Mutations of the TERT promoter are common in basal cell carcinoma and squamous cell carcinoma.

Telomerase is frequently expressed in cancer and contributes to carcinogenesis. Two recent publications report the identification of a set of recurrent mutations in melanoma in the promoter of the telomerase reverse transcriptase gene (TERT) that appears to be the result of mutagenesis from ultraviolet (UV) radiation. Both groups reported that the mutations increase the transcription of TERT. This prompted our search for similar mutations in two other UV-related skin cancers, basal cell carcinoma, and squamous cell carcinoma. We found that the activating TERT promoter mutations reported in melanoma are also frequent in squamous cell carcinoma (50%) and basal cell carcinoma, the latter including both sporadic tumors (78%) and tumors from patients with nevoid basal cell carcinoma syndrome (68%). These mutations were found in only 1 of 11 Bowen's disease (squamous cell carcinoma in situ) specimens, and in none of 15 non-malignant skin specimens and 57 blood specimens. The mutations were frequently homozygous or hemizygous, with little or no normal signal at the mutated positions. These data suggest that TERT promoter mutations are the most frequent putative oncogenic mutations in cutaneous cancer.

Cathepsin K expression in basal cell carcinoma.

BACKGROUND: Cathepsin K is a cysteine protease with strong collagenolytic and elastolytic properties. Recently, cathepsin K expression in tumour cells of malignant melanoma and in the stromal cells of squamous cell carcinoma of the skin has been reported to play an important role in tumour progression. However, its expression profile in basal cell carcinoma (BCC) has not yet been clarified. OBJECTIVE: The aim of this study is to examine the expression profile of cathepsin K in both the tumour cells and the peritumoural stromal cells of BCC in comparison with its expression in normal skin. METHODS: Fifty consecutive operative cases of BCC, 10 cases of actinic keratosis, 10 cases of Bowen's disease and five normal skin tissues were assessed for cathepsin K expression by immunohistochemical methods. RESULTS: In normal skin, cathepsin K expression was observed in the stratum corneum, mature sebaceous cells and outer root sheath of the hair follicles. Cathepsin K was expressed in the tumour cells of all BCC cases, in which 90% showed diffuse expression (>51% of tumour cells), as well as in the peritumoural stromal cells in all BCC cases. Focal cathepsin K expression was observed in the tumour cells of Bowen's disease (2/10 cases), but not in any of actinic keratosis (0/10 cases). CONCLUSION: Cathepsin K expression may contribute to tumour invasion and peculiar histopathological features, such as fibromucinous stroma around the tumour nests by mediating extracellular matrix degradation in BCC.

A combined assay of hTERT and E6 oncoprotein to identify virus-infected keratinocytes with higher telomerase activity in human papillomaviruses 16 and 18-related bowenoid papulosis.

In the present study, we aim to evaluate the application potential of a combined assay of human telomerase reverse transcriptase (hTERT) and E6 oncoprotein in screening the virus-infected keratinocytes with higher telomerase activity in human papillomaviruses (HPV) 16- and 18-related bowenoid papulosis (BP). HPV16/18 DNA in BP (n = 123) was identified by in situ hybridization, the expression of hTERT and E6 in HPV16/18-related BP (n = 68) was determined by immunohistochemistry. We demonstrated that the expression of hTERT correlated well with that of E6 oncoprotein in HPV16/18-related BP lesions (Spearman rho = 0.868, P < 0.01). Furthermore, the majority of keratinocytes with positive nuclear staining for hTERT or E6 in the consecutive sections of each HPV16/18-related BP lesion showed nuclear paleomorphism or nuclear mitosis. In conclusion, we suggested that a combined assay of hTERT and E6 oncoprotein can be used to screen the HPV-infected keratinocytes with higher telomerase activity in HPV16-related and HPV18-related BP lesions.

Differential expression patterns of MMPs and their role in the invasion of epithelial premalignant tumors and invasive cutaneous squamous cell carcinoma.

