Concomitance of P-gp/LRP Expression with EGFR Mutations in Exons 19 and 21 in Non-Small Cell Lung Cancers

Integrated microbiome and metabolome analysis reveals synergistic efficacy of basil polysaccharide and gefitinib in lung cancer through modulation of gut microbiota and fecal metabolites

Emerging evidence suggests that gut microbiota and its metabolites significantly influence the effectiveness of EGFR-TKIs (e.g., gefitinib, erlotinib) in lung cancer treatment. Plant polysaccharides can interact with gut microbiota, leading to changes in the host-microbe metabolome that may affect drug metabolism and therapeutic outcomes. Our previous research demonstrated the efficacy of basil polysaccharide (BPS) in treating various cancers by regulating hypoxic microenvironment and inhibiting epithelial-mesenchymal transition process. However, the potential impact of BPS on gut microbiota has not been thoroughly explored. In this study, we employed an immunodeficient gefitinib-resistant xenograft mouse model to explore whether BPS enhances the antitumor effects of gefitinib. A multi-omics approach, including 16S rDNA amplicon sequencing and LC-MS, was used to elucidate these synergistic effects. Our findings indicate that BPS can enhance tumor responsiveness to gefitinib by modulating the gut microbiota and its metabolites through multiple metabolic pathways. These changes in gut microbiota and metabolites could potentially affect cancer related signaling pathway and lung resistance-related protein, which are pivotal in determining the efficacy of EGFR-TKIs in cancer treatment.

Overexpression of ABCB1 Associated With the Resistance to the KRAS-G12C Specific Inhibitor ARS-1620 in Cancer Cells

The KRAS-G12C inhibitor ARS-1620, is a novel specific covalent inhibitor of KRAS-G12C, possessing a strong targeting inhibitory effect on KRAS-G12C mutant tumors. Overexpression of ATP-binding cassette super-family B member 1 (ABCB1/P-gp) is one of the pivotal factors contributing to multidrug resistance (MDR), and its association with KRAS mutations has been extensively studied. However, the investigations about the connection between the inhibitors of mutant KRAS and the level of ABC transporters are still missing. In this study, we investigated the potential drug resistance mechanism of ARS-1620 associated with ABCB1. The desensitization effect of ARS-1620 was remarkably intensified in both drug-induced ABCB1-overexpressing cancer cells and ABCB1-transfected cells as confirmed by cell viability assay results. This desensitization of ARS-1620 could be completely reversed when co-treated with an ABCB1 reversal agent. In mechanism-based studies, [³H] -paclitaxel accumulation assay revealed that ARS-1620 could be competitively pumped out by ABCB1. Additionally, it was found that ARS-1620 remarkably stimulated ATPase activity of ABCB1, and the HPLC drug accumulation assay displayed that ARS-1620 was actively transported out of ABCB1-overexpressing cancer cells. ARS-1620 acquired a high docking score in computer molecular docking analysis, implying ARS-1620 could intensely interact with ABCB1 transporters. Taken all together, these data indicated that ARS-1620 is a substrate for ABCB1, and the potential influence of ARS-1620-related cancer therapy on ABCB1-overexpressing cancer cells should be considered in future clinical applications.

Research progress on the relationship between lung cancer drug-resistance and microRNAs

Lung cancer, a malignant tumor with the highest death rate of cancer, seriously endangers human health. And its pathogenesis and mechanism of drug resistance has been partially clarified, especially for the signal pathway of epidermal growth factor receptor (EGFR). The targeting therapy of EGFR signaling pathway in non-small cell lung cancer (NSCLC) has achieved a certain effect, but the two mutation of EGFR and other mechanisms of lung cancer resistance still greatly reduce the therapeutic effect of chemotherapy on it. MicroRNA is an endogenous non coding RNA, which has a regulatory function after transcriptional level. Recent studies on the mechanism of lung cancer resistance have found that a variety of microRNAs are related to the mechanism of lung cancer drug-resistance. They can regulate lung cancer resistance by participating in signal pathways, drug resistance genes and cell apoptosis, thus affecting the sensitivity of cancer cells to drugs. Therefore, microRNAs can be used as a specific target for the treatment of lung cancer and plays a vital role in the early diagnosis, prognosis and treatment of lung cancer. This article reviews the mechanisms of lung cancer resistance and its relationship with microRNAs.

