ACE2 abrogates tumor resistance to VEGFR inhibitors suggesting angiotensin-(1-7) as a therapy for clear cell renal cell carcinoma

Advanced progress of the relationship between renin-angiotensin-aldosterone system inhibitors and cancers

Hypertension and cancers are the most common causes of death in humans, as well as common co-diseases among elderly population. Studies have shown that hypertension is associated with carcinogenesis. The renin-angiotensin-aldosterone system (RAAS) is a crucial regulatory system of blood pressure, fluid, and electrolyte homeostasis, which plays an essential role in the pathogenesis of hypertension, whose mechanism is relatively clear. Studies have indicated that RAAS also widely exists in cancer tissues of different systems, which can affect the risk of cancers by stimulating cancer angiogenesis, participating in cancer-related oxidative stress, and regulating cancer-related immunity. Therefore, inhibiting RAAS activity seems beneficial to decreasing the risk of cancers. As one of the most commonly used antihypertensive drugs, RAAS inhibitors have been widely used in clinical practice. However, the conclusions of clinical studies on the relationship between RAAS inhibitors and cancers are not entirely consistent, which has been widely concerned by clinicians. The latest findings suggest that while RAAS inhibitors may reduce the risk of digestive cancers, respiratory cancers, urological cancers, gynecological cancers, and skin cancers, ACEIs may increase the risk of lung cancer, endometrial cancer, basal cell carcinoma, and squamous cell carcinoma. This article comprehensively reviews animal experiments, clinical studies, and meta-analyses on the relationship between RAAS inhibitors and cancers, to provide references for related studies in the future.

Novel curcumin-based analogues as potential VEGFR2 inhibitors with promising metallic loading nanoparticles: synthesis, biological evaluation, and molecular modelling investigation

VEGFR2 inhibition has been established as a therapeutic approach for managing cancer. A series of curcumin-based analogues were designed, synthesized, and screened for their anticancer activity against MCF-7 and HepG-2 cell lines and WISH normal cells. Compounds 4b, 4d, 4e, and 4f showed potent cytotoxicity against MCF-7 with IC50 values of 0.49, 0.14, 0.01, and 0.32 μM, respectively, compared to curcumin (IC50 = 13.8 μM) and sorafenib (IC50 = 2.13 μM). Interestingly, compound 4e, the most active compound, exhibited potent VEGFR2 inhibition with an IC50 value of 11.6 nM (96.5% inhibition) compared to sorafenib with an IC50 value of 30 nM (94.8% inhibition). Additionally, compound 4e significantly induced apoptotic cell death in MCF-7 cells by 41.1% compared to a control group (0.8%), halting cell division during the G2/M phase by 39.8% compared to the control (21.7%). Molecular docking-coupled dynamics simulations highlighted the bias of the VEGFR2 pocket towards compound 4e compared to other synthesized compounds. Predicting superior binding affinities and relevant interactions with the pocket's key residues recapitulated in vitro findings towards higher inhibition activity for compound 4e. Furthermore, compound 4e with adequate pharmacokinetic and drug-likeness profiles in terms of ADME and safety characteristics can serve as a promising clinical candidate for future lead optimization and development. Notably, 4e-Fe2O3-humic acid NPs exhibited potent cytotoxicity with IC50 values of 2.41 and 13.4 ng mL-1 against MCF-7 and HepG-2 cell lines, respectively. Hence, compound 4e and its Fe2O3-humic acid-NPs could be further developed as promising anti-breast cancer agents.

Radiotracers for Molecular Imaging of Angiotensin-Converting Enzyme 2

Angiotensin-converting enzymes (ACE) are well-known for their roles in both blood pressure regulation via the renin-angiotensin system as well as functions in fertility, immunity, hematopoiesis, and many others. The two main isoforms of ACE include ACE and ACE-2 (ACE2). Both isoforms have similar structures and mediate numerous effects on the cardiovascular system. Most remarkably, ACE2 serves as an entry receptor for SARS-CoV-2. Understanding the interaction between the virus and ACE2 is vital to combating the disease and preventing a similar pandemic in the future. Noninvasive imaging techniques such as positron emission tomography and single photon emission computed tomography could noninvasively and quantitatively assess in vivo ACE2 expression levels. ACE2-targeted imaging can be used as a valuable tool to better understand the mechanism of the infection process and the potential roles of ACE2 in homeostasis and related diseases. Together, this information can aid in the identification of potential therapeutic drugs for infectious diseases, cancer, and many ACE2-related diseases. The present review summarized the state-of-the-art radiotracers for ACE2 imaging, including their chemical design, pharmacological properties, radiochemistry, as well as preclinical and human molecular imaging findings. We also discussed the advantages and limitations of the currently developed ACE2-specific radiotracers.