Co-expression of several members of the matrix metalloproteinase (MMP) family is characteristic of human malignant tumors. MMP-2, MMP-9, TIMP-2, and MT1-MMP are thought to be involved in the process of destruction of basement membranes and stromal invasion by neoplastic epithelial cells. In this study, we investigated the expression and role of MMPs in cutaneous oncogenesis. Tissue microarray consisting of 62 squamous cell carcinomas (SCC), 32 Bowen's disease (BD) samples, 25 normal epidermis samples were obtained for the study. MMP-2,-9, MT1-MMP and TIMP-2 proteins were examined by immunohistochemical staining and mRNA level was detected by quantitative RT-PCR in fresh tissues consisting of 5 cutaneous SCCs and paired normal epidermis samples. Gelatinase activity of MMP-2 and MMP-9 was investigated by gelatin zymography and protein levels of MT1-MMP and TIMP-2 were measured by western blot in 2 human SCC cell lines. The invasive property was evaluated with invasion assays using Transwell filters. SCC exhibited significantly increased MMP-2, MT1-MMP and decreased TIMP-2 mRNA and protein expression compared to that of the normal epithelium. Immunohistochemical staining revealed that MT1-MMP was strongly expressed on the invasive front of SCCs, whereas BD exhibited higher expression around the dyskeratotic cells in the epithelium. In comparison with the expression observed in BD, SCC exhibited significantly increased MMP-2 expression. In addition, high MMP-2 and MT1-MMP expression and low TIMP-2 expression had a significant positive correlation with the invasiveness of SCC cell lines in vitro. Our results revealed significantly increased MT1-MMP and MMP-2 expression and decreased TIMP-2 expression in cutaneous SCC, and the expression correlated with the invasiveness of SCC cell lines. Therefore, the expression of these factors in cutaneous tumors may serve as an indicator of tumor aggressiveness and invasion.

Evaluation of telomerase activity in non-genital Bowen's disease.

We investigated the level of telomerase activity (TA) in 17 specimens of non-genital Bowen's disease (BD) and in 14 specimens of skin without sun exposure (non-exposed skin) using a non-isotopic PCR-based telomeric repeat amplification protocol (TRAP) assay. Expression of human telomerase reverse transcriptase (hTERT; the catalytic subunit of telomerase) was also evaluated by immunochemistry in the non-genital BD tissues. Moderate to high levels of TA were detected in 41.2% of 17 non-genital BD specimens (P = 0.001). In contrast, TA was not evident in non-exposed skin. Recently, nucleolin was reported to be associated with hTERT, so we used this antibody instead of hTERT antibody. Immunohistochemistry showed that nucleolin expression was associated with high TA levels in non-genital BD. Our results also revealed differences of TA levels among non-genital BD specimens. High levels of TA in those specimens were not age related. Five out of 7 specimens (71.4%) with moderate to high TA levels were from sun-exposed sites, while the remaining 10 specimens with low levels of TA were from non-exposed sites. These results suggested that cellular DNA damage caused by ultraviolet irradiation might be associated with an increase of TA in non-genital BD. Among non-genital BD specimens, 4 out of 17 (23.5%) showed high levels of TA (median relative TA value: 79.8%; P = 0.003), which might be associated with immortalization or transformation to invasive squamous cell carcinoma.

Bowen's disease with high telomerase activity.

We describe an 81-year-old Japanese woman who had a palm-sized, erythematous plaque with a nodular lesion on the lateral abdomen. The biopsy specimens taken from the erythematous plaque and reddish nodule show that bowenoid changes were present in the epidermis and epidermis to dermis, respectively. A sentinel lymph node biopsy (SNB) was performed with blue dye and radioisotope in her right groin region and two lymph nodes were found to be occupied by many atypical cells. The erythematous plaque with nodular lesion was completely removed with a 3-cm margin under general anesthesia, and complete regional lymph node dissection was also performed. In addition, high telomerase activity was seen in the erythema plaque while using a telomeric repeat amplification protocol assay. In conclusion, some instances of Bowen's disease might have high telomerase activity in the atypical cells and can progress to Bowen's carcinoma. The SNB was regarded as a useful method to detect early lymph node metastases in this case.

