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Mol Ther Oncolytics. 2019 Mar 20;14:57-65. doi: 10.1016/j.omto.2019.02.003. eCollection 2019 Sep 27.

Discretionary Transduction of MMP-Sensitized Tousled in Head and Neck Cancer.

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Department of Biochemistry and Molecular Biology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130, USA.
Feist-Weiller Cancer Center, Shreveport, LA, USA.


Oral radiotoxicity is often a limiting factor in cancer treatment. Previously, we demonstrated that transfer of cell-permeable, TAT-fusion Tousled-like kinase 1B (TLK1B) protein in salivary glands effectively mitigates radiation-induced salivary dysfunction. However, similar to most radioprotectors, TLK1B can carry the risk of limiting cancer treatment efficacy. The central goal of the study was, therefore, to reengineer TLK1B as a selective radioprotector of normal cells. Degradation of the extracellular matrix by proteases such as matrix metalloproteinases (MMPs) is a hallmark of aggressive tumors. Increased expression of membrane type 1-MMP (MT1-MMP; also called MMP14) is observed in a variety of cancers including head and neck squamous cell carcinoma (HNSCC). To limit TLK1B transduction to normal cells, we rendered the protein susceptible to MT1-MMP cleavage on the premise that high expression of MT1-MMP on the cell surface of HNSCC will suppress TLK1B internalization. Two optimal MT1-MMP-sensitive sequences (MS) were identified that when incorporated in TAT-TLK1B excluded its cellular entry in HNSCC, SCC40, but not immortalized salivary acinar cells, NS-SV-AC. Importantly, administration of MS-harboring TAT-TLK1B did not affect the sensitivity of tumors to radiation in a nude mouse xenograft tumor model. We conclude that a MMP-sensitive TLK1B can be an attractive therapeutic to allay salivary radiotoxicity without compromising cancer treatment efficacy.


DNA repair; HNSCC; MMP; TAT; TLK1; cell-permeable protein; radiation; radiation protection; salivary glands

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