L1TD1, also known as FLJ10884 or ECAT11, is a cytoplasmic RNA-binding protein. It is specifically expressed in pluripotent stem cells and is essential for maintaining stemness in human cells. L1TD1 is the only known protein-coding gene domesticated from a LINE-1 (L1) retroelement. It plays roles in RNA splicing, translation, protein traffic, and degradation, and is part of the pluripotency interactome network of OCT4, SOX2, and NANOG, bridging nuclear and cytoplasmic regulation [2,3].

In medulloblastoma, high L1TD1 expression is correlated with poor prognosis. Depletion of L1TD1 protein levels by targeted gene silencing significantly reduces medulloblastoma cell viability, inhibits cell proliferation, induces apoptosis, downregulates neural stem cell markers (CD133 and Nestin), inhibits neurosphere generation, and sensitizes cells to chemotherapeutic agents [5]. In contrast, in colon cancer, increased L1TD1 expression is a positive prognostic marker associated with longer disease-free survival, and it shows a lack of co-expression with its interaction partners compared to medulloblastoma [1]. In non-small cell lung cancers (NSCLC), L1TD1 is tumor-specifically methylated, and its DNA methylation is involved in transcriptional regulation. Overexpression of L1TD1 in NSCLC cells reduces cell growth, proliferation, and viability both in vitro and in vivo [4].

In conclusion, L1TD1 has diverse functions in maintaining pluripotency and is involved in multiple disease conditions. The study of L1TD1 in disease models such as medulloblastoma, colon cancer, and NSCLC reveals its complex role in tumorigenesis, prognosis, and response to treatment, highlighting its potential as a prognostic marker and therapeutic target.