MDM2 rs2279744 and TP53 rs1042522 polymorphisms associated with etoposide- and cisplatin-induced grade III/IV neutropenia in Chinese extensive-stage small-cell lung cancer patients

Genetic Polymorphisms and Platinum-Based Chemotherapy-Induced Toxicities in Patients With Lung Cancer: A Systematic Review and Meta-Analysis

Background: Platinum-based agents, including cisplatin, carboplatin, and oxaliplatin, are indispensable for the treatment of lung cancer. The development of toxicity frequently necessitates dose reduction or discontinuation of therapy, despite the clinical response. Pharmacogenomics studies were reviewed to identify the possible genetic variants that underlie individual susceptibility to platinum-related toxicities. Method: We conducted a systematic search in PubMed and Embase for pharmacogenomics reports that focused on commonly reported platinum-induced toxicities, such as gastrointestinal (GI), hematological, neurological, and other toxicities, in patients diagnosed with lung cancer. Meta-analyses were conducted to determine the association between genetic polymorphisms and platinum-induced toxicity by checking the odds ratio (OR) and 95% confidence interval (CI) using random or fixed-effects models as appropriate. Results: Twenty eligible studies that met the inclusion criteria with sufficient data were extracted and presented comprehensively. A total of 16 polymorphisms from 11 genes were included in the meta-analysis. MTHFR rs1801131 and MDM2 rs1690924 were significantly correlated with platinum-induced GI toxicity (P = 0.04 and P = 0.02, respectively). Patients with the MTHFR rs1801131AA and MDM2 rs1690924TC/CC genotype tended to have a higher risk of GI toxicity than patients with other genotypes did (OR = 1.73, 95% CI = 0.86-2.18; and OR = 0.51, 95% CI = 0.29-0.88, respectively). Compared to carriers of the MTHFR rs1801133CC genotype, carriers of the CT/TT genotype had a significantly increased risk of hematological toxicity (P = 0.01, OR = 1.68, 95% CI = 1.12-2.52). Conclusion: In the future, physicians should pay careful attention to MTHFR and MDM2 for personalized chemotherapy treatment among patients with lung cancer.

The p53 R72P polymorphism does not affect the physiological response to ionizing radiation in a mouse model

Tissue culture and mouse model studies show that the presence of the arginine (R) or proline (P) coding single nucleotide polymorphism (SNP) of the tumor suppressor gene p53 at codon 72 (p53 R72P) differentially affects the responses to genotoxic insult. Compared to the P variant, the R variant shows increased apoptosis in most cell cultures and mouse model tissues in response to genotoxins, and epidemiological studies suggest that the R variant may enhance cancer survival and reduce the risks of adverse reactions to genotoxic cancer treatment. As ionizing radiation (IR) treatment is often used in cancer therapy, we sought to test the physiological effects of IR in mouse models of the p53 R72P polymorphism. By performing blood counts, immunohistochemical (IHC) staining and survival studies in mouse populations rigorously controlled for strain background, sex and age, we discovered that p53 R72P polymorphism did not differentially affect the physiological response to IR. Our findings suggest that genotyping for this polymorphism to personalize IR therapy may have little clinical utility.

pH sensitive nano layered double hydroxides reduce the hematotoxicity and enhance the anticancer efficacy of etoposide on non-small cell lung cancer

