Blocking ETV6/RUNX1-induced MDM2 overexpression by Nutlin-3 reactivates p53 signaling in childhood leukemia.

ETV6/RUNX1 (E/R) is the most common fusion gene in childhood acute lymphoblastic leukemia. It is responsible for the initiation of leukemia but also indispensable for disease maintenance and propagation, although its function in these latter processes is less clear. We therefore investigated the effects of the perceived p53 pathway alterations in model cell lines and primary leukemias and, in particular, how E/R upregulates MDM2, the predominant negative regulator of p53. We found that E/R transactivates MDM2 in both p53(+/+) and p53(-/-) HCT116 cells by binding to promoter-inherent RUNX1 motifs, which indicates that this activation occurs in a direct and p53-independent manner. Treatment of E/R-positive leukemic cell lines with Nutlin-3, a small molecule that inhibits the MDM2/p53 interaction, arrests their cell cycle and induces apoptosis. These phenomena concur with a p53-induced expression of p21, pro-apoptotic BAX and PUMA, as well as caspase 3 activation and poly ADP-ribose polymerase cleavage. The addition of DNA-damaging and p53-activating chemotherapeutic drugs intensifies apoptosis. Moreover, Nutlin-3 exposure leads to an analogous p53 accumulation and apoptotic surge in E/R-positive primary leukemic cells. Our findings clarify the role of p53 signaling in E/R-positive leukemias and outline the potential basis for its therapeutic exploitation in this setting.

CREBBP HAT domain mutations prevail in relapse cases of high hyperdiploid childhood acute lymphoblastic leukemia.

Despite their apparently good prognosis ∼15% of high hyperdiploid (HD) childhood acute lymphoblastic leukemia (ALL) cases relapse. To search for responsible risk factors we determined copy number aberrations as well as copy neutral loss of heterozygosity (LOH) in 13 matched diagnosis and relapse samples and added the data of the only three available cases from the literature. Deletions and copy neutral LOH in 3 and 2 of the 16 cases directed us to the histone-modifying CREB-binding protein (CREBBP) gene, whose functional impairment is implicated in drug resistance. We therefore screened all samples for mutations in this gene and discovered 9 acquired sequence mutations in 7/16 cases, leading to an overall frequency of somatic CREBBP aberrations in HD ALL relapse cases of 63% that is considerably higher than that of the reported, mainly non-HD ALL (18.3%). Moreover, mutations in HD cases occur almost exclusively in the HAT domain (8/9; 89%). Hot spot mutations are present at diagnosis in 18.8% of relapsing HD ALL cases but in none of 40 respective cases remaining in long-term remission. Thus, the particular high incidence of CREBBP mutations in relapse-prone HD ALL cases could eventually be exploited for refined risk stratification and customized treatment in this genetic subgroup.

The prevalence of familial hyperaldosteronism in apparently sporadic primary aldosteronism in Germany: a single center experience.

Primary aldosteronism (PA) is the most frequent cause of secondary arterial hypertension. To date 3 forms of familial hyperaldosteronism (FH) have been described accounting for a small percentage of all PA cases. In Germany, the prevalence of FH is currently unknown. Our aim was to determine the prevalence of familiarity in a large cohort of patients with PA. A total of 166 patients with apparently sporadic PA in Munich were investigated. FH types I, II, and III were identified using established clinical, biochemical, and molecular criteria. Among the 166 patients with PA, 2 patients (1.2%) reported a family history suggestive of FH. None of the 166 patients showed clinical, endocrine, or genetic evidence of FH type I. The 2 families had characteristic features of FH type II. Family A had 3 subjects affected out of 11 evaluated family members. Family B had 3 out of 4. Bilateral adrenal hyperplasia and unilateral adrenal adenoma were found within the same family. FH type I and FH type III are rare in Germany. With a prevalence of 1.2%, FH type II seems to be more common in apparently sporadic PA than had been assumed so far.

MUTYH-associated polyposis - variability of the clinical phenotype in patients with biallelic and monoallelic MUTYH mutations and report on novel mutations.

To further characterize 215 APC mutation-negative patients with colorectal neoplasias classified in classical, attenuated, or atypical familial adenomatous polyposis (FAP) coli we performed mutation screening in the Mut Y homologue (MUTYH) gene. The incidence was 15% for biallelic and 3.7% for monoallelic MUTYH mutations. We describe six novel MUTYH mutations in biallelic constellation and two novel monoallelic missense mutations. Of 33 MUTYH-associated polyposis coli (MAP) patients 57% were attenuated familial adenomatous polyposis (AFAP) patients, 10% display early-onset classical FAP and 18% had only few adenomas at higher age. Biallelic cases had a high incidence of extracolonic polyposis in 32% and colorectal cancer (CRC) in 33% of the cases. The clinical picture of MAP ranged from classical FAP or synchronous CRC at age 30 years to few adenomas at age 54 years without evidence of CRC, initially suspected for hereditary non-polyposis colorectal cancer (HNPCC). The mean age of onset was 43 years, with 11 (33%) patients being younger than 40 years of age, indicating that the clinical manifestation can be earlier than so far reported. Monoallelic MUTYH mutation carriers had a positive family history in seven of eight cases allowing the hypothesis of a disease-causing synergism of MUTYH mutations with other genes.

Staging for locally advanced pancreatic cancer.

AIM: To address the role of a dedicated radiologist and high quality CT scanning in staging of patients referred with suspected locally advanced pancreatic cancer. Furthermore, the value of laparoscopy in detecting CT-occult metastases in these patients was assessed. METHODS: In a prospective cohort study, 116 patients with suspected unresectable pancreatic cancer referred from peripheral hospitals (107) or our own gastroenterology department (9) were analysed. CT scans from referral centres were reviewed and in case of locally advanced disease or uncertain metastatic disease, patients underwent a laparoscopy to detect CT-occult metastases. Patients without metastases were offered 5-FU based chemoradiotherapy. RESULTS: After reviewing 107 abdominal CT scans from referral centres, 73 (68%) scans had to be repeated due to unacceptable quality. Locally advanced disease was confirmed in 59 (55%) patients and metastatic disease was found in 24 patients (22%). During laparoscopy, metastases were found in 24/68 (35%) patients with locally advanced disease on CT scan and metastases were confirmed in 3/5 (60%) with suspected metastases. Overall, only 46/116 (40%) patients with suspected unresectable disease appeared to have locally advanced pancreatic cancer after adequate staging including laparoscopy in our centre. CONCLUSION: Correct staging is difficult in patients with suspected locally advanced pancreatic cancer and should preferably be performed in centres with technically advanced equipment and experienced radiologists. Laparoscopy should be offered to patients before locoregional therapy.

[Hereditary nonpolyposis colorectal carcinoma: state of the art]. / Hereditäre nicht-polypöse kolorektale Karzinome: Aktueller Stand.

Familial clustering is found in 20-25% of all cases with colorectal cancer (CRC), 4-5% revealing autosomal dominant inheritance. Hereditary CRC develops from adenomatous, hyperplastic hamartomatous juvenile lesions. Hereditory nonpolyposis colorectal cancer includes two genetically different tumor entities, those with and without microsatellite instability in the corresponding tumors. Those with such instability and with germ-line mutation in DNA mismatch repair genes (Lynch syndrome) have additional neoplasms, an earlier age at onset and a higher risk for syn- and metachronous cancers.