The hallmarks of cancer: relevance to the pathogenesis of polycystic kidney disease

Glioma in Patients with Autosomal-Dominant Polycystic Kidney Disease

BACKGROUND

Autosomal-dominant polycystic kidney disease (ADPKD) is an inherited systemic condition with a predominant feature of cyst formation in both kidneys. An association with intracranial glioma has not been described previously in ADPKD.

CASE DESCRIPTION

We report 2 cases of glioma in patients with ADPKD. One patient had a cystic lesion with contrast enhancement in the right temporal lobe as revealed by magnetic resonance imaging and an aneurysm in left sylvian fissure confirmed by computed tomography angiography. Subsequent histopathologic analysis of the resected enhancing lesion confirmed the diagnosis of glioblastoma (World Health Organization grade IV). The second patient was found to harbor a solid lesion in the right parietal lobe. This lesion also proved to be an astrocytoma (World Health Organization grade II).

CONCLUSIONS

These 2 independent cases of glioma suggest an unusual clinical manifestation of ADPKD. The potential association between ADPKD and glioma pathogenesis should be further explored.

Neoexpression of a functional primary cilium in colorectal cancer cells

The Hedgehog (HH) signaling pathway is involved in the maintenance of numerous cell types both during development and in the adult. Often deregulated in cancers, its involvement in colorectal cancer has come into view during the last few years, although its role remains poorly defined. In most tissues, the HH pathway is highly connected to the primary cilium (PC), an organelle that recruits functional components and regulates the HH pathway. However, normal epithelial cells of the colon display an inactive HH pathway and lack a PC. In this study, we report the presence of the PC in adenocarcinoma cells of primary colorectal tumors at all stages. Using human colorectal cancer cell lines we found a clear correlation between the presence of the PC and the expression of the final HH effector, GLI1, and provide evidence of a functional link between the two by demonstrating the recruitment of the SMO receptor to the membrane of the primary cilium. We conclude that the primary cilium directly participates in the HH pathway in colorectal cancer cells.

Papillary renal cell carcinoma with a somatic mutation in MET in a patient with autosomal dominant polycystic kidney disease

Autosomal-dominant polycystic kidney disease (ADPKD) is caused by mutations in PKD1 and PKD2 and is characterized by proliferation of renal tubular epithelium and progressive chronic kidney disease. Derangements in similar cellular signaling pathways occur in ADPKD and renal malignancies, although an association of these disorders has not been established. Herein, we present a case of papillary RCC (pRCC) incidentally discovered in a patient with ADPKD following bilateral native nephrectomy during renal transplantation. Whole exome sequencing of the pRCC found a somatic missense mutation in MET proto-oncogene, p.Val1110Ile, not present in kidney cyst epithelium or non-cystic tissue. RNA sequencing demonstrated increased mRNA expression of MET and pathway-related genes, but no significant copy number variation of MET was detected. Genetic analysis of PKD genes from peripheral blood lymphocytes and renal cyst epithelium identified a constitutional PKD1 germline mutation, p.Trp1582Ser, predicted to be pathogenic. Unique somatic mutations in PKD1 were also detected in 80% of the renal cysts analyzed, but not in the pRCC. These results suggest that, in this patient, the pRCC utilized a signaling pathway involving MET that was distinct from the pathogenesis of ADPKD. This is the first report of PKD1 mutations and a somatic mutation of the MET oncogene in a pRCC in ADPKD.

Opposing Effects of Inhibitors of Aurora-A and EGFR in Autosomal-Dominant Polycystic Kidney Disease

Aurora-A kinase (AURKA) overexpression in numerous tumors induces aneuploidy, in part because of cytokinetic defects. Alisertib and other small-molecule inhibitors targeting AURKA are effective in some patients as monotherapies or combination therapies. Epidermal growth factor receptor (EGFR) pro-proliferative signaling activity is commonly elevated in cancer, and the EGFR inhibitor erlotinib is commonly used as a standard of care agent for cancer. An erlotinib/alisertib combination therapy is currently under assessment in clinical trials, following pre-clinical studies that indicated synergy of these drugs in cancer. We were interested in further exploring the activity of this drug combination. Beyond well-established functions for AURKA in mitotic progression, additional non-mitotic AURKA functions include control of ciliary stability and calcium signaling. Interestingly, alisertib exacerbates the disease phenotype in mouse models for autosomal-dominant polycystic kidney disease (ADPKD), a common inherited syndrome induced by aberrant signaling from PKD1 and PKD2, cilia-localized proteins that have calcium channel activity. EGFR is also more active in ADPKD, making erlotinib also of potential interest in this disease setting. In this study, we have explored the interaction of alisertib and erlotinib in an ADPKD model. These experiments indicated erlotinib-­restrained cystogenesis, opposing alisertib action. Erlotinib also interacted with alisertib to regulate proliferative signaling proteins, albeit in a complicated manner. Results suggest a nuanced role of AURKA signaling in different pathogenic conditions and inform the clinical use of AURKA inhibitors in cancer patients with comorbidities.

The cpk model of recessive PKD shows glutamine dependence associated with the production of the oncometabolite 2-hydroxyglutarate

Since polycystic kidney disease (PKD) was first noted over 30 years ago to have neoplastic parallels, there has been a resurgent interest in elucidating neoplasia-relevant pathways in PKD. Taking a nontargeted metabolomics approach in the B6(Cg)-Cys1(cpk/)J (cpk) mouse model of recessive PKD, we have now characterized metabolic reprogramming in these tissues, leading to a glutamine-dependent TCA cycle shunt toward total 2-hydroxyglutarate (2-HG) production in cpk compared with B6 wild-type kidney tissue. After confirmation of increased 2-HG expression in immortalized collecting duct cpk cells as well as in human autosomal recessive PKD tissue using targeted analysis, we show that the increase in 2-HG is likely due to glutamine-sourced α-ketoglutarate. In addition, cpk cells require exogenous glutamine for growth such that inhibition of glutaminase-1 decreases cell viability as well as proliferation. This study is a demonstration of the striking parallels between recessive PKD and cancer metabolism. Our data, once confirmed in other PKD models, suggest that future therapeutic approaches targeting this pathway, such as using glutaminase inhibitors, have the potential to open novel treatment options for renal cystic disease.