PD1/PD-L1 blockade in clear cell renal cell carcinoma: mechanistic insights, clinical efficacy, and future perspectives

The advent of PD1/PD-L1 inhibitors has significantly transformed the therapeutic landscape for clear cell renal cell carcinoma (ccRCC). This review provides an in-depth analysis of the biological functions and regulatory mechanisms of PD1 and PD-L1 in ccRCC, emphasizing their role in tumor immune evasion. We comprehensively evaluate the clinical efficacy and safety profiles of PD1/PD-L1 inhibitors, such as Nivolumab and Pembrolizumab, through a critical examination of recent clinical trial data. Furthermore, we discuss the challenges posed by resistance mechanisms to these therapies and potential strategies to overcome them. We also explores the synergistic potential of combination therapies, integrating PD1/PD-L1 inhibitors with other immunotherapies, targeted therapies, and conventional modalities such as chemotherapy and radiotherapy. In addition, we examine emerging predictive biomarkers for response to PD1/PD-L1 blockade and biomarkers indicative of resistance, providing a foundation for personalized therapeutic approaches. Finally, we outline future research directions, highlighting the need for novel therapeutic strategies, deeper mechanistic insights, and the development of individualized treatment regimens. Our work summarizes the latest knowledge and progress in this field, aiming to provide a valuable reference for improving clinical efficacy and guiding future research on the application of PD1/PD-L1 inhibitors in ccRCC.

The Expression of Alamandine Receptor MrgD in Clear Cell Renal Cell Carcinoma Is Associated with a Worse Prognosis and Unfavorable Response to Antiangiogenic Therapy

Renal cell carcinoma (RCC) ranks among the most prevalent malignancies in Western countries, marked by its notable heterogeneity, which contributes to an unpredictable clinical trajectory. The insufficiency of dependable biomarkers adds complexity to assessing this tumor progression. Imbalances of several components of the intrarenal renin-angiotensin system (iRAS) significantly impact patient prognoses and responses to first-line immunotherapies. In this study, we analyzed the immunohistochemical expression of the Mas-related G-protein-coupled receptor D (MrgD), which recognizes the novel RAS peptide alamandine (ALA), in a series of 87 clear cell renal cell (CCRCCs), 19 papillary (PRCC), 7 chromophobe (ChRCC) renal cell carcinomas, and 11 renal oncocytomas (RO). MrgD was expressed in all the renal tumor subtypes, with a higher mean staining intensity in the PRCCs, ChRCCs, and ROs. A high expression of MrgD at the tumor center and at the infiltrative front of CCRCC tissues was significantly associated with a high histological grade, large tumor diameter, local invasion, and locoregional node and distant metastasis. Patients with worse 5-year cancer-specific survival and a poorer response to antiangiogenic tyrosine-kinase inhibitors (TKIs) showed higher MrgD expression at the center of their primary tumors. These findings suggest a possible role of MrgD in renal carcinogenetic processes. Further studies are necessary to unveil its potential as a novel biomarker for CCRCC prognosis and response to frontline therapies.

New Insights into the Link between SARS-CoV-2 Infection and Renal Cancer

Cancer has been described as a risk factor for greater susceptibility to SARS-CoV-2 infection and severe COVID-19, mainly for patients with metastatic disease. Conversely, to that reported for most solid and hematological malignancies, the few available clinical studies reported that the infection did not increase the risk of death in renal cancer patients. The expression on proximal tubular renal cells of the key players in cellular viral uptake, ACE2, TMPRSS2, and NRP1, seems to be the mechanism for the direct kidney injury seen in patients with COVID-19. Interestingly, data from The Cancer Genome Atlas and experimental analyses on various renal cancer cell lines demonstrated that the above-reported receptors/cofactors are maintained by renal cancer cells. However, whether SARS-CoV-2 infection directly kills renal cancer cells or generates enhanced immunogenicity is a question worth investigating. In addition, some researchers have further addressed the topic by studying the expression and prognostic significance of gene signatures related to SARS-CoV-2 infection in renal cancer patients. The emerging data highlights the importance of better understanding the existence of a link between renal cancer and COVID-19 since it could lead to the identification of new prognostic factors and the development of new therapeutic targets in the management of renal cancer patients.

A novel angiogenesis-related scoring model predicts prognosis risk and treatment responsiveness in diffuse large B-cell lymphoma

Diffuse large B cell lymphoma (DLBCL) is a highly heterogeneous disease with varying therapeutic responses and prognoses. Angiogenesis is a crucial factor in lymphoma growth and progression, but no scoring model based on angiogenesis-related genes (ARGs) has been developed for prognostic evaluation of DLBCL patients. In this study, we used univariate Cox regression to identify prognostic ARGs and found two distinct clusters of DLBCL patients in the GSE10846 dataset based on the expression of these prognostic ARGs. These two clusters had different prognoses and immune cell infiltration. Using LASSO regression analysis, we constructed a novel seven-ARG-based scoring model in GSE10846 dataset, and it was further validated in the GSE87371 dataset. The DLBCL patients were divided into high- and low-score groups based on the median risk score as a cut-off. The high-score group had a worse prognosis and showed higher expression of immune checkpoints, M2 macrophages, myeloid-derived suppressor cells, and regulatory T cells, indicating a stronger immunosuppressive environment. DLBCL patients in high-score group were resistant to doxorubicin and cisplatin, which are components of frequently used chemotherapy regimens, but more sensitive to gemcitabine and temozolomide. Using RT-qPCR, we found that two candidate risk genes, RAPGEF2 and PTGER2, were over-expressed in DLBCL tissues compared with control tissues. Taken together, the ARG-based scoring model provides a promising direction for the prognosis and immune status of DLBCL patients, and benefits the development of personalized treatment for DLBCL patients.