Multidrug resistance affects the prognosis of primary epithelial ovarian cancer

Multidrug-resistant tumor cells can tolerate different structures, functions and antidrug action mechanisms, therefore, allowing these cells to respond to various structurally unrelated mechanisms of different chemotherapy drugs and to exhibit cross-resistance. The present study aimed to investigate the role of Multi-drug resistance gene (MDR1), Placental glutathione S-transferase-P1 (GSTP1), Lung resistance protein (LRP) and Ras association domain family member 1 (RASSF1A) in primary epithelial ovarian cancer (PEOC). The mRNA (protein) expression levels of MDR1, product P glycoprotein, LRP and GSTP1 were evaluated with reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and western blot analysis in all tissue samples, ovarian cancer cell line A2780 and A2780/DDP. Methylation-specific PCR (MSP) was used to detect RASSF1A gene methylation in all tissue samples. The resistance genes/proteins were either poorly or not expressed in A2780, however were highly expressed in A2780/DDP cell line. The expression of resistance genes/proteins decreased following different concentrations of zebularine-stimulated A2780/DDP. Hypermethylation and low expression of RASSF1A gene were detected in PEOC and A2780/DDP. Subsequent to being exposed to different concentrations of zebularine-stimulated A2780/DDP, the RASSF1A methylation level was decreased, while the unmethylation level was increased. The expression of RASSF1A gene/protein was gradually restored, and the gene/protein expression was enhanced with the increase in drug concentration. Multivariate logistic regression indicated that the expression level of gene LRP and GSTP1 was a risk factor for PEOC prognosis. Furthermore, the expression of LRP and GSTP1 in the negative-group survival curves was higher compared with the positive group. High expression of resistance genes may serve an important role in cancer primary resistance. Low expression caused by hyper-methylation of RASSF1A gene may serve an important role in cancer-acquired resistance in PEOC. The present study suggested that resistant gene expression may be a potential prognostic biomarker.

The CK2 inhibitor CX4945 reverses cisplatin resistance in the A549/DDP human lung adenocarcinoma cell line

Lung cancer negatively impacts global health, and the incidence of non-small cell lung cancer (NSCLC) is highest among all forms of lung cancer. Chemotherapy failure mainly occurs due to drug resistance; however, the associated molecular mechanism remains unclear. Casein kinase II (CK2), which plays important roles in the occurrence, development and metastasis of many tumours, regulates Wnt signaling by modulating β-catenin expression. In the present study the effects of the CK2 inhibitor, CX4945 on cisplatin [or cis-diamminedichloroplatinum (II); (DDP)]-resistant A549 cells (A549/DDP) were investigated to elucidate the underlying molecular mechanism. A549/DDP cells were divided into four groups (blank control, CX4945, cisplatin and CX4945+cisplatin). Cisplatin resistance was 5.16-fold greater in A549/DDP cells compared with that in A549 cells, with an optimal cisplatin concentration of 5 µg/ml. Moreover, levels of CK2, dishevelled-2 (DVL-2) phosphorylated (p) at Ser143 (p-DVL-2^Ser143), and major Wnt-signaling proteins were significantly higher in A549/DDP cells compared with that in A549 cells (P<0.05), with these levels further increased following cisplatin treatment (P<0.05), whereas these levels significantly decreased in A549 cells after cisplatin treatment (P<0.05). Additionally, multidrug-resistance-associated protein 1 and lung resistance protein expression was significantly higher in A549/DDP cells compared with that in A549 cells (P<0.05), with these levels increasing further in A549/DDP (P<0.05) but not A549 cells upon cisplatin treatment (P>0.05). In addition, reduced expression of resistance proteins in A549/DDP cells was accompanied by a decline in the 50% growth inhibition after CX4945 pre-treatment. Furthermore, levels of p-DVL-2^Ser143 and major Wnt-signaling proteins decreased significantly after treatment of A549/DDP cells with CX4945+cisplatin, whereas DVL-2 and p-DVL-2^Thr224 levels remained unchanged. Additionally, significant elevations in apoptosis rates in the CX4945+cisplatin group relative to the control and cisplatin-only groups, was observed (P<0.001). These results suggested that inhibiting Wnt/β-catenin signaling with CX4945, which attenuates levels of drug-resistance-associated proteins and induces apoptosis, might reverse cisplatin resistance in NSCLC.

