Enhancing tumor cell response to chemotherapy through nanoparticle-mediated codelivery of siRNA and cisplatin prodrug

Abstract

Cisplatin and other DNA-damaging chemotherapeutics are widely used to treat a broad spectrum of malignancies. However, their application is limited by both intrinsic and acquired chemoresistance. Most mutations that result from DNA damage are the consequence of error-prone translesion DNA synthesis, which could be responsible for the acquired resistance against DNAdamaging agents. Recent studies have shown that the suppression of crucial gene products (e.g., REV1, REV3L) involved in the errorprone translesion DNA synthesis pathway can sensitize intrinsically resistant tumors to chemotherapy and reduce the frequency of acquired drug resistance of relapsed tumors. In this context, combining conventional DNA-damaging chemotherapy with siRNAbased therapeutics represents a promising strategy for treating patients with malignancies. To this end, we developed a versatile nanoparticle (NP) platform to deliver a cisplatin prodrug and REV1/ REV3L-specific siRNAs simultaneously to the same tumor cells. NPs are formulated through self-assembly of a biodegradable poly(lactide-coglycolide)-b-poly(ethylene glycol) diblock copolymer and a self-synthesized cationic lipid. We demonstrated the potency of the siRNA-containing NPs to knock down target genes efficiently both in vitro and in vivo. The therapeutic efficacy of NPs containing both cisplatin prodrug and REV1/REV3L-specific siRNAs was further investigated in vitro and in vivo. Quantitative realtime PCR results showed that the NPs exhibited a significant and sustained suppression of both genes in tumors for up to 3 d after a single dose. Administering these NPs revealed a synergistic effect on tumor inhibition in a human Lymph Node Carcinoma of the Prostate xenograft mouse model that was strikingly more effective than platinum monotherapy.siRNA delivery | chemosensitivity | combination therapy A dvances in genomics and cell biology have highlighted the heterogeneity and complexity of cancer. It is generally accepted that cancer is usually the result of a combination of interconnected disease pathways that may not be treated effectively with 1D therapeutic mechanisms (1). The inhibition of a pathway by a single-drug therapy often results in the emergence of drug resistance and tumor relapse, largely because of pathway redundancy, cross-talk, compensatory and neutralizing actions, and antitarget activities that commonly occur with single-drug cancer therapy (2). In some cases, relapse can result in the emergence of phenotypically distinct and possibly more virulent tumors. For example, treatment of prostatic adenocarcinoma with androgen ablation therapies, such as abiraterone or enzalutamide, results in the development of abiraterone or enzalutamide refractory castration-resistant prostate cancer that is phenotypically nonadenocarcinoma and represents a rare and often lethal form of prostate cancer with a neuroendocrine phenotype (3).Platinum agents are among the most widely used cytotoxic agents for cancer therapy. Cisplatin and other DNA adductforming chemotherapeutics caus...

Breakthrough for a DNA break-preventer

“…This tumor formation is consistent with the chromosomal instability that accompanies the Pol ζ defect (9,10). At the same time, Pol ζ is a potentially important target in cancer therapy, because in mouse xenograft models suppression of REV3L function can sensitize intrinsically resistant tumors to chemotherapy and reduce the frequency of acquired drug resistance of relapsed tumors (11).…”

Long-circulating siRNA nanoparticles for validating Prohibitin1-targeted non-small cell lung cancer treatment

“…The new generation lipid-polymer hybrid NP platform developed herein has several unique features. In contrast to previously reported hybrid polymer NPs loaded with cationic lipid/polyamine-siRNA complexes (14)(15)(16)(17)(18)32), which are formulated by emulsion techniques and are relatively large, our robust self-assembly strategy leads to the synthesis of hybrid NPs with relatively small size (≤100 nm) and long circulation time (t 1/2 ∼8 h). Smaller NPs are considered to be more efficient in crossing leaky microvasculature and show higher tumor accumulation than larger NPs (33,34).…”

“…1B), with siRNA encapsulation efficiency at ∼80% and a loading of ∼640 pmol siRNA/mg PLGA. Compared with traditional lipidpolymer hybrid RNAi NPs that were prepared by the double emulsion/solvent evaporation methods (14)(15)(16)(17)(18), this self-assembled hybrid NP is much smaller and more uniform, and can be easily made, while retaining comparable siRNA encapsulation efficiency. In addition, the solid PLGA polymer core offers a more rigid and stable nanostructure that can better protect the encapsulated siRNA than the lipid-siRNA complex (lipoplex) structure (SI Appendix, Fig.…”

“…Our results verify that the RNAi hybrid NP system offers a means for rapid in vivo validation of potential cancer targets, particularly those considered undruggable. As the hybrid NPs can also simultaneously carry small molecular drugs (e.g., cisplatin prodrug) in the PLGA polymer core (15,36), the co-delivery of siRNA/drug combinations may present a therapeutic advantage in cancer treatment (37,38). In summary, we have rationally developed a distinctive lipid-polymer hybrid NP platform for effective systemic siRNA delivery, through a simple and robust self-assembly strategy, and expect that it provides a useful toolkit for both fundamental cancer research and clinical development of novel RNAi therapeutics.…”

REV1 promotes PCNA monoubiquitylation through interacting with ubiquitylated RAD18

“…The multiple regulatory roles of REV1 in the error-prone TLS pathway make it a promising target for chemotherapy. In support of this, recent studies using mouse lymphoma and prostate cancer models have shown that depletion of REV1 can remarkably inhibit drug-induced mutagenesis and sensitize cancer cells to chemotherapy (Xie et al, 2010;Xu et al, 2013).…”