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

Hypercalcemia and Renal Mass: A Diagnostically Challenging Case

Hypercalcemia of malignancy frequently occurs in patients with solid tumors as a paraneoplastic syndrome known as humoral hypercalcemia of malignancy (HHM), caused by the secretion of parathyroid hormone-related peptide (PTHrP). On the other hand, 1,25-dihydroxyvitamin D [1,25(OH)2D]-mediated hypercalcemia is a less common cause of hypercalcemia of malignancy and is mostly observed in lymphoma patients. Here, we report an interesting case of a 77-year-old male nursing home resident with suspected renal cell carcinoma (RCC) presenting with severe hypercalcemia (18.7 mg/dL), which was initially presumed to be HHM. However, workup revealed nonsuppressed parathyroid hormone, low PTHrP, and elevated 25-hydroxyvitamin D and 1,25(OH)2D levels. Steroids were initiated due to an inadequate response to bisphosphonate therapy and elevated vitamin D metabolites, resulting in further reduction in serum calcium levels. This case highlights the need to consider multiple concurrent etiologies in the differential diagnosis of severe hypercalcemia, including the possible role of calcitriol-mediated hypercalcemia in RCC.

Prognostic impact of paraneoplastic syndromes on patients with non-metastatic renal cell carcinoma undergoing surgery: Results from Canadian Kidney Cancer information system

INTRODUCTION

The impact of paraneoplastic syndromes (PNS) on survival in patients with renal cell carcinoma (RCC) is uncertain. This study was conducted to analyze the association of PNS with recurrence and survival of patients with non-metastatic RCC undergoing nephrectomy.

METHODS

The Canadian Kidney Cancer information system is a multi-institutional cohort of patients started in January 2011. Patients with nephrectomy for non-metastatic RCC were identified. PNS included anemia, polycythemia, hypercalcemia, and weight loss. Associations between PNS and recurrence or death were assessed using Kaplan-Meier curves and multivariable analysis.

RESULTS

Of 4337 patients, 1314 (30.3%) had evidence of one or more PNS. Patients with PNS were older, had higher comorbidity, and had more advanced clinical and pathological tumor characteristics as compared to patients without PNS (all p<0.05). Kaplan-Meier five-year estimated recurrence-free survival (RFS), cancer-specific survival (CSS), and overall survival (OS) were significantly worse in patients with PNS (63.7%, 84.3%, and 79.6%, respectively, for patients with PNS vs. 73.9%, 90.8%, and 90.1%, respectively, for patients without PNS, all p<0.005). On univariable analysis, presence of PNS increased risk of recurrence (hazard ratio [HR] 1.67, 95% confidence interval [CI] 1.48-1.90, p<0.0001) and cancer-related death (HR 1.85, 95% CI 1.34-2.54, p=0.0002). Adjusting for known prognostic factors, PNS was not associated with recurrence or survival.

CONCLUSIONS

In non-metastatic RCC patients undergoing surgery, presence of PNS is associated with older age, higher Charlson comorbidity index score, advanced tumor stage, and aggressive tumor histology. Following surgery, baseline PNS is not strongly independently associated with recurrence or death.

WNK1 promotes renal tumor progression by activating TRPC6-NFAT pathway

Deregulation of Ca²⁺ signaling has been regarded as one of the key features of cancer progression. Lysine-deficient protein kinase 1 (WNK1), a major regulator of renal ion transport, regulates Ca²⁺ signaling through stimulating the phosphatidylinositol 4-kinase IIIα (PI4KIIIα) to activate Gαq-coupled receptor/PLC-β signaling. However, the contribution of WNK1-mediated Ca²⁺ signaling in the development of clear-cell renal-cell carcinoma (ccRCC) is yet unknown. We found that the canonical transient receptor potential channel (TRPC)6 was widely expressed in ccRCC tissues and functioned as a primary Ca²⁺ influx mechanism. We further identified that the expressions of WNK1, PI4KIIIα, TRPC6, and the nuclear factor of activated T cells cytoplasmic 1 (NFATc1) were elevated in the tumor tissues compared with the adjacent normal tissues. WNK1 expression was directly associated with the nuclear grade of ccRCC tissues. Functional experiments showed that WNK1 activated TRPC6-mediated Ca²⁺ influx and current by stimulating PI4KIIIα. Notably, the inhibition of WNK1-mediated TRPC6 activation and its downstream substrate calcineurin attenuated NFATc1 activation and the subsequent migration and proliferation of ccRCC. These findings revealed a novel perspective of WNK1 signaling in targeting the TRPC6-NFATc1 pathway as a therapeutic potential for renal-cell carcinoma.-Kim, J.-H., Hwang, K.-H., Eom, M., Kim, M., Park, E. Y., Jeong, Y., Park, K.-S., Cha, S.-K. WNK1 promotes renal tumor progression by activating TRPC6-NFAT pathway.

