Visualising dual downregulation of insulin-like growth factor receptor-1 and vascular endothelial growth factor-A by heat shock protein 90 inhibition effect in triple negative breast cancer

Novel PET Imaging of Inflammatory Targets and Cells for the Diagnosis and Monitoring of Giant Cell Arteritis and Polymyalgia Rheumatica

Giant cell arteritis (GCA) and polymyalgia rheumatica (PMR) are two interrelated inflammatory diseases affecting patients above 50 years of age. Patients with GCA suffer from granulomatous inflammation of medium- to large-sized arteries. This inflammation can lead to severe ischemic complications (e.g., irreversible vision loss and stroke) and aneurysm-related complications (such as aortic dissection). On the other hand, patients suffering from PMR present with proximal stiffness and pain due to inflammation of the shoulder and pelvic girdles. PMR is observed in 40-60% of patients with GCA, while up to 21% of patients suffering from PMR are also affected by GCA. Due to the risk of ischemic complications, GCA has to be promptly treated upon clinical suspicion. The treatment of both GCA and PMR still heavily relies on glucocorticoids (GCs), although novel targeted therapies are emerging. Imaging has a central position in the diagnosis of GCA and PMR. While [18F]fluorodeoxyglucose (FDG)-positron emission tomography (PET) has proven to be a valuable tool for diagnosis of GCA and PMR, it possesses major drawbacks such as unspecific uptake in cells with high glucose metabolism, high background activity in several non-target organs and a decrease of diagnostic accuracy already after a short course of GC treatment. In recent years, our understanding of the immunopathogenesis of GCA and, to some extent, PMR has advanced. In this review, we summarize the current knowledge on the cellular heterogeneity in the immunopathology of GCA/PMR and discuss how recent advances in specific tissue infiltrating leukocyte and stromal cell profiles may be exploited as a source of novel targets for imaging. Finally, we discuss prospective novel PET radiotracers that may be useful for the diagnosis and treatment monitoring in GCA and PMR.

PKM2 Regulates HSP90-Mediated Stability of the IGF-1R Precursor Protein and Promotes Cancer Cell Survival during Hypoxia

Simple Summary

Generally, IGF-1R is overexpressed in most solid tumors, and its expression is significantly associated with poor prognosis in cancer patients. However, IGF-1R gene amplification events are extremely rare in tumors. It is, therefore, necessary to define the mechanism underlying IGR-1R overexpression to elucidate potential therapeutic targets. Our study, specifically, aimed to define the potential mechanisms associated with PKM2 function in regulating IGF-1R protein expression. PKM2 was found to be a non-metabolic protein that regulates HSP90 binding to and stabilizing the precursor IGF-1R protein, thereby promoting the basal level of mature IGF-1R protein. Consequently, PKM2 knockdown inhibits the activation of AKT, a downstream effector of IGF-1R signaling, and increases apoptosis during hypoxia. Our findings reveal a novel mechanism for regulating IGF-1R protein expression, thus suggesting PKM2 as a potential therapeutic target in cancers associated with aberrant IGF signaling.

Abstract

Insulin-like growth factor-1 receptor (IGF-1R), an important factor in promoting cancer cell growth and survival, is commonly upregulated in cancer cells. However, amplification of the IGF1R gene is extremely rare in tumors. Here, we have provided insights into the mechanisms underlying the regulation of IGF-1R protein expression. We found that PKM2 serves as a non-metabolic protein that binds to and increases IGF-1R protein expression by promoting the interaction between IGF-1R and heat-shock protein 90 (HSP90). PKM2 depletion decreases HSP90 binding to IGF-1R precursor, thereby reducing IGF-1R precursor stability and the basal level of mature IGF-1R. Consequently, PKM2 knockdown inhibits the activation of AKT, the key downstream effector of IGF-1R signaling, and increases apoptotic cancer cell death during hypoxia. Notably, we clinically verified the PKM2-regulated expression of IGF-1R through immunohistochemical staining in a tissue microarray of 112 lung cancer patients, demonstrating a significant positive correlation (r = 0.5208, p < 0.0001) between PKM2 and IGF-1R expression. Together, the results of a previous report demonstrated that AKT mediates PKM2 phosphorylation at serine-202; these results suggest that IGF-1R signaling and PKM2 mutually regulate each other to facilitate cell growth and survival, particularly under hypoxic conditions, in solid tumors with dysregulated IGF-1R expression.

