Nectins and nectin-like molecules (Necls) are calcium-independent immunoglobulin-like cell adhesion molecules with emerging roles in cancer biology, immune regulation, and targeted therapy. Their growing importance as therapeutic targets, immune checkpoint ligands, and predictive biomarkers across many tumour types has been described. NECTIN-1 functions as a major metastasis-suppressor gene in melanoma. NECTIN-1 is deleted in approximately 55% of melanomas, and its loss promotes IGF1-driven melanoma dissemination. Nectin-1 also serves as the entry receptor for oncolytic herpes simplex virus therapy (T-VEC, talimogene laherparepvec). Nectin-2/CD112 and Necl-5/CD155 are key T cell immunoreceptors with Ig and ITIM domains (TIGIT) and are CD226 immune checkpoint ligands. CD155 overexpression predicts resistance to anti-PD-1 therapy and poor prognosis in melanoma, non-small cell lung cancer (NSCLC), and small cell lung cancer (SCLC). Nectin-4 is an oncogenic driver (via PI3K/AKT and SOX-2) in lung cancer and BRAF-inhibitor-resistant melanoma, as well as a validated target of enfortumab vedotin in urothelial carcinoma. Necl-2/CADM1 acts as a tumor suppressor in melanoma and NSCLC, as it suppresses the epithelial-mesenchymal transition (EMT). Data on renal cell carci­noma remain limited. Nectins and Necls constitute a clinically significant protein family in oncology. Currently, Nectin-4 and CD155/TIGIT represent the most therapeutically actionable targets. Combination strategies targeting TIGIT (tiragolumab, ociperlimab, or vibostolimab) with PD-1/PD-L1 blockade are under investigation. Moreover, enfortumab vedotin, an antibody-drug conjugate (ADC) targeting Nectin-4-high tumors, is under investigation in many solid tumors.

Leber hereditary optic neuropathy (LHON) is primarily caused by pathogenic mitochondrial DNA (mtDNA) variants, most commonly the m.11778G>A variant in the MT-ND4 gene. The presence of this variant alone is insufficient to trigger disease symptoms, of which vision loss is the hallmark. Given the incomplete penetrance and inter-population variability in modifying factors, this study aimed to investigate two previously proposed genetic risk factors for LHON in the Polish population. Using quantitative PCR, we measured the mtDNA copy number in peripheral blood of affected and unaffected carriers of the m.11778G>A variant. In addition, we assessed the frequency of the PRICKLE3 c.157C>T variant in symptomatic, asymptomatic and control individuals using PCR-RFLP. Our results indicate that mtDNA copy number was not associated with LHON symptom manifestation in the Polish cohort under conditions tested, in contrast to previously reported associations in other populations. In addition, the PRICKLE3 c.157C>T variant was absent in our cohort, indicating that it is not a common modifier of LHON penetrance in the Polish population. These findings suggest that the incomplete penetrance of LHON in the Polish population may involve other modifying factors, such as yet unidentified nuclear DNA variants.

Senataxin, an RNA/DNA helicase, is a key protein providing genome stability and one of the best characterized R-loop-binding factors playing an important role in transcription and DNA repair processes. Pathogenic SETX gene variants cause autosomal recessive spinocerebellar ataxia with axonal neuropathy (AOA2, MIM #606002) and autosomal dominant juvenile amyotrophic lateral sclerosis (ALS4, MIM #602433), rare neurodegenerative disorders characterized by juvenile onset of progressive cerebellar ataxia, axonal sensorimotor peripheral neuropathy, combined upper and lower motor neuron symptoms, and increased serum alpha-fetoprotein (AFP; specific for AOA2). We report two cases of adult patients presenting with cerebellar syndrome, scanned speech, and exercise intolerance which started in the second/third decade of life and were followed by muscle weakness and impaired gait coordination. Whole exome sequencing (WES) was performed to analyze single nucleotide and copy number variants. A decreased coverage of a genomic region of around 16 kb on chromosome 9 (chr9:132,295,852–132,311,876), suggesting a deletion encompassing 5 exons of the SETX gene (exons 11–15, NM_015046.7) was observed. This homozygous SETX (9q34.13) deletion leads to a frame shift and consequently truncation of the helicase domain in the protein. Loss-of-function variants in the SETX gene are known to be pathogenic. Statistical analysis of NGS data from the Polish population identified a few heterozygous carriers, suggesting its region-specific origin.

