Abstract
Hypopharyngeal cancer is a distinct type of malignant head and neck tumor, which exhibits low sensitivity to anti-cancer drugs. The importance of developing methods for reducing chemotherapy resistance, and improving and enhancing prognosis has previously been emphasized and is considered a challenge for effective clinical treatment of hypopharyngeal cancer. The current study investigated the effects of co‑expression of inhibitor of growth protein 4 (ING4) and P53, a tumor suppressor gene, on chemosensitivity to cisplatin in human hypopharyngeal cancer xenografts in vivo, and the potential molecular mechanisms involved. A tumor model was established by injecting athymic nude mice with FADU human hypopharyngeal cancer cells. Five days after intratumoral and peritumoral injections of an empty adenoviral vector (Ad), Ad‑ING4‑P53, cisplatin, or a combination of Ad‑ING4‑P53 and cisplatin (Ad‑ING4‑P53 + cisplatin) every other day for 5 days, the mice were euthanized and their tumors, livers, and kidneys were removed. The tumor weights were used to calculate the inhibition rate, and the expression levels of ING4 and P53 were detected by reverse transcription‑polymerase chain reaction. Additionally, apoptotic cells were detected using terminal deoxynucleotidyl transferase dUTP nick end labeling, and immunohistochemistry determined the levels ING4, P53, B‑cell lymphoma‑2 (Bcl‑2) and Bcl‑2 associated X protein (Bax) protein expression. The results demonstrated increased expression of ING4 and P53 in the Ad‑ING4‑P53 groups compared with PBS and Ad groups, indicating successful introduction of the genes into the tumor cells. Notably, the Ad‑ING4‑P53 + cisplatin group exhibited a higher inhibition rate compared with the four other groups. The results of immunohistochemistry analysis demonstrated that Bax expression was increased and Bcl‑2 was decreased in the Ad‑ING4‑P53 + cisplatin group. This suggested that the enhanced cisplatin chemosensitivity with Ad-ING4-P53 gene therapy in hypopharyngeal cancer xenografts may be associated with apoptosis induction through upregulation of Bax expression and downregulation of Bcl‑2. The results of the present study indicated that gene therapy combined with cisplatin treatment may be a promising treatment for human hypopharyngeal cancer.