confirmed using single-nuclei RNA-sequencing datasets which showed significant increases in CMKLR1 expression among transcriptionally distinct subsets of lung monocytes and macrophages in COVID-19 patients vs. controls. CMKLR1-targeted PET is a promising strategy to monitor the dynamics of lung inflammation and response to anti-inflammatory treatment in ARDS.

Chemerin Forms: Their Generation and Activity

Chemerin is the product of the RARRES2 gene which is secreted as a precursor of 143 amino acids. That precursor is inactive, but proteases from the coagulation and fibrinolytic cascades, as well as from inflammatory reactions, process the C-terminus of chemerin to first activate it and then subsequently inactivate it. Chemerin can signal via two G protein-coupled receptors, chem1 and chem2, as well as be bound to a third non-signaling receptor, CCRL2. Chemerin is produced by the liver and secreted into the circulation as a precursor, but it is also expressed in some tissues where it can be activated locally. This review discusses the specific tissue expression of the components of the chemerin system, and the role of different proteases in regulating the activation and inactivation of chemerin. Methods of identifying and determining the levels of different chemerin forms in both mass and activity assays are reviewed. The levels of chemerin in circulation are correlated with certain disease conditions, such as patients with obesity or diabetes, leading to the possibility of using chemerin as a biomarker.

Chemerin: A Functional Adipokine in Reproductive Health and Diseases

As a multifaceted adipokine, chemerin has been found to perform functions vital for immunity, adiposity, and metabolism through its three known receptors (chemokine-like receptor 1, CMKLR1; G-protein-coupled receptor 1, GPR1; C-C motif chemokine receptor-like 2, CCRL2). Chemerin and the cognate receptors are also expressed in the hypothalamus, pituitary gland, testis, ovary, and placenta. Accumulating studies suggest that chemerin participates in normal reproduction and underlies the pathological mechanisms of certain reproductive system diseases, including polycystic ovary syndrome (PCOS), preeclampsia, and breast cancer. Herein, we present a comprehensive review of the roles of the chemerin system in multiple reproductive processes and human reproductive diseases, with a brief discussion and perspectives on future clinical applications.

Chemerin - exploring a versatile adipokine

Chemerin is a small chemotactic protein and a key player in initiating the early immune response. As an adipokine, chemerin is also involved in energy homeostasis and the regulation of reproductive functions. Secreted as inactive prochemerin, it relies on proteolytic activation by serine proteases to exert biological activity. Chemerin binds to three distinct G protein-coupled receptors (GPCR), namely chemokine-like receptor 1 (CMKLR1, recently named chemerin₁), G protein-coupled receptor 1 (GPR1, recently named chemerin₂), and CC-motif chemokine receptor-like 2 (CCRL2). Only CMKLR1 displays conventional G protein signaling, while GPR1 only recruits arrestin in response to ligand stimulation, and no CCRL2-mediated signaling events have been described to date. However, GPR1 undergoes constitutive endocytosis, making this receptor perfectly adapted as decoy receptor. Here, we discuss expression pattern, activation, and receptor binding of chemerin. Moreover, we review the current literature regarding the involvement of chemerin in cancer and several obesity-related diseases, as well as recent developments in therapeutic targeting of the chemerin system.

A Chemerin Peptide Analog Stimulates Tumor Growth in Two Xenograft Mouse Models of Human Colorectal Carcinoma

Simple Summary

The chemoattractant adipokine chemerin has been found to be elevated in several types of cancer, including colorectal carcinoma. The functional role of chemerin in colorectal carcinoma, however, has not been elucidated to date. This study analyses the impact of the chemerin analog CG34 on proliferation, colony formation, and migration in the human colorectal cancer cell lines HCT116, HT29 and SW620. In addition, the effect of systemic CG34 treatment is investigated in two xenograft mouse models of colorectal cancer (HCT116-luc and HT29-luc). The results of this study suggest there is a stimulatory role of chemerin receptor activation on the growth of colorectal carcinoma.

