MCM3 proliferative index is worthier over Ki-67 in the characterization of salivary gland tumors.

BACKGROUND: Salivary gland tumors bear uncanny characteristics of being different based on their morphological aspects rather than the presence of clear demarcation. This ambiguity in the spectrum from benign to malignant salivary gland neoplasms while categorizing the neoplasm is having inherent pitfalls. The present study was, therefore, designed to characterize benign and malignant salivary gland tumors based on their proliferative indices. MATERIALS AND METHOD: Study samples comprised of 97 cases of histopathologically confirmed benign and malignant salivary gland tumors. The cases were immunohistochemically assessed for MCM3 and Ki-67 expressions and the molecular characterization was performed based on the findings. RESULTS: The majority of benign and malignant salivary gland tumors were from the parotid gland, (51.2%) and (42.4%), respectively. Overall mean labeling index of MCM3 was higher i.e., (5.60 ± 3.99) in comparison to Ki-67 i.e., (2.82 ± 3.14) with P = 0.05 using paired t-test. Besides, malignant salivary gland neoplasms represented a higher mean score of MCM3 and Ki-67 than benign neoplasms. CONCLUSION: The requirement of a novel marker has led to the use of MCM3 which has a characteristic role in the entire spectrum of the cell cycle. The present study highlighted the extrapolation of MCM3 over Ki-67 for diagnosis and for true characterization of biologic behavior of salivary gland pathologies which may, in turn, influence the treatment modality employed for such lesions.

TORC1 signaling regulates DNA replication via DNA replication protein levels.

Accurate DNA replication is at the heart of faithful genome transmission in dividing cells. DNA replication is strictly controlled by various factors. However, how environmental stresses such as nutrient starvation impact on these factors and DNA replication is largely unknown. Here we show that DNA replication is regulated by target of rapamycin complex 1 (TORC1) protein kinase, which is a central regulator of cell growth and proliferation in response to nutrients. TORC1 inactivation reduced the levels of various proteins critical for DNA replication initiation, such as Mcm3, Orc3, Cdt1, and Sld2, and retarded DNA replication. TORC1 inactivation promoted proteasome-mediated Mcm3 degradation. Skp1-Cullin-F-box (SCF)-Grr1 and PEST motif mediated Mcm3 degradation. TORC1-downstream factors PP2A-Cdc55 protein phosphatase and protein kinase A regulated Mcm3 degradation. This study showed that TORC1 signaling modulates DNA replication to coordinate cell growth and genome replication in response to nutrient availability.

Expression of p53 and selected proliferative markers (Ki-67, MCM3, PCNA, and topoisomerase IIα) in borderline ovarian tumors: Correlation with clinicopathological features.

BACKGROUND: The expression of p53 has been studied not only in primary human ovarian carcinomas, but also in borderline ovarian tumors, however, the results were discordant. Expression patterns of proteins involved in cell proliferation and apoptosis have been investigated in various human neoplasms, including female genital tract neoplasms. OBJECTIVE: The aim of this investigation was to assess the staining pattern and immunolocalization of p53 and selected proliferative markers (Ki-67, MCM3, PCNA, and topoisomerase IIα) in borderline ovarian tumors (BOTs). DESIGN: The study group consisted of 42 women who underwent pelvic surgery between 2006-2015. The median patients' age was 46 years. The immunoperoxidase technique was employed using antibodies against p53, Ki-67, MCM3, PCNA, and topoisomerase IIα. RESULTS: For p53, nuclear expression was observed in BOTs, however, cytoplasmatic immunoreactivity was also detected. Altogether, 25 (60%) tumors demonstrated positive p53 immunostaining, including overexpression found in 6 (14%). There were no significant differences in p53 expression between subgroups of clinicopathological variables. Immunoexpression of Ki-67, MCM3, PCNA, and topoisomerase IIα was nuclear. Ki-67 expression was positive in 12 (29%) cases and there was a trend towards a relationship between patients' age and Ki-67 staining (P=0.08). Interestingly, a significantly higher Ki-67 expression was found in tumors of ≥10 cm in diameter compared to smaller tumors (P=0.008). MCM3 expression was detected in 38 (90%) tumors, and PCNA expression in 28 (67%), yet none of clinicopathological factors was related to them. Topoisomerase IIα expression was present in 14 (33%) cases and, interestingly, its significantly higher expression was observed in BOTs of ≥10 cm in diameter compared to smaller tumors (P=0.008). Moreover, Spearman's correlation revealed highly significant positive associations between Ki-67 and topoisomerase IIα (R=0.403, P=0.008) and Ki-67 and MCM3 (R=0.469, P=0.001). CONCLUSIONS: We report a high positive immunostaining rate for p53, suggesting a role of TP53 alterations in the development of BOTs in humans. The new finding of higher topoisomerase IIα immunostaining positivity in BOTs of ≥10 cm may be clinically relevant and requires further studies on larger patient groups.

