STARD3, also known as StAR-related lipid transfer domain-3, is a sterol-binding protein. It is a member of the START family involved in lipid transfer, especially crucial for non-vesicular cholesterol transportation within the cell. It plays a role in creating endoplasmic reticulum (ER)-endosome contact sites and is involved in the cholesterol metabolic pathway, which is important as cancer cells have an increased demand for cholesterol [1,2,3,6].

In breast cancer, STARD3 is correlated with HER2 amplification as it is located on the same chromosome region. In a study of HER2-positive breast cancer patients, STARD3 protein expression was associated with pathological complete response after neoadjuvant systemic treatment, suggesting it could be a biomarker for predicting treatment response [4].

In diabetes-induced podocyte injury, upregulation of STARD3 leads to increased cholesterol transport from late endosomal/lysosomal to mitochondria, causing mitochondrial cholesterol accumulation and cell injury. Downregulating STARD3 expression alleviates this injury, indicating its potential as a therapeutic target for diabetic kidney disease [5].

In conclusion, STARD3 is essential for cholesterol transport within cells and plays a significant role in diseases such as breast cancer and diabetic kidney disease. Research on STARD3 using in vivo models helps in understanding its function in these disease conditions, providing potential new directions for biomarker discovery and therapeutic strategies.