Abstract

Background: Chemerin plasma concentration has been reported to be positively correlated with the risk of colorectal cancer. However, the potential regulation of CRC tumorigenesis and progression has not yet been investigated in an experimental setting. This study addresses this hypothesis by investigating proliferation, colony formation, and migration of CRC cell lines in vitro as well as in animal models. Methods: In vitro, microscopic assays to study proliferation, as well as a scratch-wound assay for migration monitoring, were applied using the human CRC cell lines HCT116, HT29, and SW620 under the influence of the chemerin analog CG34. The animal study investigated HCT116-luc and HT29-luc subcutaneous tumor size and bioluminescence during treatment with CG34 versus control, followed by an ex-vivo analysis of vessel density and mitotic activity. Results: While the proliferation of the three CRC cell lines in monolayers was not clearly stimulated by CG34, the chemerin analog promoted colony formation in three-dimensional aggregates. An effect on cell migration was not observed. In the treatment study, CG34 significantly stimulated both growth and bioluminescence signals of HCT116-luc and HT29-luc xenografts. Conclusions: The results of this study represent the first indication of a tumor growth-stimulating effect of chemerin signaling in CRC.

Cyclic Derivatives of the Chemerin C-Terminus as Metabolically Stable Agonists at the Chemokine-like Receptor 1 for Cancer Treatment

Chemerin is a small chemotactic protein and a modulator of the innate immune system. Its activity is mainly mediated by the chemokine-like receptor 1 (CMKLR1), a receptor expressed by natural killer cells, dendritic cells, and macrophages. Downregulation of chemerin is part of the immune evasion strategy exploited by several cancer types, including melanoma, breast cancer, and hepatocellular carcinoma. Administration of chemerin can potentially counteract these effects, but synthetically accessible, metabolically stable analogs are required. Other tumors display overexpression of CMKLR1, offering a potential entry point for targeted delivery of chemotherapeutics. Here, we present cyclic derivatives of the chemerin C-terminus (chemerin-9), the minimal activation sequence of chemerin. Chemerin-9 derivatives that were cyclized through positions four and nine retained activity while displaying full stability in blood plasma for more than 24 h. Therefore, these peptides could be used as a drug shuttle system to target cancer cells as demonstrated here by methotrexate conjugates.

Preclinical Advances in Theranostics for the Different Molecular Subtypes of Breast Cancer

Breast cancer is the most common cancer in women worldwide. The heterogeneity of breast cancer and drug resistance to therapies make the diagnosis and treatment difficult. Molecular imaging methods with positron emission tomography (PET) and single-photon emission tomography (SPECT) provide useful tools to diagnose, predict, and monitor the response of therapy, contributing to precision medicine for breast cancer patients. Recently, many efforts have been made to find new targets for breast cancer therapy to overcome resistance to standard of care treatments, giving rise to new therapeutic agents to offer more options for patients with breast cancer. The combination of diagnostic and therapeutic strategies forms the foundation of theranostics. Some of these theranostic agents exhibit high potential to be translated to clinic. In this review, we highlight the most recent advances in theranostics of the different molecular subtypes of breast cancer in preclinical studies.

Radiolabeled Peptides for SPECT and PET Imaging in the Detection of Breast Cancer: Preclinical and Clinical Perspectives

Breast cancer is the most common cancer in women worldwide. Due to the heterogeneous nature of breast cancer, the optimal treatment and expected response for each patient may not necessarily be universal. Molecular imaging techniques could play an important role in the early detection and targeted therapy evaluation of breast cancer. This review focuses on the development of peptides labeled with SPECT and PET radionuclides for breast cancer imaging. We summarized the current status of radiolabeled peptides for different receptors in breast cancer. The characteristics of radionuclides and major techniques for peptide labeling are also briefly discussed.

