Efficacy of imiquimod for the expression of Bcl-2, Ki67, p53 and basal cell carcinoma apoptosis

BACKGROUND: Imiquimod is a modifier of the immune response that has been proven to be an effective treatment for basal cell carcinoma (BCC). However, its mechanism of action is still unknown. OBJECTIVES: To determine whether imiquimod modifies the expression of proteins such as Bcl-2, Ki67, p53 and the BCC apoptotic index. PATIENTS AND METHODS: Thirty caucasian patients with primary BCCs larger than 8 mm in diameter were included in a double-blind randomized clinical and immunohistochemical study which was designed in a reference university hospital. The 30 BCCs were randomized in two treatment arms between September 2001 and February 2002. Twenty-four BCCs were treated with imiquimod 5% cream and six BCCs with Aldara (3M Pharmaceuticals) excipient. Histological samples were obtained before treatment and on days 8 and 15 during the course of treatment. The BCC expression of Bcl-2, Ki67 and p53 was determined in paraffin samples and the apoptotic index of the BCC was studied using the TUNEL technique (terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate biotin nick end labelling) in frozen samples. All variables were evaluated quantitatively in fields with a magnification x 400. RESULTS: The BCCs treated with imiquimod showed a decrease in the expression of Bcl-2 (88.7% before treatment, 61.4% day 15, P = 0.01) and an increase in the apoptotic index (0.53% before treatment, 1.66% day 15, P = 0.002), which were not observed in the BCCs treated with the excipient. Ki67 and p53 did not show significant changes in any group. CONCLUSIONS: Imiquimod reduces the expression of Bcl-2 in the BCC cells and increases the BCC apoptotic index.     

Immunohistochemical prognostic criteria in xeroderma pigmentosum

Xeroderma pigmentosum (XP) is a rare inheritable disease characterized by severe sun sensitivity and early development of skin cancers. We compared the expression of cell proliferation markers and cell cycle checkpoint regulators in squamous cell carcinomas (SCC) and basal cell carcinomas (BCC) from patients with and without XP. Immunostaining for p53, Ki-67, and proliferating cell nuclear antigen (PCNA) was determined in SCCs and BCCs from 18 XP patients and 30 controls. Nine of the 18 XP patients had SCC and BCC, and the other nine had only SCC. In the control group, 15 moderately differentiated SCCs and 15 BCCs were evaluated. Expressions of p53, Ki-67 and PCNA in XP and non-XP patients were assessed statistically by using the Chi-square method. Expression of Ki-67 and PCNA was found to be greater in SCC from XP patients than controls (P = 0.021 and P = 0.033, respectively). Expression of PCNA and p53 by BCCs was greater in XP patients (P < 0.001 and P = 0.027, respectively). There was a significant difference in Ki-67 (P < 0.001) and PCNA (P = 0.001) expression between the lesions of the XP patients who died during the follow up and XP patients who survived. In XP patients, SCCs with more than 10% Ki-67 expression and %50 PCNA expression have a poor prognosis. Our results suggest that increased Ki-67 and PCNA expression may be a predictor for recurrence of nonmelanocytic skin cancer and a poor prognosis.     

Prognostic value of Ki67 antigen expression in basal cell carcinomas

Summary Recurrence of basal cell carcinoma (BCC) following treatment is a common event and long-term follow-up of all patients presenting with a primary BCC has been recommended. Proliferation indices have been recognized as important prognostic factors in several tumour types in a variety of cancer systems, being significantly elevated in more aggressive lesions. We have examined 51 BCCs (17 non-recurrent tumours [group 1]. 17 original tumours which later recurred [group 2-0]. and the corresponding 17 recurrent specimens [group 2-R] for Ki67 antigen expression, a proliferalionassociated antigen using immunohistochemistry with the monoclonal antibody MIB1. There was a significant increase in the percentage positive for MIB1 in the Group 2-0 as compared with the group 1 BCCs (P相似文献   

The Rate and Pattern of Bcl-2 and Cytokeratin 15 Expression in Trichoepithelioma and Nodular Basal Cell Carcinoma: A Comparative Study

Context:

Histopathological evaluations can differentiate between clinically resembling trichoepithelioma (TE) and basal cell carcinoma (BCC) unless the biopsy specimens are small or superficial. Previous studies used immunohistochemical evaluation for Bcl-2 and cytokeratin 15 (CK15), in attempts to differentiate between these two entities, with heterogeneous findings.