RUNX1 predicts poor prognosis and correlates with tumor progression in clear cell renal carcinoma

BACKGROUND

Runt-related transcription factor 1 (RUNX1), also called acute myeloid leukaemia 1, is a member of RUNX family of transcription factors. This family is composed of evolutionarily conserved transcription factors that function as critical lineage determinants in various tissues, however its function in cancer development and clinical significance in RCC are still unknown.

METHODS

We used paraffin-embedded tumor tissues from 100 patients and fresh-harvested and paired adjacent normal renal tissues from 15 RCC patients who underwent primary surgical resection in Xijing Hospital between 2018 and 2022. The expression level of RUNX1 was evaluated by immunohistochemistry and Western Blot. RUNX1 promoted tumor cells proliferation, migration and invasion were verified by CCK-8, wound-healing and transwell assays. Finally, we constructed a xenografts model of the 786-O cell lines to observe the effect of RUNX1 on tumorigenesis in vivo.

RESULTS

TCGA database showed higher RUNX1 expression levels in KIRC (kidney renal clear cell carcinoma). In overall survival analysis, RCC patients with higher RUNX1 expression level would have a shorter survival period than those with lower expression. Similarly, immunohistochemical results of our cohort also showed that RUNX1 was over-expression in cancer tissues than in corresponding non-cancer tissues. We also proved this result at protein level by western-blot. Meanwhile, prognostic and OS analyses of our cohort showed that the RUNX1 expression level was an individual prognostic factor in RCC patients. CCK-8, wound-healing and transwell assays proved that the overexpression of RUNX1 in Caki-1 cells promoted the proliferation, migration and invasion of the cells. Knocking down RUNX1 in 786-O cells inhibited the proliferation, migration and invasion of cells. The experimental results of xenografts model in nude mice showed that the knockdown of RUNX1 in 786-O cells slowed down the growth of tumor.

CONCLUSION

RUNX1 is a poor prognostic factor of clear cell renal carcinoma, which may provide a novel therapeutic target for ccRCC.

Caveolin-1-ACE2 axis modulates xenobiotic metabolism-linked chemoresistance in ovarian clear cell carcinoma

Among epithelial ovarian cancers, ovarian clear cell carcinoma (OCCC) remains markedly resistant to platinum-based chemotherapy, leading to poor clinical outcomes. In response to xenobiotic insults, caveolar platforms play crucial roles in modulating stress signaling responses in cancer cells. It has been hypothesized that caveolin-1 (Cav-1), a main component of the lipid raft, may regulate the response to platinum-based treatment in OCCC. The clinical transcriptomic evaluation demonstrated that high Cav-1 expression was positively associated with a favorable prognosis in patients with ovarian cancer. Cav-1 overexpression enhanced sensitivity to cisplatin (CDDP) treatment, whereas Cav-1 deficiency promoted chemoresistance in OCCC cells. Mechanistically, although Cav-1 counteracted angiotensin-converting enzyme 2 (ACE2) expression, ACE2 positively facilitated resistance to CDDP in OCCC cells. Furthermore, ACE2 restricted aryl hydrocarbon receptor expression and subsequent transcription of drug-metabolizing enzymes. Of note, ACE2 positively regulated the expression of the platinum-clearing enzyme CYP3A4. These findings suggest that the Cav-1-ACE2 axis modulates xenobiotic metabolism-linked chemoresistance in OCCC, predicting potential roles for the stress sentinel networks in oncogenic processes.

68Ga-cyc-DX600 PET/CT in ACE2-targeted tumor imaging

PURPOSE

For the tumor-specific ACE2 expression, this research aimed to establish and verify ACE2-targeted PET imaging in differentiating tumors with distinct ACE2 expression.

METHODS

68Ga-cyc-DX600 was synthesized as tracer of ACE2 PET. NOD-SCID mice were used to prepare the subcutaneous tumor models with HEK-293 or HEK-293T/hACE2 cells to verify ACE2 specificity, with other kinds of tumor cells to evaluate the diagnostic efficiency for ACE2 expression, additionally, immunohistochemical analysis and western blot were used to certify the findings on ACE2 PET, which was then performed on four cancer patients and compared with FDG PET.

RESULTS

The metabolic clearance of 68Ga-cyc-DX600 was initially completed in 60 min, realizing an ACE2-dependent and organ-specific background of ACE2 PET; meanwhile, tracer uptake of subcutaneous tumor models was of a definite dependence on ACE2 expression (r = 0.903, p < 0.05), and the latter served as the primary factor when ACE2 PET was used for the differential diagnosis of ACE2-related tumors. In pre-clinical practice, a comparable tumor-to-background ratio was acquired in ACE2 PET of a lung cancer patient at 50 and 80 min post injection; the quantitative values of ACE2 PET and FDG PET were negatively correlated (r =  - 0.971 for SUVmax, p = 0.006; r =  - 0.994 for SUVmean, p = 0.001) in an esophageal cancer patient, no matter the primary lesion or metastasis.

