Expression of p-27 (kip1) in nevi and melanomas

Immunohistochemical characteristics of melanoma

Melanoma has a wide spectrum of histologic features which mimic epithelial, hematologic, mesenchymal, and neural tumors. Immunohistochemistry has been the primary tool to distinguish melanomas from these other tumors; it has also been studied for use as an adjunct to distinguish benign and malignant melanocytic tumors and to elucidate prognosis. Furthermore, there has been extensive effort to find a suitable marker to differentiate spindle cell and desmoplastic melanoma from other tumors. We have reviewed the literature investigating melanocytic differentiation markers, proliferation markers, immunomodulatory markers, signaling molecules, and nerve growth factors and receptors. Despite the proliferation of immunohistochemical markers, S-100 remains the most sensitive marker for melanocytic lesions, while markers such as HMB-45, MART-1/Melan-A, tyrosinase, and MITF demonstrate relatively good specificity but not as good sensitivity as S-100. No marker has proven useful in distinguishing spindle cell and desmoplastic melanomas from other tumors. Ki67 remains the most useful adjunct in distinguishing benign from malignant melanocytic tumors. None of the markers reviewed has been shown conclusively to have prognostic value for melanocytic neoplasms.

Expression of activated Akt in benign nevi, Spitz nevi and melanomas

BACKGROUND

Activated Akt expression (p-Akt) is reportedly increased in many melanomas as compared with benign nevi. The purpose of this study was to evaluate and compare p-Akt immunohistological staining in benign nevi, Spitz nevi and primary melanomas.

METHODS

Immunostaining for phosphorylated Akt was performed in 41 melanocytic lesions previously classified as benign intradermal nevus (14 lesions), Spitz nevus (9 lesions) or melanoma (18 lesions). Lesions were graded for intensity of p-Akt staining by two independent observers (0, no staining; 1, slightly positive; 2, moderately positive; 3, highly positive). Scores were averaged, and statistical analyses were performed.

RESULTS

Benign nevi showed less staining (mean score 1.18) compared with Spitz nevi (mean score 2.11) and melanomas (mean score 2.19). This difference was statistically significant between benign nevi and melanomas (p = 0.0047) and benign nevi and Spitz nevi (p = 0.0271). No statistical difference was detected in staining between Spitz nevi and melanomas (p = 0.8309).

CONCLUSIONS

Activated Akt expression is increased in Spitz nevi and melanomas as compared with benign intradermal nevi, but is unlikely to prove useful in differentiating between the former.

Cell cycle and apoptosis regulators in Spitz nevi: comparison with melanomas and common nevi

BACKGROUND

Deregulated cell cycle control is one of the hallmarks of tumor development. The expression of different cell cycle regulators has been used in various neoplasms as an adjunct to diagnosis.

OBJECTIVE

We sough to determine the expression of cell cycle and apoptosis regulators in Spitz nevi and to appraise its value as a diagnostic adjunct in the differential diagnosis from melanomas and common nevi.

METHODS

Ki-67, p-27, p-16, p-53, p-21, Rb, cyclin D1, cyclin A, cyclin B1, bcl-2, and bax expression was assessed by immunohistochemistry in 10 Spitz nevi and was compared with 16 melanomas and 20 common nevi immunohistochemical expression.

RESULTS

P-27 (60% +/- 20.13), p-16 (62.00% +/- 10.85), and bcl-2 (46.00% +/- 42.47) were highly expressed in Spitz nevi, whereas Ki-67 (2.80% +/- 2.55), Rb (3.75% +/- 4.55), p-53 (2.30% +/- 0.10), cyclin A (0.70% +/- 1.56), B1 (0.20% +/- 0.34), and bax (2.65% +/- 6.37) demonstrated a limited expression. Cyclin D1 (8.60% +/- 7.30) and p-21 (6.40% +/- 5.37) showed a moderate expression. The expression of bax (P = .001), Ki-67 (P < .0001), Rb (P < .0001), p-16 (P < .0001), cyclin A (P < .0001), and cyclin B1 (P < .0001) was significantly higher in melanomas in comparison with Spitz nevi, whereas p-27 expression was significantly higher in Spitz nevi (P < .0001). A trend for significant difference in favor of melanomas was also observed for p-53 (P = .002). On the other hand, no difference was detected for bcl-2 (P = .275), p-21 (P = .055), or cyclin D1 (P = .077). Spitz nevi demonstrated a trend for a higher expression for p-21 (P = .008) and cyclin D1 (P = .006), whereas they exhibited lower p-16 (P = .004) in comparison with common nevi.

