Abstract: Objective To analyze the expression of hydroxysteroid dehydrogenase like 2 (HSDL2) in rectal cancer tissues and the effect of changes in HSDL2 expression level on proliferation of rectal cancer cells. Methods Clinical data and tissue samples of 90 patients with rectal cancer admitted to our hospital from January 2020 to June 2022 were collected from the prospective clinical database and biological specimen database. The expression level of HSDL2 in rectal cancer and adjacent tissues was detected by immunohistochemistry, and based on the median level of HSDL2 expression, the patients were divided into high expression group (n=45) and low expression group (n=45) for analysis the correlation between HSDL2 expression level and the clinicopathological parameters. GO and KEGG enrichment analyses were performed to explore the role of HSDL2 in rectal cancer progression. The effects of changes in HSDL2 expression levels on rectal cancer cell proliferation, cell cycle and protein expressions were investigated in SW480 cells with lentivirus-mediated HSDL2 silencing or HSDL2 overexpression using CCK-8 assay, flow cytometry and Western blotting. Results The expressions of HSDL2 and Ki67 were significantly higher in rectal cancer tissues than in the adjacent tissues (P<0.05). Spearman correlation analysis showed that the expression of HSDL2 protein was positively correlated with Ki67, CEA and CA19-9 expressions (P<0.01). The rectal cancer patients with high HSDL2 expressions had significantly higher likelihood of having CEA ≥5 μg/L, CA19-9 ≥37 kU/L, T3-4 stage, and N2-3 stage than those with a low HSDL2 expression (P<0.05). GO and KEGG analysis showed that HSDL2 was mainly enriched in DNA replication and cell cycle. In SW480 cells, HSDL2 overexpression significantly promoted cell proliferation, increased cell percentage in S phase, and enhanced the expression levels of CDK6 and cyclinD1 (P<0.05), and HSDL2 silencing produced the opposite effects (P<0.05). Conclusion The high expression of HSDL2 in rectal cancer participates in malignant progression of the tumor by promoting the proliferation and cell cycle progress of the cancer cells.

Key words: rectal cancer; HSDL2; cell proliferation; cell cycle; biomarkers