Expression of proliferation markers and cell cycle regulators in T cell lymphoproliferative skin disorders

Cell adhesion molecule 1 expression in mycosis fungoides versus parapsoriasis versus inflammatory dermatosis: an immunohistochemical comparative study

Cell adhesion molecule 1 (CADM1) is one of the immunoglobulin super family adhesion molecules, that is proposed to contribute in the pathogenesis of various types of cutaneous T-cell lymphoma, including mycosis fungoides (MF). In this work, we decided to examine the immunohistochemical expression of CADM1 in MF specimens compared to premycotic parapsoriasis, benign inflammatory dermatosis and normal control skin specimens. 125 participants were enrolled (50 MF, 25 parapsoriasis, 25 inflammatory dermatosis, and 25 healthy controls). Patients were selected from the Outpatient Clinic of Dermatology and Venereology Department, Tanta University Hospitals. From all, 4 mm punch skin biopsies were taken and examined for CADM1 immunohistochemical expression. The current study revealed statistically significant upregulation of CADM1 expression in MF specimens in comparison to parapsoriasis, inflammatory dermatosis, and normal control specimens. Additionally, there was statistically significant positive correlation between CADM1 expression and progression of TNMB staging of MF disease. Therefore, it is possible to recommend CADM1 as a beneficial diagnostic immunohistochemical marker for differentiation between early stages of MF and both the premycotic parapsoriasis and benign inflammatory dermatosis. Moreover, it may be of value in early detection of neoplastic transformation of parapsoriasis as well as in assessment of MF progression.

Single-cell RNA sequencing of mycosis fungoides reveals a cluster of actively proliferating lymphocytes

A 70-year-old man's chronic erythematous skin lesion in the extremity had developed into a tumour one year before his first visit at our hospital. A biopsy showed atypical lymphocyte-like cells, and immunostaining identified atypical cells as CD3+, CD4+, CD5+ and FOXP3+. Single-cell RNA sequencing (scRNA-seq) analysis using BD Rhapsody revealed the higher expression of CD3, CD4, CD5 and FOXP3 genes in a group of cells that highly expressed genes, such as PCNA, in the S/M phase, which is in agreement with immunofluorescence staining results. The use of scRNA-seq analysis data is expected to promote personalised medicine for cutaneous lymphoma.

GOLPH3 inhibition reverses oxaliplatin resistance of colon cancer cells via suppression of PI3K/AKT/mTOR pathway

OBJECTIVE

To explore whether GOLPH3 regulated oxaliplatin (L-OHP) resistance of colon cancer cells via PI3K/AKT/mTOR pathway.

METHODS

HCT116/L-OHP cells were divided into Blank, Control/GOLPH3 shRNA, BEZ235 (a PI3K/AKT/mTOR inhibitor), and GOLPH3 + BEZ235 groups followed by the detection with MTT, soft agar colony formation, flow cytometry and TUNEL assays. Mice bearing HCT116/L-OHP xenografts were randomized into Control, L-OHP, NC/GOLPH3 shRNA, L-OHP + NC/GOLPH3 shRNA groups. The expressions of Ki67, Caspase-3, and PI3K/AKT/mTOR pathway proteins were examined by immunohistochemistry.

RESULTS

HCT116/L-OHP cells had increased GOLPH3 expression compared to HCT116 cells, which positively regulated PI3K/AKT/mTOR pathway in HCT116/L-OHP cells. BEZ235 declined IC50 of HCT116/L-OHP cells to L-OHP, decreased the expressions of ABCB1, ABCC1, ABCG2, ATP7A, ATP7B, MATE1, p-gp, MRP1 and BCRP, induced cell apoptosis, reduced cell proliferation, and arrested cells at G0/G1, which was reversed by GOLPH3 overexpression. L-OHP and GOLPH3 shRNA decreased tumor volume and reduced expression of Ki67 in tumor tissues with the increased Caspase-3. Meanwhile, the combined treatment had the better treatment effect.