LIMITATIONS

The number of Spitz nevi was relatively small.

CONCLUSION

Spitz nevi differ from melanomas in their immunohistochemical pattern of expression of cell cycle and apoptosis regulators and more closely resemble common benign nevi.

The role of cell cycle regulatory proteins in the pathogenesis of melanoma

The transformation of melanocytes to melanoma cells is characterised by abnormal proliferation resulting from alterations in cell cycle regulatory mechanisms. This occurs through alterations in the two major cell cycle regulatory pathways, the retinoblastoma (Rb) and p53 tumour suppressor pathways. This review summarises the current knowledge of alterations in these two pathways at G1/S transition and specifically the role of the key cell cycle regulatory proteins pRb, p16INK4a (p16), cyclin D1, p27Kip1 (p27), p53 and p21Waf1/Cip1 (p21) in the pathogenesis of melanoma. It also considers their prognostic significance. Current data indicate that alterations of cyclin kinase inhibitor (cdki) levels are implicated in the pathogenesis of melanoma and may be useful prognostic markers. However, large validation studies linked to comprehensive clinical follow up data are necessary to clarify the prognostic significance of cell cycle regulatory proteins in individual patients.

Pathologic Reporting and Special Diagnostic Techniques for Melanoma

Pathologists play a central role in the management of cutaneous melanoma in determining that a tumor is a melanoma, whether or not it is primary or metastatic, and whether or not the margins of excision are tumor free and in evaluating prognostic indicators from examination of the primary tumor and, where appropriate, lymph nodes, including the sentinel nodes.

De-regulation of ubiquitin-dependent proteolysis and the pathogenesis of malignant melanoma

Malignant melanoma is similar to the other types of cancer in terms that the pathogenesis of this lethal disease includes abnormal activation of proteins that mediate oncogenic signaling as well as inhibition of anti-proliferative and pro-apoptotic protein regulators. Activity of both types of cellular regulators is often dependent on their abundance and is determined by the rate of proteolysis via the ubiquitin pathway. Aberrations in ubiquitin-dependent degradation of regulatory proteins frequently occur in human cancers including malignant melanoma. Melanoma cells that re-program ubiquitin-dependent proteolysis toward accelerated degradation of protein regulators of tumor suppression and abnormal stabilization of oncogenic proteins are likely to gain an advantage in growth and survival. Specific characteristics of melanoma biology include rapid metastasizing and resistance to conventional anticancer therapy. Exploration of these traits should place an emphasis on a subset of the signal transduction pathways that are governed by a number of key protein regulators whose stability and activity becomes deregulated during progression of malignant melanoma. Targeting the ubiquitination and degradation of these pivotal proteins may provide a promising new therapeutic approach to treatment of this disease.

Skp2 and p27kip1 expression in melanocytic nevi and melanoma: an inverse relationship

BACKGROUND

S-phase kinase associated protein-2 (Skp2) ubiquitin ligase p45(SKP2) is important in the degradation of p27kip1 (a cyclin dependent kinase inhibitor) and progression through the G1-S cell-cycle checkpoint. Low levels of p27 and high levels of Skp2 are related to poor prognosis in some cancers.

METHODS

Clinicopathologic features and immunohistochemical expression of Skp2 and p27kip1 were investigated in 198 melanocytic proliferations: 21 melanocytic nevi, 23 melanoma in situ, 119 primary melanoma, and 35 metastatic melanoma samples. Comparative and survival analyses were performed.

RESULTS

Progressive and significant increases and decreases in the nuclear expression of Skp2 and p27kip1, respectively, was identified moving from melanocytic nevi (0.05 +/- 0.2/85 +/- 15) to melanoma in situ (3 +/- 2/45 +/- 20) to primary cutaneous melanoma (12 +/- 9/30 +/- 25) to metastatic melanoma (25 +/- 15/15 +/- 20) (p < or = 0.006). Expression of these proteins also significantly correlated with increasing American Joint Committee on Cancer (AJCC) T (tumor) classification and AJCC stage (p < or = 0.01). Moreover, the level of these two proteins exhibited a significant inverse relationship (r = -0.4, p = 0.0001). Skp2 cytoplasmic labeling index of >20% predicted worse 10-year overall survival (38% vs. 86%, p = 0.04) in primary melanoma. Neither p27 nor Skp2 nuclear expression impacted significantly on prognosis.