Osteosarcoma (OSa) is the most prevalent primary malignant bone tumor in children and adolescents, characterized by complex genetic and epigenetic alterations. Traditional treatments face significant challenges due to high rates of drug resistance and lack of targeted therapies. Recent advances in microRNA (miRNA) research have opened new avenues for understanding and treating osteosarcoma. This review explores the many critical functions of miRNAs in osteosarcoma, particularly their potential for clinical use. The review highlights two key areas where miRNAs could be beneficial. Firstly, miRNAs can act as biomarkers for diagnosing osteosarcoma and predicting patient prognosis. Secondly, specific miRNAs can regulate cellular processes like proliferation, cell death, migration, and even resistance to chemotherapy drugs in osteosarcoma. This ability to target multiple pathways within cancer cells makes miRNA-based therapies highly promising. Additionally, though the interaction between miRNAs and circular RNAs (circRNAs) falls outside the scope of the paper, it has also been discussed briefly. While miRNA-based therapies offer exciting possibilities for targeting multiple pathways in osteosarcoma, challenges remain. Efficient delivery, potential off-target effects, tumor complexity, and rigorous testing are hurdles to overcome before these therapies can reach patients. Despite these challenges, continued research and collaboration among scientists, clinicians, and regulatory bodies hold the promise of overcoming them. This collaborative effort can pave the way for the development of safe and effective miRNA-based treatments for osteosarcoma.

Descriptions of somatic cell divisions were made as early as the eighteenth and nineteenth centuries with varying degrees of accuracy. In this paper, we would like to present a forgotten Polish scientist Waclaw Mayzel (1847–1916), who described somatic mitosis in the corneal epithelium of the frog in 1875 almost simultaneously with the recognized discoveries of animal mitosis by Otto Bütschli and plant mitosis by Eduard Strasburger.

Clear cell sarcoma (CCS), formerly called soft tissue melanoma, is a rare malignant soft tissue sarcoma (STS) characterized by a propensity for lymphatic spread and poor prognosis. Clear cell sarcoma can be distinguished by a t(12; 22) (q13; q12) translocation, which in addition to diagnostic implications may be important for targeted treatment in the future. Clear cell sarcoma occurs mainly on the extremities, most often the shin (in the feet and ankle area), in the tendons, and aponeurosis, often at a young age. Considering the significant ability to develop metastases to regional lymph nodes (about 30% of cases), a sentinel node biopsy (SLNB) should be considered in diagnosis, with possible subsequent radical lymphadenectomy (LND) in the case of metastases. Treatment of localized disease is limited to radical local excision with optional complementary radiotherapy. Due to the resistance to classical chemotherapy and the presence of characteristic molecular abnormalities, research focusing on the use of molecular targeted therapies in this group of cancers is ongoing. In clinical trials, MET inhibitors, and tyrosine kinase inhibitors (TKI) were evaluated. Clear cell sarcoma was also one of the subtypes of tumors assessed in the CREATE clinical trial with crizotinib and IMMUNOSARC with checkpoint inhibitors. However, a poor understanding of the biology and natural course of this sarcoma requires further research to develop an effective treatment and unify clinical guidelines.

Epithelioid sarcoma (ES) comprises two subtypes, distal and proximal. Initially, the distinction between these variants was based on tumor location, but subsequent research highlighted numerous functional differences between them. Proximal ES is distinguished by the molecular deletion of INI1, while classic ES is characterized by retained dysfunctional INI1 expression. Classic ES features elevated expression of GLI3, FYN, and CXCL12, along with overactive Notch/Hedgehog pathways and class 1 human leukocyte antigens (HLA). In contrast, proximal ES demonstrates MYC overexpression and upregulation of genes associated with the cell cycle, chromatin metabolism, and protein synthesis. The differences in clinical presentation underscore the necessity for tailored treatment approaches for each ES subtype. New therapeutic strategies are crucial, especially for the aggressive proximal variant. Tazemetostat, an oral selective inhibitor of the histone methyltransferase enhancer of zeste homolog 2 (EZH2), has recently gained FDA approval as a first-line treatment for ES patients.

Malignant peripheral nerve sheath tumor (MPNST) is an aggressive soft tissue sarcoma (STS); it originates from nervous tissue and typically develops in proximity to nerve trunks in the limbs and trunk. These tumors, constituting approximately 5% of soft tissue sarcomas, can either form spontaneously or arise from pre-existing neurofibromas. The majority (90%) of cases occur in individuals between the 2nd and 5th decades of life. The main risk factor for MPNST is von Recklinghausen disease (type 1 neurofibromatosis). The cornerstone of MPNST management involves radical surgical measures, specifically tumor excision within healthy tissue boundaries (wide local excision), which is complemented by adjuvant radiotherapy. In case of metastatic disease, palliative chemotherapy employing doxorubicin or a combination of doxorubicin and ifosfamide is utilized. Approximately 25-30% of patients experience clinical improvement after chemotherapy. Looking ahead, advancements in research on molecular biology may lead to the development of inhibitors demonstrating greater efficacy than traditional chemotherapy for MPNST patients. At present, ongoing clinical trials of the therapeutic management of MPNST encompass pembrolizumab, the combination of nivolumab with ipilimumab, pexydartinib (an inhibitor targeting KIT, CSF1R, and FLT3) in conjunction with sirolimus, sapanisertib (a TORC1/2 inhibitor), or LOXO-195 (an inhibitor of neurotrophic tyrosine kinase receptors NTRK type 1, 2, and 3).