Shortwave Infrared-Emitting Theranostics for Breast Cancer Therapy Response Monitoring

Therapeutic drug monitoring (TDM) in cancer, while imperative, has been challenging due to inter-patient variability in drug pharmacokinetics. Additionally, most pharmacokinetic monitoring is done by assessments of the drugs in plasma, which is not an accurate gauge for drug concentrations in target tumor tissue. There exists a critical need for therapy monitoring tools that can provide real-time feedback on drug efficacy at target site to enable alteration in treatment regimens early during cancer therapy. Here, we report on theranostic optical imaging probes based on shortwave infrared (SWIR)-emitting rare earth-doped nanoparticles encapsulated with human serum albumin (abbreviated as ReANCs) that have demonstrated superior surveillance capability for detecting micro-lesions at depths of 1 cm in a mouse model of breast cancer metastasis. Most notably, ReANCs previously deployed for detection of multi-organ metastases resolved bone lesions earlier than contrast-enhanced magnetic resonance imaging (MRI). We engineered tumor-targeted ReANCs carrying a therapeutic payload as a potential theranostic for evaluating drug efficacy at the tumor site. In vitro results demonstrated efficacy of ReANCs carrying doxorubicin (Dox), providing sustained release of Dox while maintaining cytotoxic effects comparable to free Dox. Significantly, in a murine model of breast cancer lung metastasis, we demonstrated the ability for therapy monitoring based on measurements of SWIR fluorescence from tumor-targeted ReANCs. These findings correlated with a reduction in lung metastatic burden as quantified via MRI-based volumetric analysis over the course of four weeks. Future studies will address the potential of this novel class of theranostics as a preclinical pharmacological screening tool.

Multimodal Imaging of 2-Cycle PRRT with 177Lu-DOTA-JR11 and 177Lu-DOTATOC in an Orthotopic Neuroendocrine Xenograft Tumor Mouse Model

Peptide receptor radionuclide therapy (PRRT) using radiolabeled somatostatin receptor (SSTR) analogs is a common approach in advanced neuroendocrine neoplasms. Recently, SSTR antagonists have shown promising results for imaging and therapy due to a higher number of binding sites than in commonly used agonists. We evaluated PRRT with SSTR agonist ¹⁷⁷Lu-DOTATOC and antagonist ¹⁷⁷Lu-DOTA-JR11 longitudinally in an orthotopic murine pancreatic neuroendocrine neoplasm model expressing human SSTR2. Morphologic and metabolic changes during treatment were assessed using multimodal imaging, including hybrid PET/MRI and SPECT/CT. Methods: In vitro radioligand binding and internalization assays and cell-cycle analysis were performed. SSTR2-transfected BON cells (BON-SSTR2) were used for in vivo experiments. Tumor-bearing mice received 2 intravenous injections of 100 μL of saline, 30 MBq of ¹⁷⁷Lu-DOTATOC, or 20 MBq of ¹⁷⁷Lu-DOTA-JR11 with an interval of 3 wk. Weekly T2-weighted MRI was performed for tumor monitoring. Viability of the tumor tissue was assessed by ¹⁸F-FDG PET/MRI once after PRRT. Tumor and kidney uptake of the respective radiopharmaceuticals was measured 24 h after injection by SPECT/CT. Results: Compared with ¹⁷⁷Lu-DOTATOC, ¹⁷⁷Lu-DOTA-JR11 treatment resulted in an increased accumulation of cells in G2/M phase. Animals treated with the SSTR antagonist showed a significant reduction in tumor size (P < 0.001) and an increased median survival (207 d; interquartile range [IQR], 132-228) compared with ¹⁷⁷Lu-DOTATOC (126 d; IQR, 118-129). SPECT/CT revealed a 4-fold higher median tumor uptake for the antagonist and a 3-fold higher tumor-to-kidney ratio in the first treatment cycle. During the second therapy cycle, tumor uptake of ¹⁷⁷Lu-DOTATOC was significantly lower (P = 0.01) whereas ¹⁷⁷Lu-DOTA-JR11 uptake remained stable. Imaging of tumor morphology indicated comparatively larger necrotic fractions for ¹⁷⁷Lu-DOTA-JR11 despite further tumor growth. These results were confirmed by ¹⁸F-FDG PET, revealing the least amount of viable tumor tissue in ¹⁷⁷Lu-DOTA-JR11-treated animals, at 6.2% (IQR, 2%-23%). Conclusion: ¹⁷⁷Lu-DOTA-JR11 showed a higher tumor-to-kidney ratio and a more pronounced cytotoxic effect than did ¹⁷⁷Lu-DOTATOC. Additionally, tumor uptake was more stable over the course of 2 treatment cycles.