High Frequency of SDHB Germline Mutations in Patients with Malignant Catecholamine-Producing Paragangliomas: Implications for Genetic Testing
Adrenal and extraadrenal paragangliomas are tumors of chromaffin cells that are usually benign but that may also develop into malignant disease. Mutations of the gene for succinate dehydrogenase subunit B (SDHB) are associated with a high risk of malignancy, but establishing the precise contribution requires relatively large numbers of patients with well-defined malignancy.
We assessed the prevalence of SDHB mutations in a series of patients with malignant paraganglioma.
SDHB mutation testing was carried out in 44 consecutive patients with malignant paraganglioma. Clinical characteristics of patients with malignant disease due to SDHB mutations were compared with those without mutations.
Pathogenic SDHB mutations were found in 13 of the 44 patients (30%). Close to one third of patients had metastases originating from an adrenal primary tumor, compared with a little over two thirds from an extraadrenal tumor. Among the latter patients, the frequency of SDHB mutations was 48%.
This study establishes that missense, nonsense, frameshift, and splice site mutations of the SDHB gene are associated with about half of all malignancies originating from extraadrenal paragangliomas. The high frequency of SDHB germline mutations among patients with malignant disease, particularly when originating from an extraadrenal paraganglioma, may justify a high priority for SDHB germline mutation testing in these patients.
Available from: Tsuyoshi Saito
- "I-MIBG negative pheochromocytoma 4440 Int J Clin Exp Pathol 2014;7(7):4438-4447 nancy  "
[Show abstract] [Hide abstract]
ABSTRACT: A 70-year-old Japanese woman was referred to our hospital due to hyperhidrosis and rapid weight loss of 10 kg in a month. A lump measuring 26 mm in diameter was detected in the left adrenal gland by computed tomography. Biochemical tests showed high levels of serum and urinary norepinephrine and epinephrine. However, a 123 I-MIBG scintigram failed to detect any accumulation in the left adrenal tumor. A left adrenalectomy was per-formed post clinical diagnosis of 123 I-MIBG negative pheochromocytoma. Microscopically, the tumor exhibited pheo-chromocytoma compatible features. Immunohistochemical analysis revealed low expression of VMAT1 in the tumor compared to the normal, surrounding tissue. To test for a possible genetic alteration of the monoamine transporter genes, we performed whole-exome sequencing of the VMAT1, VMAT2, and NET genes in the tumor. No significant base sequence substitution or deletion/insertion was found in any transporter. This suggests that MIBG negativ-ity is caused by a change that is independent of the base sequence abnormalities, such as an epigenetic change. Furthermore, a retrospective literature review of 123 I-MIBG negative-scintigraphy cases indicates that a negative finding in the 123 I-MIBG scintigram is frequently associated with metastatic pheochromocytomas or SDHB muta-tions. However, a SDHB/D gene mutation has not been identified in the reported case. Although the patient needs careful monitoring following the surgery, to date she has been disease free for 12 months. This study could not find clear reasons for negative conversion, however, investigations of the negative conversion mechanism might reveal significant insights towards the improvement of patient survival.
Available from: Svenja Nölting
- "However, the risk for metastatic disease in these tumors is relatively low and tumor resection is thus almost always curative. In contrast, the risk for malignant PHEOs/PGLs is particularly high in the case of succinate dehydrogenase B (SDHB) gene mutations , , and novel treatment strategies are urgently needed for this condition. "
[Show abstract] [Hide abstract]
ABSTRACT: To date, malignant pheochromocytomas and paragangliomas (PHEOs/PGLs) cannot be effectively cured and thus novel treatment strategies are urgently needed. Lovastatin has been shown to effectively induce apoptosis in mouse PHEO cells (MPC) and the more aggressive mouse tumor tissue-derived cells (MTT), which was accompanied by decreased phosphorylation of mitogen-activated kinase (MAPK) pathway players. The MAPK pathway plays a role in numerous aggressive tumors and has been associated with a subgroup of PHEOs/PGLs, including K-RAS-, RET-, and NF1-mutated tumors. Our aim was to establish whether MAPK signaling may also play a role in aggressive, succinate dehydrogenase (SDH) B mutation-derived PHEOs/PGLs. Expression profiling and western blot analysis indicated that specific aspects of MAPK-signaling are active in SDHB PHEOs/PGLs, suggesting that inhibition by statin treatment could be beneficial. Moreover, we aimed to assess whether the anti-proliferative effect of lovastatin on MPC and MTT differed from that exerted by fluvastatin, simvastatin, atorvastatin, pravastatin, or rosuvastatin. Simvastatin and fluvastatin decreased cell proliferation most effectively and the more aggressive MTT cells appeared more sensitive in this respect. Inhibition of MAPK1 and 3 phosphorylation following treatment with fluvastatin, simvastatin, and lovastatin was confirmed by western blot. Increased levels of CASP-3 and PARP cleavage confirmed induction of apoptosis following the treatment. At a concentration low enough not to affect cell proliferation, spontaneous migration of MPC and MTT was significantly inhibited within 24 hours of treatment. In conclusion, lipophilic statins may present a promising therapeutic option for treatment of aggressive human paragangliomas by inducing apoptosis and inhibiting tumor spread.
Available from: Roberto Dina
- "Moreover scoring methods for predicting malignant behaviour are not entirely reproducible (Agarwal et al, 2010) and lack correlation with genotype (Eisenhofer et al, 2012). Genetic analysis, although useful, only gives partial information for risk stratification: for example, although it is known that SDH-B mutation carriers (representing up to 7% of the patients presenting with PCC/PGL disease) will suffer from a higher lifelong chance of recurrence or malignant dedifferentiation than compared with other paraganglioma syndromes (Brouwers et al, 2006), the course of the disease can still be highly variable with some mutation carriers presenting with highly aggressive and malignant disease, and others presenting with indolent or even no detectable disease (Gimenez-Roqueplo et al, 2006; Srirangalingam et al, 2008). Genome-wide expression profile studies have shed some light upon the pathophysiology of PCC/PGL. "
[Show abstract] [Hide abstract]
There are no reliable markers of malignancy in phaeochromocytomas (PCC) and paragangliomas (PGL). We investigated the relevance of the mammalian target of rapamycin (mTOR)/AKT and hypoxic pathways as novel immunohistochemical markers of malignancy.
Tissue microarray blocks were constructed with a total of 100 tumours (10 metastatic) and 20 normal adrenomedullary samples. Sections were immunostained for hypoxia-inducible factor 1α (Hif-1α), vascular endothelial growth factor A (VEGF-A), mTOR, carbonic anhydrase IX (CaIX) and AKT. The predictive performance of these markers was studied using univariate, multivariate and receiver operating characteristic analyses.
In all, 100 consecutive patients, 64% PCC, 29% familial with a median tumour size of 4.7 cm (range 1–14) were included. Univariate analyses showed Hif-1α overexpression, tumour necrosis, size >5 cm, capsular and vascular invasion to be predictors of metastasis. In multivariate analysis, Hif-1α, necrosis and vascular invasion remained as independent predictors of metastasis. Hif-1α was the most discriminatory biomarker for the presence of metastatic diffusion. Strong membranous CaIX expression was seen in von Hippel–Lindau (VHL) PCC as opposed to other subtypes.
Lack of vascular invasion, tumour necrosis and low Hif-1α expression identify tumours with lower risk of malignancy. We propose membranous CaIX expression as a potential marker for VHL disease in patients presenting with PCC.
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.