As regards their morphology and biology, tumours consist of heterogeneous cell populations. The cancer stem cell (CSC) hypothesis assumes that a tumour is hierarchically organized and not all of the cells are equally capable of generating descendants, similarly to normal tissue. The only cells being able to self-renew and produce a heterogeneous tumour cell population are cancer stem cells. CSCs probably derive from normal stem cells, although progenitor cells may be taken into consideration as the source of cancer stem cells. CSCs reside in the niche defined as the microenvironment formed by stromal cells, vasculature and extracellular matrix. The CSC assays include FACS sorting, xenotransplantation to immunodeficient mice (SCID), incubation with Hoechst 33342 dye, cell culture in non-adherent conditions, cell culture with bromodeoxyuridine. CSCs have certain properties that make them resistant to anticancer therapy, which suggests they may be the target for potential therapeutic strategies.

ALCAM (activated leukocyte cell adhesion molecule, CD166, MEMD) is a transmembrane protein of immunoglobulin superfamily (Ig-SF) and plays an important role in human malignant melanoma progression and formation of locoregional and distant metastases. The study using melanoma cell lines showed that overexpression of ALCAM is directly related with the increase of cytoaggregation and the ability to form cell nests. The aim of the study was to assess the expression and intracellular localization of ALCAM in primary skin melanomas and metastatic lesions from regional lymph nodes. Also, prognostic significance of ALCAM expression in primary tumor cells and metastatic lesion cells was evaluated in the context of 5-year observation. Formalin-fixed paraffin-embedded tissue specimens from 104 primary cutaneous melanomas and 16 regional lymph nodes metastases were studied for the expression of ALCAM measured by immunohistochemistry. We demonstrate that high ALCAM expression in primary melanoma cells (IRS ≥8) is strongly correlated with unfavorable prognosis as compared with patients with lower ALCAM immunoreactivity in tumor compartment as regards cancer specific overall survival (CSOS) (P = 0.001) and disease free survival (DFS) (P < 0.001). Additionally lower ALCAM immunoreactivity in nodal metastatic foci was significantly statistically correlated with deeper melanoma invasion in the primary tumor according to Clark scale (P = 0.032). It was also found that decreased ALCAM expression (IRS <8) in nodal metastases shows a trend related with a correlation with shorter cancer specific overall survival (P = 0.083). Statistically significant correlations were also demonstrated between the presence of ulceration and decreased intensity of lymphocytic inflammatory infiltration and a high percentage of ALCAM-positive cells (P = 0.035, P = 0.01, respectively). High ALCAM expression in melanoma cells of the primary tumor can be used as a marker of negative outcome and may indicate a more invasive phenotype of cancer cells, which would require a more intensive therapeutic strategy. Low expression of ALCAM in regional lymph node metastases is a feature associated with unfavorable prognosis in patients with cutaneous melanoma. Our study is the first one to evaluate the effect of increased ALCAM expression on long-term survival in melanoma patients.

GOLPH2 and GOLPH3 are Golgi-related proteins associated with aggressiveness and progression of a number of cancers. Their prognostic significance in melanoma has not yet been analyzed. We performed immunohistochemical analysis for GOLPH2 and GOLPH3 in 20 normal skin, 30 benign nevi and 100 primary melanoma tissue samples and evaluated their expression in three compartments: cancer cells, tumor-associated macrophages (TAMs) and cancer-associated fibroblasts (CAFs). High levels of both proteins in melanoma cells were associated with characteristics of aggressive disease, and shorter disease-free survival (DFS) and cancer-specific overall survival (CSOS). On the contrary, increased numbers of GOLPH2-positive and GOLPH3-positive TAMs were observed in thinner, non-ulcerated tumors, with brisk lymphocytic reaction and absent lymphangioinvasion. Distant metastases were not observed among patients with high numbers of GOLPH2-positive TAMs. Increased expression of either protein in TAMs was related to prolonged CSOS and DFS. Similarly, GOLPH3-expressing CAFs were more frequent in thin melanomas with low mitotic rate, without ulceration and lymphangioinvasion. Moreover, increased GOLPH3-positive CAFs correlated with the absence of regional or distant metastases, and with longer CSOS and DFS. GOLPH2 expression was not observed in CAFs. Our results suggest that GOLPH2 and GOLPH3 play a role in melanoma progression and are potential targets for molecular-based therapies.

Polo-like kinase 1 (PLK1) is a serine-threonine kinase that plays a crucial role in the regulation of cell division. In addition, it acts as a modulator of the DNA damage response and as a novel factor in the maintenance of genome stability during DNA replication. The present study aimed to reveal the associations between PLK1 expression and clinicopathological features of patients with breast cancer (BC), particularly patient survival at 5-, 10- and 15-year follow-up. PLK1 expression was evaluated immunohistochemically in routine diagnostic tissue specimens from 83 patients treated radically for stage II BC. Kaplan-Meier analysis revealed a correlation between PLK1 overexpression and long-term survival. High PLK1 immunoreactivity was associated with shorter cancer-specific overall survival (CSOS) and disease-free survival (P=0.00001 and 0.00013, respectively). Multivariate analysis confirmed the negative prognostic significance of PLK1 overexpression for CSOS in all 83 patients (P=0.00030). Furthermore, analogous correlations were observed in both subgroups with and without nodal metastases (P=0.01400 and 0.01200, respectively). The present results indicate that PLK1 expression has a prognostic role in early BC. Immunohistochemical assessment of PLK1 reactivity may potentially become a qualifier for inclusion of PLK1 inhibitor therapy.

Introduction: Mucosal melanoma is rare and associated with poorer prognosis in comparison to conventional melanoma subtypes. Little is known about the prognostic significance as well as possible associations between PARP1 and immunologic response in mucosal melanoma. Methods: PARP1, PD-L1 and IDO1 immunostains were performed on 192 mucosal melanomas including 86 vulvar, 89 sinonasal, and 17 anorectal melanomas. Results: By Kaplan–Meier analyses, high PARP1 expression correlated with worse overall and melanoma-specific survival (log-rank p values = 0.026 and 0.047, respectively). Tumors with combined PARP1 and IDO1 high expression correlated with worse overall and melanoma-specific survival (p = 0.015, 0.0034 respectively). By multivariate analyses, high PARP1 expression remained a predictor of worse survival independent of stage. By Fisher’s exact test, high PARP1 expression correlated with highly mitogenic tumors (p = 0.02). High tumoral PD-L1 and IDO1 expression were associated with ulcerated primary tumors (p = 0.019, 0.0019, respectively). By linear regression analyses, correlations between PARP1 expression versus IDO1 expression (p = 0.0001) and mitotic index (p = 0.0052) were observed. Conclusion: Increased expression of PARP1 is an independent negative prognostic marker in mucosal melanomas. The association between PARP1 and IDO1 and their combined adverse prognostic role raise the potential of combined therapy in mucosal melanoma.