Cytoplasmic and nuclear interaction between Rb family proteins and PAI-2: a physiological crosstalk in human corneal and conjunctival epithelial cells.

Extracellular plasminogen activator inhibitor type-2 (PAI-2) is a potent inhibitor of urokinase-type plasminogen activator (u-PA) and also acts as a multifunctional protein. However, the biological activity of intracellular PAI-2, as well as its intracellular targets, until now remain an enigma. Here, we show that pRb2/p130 and Rb1/p105, but not p107, interact with PAI-2 in both the cytoplasm and nucleus of normal primary human corneal and conjunctival epithelial cells. We provided the first in vivo evidence that a specific fragment of the PAI-2 promoter is bound simultaneously by pRb2/ p130, PAI-2, E2F5, histone deacetylase 1 (HDAC1), DNA methyltransferase 1 (DNMT1), and histone methyltransferase (SUV39H1), in normal primary human corneal epithelial cells, and by pRb2/p130, PAI-2, E2F5, HDAC1, and DNMT1, in normal primary human conjunctiva epithelial cells. Our results strongly indicate a physiological interaction between pRb family members and PAI-2, suggesting the hypothesis that pRb2/p130 and PAI-2 may cooperate in modulating PAI-2 gene expression by chromatin remodeling, in normal corneal and conjunctival cells.

Plasminogen activator inhibitor type 2 (PAI-2) is present in normal human conjunctiva.

The purpose was to characterize plasminogen activator inhibitor type 2 (PAI-2) expression in normal human conjunctiva in vivo and in vitro. PAI-2 antigen was assayed by immunostaining and immunoblotting of extracts from normal human conjunctival epithelial lysates and conditioned media (CM) of cultured human conjunctival keratinocytes. Immunostaining of normal human conjunctival epithelia revealed that PAI-2 was found consistently in the superficial keratinocytes and, in some biopsies, also in the lower keratinocyte layers. In all cases, PAI-2 was concentrated around the cell periphery. In extracts of conjunctival epithelia and cultured conjunctival keratinocytes, PAI-2 had an apparent molecular weight of 45 kDa, consistent with the non-glycosylated form. The majority of PAI-2, approximately 90%, was cell associated, however, a small percentage of PAI-2 was released into the CM in a linear manner with time. PAI-2 in the conditioned medium had a higher molecular weight, consistent with a glycosylated form. Conjunctival PAI-2 was active, as shown by its ability to complex with a target enzyme, urokinase plasminogen activator (uPA). Although PAI-2 was detectable both in monolayer (i.e., relatively undifferentiated) conjunctival keratinocyte cultures as well as in stratified (i.e., more differentiated) cultures, steady state levels of PAI-2 were greater in the latter. PAI-2 is constitutively expressed by normal human conjunctival epithelial cells. The expression of PAI-2 throughout all epithelial layers in some biopsies of conjunctiva in vivo contrasts with the previously established distribution of PAI-2 in corneal epithelia, where it is present exclusively in the most superficial (i.e. most highly differentiated) cells. The role of PAI-2 in either tissue is unclear. However, we speculate that its distinct distribution in conjunctival versus corneal epithelia underscores inherent differences between these tissues, and may reflect specific functions of this proteinase inhibitor in both conjunctival and corneal epithelial cells.

Differential expression of the retinoblastoma gene family members in choroidal melanoma: prognostic significance.

We evaluated 55 samples of choroidal melanoma managed by enucleation. Knowing that the immunohistochemical expression of the retinoblastoma gene family members Rb/p105, p107, and pRb2/p130 was inversely correlated with the degree of malignancy in at least some histological types, we investigated the expression of these three proteins in choroidal melanoma. We focused on the relationship between patient survival and the immunohistochemical detection of the retinoblastoma proteins. No correlation with clinical outcome was found for Rb/p105 and p107. However, we found pRb2/p130 to be an independent prognostic factor correlating positively or directly with patient survival times and indirectly or inversely with the degree of malignancy. Demonstration of the prognostic value of the immunohistochemical expression of pRb2/p130 is of significance, even if additional studies are required to confirm these data and to compare the prognostic value of pRb2/p130 immunodetection to that of other recently proposed markers, such as p53.

Orbital floor implant migration across the ethmoidal sinuses and nasal septum.

PURPOSE: To report an unusual case of orbital floor implant migration across the ethmoidal sinuses and nasal septum. METHOD: Case report. A 61-year-old woman with a history of right orbital floor fracture repair 25 years earlier is described. RESULTS: The patient presented with sinus congestion and difficulty breathing through the right nostril. Computed tomographic scan disclosed medial migration of the right orbital floor implant across the ethmoidal sinuses and nasal septum. The patient underwent transorbital and transnasal endoscopic surgery with removal of the implant. CONCLUSIONS: When an alloplastic orbital floor implant is required, size and fixation of the implant are important. Late paranasal sinus or nasal airway problems may be sequelae, and the possibility of implant migration should be considered.

Prognostic factors for survival after enucleation for choroidal melanoma.

To evaluate the prognostic value of DNA content-ploidy, agoraphilic nucleolar organizing regions (AgNORs) and proliferating cell nuclear antigen (PCNA) for survival among patients with choroidal melanoma choroidal melanomas managed by enucleation in 55 patients with a follow-up of 5 years were studied. AgNor counts were evaluated by two examiners after sections were specifically processed. Immunohistochemistry was performed to evaluate PCNA expression. Kaplan-Meier estimation of survival curves, the log-rank test, and Cox regression analysis were used to compare survival according to the above mentioned factors. Five years after enucleation 62% of patients had died. Patients with spindle cell type melanomas had the best and those with epithelioid cell type had the worst survival (p=0.004). Patients with small tumors had better survival than those with medium or large tumors (p=0.02). Patients having tumors with aneuploid nuclear DNA content had worse survival than those having tumors with diploid DNA content (p=0.004). A high PCNA level correlated with lower survival rates (p=0.02). Patients having a high AgNor count had a worse survival than those with lower counts (p=0.02). DNA content, PCNA level, and AgNOR count each showed a clinically significant influence on patient survival. However, each of these new evaluated prognostic factors was strongly related to one or both of the classic prognostic factors. It is therefore difficult to separate the effects of the two categories of prognostic factors. Results of the Cox regression analysis suggested that these newer evaluated prognostic factors provided little additional information about patient prognosis.