Comparative Expression Analysis of TP53 Tumor Suppressor and MDM2 Oncogene in Colorectal Adenocarcinoma.

Background/Aim: The tumor protein 53 (TP53) tumor suppressor protein (17p13.1) acts as a significant regulator for the cell cycle normal function. The gene is frequently mutated in colorectal adenocarcinoma (CRC) patients and is associated to poor prognosis and low response rates to chemo-targeted therapy. Our purpose was to correlate TP53 expression with Mouse Double Minute 2 Homolog (MDM2), a proto-oncogene (12q14.3) and a major negative regulator in the TP53-MDM2 auto-regulatory pathway. Materials and Methods: A total of forty (n=40) colorectal adenocarcinoma (CRC) cases were included in this study. An immunohistochemistry-based assay was implemented by using anti-TP53 and anti-MDM2 antibodies in the corresponding tissue sections. Additionally, a digital image analysis assay was implemented for objectively measuring TP53/MDM2 immunostaining intensity levels. Results: TP53 protein overexpression was detected in 27/40 (67.5%), whereas MDM2 overexpression in 28/40 (70%) cases. Interestingly, in 21/40 (52.5%) cases, a combined TP53/MDM2 co-expression was detected, whereas in 6/40 (15%), a combined loss of expression was identified (overall co-expression: p=0.119). p53 overexpression was significantly correlated to grade of the examined cases (p=0.001), whereas MDM2 to stage and max diameter of the malignancies (p=0.001 and 0.024, respectively). Conclusion: TP53/MDM2 over expression is a frequent and significant genetic event in CRCs associated with an aggressive biological behavior, as a result of increased dedifferentiation grade and advanced stage/elevated tumor volume, respectively. MDM2 oncogene overactivation combined with mutated and overexpressed TP53 is observed in sub-groups of patients leading to specific gene/protein signatures - targets for personalized chemotherapeutic approaches.

P53/MDM2 Complex-Based Targeted Strategies in Colon Adenocarcinoma.

In the current molecular review, we describe the mechanisms of TP53/MDM2 deregulation and their impact on the colon adenocarcinoma molecular substrate and phenotype. Among the genes that are critically altered in carcinogenesis, the TP53 tumor suppressor gene is of major importance. The TP53 gene (gene locus: 17p13.1) regulates the cell cycle by controlling the G1/S and G2/M checkpoints securing the normal sequence of cell cycle phases. Furthermore, it is involved in apoptosis programmed cell death. The gene is mutated or epigenetically altered in all epithelial malignancies, including colon adenocarcinoma. Additionally, Mouse Double Minute 2 Homolog (MDM2), a proto-oncogene (12q14.3), acts as a major negative regulator for p53 expression in the p53-MDM2 auto-regulatory pathway. MDM2 binds directly to p53 and represses its transcriptional activity, promoting p53 degradation. CONCLUSION: In colon adenocarcinoma, MDM2 oncogene overexpression directly influences p53 oncoprotein expression levels.

Reconstructing carcinoma of the lip commissure and buccal mucosa: an oncosurgical alternative approach.

PURPOSE: To describe a new technique of surgical treatment of the lip commissure or buccal mucosa carcinomas, where we use local flaps (skin, buccal mucosa) of the sliding type. METHODS: According to the current technique, the ectomy ranges horizontally and in a cuneiform shape towards the side of the buccal cavity, and in the whole thickness of the layer (skin - mucosa), where the neoplastic focus is enclosed. RESULTS: The difference in our technique consists of the following: To the vertical bi-cuneiform part of the wound a horizontal cuneiform part (with the top showing upwards) is added, with extent and width analogous to those of the cancerous injury (tri-cuneiform ectomy). The width of the gap across its horizontal part is larger on the side of the mucosa (continuous line), compared to the one along the side of the skin (punctuated line), since the mucosa, as a more versatile tissue, can be sutured easily, in contrast to the buccal skin, which is of greater thickness and shows lack of versatility, so that it can be pulled on with difficulty in order to be sutured. The planning of the injury, according to our described technique, facilitates the broad ectomy of the intraoral injuries in the area of the lip commissure and the buccal mucosa, with immediate suture of the flaps (buccal and skin gap), and the occlusion of the wound by primary intention. CONCLUSIONS: Using this specific technique, in the cases of extended injuries infiltrating the skin or the subcutaneous tissue, the harming use of transposition (sliding or free) flaps is avoided.

Impact of Topoisomerases Complex Deregulation on Head and Neck Carcinoma Genomic Instability.

Head and neck carcinoma (HNC) comprises a variety of pathological entities. Among them, squamous cell carcinoma (SCC) is histo-pathologically prominent. Specific malignancies, such as nasopharyngeal carcinoma (NPC) arise also from the same anatomical region. In all of them, genomic instability (GI) is implicated not only in the early stages of epithelial malignant transformation, but also in the aggressiveness of the corresponding phenotypes. Among the molecules that are frequently deregulated in solid malignancies including HNCs, topoisomerases (Topo) are of increased significance due to their involvement in DNA topological, structural, and functional stability. The main members are Topo I (20q11), Topo II alpha (17q21) and Topo IIb (3p24). In the current article, we describe the mechanisms of Topo I and Topo IIa deregulation leading to GI in a variety of HNCs. Furthermore, novel data regarding the corresponding targeted therapeutic strategies are presented.

Impact of K-Ras Over-expression in Laryngeal Squamous Cell Carcinoma.

