Purpose: Intratumoral hypoxia is a major regulator of radio-resistance in the cancer treatment due to reduced blood supply by the immature blood vessels and necrotic tumor core. An African indigenous Justicia plant (family Acanthanceae), has been shown to be evolutionized to contain hemoglobin which shows similarity with human α and β Hemoglobin whereas, plant usually have rudimentary hemoglobin called hemoglobin ɣ. Here, we used this plant hemoglobin extract to increase the radiosensitivity of the cancer treatment during radiotherapy.
Methods: Lyophilized Justicia plant extract was analyzed for its hemoglobin content. ELISA was performed using Human Hemoglobin Kit (Sigma-Aldrich) to quantify the Hemoglobin concentration (human type). Western blot assay was performed to confirm α and β hemoglobin chains using Human Hemoglobin α and β antibody (abcam, 1:150 ratio), and a study as remedy for anemia common in cancer patients undergoing radiotherapy was performed in a mouse model. To evaluate the radio-sensitizing effect in cancer treatment, Panc-02 tumors were generated in C57BL/6 mice and treated with Plant hemoglobin (0.1mg/Kg) intratumorally just before radiation treatment (10 Gy) using the small animal radiation research platform (SARRP). Tumor measurement and survival analysis were performed.
Results: Well characterized plant hemoglobin was injected intratumoraly prior to radiation treatment in pancreatic adenocarcinoma mouse model comparing with a cohort only with same dose of radiation treatment. Control group was treated only with PBS. Significant reduction of tumor volume was observed in the plant Hemoglobin+Radiation treated group compare to the cohort with only radiation treatment (p<0.0001). Significant longer survival duration was also observed in this combination treated group (p<0.0001) confirming significant radio-enhancer effect of this plant hemoglobin for cancer treatment.
Conclusion: The Plant hemoglobin can be developed as a radio-enhancer in solid tumor radiation treatment.