Total RNA was isolated using TRIzol-chloroform extraction, followed by isopropanol precipitation. To remove DNA, RNA was treated with TURBO DNA-free™ Kit (Ambion, Cat.#AM1907). The samples were submitted to the Centre for PanorOmic Sciences (CPOS, HKU LKS Faculty of Medicine) for library preparation with KAPA Hyper Prep Kit following manufacturer protocol.