Background: The present study aims to further explore the role of STK33 in hypopharyngeal squamous cell carcinoma (HSCC), with special attention given to the possible relationship between STK33 alteration and calcium.
Methods: An in vivo experiment and microarray analysis were performed to investigate the impact of STK33 knockdown (STK33-RNAi) on the biological behaviors and the gene profile alterations of a HSCC cell line (Fadu). Cell viability and morphological change of Fadu cells in response to Ionomycin were measured by MTT assay and acridine orange staining. The concentration of intracellular calcium ([Ca(2+)]i) was detected by laser scanning confocal microscope with fluo-3/AM. The mRNA and protein expressions of relevant genes were examined by real-time PCR and Western blot.
Results: STK33-RNAi retarded the Fadu cell proliferation and the metastasis in nude mice and led to up- and down-regulation of the expressions of abundance of genes, especially, the downregulation of the CAPN1 gene. Ionomycin increased the [Ca(2+)]i and decreased the survival rates of Fadu cells in a time-dependent manner. Moreover, Ionomycin resulted in the elevation of CAPN1 mRNA expression in normal Fadu cells and, conversely, had almost no effect on CAPN1 expression in STK33-RNAi cells.
Conclusions: Findings from this work further validate that STK33 is a potential oncogene and plays an important role in tumorigenesis of HSCC via regulation of numerous genes. In addition, there exists the reciprocal influence between STK33 and [Ca(2+)]i in Fadu cells.
Keywords: Calcium; STK33; calpain; fadu cells; ionomycin.