CONCLUSION

GOLPH3 inhibition reduced proliferation and promoted apoptosis of HCT116/L-OHP cells, and also reversed the L-OHP resistance of HCT116/L-OHP, which may be associated with the suppression of P13K/AKT/mTOR pathway.

MicroRNA-93 Targets p21 and Promotes Proliferation in Mycosis Fungoides T Cells

BACKGROUND

Mycosis fungoides (MF), the most common form of cutaneous T-cell lymphoma (CTCL), is a lymphoproliferative disorder characterized by proliferation of malignant T cells in a chronic inflammatory environment in the skin. The nature of MF is still not fully understood, but aberrant microRNA (miR) expression and function seem to play an important role in the pathogenesis and disease progression and have been proposed as a putative disease marker. Recent studies have reported aberrant expression of miR-93 in situin MF lesions and linked dysregulated miR-93 expression to advanced stages of MF. However, the pathophysiological role of miR-93 in MF is unknown.

OBJECTIVE

Here, we provide the first evidence that miR-93 targets the cell cycle regulator cyclin-dependent kinase inhibitor p21 and promotes growth of malignant T cells in MF.

METHODS/RESULTS

Thus, inhibition of miR-93 in MF patient-derived malignant T-cell lines increases expression of p21 and inhibition of malignant proliferation. Notably, treatment with the histone deacetylase inhibitor Vorinostat (SAHA) reduces miR-93 expression and enhances p21 expression in the malignant T cells. Importantly, transfection with an miR-93 mimic partly blocks SAHA-induced p21 expression.

CONCLUSIONS

we provide evidence that enhanced expression of the putative oncogenic miR, miR-93, represses the cell cycle inhibitor p21 and promotes proliferation of malignant T cells. Moreover, we demonstrate that SAHA triggers p21 expression - at least partly - through an inhibition of miR-93.

Pre-clinical efficacy assessment of Malva sylvestris on chronic skin inflammation

In the search for improved quality of life, the treatment of skin diseases like psoriasis (hyperproliferative disease) is valid, since it causes huge social discomfort to the patient. In this context, earlier studies showed that Malva sylvestris L. has anti-inflammatory activity demonstrated by acute animal models of skin inflammation, becoming a promising target for further studies. The present investigation aimed to verify the effect of hydroalcoholic extract of M. sylvestris (HEMS) on the chronic inflammatory and hyperproliferative response caused by multiple applications of 12-O-tetradecanoylphorbol-13-acetate (TPA) on mouse ears. Topical application of HEMS reduced oedema, leukocyte migration (mono- and polymorphonuclear cells) and keratinocyte hyperproliferation, confirmed by histology and proliferating cell nuclear antigen (PCNA) immunostaining. It was found that the anti-inflammatory effects of the extract did not involve the glucocorticoid system, and its incubation with HaCaT keratinocytes caused low toxicity and reduced cell proliferation by apoptosis. Thus, HEMS proved to be effective as an anti-psoriatic therapy, with the ability to prevent keratinocyte hyperproliferation and with low toxicity by topical application.

Expression of Minichromosome Maintenance Proteins in Actinic Keratosis and Squamous Cell Carcinoma

