The aim of this study was to explore the synergistic anti-
tumor effects of
cytarabine hyaluronic acid-
tyramine (
Ara-HA-Tyr)
hydrogel conjugates and
radiotherapy (RT) in the Lewis
lung cancer (LLC) xenograft model, and the mechanisms involved. The
radiotherapy sensitization ratio (SER) of 0.5 μg
cytarabine (
Ara-C) was 1.619 in the LLC cells.
Ara-HA-Tyr was prepared by encapsulating
Ara-C into
hyaluronic acid-
tyramine (HA-Tyr) conjugates. The
hydrogels were formed through the oxidative coupling of tyramines by
hydrogen peroxide (H2O2) and
horseradish peroxidase (HRP). Mice engrafted with the LLC cells were given intra-tumoral
injections of saline,
Ara-C or
Ara-HA-Tyr, with or without RT. The combination of
Ara-HA-Tyr and RT increased survival compared to free
Ara-C and RT (p < 0.05), and prolonged
tumor growth delay (TGD). Furthermore, the RT + Ara-HA-Tyr combination
therapy significantly reduced
18F-FDG uptake, induced cell cycle arrest at G2/M-phase, increased apoptosis and
histone H2AX phosphorylation (γ-H2AX), and decreased the proliferation index (Ki67) in
tumor cells compared to either monotherapy. Taken together,
Ara-C encapsulated with HA-Tyr effectively sensitized
tumor xenografts to RT and showed significantly less systemic toxicity. Graphical abstract In this work,
Ara-C encapsulated with
hyaluronic acid-
tyramine conjugates (HA-Tyr) was prepared and used to investigate its synergistic anti-
tumor efficacy by combination with
radiotherapy in the Lewis
lung cancer xenograft model. The synergistic mechanism may be related to
tumor cell cycle redistribution, apoptosis and expression of
histone H2AX phosphorylation.