DNA methylation profiling in MEN1-related pancreatic neuroendocrine tumors reveals a potential epigenetic target for treatment

OBJECTIVE

Epigenetic changes contribute to pancreatic neuroendocrine tumor (PanNET) development. Hypermethylation of promoter DNA as a cause of tumor suppressor gene silencing is a well-established oncogenic mechanism that is potentially reversible and therefore an interesting therapeutic target. Multiple endocrine neoplasia type 1 (MEN1) is the most frequent cause of inherited PanNETs. The aim of this study was to determine promoter methylation profiles in MEN1-related PanNETs.

DESIGN AND METHODS

Methylation-specific multiplex ligation-dependent probe amplification was used to assess promoter methylation of 56 tumor suppressor genes in MEN1-related (n = 61) and sporadic (n = 34) PanNETs. Differences in cumulative methylation index (CMI), individual methylation percentages and frequency of promoter hypermethylation between subgroups were analyzed.

RESULTS

We found promoter methylation of a large number of potential tumor suppressor genes. CMI (median CMI: 912 vs 876, P = 0.207) was the same in MEN1-related and sporadic PanNETs. We found higher methylation percentages of CASP8 in MEN1-related PanNETs (median: 59% vs 16.5%, P = 0.002). In MEN1-related non-functioning PanNETs, the CMI was higher in larger PanNETs (>2 cm) (median: 969.5 vs 838.5; P = 0.021) and in PanNETs with liver metastases (median: 1036 vs 869; P = 0.013). Hypermethylation of MGMT2 was more frequent in non-functioning PanNETs compared to insulinomas (median: 44.7% vs 8.3%; P = 0.022). Hypermethylation of the Von Hippel-Lindau gene promoter was observed in one MEN1-related PanNET and was associated with loss of protein expression.

CONCLUSION

Promoter hypermethylation is a frequent event in MEN1-related and sporadic PanNETs. Targeting DNA methylation could be of therapeutic value in MEN1 patients with advanced PanNETs.

[Relatively poor regulation of blood pressure in patients with type-2 diabetes mellitus in the primary care setting and specialists' practice in the Netherlands]

OBJECTIVE

To investigate the degree to which the goals for adequate blood-pressure control in patients with type-2 diabetes mellitus (DM) are met in Dutch specialists' practice and in the primary-care setting.

DESIGN

Cross sectional.

METHOD

Data were collected from all consecutive patients with DM type 2 visiting the outpatient clinic of two physicians specialised in diabetes care, in Zwolle, the Netherlands, in the period 1 November 1999-30 April 2000. The target value for blood pressure was < or = 150/85 mmHg. In addition, baseline data were collected on patients in the primary-care setting who participated in a transmural project in Zwolle in the period 1 February 1997-31 January 1998. In 1998, the target blood pressure in the primary-care setting was < or = 160/90 mmHg. Patients who met the goals for adequate blood-pressure control were compared with patients who did not.

RESULTS

A total of 502 patients from specialists' practice and 1084 patients from the primary-care setting were included. The prevalence of hypertension in specialists' practice was 89% (n = 377); of these patients, 140 (37%) had a good regulation of their blood pressure. The patients who had an adequate blood-pressure control and those who did not were comparable. Both groups were prescribed an average of 2.2 kinds of antihypertensive agent per patient. The prevalence of hypertension in the primary care was 69% (n = 733). The goal for adequate blood-pressure control, i.e. a blood pressure of < or = 160/90 mmHg, was achieved in 44% (n = 324). In the primary-care setting, an average of 1.1 kinds of antihypertensive agent was prescribed, 1.6 in patients who achieved the target value and 0.8 in those who did not (p < 0.05).

CONCLUSION

Regulation of blood pressure in patients with type 2 DM and hypertension was far from optimal: 37% of patients in specialists' practice and 44% of those in the primary-care setting achieved the target values.