BACKGROUND/AIM: Oncogene up-regulation combined with suppressor gene down-regulation is a crucial genetic combination that promotes cell neoplastic phenotype and progressively malignant transformation in solid malignancies, including laryngeal squamous cell carcinoma (LSCC). Among oncogenes, the Kirsten ras oncogene homolog (K-Ras) is involved in LSCC onset and progression. PATIENTS AND METHODS: Sixty (n=60) primary LSCC tissue sections were analyzed by immunohistochemistry (IHC). Digital image analysis (DIA) was also implemented for measuring K-Ras protein expression levels. RESULTS: High K-Ras protein expression levels were observed in 20/60 (33.3%) LSCC tissue sections, whereas the rest of the cases (n=40; 66.7%) demonstrated low expression. Overall K-Ras expression was borderline significantly associated to the grade of the examined malignancies (p=0.048), whereas no other strong statistical correlations were identified. A progressive K-Ras overexpression was observed in all grades of the examined cases. CONCLUSION: K-Ras over expression is correlated to a progressive dedifferentiation in LSCC.

Micro-RNAs signatures in papillary thyroid carcinoma.

Among biomarkers that should be useful for a molecular discrimination of patients regarding treatment strategies and prognosis in solid malignancies, novel micro-RNAs (miRs) are under investigation. Quite recently, miRs are considered very promising and significant genetic markers for categorizing patients by their molecular characteristics, as well as extending their complicated genetic signatures. miRs are short, non-coding RNAs consisting of 20-25 nucleotides located at intra- or inter-gene regions. Functional miRs mediate a positive regulation of posttranscriptional gene silencing. Their deregulation in cancer cells due to genetic (e.g., mutations, translocations), epigenetic (e.g., DNA hyper-methylation of tumor suppressor genes, extensive genomic DNA hypo-methylation, aberrant histone modification patterns) and transcriptional alterations lead to a loss of miRs-mediated repression of target mRNA. Interestingly, a biphasic role of miRs in cancers of different histogenetic origin has been confirmed. In some of them, their upregulation is correlated with an increased oncogenic activity, whereas in others, the same miR type acts as a suppressor agent. Thyroid carcinoma comprises different histological subtypes, such as papillary thyroid carcinoma (PTC), follicular thyroid carcinoma (FTC), anaplastic thyroid cancer (ATC), and medullary thyroid carcinoma. In the current molecular review, we explored the role of a specific fraction of miRs in PTC subtype by categorizing them according to their up- or down-regulation status.

ki-67 and Topoisomerase IIa proliferation markers in colon adenocarcinoma.

Aberrant cell proliferation is a major cause in the development and progression of carcinogenic process. Epithelia characterized by increased mitotic rates accumulate easily gross numerical and structural chromosomes (polysomy/aneuploidy) and specific gene (deletions, amplifications, point mutations, translocations) deregulations that lead to their progressive neoplastic and finally malignant transformation. Molecules that are critical for evaluating the proliferation status of the corresponding tissues include mainly ki-67 (cytogenetic band: 10q26.2), and also Topoisomerase IIa/Topo IIa (cytogenetic band: 17q21.2). Both of them demonstrate different expression patterns in every cell cycle phase and their estimated expression as Nuclear Labeling Index (NLI) is a very useful tool for assessing the aggressiveness of the examined pre- and malignant tissues. In fact, ki-67 expression increases as a cell progresses through the cell cycle, with highest expression being seen in G2/M phase cell, whereas Topo IIa is expressed in proliferating cells in the late S phase with a peak in G2-M phases. Concerning colon adenocarcinoma, high expression levels of them seem to correlate with advanced disease and also with modified response rates to specific chemotherapeutic agents, such as doxorubicin, an inhibitor of Topo IIa. In the current molecular review we explored the role of these proliferative markers in colon adenocarcinoma and their influence in the tumor biological behavior.

Chromogenic in situ hybridization analysis of EGFR gene copies in colon adenocarcinoma based on intra-operative imprints and tissue microarrays.

BACKGROUND: Although Epidermal Growth Factor Receptor (EGFR) over expression is a frequent event in colon adenocarcinoma (CA), identification of EGFR gene deregulation mechanisms--combined to k-ras mutations--remains the basic criterion for rational application of anti-EGFR targeted therapeutic strategies. AIM: To detect EGFR gene numerical alterations in CA based on a combination of intra-operative imprints and the corresponding tissue microarrays. METHODS: 60 paraffin embedded primary CAs were cored at 1.5 mm diameter and transferred to the final microarray block. Chromogenic in situ hybridization (CISH) was performed using EGFR gene and chromosome 7 centromeric probes in the tissue microarray and also in the corresponding intra-operative imprints. RESULTS: CISH analysis detected 4/60 (6.6%) EGFR gene amplified cases, whereas chromosome 7 aneuploidy was identified in 11/60 (18.3%) cases. Significant association was established by correlating stage to chromosome 7 (p=0.024). A high value of concordance (kappa=1) was observed comparing overall gene status based on the tissue cores and the corresponding imprints, whereas EGFR/CEN 7 copies were more numerous in imprints than in tissue microarrays (p=0.03). CONCLUSIONS: Intra-operative imprint cytology provides accurate and fast results in detecting EGFR gene/chromosome 7 centromeric signals by CISH due to the nuclear integrity and monolayer formation of the examined cells. Based on this molecular analysis, gastroenterologists and oncologists can handle those patients in a rational way regarding targeted therapies. Furthermore, chromosome 7 aneuploidy is associated with a more advanced stage in CA.