Potential Regulation Mechanisms of P-gp in the Blood-Brain Barrier in Hypoxia

The blood-brain barrier (BBB) is a barrier of the central nervous system (CNS), which can restrict the free exchange of substances, such as toxins and drugs, between cerebral interstitial fluid and blood, keeping the relative physiological stabilization. The brain capillary endothelial cells, one of the structures of the BBB, have a variety of ATP-binding cassette transporters (ABC transporters), among which the most widely investigated is Pglycoprotein (P-gp) that can efflux numerous substances out of the brain. The expression and activity of P-gp are regulated by various signal pathways, including tumor necrosis factor-α (TNF-α)/protein kinase C-β (PKC- β)/sphingosine-1-phosphate receptor 1 (S1P), vascular endothelial growth factor (VEGF)/Src kinase, etc. However, it remains unclear how hypoxic signaling pathways regulate the expression and activity of P-gp in brain microvascular endothelial cells. According to previous research, hypoxia affects the expression and activity of the transporter. If the transporter is up-regulated, some drugs enter the brain's endothelial cells and are pumped back into the blood by transporters such as P-gp before they enter the brain tissue, consequently influencing the drug delivery in CNS; if the transporter is down-regulated, the centrally toxic drug would enter the brain tissue and cause serious adverse reactions. Therefore, studying the mechanism of hypoxia-regulating P-gp can provide an important reference for the treatment of CNS diseases with a hypoxia/reoxygenation (H/R) component. This article summarized the mechanism of regulation of P-gp in BBB in normoxia and explored that of hypoxia.

Expression of resistance gene and prognosis of chemotherapy in primary epithelial ovarian cancer

The sensitivity of tumor cells to chemotherapy drugs may become attenuated accounts for various reasons. Reduced drug sensitivity may cause the failure of chemotherapy and affect the prognosis of patients with cancer. This study investigates the relationship between the expression levels of lung resistance protein (LRP) and placental glutathione S-transferase-P1 (GSTP1), the resistance of primary epithelial ovarian cancer (PEOC) to chemotherapy, and the prognosis of patients with platinum drug-resistant PEOC.Quantitative PCR (QT-PCR) was used to detect the mRNA level of the resistance genes LRP, GSTP1 in all tissue and cell lines.The expression levels of resistance gene (LRP, GSTP1) in PEOC were the highest, followed by borderline adenoma tissues, and the lowest levels found in benign tumor tissues, the difference of genes expression between different tissues was statistically significant; the difference between the expression rates and relative expression level of drug resistance genes was statistically significant in platinum sensitive group compare with the platinum resistant group. The difference between resistant gene negative-expression and positive-expression of chemotherapy efficiency, disease free survival time, and recurrence time were statistically significant. The resistant genes expression in the PEOC patients of the negative-group survival curves was higher than that in the positive group. With ascites non-cellular component (ANCC) stimulated SKOV3 cells, the cell proliferation inhibition rate (CPIR) increased, and with ANCC stimulated SKOV3/DDP, the expression of LRP and GSTP1 also increased.ANCC may promote the expression of drug resistance genes, and the expression of genes may predict the poorly prognosis of epithelial ovarian cancer.