Cellular Redox Status Regulates Emodin-Induced Radiosensitization of Nasopharyngeal Carcinoma Cells In Vitro and In Vivo

Pharmacokinetic characteristics of emodin in polygoni Multiflori Radix Praeparata

ETHNOPHARMACOLOGICAL RELEVANCE

Polygoni Multiflori Radix Praeparata (Zhiheshouwu) has been a Wudang Taoist medicine for tonifying the liver and kidney, resolving turbidity and reducing lipid. Emodin is one of the active anthraquinones in Zhiheshouwu. Our previous studies showed that emodin (EM) and the other anthraquinones in Zhiheshouwu extract (HSWE) exerted similar inhibitory effects on liver cancer cells in vitro. However, it is still unknown if the other anthraquinones enhance pharmacokinetics (PK) of EM in HSWE in vivo.

AIM OF THE STUDY

In this study, we compared the PK characteristics of EM alone with that in Zhiheshouwu aiming to explore which anthraquinones in HSWE contribute to the changed PK of EM in rats.

MATERIALS AND METHODS

Quality control of HSWE was determined using high performance liquid chromatography (HPLC). The ratios of emodin to other anthraquinones, physcion (PH), chrysophanol (CH), rhein (RH), aloe-emodin (AE), emodin-8-O-β-D-glycoside (EMG), physcion-1-O-β-D-glycoside (PHG) and chrysophanol-8-O-β-D-glycoside (CHG) in HSWE were determined and analyzed using UPLC combined with tandem mass spectrometry (UPLC/MS). The PK parameters and intestinal tissue concentration of EM alone, EM in HSWE, or with other anthraquinones in SD rats were analyzed using UPLC/MS.

RESULTS

The quality of the Zhiheshouwu samples met the quality standard of the Chinese Pharmacopoeia (Version 2020). The PK results showed that compared with EM alone, C_max (239.90 ± 146.71 vs. 898.46 ± 291.62, P < 0.001), T_max (0.26 ± 0.15 vs. 12.55 ± 1.33, P < 0.001), AUC_0-t (1575.09 ± 570.46 vs. 12154.96 ± 5394.25, P < 0.001), and AUC_0-∞ (4742.51 ± 1837.62 vs. 37131.34 ± 21647.39, P < 0.001) of EM in HSWE were decreased due to PH and EMG, while the values of V_d (380.75 ± 217.74 vs. 11.75 ± 7.35, P < 0.001), T_1/2 (10.81 ± 1.99 vs. 6.65 ± 2.76, P < 0.05) and CL (19.30 ± 7.82 vs. 2.78 ± 1.88, P < 0.001) of EM in HSWE were increased due to PH and AE. In addition, the intestinal tissue concentration of emodin in HSWE was decreased compared with that of EM alone in 20 and 780 min (25.37 ± 5.98 vs. 43.29 ± 4.16 and 26.72 ± 4.03 vs. 43.40 ± 14.19, respectively. P < 0.05) dominantly due to RH and PH.

CONCLUSION

In conclusion, compared with treatment of EM alone, the AUC_0-t value of EM in HSWE was decreased with different ways in rats. PH shortened T_max, and increased V_d and CL. While AE prolonged T_1/2 of EM. This indicated that the other anthraquinones in HSWE changed the PK of EM in rats and participated in the complex effects of EM on liver cancer. Besides the other anthraquinones, other components (e.g., 2,3,5,4'-tetrahydroxystilbene-2-O-β-D-glucoside) in Zhiheshouwu may contribute in the pharmacokinetic and pharmacodynamic interactions with EM for anti-liver cancer.

Pharmacokinetics, Tissue Distribution, and Excretion Characteristics of a Radix Polygoni Multiflori Extract in Rats

Although progress has been achieved in the pharmacological activity and toxicity of Radix Polygoni Multiflori (RPM), the chemical basis of its toxicity is still unclear. Here, we performed a multicompound pharmacokinetic analysis and investigated the tissue distribution and excretion characteristics of RPM components after oral administration in rats. The findings demonstrated that the active ingredients of the RPM extract were quickly absorbed after oral administration, with high exposure levels of emodin, 2,3,5,4′-teterahydroxystilbene-2-O-β-D-glucoside (TSG), citreorosein, torachrysone-8-O-glucoside (TG), emodin-8-O-β-D-glucoside (EG), and physcion-8-O-β-D-glucoside (PG). The tissue distributions of emodin, TSG, TG, EG, and PG were high in the liver and kidney. These components were the key contributors to the effectiveness and toxicity of RPM on the liver and kidney. Most of the active ingredients were mainly excreted through feces and bile, while a few were converted into other products in the body and excreted through urine and feces.

