PU.1 downregulation within hematopoietic stem and progenitor cells (HSPCs) is the primary mechanism for the development of acute myeloid leukemia (AML) in mice with homozygous deletion of the upstream regulatory element (URE) of PU.1 gene. p53 is a well-known tumor suppressor that is often mutated in human hematologic malignancies including AML and adds to their aggressiveness; however, its genetic deletion does not cause AML in mouse. Deletion of p53 in the PU.1(ure/ure) mice (PU.1(ure/ure)p53(-/-)) results in more aggressive AML with shortened overall survival. PU.1(ure/ure)p53(-/-) progenitors express significantly lower PU.1 levels. In addition to URE deletion we searched for other mechanisms that in the absence of p53 contribute to decreased PU.1 levels in PU.1(ure/ure)p53(-/-) mice. We found involvement of Myb and miR-155 in downregulation of PU.1 in aggressive murine AML. Upon inhibition of either Myb or miR-155 in vitro the AML progenitors restore PU.1 levels and lose leukemic cell growth similarly to PU.1 rescue. The MYB/miR-155/PU.1 axis is a target of p53 and is activated early after p53 loss as indicated by transient p53 knockdown. Furthermore, deregulation of both MYB and miR-155 coupled with PU.1 downregulation was observed in human AML, suggesting that MYB/miR-155/PU.1 mechanism may be involved in the pathogenesis of AML and its aggressiveness characterized by p53 mutation.

Atypical polypoid adenomyoma (APA) is an uncommon uterine lesion that commonly recurs after local excision and is occasionally associated with or precedes the development of atypical hyperplasia or endometrioid adenocarcinoma. Despite the fact that about 230 cases have been reported in the literature, only 2 studies of 6 and of 7 cases have investigated the molecular aspects; as such, molecular alterations that occur in APA remain largely unknown. We undertook a comprehensive immunohistochemical and molecular analysis of 21 cases of APA in 17 patients (including 4 recurrent/persistent lesions). The analyzed genes were PTEN and TP53 (by fluorescence in situ hybridization) and KRAS, BRAF, EGFR, and NRAS (all by polymerase chain reaction). Immunohistochemical staining was performed for PTEN, p53, mTOR, β-catenin, HNF-1β, and GLUT1 and for the mismatch-repair proteins MLH-1, MSH-2, MSH-6, and PMS-2. In most cases, there was nuclear expression of β-catenin in squamous morules and expression of HNF-1β, mTOR, and GLUT1 in the glandular component. All cases exhibited "wild-type" expression of p53. A common finding was loss of PTEN expression (6/19 cases). In 1 of these cases, loss of PTEN expression was accompanied by PTEN deletion. Mutation of the KRAS gene was found in 5/19 cases. Intact mismatch-repair protein expression was present in all cases, and TP53 abnormalities or mutations of EGFR, NRAS, or BRAF genes were not found. Given the association with atypical hyperplasia and endometrioid adenocarcinoma and the shared immunohistochemical and molecular features, we feel that, conceptually, APA is best regarded as analogous to a localized form of atypical hyperplasia.

In the current study, the sensitivity and specificity of methods of HER2 status detection were studied in 55 patients presenting with gastric/gastroesophageal junction carcinoma (30 intestinal and 25 diffuse), in small biopsy (endoscopy; n=33) and resection specimens (n=22). The primary objective of the present study was to compare various methods for the assessment of HER2 status, with regards to the sensitivity and specificity of each method, as well as their concordance. In all cases, the status of HER2 was determined using immunohistochemistry (IHC), fluorescence in situ hybridization (FISH), silver in situ hybridization (SISH), and quantitative polymerase chain reaction (qPCR). The concordance rate between IHC and ISH was 100% for IHC 0 and 3+. The concordance rate for IHC 1+ was 100% between IHC and SISH, and 92.9% between IHC and FISH. The concordance rate among different FISH methods was 100%, between FISH and SISH it was 96.2%, and between qPCR and ISH methods it was 88.5%. Thus, the results demonstrate that different in situ hybridization methods are comparable and that none were superior. Furthermore, the IHC and FISH methods were found to be comparable and the concordance rate was particularly good. qPCR analysis correlated well with the other methods and appears to be a possible alternative tool for detection of the HER2 status. However, the concordance rate of qPCR with other methods was identified to be lower in the diffuse carcinoma group of endoscopy biopsy specimens; therefore investigation of further cases is required.

Abstract. Her2 proto-oncogene amplification and protein overexpression is observed in 20-40% of patients with breast cancer and plays a crucial role in invasive breast cancer and its treatment. In the present study, we investigated samples from 131 patients with invasive breast carcinoma. In all cases, the overexpression/amplification level of Her2 was determined using manual immunohistochemistry (IHC) and/or automatic IHC, fluorescence in situ hybridization (FISH), silver in situ hybridization (SISH) and quantitative polymerase chain reaction (qPCR). Using various methods, we demonstrated candidate methods for Her2 detection and their dependability. Our results demonstrate that these methods are highly comparable for the detection of Her2 overexpression/amplification. It was also revealed that qPCR is a valuable tool for the evaluation of Her2 gene overexpression/amplification. The results from pPCR analysis positively correlated with the results from IHC and FISH analysis. Moreover, in contrast to IHC or SISH/ FISH, the results obtained by qPCR were not encumbered with any subjective error on the part of the evaluator.