CONCLUSIONS

68Ga-cyc-DX600 PET was an ACE2-specific imaging for the differential diagnosis of tumors and added complementary value to conventional nuclear medicine diagnosis, such as FDG PET on glycometabolism.

Indoxyl Sulfate Promotes Metastatic Characteristics of Ovarian Cancer Cells via Aryl Hydrocarbon Receptor-Mediated Downregulation of the Mas Receptor

Although platinum-combination chemotherapy shows a high response rate at the primary site, epithelial ovarian cancer (EOC) treatment remains challenging because of tumor recurrence and metastasis. Recent studies have revealed that chemotherapy paradoxically promotes cancer cell survival, proliferation, and metastasis, although the reason for this remains unclear. The underlying molecular mechanisms that contribute to chemotherapy-induced metastasis need to be elucidated to establish effective therapeutic strategies. Acute kidney injury is a known side effect of cisplatin treatment, and kidney dysfunction results in the accumulation of uremic toxins in the serum. The present study aimed to investigate whether indoxyl sulfate (IS), a representative uremic toxin, affects the pathophysiology of EOC. In this study, IS reduced the expression of Mas receptor (MasR) in cultured human EOC cells. Both knockdown of the aryl hydrocarbon receptor (AhR), which is an intracellular IS receptor, and inhibition of AhR function suppressed IS-mediated downregulation of MasR in SK-OV-3 cells. IS induced the phosphorylation of signal transducer and activator of transcription 3 (STAT3) in an AhR-dependent manner. Inhibition of the STAT3 pathway or reactive oxygen species production suppressed the IS-mediated reduction of MasR. IS stimulated cell migration and invasion of SK-OV-3 cells in an AhR-dependent manner. Cisplatin-nephropathy model mice exhibited elevated levels of serum IS accompanied by elevated levels of blood urea nitrogen and serum creatinine. Furthermore, intraperitoneal administration of IS in mice promoted tumor growth and metastasis. Finally, we found that the MasR agonist Ang-(1-7) suppressed the IS-mediated effects on cell proliferation, migration, and invasion of SK-OV-3 cells. However, the knockdown of MasR expression by specific small interfering RNA in the absence of IS resulted in only minimal promotion of cell migration and invasion. These findings demonstrate that IS promotes malignancy in ovarian cancer via AhR-mediated downregulation of MasR function, whereas Ang-(1-7) attenuates this effect, thereby suggesting that Ang-(1-7) could provide a future treatment strategy for this cancer type.

CDK4/6 inhibitor palbociclib promotes SARS-CoV-2 cell entry by down-regulating SKP2 dependent ACE2 degradation

Coronavirus disease 2019 (COVID-19) outbreak has become a global pandemic. CDK4/6 inhibitor palbociclib was reported to be one of the top-scored repurposed drugs to treat COVID-19. As the receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry, expression level of angiotensin-converting enzyme 2 (ACE2) is closely related to SARS-CoV-2 infection. In this study, we demonstrated that palbociclib and other methods could arrest cells in G0/G1 phase and up-regulate ACE2 mRNA and protein levels without altering its subcellular localization. Palbociclib inhibited ubiquitin-proteasome and lysosomal degradation of ACE2 through down-regulating S-phase kinase-associated protein 2 (SKP2). In addition, increased ACE2 expression induced by palbociclib and other cell cycle arresting compounds facilitated pseudotyped SARS-CoV-2 infection. This study suggested that ACE2 expression was down-regulated in proliferating cells. Cell cycle arresting compounds could increase ACE2 expression and facilitate SARS-CoV-2 cell entry, which may not be suitable therapeutic agents for the treatment of SARS-CoV-2 infection.

The alternative renin-angiotensin-system (RAS) signalling pathway in prostate cancer and its link to the current COVID-19 pandemic

BACKGROUND

The renin-angiotensin system is known to maintain blood pressure and body fluids. However, it has been found to consist of at least two major constituents, the classic and the alternative pathway, balancing and supporting each other's signalling in a very intricate way. Current research has shown that the renin-angiotensin system is involved in a broad range of biological processes and diseases, such as cancer and infectious diseases.

METHODS AND RESULTS

We conducted a literature review on the interaction of the renin-angiotensin system and prostate cancer and explored the research on the possible impact of the SARS-CoV-2 virus in this context. This review provides an update on contemporary knowledge into the alternative renin-angiotensin system, its role in cancer, specifically prostate cancer, and the implications of the current COVID-19 pandemic on cancer and cancer care.

CONCLUSION

In this work, we aim to demonstrate how shifting the RAS signalling pathway from the classic to the alternative axis seems to be a viable option in supporting treatment of specific cancers and at the same time demonstrating beneficial properties in supportive care. It however seems to be the case that the infection with SARS-CoV-2 and subsequent impairment of the renin-angiotensin-system could exhibit serious deleterious long-term effects even in oncology.

