Aided by extensive protein mutations, the SARS-CoV-2 Omicron (B.1.1.529) variant overtook the previously dominant Delta variant and rapidly spread around the world. It was shown to exhibit significant resistance to current vaccines and evasion from neutralizing antibodies. It is therefore critical to investigate the Omicron mutations trajectories. In this study, a literature search of published articles and SARS-CoV-2 databases was conducted, We explored the full list of mutations in Omicron BA.1, BA.1.1, BA.2, and BA.3 lineages. We described in detail the prevalence and occurrence of the mutations across variants, and how Omicron differs from them. We used GISAID as our primary data source, which provides open access to genomics data of the SARS-CoV-2 virus, in addition to epidemiological and geographical data. We examined how these mutations interact with each other, their co-occurrence and clustering. Our study offers for the first time a comprehensive description of all mutations with a focus on non-spike mutations and demonstrated that mutations in regions other than the Spike (S) genes are worth investigating further. Our research established that the Omicron variant has retained some mutations reported in other SARS-CoV-2 variants, yet many of its mutations are extremely rare in other variants and unique to Omicron. Some of these mutations have been linked to the transmissibility and immune escape of the virus, and indicate a significant shift in SARS-CoV-2 evolution. The most likely theories for the evolution of the Omicron variant were also discussed.

Despite the huge amount of accumulated data, the study of the main mechanisms of interaction between proteins and epigenetic mechanisms in health and various pathologies remains one of the most important problems of molecular biology. The search for various endogenous and exogenous factors affecting the epigenome of eukaryotes continues to be relevant. Lactoferrin is the second most abundant milk protein and has proven to be a very promising anti-inflammatory, antifungal, antibacterial, and anti-cancer agent. This protein can act as a transcription factor regulating the expression of some genes. However, little attention has been paid to the use of lactoferrin as an epigenetic modulating factor. This review demonstrates that lactoferrin can directly and/or indirectly influence epigenetic mechanisms (DNA methylation, histone modification, chromatin compaction, and microRNA pathways) in different types of cells, in particular cancer cells.

BACKGROUND: Neuroblastoma is one of the most common extracranial solid tumors in childhood. At present, epigenetic disorders play a significant role in neoplasms development. Since epigenetic changes in the cell are quite dynamic and reversible, epigenome-modulating exogenous agents can be used in epigenetic targeted therapy for various types of tumors. Therefore, the identification of these agents is still significant. Lactoferrin is one such potential molecule from the transferrin family. Currently, the anti-tumor properties of lactoferrin have been identified, but its effect on the epigenome of cells of various tumors types, particularly on neuroblastomas, is practically unknown. AIM: To study the effect of the exogenous recombinant human apolactoferrin on the viability and epigenomic status of IMR-32 neuroblastoma cells. MATERIALS AND METHODS: We studied human IMR-32 neuroblastoma cells after 72 hours of exposure to 8 doses of recombinant human apolactoferrin: 0.1, 0.5, 1, 5, 10, 50, 100 and 500 g/ml. The level of genome-wide DNA methylation and the degree of chromatin compaction in IMR-32 cells were quantified using commercial kits 5-mC DNA ELISA Kit, Global DNA Methylation LINE-1 Kit, as well as enzymatic hydrolysis of MspI / HpaII and DNaseI. RESULTS: The recombinant apolactoferrin reduces the viability of IMR-32 and, depending on the dose, differentially affects the level of genome-wide DNA methylation (СpG dinucleotides, CCGG sites, LINE-1 repeats) and the degree of chromatin compaction. At the same time, a complex picture of the epigenomic cellular response to the effect of apo-lactoferrin was observed (nonlinear nonmonotonic dose-effect relationship). CONCLUSIONS: We assumed that apolactoferrin modulates gene activity through epigenetic mechanisms, in particular, by changing the DNA methylation pattern and affecting the chromatin structure, which may be one of the molecular mechanisms of its anti-tumor effect.