The higher incidence of squamous cell carcinoma in renal transplant recipients is associated with increased telomere lengths.

The incidence and aggressiveness of nonmelanoma skin cancers, including basal cell carcinoma and squamous cell carcinoma (SCC), in immunocompromised renal transplant recipients (RTRs) is dramatically higher (up to 100-fold) compared with the normal population. SCC lesions are also predominant in RTRs, in contrast to the normal population where basal cell carcinoma is more common. The mechanisms underlying this phenomenon are unknown, but effective treatments for these skin tumors would have a significant impact upon morbidity in this group of patients. The fundamental role of telomeres and telomerase in the development of most human cancers, including melanoma, is well established, but very few reports have assessed their function during the onset of nonmelanoma skin cancer. To assess whether telomere maintenance plays any role in the increased incidence of SCC in renal transplant patients, we analyzed both the telomere lengths and telomerase expression levels in 44 SCCs and 22 Bowen's disease (BD) samples (carcinoma in situ) from RTRs and nontransplant patients. Our findings provide statistically significant evidence that the telomeres are consistently longer in both BD RTR and SCC RTR lesions compared with their nontransplant counterparts. We also show by immunohistochemistry that there is a trend toward higher telomerase levels in both the BD RTR and SCC RTR lesions, although this was not statistically significant. Our data thus suggest that telomere lengthening may possibly be an early event in the development of SCC in renal transplant patients and demonstrate that telomere maintenance mechanisms should be further evaluated with respect to developing a future therapeutic strategy for these cancers.

Cyclooxygenase-2 expression and angiogenesis in squamous cell carcinoma of the skin and its precursors: a paired immunohistochemical study of 35 cases.

BACKGROUND: Cyclooxygenase (COX)-2 expression and tumour-induced angiogenesis appear to be increased in squamous cell carcinoma (SCC) of the skin. In other cancers, COX-2 is a pro-angiogenic factor. The association between angiogenesis and COX-2 has not been studied in skin cancer. OBJECTIVES: To assess the onset of increased COX-2 expression and angiogenesis in the multistage carcinogenesis of SCC as well as the correlation between those two parameters. PATIENTS/METHODS: We performed a retrospective paired immunohistochemical analysis of normal skin, actinic keratosis (AK), Bowen's disease (BD) and SCC among 35 individuals. Specimens were considered COX-2 immunopositive when 5% or more of the tumour cells showed clear evidence of immunostaining. To quantify active angiogenesis, we used a Ki-67-CD34 double-labelling immunohistochemical stain and calculated the fraction of proliferating endothelial cells. The Chalkley method was used to determine the microvessel density. To detect hypoxia, a carboanhydrase IX immunostain was used. RESULTS: Compared with normal epidermis (0%), AK (31%), BD (22%) and SCC (40%) were significantly more likely to be COX-2 immunopositive (P < 0.01). The fraction of proliferating endothelial cells and the Chalkley scores paralleled multistage carcinogenesis (P < 0.05 between different stages). COX-2 immunopositivity was fairly correlated with hypoxia and higher proliferating endothelial cell fractions but not with Chalkley counts. CONCLUSIONS: Induction of COX-2 expression and angiogenesis are both early events in the development of SCC. In addition to ultraviolet light, hypoxia and COX-2 may be involved in skin tumour angiogenesis.

Cyclooxygenase-2 is a possible target of treatment approach in conjunction with photodynamic therapy for various disorders in skin and oral cavity.

