Purpose: Osteoarthritis (OA) is the most common age related musculoskeletal disease leading to impairment in movement, with a total of 8.75 million people affected in UK only. During OA cartilage in joints start to deteriorate uncovering underlying bone, the friction of which causes pain. Accounting the studies up to date the mechanisms of cartilage degeneration are still not fully understood. Although, extracellular matrix composes 95% of the hyaline cartilage the only residing cells in the cartilage are chondrocytes. With regard to this, understanding biological processes regulating the homoeostasis of chondrocytes and defining the biomarkers of early OA attracts huge interest. Small nucleolar RNAs (snoRNAs) represent a class of regulatory RNAs, most of which involved in chemical modification of ribosomal RNAs and spliceosomal RNAs. One of the important snoRNA which associated with 18s rRNA maturation is U3, snoRNA binds to 18s pre-RNA in order to cleave 5’ ETS at A0 and A1 sites. Although, U3 possess conservative motives and their functions are similar among eukaryote species, the most of the work was carried out on Xenopus and Saccharomyces cerevisiae. In that context, it was interesting to investigate the role of snoRNAs in human cell lines. For that purpose we choose SW1353 cells, a human chondrosarcoma cell lineage which holds certain similarities with primary human chondrocytes. Methods: SW1353 cells were cultured in phenol red free Dulbecco's Modified Eagle medium supplemented with 10% Fetal bovine serum, 0.2% Amphotericin B, 1% Penicillin-Streptomycin and 1% L-Glutamin. Transfection of U3 antisense oligonucleotide and scrambled oligonucleotide (ASO) was carried out using HiPerfect transfection reagent. Total RNA from cells was extracted using TRIzol reagent and knockdown of U3 was confirmed by qPCR. Proteins of cell lysates and proteins secreted into media of U3 knockdown and scrambled cells were analysed on Q-exactive Orbitrap mass spectrometer. Proteins were identified using Mascot and quantified with ProgenesisQI™ software. Results: Amount of identified proteins derived from cell lysates were in the range of 951 and 473 proteins after adjustment to 1% FDR. Meanwhile, proteins from media showed far less proteins identified, with the highest 41 and the lowest 10 proteins in sample. The number of differently expressed (DE) proteins with at least 2-fold change and p< 0.05 was 124, of which 4 were downregulated in knockdown and 120 upregulated in cell lysate samples. However, media proteins showed difference in only few proteins (p<0.05), namely FLNB, EIF4B, SERPINE2, ALYREF and ECM1, all upregulated in knockdown samples. Among the top molecular and cellular functions in Ingenuity Pathway Analysis, DE proteins were accounted to cell death and survival, with 71 proteins mapped to the aforementioned cellular function. Conclusions: In current study we have showed the importance of U3 snoRNA in homeostasis of SW1353 cells, the knockdown of U3 leads to the upregulation of proteins involved in cell death pathway. Moreover, suppression of U3 expression increased activation in glycolysis pathway, we assume that is to compensate the reduction of mature and functional ribosomes.