Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P10415 (Bcl-2)
 33,771 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Previous models of cutaneous carcinogenesis have primarily focused on the regulation of keratinocyte (KC) proliferation and differentiation. However, it has become clear in many neoplastic systems that altered rates of cell death and/or inability to undergo growth arrest can also contribute to the development of cancer. Apoptosis-regulatory proteins include those that block apoptosis such as Bcl-2 and Bcl-x, whilst a related protein Bax promotes apoptosis. Cell cycle regulatory proteins include those associated with growth arrest, i.e. p21wafl, p53, and those associated with proliferation, i.e. Ki-67. Paraffin embedded samples from ten different lesions of squamous cell carcinoma (SCC), Bowen's disease (BD), keratoacanthomas (KA), and nine normal adult skin samples were stained by immunohistochemistry to detect expression of Bcl-2, Bcl-x, Bax, Ki-67, p21wafl, p53 and apoptosis (TUNEL assay). Compared to low levels of Bcl-x and Bcl-2 immunostaining in normal skin, all the squamoproliferative lesions had strong and diffuse KC expression of Bcl-x (>80%) but minimal to absent KC Bcl-2 expression (<15%). Bax immunopositivity was limited to the basal layer in normal skin and BD. In contrast, by examining serial sections both Bcl-x and Bax appeared to be coexpressed by the majority of malignant KCs in KA and SCC (>70%). These immunostaining profiles reveal that squamoproliferative lesions, including invasive transformed KCs, preferentially express Bcl-x over Bcl-2, in addition to upregulating their Bax levels. Even though there were numerous TUNEL positive cells in these squamoproliferative lesions, no other evidence of apoptosis was seen reinforcing the necessity to use caution when relying on TUNEL staining for identification of programmed cell death in skin biopsies. Normal sun-exposed skin had low but detectable p53 and rare p21wafl KC expression. Significantly higher numbers of p21wafl and p53 immunopositive KCs were noted throughout the lesions in BD and SCC in contrast to KA where p53 and rare p21wafl immunopositive KCs were primarily limited to the periphery of the tumor cell islands. In general, p53 KC expression was higher in all squamoproliferative lesions and sun-exposed normal skin compared to p21Wafl expression. Summary of the expression of cell cycle regulatory proteins for both p21wafl and p53 KC expression was: SCC > BD > KA, in marked contrast to Ki-67 KC expression which was: BD > KA > SCC. The relatively few malignant cells in SCC that were actively participating in the cell cycle (i.e. Ki-67 positive) suggests that these neoplasms may arise primarily by increased cell survival and resistance to apoptosis rather than by hyperproliferation. These studies emphasize the importance of examining multiple members of protein families that regulate apoptosis, proliferation, growth arrest, and differentiation. It is the overall balance between these cellular phenomena that determine whether a cell remains viable or undergoes programmed cell death and contributes to the appearance of a neoplasm. The overexpression of Bcl-x may confer a survival advantage to malignant KCs unable to growth arrest to repair damaged DNA (mutant p53) and/or undergo terminal differentiation (increased p21wafl). Thus, mutation or aberrant expression of such proteins may participate in the multistep process of carcinogenesis that gives rise to these squamoproliferative lesions.
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PMID:Differential expression of cell survival and cell cycle regulatory proteins in cutaneous squamoproliferative lesions. 989 Mar 76

We examined the presence of human papillomavirus (HPV) DNA in tissues of premalignant skin lesions, i.e., actinic keratosis (n = 13) and Bowen's disease (n = 62), taken from 69 Japanese immunocompetent and renal transplant recipient patients. Detection and typing of HPV DNA were performed using polymerase chain reaction (PCR) and sequence analysis or restriction fragment length polymorphism (RFLP) analysis, respectively. The positivity rates of HPV DNA in tissues of actinic keratosis and Bowen's disease were 77% and 65%, respectively. Twenty-seven HPV types were detected in 50 (67%) premalignant skin lesions, in which Z95963 (accession no. in the EMBL Databank), Z95968, AJ010823, and AJ000151 have been described as partial sequences of unknown HPV types. Furthermore, 2 unknown types, HPVX1 and HPVX2, were found in specimens of actinic keratosis. Sequence analysis showed that HPVX1 is related to HPV-37 (86.1% sequence homology) and that HPVX2 is related to HPV-38 (79.7%). These results indicate that various mucosal and epidermodysplasia verruciformis-related HPV types are associated with the pathogenesis of actinic keratosis and Bowen's disease. In addition, 24 specimens of HPV-positive or HPV-negative premalignant skin lesions were examined immunohistochemically for proliferating cells to determine biological differences between HPV-positive and HPV-negative lesions. Immunohistochemistry for p21(Waf1/Cip1), p53, proliferating cell nuclear antigen (PCNA), Ki-67, and Bcl-2 revealed that there was no significant difference in the cell proliferation activity between HPV-positive and HPV-negative lesions, suggesting that HPV infection alone does not induce cell proliferation in those lesions.
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PMID:Human papillomavirus infection in actinic keratosis and bowen's disease: comparative study with expression of cell-cycle regulatory proteins p21(Waf1/Cip1), p53, PCNA, Ki-67, and Bcl-2 in positive and negative lesions. 1456 84

