Modulation of cyclophosphamide activity by O 6-alkylguanine-DNA alkyltransferase

Purpose: The human medulloblastoma cell line D283 Med (4-HCR), a line resistant to 4-hydroperoxycyclophosphamide (4-HC), displays enhanced␣repair of DNA interstrand crosslinks induced by phosphoramide mustard. D283 Med (4-HCR) cells are cross-resistant to 1,3-bis(2-chloroethyl)-1-nitrosourea, but partial sensitivity is restored after elevated levels of O ⁶-alkylguanine-DNA alkyltransferase (AGT) are depleted by O ⁶-benzylguanine (O ⁶-BG). Studies were conducted to define the activity of 4-HC and 4-hydroperoxydidechlorocyclophosphamide against D283 Med (4-HCR) after AGT is depleted by O ⁶-BG. Methods: Limiting dilution and xenograft studies were conducted to define the activity of 4-HC and 4-hydroperoxydidechlorocyclophosphamide with or without O ⁶-BG. Results: The activity of 4-HC and 4-hydroperoxydidechlorocyclophosphamide against D283 Med (4-HCR) was increased after AGT depletion by O ⁶-BG preincubation. Similar studies with Chinese hamster ovary cells, with or without stable transfection with a plasmid expressing the human AGT protein, revealed that the AGT-expressing cells were significantly less sensitive to 4-HC and 4-hydroperoxydidechlorocyclophosphamide. Reaction of DNA with 4-HC, phosphoramide mustard, or acrolein revealed that only 4-HC and acrolein caused a decrease in AGT levels. Conclusions: We propose that a small but potentially significant part of the cellular toxicity of cyclophosphamide in these cells is due to acrolein, and that this toxicity is abrogated by removal of the acrolein adduct from DNA by AGT. Received: 17 February 1998 / Accepted: 20 May 1998     

Synthesis, characterisation, and antineoplastic cytotoxicity of hybrid naphthohydroquinone–nucleic base mimic derivatives

From a partially degraded Diels–Alder adduct of α-myrcene and 1,4-benzoquinone, several model compounds belonging to a new series of 1,4-naphthohydroquinone derivatives have been prepared. Phenyl, pyridyl, imidazolyl and some nucleic base mimic heterocycles have been attached to the naphthohydroquinone system through linkers of different size and type, leading to potentially antineoplastic hybrid structures. The new compounds have been evaluated in vitro for their cytotoxicity against cultured human cancer cells of A-549 lung carcinoma, HT-29 colon adenocarcinoma and MDA-MB-231 breast carcinoma. GI₅₀ values ranged in the μM level.     

外源性人多药耐药基因转染对兔骨髓单个核细胞生物学行为的影响

目的:观察外源性人多药耐药基因(human multidrug resistance gene 1, hMDR1)对新西兰兔骨髓单个核细胞(mononuclear cells, MNCs)生物学行为的影响.方法:用携带目的基因hMDR1和绿色荧光蛋白(green fluorescence protein, GFP)报告基因的复制缺陷型重组腺病毒(rAd-hMDR1-GFP)转染原代培养的MNCs以获取hMDR1基因修饰的MNCs (MNCs-rAd-hMDR1-GFP),荧光显微镜和FCM法检测转染效率;MTT法绘制MNCs-rAd-hMDR1-GFP细胞生长曲线;FCM检测MNCs-rAd-hMDR1-GFP细胞周期及细胞凋亡情况;RT-PCR及Western印迹法从基因和蛋白水平检测MNCs-rAd-hMDR1-GFP细胞内hMDR1的表达;柔红霉素(daunorubicin, DNR)泵出实验检测导入hMDR1基因的外排泵生理功能.结果:感染复数(multiplicity of infection, MOI)为100时,rAd-hMDR1-GFP对MNCs的转染效率为30%～35%,且不影响MNCs增殖生长;FCM结果提示,rAd-hMDR1-GFP对MNCs细胞周期及凋亡无影响(P＞0.05);rAd-hMDR1-GFP转染72 h后hMDR1转录水平和P-糖蛋白(P-glycoprotein, P-gp)表达水平均明显升高(P＜0.01),且外源性hMDR1能发挥外排泵功能(P＜0.01).结论:rAd-hMDR1-GFP能将外源性hMDR1基因高效导入兔骨髓MNCs并稳定功能性表达,不影响MNCs细胞周期、细胞凋亡及细胞增殖生长等生物学特性,为进一步研究hMDR1基因的骨髓保护作用提供实验依据.     