Hsp90 Inhibitor; NVP-AUY922 in Combination with Doxorubicin Induces Apoptosis and Downregulates VEGF in MCF-7 Breast Cancer Cell Line

Objective:

Breast cancer is one of the most prevalent malignancies and leading causes of females’ mortality worldwide. Because of resistance to various treatment options, new treatments based on molecular targeting has introduced as noticeable strategies in cancer treatment. In this regard, heat shock protein 90 (Hsp90) inhibitors are proposed as effective anticancer drugs. The goal of the study was to utilize a combination of the doxorubicin (DOX) and NVP-AUY 922 on the MCF-7 breast cancer model to investigate the possible cytotoxic mechanisms.

Methods:

MCF-7 breast cancer cell line was prepared and treated with various concentrations of DOX and NVP-AUY922 in single-drug treatments. We investigated the growth-inhibitory pattern by MTT assay after continuous exposure to NVP-AUY922 and DOX in order to determine dose-response. Then the combinatorial effects were evaluated in concentrations of 0.5 × IC₅₀, 0.2 × IC₅₀, 1 × IC₅₀ and, 2 × IC₅₀ of each drugs. Based on MTT results of double combinations, low effective doses were selected for Real-time PCR [caspase3 and vascular endothelial growth factor (VEGF)] and caspase 3 enzyme activity.

Results:

A dose-dependent inhibitory effects were presented with increasing the doses of both drugs in single treatments. The upregulation of caspase 3 and downregulation of VEGF mRNA were observed in double combinations of NVP-AUY922 and DOX versus single treatments. Also, in these combinations in low doses of examined drugs (0.5 × IC₅₀, 0.2 × IC₅₀), higher caspase 3 activity were presented in comparison to single treatments (p<0.05).

Conclusions:

Our findings indicate an effective action of NVP-AUY922 in combined with DOX in this cell line. These results can predict the treatment outcome in this model.

ImmunoPET: Concept, Design, and Applications

Immuno-positron emission tomography (immunoPET) is a paradigm-shifting molecular imaging modality combining the superior targeting specificity of monoclonal antibody (mAb) and the inherent sensitivity of PET technique. A variety of radionuclides and mAbs have been exploited to develop immunoPET probes, which has been driven by the development and optimization of radiochemistry and conjugation strategies. In addition, tumor-targeting vectors with a short circulation time (e.g., Nanobody) or with an enhanced binding affinity (e.g., bispecific antibody) are being used to design novel immunoPET probes. Accordingly, several immunoPET probes, such as 89Zr-Df-pertuzumab and 89Zr-atezolizumab, have been successfully translated for clinical use. By noninvasively and dynamically revealing the expression of heterogeneous tumor antigens, immunoPET imaging is gradually changing the theranostic landscape of several types of malignancies. ImmunoPET is the method of choice for imaging specific tumor markers, immune cells, immune checkpoints, and inflammatory processes. Furthermore, the integration of immunoPET imaging in antibody drug development is of substantial significance because it provides pivotal information regarding antibody targeting abilities and distribution profiles. Herein, we present the latest immunoPET imaging strategies and their preclinical and clinical applications. We also emphasize current conjugation strategies that can be leveraged to develop next-generation immunoPET probes. Lastly, we discuss practical considerations to tune the development and translation of immunoPET imaging strategies.

