Breast cancer is the most common cancer and the leading cause of cancer death in woman of childbearing age. Tumor progression depends on the character of stromal-parenchymal interactions. Tumor microenvironment exerts a key influence on tumor progression. Tumor niche is an important element of the tumor microenvironment. According to existing ideas, tumor niche consists on immune cells and bone marrow progenitor cells. The present study describes the parameters of tumor niche in invasive breast carcinoma of no special type (IC-NST), associated with lymph node metastases. The purpose of the study was to investigate the features of tumor niche cell composition in IC-NST. Material and methods. The study included 128 patients with IC-NST (T1–3N0–3M0), who underwent total mastectomy or partial mastectomy with axillary lymph node dissection. The age of the patients ranged from 29 to 90. Histological examination of surgical specimens was carried out in accordance with standard methods. Suspensions of fresh frozen tumor surgical specimens were prepared for the hematopoetic progenitor cells identification. The antibodies against CD34, CD133, CD90, CD11B, CD45, AND CD202 were applied. Results. The study showed that the total number of hematopoietic stem and progenitor cells and macrophage progenitor cells in an amount exceeding 1.24 cells per 100 tumor cells was associated with the risk of developing lymph node metastases and large tumor size. Conclusion. The results obtained may be useful for understanding the role of tumor niche in tumor growth and lymph node metastasis of IC-NST.

Background: Testicular toxicity following chemotherapy is of increasing importance with the continuous improvement of survival rates. Gonadotropin-releasing hormone (GnRH) was suggested to protect testis against such toxicity; however, its suppressive quality and mechanism of action are still unclear. We examined whether and how pretreatment with GnRH antagonist protects against the testicular damage caused by chemotherapy. Methods: Mature male mice were injected subcutaneously eight times in 2-day intervals with either saline or GnRH antagonist (Cetrotide; 1 g/mg), followed by an intraperitoneal injection with either saline or cyclophosphamide (CTX;100 mg/kg BW) and sacrificed 2 weeks or 3 months later. Testicular weight, epididymis weight, epididymal sperm count and sperm motility were measured. Serum anti-Müllerian hormone (AMH) was measured by enzyme-linked immunosorbent assay. Immunohistochemistry (Ki-67), immunofluorescence (PCNA, CD34), terminal transferase-mediated deoxyuridine 5-triphosphate nick-end labeling (TUNEL) and computerized analysis were performed to examine testicular proliferation, apoptosis and vascularization. Quantitative real-time PCR was used to assess the amount of spermatogonial reserve (Id4 and Gfra1 mRNAs). Results: Pretreatment with GnRH antagonist transiently reduced testicular weight, epididymal weight, germinal proliferation and sperm count; it also abolished the permanent long-term effect of CTX on these parameters and prevented cyclophosphamide-induced testicular toxicity characterized by apoptosis and serum AMH increase and irreversible loss of spermatogonial reserve. Conclusions: Our findings imply that pretreatment with GnRH antagonist temporarily reduces spermatogenesis and may be used as pretreatment for reducing chemotherapeutic testicular toxicity.

Drug resistance represents one of the greatest challenges in cancer treatment. Cancer stem cells (CSCs), a subset of cells within the tumor with the potential for self-renewal, differentiation and tumorigenicity, are thought to be the major cause of cancer therapy failure due to their considerable chemo- and radioresistance, resulting in tumor recurrence and eventually metastasis. CSCs are situated in a specialized microenvironment termed the niche, mainly composed of fibroblasts and endothelial, mesenchymal and immune cells, which also play pivotal roles in drug resistance. These neighboring cells promote the molecular signaling pathways required for CSC maintenance and survival and also trigger endogenous drug resistance in CSCs. In addition, tumor niche components such as the extracellular matrix also physically shelter CSCs from therapeutic agents. Interestingly, CSCs contribute directly to the niche in a bilateral feedback loop manner. Here, we review the recent advances in the study of CSCs, the niche and especially their collective contribution to resistance, since increasingly studies suggest that this interaction should be considered as a target for therapeutic strategies.