Etoposide (VP16), used for the treatment of many carcinomas, can cause leukopenia, thrombocytopenia and hair loss. To overcome the side effects and achieve target therapy, layered double hydroxides (LDHs), a pH sensitive layered double hydroxide nanohybrid, was used here as a nano-carrier. The functions of LDHs-VP16 on non-small cell lung cancer (NSCLC) were firstly explored both in vitro and in vivo. In A549 cell line, LDH-VP16 induced apoptosis 2.3-fold as that of plain VP16 by targeting to mitochondrial, stocking cells in G1 phase. The cellular uptake demonstrated the delivery of LDH for VP16 to pass through the membrane and accumulate in mitochondria. As a carrier, LDH greatly decreased the liver toxicity and hematotoxicity of VP16. The detected liver parameters, including glutamic-oxaloacetic transaminase (AST), alkaline phosphatase (ALP), alanine aminotransferase (ALT), were all turn back to normal range after the delivery of LDH, except ALP. In vivo, LDH-VP16 reduced A549 tumor growth significantly by 60.5%, whereas native VP16 exerted no significant anticancer activity. In LDH-VP16 treated mice, the AUC was increased by 6.26 folds as the native drug, and t1/2 of LDH-VP16 was prolonged from 6.68 to 98.78h. LDH-VP16 showed a targeting effect, which largely increase the concentration in tumor and lung. The phosphorylation antibody array and Western Blot of proteins from xenografts revealed that PI3K-AKT signaling was suppressed in the LDH-VP16 treated tumor, while in VP16 treated mice, ERBB signaling pathway was involved. These results suggested that LDH-VP16 diminishes hematotoxicity, targets NSCLC tumor, performs more effectively than VP16, and different signaling pathway is involved compared to VP16.

STATEMENT OF SIGNIFICANCE

This paper explored that nano-sized layered double hydroxide (LDH) could be used as a pH sensitive delivery system to overcome hematotoxicity and enhance the bioavailability and anticancer efficacy of etoposide (VP16) against non small cell lung cancer, which was not reported before, as the best of our knowledge. We found that the liver and hematotoxicity is nearly recovered after the loading of VP16 in pH sensitive LDH, which prongs the half time from 6.68h to 98h, helps target VP16 to tumor and lung, and protects white blood cells by its pH sensitive and nano-size property. LDH-VP16 achieve markedly performance on non-small cell lung cancer by targeting to mitochondria of A549 cells in vitro and effectively inhibiting the PI3K-AKT signaling pathway in vivo. The inhibition ratio of VP16 on A549 tumor growth is increased from less than 20% (no significance compared to control) to 60.5% after the delivery of LDH. This work provides a novel system for the safe and efficient use of etoposide on non-small cell lung cancer and explores the mechanism of the function of nano carrier in cancer therapy both in vitro and in vivo.

Polymorphisms of p53 and MDM2 genes are associated with severe toxicities in patients with non-small cell lung cancer

Adverse events in platinum-based chemotherapy for patients with advanced non-small cell lung cancer (NSCLC) are major challenges. In this study, we investigated the role of the p53 and MDM2 genes in predicting adverse events in NSCLC patients treated with platinum-based chemotherapy. Specifically, we examined the p53 p. Pro72Arg (rs1042522), MDM2 c.14 + 309T>G (rs2279744) and MDM2 c.- 461C > G (rs937282) polymorphisms using PCR-based restriction fragment length polymorphism (RFLP) in 444 NSCLC patients. We determine that MDM2 c.14 + 309T > G was significantly associated with severe hematologic and overall toxicities for advanced NSCLC patients treated with platinum-based chemotherapy, especially for patients aged 57 and younger. This was also true for patients with adenocarcinoma. Second, we determine that severe gastrointestinal toxicities in patients with heterozygous MDM2 c.-461C > G were significantly higher than in patients with the G/G genotype. Third, patients with the MDM2 c.-461C > G - c.14 + 309T > G CT haplotype show much higher toxicities than those of CG haplotype. Moreover, patients carrying the MDM2 c.-461 > G -c.14 + 309T > G CG/CT diplotype exhibited higher toxicities than those carrying CG/CG. Fourth, we found that the p53 p. Pro72Arg polymorphism interacts with both age and genotype. In addition, no significant associations were observed between the 3 SNPs and the response to first-line platinum-based chemotherapy in advanced NSCLC patients. In summary, we found that the p53 p. Pro72Arg, MDM2 c.14 + 309T > G and MDM2 c.-461C > G polymorphisms are associated with toxicity risks following platinum-based chemotherapy treatment in advanced NSCLC patients. We suggest that MDM2 c.14 + 309T > G may be used as a candidate biomarker to predict adverse events in advanced NSCLC patients who had platinum-based chemotherapy treatment.