We seek to use a novel cell-internalization SELEX (Systemic Evolution of Ligands by Exponential enrichment) to isolate thioaptamer-conjugated liposomal nanoparticles (TA-NP) that internalize and deliver its siRNA into the cytosol of tumor initiating cells (TIC) of oral squamous cell carcinoma, minimizing off-target delivery. In vivo delivery and release of siRNA from the endosomes to cytosol remain the two biggest obstacles for translating anticancer siRNA drugs to the clinic. Oral squamous cell carcinoma commonly known as oral cancer (OC) is the most common malignancy of head and neck with high global public health impact. Fanconi anemia (FA) is a hereditary cancer syndrome that predisposes one to OC. Evidence points to TIC as the key driver of field cancerization, resistance to therapy and disease relapse. A therapeutic vehicle that selectively targets and delivers anticancer drugs to TIC offers great promise for OC treatment. Our data and published studies show: (1).TIC is more enriched in FA-OC than sporadic OC;(2) Chk1 and CD147 promote TIC survival and chemoresistance and its overexpression contribute to poor prognosis in OC. The main goal of this proposal is to use FA- OC-TIC as target cells to develop TA- NP for the cytosolic delivery of siRNA. We hypothesize that isolated TA-NP will facilitate targeted delivery of siRNA to OC-TIC cytosol, and silence CD-147/Chk1 in OC-TIC's, disrupting their niche and rendering them chemosensitive and susceptible to elimination by chemotherapy with gemcitabine.
Aims :(1): Elucidate the effect of RNAi mediated silencing of CD147/Chk1 in FA-OC-TIC; (2A): Select a list of TA-Liposomal NP (TA-NP) specific for TIC fraction of FA-OC cells, while avoiding hepatocyte uptake, using a positive and negative cell-uptake based SELEX;(2B): Determine the selected TA-NP's targeting specificity and therapeutic efficacy in in vitro and in murine OC xenografts. We will isolate ALDH+ TIC in FA-OC cell lines and examine the effects of siRNA-mediated silencing of CD147 and Chk1. (2) We will use a modified conjugate SELEX with positive and negative selections to identify OC-TIC-specific internalizing TA-NP. (3) We will validate TIC-targeting specificity and silencing efficacy of isolated TA-NP-sRNA in vitro and in murine orthotopic FA-OC xenografts. RNAi mediated inhibition of CD147 and Chk1 in OC-TIC will yield valuable insight into their potential role in the tumor propagating and chemoresistant properties of OC-TIC. The proposed TA-NP will have important clinical potentials for in vivo delivery of therapeutic and imaging agents targeting the OC-TIC.

Public Health Relevance

Oral cancer is the most common malignancy of the head and neck region and is associated with a poor prognosis due frequent local and distant tumor relapse after treatment. Tumor relapse is caused by the persistence of cancer stem cells also known as tumor initiating cells. These tumor initiating cells are inherently chemoradiation therapy resistant and hence are not eliminated with the current treatments. Our project is aimed at developing a therapeutic modality that can selectively target the tumor initiating cells and deliver siRNA drugs to overcome their therapeutic resistance in order to improve disease free survival and cure rate in patients with oral cancer.

National Institute of Health (NIH)
Research Project (R01)
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Special Emphasis Panel (ZDE1)
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Venkatachalam, Sundaresan
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University of Texas Health Science Center Houston
Other Basic Sciences
Schools of Dentistry/Oral Hygn
United States
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Gandham, Sai Hari A; Volk, David E; Lokesh, Ganesh L R et al. (2014) Thioaptamers targeting dengue virus type-2 envelope protein domain III. Biochem Biophys Res Commun 453:309-15