Urinary aquaporin 1 and perilipin 2: Can these novel markers accurately characterize small renal masses and help guide patient management?

Lipid droplets provide metabolic flexibility for cancer progression

A hallmark of cancer cells is their remarkable ability to efficiently adapt to favorable and hostile environments. Due to a unique metabolic flexibility, tumor cells can grow even in the absence of extracellular nutrients or in stressful scenarios. To achieve this, cancer cells need large amounts of lipids to build membranes, synthesize lipid-derived molecules, and generate metabolic energy in the absence of other nutrients. Tumor cells potentiate strategies to obtain lipids from other cells, metabolic pathways to synthesize new lipids, and mechanisms for efficient storage, mobilization, and utilization of these lipids. Lipid droplets (LDs) are the organelles that collect and supply lipids in eukaryotes and it is increasingly recognized that the accumulation of LDs is a new hallmark of cancer cells. Furthermore, an active role of LD proteins in processes underlying tumorigenesis has been proposed. Here, by focusing on three major classes of LD-resident proteins (perilipins, lipases, and acyl-CoA synthetases), we provide an overview of the contribution of LDs to cancer progression and discuss the role of LD proteins during the proliferation, invasion, metastasis, apoptosis, and stemness of cancer cells.

Lithographically defined encoded magnetic heterostructures for the targeted screening of kidney cancer

Renal cell carcinoma (RCC) is the 7th commonest cancer in the UK and the most lethal urological malignancy; 50% of all RCC patients will die from the condition. However, if identified early enough, small RCCs are usually cured by surgery or percutaneous procedures, with 95% 10 year survival. This study describes a newly developed non-invasive urine-based assay for the early detection of RCC. Our approach uses encoded magnetically controllable heterostructures as a substrate for immunoassays. These heterostructures have molecular recognition abilities and embedded patterned codes for a rapid identification of RCC biomarkers. The magnetic heterostructures developed for this study have a magnetic configuration designed for a remote multi axial control of their orientation by external magnetic fields, this control facilitates the code readout when the heterostructures are in liquid. Furthermore, the optical encoding of each set of heterostructures provides a multiplexed analyte capture platform, as different sets of heterostructures, specific to different biomarkers can be mixed together in a patient sample. Our results show a precise magnetic control of the heterostructures with an efficient code readout during liquid immunoassays. The use of functionalised magnetic heterostructures as a substrate for immunoassay is validated for urine specimen spiked with recombinant RCC biomarkers. Initial results of the newly proposed screening method on urine samples from RCC patients, and controls with no renal disorders are presented in this study. Comprehensive optimisation cycles are in progress to validate the robustness of this technology as a novel, non-invasive screening method for RCC.

Challenges in Pharmacological Intervention in Perilipins (PLINs) to Modulate Lipid Droplet Dynamics in Obesity and Cancer

Perilipins (PLINs) are the most abundant proteins in lipid droplets (LD). These LD-associated proteins are responsible for upgrading LD from inert lipid storage structures to fully functional organelles, fundamentally integrated in the lipid metabolism. There are five distinct perilipins (PLIN1-5), each with specific expression patterns and metabolic activation, but all capable of regulating the activity of lipases on LD. This plurality creates a complex orchestrated mechanism that is directly related to the healthy balance between lipogenesis and lipolysis. Given the essential role of PLINs in the modulation of the lipid metabolism, these proteins can become interesting targets for the treatment of lipid-associated diseases. Since reprogrammed lipid metabolism is a recognized cancer hallmark, and obesity is a known risk factor for cancer and other comorbidities, the modulation of PLINs could either improve existing treatments or create new opportunities for the treatment of these diseases. Even though PLINs have not been, so far, directly considered for pharmacological interventions, there are many established drugs that can modulate PLINs activity. Therefore, the aim of this study is to assess the involvement of PLINs in diseases related to lipid metabolism dysregulation and whether PLINs can be viewed as potential therapeutic targets for cancer and obesity.

Biomarkers for the Detection and Surveillance of Renal Cancer

Renal cell carcinoma (RCC) is a heterogeneous disease characterized by a broad spectrum of disorders in terms of genetics, molecular and clinical characteristics. There is an urgent need for noninvasive tools to stratify and select patients for treatment accurately. In this review, we analyze serum, urinary, and imaging biomarkers that have the potential to detect malignant tumors in patients with RCC. We discuss the characteristics of these numerous biomarkers and their ability to be used routinely in clinical practice. The development of biomarkers continues to evolve with promising prospects.