CONCLUSIONS

Gain of Skp2 and loss of p27kip1 protein expression are implicated in melanoma progression where the level of p27kip1 may be regulated by targeted proteolysis via Skp2. Cytoplasmic expression of Skp2 defines a subset of aggressive melanomas and could represent another pathway of deregulation of the cell cycle.

Hypoxia regulation of the cell cycle in malignant melanoma: putative role for the cyclin-dependent kinase inhibitor p27Kip1

BACKGROUND

Intratumor hypoxia has been shown to promote more aggressive and metastatic cancer phenotypes that are associated with treatment resistance and poor prognosis. Cellular proliferation and its control are known to be important components of tumor progression. Hypoxia induces cell-cycle arrest in cultured cell lines, possibly via up-regulation of the cyclin-dependent kinase inhibitor p27. The effect of hypoxia on cell-cycle regulation in excised human tumors has not been investigated.

METHODS

We performed immunohistochemistry for p27 and Ki-67 on 10 formalin-fixed paraffin-embedded metastatic melanomas, selected on the basis of histological evidence of zonal/geographic necrosis, adjacent to areas with viable perivascular tumor cells.

RESULTS

In the majority of cases, there was a significant increase in p27 staining in cells adjacent to necrotic areas compared to perivascular zones. An inverse staining pattern between Ki-67 and p27 was identified in these tumors. Tumors with no zonal increase in p27 staining demonstrated a diffuse pattern of staining for Ki-67 within tumor nests.

CONCLUSIONS

While increased cellular proliferation is a characteristic of cancer, subsets of human melanomas may retain the ability to regulate their rate of proliferation in response to changes in the tumor microenvironment. The hypoxia-mediated cell-cycle arrest (decreased Ki-67) in these tumors may be mediated by p27 up-regulation.

Expression of cell cycle inhibitor p27Kip1 and its inactivator Jab1 in melanocytic lesions

Decreased expression of p27 (a cyclin-dependent kinase inhibitor) is an adverse prognostic marker in a diverse array of human cancers. The purpose of this study was to investigate the expression of p27 and Jab1 (a protein involved in p27 degradation) in melanocytic lesions, and to identify their possible participation in melanoma progression. A tissue microarray was constructed using formalin-fixed, paraffin-embedded archival tissue blocks of 94 melanocytic lesions including 19 benign nevi, 21 dysplastic nevi, 23 melanomas, and 31 metastatic melanomas. The expression of p27 and Jab1 was evaluated by immunohistochemistry. The association between p27, Jab1, and clinicopathological parameters was analyzed using chi2 and Fisher's exact tests. Nonparametric Pearson's rank correlation was applied to evaluate the relationship between p27 and Jab1 expression. p27 was expressed in 15 (88%) nevi, 18 (95%) dysplastic nevi, 11 (50%) melanomas, and only in four (13%) of the metastatic melanomas (P<0.001). Jab1 was expressed in 14 (82%) standard nevi, 18 (95%) dysplastic nevi, 17 (77%) melanomas, and 16 (53%) of the metastatic melanomas (P<0.01). In metastatic melanomas, there was a negative correlation between p27 and Jab1 expression (r=-0.166). The low levels of p27 in primary and metastatic melanoma cases may explain the high proliferation rate of such lesions. Also, the relative high expression of Jab1 in metastatic melanoma, associated with low levels of p27, suggests that Jab1 may be involved in survival and proliferation of metastatic melanoma cells.

Loss of heterozygosity at 12p13 and loss of p27KIP1 protein expression contribute to melanoma progression