Initial Clinical Results of a Novel Immuno-PET Theranostic Probe in Human Epidermal Growth Factor Receptor 2-Negative Breast Cancer

This prospective study evaluated the imaging performance of a novel pretargeting immunologic PET (immuno-PET) method in patients with human epidermal growth factor receptor 2 (HER2)-negative, carcinoembryonic antigen (CEA)-positive metastatic breast cancer, compared with CT, bone MRI, and ¹⁸F-FDG PET. Methods: Twenty-three patients underwent whole-body immuno-PET after injection of 150 MBq of ⁶⁸Ga-IMP288, a histamine-succinyl-glycine peptide given after initial targeting of a trivalent anti-CEA, bispecific, antipeptide antibody. The gold standards were histology and imaging follow-up. Tumor SUVs (SUV_max and SUV_mean) were measured, and tumor burden was analyzed using total tumor volume and total lesion activity. Results: The total lesion sensitivity of immuno-PET and ¹⁸F-FDG PET were 94.7% (1,116/1,178) and 89.6% (1,056/1,178), respectively. Immuno-PET had a somewhat higher sensitivity than CT or ¹⁸F-FDG PET in lymph nodes (92.4% vs. 69.7% and 89.4%, respectively) and liver metastases (97.3% vs. 92.1% and 94.8%, respectively), whereas sensitivity was lower for lung metastases (48.3% vs. 100% and 75.9%, respectively). Immuno-PET showed higher sensitivity than MRI or ¹⁸F-FDG PET for bone lesions (95.8% vs. 90.7% and 89.3%, respectively). In contrast to ¹⁸F-FDG PET, immuno-PET disclosed brain metastases. Despite equivalent tumor SUV_max, SUV_mean, and total tumor volume, total lesion activity was significantly higher with immuno-PET than with ¹⁸F-FDG PET (P = 0.009). Conclusion: Immuno-PET using anti-CEA/anti-IMP288 bispecific antibody, followed by ⁶⁸Ga-IMP288, is a potentially sensitive theranostic imaging method for HER2-negative, CEA-positive metastatic breast cancer patients and warrants further research.

HSP90 inhibitor PU-H71 increases radiosensitivity of breast cancer cells metastasized to visceral organs and alters the levels of inflammatory mediators

Heat shock protein 90 (HSP90) inhibitors are considered as new radiosensitizing agents. PU-H71, a novel HSP90 inhibitor, is under evaluation for the treatment of advanced cancer. It is however not known whether PU-H71 alters radiosensitivity of metastatic breast cancer. Hence, we here evaluated mechanisms of possible anti-tumoral and radiosensitizing effects of PU-H71 on breast carcinoma cells metastasized to vital organs such as the liver and brain. The effect of PU-H71 on proliferation of breast carcinoma cells was determined using 4T1 cells and its brain (4TBM), liver (4TLM), and heart (4THM) metastatic subsets as well as non-metastatic 67NR cells. Changes in radiation sensitivity were determined by clonogenic assays. Changes in client proteins and levels of angiogenic and inflammatory mediators from these cancer cell cultures and ex vivo cultures were detected. PU-H71 alone inhibited ERK1/2, p38, and Akt activation and reduced N-cadherin and HER2 which further documented the anti-tumoral effects of PU-H71. The combination of PU-H71 and radiotherapy induced cytotoxic effect than PU-H71 alone, and PU-H71 showed a radiosensitizing effect in vitro. On the other hand, PU-H71 and radiation co-treatment increased p38 phosphorylation which is one of the hallmarks of inflammatory response. Accordingly, IL-6 secretion was increased following PU-H71 and radiotherapy co-treatment ex vivo. Levels of angiogenic and inflammatory factors such as MIP-2, SDF-1, and VEGF were increased under in vitro conditions but not under ex vivo conditions. These results demonstrated for the first time that PU-H71 enhances therapeutic effects of radiotherapy especially in highly metastatic breast carcinoma but a possible increase in inflammatory response should also be considered.

