Search Results (3)

Thyroid hormone L thyroxine stimulates pancreatic carcinoma cell proliferation via thyrointegrin αvβ3 receptors, and antagonist tetraiodothyroacetic acid (tetrac) inhibits cancer cell growth. Chemically modified bis-triazole-tetrac conjugated with polyethylene glycol (P-bi-TAT) has higher binding affinity to αvβ3 receptors compared to tetrac. We investigated the antiproliferation effect of P-bi-TAT in pancreatic cancer cells (SUIT2) and its radio- and chemo-sensitizing roles in a mouse model of pancreatic cancer. P-bi-TAT treatment increased tumor-targeted radiation-induced cell death and decreased tumor size. P-bi-TAT acted as a chemo-sensitizer and enhanced the 5-fluorouracil (5FU) effect in decreasing pancreatic tumor weight compared to 5FU monotherapy. Withdrawal of treatment continued the tumor regression; however, the 5FU group showed tumor regrowth. The mechanisms of the anti-cancer activity of P-bi-TAT on SUIT2 cells were assessed by microarray experiments, and genome-wide profiling identified significant alterations of 1348 genes’ expression. Both down-regulated and up-regulated transcripts suggest that a molecular interference at the signaling pathway-associated gene expression is the prevalent mode of P-bi-TAT anti-cancer activity. Our data indicate that non-cytotoxic P-bi-TAT is not only an anti-cancer agent but also a radio-sensitizer and chemo-sensitizer that acts on the extracellular domain of the cell surface αvβ3 receptor. Full article

(1) Background: Acute myeloid leukemia (AML) accounts for up to one-third of more than 60,000 leukemia cases diagnosed annually in the U.S. Primary AML cells express membrane αvβ3 integrin, which is associated with adverse prognosis and resistance to chemotherapies. A novel anticancer compound Polyethylene glycol-conjugated bi-TriAzole Tetraiodothyroacetic acid (P-bi-TAT) interacts with high affinity (Ki 0.3 nM) and specificity with the thyrointegrin αvβ3. We evaluated P-bi-TAT activities in two different AML models representing monocytic and myelocytic forms of acute leukemia. (2) Methods and Results: The in vivo AML models were established prior to initiation of treatment protocols by grafting human leukemia cells in immunocompromised mice. IVIS imaging scans revealed that leukemic colonies were extensively established throughout the bone marrow, liver, and lung of the untreated animals. In animals treated with P-bi-TAT at daily doses ranging from 1–10 mg/kg, subcutaneously for 2–3 weeks, IVIS imaging scans revealed 95% reduction in bone marrow colonies and leukemic colonies in liver and lung. Also, the leukemic cells were not detected in bone marrow samples of P-bi-TAT-treated animals. The anti-neoplastic effect of P-bi-TAT administration on leukemic cells was associated with marked inhibition of NF-κB activity. We conclude that experimental P-bi-TAT therapy in vivo appears extraordinarily effective against the two forms of human AML models in mice. Because the P-bi-TAT molecular target, thyrointegrin αvβ3, is consistently expressed in many, if not all, clinical AML samples, P-bi-TAT-based therapy seems to have significant clinical potential in treating most AML sub-types. Hence, P-bi-TAT represents a promising targeted therapeutic agent for AML patients. Full article

Integrin αvβ3 receptors are overexpressed in different tumors and their associated neovascularization and hence, represent a potential cancer target. We previously synthesized a high affinity thyrointegrin αvβ3, P₄₀₀₀-bi-TAT (tetrac derivative), with potent anticancer properties. However, the long polydisperse PEG conjugate showed large scaleup and analytical/bioanalytical issues. Hence, in the present study, we synthesized a mono versus bi-triazole tetrac with discrete monodisperse PEG, which provided improvement in scaleup and bioanalysis. In the present study, we compared binding affinity and anticancer activates with a smaller PEG size (P₁₆₀₀-bi-TAT, Compound 2) and the removal of one TAT molecule (P₁₆₀₀-m-TAT, Compound 3) versus P₄₀₀₀-bi-TAT, Compound 1. The results of the selectivity and affinity of TATs showed greater affinity to integrin αvβ3. The xenograft weights and tumor cell viabilities were decreased by >90% at all doses compared to the control (ON Treatment, *** p < 0.001) in cells treated with Compounds 1, 2, and 3 in U87-Luc-treated mice. The in vivo luminescent signals of U87-luc cells reflect the proliferation and distribution of tumor cells in the animals and the maximum intensity corresponding to the maximum tumor cells that the animals could tolerate. We found that the three thyrointegrin αvβ3 antagonists exhibited optimal therapeutic efficacy against U87 or primary glioblastoma cells. Biological studies showed that decreasing the PEG linker size (1600 vs. 4000) or having mono-TAT or bi-TAT had no significant impact on their αvβ3 binding affinity, anti-angiogenesis, or overall anti-cancer efficacy. Full article