Frequent activating FGFR2 mutations in endometrial carcinomas parallel germline mutations associated with craniosynostosis and skeletal dysplasia syndromes

Endometrial carcinoma is the most common gynecological malignancy in the United States. Although most women present with early disease confined to the uterus, the majority of persistent or recurrent tumors are refractory to current chemotherapies. We have identified a total of 11 different FGFR2 mutations in 3/10 (30%) of endometrial cell lines and 19/187 (10%) of primary uterine tumors. Mutations were seen primarily in tumors of the endometrioid histologic subtype (18/115 cases investigated, 16%). The majority of the somatic mutations identified were identical to germline activating mutations in FGFR2 and FGFR3 that cause Apert Syndrome, Beare-Stevenson Syndrome, hypochondroplasia, achondroplasia and SADDAN syndrome. The two most common somatic mutations identified were S252W (in eight tumors) and N550K (in five samples). Four novel mutations were identified, three of which are also likely to result in receptor gain-of-function. Extensive functional analyses have already been performed on many of these mutations, demonstrating they result in receptor activation through a variety of mechanisms. The discovery of activating FGFR2 mutations in endometrial carcinoma raises the possibility of employing anti-FGFR molecularly targeted therapies in patients with advanced or recurrent endometrial carcinoma.

Lack of augmentation of tumor spectrum or severity in dual heterozygous Men1 and Rb1 knockout mice

To identify possible genetic interactions between the mechanisms of tumor suppression of menin and pRb, we intercrossed mice with targeted deletions of Men1 and Rb1, and compared tumor development in cohorts of animals carrying single or dual mutations of these tumor-suppressor genes. In mice lacking one copy of Men1, pancreatic islet and anterior pituitary adenomas are common. In animals lacking one copy of Rb1, intermediate pituitary and thyroid tumors occur at high frequency, with less frequent development of pancreatic islet hyperplasia and parathyroid lesions. In mice heterozygous for both Men1 and Rb1, pancreatic hyperplasia and tumors of the intermediate pituitary and thyroid occurred at high frequency. Serum measurements of calcium and glucose did not vary significantly between genotypic groups. Loss of heterozygosity at the Rb1 locus was common in pituitary and thyroid tumors, whereas loss of menin was observed in pancreatic and parathyroid lesions. The tumor spectrum in the double heterozygotes was a combination of pathologies seen in each of the individual heterozygotes, without decrease in age of onset, indicating independent, non-additive effects of the two mutations. Together with the lack of increased tumor spectrum, this suggests that menin and pRb function in a common pathway of tumor suppression.

Evidence for persistent dysfunction of wild-type aldosterone synthase gene in glucocorticoid-treated familial hyperaldosteronism type I

BACKGROUND

In familial hyperaldosteronism type I (FH-I), glucocorticoid treatment suppresses adrenocorticotrophic hormone-regulated hybrid gene expression and corrects hyperaldosteronism.

OBJECTIVE

To determine whether the wild-type aldosterone synthase genes, thereby released from chronic suppression, are capable of functioning normally.

METHODS

We compared mid-morning levels of plasma potassium, plasma aldosterone, plasma renin activity (PRA) and aldosterone: PRA ratios, measured with patients in an upright position, and responsiveness of aldosterone levels to infusion of angiotensin II (AII), for 11 patients with FH-I before and during long-term (0.8-14.3 years) treatment with 0.25-0.75 mg/day dexamethasone or 2.5-10 mg/day prednisolone.

RESULTS

During glucocorticoid treatment, hypertension was corrected in all. Potassium levels, which had been low (< 3.5 mmol/l) in two patients before treatment, were normal in all during treatment (mean 4.0+/-0.1 mmol/l, range 3.5-4.6). Aldosterone levels during treatment [13.2+/-2.1 ng/100 ml (mean+/-SEM)] were lower than those before treatment (20.1+/-2.5 ng/100 ml, P< 0.05). PRA levels, which had been suppressed before treatment (0.5+/-0.2 ng/ml per h), were unsuppressed during treatment (5.1+/-1.5 ng/ml per h, P< 0.01) and elevated (> 4 ng/ml per h) in six patients. Aldosterone: PRA ratios, which had been elevated (> 30) before treatment (101.1+/-25.9), were much lower during treatment (4.1+/-1.0, P< 0.005) and below normal (< 5) in eight patients. Surprisingly, aldosterone level, which had not been responsive (< 50% rise) to infusion of AII for all 11 patients before treatment, remained unresponsive for 10 during treatment.

CONCLUSIONS

Apparently regardless of duration of glucocorticoid treatment in FH-I, aldosterone level remains poorly responsive to AII, with a higher than normal PRA and a low aldosterone: PRA ratio. This is consistent with there being a persistent defect in functioning of wild-type aldosterone synthase gene.

A PCR-based method of screening individuals of all ages, from neonates to the elderly, for familial hyperaldosteronism type I

AIM

Unless specifically treated (glucocorticoids in low doses), Familial Hyperaldosteronism Type I (FH-I) may result in early death from stroke. We report the successful application of a rapid, polymerase chain reaction (PCR)-based method of detecting the 'hybrid' 11 beta-hydroxylase (11 beta-OHase)/aldosterone synthase (AS) gene as a screening test for FH-I.

METHODS

'Long-PCR' was used to amplify, concurrently, a 4 kb fragment of AS gene (both primers AS-specific) and a 4 kb fragment of the hybrid gene (5' primer 11 beta-OHase-specific, 3' primer AS-specific) from DNA extracted from blood either collected locally or transported from elsewhere. Sample collection and transport were straightforward. This 4 kb fragment contains all the currently recognised hybrid gene 'crossover' points.

