Acquired Drug Resistance Enhances Imidazoquinoline Efflux by P-Glycoprotein

Efflux-Enhanced Imidazoquinolines To Exploit Chemoresistance

The imidazoquinoline family of toll-like receptor (TLR) immune cell agonists has long demonstrated moderate anticancer immunogenic effects by activating tumoricidal immune cells and depleting immunosuppressive cells within the tumor microenvironment. At a molecular level, we have also established that several imidazoquinolines traffic from within cancer cells to the extracellular space via P-glycoprotein (P-gp)-mediated efflux, a process commonly upregulated as multidrug-resistant (MDR) cancers acquire chemoresistance. However, imidazoquinoline P-gp efflux has never been deliberately enhanced to exploit this process. This study pioneers efforts to optimize imidazoquinoline efflux, ultimately balancing immunogenic potency alongside functional efflux susceptibility. Starting from an established imidazoquinoline scaffold previously optimized for potency, efflux was significantly enhanced by elaborating the N1 benzylic position with amide- and sulfonamide-linked P-gp affinity fragments consisting of empirically established P-gp substrates as well as computationally predicted P-gp binders. Lead compounds were identified from this series that exhibited enhanced P-gp efflux with functional retention of TLR agonism. Similar to the parent imidazoquinoline scaffold, leads had limited direct cytotoxicity in both treatment-naive and MDR B16 melanoma models and did not significantly affect the efficacy or trafficking of the chemotherapeutic doxorubicin. Efflux-enhanced imidazoquinolines were preferentially expelled from MDR-B16 cells relative to treatment-naive cells, resulting in immunogenicity that was enhanced as a consequence of the acquired MDR phenotype. Because enhanced P-gp-mediated efflux is common to most MDR cancer types, we envision that these results could inspire the design of immunotherapeutic drugs with mechanisms of action that are broadly enhanced in MDR cancers that have failed treatment or acquired resistance to chemotherapeutics.

Curcumin in treatment of hematological cancers: Promises and challenges

Hematological cancers include leukemia, myeloma and lymphoma and up to 178.000 new cases are diagnosed with these tumors each year. Different kinds of treatment including radiotherapy, chemotherapy, immunotherapy and stem cell transplantation have been employed in the therapy of hematological cancers. However, they are still causing death among patients. On the other hand, curcumin as an anti-cancer agent for the suppression of human cancers has been introduced. The treatment of hematological cancers using curcumin has been followed. Curcumin diminishes viability and survival rate of leukemia, myeloma and lymphoma cells. Curcumin stimulates apoptosis and G2/M arrest to impair progression of tumor. Curcumin decreases levels of matrix metalloproteinases in suppressing cancer metastasis. A number of downstream targets including VEGF, Akt and STAT3 undergo suppression by curcumin in suppressing progression of hematological cancers. Curcumin stimulates DNA damage and reduces resistance of cancer cells to irradiation. Furthermore, curcumin causes drug sensitivity of hematological tumors, especially myeloma. For targeted delivery of curcumin and improving its pharmacokinetic and anti-cancer features, nanostructures containing curcumin and other anti-cancer agents have been developed.

Multimodal Nanoplatform with ROS Amplification to Overcome Multidrug Resistance in Prostate Cancer via Targeting P-Glycoprotein and Ferroptosis

Chemotherapy remains the most essential treatment for prostate cancer, but multidrug resistance (MDR) contributes to chemotherapy failure and tumor-related deaths. The overexpression of P-glycoprotein (P-gp) is one of the main mechanisms behind MDR. Here, this work reports a multimodal nanoplatform with a reactive oxygen species (ROS) cascade for gas therapy/ferroptosis/chemotherapy in reversing MDR. The nanoplatform disassembles when responding to intracellular ROS and exerts three main functions: First, nitric oxide (NO) targeted delivery can reverse MDR by downregulating P-gp expression and inhibiting mitochondrial function. Second, ferrocene-induced ferroptosis breaks the redox balance in the tumor intracellular microenvironment and synergistically acts against the tumor. Third, the release of paclitaxel (PTX) is precisely controlled in situ in the tumor for chemotherapy that avoids damage to normal tissues. Excitingly, this multimodal nanoplatform is a promising weapon for reversing MDR and may provide a pioneering paradigm for synergetic cancer therapy.