BACKGROUND: Anti-cancer effects of cyclooxygenase (COX)-2 inhibitors have been reported, but not fully investigated in skin and oral diseases. 5-aminolaevulinic acid (ALA)-based photodynamic therapy (PDT) for treating those patients with skin and oral lesions is a highly sophisticated procedure, but the incidence of disease recurrence after treatment is rather significant. OBJECTIVE: To confirm that COX-2 could be a molecular target in adjunctive therapy to ALA-based PDT, we investigated (i) COX-2 expression in various skin and oral diseases, and (ii) the inhibitory effects on cellular growth of COX-2 selective inhibitor (nimesulide), ALA-based PDT and their combination on human oral squamous cell carcinoma (SCC) cell lines. METHODS: A total of 129 biopsy samples from the skin and oral mucosal lesions were tested immunohistochemically for COX-2 expression. Then the in vitro effects of nimesulide, ALA-based PDT, and their combination were determined on two SCC cell lines, HSC-2 and HSC-4. Three different methods (MTT assay, double-staining for annexin V and propidium iodide, caspase-3/CPP32 fluorometric protease assay) were applied for evaluation of their inhibitory effects on these two cell lines. RESULTS: Among the skin diseases, a considerable number of COX-2 high expressers were found in actinic keratosis (15 of 25, 60%), Bowen's disease (13 of 17, 76%) and extramammary Paget's disease (15 of 15, 100%). In contrast, only one of 33 (3%) basal cell carcinoma tumours was a COX-2 high expresser. Among the oral mucosal biopsies, the proportion of COX-2 high expressers increased gradually from hyperplasia (one of six, 17%) through mild dysplasia (five of eight, 63%) and moderate dysplasia (20 of 23, 87%) to severe dysplasia (two of two, 100%). Nimesulide had an inhibitory effect in vitro on HSC-2 (proven to be a COX-2 high expresser), but not on HSC-4 (a COX-2 non-expresser). While ALA-based PDT showed an inhibitory effect on both HSC-2 and HSC-4, most importantly the combination of nimesulide and ALA-based PDT demonstrated a significant synergistic effect on the cellular growth inhibition of only HSC-2, but not of HSC-4. CONCLUSIONS: Our study strongly suggests that COX-2 can be one of the molecular targets in treating various skin and oral diseases. The results from our in vitro experiments also prompt us to develop a new protocol with a combination of COX-2 selective inhibitor and ALA-based PDT for more effective treatment of those diseases.

Enfermedad de Bowen perianal / Perianal Bowen disease

Antecedentes: La Enfermedad de Bowen es un carcinoma intraepitelial, no queratinizado de células escamosas de la piel. La localización perineal es poco frecuente. Objetivos: Analizar su forma de presentación, el tratamiento implementado y los resultados obtenidos. Diseño: Trabajo retrospectivo. Población: Pacientes con Enfermedad de Bowen perianal asistidos en nuestro Hospital en los años 2000 y 2001. Método: En todos los casos el diagnóstico se realizó por biopsias de áreas condilomatosas; en 1 caso se realizó resección amplia de la lesión. Conclusiones: La escasa sintomatología de esta patología retrasan su diagnóstico. Ante su sospecha es fundamental el minucioso examen de toda la región anogenital y la biopsia de toda lesión sospechosa. En la actualidad el consenso general mantiene como tratamiento de elección a la resección ampliada. El curso clínico de la enfermedad de Bowen es relativamente benigno con un riesgo a desarrollar un carcinoma invasor que no supera el 2 al 6 por ciento. El seguimiento en el tiempo es imprescindible para prevenir recurrencias. (AU)

Immunohistochemical study of inducible nitric oxide synthase in skin cancers.

