Comparative study of the immunohistochemical expression of tissue inhibitors of metalloproteinases 1 and 2 between clearly invasive carcinomas and "in situ" trophoblast invasion.

Tissue inhibitors of metalloproteinases (TIMPs) play an important role in extracellular matrix homeostasis by regulating MMP activity. Although they were initially considered inhibitors of tumor growth and metastasis, recently their role in cancer progression has been controversial. The aim of our study was to compare the immunohistochemical expression of TIMP1 and TIMP2 between an uncontrollably invasive phenomenon (cancer) and an "in situ" process (trophoblast invasion) in an effort to assess any differential role of these molecules between these two distinct phenomena and therefore to understand better their contribution in cancer invasion and migration. We performed an immunohistochemical analysis of 50 carcinomas (colorectal, gastric, breast, pulmonary, and renal) and 40 first trimester gestations. The marker expression was evaluated semiquantitatively, separately in cancer parenchymal and trophoblastic cells as well as in malignant stromal and decidual cells, according to a percentage scale (0, <10, 10-50, and >50%) and according to staining intensity (0, +, ++, and +++). Our results showed that there was no statistically significant difference in TIMP1 expression between cancer parenchymal cells and trophoblastic cells. On the other hand, TIMP1 was expressed more often in decidual cells than in cancer stromal cells. Immunostaining for TIMP2 was more extensive and intense both in trophoblastic and decidual cells than in cancer parenchymal and stromal cells, respectively. The reduced expression of TIMP2 in metastatic carcinomas by comparison with non-metastatic gestation specimens underlines its importance in cancer invasion and migration. On the other hand, TIMP1 was more expressed in decidua than cancer stroma, but at the same time showed no statistically significant difference between cancer parenchyma and trophoblasts, highlighting its multifunctional activity in cancer progression.

Distinct expression patterns of the transcription factor E2F-1 in relation to tumour growth parameters in common human carcinomas.

E2F-1 is a pivotal transcription factor that integrates signals from a variety of G1/S phase regulators and modulates diverse cellular functions, such as DNA synthesis, repair, mitosis, and apoptosis. Its role in cellular proliferation and apoptosis, as depicted from experimental models and limited reports in human malignancies, remains a matter of debate. Recently, in non-small cell lung cancer, it was observed that E2F-1 overexpression was associated with tumour growth, implying an 'oncogenic' effect. To clarify further the role of E2F-1 in carcinogenesis, the investigation was expanded in four of the most common human malignancies by examining its expression status and putative impact on tumour kinetics. These issues were addressed by immunohistochemical and molecular means in 52 breast carcinomas, 42 prostate adenocarcinomas, 58 colon adenocarcinomas, and 77 superficial bladder transitional cell carcinomas (TCCs). The following results were found: (i). in breast carcinomas, E2F-1 expression correlated with proliferation (p < 0.001) and growth index (p = 0.001); (ii). in prostate adenocarcinomas, absence of E2F-1 was noted, in contrast to its expression in normal and hyperplastic glands; (iii). in colon adenocarcinomas, E2F-1 expression was inversely related to growth index (p = 0.001), being expressed in lesions with increased apoptosis (p = 0.001) and low proliferation (p < 0.001); and (iv) in superficial TCCs, E2F-1 expression correlated with proliferation (p = 0.002). Taken together, these results suggest that E2F-1 has a growth-promoting effect in breast carcinomas and superficial TCC, whereas the opposite seems to be the case for colon and prostate cancer. To interpret the above findings, the status of the pRb and p53 tumour suppressor pathways, which are known to affect E2F-1 activity, was further investigated. The results suggest that the actions of E2F-1 are mainly dependent on the functionality of these pathways. Nevertheless, the data also imply that p53-independent pathways may play a nodal role in the function of E2F-1 in colon cancer.