A case of intraparotid schwannoma in a juvenile: Clinical, pathological, ultrastructural, and immunohistopathological study, including an examination of Ki-67 and MCM-3 expressions.

Pleomorphic adenoma, the most common benign nonvascular tumor of the parotid gland in juveniles, should be differentiated from other extremely rare tumors, including schwannoma. In this article, we present a rare case of an intraparotid schwannoma in a juvenile, along with the patient history, a description of pathological features, and the results of ultrastructural and immunohistochemical examination. The respective labeling indexes of Ki-67 and MCM-3, i.e., the mean proportions of positive tumor cells out of 1000 tumoral cells counted in 10 microscopic fields at ×400 magnification, given as a percentage, were found to be 0.82% and 0.4%, respectively.

Comparison between immunohistochemical expression of Ki-67 and MCM-3 in major salivary gland epithelial tumors in children and adolescents. Preliminary study.

While Ki-67 expression is frequently used as an indicator of tumor cell proliferation, alternative markers have also been proposed. Possible alternative indicators of proliferation are the minichromosome maintenance (MCM) proteins, whose levels are inversely associated with tumor cell differentiation. The aim of this preliminary study was to compare the levels of Ki-67 and MCM-3 expression in major salivary gland epithelial tumors in all children and adolescents who underwent surgery in our department in the years 2009-2014. The histopathological diagnosis of the subjects was reviewed, as well as the expression of Ki-67 and MCM-3 in post-op specimens of the tumors. The normality of data was checked with the Shapiro-Wilk test. The t test for independent variables or the U test was used as appropriate to determine statistically significant differences in the expression of Ki-67 and MCM-3. Five cases of pleomorphic adenoma, one of myoepithelioma, one of basal cell adenoma and one of mucoepidermoid carcinoma were identified. Significantly greater MCM-3 than Ki-67 expression was observed in every case. The results of our preliminary study emphasize the need for future research on MCM-3 as a sensitive proliferation marker, providing an alternative to Ki-67, in cases of various major salivary gland epithelial tumors in children and adolescents.

MCM3 could be a better marker than Ki-67 for evaluation of dysplastic oral lesions: an immunohistochemical study.

BACKGROUND: The aim of this study was to identify the expression of MCM3, Ki-67 and p27 in normal mucosa, leucoplakia and oral squamous cell carcinoma (OSCC) and determine whether altered expression could serve as a prognostic marker of a malignant progression of dysplastic lesions. METHODS: The samples were collected from 37 patients with oral leucoplakia (13 with mild dysplasia - MLD, 12 with moderate dysplasia - MD and 12 with severe dysplasia - SD). Eleven samples of mouth floor mucocele (M) and 50 floor mouth and tongue samples OSCC of untreated patients were included in this study. Immunohistochemical expression of MCM3, Ki-67 and p27 of all the groups was analysed. Kruskal-Wallis and Dunn's test were used to determine differences among groups, and a Pearson's correlation test was used to evaluate the correlation between the proteins. RESULTS: Ki-67 expression was higher in OSCC than M (P < 0.001) and MLD (P < 0.01) groups, and there was a lower expression in M compared with MD and SD (P < 0.05). Regarding p27, its expression was lower in OSCC compared with M, MD and SD. MCM3 expression was lower in M compared with SD and OSCC (P < 0.001), and MLD showed a lower expression when compared SD (P < 0.01) and OSCC (P < 0.001). Moreover, a better correlation was observed between the proteins MCM3 and p27 than between Ki-67 and p27 proteins when all lesions were examined together. CONCLUSIONS: This study showed that MCM3 could be a better marker than Ki-67 for evaluation of dysplastic oral lesions.