Molecular Pathological Study Of Cyclin D1Expression And CCND1Gene Amplification In Invasion Lobular Carcinoma Of Breast

BACKGROUND:Cyclin D1is a family member of the cell cycle proteins, termed Cyclins. It plays a rate-limiting role in regulating the G1progression by governing the restriction point of Gl-to-S progression of the cell cycle, which ultimately restarts proliferation by inducing the transition from G0/G1to S-phase. Dysregulation of Cyclin D1contributes to the loss of normal cell cycle control during tumorigenesis.Studies have shown that Cyclin D1has a closer relationship with breast, because it is crucial for the development of certain tissues especially for breast. Cyclin D1-deficient mice displayed a marked reduction in acinar development accompanied by a failure to lactate during pregnancy. Further more, clinical studies have demonstracted that Cyclin D1is ofen overexpressed in the breast cancers, and accompanied with its gene amplified in a certain proportion. Most important, it has been confirmed that Cyclin D1overexpression may resulte in abnormal mammary cell proliferation including the development of mammary adenocarcinomas in transgenic mice. All together suggest that cyclin D1may play an important oncogenic role in breast cancer.Invasion lobular carcinoma (ILC) is the second most common histological type in the breast cancers, and represents5-15%of invasive carcinoma. Its pathogenesis is not clear. Due to its incidence is much lower than invasive ductal carcinoma (IDC), moreover, the tumor is composed of non-cohesive cells individually dispersed or arranged in Indian-file pattern in a fibrous stroma, which is not easy to extract or culture, so the related molecular biology research is less, and the understanding of the molecular pathology in ILC is insufficient.It is reported that Cyclin Dl is overexpression in about80%ILC. To examine whether the overexpression of Cyclin D1is due to its gene CCND1amplification, which may contribute to the pathogenesis of ILC, we designed this study:to detect the Cyclin D1expression and CCND1amplification by immunohistochemistry and fluorescence in situ hybridization (FISH) respectively on73cases of classic ILC, combining the clinical-pathological data and follow-up to investigate the clinical and molecular pathological values in ILC.ResultOur study showed that CCND1amplified in26%(19/73) cases, and Cyclin D1positive expressed on nucleus in94.5%(69/73) cases. Among them, there were53.4%(39/60) cases showing strong diffuse staining (3+,6-7points), and32.9%(24/69) cases showing moderately positive staining (2+,4-5points), and8.2%(6/69) cases showing weak positive staining (1+,2-3points); Only5.5%(4/73) cases showed negative results (0-1points). The high-expression of Cyclin D1was in83.6%cases, which presented a moderate to strong degree of positive staining, and had a statistical correlation with the CCND1amplification. This suggested that CCND1amplification can induce to the high-expression of Cyclin D1in ILC. But at the same time, a new problem presented here that a difference in incidence between the CCND1amplification and Cyclin D1high-expression. This suggested that CCND1amplification was not the only reason for the high-expression of Cyclin D1, and there may also be some other mechanisms which can lead to its high expression. Reviewed literatures, we found that some related mechanisms hypothesis in breast cancer but not in the ILC had been reported with IDC as the most objectives, and they were related to transcription activation, increased protein translation, diminished degradation process and so on. Among them, the most consistented with ILC was the crossover interaction between estrogen, ER and Cyclin D1. Although this mechanism is not fully elucidated, it is very likely in resulting high expression of Cyclin D1in promoting the development of ILC.Then, we performed the correlation analysis individually between the CCND1amplification or Cyclin D1high-expression and the clinical-pathological features including age (>50years), maximum tumor diameter (>2cm), lymph node metastasis, involvement of papillary interstitial tissue and the large duct beneath it, single/multiple tumors, clinical stage:early period (I stage)/advanced period (Ⅱ、Ⅲ、Ⅳ stage), existence of estrogen and progesterone receptors, Her-2overexpression and p53mutation, as well as prognosis. Finaly we only found a statistically significant correlation between high-expression of Cyclin Dland ER positive (P<0.05). This further strengthened the above hypothesis that ER could play a cardinal role in resulting high expression of Cyclin D1in ILC.Conclusion Our study displays the status of the CCND1amplification and the Cyclin D1expression in ILC, and confirms the statistical correlation between high-expression of Cyclin D1and CCND1amplification as well as the positivity of ER. These results may contribute to the pathogenesis of ILC. However, neither amplification nor high-expression of Cyclin D1does seem to have clinical or prognostic value in ILC, although this needs to be confirmed by studing more ILC cases and further follow-up.