Mounir Trimeche

Previous investigations have indicated that CD10 is associated with biological aggressivity in human cancers, but the use of this marker for diagnosis and prognosis is more complex. The aim of this study was to evaluate the expression of CD10 in breast cancer and its association with the clinicopathological features. In addition, we investigated whether a relationship exists between CD10 expression and cancer stem cells. CD10 expression was examined by the immunohistochemistry in a series of 133 invasive breast carcinoma cases. Results were correlated to several clinicopathological parameters. Cancer stem cell phenotype was assessed by the immunohistochemical analysis of CD44 and ALDH1. Significant CD10 expression was found in the fusiform stromal cells in 19.5% of the cases and in the neoplastic cells in 7% of the cases. The stromal CD10 positivity was more frequently found in tumors with lymph node metastasis (p = 0.01) and a high histological grade (p = 0.01). However, CD10 expression by the neoplastic cells correlates with a high histological grade (p = 0.03) and the absence of estrogen (p = 0.002) as well as progesterone (p = 0.001) receptor expression. We also found that CD10 expression by the stromal cells, but not by the neoplastic cells, correlates significantly with the expression of cancer stem cell markers (CD44+/ALDH1+) (p = 0.002). These findings support the role of the stromal CD10 expression in breast cancer progression and dissemination, and suggest a relationship with cancer stem cells.

We compared the features of the Epstein-Barr virus (EBV) and Hodgkin lymphoma (HL) association in Tunisia in two periods of time, 1991–2001 (111 cases) and 2002–2012 (122 cases). The investigation of the EBV status by EBER in situ hybridization showed a significant decrease in the prevalence of EBV-positive HL from 69.3 % for the period 1991–2001 to 40.1 % for the 2002–2012 period (p = 0.00001). EBV positivity has decreased in all age groups but was more pronounced among young patients, in the 15–24-year age group (46.1 vs 10.3 %, p = 0.003), in the 25–34-year age group (56.2 vs 25 %, p = 0.04), and among children (88.4 vs 59.2 %, p = 0.01). This decrease in EBV-positive HL over time contrasted with a remarkable increase in EBV-negative HL in young adults aged 15–34 years (51.2 vs 83 %; p = 0.001), especially among women (59.1 vs 91.2 %; p = 0.01). The decrease in EBV-positive HL over time concerns particularly the nodular sclerosis histological subtype (69.2 vs 31.6 %, p = 0.000001). These results indicate that the epidemiology of HL and its association with EBV are changing over time, with a trend toward a Western profile, and point toward the emergence of other environmental causative factors, especially among young women, which remain to be identified.

Hodgkin lymphoma (HL) is characterized by the presence of Hodgkin and Reed-Sternberg cells. Epstein-Barr virus (EBV) infection is thought to play an important role in the development of HL. Although epigenetic alterations, such as aberrant DNA methylation, are known to contribute to the pathogenesis of various malignancies, little is known about such alterations in HL and their putative relationships with EBV infection. We investigated promoter methylation patterns of seven tumor-associated genes in 53 primary HL cases using methylation-specific PCR (MS-PCR). Concomitantly, the EBV infection status was assessed using PCR, in situ hybridization and immunohistochemistry. The gene promoter hypermethylation frequencies observed were 77.3 % for P16, 58.5 % for RASSF1A, 50.9 % for CDH1, 45.3 % for DAPK, 43.4 % for GSTP1, 37.7 % for SHP1 and 24.3 % for MGMT. SHP1 gene promoter hypermethylation was more frequently observed in patients at extreme ages (i.e., ≤ 15 and >54 years) than in adult patients (p = 0.006) and in patients with B symptoms (p = 0.03). Interestingly, most of the analyzed gene promoters were more frequently hypermethylated in EBV-negative than in EBV-positive cases, in particular the DAPK gene promoter (58 % versus 27 %, p = 0.04). Furthermore, hypermethylation of multiple gene promoters (≥ 3) was encountered more frequently in females than in males (86 % versus 57 %, p = 0.04), whereas EBV-positive cases were more common among males than females (55 % versus 30 %, p = 0.02). Our results indicate that epigenetic changes frequently occur in both EBV-positive and EBV-negative HL. The rates of these changes were found to vary according to clinico-pathological parameters. These observations probably reflect the multitude of factors involved in HL development and the complexity of their interactions with genetic and/or hormonal factors.

Deregulation of the microRNA miR124a by DNA methylation has been implicated in various malignancies, but no study reported its methylation status in Hodgkin lymphoma (HL). We evaluated the methylation of the three loci encoding for miR124a using methylation-specific PCR in 64 HL patients and 15 reactive lymph nodes obtained from patients with nonmalignant diseases. Results were correlated with clinicopathological parameters. Methylation rates of miR124a-1, miR124a-2, and miR124a-3 in HL were 17, 50, and 28 %, respectively. None of the nontumoral samples showed aberrant hypermethylation in any of the miR tested. In HL cases, we found that miR124a-1 methylation correlates with high-risk International Prognostic Score (IPS) (score >3, p = 0.04) and that miR124a-2 methylation was more frequent in children (82.3 %, p = 0.006) and men (63.9 %, p = 0.01). Methylation of miR124a-3 was associated with advanced Ann-Arbor stages (p = 0.007). The survival analysis showed that methylation of at least one of the miR124a genes was associated with shortened event-free survival in univariate (p = 0.03) and multivariate (p = 0.02) analyses. These results suggest that miR124a methylation is associated with aggressive HL disease and may be an interesting factor for predicting treatment response.

Aberrant DNA methylation on CpG islands is one of the most consistent epigenetic changes in human cancers, and the process of methylation is catalyzed by the DNA methyltransferases DNMT1, DNMT3a, and DNMT3b. Recent reports demonstrate that deregulation of miR-124a, one of the frequently methylated microRNAs in human cancers, is related to carcinogenesis. The aim of this study was to evaluate the frequencies of methylation of the three genomic loci encoding the miR-124a in primary breast cancers and to investigate their relationships with the clinicopathological characteristics of the tumors and with the expression levels of DNMT1, DNMT3a, and DNMT3b. The methylation status of the three genomic loci encoding the miR-124a (miR-124a-1, miR-124a-2, and miR-124a-3) was analyzed in fresh-frozen tumor samples using methylation-specific PCR in a large series of invasive breast ductal carcinomas (n = 60). Results were correlated to several clinicopathological characteristics of the tumors and to the expression levels of DNMT1, DNMT3a, and DNMT3b, determined by immunohistochemistry. Promoter hypermethylation of miR-124a-1, miR-124a-2, and miR-124a-3 was detected in 53.3, 70, and 36.7 % of cases, respectively. Methylation of miR-124a-2 correlated to patients with age higher than 45 years (P = 0.008) and to postmenopausal patients (P = 0.03), whereas methylation of miR-124a-3 correlated significantly to tumor size >20 mm (P = 0.03). Interestingly, simultaneous methylation of the three genes encoding miR-124a correlated significantly with the presence of lymph node metastasis (P = 0.01) and high mitotic score (P = 0.03). No significant correlation was found between promoter hypermethylation of miR-124a and expression of hormone receptors or HER2/neu. With regard to DNMT expression, no correlation was found between DNMT1 or DNMT3a expression and promoter methylation of any tested microRNA. However, DNMT3b overexpression correlates significantly with the hypermethylation of miR-124a-3 (P = 0.03). Our data indicates that miR-124a-1, miR-124a-2, and miR-124a-3 genes are frequently methylated in breast cancer and play a role in tumor growth and aggressivity.