Single-cell mass spectrometry studies of drug metabolism heterogeneity and primary resistance to gefitinib in non-small cell lung cancer cells

Patients with epidermal growth factor receptor(EGFR)wild-type non-small cell lung cancer(NSCLC)often show primary resistance to gefitinib therapy.It is thus necessary to study the metabolism of gefitinib in NSCLC cells to comprehensively reveal the reasons for the primary resistance of tumors.Herein,we develop a platform for studying drug metabolism heterogeneity based on single-cell mass spectrometry(sDMH-scMS)by integrating living-cell electrolaunching ionization MS(ILCEI-MS)and high-performance liquid chromatography-MS(HPLC-MS)analysis,and the primary resistance of NSCLC cells to gefitinib was studied using this platform.The ILCEI-MS analysis showed that approximately 11.9%of NSCLC single cells contained the gefitinib metabolite M11;HPLC-MS detection diluted the intensity of M11 in subpopulations and concealed the heterogeneity of drug metabolism in tumor single cells.The intensity of gefitinib in EGFR wild-type A549 cells was markedly lower than in mutant PC9 cells,and the intensity of gefitinib metabolites was significantly higher than in PC9 cells,suggesting that the primary resistance of NSCLC cells is related to gefitinib metabolism.Moreover,the combination of gefitinib and the drug-metabolizing enzyme inhibitorα-naphthoflavone was shown to overcome the primary resistance of the NSCLC cells.Overall,the results of this study are expected to be applicable for clinical drug resistance diagnosis and treatment at the single-cell level.

Pyrotinib is effective in both trastuzumab-sensitive and primary resistant HER2-positive breast tumors

Objective: Primary resistance to trastuzumab frequently occurs in human epidermal growth factor receptor 2(HER2)-positive(+) breast cancer patients and remains a clinical challenge. Pyrotinib is a novel tyrosine kinase inhibitor that has shown efficacy in the treatment of HER2+ breast cancer. However, the efficacy of pyrotinib in HER2+ breast cancer with primary trastuzumab resistance is unknown.Methods: HER2+ breast cancer cells sensitive or primarily resistant to trastuzumab were treated with trastuzumab, pyrotinib, or the combination. Cell proliferation, migration, invasion, and HER2 downstream signal pathways were analyzed. The effects of pyrotinib plus trastuzumab and pertuzumab plus trastuzumab were compared in breast cancer cells in vitro and a xenograft mouse model with primary resistance to trastuzumab.Results: Pyrotinib had a therapeutic effect on trastuzumab-sensitive HER2+ breast cancer cells by inhibiting phosphoinositide 3-kinase(PI3K)/protein kinase B(AKT) and rat sarcoma virus(RAS)/rapidly accelerated fibrosarcoma(RAF)/mitogen-activated protein kinase(MAPK)/extracellular-signal regulated kinase(ERK)pathways. In primary trastuzumab-resistant cells, pyrotinib inhibited cell growth, migration, invasion, and HER2 downstream pathways, whereas trastuzumab had no effects. The combination with trastuzumab did not show increased effects compared with pyrotinib alone. Compared with pertuzumab plus trastuzumab, pyrotinib plus trastuzumab was more effective in inhibiting cell proliferation and HER2 downstream pathways in breast cancer cells and tumor growth in a trastuzumab-resistant HER2+ breast cancer xenograft model.Conclusions: Pyrotinib-containing treatments exhibited anti-cancer effects in HER2+ breast cancer cells sensitive and with primary resistance to trastuzumab. Notably, pyrotinib plus trastuzumab was more effective than trastuzumab plus pertuzumab in inhibiting tumor growth and HER2 downstream pathways in HER2+ breast cancer with primary resistance to trastuzumab. These findings support clinical testing of the therapeutic efficacy of dual anti-HER2 treatment combining an intracellular small molecule with an extracellular antibody.