Molecular pharmacology and antitumor activity of Zalypsis in several human cancer cell lines

Zalypsis^® is a new synthetic alkaloid tetrahydroisoquinoline antibiotic that has a reactive carbinolamine group. This functionality can lead to the formation of a covalent bond with the amino group of selected guanines in the DNA double helix, both in the absence and in the presence of methylated cytosines. The resulting complex is additionally stabilized by the establishment of one or more hydrogen bonds with adjacent nucleotides in the opposite strand as well as by van der Waals interactions within the minor groove. Fluorescence-based thermal denaturation experiments demonstrated that the most favorable DNA triplets for covalent adduct formation are AGG, GGC, AGC, CGG and TGG, and these preferences could be rationalized on the basis of molecular modeling results. Zalypsis^®-DNA adducts eventually give rise to double-strand breaks, triggering S-phase accumulation and apoptotic cell death. The potent cytotoxic activity of Zalypsis^® was ascertained in a 24 cell line panel. The mean IC₅₀ value was 7 nM and leukemia and stomach tumor cell lines were amongst the most sensitive. Zalypsis^® administration in four murine xenograft models of human cancer demonstrates significant tumor growth inhibition that is highest in the Hs746t gastric cancer cell line with no weight loss of treated animals. Taken together, these results indicate that the potent antitumor activity of Zalypsis^® supports its current development in the clinic as an anticancer agent.     

丝裂霉素C血管外漏致皮肤溃疡的防护实验

为探讨丝裂霉素Ｃ实验性血管外漏致皮肤溃疡的防护措施，我们以０．１ｍｇ丝裂霉素Ｃ皮下注射ＢＡＬＢ／Ｃ小鼠后腿部，制成丝裂霉素Ｃ血管外漏性皮肤溃疡模型。在这模型上经８种不同药物或物理措施单独处理后１０天所产生的皮肤溃疡面积与对照组（生理盐水封闭）相比较（经ｔ检验后），差异有显著性的组分别是：外漏后及时用０．１ｍｌ９９％二甲基亚砜局部封闭或加用它在外漏表皮处外涂（Ｐ＜０．００１），０．１ｍｌ５％碳酸氢钠（Ｐ＜０．００１），０．１ｍｌ１％普鲁卡因（内含０．４％地塞米松）（Ｐ＜０．００１），０．１ｍｌ９０％二甲基亚砜（内含１０％维生素Ｅ）外涂（Ｐ＜０．０１）；外漏后半小时用０．１ｍｌ９９％二甲基亚砜封闭所产生的皮肤溃疡面积与对照组相比虽有显著差异（Ｐ＜０．０５），但溃疡防护能力较差。冰水冷敷或０．１ｍｌ１０％硫代硫酸钠（及时封闭）组与对照组相比差异无显著性（Ｐ＞０．０５）。本研究为临床上丝裂霉素Ｃ血管外漏的防护提供了药物选择的依据，文中还讨论了二甲基亚砜对丝裂霉素Ｃ外漏性皮肤溃疡防护的机理。     

The association between pre-exposure to glucocorticoids and other immunosuppressant drugs with severe COVID-19 outcomes

ObjectivesWhether preinfection use of immunosuppressant drugs is associated with COVID-19 severity remains unclear. The study was aimed to determine the association between preinfection use of immunosuppressant drugs with COVID-19 outcomes within 1 month after COVID-19 diagnosis.MethodsThis cohort study included individuals aged ≥18 years with underlying conditions associated with an immunocompromised state and diagnosed with COVID-19 between February 2020 and January 2021 at Karolinska University Hospital, Stockholm.Exposure to immunosuppressant drugs was defined based on dose and duration of drugs (glucocorticoids and drugs included in L01 or L04 chapter of Anatomical Therapeutic Chemical classification) before COVID-19 diagnosis. Outcomes included hospital admission, ICU admission, mechanical ventilation, mortality, renal failure, stroke, pulmonary embolism, and cardiac event. ORs were calculated using logistic regression and baseline covariate adjustment for confounding with inverse probability of treatment weights.ResultsOf 1067 included individuals, 444 were pre-exposed to immunosuppressive treatments before COVID-19 diagnosis (72 high-dose glucocorticoids, 255 L01 drugs (antineoplastics), 198 L04 (other immunosuppressants) and 78 to multiple drugs). There was no association between pre-exposure and hospital admission (OR 0.83, 95% CI 0.64 to 1.09) because of COVID-19. Pre-exposure to L01 or L04 drugs were not associated with hospital admission (adjusted ORs (aORs): 1.23, 0.86 to 1.76 and 1.31, 0.77 to 2.21) or other outcomes. High-dose glucocorticoids (≥20 mg/day prednisolone equivalent) were associated with hospital admission (aOR 2.50, 1.26 to 4.96), cardiac events (aOR 1.93, 1.08 to 3.46), pulmonary embolism (aOR 2.78, 1.08 to 7.15), and mortality (aOR 3.48, 1.77 to 6.86) due to COVID-19.DiscussionAntineoplastic and other immunosuppressants drugs were not associated with COVID-19 severity whereas high-dose glucocorticoids were associated. Further studies should evaluate the effect of pre-exposure of different dose of glucocorticoids on COVID-19 prognosis.     