Recent therapeutic trends and promising targets in triple negative breast cancer

Breast cancer accounts for 25% of all types of cancer in women, and triple negative breast cancer (TNBC) comprises around 15~20% of breast cancers. Conventional chemotherapy and radiation are the primary systemic therapeutic strategies; no other FDA-approved targeted therapies are yet available as for TNBC. TNBC is generally characterized by a poor prognosis and high rates of proliferation and metastases. Due to these aggressive features and lack of targeted therapies, numerous attempts have been made to discover viable molecular targets for TNBC. Massive cohort studies, clinical trials, and in-depth analyses have revealed diverse molecular alterations in TNBC; however, controversy exists as to whether many of these changes are beneficial or detrimental in caner progression. Here we review the complicated tumorigenic processes and discuss critical findings and therapeutic trends in TNBC with a focus on promising therapeutic approaches, the clinical trials currently underway, and potent experimental compounds under preclinical and evaluation.

Cytotoxicity of eupatorin in MCF-7 and MDA-MB-231 human breast cancer cells via cell cycle arrest, anti-angiogenesis and induction of apoptosis

Eupatorin has been reported with in vitro cytotoxic effect on several human cancer cells. However, reports on the mode of action and detail mechanism of eupatorin in vitro in breast cancer disease are limited. Hence, eupatorin's effect on the human breast carcinoma cell line MCF-7 and MDA-MB-231 was investigated. MTT assay showed that eupatorin had cytotoxic effects on MCF-7 and MDA-MB-231 cells but was non-toxic to the normal cells of MCF-10a in a time-dose dependent manner. At 24 h, the eupatorin showed mild cytotoxicity on both MCF-7 and MDA-MB-231 cells with IC50 values higher than 20 μg/mL. After 48 h, eupatorin at 5 μg/mL inhibited the proliferation of MCF-7 and MDA-MB-231 cells by 50% while the IC50 of MCF-10a was significantly (p < 0.05) high with 30 μg/mL. The concentration of eupatorin at 5 μg/mL induced apoptosis mainly through intrinsic pathway by facilitating higher fold of caspase 9 compared to caspase 8 at 48 h. The cell cycle profile also showed that eupatorin (5 μg/mL) exerted anti-proliferation activity with the cell cycle arrest of MCF-7 and MDA-MB-231 cells at sub Gθ/G1 in a time-dependent manner. In addition, wound healing assay showed an incomplete wound closure of scratched MDA-MB-231 cells, and more than 60% of the MDA-MB-231 cells were prevented to migrate and invade the membrane in the Boyden chamber after 24 h. Eupatorin also inhibited angiogenic sprouting of new blood vessels in ex vivo mouse aorta ring assay. In gene expression assay, eupatorin up-regulated pro-apoptotic genes such as Bak1, HIF1A, Bax, Bad, cytochrome c and SMAC/Diablo and blocked the Phospho-Akt pathway. In conclusion, eupatorin is a potent candidate to induce apoptosis and concurrently inhibit the invasion, migration and angiogenesis of MDA-MB-231 and MCF-7 cells through inhibition of Phospho-Akt pathway and cell cycle blockade.

89Zr-Onartuzumab PET imaging of c-MET receptor dynamics

PURPOSE

c-MET and its ligand hepatocyte growth factor are often dysregulated in human cancers. Dynamic changes in c-MET expression occur and might predict drug efficacy or emergence of resistance. Noninvasive visualization of c-MET dynamics could therefore potentially guide c-MET-directed therapies. We investigated the feasibility of 89Zr-labelled one-armed c-MET antibody onartuzumab PET for detecting relevant changes in c-MET levels induced by c-MET-mediated epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor erlotinib resistance or heat shock protein-90 (HSP90) inhibitor NVP-AUY-922 treatment in human non-small-cell lung cancer (NSCLC) xenografts.