BACKGROUND: Nitric oxide (NO) is synthesized from the amino acid L-arginine by NO synthase (NOS). Experimental evidence suggests that increased express of inducible NOS (iNOS), which is an NOS isoform and calcium independent, is related to various pathological processes, such as inflammation and cancer. METHODS: In this study, we used immunohistochemistry to investigate iNOS expression in a series of basal cell carcinomas (BCC), Bowen's disease, squamous cell carcinomas (SCC), extramammary Paget's disease (EPD) and metastatic tumors of the skin. RESULTS: Only 1 of 16 BCC cases was positive for iNOS and the intensity of staining was weak. In most of the 10 cases of Bowen's disease, iNOS was weakly expressed and there was a wide range in the percentage of positive tumor cells. Twelve of the 16 cases of SCC were positive for iNOS and the extent of positivity was greater than in Bowen's disease. Two of the 7 cases of EPD were positive for iNOS, and 12 of the 15 cases of metastatic cancer were positive. Well-differentiated adenocarcinomas were diffusely positive, whereas poorly-differentiated ones showed strong and heterogeneous staining. CONCLUSIONS: These results indicated that the expression of iNOS may reflect the proliferation of tumor cells and that a heterogeneous distribution of iNOS may correlate with a wide variety of biological behavior of tumor cells.

Immunohistochemical expression of cyclooxygenase-2 in skin cancers.

BACKGROUND: Cyclooxygenase (COX), also known as prostaglandin endoperoxide synthase, catalyses the conversion of arachidonic acid to prostanoids. There are two different isoforms of COX, referred to as COX-1 and COX-2. Overexpression of COX-2 has been demonstrated in various neoplasms, such as experimentally promoted tumors, gastrointestinal cancers and breast tumors. METHODS: In this study, we used immunohistochemistry to investigate COX-2 expression in a series of basal cell epitheliomas (BCE), Bowen's disease, squamous cell carcinomas (SCC) and metastatic tumors of the skin. RESULTS: Four of 16 BCE showed a positive reaction for COX-2 and the adenoid type of BCE was the most strongly positive. In Bowen's disease, the extent of positive staining for COX-2 was even higher than that in BCE. Eleven of 15 SCC showed a positive reaction for COX-2 and the pattern of staining was heterogeneous with more intense staining in the center of the tumor nests. In metastatic tumors, the percentage of COX-2-positive tumor cells and the intensity of their staining was low compared with Bowen's disease and SCC. CONCLUSIONS: These results indicate that the intensity of COX-2 staining and its heterogeneous distribution are related to the degree of cellular differentiation and the various phenotypes of tumor cells, but the extent of COX-2 staining did not correlate with the degree of malignancy.

Cutaneous carcinomas and preinvasive neoplastic lesions. Role of MMP-2 and MMP-9 metalloproteinases in neoplastic invasion and their relationship with proliferative activity and p53 expression.

BACKGROUND: Metalloproteinases (MMPs) are thought to be involved in the process of destruction of basement membranes and stromal invasion by neoplastic epithelial cells. AIMS: In order to investigate the role of MMPs in cutaneous oncogenesis we studied the expression of MMP-2 and MMP-9 in 34 cases of epidermal preinvasive neoplastic lesions and invasive carcinomas. We also studied their relationship with the expression of tissue inhibitors of MMPs and with proliferative activity and p53 expression in neoplastic epithelial cells. RESULTS: MMP-9 was found to be focally expressed by neoplastic epithelial cells at the infiltrative edges in microinvasive carcinomas and in dyskeratotic foci in Bowen's disease and widely invasive carcinomas. Gradation of Mib-1 positivity and p53 expression was found with increasing abnormality in the spectrum of malignancy. CONCLUSIONS: Our results seem to suggest the involvement of MMPs in microinvasive carcinomas, which show also low proliferative activity and p53 expression, whether other factors seem to be more important in widely invasive carcinomas.

Immunohistochemical localization of ornithine decarboxylase in skin tumors.

