Tmem121, also known as transmembrane protein 121, has been implicated in multiple biological processes. It may be involved in glycosylation as a genome-wide association study identified it as one of the loci associated with both IgA and IgG glycomes, suggesting its role in immune-related glycosylation processes [1]. Additionally, it has potential functions in cell growth and metastasis-related pathways [2].

A study on cervical cancer cells showed that Tmem121 is significantly downregulated in cervical squamous cell carcinoma and endocervical adenocarcinoma compared to paracancerous tissues, with increased promoter methylation in tumor tissues. Gain-of-function and loss-of-function experiments in HeLa cells demonstrated that overexpression of Tmem121 reduced cell viability, inhibited cell migration, and regulated the expression of multiple cancer-related molecules such as BCL-2, cyclin D1, and p-AKT. Conversely, knockdown of Tmem121 promoted the expression of certain proteins like cyclin E1 [2]. In prostate cancer, the cardiac glycoside deslanoside downregulated Tmem121, and survival analyses in the TCGA database showed that downregulated Tmem121 inversely correlated with disease-free survival, indicating its potential role in prostate cancer progression [3].

In conclusion, Tmem121 appears to have important functions in cancer-related processes, especially in cervical and prostate cancer. The downregulation of Tmem121 in cancer tissues and its effects on cell viability, migration, and cancer-associated signaling pathways, as demonstrated through in vitro gain-and loss-of-function experiments, suggest its potential as a novel target for cancer diagnosis and therapy. Its role in glycosylation also indicates its broader significance in immune-related biological functions.

References:

1. Visconti, Alessia, Rossi, Niccolò, Bondt, Albert, Suhre, Karsten, Falchi, Mario. 2024. The genetics and epidemiology of N- and O-immunoglobulin A glycomics. In Genome medicine, 16, 96. doi:10.1186/s13073-024-01369-6. https://pubmed.ncbi.nlm.nih.gov/39123268/

2. Yang, Boyu, Cai, Yi, Zhu, Ping, Li, Yongqing, Fan, Xiongwei. 2022. Transmembrane protein 121 as a novel inhibitor of cervical cancer metastasis. In Experimental and therapeutic medicine, 24, 572. doi:10.3892/etm.2022.11509. https://pubmed.ncbi.nlm.nih.gov/35978921/

3. Liu, Mingcheng, Huang, Qingqing, A, Jun, Zhang, Zhiqian, Dong, Jin-Tang. 2021. The Cardiac Glycoside Deslanoside Exerts Anticancer Activity in Prostate Cancer Cells by Modulating Multiple Signaling Pathways. In Cancers, 13, . doi:10.3390/cancers13225809. https://pubmed.ncbi.nlm.nih.gov/34830961/

4. Sharapov, Sodbo Zh, Tsepilov, Yakov A, Klaric, Lucija, Lauc, Gordan, Aulchenko, Yurii S. . Defining the genetic control of human blood plasma N-glycome using genome-wide association study. In Human molecular genetics, 28, 2062-2077. doi:10.1093/hmg/ddz054. https://pubmed.ncbi.nlm.nih.gov/31163085/