Expression of Abelson interactor 1 (Abi1) correlates with inflammation, KRAS mutation and adenomatous change during colonic carcinogenesis.

BACKGROUND: Abelson interactor 1 (Abi1) is an important regulator of actin dynamics during cytoskeletal reorganization. In this study, our aim was to investigate the expression of Abi1 in colonic mucosa with and without inflammation, colonic polyps, colorectal carcinomas (CRC) and metastases as well as in CRC cell lines with respect to BRAF/KRAS mutation status and to find out whether introduction of KRAS mutation or stimulation with TNFalpha enhances Abi1 protein expression in CRC cells. METHODOLOGY/PRINCIPAL FINDINGS: We immunohistochemically analyzed Abi1 protein expression in 126 tissue specimens from 95 patients and in 5 colorectal carcinoma cell lines with different mutation status by western immunoblotting. We found that Abi1 expression correlated positively with KRAS, but not BRAF mutation status in the examined tissue samples. Furthermore, Abi1 is overexpressed in inflammatory mucosa, sessile serrated polyps and adenomas, tubular adenomas, invasive CRC and CRC metastasis when compared to healthy mucosa and BRAF-mutated as well as KRAS wild-type hyperplastic polyps. Abi1 expression in carcinoma was independent of microsatellite stability of the tumor. Abi1 protein expression correlated with KRAS mutation in the analyzed CRC cell lines, and upregulation of Abi1 could be induced by TNFalpha treatment as well as transfection of wild-type CRC cells with mutant KRAS. The overexpression of Abi1 could be abolished by treatment with the PI3K-inhibitor Wortmannin after KRAS transfection. CONCLUSIONS/SIGNIFICANCE: Our results support a role for Abi1 as a downstream target of inflammatory response and adenomatous change as well as oncogenic KRAS mutation via PI3K, but not BRAF activation. Furthermore, they highlight a possible role for Abi1 as a marker for early KRAS mutation in hyperplastic polyps. Since the protein is a key player in actin dynamics, our data encourages further studies concerning the exact role of Abi1 in actin reorganization upon enhanced KRAS/PI3K signalling during colonic tumorigenesis.

Apoptosis: a key effector mechanism of lymphocyte action in human nonseminomatous testicular carcinoma?

OBJECTIVE: To correlate the number of tumour-infiltrating T lymphocytes (TILs) with the extent of apoptosis in testicular germ cell tumours, as TILs are considered to be a favourable prognostic factor of human testicular tumours, especially of seminomas, but the mechanism by which TIL contribute to an improved outcome is unclear. MATERIALS AND METHODS: Tissue samples from 47 patients with nonseminomatous germ cell tumour (NSGCT) and 15 with seminomatous GCT were investigated immunohistochemically for lymphocyte infiltration and apoptosis. The apoptotic index (AI) was assessed in various categories (DNA condensation and fragmentation) using in-situ end-labelling to identify typical apoptotic DNA strand breaks, and nuclear staining to identify typical apoptotic morphology. RESULTS: In seminomatous GCT there was no correlation between the number of TILs and any AI. In NSGCT there was only a relationship between lymphoid infiltration and those AIs showing morphological criteria of apoptosis in a small subgroup of NSGCT, i.e. metastasized embryonal cell carcinomas. Only 1.2% (AI, chromatin condensation) and 0.8% (AI, fragmentation and condensation) of all tumour cells showed these features of apoptosis. The overall AI in NSGCT was 7.9%. CONCLUSIONS: TILs do not seem to induce apoptosis in testicular tumours. Embryonal cell carcinomas might be susceptible to lymphocyte attack, resulting in apoptosis of the tumour cell. The mechanisms of interaction between lymphocytes and testis tumour cells need further investigation.

Endoreduplication in conjunction with tumor progression in an aneuploid laryngeal squamous cell carcinoma.

We report the case of a 58-year-old man who presented with a squamous cell carcinoma pT1a G2 of the left vocal cord. Six months after histologically verified complete resection, the patient experienced an endolaryngeal and extralaryngeal local recurrence pT4 pN2b G2. We applied DNA flow cytometry (FCM) and comparative genomic hybridization (CGH) on both primary and recurrent tumor. The primary tumor and the endolaryngeal compartment of the relapse was an aneuploid cell clone with a FCM DNA index of 1.42 and 1.44, respectively. The extralaryngeal compartment showed a shift featuring a DNA index of 2.78. In the primary tumor and in both compartments of the recurrence there was an identical pattern of complex chromosomal imbalances as detected in CGH (CGH karyotype: rev ish enh [8q24.2-q24.3, 10q26.1-q26.3, 11q24-q25, 12q24.2-q23.33,X], dim [4q, 13q14.3-q31], amp[1p36.1-p36.2]). Hence, the recurrence was not associated with further gains and losses of chromosomal material. However, in the anterior part of the recurrence, the aneuploid tumor cell genome had completely doubled, obviously due to endoreduplication. Immunohistochemical analysis of several cell-cycle regulators revealed altered expression of checkpoint proteins, pointing to a complex disturbance in cell-cycle regulation.

Cell proliferation and p27Kip1 expression in endophytic schneiderian papillomas.

OBJECTIVE: To clarify epithelial cell proliferation and p27Kip1 expression along the stepwise histological changes from endophytic schneiderian papillomas to associated carcinomas. STUDY DESIGN: Retrospective investigation involved surgical specimens from 58 patients. METHODS: Immunohistochemical assessment involved the nuclear Ki67 antigen expressed in proliferating cells. Further, the cyclin-dependent kinase (cdk) inhibitor p27Kip1 was assessed. Binding of p27Kip1 to the cyclin E-cdk2 complex inhibits this kinase, which results in cell cycle arrest. The expression rates of both proteins were compared between nonpapillomatous nasal mucosa, endophytic schneiderian papillomas, carcinoma in situ, and invasive squamous cell carcinomas. Statistics involved the Wilcoxon and Mann-Whitney u tests. Significance was set at P <.05. RESULTS: Comparable cell proliferation rates were observed between non-papillomatous nasal mucosa and cylindrical cell papillomas. Significant increases in cell proliferation were found along the stepwise series of histological changes involving non-papillomatous nasal mucosa, columnar epithelium in inverted papillomas, transitional and squamous metaplasia in inverted papillomas, and dysplastic inverted papillomas (P <.05, respectively). A tendency toward increased cell proliferation in carcinoma in situ compared with dysplastic inverted papillomas was present; however, this was not statistically significant. The expression rates of p27Kip1 were comparable between non-papillomatous nasal mucosa and all histological subtypes within nondysplastic endophytic schneiderian papillomas. Significantly reduced p27Kip1 expression was found in surface cells in dysplastic compared with non-dysplastic inverted papillomas, as well as in the total number of cells in carcinoma in situ compared with dysplastic inverted papillomas (P <.05, respectively). CONCLUSIONS: Inverted papillomas but not cylindrical cell papillomas show increased cell proliferation compared with nonpapillomatous nasal mucosa. Stepwise increases in cell proliferation accompany the consecutive histological changes within inverted papillomas. Among them, increased cell proliferation along with the development of dysplasia and carcinoma in situ is associated with reduced p27Kip1 expression.