Parathyroid Hormone-Related Protein and Serum Calcium in Patients with Renal Cell Carcinoma

Clinicopathological and Preclinical Patient-Derived Model Studies Define High Expression of NRN1 as a Diagnostic and Therapeutic Target for Clear Cell Renal Cell Carcinoma

Background

Acquired therapeutic resistance and metastasis/recurrence remain significant challenge in advance renal cell carcinoma (RCC), thus the establishment of patient-derived cancer models may provide a clue to assess the problem. We recently characterized that neuritogenesis-related protein neuritin 1 (NRN1) functions as an oncogene in testicular germ cell tumor. This study aims to elucidate the role of NRN1 in RCC.

Methods

NRN1 expression in clinical RCC specimens was analyzed based on immunohistochemistry. NRN1-associated genes in RCC were screened by the RNA-sequencing dataset from The Cancer Genome Atlas (TCGA). RCC patient-derived cancer cell (RCC-PDC) spheroid cultures were established and their viabilities were evaluated under the condition of gene silencing/overexpression. The therapeutic effect of NRN1-specific siRNA was evaluated in RCC-PDC xenograft models.

Results

NRN1 immunoreactivity was positively associated with shorter overall survival in RCC patients. In TCGA RCC RNA-sequencing dataset, C-X-C chemokine receptor type 4 (CXCR4), a prognostic and stemness-related factor in RCC, is a gene whose expression is substantially correlated with NRN1 expression. Gain- and loss-of-function studies in RCC-PDC spheroid cultures revealed that NRN1 significantly promotes cell viability along with the upregulation of CXCR4. The NRN1-specific siRNA injection significantly suppressed the proliferation of RCC-PDC-derived xenograft tumors, in which CXCR4 expression is significantly repressed.

Conclusion

NRN1 can be a potential diagnostic and therapeutic target in RCC as analyzed by preclinical patient-derived cancer models and clinicopathological studies.

Functional inhibition of cancer stemness-related protein DPP4 rescues tyrosine kinase inhibitor resistance in renal cell carcinoma

Tyrosine kinase inhibitors (TKIs) are used as targeted drugs for advanced renal cell carcinoma (RCC), although most cases eventually progress by acquiring resistance. Cancer stemness plays critical roles in tumor aggressiveness and therapeutic resistance, and dipeptidyl peptidase IV (DPP4) has been recently identified as a cancer stemness-related protein. A question arises whether DPP4 contributes to TKI efficacy in RCC. We established patient-derived RCC spheroids and showed that DPP4 expression is associated with stemness-related gene expression. TKI sunitinib resistance was rescued by DPP4 inhibition using sitagliptin or specific siRNAs in RCC cells and tumors. DPP4 expression can be inducible by retinoic acid and repressed by ALDH1A inhibition. Among type 2 diabetes patients with clinical RCC tumors, higher TKI efficacy is observed in those bearing DPP4^high tumors treated with DPP4 inhibitors. This study provides new insights into TKI resistance and drug repositioning of DPP4 inhibitor as a promising strategy for advanced RCC.

Serum Calcium Levels Before Antitumour Therapy Predict Clinical Outcomes in Patients with Nasopharyngeal Carcinoma

PURPOSE

The prognostic value of serum calcium levels in nasopharyngeal carcinoma (NPC) remains unknown. This study aimed to evaluate the prognostic value of serum calcium levels in patients with NPC.

PATIENTS AND METHODS

A total of 2094 patients diagnosed with NPC between April 2009 and September 2012 were enrolled in this retrospective analysis. The median follow-up time was 96.3 months (range: 4.1-120.0 months). Univariate and multivariable Cox proportional hazards models were used to identify significant and independent prognostic predictors of overall survival (OS), disease-free survival (DFS), distant metastasis-free survival (DMFS), and relapse-free survival (RFS).