BACKGROUND: Ornithine decarboxylase (ODC) plays an important role in the biosynthesis of polyamines. Induction of ODC and polyamine synthesis has been demonstrated in neoplastic tumors and is thought to be related to the degree of malignancy. METHODS: In this study, we investigated a series of basal cell epitheliomas (BCE), Bowen's disease, squamous cell carcinomas (SCC), and metastatic tumors of the skin using an antibody against ODC for immunohistochemistry. RESULTS: Eight of 12 cases of BCE failed to show a positive reaction for ODC. In Bowen's disease, 5 of 13 cases diffusely showed positive reaction for ODC. Fourteen of 15 cases of SCC showed ODC expression, the intensity of which was decreased in the peripheral layer. At higher magnification, the distribution of ODC in the positive SCC cases showed granular and heterogenous patterns. Ten of 14 cases of metastatic skin tumors exhibited positive reactions, and well-differentiated adenocarcinomas tended to show more strongly positive than poorly-differentiated ones. CONCLUSIONS: These results support the conclusion that the intensity and the incidence of positive immunohistochemical staining for ODC correlate with the degree of cellular differentiation, and furthermore, that heterogenous distribution of ODC staining may be associated with heterogeneity of tumor cells.

Cathepsin B and D expression in squamous cell carcinoma.

To elucidate involvement of proteinases in malignancy of keratinocytes, expression of cathepsin B, a cysteine proteinase, and cathepsin D, an aspartic proteinase, was ascertained in formalin-fixed paraffin-embedded specimens of normal skin, squamous cell carcinoma (SCC). Bowen's disease, seborrhoeic keratosis and basal cell carcinoma (BCC). Presence of procathepsin B and an intermediate form of cathepsin D was confirmed by Western blotting and enzyme activity analysis. Cathepsin B stained more intensely in SCC tumour cells than in normal epidermis; staining patterns were diffuse, granular or both. Diffuse and granular patterns (procathepsin B and mature enzyme, respectively) appeared in inner and outer parts of tumour islands, respectively. Five of 20 cases of Bowen's disease showed diffuse enhanced cathepsin B expression; 20 cases of seborrhoeic keratosis or BCC did not. Cathepsin D stained intensely in tumour cells of half the SCC cases. The staining manner and distribution of cathepsins B and D was similar in the cytoplasm of cancer cells. No enhanced staining of cathepsin D was seen in any cases of Bowen's disease, seborrhoeic keratosis, or BCC. Coexistence and localization of active mature forms of cathepsins B and D suggests that cooperation between the two enzymes may play an important part in invasion of SCC.

Immunolocalizations of human gelatinase (type IV collagenase, MMP-9) and TIMP (tissue inhibitor of metalloproteinases) in normal epidermis and some epidermal tumors.

The matrix metalloproteinases (MMPs) MMP-2 and MMP-9 (gelatinases) have been suggested as serving an important role in cleaving the basement membrane structure. Tissue inhibitors of metalloproteinases TIMPs (particularly TIMP-1) are known to inhibit MMPs. Based on this background, we raised monoclonal antibodies against human gelatinase (MMP-9) and human recombinant TIMP (TIMP-1), and immunostained these two components in skin from patients with squamous cell carcinoma (SCC), Bowen's disease (BD) and keratoacanthoma (KA). MMP-9 showed positive staining mainly in the granular layer of normal epidermis. In some cases of SCC and BD, MMP-9 showed positive staining in the dysplastic lesions even in the basal layer. TIMP showed a thorough positivity in normal epidermis. Unstained regions with this antibody were observed in SCC and BD. These results suggest that an altered staining pattern for MMP-9 and TIMP may be closely related to the malignant transformation of SCC and BD.

The expression of placental-type glutathione S-transferase (GST-pi) in human cutaneous carcinoma in situ, that is, actinic keratosis and Bowen's disease, compared with normal human skin.