Minichromosome maintenance (MCM) proteins are a group of proteins involved in DNA replication and cell-cycle regulation. Because they are associated with DNA through G1 into S phase, MCM proteins are potentially specific indicators of cell proliferation that could be valuable markers of dysplasia, and preinvasive and invasive malignant tumors. To analyze MCM protein expression patterns in actinic keratosis (AK), Bowen disease (BD), and cutaneous squamous cell carcinoma (SCC), we performed immunohistochemical staining of MCM2, -5, and -7 on tissue microarray blocks from 91 AK, 50 BD, and 174 SCC samples. The distribution and semiquantitatively assessed number of positive cells were analyzed in relation to the type of the lesion and the SCC prognostic parameters (grade, diameter, and thickness). Basal expression of all 3 proteins was observed more frequently in AK, whereas the distribution in BD was predominantly diffuse (P<0.001). All 3 proteins showed peripheral distribution in most well-differentiated SCC and diffuse distribution in poorly differentiated tumors (P<0.001). Using the 50% cut-off value, there was a statistically significant difference among AK, BD, and SCC (P<0.001). In addition, all MCM proteins showed highly significant differences (P<0.001) between well-differentiated SCC and both moderately and poorly differentiated SCC. The diffuse distribution and 50% cut-off value of positive cells revealed statistically significant associations of all MCM proteins with SCC thicker than 6 mm. Our results suggest a role for MCM proteins in the progression of in situ keratinocytic lesions and their association with high-risk features in SCC.

Correlation between levels of expression of minichromosome maintenance proteins, Ki-67 proliferation antigen and metallothionein I/II in laryngeal squamous cell cancer

MCM2, MCM3 and MCM7 are minichromosome maintenance proteins found in dividing cells and they play a role in DNA synthesis. Increased MCM expression level is observed in cells of different cancer types. Additionally, metallothioneins (MT-I/II) are involved in control of cell proliferation and differentiation and changes of their expression are observed in many types of cancer. Ki-67 is known cancer cell proliferation antigen currently used in prognostic evaluation. The study material consisted of 83 laryngeal squamous cell cancer (LSCC) cases and 10 benign hypertrophic lesions of larynx epithelium as a control group. For the present study, laryngeal cancer cell line HEp-2 and human keratinocytes were employed, and to evaluate expression of all the markers, immunohistochemical method (IHC), immunofluorescence (IF) and western blot analysis were used. Statistical analysis showed strong positive correlation between expression of MCM2, MCM3, MCM7 and Ki-67 antigen in LSCC. Additionally, moderate positive correlation was observed between MCM3 and MT-I/II expression. In cancer cells, the level of expression of MCM3, MCM2, MCM7 and Ki-67 markers was increasing with the grade of LSCC malignancy. IF and western blot analysis showed higher MCM2, MCM3, MCM7 expression in HEp-2 cells in comparison to their expression in keratinocytes. MCM proteins might be useful markers of cell proliferation in LSCC.

Mycosis fungoides with large cell transformation: clinicopathological features and prognostic factors

Large cell transformation of mycosis fungoides (MF-LCT) occurs in 20-50% of advanced MF, and is generally associated with poor prognosis, although some patients have indolent disease. We sought to identify clinicopathological prognostic factors in a large number of patients with MF-LCT.We identified patients with MF-LCT treated between 1991 and 2012 at a referral centre for cutaneous lymphoma. Clinical and pathological records, and histopathological slides were reviewed. Associations of clinicopathological variables with disease-specific survival were analysed.In 51 patients with MF-LCT, factors significantly associated with shorter survival were: age >60 years (25 versus 61  months, p = 0.01), stage III/IV (25 versus 44  months, p = 0.049), high serum lactate dehydrogenase (LDH; 24 versus 53  months, p = 0.007), absent papillary dermal involvement (8 versus 30  months, p = 0.008); follicular mucin at transformation (24 versus 42  months, p = 0.007); and the absence of fibrosis at transformation (21 versus 42  months, p = 0.03). Patients presenting with transformation at diagnosis had better survival than those who started with a small cell phenotype (p = 0.02). Age >60 years was independently associated with poorer survival (HR 5.61, 95%CI 1.17-26.8, p = 0.03), and the presence of fibrosis at transformation was independently associated with improved survival (HR 0.30, 95%CI 0.09-0.97, p = 0.045).In patients with MF-LCT, clinical features (age, stage, serum LDH) are important in assessing prognosis. Additional clinical and pathological features identified in this study may also assist in prognostic stratification. Studies of larger cohorts should be performed to validate the prognostic significance of these features.