RESULTS

Overall, low serum calcium levels were detected in 1109/2094 (53.00%) patients and tended to be more frequently detected in older (P<0.001) and female (P=0.001) patients. Patients with low serum calcium levels had poorer OS (P=0.011), DFS (P=0.012) and DMFS (P=0.004) than those with high serum calcium levels, but serum calcium levels had no significant effect on RFS (P=0.376). In univariate and multivariable analyses, low serum calcium levels were a statistically significant and independent prognostic factor for OS, DFS, and DMFS but had no prognostic value for RFS.

CONCLUSION

Serum calcium levels can serve as a prognostic predictor and guide more individualized treatment for NPC patients.

DYSF expression in clear cell renal cell carcinoma: A retrospective study of 2 independent cohorts

OBJECTIVE

Renal cell carcinoma (RCC) is the most typical type of kidney cancer in adults. Hypercalcemia is a well known paraneoplastic syndrome associated with RCC and recent studies have reported that hypercalcemia is closely related to the poor prognosis of RCC patients. Clear cell RCC (ccRCC) is the most common and aggressive subtype of RCC. Although the histological classification of RCC is important for determination of appropriate treatment strategies, effective biomarkers for predicting prognosis of ccRCC have not yet been identified. Since calcium levels affect the prognosis of RCC patients, we evaluated whether the calcium-sensing genes on the plasma membrane, including those encoding calcium channels, CaSR, GPRC6a, and DYSF, could be used as biomarkers to predict the prognosis of ccRCC patients.

METHODS

Information from 537 patients from The Cancer Genome Atlas (TCGA; n = 446) and International Cancer Genome Consortium (ICGC; n = 91) was used in this study. Among these genes, DYSF was the only gene whose expression correlated with overall survival of both TGCA and ICGC patients.

RESULTS

Although DYSF gene expression was higher in ccRCC tissue than in normal kidney tissue, Kaplan-Meier curves showed that the survival rate of ccRCC patients with high DYSF expression was significantly higher than that of patients with low DYSF expression (TCGA, P < 0.0001; ICGC, P = 0.0011). We also validated the potential of DYSF as a prognostic biomarker for ccRCC by conducting a time-dependent area under the curve (AUC) analysis and 5-years receiver operating characteristic curve analysis. Finally, multivariate regression analysis revealed that the expression of DYSF is independent of other prognostic parameters (TCGA, P = 0.017; ICGC, P = 0.006).

CONCLUSIONS

These results suggested that DYSF may play a suppressive role in the progression of ccRCC and could act as a promising prognostic biomarker for predicting the survival of ccRCC patients.

Methods for the evaluation of biomarkers in patients with kidney and liver diseases: multicentre research programme including ELUCIDATE RCT

Background

Protein biomarkers with associations with the activity and outcomes of diseases are being identified by modern proteomic technologies. They may be simple, accessible, cheap and safe tests that can inform diagnosis, prognosis, treatment selection, monitoring of disease activity and therapy and may substitute for complex, invasive and expensive tests. However, their potential is not yet being realised.

Design and methods

The study consisted of three workstreams to create a framework for research: workstream 1, methodology – to define current practice and explore methodology innovations for biomarkers for monitoring disease; workstream 2, clinical translation – to create a framework of research practice, high-quality samples and related clinical data to evaluate the validity and clinical utility of protein biomarkers; and workstream 3, the ELF to Uncover Cirrhosis as an Indication for Diagnosis and Action for Treatable Event (ELUCIDATE) randomised controlled trial (RCT) – an exemplar RCT of an established test, the ADVIA Centaur® Enhanced Liver Fibrosis (ELF) test (Siemens Healthcare Diagnostics Ltd, Camberley, UK) [consisting of a panel of three markers – (1) serum hyaluronic acid, (2) amino-terminal propeptide of type III procollagen and (3) tissue inhibitor of metalloproteinase 1], for liver cirrhosis to determine its impact on diagnostic timing and the management of cirrhosis and the process of care and improving outcomes.