Aims:

This study intended to compare the rate and patterns of Bcl-2 and CK15 expressions between specimens of TE and nodular BCC.

Settings and Design:

Case-series including formalin-fixed, paraffin-embedded cutaneous biopsies.

Subjects and Methods:

Twenty-two BCC and 12 TE specimens were stained for Bcl-2 and CK15 and examined microscopically. The rate and patterns of expressions were compared between the two groups.

Statistical Analysis Used:

Statistical analysis was performed using the statistical software (SPSS version 16.0; SPSS Inc., Chicago, IL, USA), Pearson Chi-square, or Fisher''s exact tests, wherever appropriate.

Results:

The two groups were comparable for the expression rate and patterns of Bcl-2 (86.4%: 5 central, 14 diffuse in BCC vs. 83.3%: 2 central, 8 diffuse in TE; P = 0.59 and 0.54 for rate and pattern, respectively). The rate of CK15 expression was significantly higher in TE specimens (66.7%: 4 central, 3 diffuse, 1 peripheral vs. 4.5%: 1 central; P < 0.001). The positive likelihood ratio in distinguishing the two neoplasms was 14.7 (95% confidence interval: 2.1-103.7).

Conclusions:

CK15 but not Bcl-2 staining may help in differentiating between BCC and TE even in BCCs with follicular differentiation.     

Expressions of p53, cyclinD1 and histopathological features in basal cell carcinomas

Background: We planned this study to analyze probable associations between p53, cyclinD1, Ki67 and histopathological features in basal cell carcinomas (BCC).
Methods: Histological differentiation types, histological growth patterns and tissue responses were analyzed in 50 cases of BCC. In immunohistochemical analysis, p53, cyclinD1 and Ki67 antibodies were investigated. P53 expression was evaluated based on a cut-off value of 25% positivity. CyclinD1 expression was graded from 0 to 3+ according to the percentage of positive nuclear staining. The percentage of positively staining cells for Ki67 was recorded.
Results: The following significant correlations were detected. Solid infiltrative type differentiation was related to the infiltrative histological growth pattern. The rates of p53 positivity and severe fibrosis in the groups of mixed and infiltrative growth patterns were higher than others. Besides, p53-positive cases showed more severe fibrosis and had a higher mean value for Ki67 index. Epidermal p53 and cyclinD1 clones in normal epidermal areas adjacent to tumors were noticed in 42% and 52% of the cases, respectively.
Conclusions: P53 expression seems to be related to Ki67 index and some histopathological features of BCC, such as infiltrative histological growth pattern and probably fibrosis.     

Assessment of Cellular Proliferation of Sebaceous Neoplasms by AgNOR Counts and Immunohistochemical Demonstrations of PCNA and Ki-67

We assessed cellular proliferation of sebaceous neoplasms by AgNOR counts and the immunohistochemical demonstration of proliferating cell nuclear antigen (PCNA) and Ki-67, using formalin-fixed and paraffin-embedded tissue specimens. We used three categories of sebaceous neoplasms: four cases of sebaceoma, three cases of basal cell carcinoma with sebaceous differentiation (BCSD), and seven cases of sebaceous carcinoma (SC). Significant differences were noted between SC and non-SC tumors (sebaceoma and BCSD) in AgNOR counts and semi-quantitative grading of PCNA and Ki-67 labelling indices (P<0.01). When a cut-off value of 6 was chosen, the AgNOR value discriminated SC from non-SC tumors with high specificity and sensitivity. When a cut-off value of 25% was chosen, PCNA and Ki-67 labelling indices also discriminated between these tumors. Significant differences were not observed between sebaceoma and BCSD with PCNA and Ki-67 labelling indices. AgNOR counts of BCSD were a little higher than those of sebaceoma, but the number of cases was too small to perform statistical assessment. We consider AgNOR counts and semi-quantitative grading of PCNA and Ki-67 labelling indices to be useful in differentiating SC from BCSD and sebaceoma.     

