Abstract P4-05-09: Matrin 3: A Novel Micro-Tubule Associated RNA Binding Protein That Acts As a Potent Tumor Suppressor

Abstract Microtubules are highly dynamic components of the cytoskeleton that play an important role in a wide range of cellular processes including cell division, cell motility and intracellular transport. Increasing evidence suggests that alterations in microtubule dynamics are critical for cancer growth and metastasis. Microtubule associated proteins (MAPs) regulate microtubule dynamics and consequently can affect sensitivity of cancer cells to microtubule targeting drugs. We discovered a novel microtubule associated protein "Matrin 3 (MATR3)" that is known to bind to RNA and play a critical role in RNA transport and RNA stabilization. Immunofluorescence analyses revealed that although MATR3 is predominantly a nuclear protein, it translocates to the cytoplasm and interacts with microtubules when breast cancer cells are treated with paclitaxel. We show that MATR3 associates with stabilized microtubules and it mediates microtubule polymerization in a taxol-dependent manner. Interestingly, our results reveal that MATR3 acts as a effective tumor suppressor as it inhibits breast cancer colony formation, migration and invasion of breast cancer cells in addition to suppressing breast tumor growth in vivo. Analysis of breast cancer samples showed a significantly lower expression of MATR3 when compared to normal adjacent tissues. Our results indicate the possibility that MATR3 mediates its tumor suppressor function by binding and regulating proteins that are known to affect microtubule dynamics. We believe that nuclear-cytoplasmic shuttling of MATR3 is critical for stability of key proteins that might regulate paclitaxel-dependent microtubule dynamics and subsequently cellular effects in cancer cells. Citation Format: Panneerdoss Subbarayalu, Subapriya Rajamanickam, Suryavathi Viswanadhapalli, Nicholas Dybdal-Hargreaves, Santosh Timilsina, Sanjay Bansal, Hima Bansal, Tabrez Mohammad, Yidong Chen, John C Herr, Susan L Mooberry, Manjeet K Rao. Matrin 3: A novel micro-tubule associated RNA binding protein that acts as a potent tumor suppressor [abstract]. In: Proceedings of the Thirty-Seventh Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2014 Dec 9-13; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2015;75(9 Suppl):Abstract nr P4-05-09.