Although arsenic and ultraviolet light B (UVB) are both causes for skin cancers, lesions of arsenic-induced Bowen's disease are often confined to sun-protected skin. UVB may play a modulatory role in skin carcinogenesis by arsenic. The purpose of this study was to evaluate the effects and interactions of arsenic and UVB on cell cycle progression and apoptosis. Cultured human keratinocytes were treated with sodium arsenite (1 microM) and/or UVB (50 mJ/cm(2)) irradiation in different combinations: (i) arsenic alone, (ii) UVB alone, (iii) arsenic followed by UVB (As-UVB), and (iv) UVB followed by arsenic (UVB-As) treatments. Cell cycle analysis and BrdU pulsing revealed S phase arrest in all treatment groups and growth arrest in As-UVB and UVB-As groups. The terminal deoxynucleotidyl transferase-mediated deoxyuridine nick-end labeling assay showed a higher apoptosis rate in the UVB-As group as compared to that of the As-UVB and UVB groups. UVB irradiation significantly decreased Bcl-2 expression. In either the As-UVB or the UVB-As group, the expression of Bcl-2 was further suppressed as compared to the UVB group. The caspase-3, -8, and -9 relative activities were all increased in the UVB group; however, arsenic significantly enhanced caspase-8 and -3 relative activities in UVB-irradiated keratinocytes (the UVB-As group). Pretreatment with the caspase inhibitor(s) rescued the keratinocytes viability to different degrees with the least in the UVB-As group. Our findings revealed that arsenic enhances UVB-induced keratinocyte apoptosis via suppression of Bcl-2 expression and stimulation of caspase-8 activity. Combined UVB and arsenic treatment resulted in the antiproliferative and proapoptotic effects in keratinocytes. Our results provide the explanation for the rare occurrences of arsenical cancers in the sun-exposed skin and the potential therapeutic role of UVB in arsenic-induced Bowen's disease.
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PMID:Effects and interactions of low doses of arsenic and UVB on keratinocyte apoptosis. 1537 53

The aim of our study was to elucidate the characteristics of HPV expression and cell proliferation in actinic keratosis and Bowen's disease of the skin. We examined immunocompetent patients with premalignant lesions of the skin such as actinic keratosis and Bowen's disease. 10 patients were involved in each group. Clinical study included gross features of lesion, growth rate, colour, size. Paraffin sections from biopsy specimens were were stained by hematoxylin-eosin and von Gieson. Immunohistochemistry was performed using monoclonal antibodies against HPV, oncoprotein p53, anti-apoptotic protein Bcl-2, proliferation marker PCNA. Strongly, moderately and weakly positive cells were counted. Actinic keratosis and Bowen's disease failed to show the specific clinical features, therefore, they can not be diagnosed based on clinical signs only and morphological examination seems to be mandatory. The immunohistochemical study has showed that in both actinic keratosis and Bowen's disease HPV was positive in 60%, and 40% were HPV-negative suggesting the similar incidence of HPV infection in these premalignant lesions. Our results suggest that HPV(+)/p53(+) types of actinic keratosis and Bowen's disease are characterized by higher proliferation activity in comparison to HPV(-)/p53(+) types, and expression of Bcl-2 is associated with HPV-negativity, therefore, these premalignant lesions of the skin require immunohistochemical examination with evaluation of expressions of human papillomavirus, proliferation marker PCNA and anti-apoptotic protein Bcl-2. The differential diagnosis of actinic keratosis and Bowen's disease should be based on the following immunohistochemical criteria: incidences of positivity for p53, Bcl-2 and PCNA are similar, but expression intensity and anatomical localization are different: their expressions are higher in Bowen's disease, positive cells are found primarily in upper epidermis in actinic keratosis, while whole epithelium is involved in Bowen's disease.
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PMID:The characteristics of human papillomavirus expression and cell proliferation in actinic keratosis and Bowen's disease of the skin. 1690 62