Bcl-2 and CD10 expression in the differential diagnosis of trichoblastoma, basal cell carcinoma, and basal cell carcinoma with follicular differentiation

Background  Both trichoblastoma and basal cell carcinoma (BCC) of the skin are characterized morphologically by the proliferation of basaloid cells; however, BCCs are clinically associated with a more aggressive behavior. An accurate diagnosis of these lesions is essential for effective, timely treatment and appropriate therapeutic decisions.
Methods  This study includes 40 lesions. Bcl-2 and CD10 immunohistochemistry were performed in all cases and the patterns of expression were analyzed.
Results  Bcl-2 is useful for the detection of BCC with diffuse expression in nests of basaloid cells, but cannot distinguish between BCC with follicular differentiation and trichoblastoma, as both lesions show the same pattern with positive and negative areas. Conversely, CD10 expression can distinguish between trichoblastomas with peritumoral stromal staining and BCCs with epithelial staining. If both stromal and epithelial areas are stained, these cases are classified as BCC with follicular differentiation.
Conclusions  CD10 is useful for distinguishing between BCC with widespread follicular differentiation and trichoblastomas.     

Basaloid/follicular hyperplasia overlying connective tissue/mesenchymal hamartomas simulating basal cell carcinomas

BACKGROUND: Basaloid hyperplasia has been described overlying dermatofibromas as well as in the epidermis overlying nevus sebaceus. Although the morphology of these areas may resemble that of basal cell carcinoma (BCC), in the majority of cases aggressive behavior of the proliferation is not seen. In fact, the basaloid proliferation often shows follicular differentiation and may be stimulated and maintained by its relationship with the underlying stromal cells. OBJECTIVE: We wanted to determine whether immunohistochemical staining for antibodies, which may suggest differences in pathogenesis, were different in basaloid hyperplasia overlying connective tissue/mesenchymal hamartomas and BCC. METHODS: We report 3 cases of connective tissue/mesenchymal hamartomas with overlying basaloid hyperplasia, in which the areas of the basaloid proliferation showed follicular differentiation. Immunohistochemical stains included Ber-EP4, PCNA, Ki-67, Bcl-2, p53, SM-Actin, CD31, factor XIIIa, KP-1, and CD34. RESULTS: There was a diffuse positive reaction for Ber-EP4 in all specimens and there was increased nuclear staining for PCNA and Ki-67. There was focal cytoplasmic staining for Bcl-2 in the areas of basaloid hyperplasia. Immunohistochemical staining for p53 showed only scattered positive cells except in a small focus in the areas of basaloid hyperplasia. The connective tissue component of all lesions showed diffuse staining for CD34 surrounding areas of basaloid hyperplasia in the mesenchymal component as well as in abundant S-100(+) nerves. CONCLUSION: The areas of basaloid hyperplasia in these hamartomas exhibited an immature phenotype similar to that seen in both BCCs and follicular tumors; however, the patterns of proliferation markers, p53, Bcl-2, and the surrounding stromal cell markers were similar to those of benign follicular tumors. Thus the staining pattern for this group of antibodies suggests that areas of basaloid hyperplasia are not BCC.     

Lamin expression in normal human skin,actinic keratosis,squamous cell carcinoma and basal cell carcinoma

