Decoding Metastasis: From Cell Death to Fusion in Cancer Progression.

Metastasis is one of the key concepts in modern oncology, which connects the movement of cancer cells in the body with changes in their characteristics and functions. The review examines the main aspects of metastasis, including theories, facts and discoveries that help to better understand this phenomenon and develop new approaches to its treatment. In this article, we also proposed the theory of cell fusion with the formation of hybrid cells as one of the factors of metastasis. We believe that the fusion of tumor cells with other types of motile cells (leukocytes and bone marrow progenitor cells) may represent an additional mechanism of tumor spread. Cells of bone marrow origin, including cells of the myeloid and macrophage lineages, are the best candidates for heterotypic fusion in regenerative conditions. Events such as cell fusion may play a role in tumor dedifferentiation and progression. We presented a number of arguments and data from our own research that speak in favor of the proposed theory. It should be noted that if the fusion of a normal cell with a tumor cell is one of the possible triggers of tumorigenesis and cancer spread, the mechanisms underlying this process may provide possible new targets for treatment. Therefore, their analysis will expand our arsenal of therapeutic tools by adding completely new targets - cell signaling molecules - and will provide the impetus for reconsidering the tumor microenvironment from a different angle.

Hybrid/Atypical Forms of Circulating Tumor Cells: Current State of the Art.

Cancer is one of the most common diseases worldwide, and its treatment is associated with many challenges such as drug and radioresistance and formation of metastases. These difficulties are due to tumor heterogeneity, which has many causes. One may be the cell fusion, a process that is relevant to both physiological (e.g., wound healing) and pathophysiological (cancer and viral infection) processes. This literature review aimed to summarize the existing data on the hybrid/atypical forms of circulating cancer cells and their role in tumor progression. For that, the bioinformatics search in universal databases, such as PubMed, NCBI, and Google Scholar was conducted by using the keywords "hybrid cancer cells", "cancer cell fusion", etc. In this review the latest information related to the hybrid tumor cells, theories of their genesis, characteristics of different variants with data from our own researches are presented. Many aspects of the hybrid cell research are still in their infancy. However, with the level of knowledge already accumulated, circulating hybrids such as CAML and CHC could be considered as promising biomarkers of cancerous tumors, and even more as a new approach to cancer treatment.

A review of surface-enhanced Raman spectroscopy in pathological processes.

With the continuous growth of the human population and new challenges in the quality of life, it is more important than ever to diagnose diseases and pathologies with high accuracy, sensitivity and in different scenarios from medical implants to the operation room. Although conventional methods of diagnosis revolutionized healthcare, alternative analytical methods are making their way out of academic labs into clinics. In this regard, surface-enhanced Raman spectroscopy (SERS) developed immensely with its capability to achieve single-molecule sensitivity and high-specificity in the last two decades, and now it is well on its way to join the arsenal of physicians. This review discusses how SERS is becoming an essential tool for the clinical investigation of pathologies including inflammation, infections, necrosis/apoptosis, hypoxia, and tumors. We critically discuss the strategies reported so far in nanoparticle assembly, functionalization, non-metallic substrates, colloidal solutions and how these techniques improve SERS characteristics during pathology diagnoses like sensitivity, selectivity, and detection limit. Moreover, it is crucial to introduce the most recent developments and future perspectives of SERS as a biomedical analytical method. We finally discuss the challenges that remain as bottlenecks for a routine SERS implementation in the medical room from in vitro to in vivo applications. The review showcases the adaptability and versatility of SERS to resolve pathological processes by covering various experimental and analytical methods and the specific spectral features and analysis results achieved by these methods.