Chemotherapy induces ACE2 expression in breast cancer via the ROS-AKT-HIF-1α signaling pathway: a potential prognostic marker for breast cancer patients receiving chemotherapy

Background

Angiotensin-converting enzyme 2 (ACE2) is a key enzyme of the renin-angiotensin system and a well-known functional receptor for the entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) into host cells. The COVID-19 pandemic has brought ACE2 into the spotlight, and ACE2 expression in tumors and its relationship with SARS-COV-2 infection and prognosis of cancer patients have received extensive attention. However, the association between ACE2 expression and tumor therapy and prognosis, especially in breast cancer, remains ambiguous and requires further investigation. We have previously reported that ACE2 is elevated in drug-resistant breast cancer cells, but the exact function of ACE2 in drug resistance and progression of this malignant disease has not been explored.

Methods

The expression of ACE2 and HIF-1α in parental and drug-resistant breast cancer cells under normoxic and hypoxic conditions was analyzed by Western blot and qRT-PCR methods. The protein levels of ACE2 in plasma samples from breast cancer patients were examined by ELISA. The relationship between ACE2 expression and breast cancer treatment and prognosis was analyzed using clinical specimens and public databases. The reactive oxygen species (ROS) levels in breast cancer cells were measured by using a fluorescent probe. Small interfering RNAs (siRNAs) or lentivirus-mediated shRNA was used to silence ACE2 and HIF-1α expression in cellular models. The effect of ACE2 knockdown on drug resistance in breast cancer was determined by Cell Counting Kit 8 (CCK-8)-based assay, colony formation assay, apoptosis and EdU assay.

Results

ACE2 expression is relatively low in breast cancer cells, but increases rapidly and specifically after exposure to anticancer drugs, and remains high after resistance is acquired. Mechanistically, chemotherapeutic agents increase ACE2 expression in breast cancer cells by inducing intracellular ROS production, and increased ROS levels enhance AKT phosphorylation and subsequently increase HIF-1α expression, which in turn upregulates ACE2 expression. Although ACE2 levels in plasma and cancer tissues are lower in breast cancer patients compared with healthy controls, elevated ACE2 in patients after chemotherapy is a predictor of poor treatment response and an unfavorable prognostic factor for survival in breast cancer patients.

Conclusion

ACE2 is a gene in breast cancer cells that responds rapidly to chemotherapeutic agents through the ROS-AKT-HIF-1α axis. Elevated ACE2 modulates the sensitivity of breast cancer cells to anticancer drugs by optimizing the balance of intracellular ROS. Moreover, increased ACE2 is not only a predictor of poor response to chemotherapy, but is also associated with a worse prognosis in breast cancer patients. Thus, our findings provide novel insights into the spatiotemporal differences in the function of ACE2 in the initiation and progression of breast cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12967-022-03716-w.

Angiotensin-converting enzyme 2 identifies immuno-hot tumors suggesting angiotensin-(1-7) as a sensitizer for chemotherapy and immunotherapy in breast cancer

Background

Angiotensin-converting enzyme 2 (ACE2) is known as a tumor suppressor and lowly expressed in most cancers. The expression pattern and role of ACE2 in breast cancer (BC) have not been deeply elucidated.

Methods

A systematic pan-cancer analysis was conducted to assess the expression pattern and immunological role of ACE2 based on RNA-sequencing (RNA-seq) data downloaded from The Cancer Genome Atlas (TCGA). The correlation of ACE2 expression and immunological characteristics in the BC tumor microenvironment (TME) was evaluated. The role of ACE2 in predicting the response to therapeutic options was estimated. Moreover, the pharmacodynamic effect of angiotensin-(1–7) (Ang-1–7), the product of ACE2, on chemotherapy and immunotherapy was evaluated on the BALB/c mouse BC model. In addition, the plasma samples from BC patients receiving neoadjuvant chemotherapy were collected and subjected to the correlation analysis of the expression level of Ang-1–7 and the response to neoadjuvant chemotherapy.

Results

ACE2 was lowly expressed in BC tissues compared with that in adjacent tissues. Interestingly, ACE2 was shown the highest correlation with immunomodulators, tumor-infiltrating immune cells (TIICs), cancer immunity cycles, immune checkpoints, and tumor mutation burden (TMB) in BC. In addition, a high level of ACE2 indicated a low response to endocrine therapy and a high response to chemotherapy, anti-ERBB therapy, antiangiogenic therapy and immunotherapy. In the mouse model, Ang-1–7 sensitized mouse BC to the chemotherapy and anti-PD-1 immunotherapy, which revealed its significant anti-tumor effect. Moreover, a high plasma level of Ang-1–7 was associated with a better response to neoadjuvant chemotherapy.

Conclusions

ACE2 identifies immuno-hot tumors in BC, and its enzymatic product Ang-1–7 sensitizes BC to the chemotherapy and immunotherapy by remodeling the TME.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12575-022-00177-9.

