Apoptosis and cellular proliferation in human epidermal squamous cell neoplasia

Phenol peels as a novel therapeutic approach for actinic keratosis and Bowen disease: prospective pilot trial with assessment of clinical, histologic, and immunohistochemical correlations

BACKGROUND

Although chemical peels may be used for precancerous lesions, no histologic or immunohistochemical studies have been performed to validate clinical impressions and/or outcome.

OBJECTIVE

Our purpose was to investigate the efficacy and prognostic relevance of phenol peels in Japanese patients with actinic keratosis and Bowen disease using clinical and histologic criteria.

METHODS

A total of 46 patients were treated with phenol peels, and followed up for at least 1 year after treatment. Biopsy specimens were taken before and after treatment. Cases of complete response were classified by the number of treatment sessions. We evaluated parameters for epidermal thickness, proliferation, dysplasia, and apoptosis, and clinical characteristics to correlate phenol peels with assessments of efficacy, patient-selection criteria, and risk for transformation to cutaneous squamous cell carcinoma.

RESULTS

There were 39 (84.8%) patients with a complete response after one to 8 treatment sessions. Statistically, differences in clinical improvement with peels and the number of treatment sessions correlated with histology, personal history of skin cancer, tumor thickness, and cyclin A expression.

LIMITATIONS

This study was a prospective pilot trial. Blinded, placebo-controlled, randomized studies would be ideal.

CONCLUSION

We conclude that phenol peels are very effective for treating precancerous lesions of actinic keratosis and Bowen disease. In addition, our study clearly demonstrates that tumor thickness and cyclin A could be specific and useful markers as adjunctive diagnostic tools to predict the efficacy of phenol treatment of these lesions.

E2F7 can regulate proliferation, differentiation, and apoptotic responses in human keratinocytes: implications for cutaneous squamous cell carcinoma formation

The E2F family of transcription factors plays a crucial role in the regulation of genes involved in cell proliferation, differentiation, and apoptosis. In keratinocytes, the inhibition of E2F is a key step in the control and initiation of squamous differentiation. Because the product of the recently identified E2F7a/E2F7b gene has been shown to repress E2F-regulated promoters, and to be abundant in skin, we examined its role in the epidermis. Our results indicate that E2F7b mRNA expression is selectively associated with proliferation-competent keratinocytes. Moreover, E2F7 was able to antagonize E2F1-induced proliferation and apoptosis. In contrast, although E2F7 was able to inhibit proliferation and initiate differentiation, it was unable to antagonize the differentiation suppression induced by E2F1. These data indicate that E2F7-mediated suppression of proliferation and apoptosis acts through E2F1-dependent pathways, whereas E2F7-induced differentiation acts through an E2F1-independent pathway. These data also suggest that proliferation, differentiation, and survival of primary human keratinocytes can be controlled by the relative ratio of E2F1 to E2F7. Because deregulated proliferation, differentiation, and apoptosis are hallmarks of cancer, we examined the expression levels of E2F1 and E2F7 in cutaneous squamous cell carcinomas (CSCC). We found that both genes were overexpressed in CSCCs compared with normal epidermis. Furthermore, inhibition of E2F7 in a SCC cell line sensitized the cells to UV-induced apoptosis and doxorubicin-induced apoptosis. Combined, these data suggest that the selected disruption of E2F1 and E2F7 in keratinocytes is likely to contribute to CSCC formation and may prove to be a viable therapeutic target.

Apoptosis and anti-apoptotic heat shock proteins in canine cutaneous infundibular keratinizing acanthomas and squamous cell carcinomas

Cell stress and death are linked in the neoplastic process, and heat shock proteins appear to play an important role by inhibiting apoptotic pathways. The apoptotic rates in 9 canine infundibular keratinizing acanthomas (IKAs) and 17 canine squamous cell carcinomas (SCCs) were correlated with the immunohistochemical expression of caspase-3 and the antiapoptotic heat shock proteins Hsp27, 72 and 73. Apoptosis was evaluated using the terminal deoxynucleotidyl transferase biotin-dUTP nick end labelling (TUNEL) method. The absence of a correlation between the TUNEL index and active-caspase-3 expression, a paucity of active-caspase-3-positive cells and Hsp72 over-expression were considered to be indicative of inhibition of apoptosis, and suggestive that inhibition of cell death plays a key role in oncogenesis and tumour growth of some canine skin neoplasms.

