Multidrug resistance (MDR) seriously limits the clinical application of chemotherapy. A mechanism underlying MDR is the overexpression of efflux transporters associated with chemotherapeutic drugs. P‑glycoprotein (P‑gp) is an ATP‑binding cassette (ABC) transporter, which promotes MDR by pumping out chemotherapeutic drugs and reducing their intracellular concentration. To date, overexpression of P‑gp has been detected in various types of chemoresistant cancer and inhibiting P‑gp‑related MDR has been suggested. The present review summarizes the mechanisms underlying MDR mediated by P‑gp in different tumors and evaluated the related signaling pathways, with the aim of improving understanding of the current status of P‑gp‑mediated chemotherapeutic resistance. This review focuses on the main mechanisms of inhibiting P‑gp‑mediated MDR, with the aim of providing a reference for the study of reversing P‑gp‑mediated MDR. The first mechanism involves decreasing the efflux activity of P‑gp by altering its conformation or hindering P‑gp‑chemotherapeutic drug binding. The second inhibitory mechanism involves inhibiting P‑gp expression to reduce efflux. The third inhibitory mechanism involves knocking out the ABCB1 gene. Potential strategies that can inhibit P‑gp include certain natural products, synthetic compounds and biological techniques. It is important to screen lead compounds or candidate techniques for P‑gp inhibition, and to identify inhibitors by targeting the relevant signaling pathways to overcome P‑gp‑mediated MDR.

Targeted liquid chromatography-tandem mass spectrometry (LC-MS/MS) is a robust and reliable tool in quantitative analysis of pesticide residues in food samples. However, these methods have been only targeted to a predefined set of pesticides. Many other unexpected pesticides and/or their (bio)transformation products present in food matrices that may be harmful to consumers need to be discovered for food safety monitoring purpose. Therefore, non-targeted screening approaches using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) have gained much attention in food monitoring recently. However, the development and implementation of non-targeted screening of potential pesticides and their (bio)transformation products in food samples are particularly challenging due to the inherent sample complexity and large quantity of MS data. To provide guidance on how to use non-targeted screening approaches for pesticide screening, three different aspects, namely, sample preparation, data acquisition and data processing, encompassed in the workflow of non-targeted screening approaches have been discussed, and current strategies, advances and challenges regarding these three aspects are reviewed. In addition, the recent application of non-targeted screening analysis of pesticide residues and their (bio)transformation products in food samples has been overviewed in this paper.

Chronic stress has a substantial influence on the tumor microenvironment (TME), leading to compromised effectiveness of anti-cancer therapies through diverse mechanisms. It disrupts vital functions of immune cells that play a critical role in anti-tumor immunity, such as the inhibition of dendritic cells (DCs) and lymphocytes, while simultaneously enhancing the activity of immune cells that support tumor growth, such as myeloid-derived suppressor cells and tumor-associated macrophages. Furthermore, chronic stress exerts a significant impact on crucial mechanisms within the TME, including angiogenesis, DNA repair, hypoxia, extracellular matrix deposition, and tumor metabolism. These alterations in the TME, induced by stress, result from the activation of the hypothalamic–pituitary–adrenal axis and sympathetic nervous system, in conjunction with epigenetic modifications. In conclusion, chronic stress significantly influences the TME and impedes the efficacy of anti-cancer treatments, underscoring the importance of targeting stress pathways to improve therapeutic results.