BACKGROUND: Aberrant expression patterns of nuclear lamins have been described in various types of cancer depending on the subtype of cancer, its aggressiveness, proliferative capacity and degree of differentiation. In general, the expression of A-type lamins (lamins A and C) has been correlated with a non-proliferating, differentiated state of cells and tissues. OBJECTIVES: To establish and compare the expression patterns of lamins in normal human skin, actinic keratosis (AK), squamous cell carcinoma (SCC) and basal cell carcinoma (BCC). METHODS: Expression patterns of the individual lamin subtypes were studied immunohistochemically. The proliferation capacity of the tumour cells was detected using a specific antibody to Ki-67, and was related to the A-type lamin expression patterns. RESULTS: In normal skin, lamin A was expressed in the suprabasal cell compartment of the epidermis, whereas the basal cells were mostly unstained. BCCs and SCCs stained positive in most cells, while the epidermis overlying BCC and SCC and the epidermis in AK stained homogeneously and strongly in the basal cells in addition to the suprabasal cells. Lamin C was expressed in some basal cells of normal epidermis while the suprabasal cells stained strongly positive. Both BCCs and SCCs stained strongly positive for lamin C, with the difference that in BCC the staining was predominantly present in nucleolar structures with occasional staining of the nuclear envelope. The epidermis overlying SCC showed strong positivity in the lamina of virtually all cells. The expression of lamin C in the basal cells of AK resembled the expression pattern seen in the epidermis overlying BCC, i.e. a nucleolar staining next to nuclear envelope staining. Lamin B1 and B2 were found in virtually all cells in normal epidermis, AK, BCC, SCC and the epidermis overlying cancer. The percentage of Ki-67-expressing cells was highest in BCC (45%), and gradually decreased via epidermis overlying BCC, AK, SCC, and epidermis overlying SCC, to normal skin (11%). Simultaneous expression of A-type lamins and Ki-67 occurred in approximately 50% of the proliferating (Ki-67 positive) cells in BCC and SCC. CONCLUSIONS: Significant changes occur in the expression patterns of A-type lamins in both premalignant and malignant lesions of the skin. The profound overlap of lamin A and Ki-67 staining patterns indicates that the proliferating tumour cells may obtain a certain degree of differentiation. Finally, lamin A expression in the basal cell layer of the apparently normal epidermis overlying BCC may suggest its involvement in the primary process.     

Open study of the efficacy and mechanism of action of topical imiquimod in basal cell carcinoma

Imiquimod is an immune-response modifier that has been shown to be effective in the treatment of superficial and nodular basal cell carcinoma (BCC). The objective of this open-label study was to investigate the effectiveness of imiquimod 5% cream in superficial, nodular, and infiltrative BCC. Fifty-five Caucasian patients with primary BCC measuring 8 mm or more in diameter with a superficial, nodular, or infiltrative histological pattern were included in the study. Four groups of BCC (A, B, C, and D) and two dosing regimens were studied: 35 BCCs (groups A, B, and C) were treated with imiquimod three times weekly and 20 BCCs (group D) were treated with imiquimod five times weekly. Histological samples were obtained before treatment, during treatment (on day 22 in group A, day 15 in group B, and day 8 in groups C and D), and 6 weeks after treatment. All patients were followed-up for a minimum of 2 years. In the biopsy specimens obtained, the expression of Bcl-2, p53, and Ki-67, apoptotic index (Tunel technique), and the number of CD3+, CD8+, CD20+, CD56+, CD68+, granzyme B+, and S-100+ cells in the peritumoural inflammatory infiltrate, were determined and quantified. Of the 55 BCCs treated with imiquimod 41 (74%) were in complete remission after 2 years of follow-up. These comprised 4/4 superficial BCCs, 7/8 (88%) nodular BCCs, and 30/43 (70%) infiltrative BCCs. Multi-variate analysis demonstrated that baseline tumour size was the most powerful independent prognostic variable (P < 0.05). Treatment with imiquimod increased the apoptotic index (P < 0.05), reduced Bcl-2 expression (P < 0.05), and increased the number of CD3+, CD8+, CD20+, CD68+, granzyme B+, and S-100+ cells in the inflammatory infiltrate of the BCC (P < 0.05). In conclusion, imiquimod induced an antitumour immune response mediated by lymphocytes and macrophages, reduced Bcl-2 expression and increased the apoptotic index of BCC, and was clinically effective in 74% of BCCs after a 2-year follow-up period.     