Expression of cell cycle and apoptosis regulatory proteins in keratoacanthoma and squamous cell carcinoma

Some authors view keratoacanthoma (KA) as a variant of squamous cell carcinoma (SCC), while others consider it a separate entity that must be distinguished from SCC. Involution displayed by KA is an important difference between these two entities. It has been suggested that apoptosis plays a role in the involution process of KA, although the exact trigger for it remains unclear. A hundred and fifty specimens were included in this study, 30 cases for each of the following groups: normal skin (NS), proliferative keratoacanthoma (pKA), regressing keratoacanthoma (rKA), well-differentiated squamous cell carcinoma (wdSCC), and poorly differentiated squamous cell carcinoma (pdSCC). They were immunohistochemically examined for the expression of p53, Ki-67, bak, and bcl-2. Significantly higher p53 and Ki-67 expressions were observed in all tumor lesions examined as compared with NS. There was higher bak expression in KAs compared to NS and a significant reduction of bak expression in pdSCC together with a significant reduction of bak expression in SCCs compared to pKA. Bcl-2 expression was similar in NS and SCCs, but was lower in rKA. We found a significant positive correlation between p53 and Ki-67, p53 and Bak in NS and examined skin tumors. Lower bcl-2 expression in conjunction with higher bak expression in rKA suggests a possible role of these apoptosis-regulating proteins in tumor regression. In contrast to this finding, a steady level of bcl-2 expression in pdSCC combined with lower bak expression levels and a high proliferation rate could contribute to progression and aggressiveness in these tumors. Bak and p53 expression is a sun-related and age-dependent process in NS and skin tumors.

Immunohistochemical studies of epithelial cell proliferation and p53 mutation in bovine ocular squamous cell carcinoma

Bovine ocular squamous cell carcinoma (OSCC) is the second most common cause of rejection due to neoplasia in slaughterhouses on Sao Miguel Island, Azores, and accounts for significant economic losses. To obtain a better insight into the genesis and neoplastic transformation process of bovine OSCC, abnormal protein expression and proliferation index were assessed by the immunohistochemical evaluation of p53 and Ki67, respectively. OSCC samples were collected from 15 bovines and were classified histologically according to the degree of differentiation into three categories: poorly, moderately, and well differentiated. Immunohistochemistry using polyclonal anti-human p53 antibody and polyclonal anti-human Ki67 antibody was performed. Ten of 15 tumors tested were immunoreactive for p53. Twelve tumors demonstrated Ki67 expression. As in human squamous cell carcinoma, p53 overexpression is frequent in bovine OSCC, providing support for a possible role of the protein in the pathogenesis of this neoplasia. No correlation between the percentage of p53 stained nuclei and the degree of differentiation was observed, although different patterns of staining were seen according to the degree of keratinization of the tumor cells. With the exception of the moderately differentiated OSCC group, Ki67 index showed significant correlation with the histologic pattern, increased proliferation being found in poorly differentiated OSCC (P = 0.013).

Squamous cell carcinoma in situ of the skin: History, presentation, biology and treatment

Squamous cell carcinoma in situ (SCCIS) of the skin is a problem commonly dealt with by dermatologists. The classic presentation, originally described by Bowen, is easily recognized, but presentation on some anatomical surfaces may be associated with less than typical features. Major aetiological factors for this disease are UV light, human papillomavirus infection and immunosuppression. The natural course of SCCIS is usually prolonged, with treatment being appropriate, but not urgent. The choice of therapy requires consideration of the location of the lesion, and a desire for a high cure rate without causing loss of form, function or cosmesis. The immunomodulatory agent imiquimod has offered a significant advance for the topical treatment of SCCIS. Our improved understanding of the underlying biology of SCCIS permits us to make rational choices of treatment. In the future we may be able to determine which of these lesions may progress to invasive disease, and help us select the most effective therapy.

Clinicopathological significance of tissue homeostasis in Indian breast cancer

BACKGROUND

Tissue homeostasis and the maintenance of cell populations depend on a delicate balance between the rates of cell proliferation and cell death. Disruption of this balance is an important factor in development and progression of tumors. In the present study we evaluated the growth index in a large group of breast cancer patients and correlated it with various clinical and histopathological features of the tumor.