Immunohistochemistry method and diagnostics of mycosis fungoides

Clinical patient examinations are not enough for diagnosing lymphoproliferative skin diseases now. Histological diagnostics is an important auxiliary method; however, it is not always applicable. PCR is not a universal method for determining the clonality of infiltrate cells. The article describes present-day diagnostics methods with an emphasis on the immunohistochemistry method making it possible to identify the cell composition of affected skin.

SATB1 overexpression promotes malignant T-cell proliferation in cutaneous CD30+ lymphoproliferative disease by repressing p21

Cutaneous CD30(+) lymphoproliferative disease (CD30(+)LPD), characterized by the presence of CD30(+) anaplastic large T cells, comprises the second most common group of cutaneous T-cell lymphoma (CTCL). However, little is known about the pathobiology of the CD30(+) lymphoma cells, as well as the mechanisms of disease progression. Here we report that Special AT-rich region binding protein 1 (SATB1), a thymocyte specific chromatin organizer, is over-expressed in CD30(+) lymphoma cells in most CD30(+)LPDs, and its expression is upregulated during disease progression. Our findings show that SATB1 silencing in CD30(+)LPD cells leads to G1 cell cycle arrest mediated by p21 activation. Using chromatin immunoprecipitation, luciferase assays, and mutational analysis, we demonstrate that SATB1 directly regulates the transcription of p21 in a p53-independent manner. Moreover, DNA demethylation on a specific CpG-rich region of the SATB1 promoter is associated with the upregulation of SATB1 during disease progression. These experiments define a novel SATB1-p21 pathway in malignant CD30(+) T lymphocytes, which provides novel molecular insights into the pathogenesis of CD30(+)LPDs and possibly leads to new therapies.

Level of the proliferative activity of lymphocytes in case of mycosis fungoides and plaque parapsoriasis

The level of the proliferative activity is an important predictor of a number of oncologic diseases; at the same time, its diagnostic value for mycosis fungoides was not adequately investigated. Goal. To study the proliferative activity of lymphocytes in the skin of patients suffering form mycosis fungoides and plaque parapsoriasis. Materials and methods. The level of CD3+ and Ki-67+ cells was determined in skin biopsy samples taken from patients suffering from mycosis fungoides (18 subjects) and plaque parapsoriasis (6 subjects) by means of immunohistochemistry. The epidermal to dermal skin cell proliferative activity ratio (Ki-67+) and cell proliferative activity index were calculated. The control group comprised 16 healthy people. Results. The epidermal to dermal skin cell proliferative activity ratio amounted to 10.9 in healthy people, 5.43 in patients suffering from plaque parapsoriasis, and 3.84 and 2.42 in patients suffering from mycosis fungoides, spotty and plaque and tumor stages, respectively. The percentage of proliferative CD3+Ki-67+ cells relative to the total number of T-lymphocytes amounted to 1% in the patients suffering from plaque parapsoriasis and 3% in the patients with mycosis fungoides, spotty stage. Conclusion. The epidermal to dermal skin cell proliferative activity ratio (Ki-67+) in patients suffering from mycosis fungoides at any stage is lower than that in healthy subjects and patients suffering from parapsoriasis. The cell proliferative activity index was higher in the patients with mycosis fungoides, plaque and tumor stage, than in the patients with parapsoriasis. The number of CD3+Ki-67+ cells was higher in the patients with mycosis fungoides, spotty and plaque and tumor stages, than in the healthy subjects and patients suffering from parapsoriasis.

Simvastatin ointment, a new treatment for skin inflammatory conditions

BACKGROUND

Statins represent a class of drugs that effectively lowers cholesterol, however they also possess pleiotropic effects, like promotion of angiogenesis, prevention of bone loss, immunomodulatory and anti-inflammatory effects.