Results

The methodology workstream evaluated the quality of recommendations for using prostate-specific antigen to monitor patients, systematically reviewed RCTs of monitoring strategies and reviewed the monitoring biomarker literature and how monitoring can have an impact on outcomes. Simulation studies were conducted to evaluate monitoring and improve the merits of health care. The monitoring biomarker literature is modest and robust conclusions are infrequent. We recommend improvements in research practice. Patients strongly endorsed the need for robust and conclusive research in this area. The clinical translation workstream focused on analytical and clinical validity. Cohorts were established for renal cell carcinoma (RCC) and renal transplantation (RT), with samples and patient data from multiple centres, as a rapid-access resource to evaluate the validity of biomarkers. Candidate biomarkers for RCC and RT were identified from the literature and their quality was evaluated and selected biomarkers were prioritised. The duration of follow-up was a limitation but biomarkers were identified that may be taken forward for clinical utility. In the third workstream, the ELUCIDATE trial registered 1303 patients and randomised 878 patients out of a target of 1000. The trial started late and recruited slowly initially but ultimately recruited with good statistical power to answer the key questions. ELF monitoring altered the patient process of care and may show benefits from the early introduction of interventions with further follow-up. The ELUCIDATE trial was an ‘exemplar’ trial that has demonstrated the challenges of evaluating biomarker strategies in ‘end-to-end’ RCTs and will inform future study designs.

Conclusions

The limitations in the programme were principally that, during the collection and curation of the cohorts of patients with RCC and RT, the pace of discovery of new biomarkers in commercial and non-commercial research was slower than anticipated and so conclusive evaluations using the cohorts are few; however, access to the cohorts will be sustained for future new biomarkers. The ELUCIDATE trial was slow to start and recruit to, with a late surge of recruitment, and so final conclusions about the impact of the ELF test on long-term outcomes await further follow-up. The findings from the three workstreams were used to synthesise a strategy and framework for future biomarker evaluations incorporating innovations in study design, health economics and health informatics.

Trial registration

Current Controlled Trials ISRCTN74815110, UKCRN ID 9954 and UKCRN ID 11930.

Funding

This project was funded by the NIHR Programme Grants for Applied Research programme and will be published in full inProgramme Grants for Applied Research; Vol. 6, No. 3. See the NIHR Journals Library website for further project information.

Prognosis of metastatic renal cell carcinoma with first-line interferon-α therapy in the era of molecular-targeted therapy

The RCC‐SELECT study showed the correlation between single nucleotide polymorphisms (SNP) in STAT3 gene and survival in metastatic renal cell carcinoma (mRCC) patients with first‐line interferon‐α (IFN‐α). In that study, even patients with STAT3 SNP linked to shorter overall survival (OS) exhibited remarkably improved prognosis. All 180 patients evaluated in the above study were further analyzed for correlation between OS and demographics/clinicopathological parameters. OS was estimated using the Kaplan–Meier method. Associations between OS and potential prognostic factors were assessed using the log‐rank test and the Cox proportional hazards model. The median OS was 42.8 months. Univariate analysis showed that worse Eastern Cooperative Oncology Group‐performance status (ECOG‐PS), high T stage, regional lymph node metastasis, distant metastasis, higher grade, infiltrative growth pattern, the presence of microscopic vascular invasion (MVI), hypercalcemia, anemia, thrombocytopenia and elevated C‐reactive protein were significantly associated with OS. Multivariate analysis revealed that ECOG‐PS (hazard ratio [HR] = 3.665, P = 0.0004), hypercalcemia (HR = 6.428, P = 0.0005) and the presence of MVI (HR = 2.668, P = 0.0109) were jointly significant poor prognostic factors. This is the first study analysing prognostic factors of mRCC patients with first‐line IFN‐α using large cohort of the prospective study. The present study suggests that first‐line IFN‐α is still a useful therapy for mRCC even in the era of molecular targeted therapy.