METHODS

Estimation of apoptosis was determined by TUNEL assay while immunocytochemistry for proliferating nuclear cell antigen (PCNA) was used as a measure of proliferation. Necrosis was identified morphologically by haematoxylin and eosin staining.

RESULTS

A positive correlation was observed between the percentage of PCNA positive cells and the frequency of mitosis (r=0.6117, p<0.0001). A highly statistical significant correlation was observed between type of tissue analyzed and growth index (r=0.46869, p<0.0001). No significant association was observed between hormone receptor status and growth index.

CONCLUSIONS

The growth index was found to be higher in carcinoma cells that metastasised into lymph nodes compared with primary lesions with no nodal metastasis. Growth index was particularly prominent in high-grade tumors in which increased proliferative activity was evident. Apoptotic cells were detected more frequently in tumor cells with higher rather than lower proliferative activity. This suggests that not only proliferative activity but also capacity for apoptosis is altered in breast tumors.

Differential expression of proliferation- and apoptosis-related markers in lentigo maligna and solar keratosis keratinocytes

Keratinocytes influence the number, morphology, and proliferation of melanocytes. An interference in the melanocyte-keratinocyte relationship may contribute to melanoma development. This study examined the expression of apoptotic and proliferative markers in keratinocytes in lentigo maligna to characterize the epidermis permissive to these lesions. Formalin-fixed and paraffin-embedded tissues from 25 samples of lentigo maligna, 20 samples of solar keratoses, and 5 samples each of normal sun-exposed and non-sun-exposed skin (controls) were immunostained with antibodies directed against the proapoptotic markers bax and p53, the antiapoptotic marker bcl-2, and the proliferation marker ki-67. Eight percent of the lentigo maligna samples were positive for keratinocyte expression of bcl-2, 24% were positive for p53, and 76% were positive for bax; respective findings for solar keratoses were 35%, 85%, and 90%. Comparison with normal sun-exposed skin yielded lower rates of keratinocyte proliferation in 56% of the lentigo maligna samples, similar rates in 36%, and higher rates in 8%; for solar keratoses, proliferation was higher than controls in 60% of samples, similar in 35%, and lower in 5%. All these differences were statistically significant. These findings indicate that there are variable patterns of epidermal reaction to chronic sun exposure. The epidermis in lentigo maligna shows overall low proliferation and an apparently low apoptotic tendency. The dysfunctional epidermis may be permissive to aberrant melanocyte proliferation in the early stages of melanoma development.

Epidermal expression of serine protease, neuropsin (KLK8) in normal and pathological skin samples

AIMS

The expression of human neuropsin (KLK8) mRNA in normal and pathological skin samples was analysed and the results compared with those for tissue plasminogen activator (tPA) mRNA.

METHODS

Northern blot and in situ hybridisation analyses of KLK8 mRNA in normal and lesional skin of patients with cutaneous diseases were performed.

RESULTS

A weak signal for KLK8 mRNA and no signal for tPA mRNA was seen in normal skin on northern blot analysis. Weak signals for KLK8 were localised to the superficial cells beneath the cornified layer in normal skin on in situ hybridisation. Psoriasis vulgaris, seborrheic keratosis, lichen planus, and squamous cell carcinoma skin samples, which show severe hyperkeratosis, displayed a high density of KLK8 mRNA on northern and in situ hybridisation analyses. The signals were localised in granular and spinous layers of lesional skin in all hyperkeratic samples, including the area surrounding the horn pearls of squamous cell carcinoma. To examine the relation between mRNA expression and terminal differentiation, the expression of KLK8 mRNA was analysed in cell cultures. When keratinisation proceeded in high calcium medium, a correlative increase in the expression of KLK8 mRNA was observed.

CONCLUSION

The results are consistent with a role for this protease in the terminal differentiation of keratinocytes.