Early detection of kidney cancer using urinary proteins: a truly non-invasive strategy

OBJECTIVES

To review urinary protein biomarkers as potential non-invasive, easily obtainable, early diagnostic tools in renal cell carcinoma (RCC).

METHODS

A PubMed database search was performed up to the year 2020 to identify primary studies reporting potential urinary protein biomarkers for RCC. Separate searches were conducted to identify studies describing appropriate methods of developing cancer screening programmes and detection of cancer biomarkers.

RESULTS

Several urinary protein biomarkers are under validation for RCC diagnostics, e.g. aquaporin-1, perilipin-2, carbonic anhydrase-9, Raf-kinase inhibitory protein, nuclear matrix protein-22, 14-3-3 Protein β/α and neutrophil gelatinase-associated lipocalin. However, none has yet been validated or approved for clinical use due to low sensitivity or specificity, inconsistencies in appropriate study design, or lack of external validation.

CONCLUSIONS

Evaluation of biomarkers' feasibility, sample preparation and storage, biomarker validation, and the application of novel technologies may provide a solution that maximises the potential for a truly non-invasive biomarker in early RCC diagnostics.

Non-invasive urine markers for the differentiation between RCCs and oncocytoma

Background

Recently, our group showed that Vim3 is overexpressed in tissue samples of renal oncocytomas and Mxi‐2 in clear cell renal carcinoma (ccRCC). The mechanism leading to the truncation of both proteins is known and involves with two miRs, both detectable in urine. Since the analysis of miRs is time‐consuming, our aim was to identify the truncated proteins in urine instead. Furthermore, urine samples from small renal masses (SRMs) (n = 45, <4 cm) were analyzed to get a pre‐surgical differentiation of the cancer subtypes.

Methods

Urines were accessed from the urological biobank (n = 350). Proteins were isolated from urine samples, and Western blots were performed. Each sample was analyzed with ELISA for the expression of Vim3 and Mxi‐2. A lateral flow assay was established. For the detection of SRMs, the miRs were isolated and qRT‐PCR was performed.

Results

A significant increase of Vim3 in urines from patients with oncocytoma (n = 20) was detectable with ELISA compared to all other subtypes of RCCs (chromophobe (n = 50), papillary (n = 40), ccRCC (n = 200), and controls (n = 40) (***p < 0.0001)). Mxi‐2 was predominantly overexpressed in ccRCCs (***p < 0.0001). Lateral flow assay of Vim3 and Mxi‐2 shows two bands in the case of oncocytoma and ccRCC indicating the specificity of this test.

For SRMs, an overexpression of miR‐15a/Mxi2 was detectable in urine samples from ccRCC and chromoRCC patients. In contrast to that, miR‐498/Vim3 were predominantly overexpressed in oncocytoma patients.

Conclusion

Both proteins (Vim3 and Mxi‐2) were detectable in patients’ urines and can be used for the non‐invasive differentiation of kidney cancers.

Can we Avoid the Unnecessary Loss of nephrons in the Management of Small Solid Renal Masses? Additional Clinical Parameters to Predict Benign-malign Distinction

Objectives:

We aimed to investigate the predictive value of additional parameters for distinguishing benign-malign tumors and to prevent the loss of nephrons in small (≤4 cm) solid renal masses.

Methods:

The data of 56 patients underwent partial or radical nephrectomy between September 2009 and December 2017 due to diagnosis of localized renal cell carcinoma were retrospectively analyzed. Demographic datas, histopathological tumor types, neutrophil/lymphocyte ratio (NLR), monocyte/lymphocyte ratio (MLR), platelet/lymphocyte ratio (PLR), red blood cell distribution width (RDW), mean platelet volume (MPV), the Framingham risk score and its components, postoperative follow-up results were recorded. Patients were divided into two groups as benign and malign.

Results:

Among 56 patients with a median age of 60 (min: 35-max: 74) years, 13 patients had benign and 43 patients had malign pathologies. MLR (p=0.011), NLR (p=0.032), PLR (p=0.006), MPV (p=0.025), eGFR (p=0.019) and the Framingham score (p=0.008) were significantly higher in malign group. Among the components constituting the Framingham score, only presence of smoking (p=0.032), presence of hypertension (p=0.041) and total cholesterol values (p=0.021) were significantly higher. In multivariate analysis, NLR>2.02 (OR: 7.184, p=0.037), PLR>109.65 (OR: 12.692, p=0.002), MPV>3.44 (OR: 10.543, p=0.046) and Framingham score >10.5 (OR: 12.287, p=0.007) were found as predictive factors for distinguishing small solid renal masses concerning malignancy.