The expression of human placental type glutathione S-transferase (GST-pi) was investigated in human cutaneous carcinoma in situ, that is, actinic keratosis and Bowen's disease, and compared with that in normal skin, using Northern blot and immunohistochemical analysis. In Northern blot examination, the expression of GST-pi transcript was recognized in all instances. Carcinoma in situ showed significantly higher expressions of GST-pi than normal skin. In the immunohistochemical examination, nuclear staining of GST-pi was noticed in some dysplastic cells of carcinoma in situ, especially in Bowen's disease. In actinic keratosis, a framework appearance was noticed in the staining pattern at a lower magnification because the lower part of the cytoplasm of dysplastic cells lining the stratum basale was positive for GST-pi, and all cells of the stratum granulosum and more cells of the stratum spinosum showed stronger GST-pi positive reaction than normal skin. In Bowen's disease, GST-pi positive, dysplastic cells existed throughout the epidermis. Because GST-pi positive, dysplastic cells and GST-pi positive, normal looking squamous cells made the GST-pi positive cell nests throughout the epidermis, and GST-pi positive, dysplastic cells, and GST-pi negative, normal looking cells coexisted in the parabasal layer, they showed a sawtooth appearance in the staining pattern at a lower magnification. These findings suggest that GST-pi is involved in the process of carcinogenesis.

Gamma glutamyl transpeptidase expression in foetal skin, inflammatory dermatoses and cutaneous neoplasia.

Gamma glutamyl transpeptidase (GGT) is an enzyme expressed by some epithelial neoplasms but not normal interfollicular epidermis. In order to examine the relationship between malignant change and de-differentiation we studied histochemically the expression of GGT in human foetal skin, various inflammatory dermatoses and epidermal neoplasms. In foetal skin GGT was detectable after 7 weeks' gestation, reached a maximum at 11 weeks and was undetectable by 24 weeks. It was expressed strongly by squamous cell carcinoma and focally in Bowen's disease and actinic keratoses. There was no GGT expression in basal cell carcinoma or most benign skin tumours, but keratoacanthomas were weakly positive. Keratinocytes in the vicinity of malignant melanocytes also expressed GGT. This study suggests that GGT expression, while not a simple marker of malignancy, may represent reversion to a less differentiated or 'foetal' phenotype.

Expression of glutathione S-transferase-pi in malignant skin tumors.

GST-pi has been known to be markedly increased in human (pre) neoplasms of several organs. In this paper, the significance of immunohistochemical detection of GST-pi in human malignant tumors of the skin was studied. In specimens from 40 patients with various skin cancers, malignant melanoma, Paget's disease and undifferentiated squamous cell carcinoma showed strong reactivity in GST-pi staining. The reactions were negative or weak in Bowen's disease, basal cell epithelioma and solar keratosis. In normal melanocytes, eccrine, apocrine, and breast gland cells stained positively but not in keratinocytes, sebaceus gland and fibroblasts. While immunohistochemical detection of GST-pi in the skin was not specific for malignancies, it contributed to aid the distinction of squamous cell carcinoma from other keratinocytic tumors. GST-pi might provide potentially useful information on chemosensitivity of skin cancer, and might serve as a biomarker of disease activity.

A quantitative histochemical study of three oxidative enzymes in solar keratoses and Bowen's disease.

Succinate dehydrogenase (SDH), glucose-6-phosphate dehydrogenase (G6PDH) and lactate dehydrogenase (LDH) activities have been studied using quantitative enzyme histochemical techniques in the epidermis of five patients with solar keratoses and Bowen's disease. 'Non sun-exposed' buttock skin was compared with the skin from the actual lesion and adjacent, clinically normal paralesional skin. SDH activity was significantly increased in the basal layer and decreased in the granular layer in the epidermis of both lesion and paralesional skin, although the total epidermal activities were unchanged when compared to 'non-exposed' buttock skin. G6PDH activity was increased in the granular layer of paralesional epidermis and of lesions. No change in LDH activity was detected. Inclusion of phenazine methosulphate in the reaction mixtures resulted in a three-fold increase in formazan deposition without altering the localization. It is concluded that the quantitative changes and alteration in localization of SDH and G6PDH reported in solar keratoses are accompanied by similar changes in adjacent, clinically normal 'sun-exposed' skin and differ from normal 'non-exposed' skin. It is suggested that these changes may precede the development of the solar keratoses and that these findings may indicate a significant metabolic alteration in the events that lead to neoplasia.