Soft tissue sarcomas (STS) originating from connective tissue rarely affect the lymph nodes. However, involvement of lymph nodes in STS is an important aspect of prognosis and treatment. Currently, there is no consensus on the diagnosis and management of lymph node metastases in STS. The key risk factor for nodal involvement is the histological subtype of sarcoma. Radiological and pathological evaluation seems to be the most effective method of assessing lymph nodes in these neoplasms. Thus, sentinel lymph node biopsy (SLNB), which has been shown to be valuable in the management of melanoma or breast cancer, may also be a beneficial diagnostic option in some high-risk STS subtypes. This review summarizes data on the risk factors and clinical characteristics of lymph node involvement in STS. Possible management and therapeutic options are also discussed.

PEComa (PEC tumor; perivascular epithelioid cell tumors) is a rare group of tumors of mesenchymal origin composed of perivascular epithelioid cells (PEC) with features of melanotic and smooth muscle differentiation. In this article, we would like to present the current treatment options for this group of tumors. PEComas are classified as tumors of uncertain malignant potential because recurrences occur after radical treatment. The primary treatment is surgical resection with negative margins. Due to the different locations of the tumors, often the cooperation of multispecialty surgeons is required during the operations. In locally advanced cases, cytoreduction and HIPEC may be effective but still are an experimental treatment. For nonresectable PEComa chemotherapy, mTOR inhibitors and VEGFR inhibitors are used.

The TP53 gene is mutated in 50% of human tumors. Oncogenic functions of mutant TP53 maintain tumor cell proliferation and tumor growth also in osteosarcomas. We collected data on TP53 mutations in patients to indicate which are more common and describe their role in in vitro and animal models. We also describe animal models with TP53 dysfunction, which provide a good platform for testing the potential therapeutic approaches. Finally, we have indicated a whole range of pharmacological compounds that modulate the action of p53, stabilize its mutated versions or lead to its degradation, cause silencing or, on the contrary, induce the expression of its functional version in genetic therapy. Although many of the described therapies are at the preclinical testing stage, they offer hope for a change in the approach to osteosarcoma treatment based on TP53 targeting in the future.

Merkel cell carcinoma (MCC) is an uncommon and highly aggressive skin cancer. It develops mostly within chronically sun-exposed areas of the skin. MCPyV is detected in 60–80% of MCC cases as integrated within the genome and is considered a major risk factor for MCC. Viral negative MCCs have a high mutation burden with a UV damage signature. Aberrations occur in RB1, TP53, and NOTCH genes as well as in the PI3K-AKT-mTOR pathway. MCC is highly immunogenic, but MCC cells are known to evade the host’s immune response. Despite the characteristic immunohistological profile of MCC, the diagnosis is challenging, and it should be confirmed by an experienced pathologist. Sentinel lymph node biopsy is considered the most reliable staging tool to identify subclinical nodal disease. Subclinical node metastases are present in about 30–50% of patients with primary MCC. The basis of MCC treatment is surgical excision. MCC is highly radiosensitive. It becomes chemoresistant within a few months. MCC is prone to recurrence. The outcomes in patients with metastatic disease are poor, with a historical 5-year survival of 13.5%. The median progression-free survival is 3–5 months, and the median overall survival is ten months. Currently, immunotherapy has become a standard of care first-line therapy for advanced MCC.

Mitochondrial encephalomyopathies comprise a group of heterogeneous disorders resulting from impaired oxidative phosphorylation (OxPhos). Among a variety of symptoms progressive external ophthalmoplegia (PEO) seems to be the most common. The aim of this study is to present clinical and genetic characteristics of Polish patients with PEO. Clinical, electrophysiological, neuroradiological, and morphological data of 84 patients were analyzed. Genetic studies of mitochondrial DNA (mtDNA) were performed in all patients. Among nuclear DNA (nDNA) genes POLG was sequenced in 41 patients, TWNK (C10orf2) in 13 patients, and RNASEH1 in 2 patients. Total of 27 patients were included in the chronic progressive external ophthalmoplegia (CPEO) group, 24 in the CPEO+ group. Twenty-six patients had mitochondrial encephalomyopathy (ME), six patients Kearns–Sayre syndrome (KSS), and one patient sensory ataxic neuropathy, dysarthria, ophthalmoparesis (SANDO) syndrome. Genetic analysis of nDNA genes revealed the presence of pathogenic or possibly pathogenic variants in the POLG gene in nine patients, the TWNK gene in five patients and the RNASEH1 gene in two patients. Detailed patients’ history and careful assessment of family history are essential in the diagnostic work-up. Genetic studies of both mtDNA and nDNA are necessary for the final diagnosis of progressive external ophthalmoplegia and for genetic counseling.