Animal Models of Cancer-Associated Hypercalcemia

Cancer-associated hypercalcemia (CAH) is a frequently-occurring paraneoplastic syndrome that contributes to substantial patient morbidity and occurs in both humans and animals. Patients with CAH are often characterized by markedly elevated serum calcium concentrations that result in a range of clinical symptoms involving the nervous, gastrointestinal and urinary systems. CAH is caused by two principle mechanisms; humorally-mediated and/or through local osteolytic bone metastasis resulting in excessive calcium release from resorbed bone. Humoral hypercalcemia of malignancy (HHM) is the most common mechanism and is due to the production and release of tumor-associated cytokines and humoral factors, such as parathyroid hormone-related protein (PTHrP), that act at distant sites to increase serum calcium concentrations. Local osteolytic hypercalcemia (LOH) occurs when primary or metastatic bone tumors act locally by releasing factors that stimulate osteoclast activity and bone resorption. LOH is a less frequent cause of CAH and in some cases can induce hypercalcemia in concert with HHM. Rarely, ectopic production of parathyroid hormone has been described. PTHrP-mediated hypercalcemia is the most common mechanism of CAH in human and canine malignancies and is recognized in other domestic species. Spontaneous and experimentally-induced animal models have been developed to study the mechanisms of CAH. These models have been essential for the evaluation of novel approaches and adjuvant therapies to manage CAH. This review will highlight the comparative aspects of CAH in humans and animals with a discussion of the available animal models used to study the pathogenesis of this important clinical syndrome.

Is severe hypercalcemia immediately life-threatening?

OBJECTIVE

Severe hypercalcemia is often considered an emergency because of a potential risk of cardiac arrest or coma. However, there is little evidence to support this. The aim of our study was to assess whether severe hypercalcemia (Ca>4 mmol/l or 16 mg/dl) was associated with immediately life-threatening cardiac arrhythmias or neurological complications in patients admitted to the Emergency Department (ED).

METHODS

A retrospective observational study was carried out over a 5-year period (2008-2012). Eligible patients were admitted to the Adult Emergency Department of Nantes University Hospital and had a calcium concentration in excess of 4 mmol/l. There were no exclusion criteria. The primary outcome was the number of life-threatening cardiac arrhythmias and/or neurological complications during the stay in the ED. The secondary outcomes were correlation between calcium concentrations/ECG QTc intervals and mortality.

RESULTS

A total of 126 204 adult patients had calcium concentrations measured. Thirty one (0.025%) patients had severe hypercalcemia as defined in our study. The median calcium concentration was 4.3 mmol/l (Q1, 4.2; Q3, 4.7) and the median albumin-adjusted calcium concentration was 4.3 mmol/l (Q1, 4.1; Q3, 4.7). No patient presented with a life-threatening cardiac event during stay in the ED. The median ED stay was 7 h 32 min. One patient presented with a coma of multifactorial origin. There was no correlation between calcemia and QTc intervals (P=0.60). Mortality at 1 year was 55% (17 patients).

CONCLUSION

We found no cases of immediately life-threatening cardiac arrhythmias or neurological complications associated with hypercalcemia above 4 mmol/l over a 5-year period in a large tertiary ED.

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.

Paraneoplastic syndromes are associated with adverse prognosis among patients with renal cell carcinoma undergoing nephrectomy

OBJECTIVES

To analyze the association of paraneoplastic syndromes (PNS) with progression-free (PFS) and cancer-specific survival (CSS) among patients with renal cell carcinoma (RCC) undergoing nephrectomy.

METHODS

We performed a retrospective analysis of 2865 patients undergoing nephrectomy for localized RCC at Mayo Clinic from 1990 to 2010. PNS analyzed were anemia, polycythemia, hypercalcemia, recent-onset hypertension, and liver dysfunction. PFS and CSS were estimated using Kaplan-Meier method and compared with Cox proportional hazard models, unadjusted and adjusted for clinicopathologic features.

RESULTS

A total of 661 (23 %) patients had anemia, 37 (1 %) had polycythemia, 177 (9 %) had hypercalcemia, 51 (2 %) had recent-onset hypertension, and 224 (10 %) had liver dysfunction at time of nephrectomy. Patients with PNS were more likely to have high-grade tumors and advanced disease stages. A total of 675 (24 %) patients developed progression and 1171 (41 %) died of RCC, over a median follow-up of 8.2 years. On univariable analysis, the presence of any PNS was associated with inferior CSS [hazard ratio (HR) = 1.86, p = 0.007] and a trend toward shorter PFS (HR = 1.33, p = 0.07) compared with patients without PNS. Specifically, anemia, polycythemia, hypercalcemia, and liver dysfunction were each associated with inferior CSS and PFS (all p < 0.05). However, on multivariable analysis PNS (overall or each individual syndrome) did not remain independently associated with CSS or PFS.

CONCLUSIONS

Patients with RCC undergoing nephrectomy presenting with PNS have worse oncologic outcome than those with incidentally found tumors. However, the adverse outcome among PNS patients seems to be largely explained by adverse pathologic features of these tumors.

TRPM3 and miR-204 establish a regulatory circuit that controls oncogenic autophagy in clear cell renal cell carcinoma

Autophagy promotes tumor growth by generating nutrients from the degradation of intracellular structures. Here we establish, using shRNAs, a dominant-negative mutant, and a pharmacologic inhibitor, mefenamic acid (MFA), that the Transient Receptor Potential Melastatin 3 (TRPM3) channel promotes the growth of clear cell renal cell carcinoma (ccRCC) and stimulates MAP1LC3A (LC3A) and MAP1LC3B (LC3B) autophagy. Increased expression of TRPM3 in RCC leads to Ca(2+) influx, activation of CAMKK2, AMPK, and ULK1, and phagophore formation. In addition, TRPM3 Ca(2+) and Zn(2+) fluxes inhibit miR-214, which directly targets LC3A and LC3B. The von Hippel-Lindau tumor suppressor (VHL) represses TRPM3 directly through miR-204 and indirectly through another miR-204 target, Caveolin 1 (CAV1).

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.