Tumor signatures of PTHLH overexpression, high serum calcium, and poor prognosis were observed exclusively in clear cell but not non clear cell renal carcinomas

High serum calcium (Ca) due to aberrant secretion of tumor parathyroid hormone-like hormone (PTHLH) is a well-known paraneoplastic sign and is associated with poor prognosis in patients with renal cell carcinoma (RCC). However, the status of serum Ca and tumor PTHLH expression have not been verified using the 2004 World Health Organization (WHO) renal tumor classification. We retrospectively reviewed corrected serum Ca levels at initial onset (n = 683) and/or as of recurrence (n = 71) in patients with RCC. We also examined a total of 623 renal parenchymal tumor samples for PTHLH mRNA expressions by quantitative real-time PCR. High serum Ca concomitant with PTHLH overexpression in tumors was observed exclusively in clear cell RCC but not in other non clear cell subtype tumors, including papillary, chromophobe, collecting-duct, unclassified, and other rare subtype RCCs or in benign oncocytomas and angiomyolipomas. In clear cell RCC, PTHLH expression was significantly high in male patients, and was associated with a symptomatic presentation, higher grade, and higher stage cases, whereas it was not associated with VHL gene status. Univariate analyses demonstrated that high PTHLH expression was strongly associated with poor outcome both in overall survival (OS) and disease-free survival (DFS) for patients who underwent standard nephrectomy. Further multivariate Cox analyses revealed that the PTHLH expressions remained as independent prognostic parameters for OS but not for DFS. These data suggest that the previously characterized tumor signatures of high serum Ca due to high PTHLH expression and poor prognosis are clear cell RCC-specific features, whereas these characteristics are rare in non clear cell RCCs.

Hypercalcemia of malignancy associated with renal cell carcinoma in a dog

A 10 yr old castrated male Siberian husky was evaluated for polyuria, polydipsia, a retroperitoneal mass, and urolithiasis. A marked elevation in Ca was noted on initial blood work, and results of additional testing were consistent with hypercalcemia of malignancy, including an elevated parathyroid hormone-related peptide (PTHrp) value. Based on clinical signs, blood work, diagnostic imaging, and cytology results, unilateral renal neoplasia was suspected. Following a complete right nephrectomy and cystotomy, histopathologic examination confirmed a diagnosis of renal cell carcinoma (RCC). Five days postoperatively, the hypercalcemia had nearly resolved and the PTHrp was zero. This is the first reported case of hypercalcemia of malignancy associated with RCC in a dog.

Osteopontin but not parathyroid hormone-related protein predicts prognosis in human renal cell carcinoma

OBJECTIVE

To evaluate the relationship between osteopontin (OPN) in serum and plasma and parathyroid hormone-related protein (PTHrP) in serum, plasma and tumour tissue, and to assess the prognostic impact of OPN and PTHrP in human renal cell carcinoma (RCC).

MATERIAL AND METHODS

The study included 269 patients with RCC. In 189 patients, immunohistochemical (IHC) PTHrP tumour tissue expression was evaluated, and OPN and PTHrP in serum were assessed. In 80 patients, plasma OPN and PTHrP were analysed. Tumour type, TNM stage, nuclear grade and RCC-specific survival were also registered. In a sub-group, IHC expression of CD 31 was assessed. The prognostic information of the factors was analysed using uni- and multivariate analyses.

RESULTS

The median OPN level was 2.3 times higher in plasma than in serum. Serum OPN was significantly higher in patients with papillary RCC compared to clear cell RCC and chromophobe RCC. Both serum and plasma OPN levels were positively correlated to TNM stage and nuclear grade. Multivariate analysis showed that serum and plasma OPN levels were independent prognostic factors for RCC-specific survival, along with TNM stage. Immunohistochemical expression of PTHrP associated to TNM stage but not to nuclear grade or serum OPN. Furthermore, IHC expression of PTHrP was positively correlated to serum PTHrP but inversely to tumour CD31 expression. Plasma PTHrP was increased in 20% of the patients and related to TNM stage but not to nuclear grade. Plasma OPN was significantly higher in patients with increased PTHrP levels, compared to those with normal levels.