Expression of bcl-2, p53 and Ki-67 in arsenical skin cancers

To investigate the regulation of apoptosis and proliferation in arsenic-induced skin cancers, we examined the expression of bcl-2. p53, and Ki-67 using immunohistochemical staining. Thirty patients with Bowen's disease (BD), ten with basal cell carcinoma (BCC), eight with squamous cell carcinoma (SCC) and eleven of perilesional normal skin (PLN) of the non-sun exposure sites from endemic area were examined. The results showed that: 1) bcl-2 was expressed in all of the BCC homogeneously, in none of the SCC, and in 12/30 of the BD focally or homogeneously; 2) p53 was expressed in all of the arsenical skin cancers with a labelling index of 75±14% of BD, 50±17% of BCC. 61±15% of SCC, and also in all of the perilesional normal skin with a labelling index of 55±24%; 3) Ki-67 was expressed in all of the skin cancers with labelling index of 58±17% of BD. 12±7% of BCC, 47±21% of SCC, and in 9/11 of PLN with a labelling index of 41±24%. Expression of bcl-2 in BCC or BD is related to the phenotype of germinative basal cell. The constant expression of bcl-2 i early dysplastic cells of BD and the earliest expression of P53 in the basal cells of perilesional normal skin indicate that the initial step of arsenic-induced carcinogenesis is from the basal germinative cells. There is no mutual relationship between bcl-2, p53 or Ki-67 expression in any type of the arsenical skin cancers, but there is a positive correlation between p53 and Ki-67 expression identified in perilesional normal skin. BD had the highest labelling index of p53 and Ki-67.     

Bax expression and growth behavior of basal cell carcinomas

BACKGROUND: To understand the typical growth behavior of basal cell carcinoma (BCC) we searched for the correlation between proliferation and apoptosis and progression of BCC. METHODS: Expression of Bcl-2, Bax, and Ki-67 was immunohistochemically investigated in both normal skin and BCC cells, as well as in the epidermis overlying BCC. RESULTS: The results showed that in normal epidermis, Bcl-2 was homogeneously expressed in the basal cell compartment, whereas Ki-67 expression was largely restricted to the parabasal layer, the layer just above the basal cell layer, and exhibited a more scattered staining pattern. Bax was occasionally expressed in the basal layer and widely in the suprabasal compartment. Strikingly, the apparently normal epidermis overlying BCC showed an increased Bd-2 staining. In BCC, cells stained homogeneously for Bcl-2, whereas Bax and Ki-67 showed scattered staining patterns. Simultaneous expression was seen for Bcl-2 and Bax in 80 +/- 7% of the tumor cells, and co-expression of Bcl-2 and Ki-67 in 20 +/- 7% of the tumor cells. The cells expressing Bcl-2 and Ki-67, but lacking expression of Bax, the progressive fraction, comprised on average 7 +/- 3% of the tumor cell population. CONCLUSION: These results suggest that this small progressive fraction of tumor cells, in combination with the relatively high percentage of cells still prone to apoptosis, can explain the indolent growth behavior of BCC.     

Expression of p53 in arsenic-related and sporadic basal cell carcinoma

BACKGROUND: The TP53 gene has been shown to have an important role in the genesis of sporadic, presumably mainly sunlight-related, basal cell carcinoma (BCC). However, its role in arsenic-related BCCs is not clear, although the trivalent form of arsenic has been long recognized as a cause of BCC. Arsenic treatment has been shown to cause hypermethylation of the TP53 gene in lung carcinoma cell lines, but it is not known if this occurs in vivo in arsenic-related BCCs. OBJECTIVE: To compare the immunohistochemical expression of the p53 protein in arsenic-related and sporadic BCCs to determine if the expression pattern is consistent with gene silencing. SETTING: A research institute and hospital in Australia. CASES: One hundred seventeen white patients with 121 sporadic BCCs and 21 white patients with 92 arsenic-related BCCs. MAIN OUTCOME MEASURES: The expression and the intensity of p53 were scored semiquantitatively. Statistical analysis was performed using the chi2 test. RESULTS: Arsenic-related BCCs express p53 less often and at a lower intensity than sporadic BCCs (P = .001; 2-tailed test). The BCCs from sun-exposed sites, whether arsenic related or sporadic, more frequently showed overexpression of p53 than those from less-exposed areas (P = .004; 2-tailed test). The more aggressive subtypes of BCC show a higher level of expression of p53 than the less aggressive forms (P = .04; 2-tailed chi2 test). CONCLUSIONS: These results are consistent with the hypothesis that the TP53 gene is down-regulated by methylation in arsenic-related BCC, particularly those from less-exposed sites. However, an alternative possibility is that mutations in TP53 that stabilize the protein are less common in arsenic-related BCCs. Further analysis will be necessary to distinguish between these hypotheses.     