RESULTS

Within a single family, long-PCR identified all 21 individuals known to have FH-I. Hypertension was corrected in all 11 treated with glucocorticoids. Nine with normal blood pressure are being closely followed for development of hypertension. Long-PCR cord blood analysis excluded FH-I in three neonates born to affected individuals. Long-PCR newly identified two other affected families: (1) a female (60 years) with a personal and family history of stroke and her normotensive daughter (40 years), and (2) a female (51 years) previously treated for primary aldosteronism with amiloride, her two hypertensive sons (14 and 16 years) and her hypertensive mother (78 years). No false negative or false positive results have yet been encountered. At least seven other centres have successfully performed this test.

CONCLUSION

Long-PCR is a reliable method of screening individuals of all ages for FH-I.

In familial hyperaldosteronism type I, hybrid gene-induced aldosterone production dominates that induced by wild-type genes

We compared the aldosterone-producing potency of the angiotensin II-sensitive wild-type aldosterone synthase genes and the ACTH-sensitive hybrid 11 beta-hydroxylase/aldosterone synthase gene by examining aldosterone, PRA, and cortisol day-curves (2-hourly levels over 24 h) in patients with familial hyperaldosteronism type I, before and during long-term (0.8-13.5 yr) glucocorticoid treatment. In 8 untreated patients, PRA levels were usually suppressed, and aldosterone correlated strongly with cortisol (r = 0.69-0.99). Fourteen studies were performed on 10 patients receiving glucocorticoid treatment that corrected hypertension, hypokalemia, and PRA suppression in all. ACTH was markedly and continuously suppressed in 6 studies, 3 of which demonstrated strong correlations between aldosterone and PRA (r = 0.77-0.92). ACTH was only partially suppressed in the remaining 8 studies; aldosterone correlated strongly: 1) with cortisol alone in 5 (r = 0.71-0.98); 2) with cortisol (r = 0.90) and PRA (r = 0.74) in one; 3) with PRA only in one (r = 0.80); and 4) with neither PRA nor cortisol in one. Unless ACTH is markedly and continuously suppressed, aldosterone is more responsive to ACTH than to renin/angiotensin II, despite the latter being unsuppressed. This is consistent with the hybrid gene being more powerfully expressed than the wild-type aldosterone synthase genes in familial hyperaldosteronism type I.

Increased resistance to Anaplasma marginale infection in cattle chronically infected with Theileria buffeli (syn. T. orientalis)

Calves chronically infected with the benign haemoprotozoan parasite Theileria buffeli (syn. T. orientalis) and T. buffeli-free calves were experimentally infected with virulent Anaplasma marginale. The daily mean maximum parasitaemia in the T. buffeli-carrier calves was lower and delayed relative to that of the Theileria-free calves. Anaemia was less marked in the Theileria infected calves, although this difference was not statistically significant. The susceptibility of Theileria-carrier and Theileria-free older cattle to virulent A. marginale infection was also investigated. The mean maximum parasitaemia observed in the Theileria-infected cattle was significantly lower than that of the Theileria-free cattle and the time to maximum parasitaemia was increased significantly in the Theileria-infected relative to the Theileria-free cattle. Of the Theileria-carrier cattle, 33% exhibited maximum parasitaemias of less than 0.1% infected erythrocytes and no clinical anaemia as a result of A. marginale infection. In contrast, the lowest maximum parasitaemia observed in the Theileria-free cattle was 7%. The percentage of cattle requiring treatment to prevent mortality due to anaemia was 50% and 91% in the Theileria-infected and Theileria-free cattle respectively. For the duration of increasing A. marginale parasitaemia, the level of Theileria in carrier cattle was significantly depressed or undetectable. Following the resolution of peak A. marginale parasitaemia, the level of Theileria parasites increased rapidly to become significantly higher than that prior to infection and then decreased gradually to a level similar to that prior to infection. The mechanism of the increased resistance to A. marginale infection conferred by T. buffeli-carrier state is unknown, but is likely to involve non-specific cell-mediated immunity, as no serological cross-reactivity exists between these two highly divergent parasite species. The susceptibility of relatively mature cattle to clinical anaplasmosis under field conditions is likely to be significantly affected by the widespread distribution and common occurrence of T. buffeli throughout the range of A. marginale in Australia, Africa and southeast Asia.

Peripheral blood lymphocyte proliferative responses in cattle infected with or vaccinated against Anaplasma marginale

An assay was developed for measurement of the peripheral blood lymphocyte proliferative response (PBLPR) in cattle infected with or immunised against Anaplasma marginale. PBLPR was not evident in all cattle that had recovered from A. marginale infection. However, A. marginale-sensitised lymphocytes were detected in the spleens of all immune cattle tested in the absence of detectable PBLPR. During the course of initial infection, cattle exhibited detectable PBLPR for a period corresponding with and up to 2 weeks after patent parasitaemia, followed by a second, usually larger peak in PBLPR corresponding to the time of sub-clinical relapse of cattle. Analysis of the PBLPR of A. marginale chronically infected cattle demonstrated highly variable PBLPR between individuals and over time. A positive PBLPR was induced in cattle by vaccination using a crude A. marginale antigen preparation. The PBLPR of vaccinated cattle subsequently infected with A. marginale was markedly different from that of naive cattle, with reduced PBLPR being associated with the onset of parasitaemia. The antigen used in the PBLPR assay was inactivated by proteolysis. Proteolysis also abolished immunity that had been induced in cattle vaccinated using the antigen preparation. A marginale-sensitised PBL did not proliferate in response to antigen from the heterologous species A. centrale. A. centrale-sensitised PBL, however, responded to A. marginale antigen. Interferon-gamma (IFN-gamma) was detected in PBLPR-assay supernatants and was associated with a strong PBLPR.