Phytochemicals as Potential Chemopreventive and Chemotherapeutic Agents for Emerging Human Papillomavirus-Driven Head and Neck Cancer: Current Evidence and Future Prospects

Head and neck cancer (HNC) usually arises from squamous cells of the upper aerodigestive tract that line the mucosal surface in the head and neck region. In India, HNC is common in males, and it is the sixth most common cancer globally. Conventionally, HNC attributes to the use of alcohol or chewing tobacco. Over the past four decades, portions of human papillomavirus (HPV)-positive HNC are increasing at an alarming rate. Identification based on the etiological factors and molecular signatures demonstrates that these neoplastic lesions belong to a distinct category that differs in pathological characteristics and therapeutic response. Slow development in HNC therapeutics has resulted in a low 5-year survival rate in the last two decades. Interestingly, HPV-positive HNC has shown better outcomes following conservative treatments and immunotherapies. This raises demand to have a pre-therapy assessment of HPV status to decide the treatment strategy. Moreover, there is no HPV-specific treatment for HPV-positive HNC patients. Accumulating evidence suggests that phytochemicals are promising leads against HNC and show potential as adjuvants to chemoradiotherapy in HNC. However, only a few of these phytochemicals target HPV. The aim of the present article was to collate data on various leading phytochemicals that have shown promising results in the prevention and treatment of HNC in general and HPV-driven HNC. The review explores the possibility of using these leads against HPV-positive tumors as some of the signaling pathways are common. The review also addresses various challenges in the field that prevent their use in clinical settings.

Nutraceutical Compounds as Sensitizers for Cancer Treatment in Radiation Therapy

The improvement of diagnostic techniques and the efficacy of new therapies in clinical practice have allowed cancer patients to reach a higher chance to be cured together with a better quality of life. However, tumors still represent the second leading cause of death worldwide. On the contrary, chemotherapy and radiotherapy (RT) still lack treatment plans which take into account the biological features of tumors and depend on this for their response to treatment. Tumor cells' response to RT is strictly-connected to their radiosensitivity, namely, their ability to resist and to overcome cell damage induced by ionizing radiation (IR). For this reason, radiobiological research is focusing on the ability of chemical compounds to radiosensitize cancer cells so to make them more responsive to IR. In recent years, the interests of researchers have been focused on natural compounds that show antitumoral effects with limited collateral issues. Moreover, nutraceuticals are easy to recover and are thus less expensive. On these bases, several scientific projects have aimed to test also their ability to induce tumor radiosensitization both in vitro and in vivo. The goal of this review is to describe what is known about the role of nutraceuticals in radiotherapy, their use and their potential application.

Inhibition of autophagy enhances the radiosensitivity of nasopharyngeal carcinoma by reducing Rad51 expression

Radiotherapy has long been considered as the mainstay of treatment for nasopharyngeal carcinoma (NPC). However, locoregional recurrence or distant metastasis may occur in some patients due to the radiation resistance of cancer cells. Autophagy plays a vital role in protecting cells against radiation. However, the mechanism of autophagy in radiation therapy remains obscure. In the present study, we demonstrated that suppression of autophagy related 5 (Atg5) aggravated ionizing radiation (IR)-induced DNA damage and apoptosis in human NPC cells without accelerating the cell cycle, whereas regulation of the cell cycle has been widely regarded as the most important determinant of IR sensitivity. Further study showed that inhibition of autophagy suppressed the mRNA expression of Rad51, a key protein of homologous recombination that has been demonstrated to play a critical role in the repair of DNA double-strand breaks induced by radiation. Moreover, suppression of Atg5 had no impact on the radiosensitivity when cells were pre-treated by the Rad51 inhibitor, and the enhanced radiosensitivity by Atg5 suppression was reversed by overexpression of Rad51 in human NPC cells. Our results suggest that inhibition of autophagy enhances the susceptibility of NPC cells to radiation by reducing Rad51 expression. Therefore, Rad51 targeted therapy may be investigated as a potential novel agent for the adjuvant treatment of traditional radiation of NPC.