Evaluation of 68Ga- and 177Lu-Labeled HZ20 Angiotensin-Converting Enzyme 2-Targeting Peptides for Tumor-Specific Imaging

Angiotensin-converting enzyme 2 (ACE2) is closely related to tumor formation. We developed the radiolabeled peptide pair ⁶⁸Ga/¹⁷⁷Lu-labeled 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-conjugated DX600 (⁶⁸Ga/¹⁷⁷Lu-HZ20), for the targeting and mapping of ACE2-overexpressing tumors. ⁶⁸Ga/¹⁷⁷Lu-HZ20 was prepared with a routine labeling method. HepG2^ACE2+/HepG2^WT cell lines were used to evaluate the specificity of ⁶⁸Ga/¹⁷⁷Lu-HZ20. Pharmacokinetics, biodistribution, and micro-PET/CT and -SPECT/CT imaging were performed, and radiation dosimetry was estimated. Immunohistochemistry (IHC) staining was performed to assess the expression of ACE2 in tumors. The radiolabeling yields of ⁶⁸Ga/¹⁷⁷Lu-HZ20 were 88.49 ± 8.57% (n > 10) and 84.71 ± 9.75% (n > 10), with specific activities of (18.74 ± 3.72) × 10⁶ and (17.85 ± 1.62) × 10⁶ GBq/mol, respectively. ⁶⁸Ga/¹⁷⁷Lu-HZ20 showed significant differences in the cellular uptake of HepG2^ACE2+/HepG2^WT cells and fast clearance in KM mice. Moreover, HepG2^ACE2+ tumors were clearly visualized in ⁶⁸Ga/¹⁷⁷Lu-HZ20 micro-PET/SPECT images. Based on micro-PET/CT, the standard uptake value (SUVmax) of HepG2^ACE2+ tumors was 0.66 ± 0.02 at 30 min postinjection, IHC confirmed the high expression of ACE2 in HepG2^ACE2+ tumors. In PET/CT images, the SUVmean of volunteer 1 was higher than the ¹⁸F-FDG value in the same lesion. ⁶⁸Ga/¹⁷⁷Lu-HZ20 was successfully obtained and showed high and specific uptake in tumors overexpressing ACE2. They may serve as paired probes for ACE2-targeting theranostics.

Small Activating RNA Modulation of the G Protein-Coupled Receptor for Cancer Treatment

G protein-coupled receptors (GPCRs) are the most common and important drug targets. However, >70% of GPCRs are undruggable or difficult to target using conventional chemical agonists/antagonists. Small nucleic acid molecules, which can sequence-specifically modulate any gene, offer a unique opportunity to effectively expand drug targets, especially those that are undruggable or difficult to address, such as GPCRs. Here, the authors report  for the first time that small activating RNAs (saRNAs) effectively modulate a GPCR for cancer treatment. Specifically, saRNAs promoting the expression of Mas receptor (MAS1), a GPCR that counteracts the classical angiotensin II pathway in cancer cell proliferation and migration, are identified. These saRNAs, delivered by an amphiphilic dendrimer vector, enhance MAS1 expression, counteracting the angiotensin II/angiotensin II Receptor Type 1 axis, and leading to significant suppression of tumorigenesis and the inhibition of tumor progression of multiple cancers in tumor-xenografted mouse models and patient-derived tumor models. This study provides not only a new strategy for cancer therapy by targeting the renin-angiotensin system, but also a new avenue to modulate GPCR signaling by RNA activation.

The Extracellular Matrix Environment of Clear Cell Renal Cell Carcinoma

Simple Summary

The extracellular matrix (ECM) controls fundamental properties of tumors, including growth, blood vessel investment, and invasion. The ECM defines rigidity of tumor tissue and individual ECM proteins have distinct biological effects on tumor cells. This article reviews the composition and biological functions of the ECM of clear cell renal cell carcinoma (ccRCC). The most frequent initiating genetic mutation in ccRCC inactivates the VHL gene, which plays a direct role in organizing the ECM. This is predicted to result in local ECM modification, which promotes the growth of tumor cells and the invasion of blood vessels. Later in tumor growth, connective tissue cells are recruited, which are predicted to produce large amounts of ECM, affecting the growth and invasive behaviors of tumor cells. Strategies to therapeutically control the ECM are under active investigation and a better understanding of the ccRCC ECM will determine the applicability of ECM-modifying drugs to this type of cancer.

Abstract

The extracellular matrix (ECM) of tumors is a complex mix of components characteristic of the tissue of origin. In the majority of clear cell renal cell carcinomas (ccRCCs), the tumor suppressor VHL is inactivated. VHL controls matrix organization and its loss promotes a loosely organized and angiogenic matrix, predicted to be an early step in tumor formation. During tumor evolution, cancer-associated fibroblasts (CAFs) accumulate, and they are predicted to produce abundant ECM. The ccRCC ECM composition qualitatively resembles that of the healthy kidney cortex in which the tumor arises, but there are important differences. One is the quantitative difference between a healthy cortex ECM and a tumor ECM; a tumor ECM contains a higher proportion of interstitial matrix components and a lower proportion of basement membrane components. Another is the breakdown of tissue compartments in the tumor with mixing of ECM components that are physically separated in healthy kidney cortex. Numerous studies reviewed in this work reveal effects of specific ECM components on the growth and invasive behaviors of ccRCCs, and extrapolation from other work suggests an important role for ECM in controlling ccRCC tumor rigidity, which is predicted to be a key determinant of invasive behavior.