Basal cell carcinoma in association with multiple trichoepitheliomas

We report the case of a basal cell carcinoma (BCC) associated with multiple trichoepitheliomas (TEs) and include the results of histopathological and immunohistochemical studies. The patient had a large, pigmented nodule associated with 4 flesh-colored papules in the central facial area. Two of the 4 flesh-colored papules and the large pigmented nodule were excised. Histopathologically, the pigmented nodule was diagnosed as BCC and 2 of the papular lesions were diagnosed as TEs. In both the BCC and TEs, almost all of the basaloid aggregations were diffusely positive for cytokeratin (CK) 19, CK8 and CK8/18. Based on these clinicopathological observations and reports in the recent literature, these two neoplasms are considered to be highly related. BCC appears to differentiate toward follicular germinative cells, and TE is its benign counterpart.     

Basal cell carcinomas arising within multiple trichoepitheliomas

Although trichoepitheliomas (TEs) are commonly regarded as benign tumors of follicular origin, the natural history of multiple familial trichoepitheliomas (MFT) and their risk for malignancy has been unclear. We describe a 57-year-old male with numerous skin-colored firm papules and plaques present on the central face since 6 years of age. Recently, some lesions had enlarged and ulcerated. Other family members were similarly affected. Biopsies from multiple lesions showed TEs both alone and associated with basal cell carcinoma (BCC) in the same section, suggesting the secondary development of BCCs within TEs. Many prior reports of BCCs arising within TEs in patients with presumed MFT were likely misdiagnosed cases of nevoid BCC. This report is a compelling example of MFT in which BCCs evolved secondarily. Awareness of the potential for the evolution of carcinoma in patients with MFT is important in the management of these patients.     

Ki-67 antigen expression and growth pattern of basal cell carcinomas

The expression and location of the Ki-67 antigen was investigated in 62 basal cell carcinomas (BCC) using immunostaining techniques (PAP and APAAP) on cryostat sections. The tumor samples were classified into three groups according to microarchitecture (nodular, superficial or fibrosing). The Ki-67 growth fraction displayed great variation between tumors belonging to the same group (nodular type, 7–67%; superficial type, 18–49%; fibrosing type 4–33%). In nodular and superficial BCC formations Ki-67 reactivity was confined either to the nuclei of three to five rows of peripheral cells, or Ki-67-positive nuclei were scattered in the central as well as in the peripheral parts of the tumor strands. The staining patterns varied in an individual tumor. Areas with a high Ki-67 labelling index often occurred adjacent to rather quiescent strands, suggesting that an individual tumor is not in a uniform state of proliferation. So far there are no experimental findings on the regulation of proliferative activity in BCCs. In view of the fact that BCCs are rather slow-growing tumors, the large Ki-67 growth fractions indicate a prolonged duration of the cell cycle or a considerable continuous loss of cells. As the microarchitecture of BCCs is much more complex than would be expected from the location of their Ki-67-positive cells, the growth pattern is probably determined to a high degree by the adjacent connective connective tissue (physical properties and texture of collagen and elastic fibres, enzyme activity of fibroblasts).     

Immunohistochemical study on keratin expression in certain cutaneous epithelial neoplasms. Basal cell carcinoma, pilomatricoma, and seborrheic keratosis

We investigated immunohistochemically 20 basal cell carcinomas (BCC), five pilomatricomas, and nine seborrheic keratoses using anti-BCC keratin monoclonal antibody (BKN-1) and anti-hair keratin monoclonal antibodies (HKN-2, HKN-4- -7). The neoplastic cells in all the cases of BCC were always uniformly stained by BKN-1, HKN-2, and HKN-4, indicating that the BCC cells display a constant antigenicity of keratin, which may be different from that of the normal epidermis. Although no fluorescence by HKN-6 or HKN-7 was seen in any cases of BCC, HKN-5 partially but strongly stained the neoplastic nests in most cases of BCC; BCC may have differentiation toward the lower part of hair follicular epithelium. In pilomatricoma, all the anti-keratin monoclonal antibodies showed a similar staining pattern; the differentiating neoplastic cells undergoing transition from basaloid to eosinophilic were positively stained by each antibody in all the cases. This finding of pilomatricoma corresponds to that of the differentiating cells in the inner hair layers, especially in the hair cortex. In seborrheic keratoses, no fluorescence was recognized with HKN-5- -7, which stain the lower follicular cells in the normal human skin. The staining patterns of seborrheic keratosis by BKN-1, HKN-2, and HKN-4 were similar to those of the normal interfollicular epidermis. These anti-keratin monoclonal antibodies seem to be useful for the investigation of the direction of differentiation of skin adnexal neoplasms.     