OBJECTIVES

Thus, the aim of this study was to investigate the activity of simvastatin topically applied in mice in acute and chronic skin inflammation models.

METHODS

Skin inflammation was induced in mice ears by topical application of 12-O-tetradecanoylphorbol acetate (TPA). In the acute model, ear oedema was measured by the increase of ear thickness 6h after TPA (2.5μg/ear). The chronic inflammatory process was induced by multiple applications of TPA (2.0μg/ear) for nine alternate days, and the oedema was measured daily as the increase in ear thickness.

RESULTS

Topical treatment was applied immediately after TPA in acute model or started at 5th day of chronic experiment. For acute model treatment was simvastatin (0.24, 0.71 and 2.40μM), dexamethasone (0.13μM), both in acetone or vehicle alone (acetone). In chronic model simvastatin (1% and 3%) and dexamethasone (0.5%) were incorporated in ointment preparations, and a group received ointment alone (vehicle). Samples of ear tissue (6mm) were taken from acute and chronic models, weighted and prepared for histological analysis and myeloperoxidase (MPO) enzymatic activity evaluation. Application of simvastatin in acetone reduced the ear oedema after a single TPA application in a dose dependent manner [ID(50) of 0.47 (0.22-1.13) μM], and the MPO enzymatic activity up to 61±10%. Also, both simvastatin ointment preparations 1% and 3% reduced acute TPA-induced ear oedema in 55±7% and 65±8%, respectively. In the chronic model, simvastatin ointment 1% was able to reduce ear oedema (25±3%) and ear weight (10±1%), though 3% formulation augmented both parameters. Histological analysis revealed a reduction of swelling and leukocyte migration in the acute model for both the formulations of simvastatin (1% and 3%), while in chronic model simvastatin 1% decreased ear swelling and epidermal thickness, but simvastatin 3% increased both parameters.

CONCLUSION

The results confirm the anti-inflammatory activity of simvastatin when applied topically in both acute and chronic models of skin inflammation. Besides, the formulation of simvastatin ointment 1% shows to be a very effective formulation for a chronic usage.

miRNA expression profiling of mycosis fungoides

MicroRNAs (miRNAs) are small RNA species that regulate gene expression post-transcriptionally and are aberrantly expressed in many malignancies including lymphoma. However, the role of miRNAs in the pathogenesis of T-cell lymphoid malignancies is poorly understood. Previously we examined the miRNA profile of Sézary syndrome (Sz), a leukemia of skin-homing memory T cells. In this study we determined the complete miRNome of mycosis fungoides (MF), the most common type of cutaneous T cell lymphoma. The miRNA profile of skin biopsies from 19 patients with tumor stage MF and 12 patients with benign inflammatory dermatoses (eczema and lichen planus) were compared by microarray analysis. We identified 49 miRNAs that are differentially expressed in tumor stage MF compared to benign inflammatory dermatoses using ANOVA analysis (P < 0.05, Benjamini-Hochberg corrected). The majority of the differentially expressed miRNAs (30/49) were up-regulated in tumor stage MF. The most significant differentially expressed were miR-155 and miR-92a (both up-regulated in tumor stage MF), while miR-93 showed the highest up-regulation in tumor stage MF with a fold difference of 5.8. Differential expression of a selection of these miRNAs was validated by miRNA-Q-PCR on additional test groups (tumors and controls). None of the miRNAs up-regulated in tumor stage MF was previously shown to be up-regulated in Sz, and only 2 of the 19 miRNAs down-regulated in tumor stage MF were also down-regulated in Sz. Taken together this report is the first describing the miRNA signature of tumor stage MF.