METHODS

In vitro membrane c-MET levels were determined by flow cytometry. HCC827ErlRes, an erlotinib-resistant clone with c-MET upregulation, was generated from the exon-19 EGFR-mutant human NSCLC cell line HCC827. Mice bearing HCC827 and HCC827ErlRes tumours in opposite flanks underwent 89Zr-onartuzumab PET scans. The HCC827-xenografted mice underwent 89Zr-onartuzumab PET scans before treatment and while receiving biweekly intraperitoneal injections of 100 mg/kg NVP-AUY-922 or vehicle. Ex vivo, tumour c-MET immunohistochemistry was correlated with the imaging results.

RESULTS

In vitro, membrane c-MET was upregulated in HCC827ErlRes tumours by 213 ± 44% in relation to the level in HCC827 tumours, while c-MET was downregulated by 69 ± 9% in HCC827 tumours following treatment with NVP-AUY-922. In vivo, 89Zr-onartuzumab uptake was 26% higher (P < 0.05) in erlotinib-resistant HCC827ErlRes than in HCC827 xenografts, while HCC827 tumour uptake was 33% lower (P < 0.001) following NVP-AUY-922 treatment.

CONCLUSION

The results show that 89Zr-onartuzumab PET effectively discriminates relevant changes in c-MET levels and could potentially be used clinically to monitor c-MET status.

Harnessing Integrative Omics to Facilitate Molecular Imaging of the Human Epidermal Growth Factor Receptor Family for Precision Medicine

Cancer is a growing problem worldwide. The cause of death in cancer patients is often due to treatment-resistant metastatic disease. Many molecularly targeted anticancer drugs have been developed against 'oncogenic driver' pathways. However, these treatments are usually only effective in properly selected patients. Resistance to molecularly targeted drugs through selective pressure on acquired mutations or molecular rewiring can hinder their effectiveness. This review summarizes how molecular imaging techniques can potentially facilitate the optimal implementation of targeted agents. Using the human epidermal growth factor receptor (HER) family as a model in (pre)clinical studies, we illustrate how molecular imaging may be employed to characterize whole body target expression as well as monitor drug effectiveness and the emergence of tumor resistance. We further discuss how an integrative omics discovery platform could guide the selection of 'effect sensors' - new molecular imaging targets - which are dynamic markers that indicate treatment effectiveness or resistance.

Combination therapy approaches to target insulin-like growth factor receptor signaling in breast cancer

Insulin-like growth factor receptor (IGF1R) signaling as a therapeutic target has been widely studied and clinically tested. Despite the vast amount of literature supporting the biological role of IGF1R in breast cancer, effective clinical translation in targeting its activity as a cancer therapy has not been successful. The intrinsic complexity of cancer cell signaling mediated by many tyrosine kinase growth factor receptors that work together to modulate each other and intracellular downstream mediators in the cell highlights that studying IGF1R expression and activity as a prognostic factor and therapeutic target in isolation is certainly associated with problems. This review discusses the current literature and clinical trials associated with IGF-1 signaling and attempts to look at new ways of designing novel IGF1R-directed breast cancer therapy approaches to target its activity 
and/or intracellular downstream signaling pathways in IGF1R-expressing breast cancers.

Heat shock protein 90 inhibitors induce functional inhibition of human natural killer cells in a dose-dependent manner

Heat shock protein 90 (Hsp90) is a ubiquitously expressed ATP-dependent molecular chaperone across all species that helps to the correct the folding of many proteins related to important signaling pathways. Tumor cells expressing Hsp90 have more ATP-binding affinity than normal cells. Many correlative inhibitors have been developed to promising anti-tumor strategies and have been evaluated in clinical trials. However, the effect of Hsp90 inhibitors on immunocytes cannot be ignored. Natural killer (NK) cells are key components of the innate immune system that play a pivotal role in tumor surveillance. The present study has investigated the potential effect of four Hsp90 inhibitors (NVP-AUY922, BIIB021, 17-DMAG, and SNX-2112) on human primary NK cells. The viability, cytotoxicity, apoptosis, phenotype, and cytokine secretion of NK cells after inhibitor treatment were assessed. The results of this study demonstrated that the inhibitors had negative effects on NK cell activity in a dose-dependent manner. The four inhibitors significantly reduced the cytotoxicity of the NK cells by decreasing viability, inducing apoptosis and down-regulating the expression of cytokines and functional receptors. These findings suggest that more attention should be given to the effect of Hsp90 inhibitors on NK cell function during clinical trials and also represent a potential immunosuppressant strategy.