CONCLUSION

Plasma OPN levels differed between RCC types, and in clear cell RCC, both serum and plasma OPN levels were independent predictors of survival. We found no evidence for prognostic value related to circulating levels or the IHC expression of PTHrP.

Mechanisms and treatment of hypercalcemia of malignancy

PURPOSE OF REVIEW

Hypercalcemia of malignancy is a common paraneoplastic syndrome and a frequent complication of advanced breast and lung cancer, and multiple myeloma. The development of this malignancy complication often purports a poor prognosis. Thorough evaluation to establish the cause of hypercalcemia is essential because some patients may actually have undiagnosed primary hyperparathyroidism.

RECENT FINDINGS

Production of humoral factors by the primary tumor, collectively known as humoral hypercalcemia of malignancy (HHM), is the mechanism responsible for 80% of cases. The vast majority of HHM is caused by tumor-produced parathyroid hormone-related protein followed by infrequent tumor production of 1,25-dihydroxyvitamin D and parathyroid hormone. The remaining 20% of cases are caused by bone metastasis with consequent bone osteolysis and release of skeletal calcium. Key therapies are saline hydration to promote calciuresis and bisphosphonates to reduce pathologic osteoclastic bone resorption. Calcitonin and glucocorticoids, especially in 1,25-dihydroxyvitamin D-mediated HHM, also have calcium-lowering effects.

SUMMARY

Recent discoveries on mechanisms of malignancy-associated hypercalcemia highlight the critical role of the osteoclast. Bisphosphonates and other novel therapies being evaluated in clinical trial target this bone-resorbing cell type and provide effective and durable serum calcium reduction.

Putative biomarker genes for grading clear cell renal cell carcinoma

OBJECTIVE

The initial objective of this renal cancer study was to identify gene sets in clear cell renal cell carcinoma (ccRCC) to support grading of ccRCC histopathology.

MATERIALS AND METHODS

Preselected ccRCC tumor tissues of grade 1 (G1, n = 14) and grade 3 (G3, n = 15) as well es 14 normal kidney tissues thereof were subjected to microarray expression analysis using Human Genome U133 Plus 2.0 Array. Event ratio scoring, hierarchical clustering and principal component analysis were used to determine gene sets that distinguish expression profiles from normal kidney tissue, G1 and G3 tumor tissues.

RESULTS

An initial set of 73 genes provided seven gene subclusters (SC01 to SC07) that distinguish RNA expression profiles from G1, G3 tumor and normal kidney tissues. A ranked list of 24 genes was determined that separated G1 from G3 tumors in high concordance with histopathological grading confirmed by immunohistochemical analysis of ceruloplasmin protein expression.

CONCLUSION

A final set of 24 genes has been determined awaiting further validation on the RNA as well as on the protein level by studying an additional cohort of ccRCC patients. A reliable separation of G1 and G3 tumor grades will be instrumental to foster and direct the administration of upcoming targeted therapeutics of ccRCC tumors in a more predictive and reliable manner.

Hypercalcemia of malignancy with simultaneous elevation in serum parathyroid hormone--related peptide and 1,25-dihydroxyvitamin D in a patient with metastatic renal cell carcinoma

OBJECTIVE

To determine the cause of refractory hypercalcemia in a patient with metastatic renal cell carcinoma.

METHODS

We describe the clinical, pathologic, and immunostain findings in a patient with metastatic renal cell carcinoma and hypercalcemia of malignancy refractory to intravenous bisphosphonates.

RESULTS

A 57-year-old man with a remote history of clear cell renal cell carcinoma was referred to our clinic for evaluation of resistant hypercalcemia 12 years after nephrectomy. The patient had simultaneous elevation of serum 1,25-dihydroxyvitamin D and parathyroid hormone-related peptide. Computed tomographic scan of the chest and abdomen demonstrated numerous ring-enhancing lesions in the liver, and histologic examination of a biopsy specimen revealed liver tissue infiltrated by a malignant neoplasm composed of cells with clear and eosinophilic cytoplasm, arranged in tubules and nests. Findings were morphologically consistent with renal cell carcinoma of clear cell type, and positive immunostaining with the epithelial markers EMA and CAM 5.2 were supportive of the morphologic impression of renal cell carcinoma. The tumor showed expression of 25-hydroxyvitamin D 1alpha-hydroxylase by immunostaining. After failing to respond to intravenous bisphosphonates, the hypercalcemia improved with prednisone treatment.

