Preferentially expressed antigen in melanoma (PRAME) is considered a useful marker in the differential diagnosis between malignant melanoma and its melanocytic mimics. Recently PRAME expression was documented in nonmelanocytic tumors, but much of the data are based on mRNA studies. This investigation evaluated PRAME expression in the spectrum of normal tissues and >5800 human tumors using immunohistochemistry and EP461 monoclonal antibody. In normal tissues, PRAME was expressed in the testis and proliferative endometrium. In tumors, PRAME was variably expressed in malignancies of different lineages. Among epithelial tumors, >50% of PRAME-positive lesions were found among endometrial carcinomas (82%), uterine serous carcinomas (82%), uterine carcinosarcomas (60%), ovarian clear cell carcinomas (90%), ovarian serous carcinomas (63%), adenoid cystic carcinomas (81%), seminomas (78%), thymic carcinomas (75%), and basal cell carcinomas (62%). In mesenchymal and neuroectodermal malignancies, PRAME was frequently expressed in synovial sarcoma (71%), myxoid liposarcoma (76%), neuroblastoma (61%) and metastatic melanoma (87%). Also, PRAME was consistently expressed in 4 melanomas that lacked all melanoma markers including S100 protein and SOX10 but harbored typical for melanoma BRAF or NRAS driver mutations. However, strong and diffuse PRAME immunoreactivity was seen in many types of nonmelanocytic poorly differentiated carcinomas and sarcomas. Based on this study, PRAME is a relatively unspecific immunohistochemical marker, which limits its use in diagnostic surgical pathology. However, immunohistochemistry is a reliable and unexpensive method useful in detecting PRAME-positive malignancies for potential immunotherapy.

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.

The presence of ulceration has been considered as one of the most important primary tumor characteristics of cutaneous malignant melanoma (CMM) for predicting patient outcome. Yet recently, scientific attention has been drawn towards another microscopic feature of primary tumors, the mitotic rate (MR). The present study aimed to examine the relationship between the presence of ulceration and the mitotic rate and clinicopathological characteristics and melanoma patient survival, and to discuss the results in the context of AJCC melanoma staging recommendations. Tissue samples were obtained from 104 patients treated for CMM. In classical H&E staining, the mitotic rate and the presence of ulceration were evaluated. Non-mitogenic tumors were defined as having 0 mitoses/mm2, low mitogenic potential, 1-2 mitoses/mm2 and highly mitogenic tumors, ≥3 mitoses/mm2. In the entire group of 104 patients, a high mitotic rate (hMR) and ulceration were highly negative prognostic factors, and indicated considerably shorter overall survival, cancer-specific overall survival and disease-free survival. Notably, hMR appeared to have a statistically significant negative impact on survival in early melanomas in both the pT1 (P=0.001) and pT2 subgroups (P=0.006). Kaplan‑Meier analysis of the remaining subsets (pT3 and pT4) did not reveal any important differences in the 5-year survival with regard to MR values. The presence of ulceration also had a prognostic significance for early melanomas, but only for pT1 tumors (P=0.05). Multivariate analysis confirmed that hMR was strongly associated with an unfavorable prognosis. Ulceration had no prognostic significance in the Cox proportional hazards model. Considering the biology of melanoma, hMR seems to be a more reliable parameter than the presence of ulceration. The value of MR categorizes melanomas into tumors with low or high proliferative potential, thus giving direct information concerning their capacity to infiltrate deeper layers of the dermis and, potentially, to generate regional lymph node and distant metastases.

Schlafen 11 (SLFN11), a DNA/RNA helicase, acts as a regulator of cellular response to replicative stress and irreversibly triggers replication block and cell death. Several preclinical in vitro studies and clinical trials established that SLFN11 expression predicts outcomes in patients with advanced cancer treated with DNA-damaging chemotherapeutics and more recently with poly(ADP-ribose) polymerase inhibitors. SLFN11 expression status remains unknown in many cancer types, especially in mesenchymal tumors. This study evaluated a cohort of well characterized 3808 epithelial and 2850 mesenchymal and neuroectodermal tumors for SLFN11 expression using immunohistochemistry. Nuclear SLFN11 expression was rare in some of the most common carcinomas, for example, hepatocellular (1%), prostatic (2%), colorectal (5%), or breast (16%) cancers. In contrast, other epithelial tumors including mesotheliomas (92%), clear cell renal cell carcinomas (79%), small cell lung cancers (76%), squamous cell carcinomas of the tonsil (89%) and larynx (71%), or ovarian serous carcinomas (69%) were mostly SLFN11-positive. Compared with epithelial malignancies, SLFN11 expression was overall higher in neuroectodermal and mesenchymal tumors. Most positive entities included desmoplastic small round cell tumor (100%), Ewing sarcoma (92%), undifferentiated sarcoma (92%), solitary fibrous tumor (91%), dedifferentiated liposarcoma (89%), synovial sarcoma (86%), and malignant peripheral nerve sheath tumor (85%). Also, this study identifies tumors with potentially worse response to DNA-damaging drugs including antibody drug conjugates due to the absence of SLFN11 expression. Such entities may benefit from alternative treatments or strategies to overcome SLFN11 deficiency-related drug resistance. Our approach and results should serve as a foundation for future biomarker-associated clinical trials.

Forkhead box P3 (Foxp3)⁺ T regulatory (Treg) cells are powerful controllers of the immune response and their role in the human immune system is indispensable. Since a number of revolutionary and very convincing results were brought to light, Foxp3 has unquestionably been thought to be the “master regulator” of Treg lineage commitment. Herein, we depict the revised view on the role of Foxp3 transcription factor, challenging this theory, as well as the growing significance of Runt-related transcription factor (RUNX) family proteins for Treg lineage. The review presents the current notion of Treg cell heterogeneity, molecular characteristics and their mechanisms of action.