Somatic mutations in the PTCH, SMOH, SUFUH and TP53 genes in sporadic basal cell carcinomas

BACKGROUND: Basal cell carcinoma (BCC) of the skin is the most common human cancer. The genetic alterations underlying BCC development are only partly understood. OBJECTIVES: To investigate further the molecular genetics of sporadic BCCs, we performed mutation analyses of 10 skin cancer-associated genes in 42 tumours. METHODS: Single-strand conformational polymorphism analysis followed by DNA sequencing was used to screen for mutations in the sonic hedgehog pathway genes PTCH, SMOH, SUFUH and GLI1, in the TP53 tumour suppressor gene, and in the proto-oncogenes NRAS, KRAS, HRAS, BRAF and CTNNB1. Microsatellite markers flanking the PTCH, SUFUH and TP53 loci at 9q22, 10q24 and 17p13, respectively, were studied for loss of heterozygosity (LOH). RESULTS: PTCH mutations were found in 28 of 42 tumours (67%). Microsatellite analysis revealed LOH on 9q22 in 20 of 38 tumours investigated (53%), including 14 tumours with and six tumours without PTCH mutations. SMOH mutations were identified in four of the 42 BCCs (10%) while two tumours demonstrated mutations in SUFUH, including one missense mutation and one silent mutation. None of the BCCs showed LOH at markers flanking the SUFUH locus. Seventeen BCCs (40%) carried TP53 mutations, with only three tumours showing evidence of biallelic TP53 inactivation. TP53 mutations were present in BCCs with and without mutations in PTCH, SMOH or SUFUH. Interestingly, 72% of the TP53 alterations were presumably ultraviolet (UV)-induced transition mutations. In contrast, only 40% of the PTCH and SMOH alterations corresponded to UV signature mutations. No mutations were identified in GLI1, NRAS, KRAS, HRAS, BRAF or CTNNB1. CONCLUSIONS: Our data confirm the importance of PTCH, SMOH and TP53 mutations in the pathogenesis of sporadic BCCs. SUFUH alterations are restricted to individual cases while the other investigated genes do not appear to be important targets for mutations in BCCs.     

Expression of beta-catenin in basal cell carcinoma

Background beta-Catenin is a crucial member of the E-cadherin/catenin complex, which plays a major role in cell-cell adhesion. beta-Catenin is also known to be involved in signal transduction pathways. Many studies have demonstrated changes in the expression of beta-catenin in colorectal carcinomas, suggesting a role for beta-catenin in neoplastic development. Objectives Basal cell carcinoma (BCC) is a locally invasive tumour. The various subtypes show differences in biological behaviour. This study aimed to investigate the presence of differences in the immunoprofile of beta-catenin among histological variants of BCC. Methods Eighty BCCs were studied (32 nodular, 7 micronodular, 24 superficial and 17 infiltrative and morphoeic). Formalin-fixed, paraffin-embedded tissue sections were stained for beta-catenin using the avidin/biotin immunodetection technique. Results All the nodular BCCs showed membranous and weak cytoplasmic staining. Nuclear staining was seen in 15 of 32 (47%) cases, being stronger at the periphery of the nodules in 11 of 15 (73%) of these cases. In superficial BCCs the membranous staining was variable and cytoplasmic staining was increased. Nuclear staining was seen in 16 of 24 (67%) cases, being more notable at the periphery in 8 of 16 (50%) of these cases. All micronodular BCCs showed strong membranous staining, weak cytoplasmic and no nuclear staining. In the infiltrative and morphoeic BCCs membranous staining was completely lost at the advancing margins of the invading cell strands, with a marked increase in cytoplasmic staining; nuclear staining was observed in all these tumours. Conclusions The expression of beta-catenin varied between different types of BCC. Nuclear localization was most notable in the infiltrative and morphoeic variants, followed by the superficial variant, and seen least in nodular BCC. Its prominence at tumour margins suggests that this may be associated with more aggressive types of invasion.