Conclusion:

We think that NLR, PLR, MPV and the Framingham scores may be used in the clinical evaluation of small solid renal masses. In this way, we may prevent the unnecessary loss of nephrons in benign masses with suspicion of malignancy.

Gene and immunohistochemical expression of HIF-1α, GLUT-1, FASN, and adipophilin in carcinoma ex pleomorphic adenoma development

OBJECTIVE

To analyze the gene and immunohistochemical expression of HIF-1α, GLUT-1, FASN, and adipophilin in normal salivary gland (NSG), pleomorphic adenoma (PA), and carcinoma ex pleomorphic adenoma (CXPA) samples.

MATERIAL AND METHODS

The gene expression was investigated by the real-time PCR (qRT-PCR) method in 9 samples of frozen tissues of normal salivary gland, 13 PA, and 10 CXPA. We validated the reactions by immunohistochemistry on 20 samples from NSG, 85 PA, and 44 CXPA.

RESULTS

Our results showed that there was no statistically significant difference in HIF-1α gene and immunohistochemistry expression among the tissues studied while FASN gene and immunohistochemistry expression increased along the carcinogenesis of the PA. GLUT-1 was significantly more expressed in tumor tissues (PA and CXPA), although protein is mainly expressed in transformed cells than in PA and NSG. In contrast, adipophilin was significantly more expressed in NSG while the expression of the protein increased in PA and CXPA.

CONCLUSIONS

In summary, the data presented here suggest that neoplastic cells reprogram the expression of GLUT-1 and adipophilin to adapt to the tumor microenvironment and reinforce, through immunohistochemical results, a possible transcriptional and post-translational regulatory mechanisms that act on the expression of these genes.

The genetic landscapes of urological cancers and their clinical implications in the era of high-throughput genome analysis

OBJECTIVE

With the advent of high-throughput genome analysis, we are increasingly able to sequence and hence understand the pathogenic processes underlying individual cancers. Recently, consortiums such as The Cancer Genome Atlas (TCGA) have performed large-scale projects to this end, providing significant amounts of information regarding the genetic landscapes of several cancers.

PATIENTS AND METHODS

We performed a narrative review of studies from the TCGA and other major studies. We aimed to summarise data exploring the clinical implications of specific genetic alterations, both prognostically and therapeutically, in four major urological cancers. These were renal cell carcinoma, muscle-invasive bladder cancer/carcinoma, prostate cancer, and testicular germ cell tumours.

RESULTS

With these four urological cancers, great strides have been made in the molecular characterisation of tumours. In particular, recent studies have focussed on identifying molecular subtypes of tumours with characteristic genetic alterations and differing prognoses. Other prognostic alterations have also recently been identified, including those pertaining to epigenetics and microRNAs. In regard to treatment, numerous options are emerging for patients with these cancers such as including immune checkpoint inhibition, epigenetic-based treatments, and agents targeting MAPK, PI3K, and DNA repair pathways. There are a multitude of trials underway investigating the effects of these novel agents, the results of which are eagerly awaited.

CONCLUSIONS

As medicine chases the era of personalised care, it is becoming increasingly important to provide individualised prognoses for patients. Understanding how specific genetic alterations affects prognosis is key for this. It will also be crucial to provide highly targeted treatments against the specific genetics of a patient's tumour. With work performed by the TCGA and other large consortiums, these aims are gradually being achieved. Our review provides a succinct overview of this exciting field that may underpin personalised medicine in urological oncology.

Aquaporins in Renal Diseases

Aquaporins (AQPs) are a family of highly selective transmembrane channels that mainly transport water across the cell and some facilitate low-molecular-weight solutes. Eight AQPs, including AQP1, AQP2, AQP3, AQP4, AQP5, AQP6, AQP7, and AQP11, are expressed in different segments and various cells in the kidney to maintain normal urine concentration function. AQP2 is critical in regulating urine concentrating ability. The expression and function of AQP2 are regulated by a series of transcriptional factors and post-transcriptional phosphorylation, ubiquitination, and glycosylation. Mutation or functional deficiency of AQP2 leads to severe nephrogenic diabetes insipidus. Studies with animal models show AQPs are related to acute kidney injury and various chronic kidney diseases, such as diabetic nephropathy, polycystic kidney disease, and renal cell carcinoma. Experimental data suggest ideal prospects for AQPs as biomarkers and therapeutic targets in clinic. This review article mainly focuses on recent advances in studying AQPs in renal diseases.