Down-regulation of p27Kip1 expression is correlated with increased cell proliferation but not expression of p21waf1 and p53, and human papillomavirus infection in benign and malignant tumours of sinonasal regions

AIMS: Although p27Kip1(p27) is a cyclin-dependent kinase inhibitor and a contribution to tumorigenesis has been hypothesized, the possible role in tumours arising in the nasal and paranasal sinus regions is still unknown. METHODS AND RESULTS: Seventy-six sinonasal tumours, including 28 inverted papillomas (IPs) and 48 squamous cell carcinomas (SCCs), were immunohistochemically investigated, along with 46 exophytic papillomas (EPs) of upper respiratory tract and 34 samples of normal paranasal sinus epithelium. The results were also compared with expression of p21WAF1 (p21) and p53, cell proliferation assessed in terms of Ki67 labelling indices (LIs), and human papillomavirus (HPV) infection. The average p27 scores decreased from normal through to malignant lesions, while Ki67 LI scores showed a stepwise increase, the inverse correlation between scores for all categories being significant (r = - 0.639, P < 0. 0001). In the SCCs, p27 expression was significantly higher in keratinizing than nonkeratinizing type tumours (P < 0.05), while there was no association with p21 and p53 expression. Although HPV DNAs for type 16 and 18 were detected in two (7.4%) of 27 EPs, six (35.8%) of 28 IPs, and nine (28.1%) of 32 SCCs, no relation with p27 scores was evident. CONCLUSION: Loss of p27 expression correlates with increased cell proliferation in sinonasal tumours. Moreover, the expression appears to be associated with keratinization in SCCs of the paranasal sinus. These findings indicate that p27 expression may be a useful marker for the dysregulation of cell kinetics in these tumours.     

Expression of p21WAF1/CIP1 in colorectal adenomas and adenocarcinomas and its correlation with p53 protein expression

The expression of p53-Inducible cylln-dependent kinase Inhibitor, p21^WAF1/CIP1 in non-neopiastic mucosa, adenoma and adenocarclnoma of the colorectum was examined by immunohistochemistry and western bootting and Its relation with the expression of p53 protein was analyzed. Non-neoplastic epithelial cells at the surface area showing no proitferative activity expressed p21^WAF1/CIP1.The expression of p21^WAF1/CIP1 was lmmunohistochemlcally detected in 55% (206/377 of the adenomas and 66% (190/289) of the adenocarcinomas, respectively. The lncldence of strongly positive cases was significantly higher In the adenocarcinomas (27%) than In the adenomas (18%) ( P< .05). The incidence of cases wtth strong p21^WAF1/CIP1 expression was higher In stages 0,1 and 2 carcinomas than in stages 3 and 4 carcinomas ( P <0.05). A decrease in the incidence of cases with strong expression was detected in carclnomas Invading deeper than muscularis propria. The influence of strongly positive cases was signiflcantly lower in carcinomas with lymph node metastasis than those without metastasls ( P <0.05). The expression of p21 as well as p53 detected by western blotting was compatlble with the results of lmmunohistochemlstry in most cases examined. However, there was no significant correlatlon between the expression of p21^WAF1/CIP1 and the abnormal accumulation of p53. These findlngs overall suggest that: (i) the physiological expression of p21^WAF1/CIP1 may be associated with cellular senescence of colorectal mucosa; (ii) reduced expression of p21^WAF1/CIP1 participate in the progression of colorectal carcinoma; and (iii) p53-Independent paulway may be considerably Involved In the inductions of p21^WAF1/CIP1.     

JNK and p38 MAP kinases in CD4+ and CD8+ T cells

Summary: The c‐Jun aminoterminal kinase (JNK) and p38 mitogen‐activated protein (MAP) kinase signaling pathways have been associated with cell death, differentiation and proliferation. CD4⁺ and CD8⁺ T cells have different effector functions after antigen stimulation and control specific aspects of the immune response. The studies carried out in our group indicate that the role of JNK and p38 MAP kinases in CD4⁺ T cells is different from their role in CD8⁺ T cells. Moreover, these two pathways are not redundant in either T cell population. We have also shown that p38 MAP kinase regulates early stages of T cell development in the thymus. It is therefore important to consider the specific function of these kinases in each T cell population when pharmacological inhibitors of JNK and p38 MAP kinases are used for therapeutic purposes to control the immune response.     

Selectivity and interactions of Ba2+ and Cs+ with wild-type and mutant TASK1 K+ channels expressed in Xenopus oocytes

The acid-sensitive K⁺ channel, TASK1 is a member of the K⁺-selective tandem-pore domain (K2P) channel family. Like many of the K2P channels, TASK1 is relatively insensitive to conventional channel blockers such as Ba²⁺. In this paper we report the impact of mutating the pore-neighbouring histidine residues, which are involved in pH sensing, on the sensitivity to blockade by Ba²⁺ and Cs⁺; additionally we compare the selectivity of these channels to extracellular K⁺, Na⁺ and Rb⁺. H98D and H98N mutants showed reduced selectivity for K⁺ over both Na⁺ and Rb⁺, and significant permeation of Rb⁺. This enhanced permeability must reflect changes in the structure or flexibility of the selectivity filter. Blockade by Ba²⁺ and Cs⁺ was voltage-dependent, indicating that both ions block within the pore. In 100 m m K⁺, the K _D at 0 mV for Ba²⁺ was 36 ± 10 m m  ( n = 6)  , whilst for Cs⁺ it was 20 ± 6.0 m m  ( n = 5)  . H98D was more sensitive to Ba²⁺ than the wild-type (WT); in addition, the site at which Ba²⁺ appears to bind was altered (WT: δ, 0.64 ± 0.16, n = 6; H98D: δ, 0.16 ± 0.03, n = 5, statistically different from WT; H98N: δ, 0.58 ± 0.09, not statistically different from WT). Thus, the pore-neighbouring residue H98 contributes not only to the pH sensitivity of TASK1, but also to the structure of the conduction pathway.     

HLA-B8 antigen and anti-PLA1 allo-immunization

HLA-A-B-C and DR typing was performed on sixteen individuals whose PL^A1 platelet group was negative. Ten of them were immunostimulated with PL^A1 antigen by pregnancy or transfusion; six of them were responders and developed an anti-PL^A1 antibody. A high incidence of HLA-B8 antigen was observed in that group of responders. This observation is supported by five other cases of allo-immunization reported in previous papers.