Optical innovations in surgery

BACKGROUND

In the past decade, there has been a major drive towards clinical translation of optical and, in particular, fluorescence imaging in surgery. In surgical oncology, radical surgery is characterized by the absence of positive resection margins, a critical factor in improving prognosis. Fluorescence imaging provides the surgeon with reliable and real-time intraoperative feedback to identify surgical targets, including positive tumour margins. It also may enable decisions on the possibility of intraoperative adjuvant treatment, such as brachytherapy, chemotherapy or emerging targeted photodynamic therapy (photoimmunotherapy).

METHODS

This article reviews the use of optical imaging for intraoperative guidance and decision-making.

RESULTS

Image-guided cancer surgery has the potential to be a powerful tool in guiding future surgical care. Photoimmunotherapy is a theranostic concept (simultaneous diagnosis and treatment) on the verge of clinical translation, and is highlighted as an effective combination of image-guided surgery and intraoperative treatment of residual disease. Multispectral optoacoustic tomography, a technique complementary to optical image-guided surgery, is currently being tested in humans and is anticipated to have great potential for perioperative and postoperative application in surgery.

CONCLUSION

Significant advances have been achieved in real-time optical imaging strategies for intraoperative tumour detection and margin assessment. Optical imaging holds promise in achieving the highest percentage of negative surgical margins and in early detection of micrometastastic disease over the next decade.

ImmunoPET of tissue factor expression in triple-negative breast cancer with a radiolabeled antibody Fab fragment

PURPOSE

To date, there is no effective therapy for triple-negative breast cancer (TNBC), which has a dismal clinical outcome. Upregulation of tissue factor (TF) expression leads to increased patient morbidity and mortality in many solid tumor types, including TNBC. Our goal was to employ the Fab fragment of ALT-836, a chimeric anti-human TF mAb, for PET imaging of TNBC, which can be used to guide future TNBC therapy.

METHODS

ALT-836-Fab was generated by enzymatic papain digestion. SDS-PAGE and FACS studies were performed to evaluate the integrity and TF binding affinity of ALT-836-Fab before NOTA conjugation and (64)Cu-labeling. Serial PET imaging and biodistribution studies were carried out to evaluate the tumor targeting efficacy and pharmacokinetics in the MDA-MB-231 TNBC model, which expresses high levels of TF on the tumor cells. Blocking studies, histological assessment, as well as RT-PCR were performed to confirm TF specificity of (64)Cu-NOTA-ALT-836-Fab.

RESULTS

ALT-836-Fab was produced with high purity, which exhibited superb TF binding affinity and specificity. Serial PET imaging revealed rapid and persistent tumor uptake of (64)Cu-NOTA-ALT-836-Fab (5.1 ± 0.5 %ID/g at 24 h post-injection; n = 4) and high tumor/muscle ratio (7.0 ± 1.2 at 24 h post-injection; n = 4), several-fold higher than that of the blocking group and tumor models that do not express significant level of TF, which was confirmed by biodistribution studies. TF specificity of the tracer was also validated by histology and RT-PCR.

CONCLUSION

(64)Cu-NOTA-ALT-836-Fab exhibited prominent tissue factor targeting efficiency in MDA-MB-231 TNBC model. The use of a Fab fragment led to fast tumor uptake and good tissue/muscle ratio, which may be translated into same-day immunoPET imaging in the clinical setting to improve TNBC patient management.