Little is known about the mechanisms causing p27KIP1 decrease in melanomas. Therefore, we performed loss of heterozygosity (LOH) analysis with polymerase chain reaction at seven different loci surrounding the p27KIP1/CDKN1B gene at 12p13 and direct DNA sequencing analysis of all exons. Furthermore, the immunohistochemical expression of p27KIP1 and Ki-67 was investigated. Only two mutations in the sequence of p27KIP1/CDKN1B were detected, but the number of tumours showing LOH at 12p13 increased significantly with the parameters of tumour progression (pT level, P=0.018; Breslow index, P=0.01; Clark level, P<0.001), with a more aggressive tumour growth (radial versus vertical growth, P=0.018) and tumour subtype (superficial spreading melanomas versus nodular melanomas versus metastases, P<0.001). p27KIP1 protein expression decreased with the Clark level ( P=0.026) and the pT level ( P=0.045). No correlation between LOH affecting 12p13 and p27KIP1 protein decrease in melanomas was stated. This does not exclude the participation of p27KIP1/CDKN1B in p27KIP1 protein decrease, since protein expression is regulated at various cellular levels; but it could also suggest that other tumour suppressors are situated in the same region as p27KIP1/CDKN1B. Taken together, our data shows that loss of p27KIP1 protein expression and LOH at 12p13 contribute to tumour progression in melanoma.

Microenvironmental regulation of proliferation in multicellular spheroids is mediated through differential expression of cyclin-dependent kinase inhibitors

Multicellular spheroids composed of transformed cells are known to mimic the growth characteristics of tumors and to develop gradients in proliferation with increasing size. This progressive accumulation of quiescent cells is presumably an active process that occurs in response to the microenvironmental stresses that develop within the three-dimensional structure, and, yet, little is known regarding either the signals that induce the cell cycle arrest or the molecular basis for the halt in proliferation. We have previously reported that regulation of cyclin-dependent kinase (CDK) inhibitors (CKIs) differs in monolayer versus spheroid cell culture. In this study, we have examined the expression of three CKIs in EMT6 mouse mammary carcinoma and MEL28 human melanoma spheroids, as a function both of spheroid size and of location within the spheroid. We report that expression of the CKIs p18(INK4c), p21(waf1/cip1), and p27(Kip1) all increase as the spheroid grows and develops a quiescent cell fraction. However, by examining protein expression in discrete regions of the spheroid, we have found that only p18(INK4c) and p27(Kip1) expression positively correlate with growth arrest, whereas p21(waf1/cip1) is expressed predominantly in proliferating cells. Further analysis indicated that, in the quiescent cells, p18(INK4c) is found in increasing association with CDK6, whereas p27(Kip1) associates predominantly with CDK2. In MEL28 cells, CDK2 activity is completely abrogated in the inner regions of the spheroid, whereas in EMT6 cells, CDK2 activity decreases in accordance with a decrease in expression. We also observed a decrease in all cell cycle regulatory proteins in the innermost spheroid fraction, including CDKs, CKIs, and cyclins. Induction of CKIs from separate families, as well as their association with distinct target CDKs, suggests that there may be multiple checkpoints activated to ensure cell cycle arrest in non-growth-conducive environments. Furthermore, because very similar observations were made in both a human melanoma cell line and a mouse mammary carcinoma cell line, our results indicate that these checkpoints, as well as the signal transduction pathways that activate them, are highly conserved.

Cell cycle in sporadic melanoma

Sporadic melanoma is a neoplasm whose etiology has not been fully investigated. Contemporary achievements in molecular biology have made it possible to localize the genes whose damage can contribute to the initiation of neoplastic transformation of melanocytes and lead to a progression of the disease. The majority of these genes are responsible for the correct progression of phase G1 of the cell cycle. Phase G1 of the cell cycle is subject to control by many protooncogenes and antioncogenes, which constitute the pRb or p53 pathway, damage to which can lead to the development of malignant melanoma. The present paper discusses disorders in the control of phase G1 of the cell cycle in sporadic melanoma.

Expression of p27kip1 in basal cell carcinomas and trichoepitheliomas

Immunohistochemical analysis was used to evaluate p27kip1 expression in normal hair follicles and in a series of 39 basal cell carcinomas (BCC) (13 of superficial type, 7 infiltrating, 7 morphea-like, 12 nodular) and 20 trichoepitheliomas (TE) (9 of classic type, 9 immature, 2 desmoplastic). The labeling index (LI) was derived semiautomatically by means of a computer-assisted cellular image analyzer, and statistical analysis was carried out using the Student t test. A positive reaction for p27kip1 was detected in the hair germ papillae, in supramatrical cells, and in the inner pilar sheath, whereas matrical cells and the outer pilar sheath were negative. All BCC and TE cases showed a positive immunoreaction for p27kip1, but the staining pattern was different in the two groups of lesions, being patchy with focal peripheral accentuation in TE and more diffusely dispersed in BCC. The quantitative study showed lower p27kip1 expression in BCC (LI = 27.51 +/- 12.55) than in TE (LI = 45.27 +/- 20.27) (P < 0.0001). Statistically significant differences were also observed between TE subgroups and nodular or infiltrating BCC subtypes. The occurrence of a wide overlap of LI values hampers the practical application of a p27kip1 LI in the differential diagnosis between BCC and TE in difficult cases, however.