Osteosarcoma (OS) is the most frequent primary bone cancer in children and adolescents and the third most frequent in adults. Many inherited germline mutations are responsible for syndromes that predispose to osteosarcomas including Li Fraumeni syndrome, retinoblastoma syndrome, Werner syndrome, Bloom syndrome or Diamond–Blackfan anemia. TP53 is the most frequently altered gene in osteosarcoma. Among other genes mutated in more than 10% of OS cases, c-Myc plays a role in OS development and promotes cell invasion by activating MEK–ERK pathways. Several genomic studies showed frequent alterations in the RB gene in pediatric OS patients. Osteosarcoma driver mutations have been reported in NOTCH1, FOS, NF2, WIF1, BRCA2, APC, PTCH1 and PRKAR1A genes. Some miRNAs such as miR-21, -34a, -143, -148a, -195a, -199a-3p and -382 regulate the pathogenic activity of MAPK and PI3K/Akt-signaling pathways in osteosarcoma. CD133+ osteosarcoma cells have been shown to exhibit stem-like gene expression and can be tumor-initiating cells and play a role in metastasis and development of drug resistance. Although currently osteosarcoma treatment is based on adriamycin chemoregimens and surgery, there are several potential targeted therapies in development. First of all, activity and safety of cabozantinib in osteosarcoma were studied, as well as sorafenib and pazopanib. Finally, novel bifunctional molecules, of potential imaging and osteosarcoma targeting applications may be used in the future.

Introduction: Synovial sarcoma (SaSy) is a high-grade, malignant soft tissue sarcoma (STS) accounting for 5–9% of STS. The aim of this study was to analyse outcomes of patients with localised SaSy treated in a single institution with a uniform neo- and adjuvant-combined therapy protocol. Methods: 171 patients with stage II/III SaSy were treated between 1997 and 2014. Chemotherapy consisted of 4 cycles of ifosfamide 12 g/m2 and two cycles of a doxorubicin-based regimen 75 mg/m2. With the exception of patients who underwent amputation, all patients received neoadjuvant radiotherapy. Results: Median age was 33 years (range 17–69). Tumours larger than 5 cm in size were found in 70% of patients. The 5-year overall survival (OS), local relapse-free survival (LRFS) and metastasis-free survival (MFS) rates were 75%, 80% and 60%, respectively. In multivariate Cox’s regression, age > 35 years, male sex, larger tumour size and histology other than monophasic were associated with worse OS. Conclusions: In adult patients with localised SaSy, long-term survival can be achieved in a significant proportion of cases with intensive combined therapy. The multivariate analysis identified age, sex, disease stage and histology subtype as independent prognostic factors of OS.

The common mutation BRAFV600 in primary melanomas activates the mitogen-activated protein kinase/extracellular-signal-regulated kinase (MAPK/ERK) pathway and the introduction of proto-oncogene B-Raf (BRAF) and mitogen-activated protein kinase kinase (MEK) inhibitors (BRAFi and MEKi) was a breakthrough in the treatment of these cancers. However, 15–20% of tumors harbor primary resistance to this therapy, and moreover, patients develop acquired resistance to treatment. Understanding the molecular phenomena behind resistance to BRAFi/MEKis is indispensable in order to develop novel targeted therapies. Most often, resistance develops due to either the reactivation of the MAPK/ERK pathway or the activation of alternative kinase signaling pathways including phosphatase and tensin homolog (PTEN), neurofibromin 1 (NF-1) or RAS signaling. The hyperactivation of tyrosine kinase receptors, such as the receptor of the platelet-derived growth factor β (PDFRβ), insulin-like growth factor 1 receptor (IGF-1R) and the receptor for hepatocyte growth factor (HGF), lead to the induction of the AKT/3-phosphoinositol kinase (PI3K) pathway. Another pathway resulting in BRAFi/MEKi resistance is the hyperactivation of epidermal growth factor receptor (EGFR) signaling or the deregulation of microphthalmia-associated transcription factor (MITF).