A Priori Activation of Apoptosis Pathways of Tumor (AAAPT) technology: Development of targeted apoptosis initiators for cancer treatment

Abstract

Cancer cells develop tactics to circumvent the interventions by desensitizing themselves to interventions. Amongst many, the principle routes of desensitization include a) activation of survival pathways (e.g. NF-kB, PARP) and b) downregulation of cell death pathways (e.g. CD95/CD95L). As a result, it requires high therapeutic dose to achieve tumor regression which, in turn damages normal cells through the collateral effects. Methods are needed to sensitize the low and non-responsive resistant tumor cells including cancer stem cells (CSCs) in order to evoke a better response from the current treatments. Current treatments including chemotherapy can induce cell death only in bulk cancer cells sparing CSCs and cancer resistant cells (CRCs) which are shown to be responsible for high recurrence of disease and low patient survival. Here, we report several novel tumor targeted sensitizers derived from the natural Vitamin E analogue (AMP-001-003). The drug design is based on a novel concept “A priori activation of apoptosis pathways of tumor technology (AAAPT) which is designed to activate specific cell death pathways and inhibit survival pathways simultaneously and selectively in cancer cells sparing normal cells. Our results indicate that AMP-001-003 sensitize various types of cancer cells including MDA-MB-231 (triple negative breast cancer), PC3 (prostate cancer) and A543 (lung cancer) cells resulting in reducing the IC-50 of doxorubicin in vitro when used as a combination. At higher doses, AMP-001 acts as an anti-tumor agent on its own. The synergy between AMP-001 and doxorubicin could pave a new pathway to use AAAPT leading molecules as neoadjuvant to chemotherapy to achieve better efficacy and reduced off-target toxicity compared to the current treatments.

Rational Drug Design of Targeted and Enzyme-Cleavable Vitamin E Analogs as a Neoadjuvant to Chemotherapy: In Vitro and In Vivo Evaluation on Reduction of the Cardiotoxicity Side Effect of Doxorubicin

“…Extensive biological properties and potential biological targets of AMP derivatives without synthetic details have been recently published by Pandurangi et al , The new addition is AMP-004, which has dual cleavable linkers, one cleavable by Cathepsin B and another hydrazone that gets cleaved by low pH, which is considered to be the tumor environment. In general, we have reported IC50 values for AMPs in TNBC, gastric, and lung cancer cells, which are in the range of 10–30 μM and are similar to many FDA (Federal Drug Application)-approved drugs including doxorubicin. − AMP-004 is an exception because it has 10 times lower IC50 (0.22 μM) compared to standard chemotherapy doxorubicin (2.4 μM, Figure B) in MDA-MB-231 TNBC cells, perhaps due to the release of two drugs simultaneously.…”

“…GBM-BTSCs encompass heterogeneous populations of multipotent, self-renewing, and tumorigenic cells, which are proposed to be the root cause of therapeutic resistance and recurrence. We have shown in our earlier studies that AMPs target CSCs by inhibiting the NF-κB pathway . CSCs also overexpress Cathepsin B, which cleaves AMPs and, in the process, becomes a viable biological target for the AAAPT drug design.…”

“…Scheme 1 describes the selectivity of AMP drugs based on Cathepsin B positivity and low pH of the cancer environment. Regarding the specificity and cleavability of AMP drugs, we have earlier reported that cancer cells which are Cathepsin B-positive (e.g., MDA-MB-231 and MCF-7) did have significant uptake of AMP drugs proportional to Cathepsin B levels, while there was little or no uptake of AMP drugs in low Cathepsin B or negative normal cells (e.g., cardiomyocytes and normal breast epithelial cells MCF-10A; see Tables 1 and 2 in ref 43 The cleavability of AMP-002 and AMP-004 by human Cathepsin B was quantified by using HPLC (see the Supporting Information, Figures S15 and S18, respectively). Briefly, human Cathepsin B (0.2 mg/mL) in the presence of 0.04 mmol/L dithiothreitol and 10 mmol/L in (MES) buffer was mixed with AMP-002 solution slightly acidified by TFA to pH = 6.0.…”

“…Preliminary studies were concentrated on TNBC cells and cancer stem cells (CSCs). 43 In continuation with it, in this study, AMPs were studied in glioblastoma multiforme (GBM) brain tumor stem cells (BTSCs) and tumor cells derived from patients to expand the application of technology to other cancers. Cancer stem cells (CSCs) are believed to represent approximately 1% of the tumor as a distinct population and cause relapse and metastasis for greater than 40% of breast cancer patients.…”

“…We have shown in our earlier studies that AMPs target CSCs by inhibiting the NF-κB pathway. 43 CSCs also overexpress Cathepsin B, which cleaves AMPs and, in the process, becomes a viable biological target for the AAAPT drug design. For GBM, we selected brain tumor stem cells BT48, BT67, BT89, and BT189, which grow as neutrospheres (spheroid cell clusters).…”