Tissue microarray staining reveals PLD1 and Sp1 have a collaborative, pro-tumoral effect in patients with osteosarcomas

It has been reported that phospholipase D1 (PLD1) - a key enzyme involved in lipid metabolism - is important for the initiation and progression of various human solid cancers; however, its biological significance and regulation in human osteosarcomas remain elusive. In this study, We found that PLD1 and Specificity Protein 1 (Sp1) expression were elevated in 137 osteosarcoma specimens with immunohistochemical staining. Our results showed that both PLD1 and Sp1 were expressed at much higher rates in the cancerous tissue compared to adjacent normal tissue. A correlation analyze also indicated that PLD1 was significantly associated with lactate dehydrogenase expression (p = 0.041) and the Enneking stage (p = 0.000), while Sp1 was significantly associated with the nuclear grade (p = 0.024). Furthermore, survival analyses showed that elevated PLD1 confers a poor prognosis on patients with osteosarcomas, acting as an independent prognostic factor. Of note, we showed a positive correlation between PLD1 and Sp1 expression in the cancer tissues (r = 0.357; p < 0.001). High co-expression of the two molecules results in the worst prognosis for the patients, and can also be regarded as independent prognostic factor (p = 0.001; HR = 2.71; 95% CI 1.53–4.80).