Recent progress on vascular endothelial growth factor receptor inhibitors with dual targeting capabilities for tumor therapy

Vascular endothelial growth factor receptors (VEGFRs) are a family of receptor protein tyrosine kinases that play an important role in the regulation of tumor-induced angiogenesis. Currently, VEGFR inhibitors have been widely used in the treatment of various tumors. However, current VEGFR inhibitors are limited to a certain extent due to limited clinical efficacy and potential toxicity, which hinder their clinical application. Thus, the development of new strategies to improve the clinical outcomes and minimize the toxic effects of VEGFR inhibitors is required. Given the synergistic effect of VEGFR and other therapies in tumor development and progression, VEGFR dual-target inhibitors are becoming an attractive approach due to their favorable pharmacodynamics, low toxicity, and anti-resistant effects. This perspective provides an overview of the development of VEGFR dual-target inhibitors from multiple aspects, including rational target combinations, drug discovery strategies, structure–activity relationships and future directions.

Advances in Renal Cell Carcinoma Drug Resistance Models

Renal cell carcinoma (RCC) is the most common form of kidney cancer. Systemic therapy is the preferred method to eliminate residual cancer cells after surgery and prolong the survival of patients with inoperable RCC. A variety of molecular targeted and immunological therapies have been developed to improve the survival rate and prognosis of RCC patients based on their chemotherapy-resistant properties. However, owing to tumor heterogeneity and drug resistance, targeted and immunological therapies lack complete and durable anti-tumor responses; therefore, understanding the mechanisms of systemic therapy resistance and improving clinical curative effects in the treatment of RCC remain challenging. In vitro models with traditional RCC cell lines or primary cell culture, as well as in vivo models with cell or patient-derived xenografts, are used to explore the drug resistance mechanisms of RCC and screen new targeted therapeutic drugs. Here, we review the established methods and applications of in vivo and in vitro RCC drug resistance models, with the aim of improving our understanding of its resistance mechanisms, increasing the efficacy of combination medications, and providing a theoretical foundation for the development and application of new drugs, drug screening, and treatment guidelines for RCC patients.

Mechanistic Pathogenesis of Endothelial Dysfunction in Diabetic Nephropathy and Retinopathy

Diabetic nephropathy (DN) and diabetic retinopathy (DR) are microvascular complications of diabetes. Microvascular endothelial cells are thought to be the major targets of hyperglycemic injury. In diabetic microvasculature, the intracellular hyperglycemia causes damages to the vascular endothelium, via multiple pathophysiological process consist of inflammation, endothelial cell crosstalk with podocytes/pericytes and exosomes. In addition, DN and DR diseases development are involved in several critical regulators including the cell adhesion molecules (CAMs), the vascular endothelial growth factor (VEGF) family and the Notch signal. The present review attempts to gain a deeper understanding of the pathogenesis complexities underlying the endothelial dysfunction in diabetes diabetic and retinopathy, contributing to the development of new mechanistic therapeutic strategies against diabetes-induced microvascular endothelial dysfunction.

Functional deficiency of succinate dehydrogenase promotes tumorigenesis and development of clear cell renal cell carcinoma through weakening of ferroptosis

Clear cell renal cell carcinoma (ccRCC) is the most common subtype of renal carcinomas, with high mortality and poor prognoses worldwide. Succinate dehydrogenase (SDH) consists of four nuclear-encoded subunits and it is the only complex involved in both the tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS). Previous studies have shown decreased SDH activity in ccRCC. However, the role and underlying molecular mechanisms of SDH in ccRCC initiation and development remain unclear. In the present study, pan-cancer analysis of SDH gene expression was analyzed and the relationship between SDH gene expression and clinicopathological parameters was assessed using different databases. cBioPortal, UACLAN, and Tumor Immune Estimation Resource (TIMER) were subsequently utilized to analyze genetic alterations, methylation, and immune cell infiltration of SDH genes in ccRCC patients. We found SDHs were significantly downregulated in ccRCC tissues and correlated with ccRCC progression. Increased methylation and high SDH promoter mutation rates may be the cause of reduced expression of SDHs in ccRCC. Moreover, the interaction network showed that SDH genes were correlated with ferroptosis-related genes. We further demonstrated that SDH inhibition dampened oxidative phosphorylation, reduced ferroptotic events, and restored ferroptotic cell death, characterized by eliminated mitochondrial ROS levels, decreased cellular ROS and diminished peroxide accumulation. Collectively, this study provides new insights into the regulatory role of SDH in the carcinogenesis and progression of ccRCC, introducing a potential target for advanced antitumor therapy through ferroptosis.

