Comparison of the synergistic anticancer activity of AlPcS4 photodynamic therapy in combination with different low‑dose chemotherapeutic agents on gastric cancer cells

: Limited cellular delivery and internalization efficiency of Al(III) phthalocyanine chloride tetrasulfonic acid (AlPcS4) induce poor penetration ability in cells and a slight photodynamic therapy (PDT) effect on gastric cancer. The combination treatment of AlPcS4/PDT with low‑dose chemotherapeutic agents may provide a promising treatment strategy to increase the weak delivery efficiency of AlPcS4, reducing the dose of chemical agents without reducing efficacy, and improving apoptosis‑inducing abilities, thereby increasing the antitumor effects and decreasing the noxious side effects on gastric cancer. We investigated and compared the synergistic antitumor growth effect on gastric cancer cells by combining AlPcS4/PDT treatment with different low‑dose chemotherapeutic agents, namely, 5‑fluorouracil (5‑FU), doxorubicin (DOX), cisplatin (CDDP), mitomycin C (MMC), and vincristine (VCR). The inhibitory effect was increased in treatments that combined AlPcS4/PDT with all the aforementioned low‑dose chemotherapeutic agents, to a different extent. An evident synergistic effect was obtained in the combination treatment of AlPcS4/PDT with low‑dose 5‑FU, DOX, and MMC by increasing AlPcS4 intracellular uptake ability, improving apoptosis‑inducing abilities, and prolonging apoptosis‑inducing time. The low‑dose chemotherapeutic agents prolonged the apoptosis‑inducing period of AlPcS4/PDT, and AlPcS4/PDT quickly improved apoptosis‑inducing abilities of chemotherapy even at low doses. Generally, the combination treatment of AlPcS4/PDT with low‑dose chemotherapeutic agents had significant antitumor growth effects in addition to a low dark‑cytotoxicity effect on gastric cancer, thereby representing an effective and feasible therapy method for gastric cancer.