Transcription factors and other dysregulated proteins in melanoma prognosis

Approximately one third of patients with cutaneous melanoma later develop a metastatic disease, having then an extremely poor rate of survival. Because of the highly unpredictable nature of melanomas, finding those patients who are likely to develop a metastatic disease and those patients who probably will survive is an ongoing challenge. The current "conventional" prognosticators, such as Breslow thickness, Clark level of invasion, and ulceration, cannot perfectly predict the clinical course of this disease at an individual level. Although the sentinel lymph node biopsy procedure and reverse transcription polymerase chain reaction techniques have significantly improved the staging of patients with melanoma, new molecular prognostic markers may help in selection of appropriate patients for strenuous adjuvant therapies and for randomized clinical trials. Furthermore, these markers also improve our basic understanding of the biology of cutaneous melanoma, potentially offering new targets for novel treatment strategies. This paper reviews the current literature on transcription factors and other dysregulated proteins involved in melanoma prognosis.

p27 immunostaining is related to prognosis in malignant mesothelioma

AIMS

To evaluate the prognostic value of the proliferation-associated antigen p27 in malignant mesothelioma.

METHODS AND RESULTS

Sections from 36 patients with malignant mesothelioma were immunohistochemically stained for the p27 antigen. The results were quantified by recording the proportion of positively stained nuclei and these data were tested for association with patient survival. p27 expression was also compared with tumour type, MIB-1 expression, apoptotic and mitotic indices. Patients with pleural malignant mesothelioma showing low p27 expression (< 53% of cells positive) survived for significantly shorter periods of time than those with high p27 expression (> or = 53% of cells positive) (P=0.04). The 50% survival time of subjects with low p27 was 4-6 months whereas for those with high p27 expression it was 10-11 months. There was no significant association between p27 expression and MIB-1, apoptotic or mitotic indices.

CONCLUSIONS

Low p27 expression in pleural malignant mesothelioma is associated with a significantly worse prognosis. p27 appears to be an independent prognostic variable which may be of value in counselling patients with malignant mesothelioma.

Analysis of G(1)/S checkpoint regulators in metastatic melanoma

We have analyzed the expression of the CDKN1A (p21(CIP1)), CDKN1B (p27(Kip1)), TP53, RB1 and MDM2 proteins and tumor cell proliferation by immunohistochemical staining in 59 cases of metastatic melanoma. The genomic status of the CDKN2A (INK4-ARF, p16/p14(ARF)), CDKN2B (p15) and CDKN2C (p18) genes was determined by PCR-SSCP (single-strand conformation polymorphism) in 46 of these cases. These results were correlated with various clinico-pathological parameters, including the outcome of combined chemoimmunotherapy. We found positive correlations between the expression of CDKN1A and MDM2 (r = 0.5063, P = 0.001), between the expression of CDKN1B and RB1 (r = 0.5026, P = 0.001), and between RB1 expression and tumor cell proliferation (0.5564, P<0.001). Two mutations in the CDKN2A (p16) gene were detected, including a novel base change AAC-->ATC (Asn to Ile) at codon 71, that also changes the codon 85 of the alternative reading frame gene p14(ARF) from CAA to CAT (Gln to His). Homozygous deletion at exon 2 of the CDKN2A (INK4-ARF) gene was detected in six cases. In seven cases, the 540C-->G polymorphism in the 3'UTR of the CDKN2A (p16) gene was found in linkage disequilibrium with the 74C-->A polymorphism in intron 1 of the CDKN2B gene (P < 0.0001). These cases had significantly lower expression of the TP53 protein (P = 0.0032). Both 540C-->G and 580C-->T polymorphisms in the 3'UTR of the CDKN2A (p16) gene were associated with significantly shorter progression time from primary to metastatic disease (P = 0.0071). We conclude, that although none of the analyzed cell cycle regulators could be singled out as a major prognostic factor, G(1)/S checkpoint abnormalities remain one of the most significant factors in the development of malignant melanoma.