The role of immunohistochemical analysis in the diagnosis of parapsoriasis

Parapsoriasis is a chronic dermatosis whose biological distinction from early mycosis fungoides, the most frequent form of cutaneous T-cell lymphoma, is still not clearly defined. Two types of parapsoriasis have been delineated: large-plaque parapsoriasis and small-plaque parapsoriasis. The lack of clinical and histological features, which may allow distinguishing parapsoriasis from early mycosis fungoides has prompted several investigations to assess the role of immunohistochemistry in establishing a conclusive diagnosis of these conditions. However, the additional data obtained by immunohistochemical analysis concerning the CD4/CD8 ratio, the aberrant expression of T-cell antigens and the expression of proliferation markers has not generally helped establish a more definitive diagnosis. This review critically discusses these immunohistochemical markers and their use in diagnosis of parapsoriasis.

Minichromosome maintenance protein expression according to the grade of atypism in actinic keratosis

The minichromosome maintenance (MCM) family is a group of proteins that are key initiation factors for DNA replication and are expressed only in cycling cells. Recent studies on various cancerous conditions have shown that MCM proteins are better markers for malignant cells compared to other proliferative markers. It has been also proven that MCM proteins are independent prognostic factors. The aim of this study was to characterize the pattern and frequency of MCM 2 protein expression in actinic keratosis (AK) and determine whether the expression is correlated with the degree of histological atypism. Biopsy samples of 34 patients who had been diagnosed as AK were used in this study. Samples were divided into three groups (grade I, grade II, and grade III) according to the degree of atypism. Immunohistochemical staining for MCM 2 protein, Ki-67, and proliferating cell nuclear antigen was performed, and the number of positively staining cells per unit area (10⁻⁴ μm²) was calculated for evaluation of immunoreactivity. MCM 2 protein was expressed in atypical keratinocytes in AK. Mean numbers of immunoreactive cells positive for MCM 2 were 165.1 in grade I, 304.5 in grade II, and 513.3 in grade III. Moreover, the correlation between the immunoreactivity for MCM 2 protein and AK grade was significantly more positive than that for other markers. Thus, we suggest that MCM 2 protein is a reliable marker for diagnosing and grading AK and further could be hypothesized as an important prognostic factor.

Immunocytochemistry and the diagnosis of cutaneous lymphoma

Cutaneous lymphoid infiltrates may pose some of the most difficult diagnostic problems in dermatopathology. Immunocytochemistry is often employed in an effort to determine whether an infiltrate is neoplastic or, in the case of clearly malignant infiltrates, to provide a specific diagnosis. The rarity of these disorders and the variant immunocytochemical profiles they may present further thwart understanding and sometimes prevent an accurate diagnosis. In this review the common immunocytochemical profiles of various cutaneous lymphomas are presented and potential pitfalls and problems considered. Immunocytochemistry is not a diagnostic test but, as in other areas of histopathology, is a highly valuable tool that requires critical interpretation within a context: so applied, it is an indispensable part of the pathologist's arsenal in evaluating lymphoid infiltrates and defining different lymphomas.

CD30 expression and proliferative fraction in nontransformed mycosis fungoides

The major differential diagnosis for a primary cutaneous T-cell lymphoproliferative disorder with CD30 (Ki-1) positivity includes primary cutaneous anaplastic large cell lymphoma, lymphomatoid papulosis, pagetoid reticulosis and transformed mycosis fungoides (MF). Little is known, however, about CD30 expression in nontransformed MF, whether it simply reflects the proliferative fraction and if either CD30 staining or the proliferative fraction are of prognostic significance. Therefore, 47 nontransformed MF biopsies were stained for CD30 and Ki-67. The proportions of positive cells were determined and correlated with each other as well as with age, stage at diagnosis, maximum stage and survival. All cases had at least rare dermal CD30-positive cells. Higher percentages of dermal CD30 and Ki-67-positive cells were associated with a higher stage at diagnosis, and together with epidermal CD30, associated with a higher maximum stage. The proportion of CD30 and Ki-67-positive cells did not correlate with each other. Survivals were shorter if the dermal CD30 or epidermal or dermal Ki-67% were greater than the median (4.7%, 14%, 13%) and in patients of greater than or equal to 60 years of age or with a high stage. Dermal Ki-67 as a continuous variable was an independent prognostic indicator (P<0.001), as were dermal Ki-67 (P=0.004) and dermal CD30 (P=0.027) when analyzed as dichotomous variables but not stage. Therefore, CD30 expression is not restricted to transformed MF but higher levels of dermal CD30 expression and, even more so, dermal Ki-67 levels are independent adverse prognostic indicators.