CONCLUSIONS

In some patients with renal cell carcinoma, hypercalcemia of malignancy is associated with simultaneous elevation in serum 1,25-dihydroxyvitamin D and parathyroid hormone-related peptide. As our case exemplifies, it is imperative to identify such patients because hypercalcemia due to elevated 1,25-dihydroxyvitamin D levels may respond better to glucocorticoid treatment than to the conventional bisphosphonate therapy.

Renal cell carcinoma presenting with paraneoplastic hypercalcemic coma: a case report and review of the literature

We report a case of a 62-year-old woman with renal cell carcinoma (RCC) presenting with a hypercalcemia-induced coma. A laboratory evaluation indicated nonparathyroid-mediated hypercalcemia with an initial serum calcium level of 18.6 mg/dL. Our patient's parathyroid hormone (PTH)-related peptide level was undetectable. Initial imaging was negative, but PET scan identified a mass in the upper pole of the left kidney. Our patient underwent partial nephrectomy, and the mass was identified as RCC on final pathology. After surgery, her hypercalcemia resolved and PTH returned to normal limits. This case report describes a patient with RCC with the unusual presentation of hypercalcemic coma. We review the differential diagnosis of malignant hypercalcemia and the evaluation of hypercalcemia occurring with RCC. This case illustrates the need to carefully review and interpret all available data, especially when conventional testing in the work-up of hypercalcemia is unrevealing.

Skeletal metastasis: Established and emerging roles of parathyroid hormone related protein (PTHrP)

Parathyroid hormone related protein (PTHrP) is a well characterized tumor derived product that also has integral functions in normal development and homeostasis. PTHrP is produced by virtually all tumor types that metastasize to bone and numerous studies have demonstrated a correlation between PTHrP expression and skeletal localization of tumors. PTHrP has prominent effects in bone via its interaction with the PTH-1 receptor on osteoblastic cells. Through indirect means, PTHrP supports osteoclastogenesis by upregulating the receptor activator of NFkappaB ligand (RANKL) in osteoblasts. PTHrP also regulates osteoblast proliferation and differentiation in manners that are temporal and dose dependent. Bone turnover has been implicated in the localization of tumors to bone and PTHrP increases bone turnover. Bone turnover results in the release of growth factors such as TGFbeta and minerals such as calcium, both of which impact tumor cell growth and contribute to continued PTHrP production. PTHrP also has anabolic properties and could be in part responsible for osteoblastic type reactions in prostate cancer. Finally, emerging roles of PTH and PTHrP in the support of hematopoietic stem cell development in the bone marrow microenvironment suggest that an interaction between hematopoietic cells and tumor cells warrants further investigation.

Parathyroid hormone-related protein in human renal cell carcinoma

Parathyroid hormone-related protein (PTHrP), a polyprotein discovered in 1987, plays crucial roles not only in development and in various physiological events associated with normal life, but also in a number of pathological conditions such as cancer. PTHrP appears as the major causative agent in humoral hypercalcemia of malignancy (HHM) associated to a broad range of tumors. However, this is only one aspect of the multiple facets of PTHrP in cancer biology. Indeed, the complex growth factor-like properties of PTHrP has shed new light onto potential roles of this peptide in the regulation of tumor growth and invasion. Initial studies in breast, prostate and lung cancer and recent results in renal cell carcinoma (RCC) suggest such roles and highlight the therapeutic potential of PTHrP-targeting strategies in human cancer including RCC. In this review, the role of PTHrP in RCC tumorigenesis and its potential as a therapeutic target will be discussed.