Treatment with Angiotensin-(1-7) Prevents Development of Oral Papilloma Induced in K-ras Transgenic Mice

Oral Squamous Cell Carcinoma (OSCC) is the most common malignant cancer affecting the oral cavity. It is characterized by high morbidity and very few therapeutic options. Angiotensin (Ang)-(1-7) is a biologically active heptapeptide, generated predominantly from AngII (Ang-(1-8)) by the enzymatic activity of angiotensin-converting enzyme 2 (ACE 2). Previous studies have shown that Ang-(1-7) counterbalances AngII pro-tumorigenic actions in different pathophysiological settings, exhibiting antiproliferative and anti-angiogenic properties in cancer cells. However, the prevailing effects of Ang-(1-7) in the oral epithelium have not been established in vivo. Here, we used an inducible oral-specific mouse model, where the expression of a tamoxifen-inducible Cre recombinase (CreER^tam), which is under the control of the cytokeratin 14 promoter (K14-CreER^tam), induces the expression of the K-ras oncogenic variant KrasG12D (LSLK-ras^G12D). These mice develop highly proliferative squamous papilloma in the oral cavity and hyperplasia exclusively in oral mucosa within one month after tamoxifen treatment. Ang-(1-7) treated mice showed a reduced papilloma development accompanied by a significant reduction in cell proliferation and a decrease in pS6 positivity, the most downstream target of the PI3K/Akt/mTOR signaling route in oral papilloma. These results suggest that Ang-(1-7) may be a novel therapeutic target for OSCC.

The Extracellular Matrix Environment of Clear Cell Renal Cell Carcinoma Determines Cancer Associated Fibroblast Growth

Clear cell renal cell carcinoma (ccRCC) is the most common kidney cancer and is often caused by mutations in the oxygen-sensing machinery of kidney epithelial cells. Due to its pseudo-hypoxic state, ccRCC recruits extensive vasculature and other stromal components. Conventional cell culture methods provide poor representation of stromal cell types in primary cultures of ccRCC, and we hypothesized that mimicking the extracellular environment of the tumor would promote growth of both tumor and stromal cells. We employed proteomics to identify the components of ccRCC extracellular matrix (ECM) and found that in contrast to healthy kidney cortex, laminin, collagen IV, and entactin/nidogen are minor contributors. Instead, the ccRCC ECM is composed largely of collagen VI, fibronectin, and tenascin C. Analysis of single cell expression data indicates that cancer-associated fibroblasts are a major source of tumor ECM production. Tumor cells as well as stromal cells bind efficiently to a nine-component ECM blend characteristic of ccRCC. Primary patient-derived tumor cells bind the nine-component blend efficiently, allowing to us to establish mixed primary cultures of tumor cells and stromal cells. These miniature patient-specific replicas are conducive to microscopy and can be used to analyze interactions between cells in a model tumor microenvironment.

Platform Trials to Expedite Drug Development in Alzheimer's Disease: A Report from the EU/US CTAD Task Force

A diverse range of platforms has been established to increase the efficiency and speed of clinical trials for Alzheimer's disease (AD). These platforms enable parallel assessment of multiple therapeutics, treatment regimens, or participant groups; use uniform protocols and outcome measures; and may allow treatment arms to be added or dropped based on interim analyses of outcomes. The EU/US CTAD Task Force discussed the lessons learned from the Dominantly Inherited Alzheimer's Network Trials Unit (DIAN-TU) platform trial and the challenges addressed by other platform trials that have launched or are in the planning stages. The landscape of clinical trial platforms in the AD space includes those testing experimental therapies such as DIAN-TU, platforms designed to test multidomain interventions, and those designed to streamline trial recruitment by building trial-ready cohorts. The heterogeneity of the AD patient population, AD drugs, treatment regimens, and analytical methods complicates the design and execution of platform trials, yet Task Force members concluded that platform trials are essential to advance the search for effective AD treatments, including combination therapies.

ACE2 and Innate Immunity in the Regulation of SARS-CoV-2-Induced Acute Lung Injury: A Review

Despite the protracted battle against coronavirus acute respiratory infection (COVID-19) and the rapid evolution of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), no specific and effective drugs have to date been reported. Angiotensin-converting enzyme 2 (ACE2) is a zinc metalloproteinase and a critical modulator of the renin-angiotensin system (RAS). In addition, ACE2 has anti-inflammatory and antifibrosis functions. ACE has become widely known in the past decade as it has been identified as the primary receptor for SARS-CoV and SARS-CoV-2, being closely associated with their infection. SARS-CoV-2 primarily targets the lung, which induces a cytokine storm by infecting alveolar cells, resulting in tissue damage and eventually severe acute respiratory syndrome. In the lung, innate immunity acts as a critical line of defense against pathogens, including SARS-CoV-2. This review aims to summarize the regulation of ACE2, and lung host cells resist SARS-CoV-2 invasion by activating innate immunity response. Finally, we discuss ACE2 as a therapeutic target, providing reference and enlightenment for the clinical treatment of COVID-19.

Combining VEGF receptor inhibitors and angiotensin-(1-7) to target renal cell carcinoma

Resistance to tyrosine kinase inhibitors of the vascular endothelial growth factor receptor inevitably develops in most patients with metastatic kidney cancer. Our recent findings demonstrate that addition of angiotensin-(1-7) peptide can be a potential therapy that delays such resistance.