Minichromosome maintenance proteins are useful adjuncts to differentiate between benign and malignant melanocytic skin lesions

BACKGROUND

Markers identifying premalignant and malignant melanocytic skin lesions are needed.

OBJECTIVE

We aimed to investigate the protein expression of minichromosome maintenance (MCM) proteins in melanocytic skin lesions with different malignant potential.

METHODS

Paraffin-embedded sections of benign melanocytic nevi (BN, n = 37), dysplastic nevi (DN, n = 25), and primary superficial spreading (SSM, n = 58) were assessed. Immunohistochemistry was performed for Ki-67, MCM3, MCM4, and MCM7 antibodies.

RESULTS

Ki-67 expression of SSM was significantly increased when compared to DN (P = .0001) and BN (P = .0015). Compared to BN and DN, expression of MCM3 was significantly increased in SSM (P < .0001 and P = .019, respectively). MCM3 expression of DN was significantly increased as compared to BN (P = .0067). There was a significant correlation between MCM3 expression and Breslow tumor thickness (r = 0.44, P = .019). In SSM, MCM4 expression was significantly increased when compared with DN (P < .0001) and BN (P = .0033). MCM4 immunoreactivity was significantly higher in DN than in BN (P = .016). Immunohistology of MCM7 did not reveal significant differences between the groups investigated (P = .48). However, immunoreactivity of MCM7 significantly correlated with Breslow tumor thickness and Clark level (r = 0.39, P = .023; r = 0.44, P = .010, respectively).

LIMITATIONS

Limitations of our study include the absence of survival data, mRNA results, and functional studies.

CONCLUSIONS

MCM3 as well as MCM4 are differentially expressed in BN, DN, and SSM. Hence, immunolabeling of MCM3 and MCM4 proteins appears to be a promising additive tool for distinguishing benign from malignant melanocytic skin lesions.

Expression of minichromosome maintenance proteins in Merkel cell carcinoma

OBJECTIVE

Minichromosome maintenance (MCM) nuclear proteins have barely been employed in the diagnosis of skin malignancies. We aimed to assess whether MCM immunohistochemistry can be utilized to examine tumour proliferation in Merkel cell carcinoma (MCC).

METHODS

In this pilot study, we studied skin specimens of eight patients with MCC. As a control, eight patients with cutaneous malignant melanoma (MM) were included. Immunohistochemistry was performed for MCM4, MCM6, MCM7, Ki-67, p53, and p21.

RESULTS

Protein expression of MCM4 (66.0 +/- 26.5% vs. 33.9 +/- 22.4%; P = 0.017), MCM6 (70.9 +/- 11.9 vs. 31.7 +/- 22.7; P = 0.0031), and MCM7 (76.5 +/- 16.4% vs. 34.9 +/- 25.5%; P = 0.0013) was significantly increased in tumour cells of MCC when compared to tumour cells of MM. Ki-67 immunoreactivity was also significantly higher in MCC than in MM (28.7 +/- 7.9 vs. 11.0 +/- 9.2; P = 0.0012). Immunolabelling of p53 (68.6 +/- 26.2 vs. 58.4 +/- 28.8; P = 0.46) and p21 (40.1 +/- 38.8 vs. 25.8 +/- 16.1; P = 0.35) was relatively high but not significantly increased in MCC when compared to MM.

CONCLUSION

Our preliminary data indicate that MCM immunohistochemistry may be a useful tool for the determination of tumour cell proliferation in MCC.