Fas-mediated apoptosis of melanoma cells and infiltrating lymphocytes in human malignant melanomas

In a rodent system, melanoma cells expressing Fas ligand (FasL) could kill Fas-positive lymphocytes, suggesting that FasL expression was an essential factor for melanoma cell survival in vivo. These findings led us to investigate apoptosis, and to histochemically analyze involvement of Fas and FasL in the induction of apoptosis, in human malignant melanoma tissues. The percentages of terminal deoxynucleotidyl transferase-mediated biotin-dUTP nick end-labeling (TUNEL)-positive melanoma cells and of proliferating cell nuclear antigen (PCNA)-positive melanoma cells in melanoma tissues (n = 22) were greater than those in melanocytes in uninvolved skin (n = 6) and nevus cells in nevi tissues (n = 9). The infiltrating lymphocytes around melanomas were also TUNEL positive. Immunohistochemistry revealed expression of Fas and FasL in melanoma cells and lymphocytes, whereas no Fas or FasL expression was detected in normal skin melanocytes and nevus cells. There was significant correlation between Fas-positive indices and TUNEL indices in melanoma tissues. Moreover, TUNEL-, Fas-, and FasL-positive indices of melanoma cells from patients with Stage 3 melanomas were significantly lower than those with Stage 2 melanomas. The PCNA index of Stage 1 melanoma was significantly lower than that of the other stages, although the difference of PCNA index was insignificant among Stages 2 to 4. Among Stages 1 to 4, there was no difference in the PCNA, TUNEL-, and Fas-positive indices of lymphocytes, although the FasL-positive index of lymphocytes from Stage 3 melanomas was significantly lower than in that from Stage 2. These data reveal that melanoma cells and infiltrating lymphocytes have the potential to induce their own apoptosis regulated by Fas and FasL in an autocrine and/or paracrine fashion and that the decline of Fas-mediated apoptosis of melanoma cells, rather than the apoptosis of infiltrating lymphocytes, may affect the prognosis of melanoma patients, possibly through the accumulation of more aberrant cells acquiring metastatic activity.

A study of apoptosis in Merkel cell carcinoma: an immunohistochemical, ultrastructural, DNA ladder, and TUNEL labeling study

We performed immunohistochemical, ultrastructural, terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick-end labeling (TUNEL), and DNA ladder studies of apoptosis in nine cases of Merkel cell carcinoma (MCC). None of the cases showed spontaneous regression as has been reported in several MCCs. Neuron-specific enolase was demonstrated by immunohistochemistry (8/8 MCCs), and staining for cytokeratin 20 was positive (2/8 MCCs). Ultrastructural examination revealed many cytoplasmic dense-cored granules, desmosome-like structures, and intermediate filaments. The granules were seen along the plasma membrane or around perinuclear centrioles. We found various stages of development of apoptotic bodies. Apoptosis resulted in vacuolization and fragmentation of nuclei and phagocytosed bodies in tumor cells. Apoptotic cells were also detected by TUNEL, DNA ladder, and immunostaining using the antibody against Fas (Apo- 1/CD95) antigen. It seems that a high apoptotic rate is a common finding in MCC, although spontaneous regression is an exceedingly rare event. It is thus unlikely that apoptosis alone would explain spontaneous regression.

Pre-operative radio-chemotherapy enhances apoptotic cell death in oral squamous cell carcinoma

The effect of pre-operative radio-chemotherapy (RCT) has been examined in a total of 15 oral squamous cell carcinomas (SCCs), in terms of apoptosis (cell loss) and proliferation. All the patients received pre-operative radiation at a dosage of 30 or 40 Gy, as well as anticancer agents including tagaful (FT), 5-fluorouracil (5-FU), bleomycin (BLM) and peplomycin (PEP). Surgical specimens were obtained before and after RCT, and serial sections were prepared for immunohistochemistry for p53 oncoprotein and Ki-67 antigen, as well as for terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL). TUNEL indices (TI; percentage of TUNEL-positive cells in the tumor cells) before and after RCT were 1.2+/-1.1 and 4.7+/-2.9 in the nine well-differentiated oral SCCs, and 1.0+/-0.7 and 3.9+/-2.1 in the six poorly differentiated SCCs, respectively. Similarly, Ki-67 indices (KI; percentage of Ki-67 antigen-positive cells in tumor cells) before and after RCT were 31.1+/-14.2 and 15.8+/-11.1 in the former, and 37.1+/-7.8 and 8.7+/- 13.4 in the latter, respectively. Thus, pre-operative RCT enhanced apoptotic cell death and abated proliferative activity significantly (P<0.05), regardless of histological differentiation. Enhancement of apoptosis was more prominent in the group treated with FT or 5-FU than with BLM or PEP. Oral SCC with >20% of nuclear p53-positive tumor cells was noted in six cases. Enhanced TI and abadement of KI did not differ among the p53-positive and -negative tumors.