Primary study on the resistance to bacterial blight(X. oryzae)in Cecropin B gene transgenic rices

Bacterial blight (BB) is one of the major dis-eases to rice. Antibacterial Cecropin B genehas been cloned and transformed into rice. Westudied the resistance to bacterial blight inCecropin B gene transgenic rices.Rice variety JYll9 transformed withCecropin B gene by particle bombardment andprogenies were randomly planted in the field in

Prevalence and Risk Factors of Primary Drug-Resistant Tuberculosis in China

Objective To investigate the prevalence of primary drug-resistant tuberculosis（TB） and associated risk factors in China. We also explored factors contributing to the transmission of multidrug-resistant tuberculosis（MDR-TB）. Methods A total of 2794 representative, Mycobacterium tuberculosis isolates from treatment-naive patients were subjected to drug susceptibility testing, and risk factors for drug-resistant TB were analyzed. We also analyzed MDR-TB strain sublineages, drug-resistance-conferring mutations, and risk factors associated with clustered primary MDR strains. Results Among 2794 Mycobacterium tuberculosis isolates from treatment-naive patients, the prevalence of any resistance to first-line drugs was 33.2% and the prevalence of MDR-TB was 5.7%. We did not find any risk factors significantly associated with resistance to first-line drugs. The 93 primary MDR-TB isolates were classified into six sublineages, of which, 75（80.6%） isolates were the RD105-deleted Beijing lineage. The largest sublineage included 65（69.9%） isolates with concurrent deletions of RD105, RD207, and RD181. Twenty-nine（31.2%） primary MDR strains grouped in clusters; MDR isolates in clusters were more likely to have S531 L rpoB mutation. Conclusion This study indicates that primary drug-resistant TB and MDR-TB strains are prevalent in China, and multiple measures should be taken to address drug-resistant TB.

Emerging resistance vs. losing response to immune check point inhibitors in renal cell carcinoma: two differing phenomena

The introduction of immune checkpoint inhibitor (ICI) has revolutionized the treatment of metastatic renal cell carcinoma (mRCC) and has dramatically improved the outcomes of patients. The use of monotherapy or combinations of ICIs targeting PD-1/PD-L1 and CTLA-4, as well as the addition of ICIs with tyrosine kinase inhibitors, has significantly enhanced the overall survival of mRCC patients. Despite these promising results, there remains a subset of patients who either do not respond to treatment (primary resistance) or develop resistance to therapy over time (acquired resistance). Understanding the mechanisms underlying the development of resistance to ICI treatment is crucial in the management of mRCC, as they can be used to identify new targets for innovative therapeutic strategies. Currently, there is an unmet need to develop new predictive and prognostic biomarkers that can aid in the development of personalized treatment options for mRCC patients. In this review, we summarize several mechanisms of ICI resistance in RCC, including alterations in tumor microenvironment, upregulation of alternative immune checkpoint pathways, and genetic and epigenetic changes. Additionally, we highlight potential strategies that can be used to overcome resistance, such as combination therapy, targeted therapy, and immune modulation.

MODELING PRIMARY AND SECONDARY DRUG RESISTANCES UNDER CHINA^S ＂FOUR-FREE-ONE-CARE POLICY＂

We propose a mathematical model to evaluate the effect of China＇s ＂Four-Free-One-Care Policy＂ in MSM population in Beijing. We divided the drug resistant H[V patients into two sub-populations： primary drug resistance and secondary drug resistance. Uncertainty and sensitivity analysis based on Latin Hypercube Sampling （LHS） were used for these thresholds of our model. We find that drug-resistant HIV will spread fast in MSM population under China＇s current treatment policy. Especially＇, primary-resistant strain is very likely to dominate the HIV positive MSM individuals after 10 years. The conclusions hint that, China＇s outlook on HIV infections is not optimistic if sufficient kinds free second-line drugs in China cannot be put into use in the near future.

Rapamycin enhances the anti-tumor activity of cabozantinib in cMet inhibitor-resistant hepatocellular carcinoma

Cabozantinib,mainly targeting cMet and vascular endothelial growth factor receptor 2,is the second-line treatment for patients with advanced hepatocellular carcinoma(HCC).However,the lower response rate and resistance limit its enduring clinical benefit.In this study,we found that cMet-low HCC cells showed primary resistance to cMet inhibitors,and the combination of cabozantinib and mammalian target of rapamycin(mTOR)inhibitor,rapamycin,exhibited a synergistic inhibitory effect on the in vitro cell proliferation and in vivo tumor growth of these cells.Mechanically,the combination of rapamycin with cabozantinib resulted in the remarkable inhibition of AKT,extracellular signal-regulated protein kinases,mTOR,and common downstream signal molecules of receptor tyrosine kinases;decreased cyclin D1 expression;and induced cell cycle arrest.Meanwhile,rapamycin enhanced the inhibitory effects of cabozantinib on the migration and tubule formation of human umbilical vascular endothelial cells and human growth factor-induced invasion of cMet inhibitor-resistant HCC cells under hypoxia condition.These effects were further validated in xenograft models.In conclusion,our findings uncover a potential combination therapy of cabozantinib and rapamycin to combat cabozantinib-resistant HCC.