Survey on learning needs and preferred sources of information to meet these needs in Italian oncology patients receiving chemotherapy

Cancer patient education can be especially important in topics like side effects of chemotherapy. Information needs of oncology patients are scarcely investigated in Italy. This study aimed to identify the learning needs, the amount of information desired and the preferred methods of information delivery of Italian cancer patients receiving chemotherapy. A total of 111 cancer patients completed a questionnaire developed for this study, which was assessed for validity and reliability. Respondents ranked the following priority information: illness, recovery, treatments, chemotherapy side effects and trajectory of illness. The great majority wanted to receive as much information as possible about all these topics. Most patients showed their wish to be informed along with their relatives, but only a few wanted relatives to be informed before them. The preferred method for receiving information about side effects of chemotherapy was oral conversation, followed by written information. Patients preferred receiving information from the oncologist, followed by the oncology nurse and the general practitioner. Most respondents preferred to be informed before receiving the first cycle of chemotherapy. Results are consistent with the existing literature with regard to information priorities, quantity of information desired and preferred methods of information. In contrast with a non-disclosure dominant culture, Italian cancer patients manifest their wish to be informed a great deal and personally about their condition. In order to meet cancer patients' information needs, health professionals' education and practice should be improved.     

Development and applications of a real-time quantitative RT-PCR method (QRT-PCR) for BRCA1 mRNA

OBJECTIVES: To develop a real-time quantitative RT-PCR method for BRCA1 mRNA and then use it for the study of BRCA1 gene expression in human MCF-7 breast cancer cells after their exposure to antineoplastic agents and gamma irradiation. DESIGN AND METHODS: The developed QRT-PCR method is based on the real-time monitoring of a fluorescein-labeled TaqMan probe, specific for BRCA1 mRNA, during PCR in the LightCycler. A BRCA1 PCR amplicon was purified, quantitated and used as a standard of known concentration for the development and analytical evaluation of the assay. The method was applied to study the alteration of BRCA1 gene expression after exposure to taxol, doxorubicin, 5-fluorouracil, etoposide or gamma irradiation in human MCF-7 breast cancer cells. RESULTS: The developed method is quantitative, highly specific for mRNA and highly sensitive (detection limit of 4 BRCA1 copies per mug of total RNA). We observed a reduction of BRCA1 expression for all antineoplastic agents used, while the gamma irradiated MCF-7 cells had an increase of expression with a peak at the 10 Gy dose. CONCLUSIONS: The developed BRCA1 QRT-PCR method is quantitative, highly sensitive and specific. The proposed method is rapid, automated, and cost effective and can be used to study BRCA1 expression in a variety of clinical samples.     

Self-reported taste and smell changes during cancer chemotherapy

PURPOSE: This study explores the prevalence of self-reported taste and smell changes (TSCs) during chemotherapy and relationships between TSCs and demographic and clinical factors. MATERIALS AND METHODS: Consecutive patients who had received chemotherapy for > or =6 weeks at 11 outpatient chemotherapy units completed a questionnaire developed for this survey. RESULTS: Seventy-five percent of the 518 participants reported TSCs, with TSCs more prevalent among women and younger patients. After adjustment for age and sex, we found that patients reporting TSCs more often reported: previous smell changes, less responsibility for cooking, concurrent medication, higher educational levels, and being on sick leave. Participants reporting oral problems, nausea, appetite loss, and depressed mood more frequently reported TSCs. Diagnosis and type of chemotherapy regimen did not predict TSCs. CONCLUSION: TSCs were found to be common during cancer chemotherapy and were related to sociodemographic rather than clinical factors. TSCs were also found to be closely related to many other side effects of chemotherapy.     

索拉非尼与顺铂的不同联合方案对肝癌HepG2细胞的作用研究

摘要：目的 探讨索拉非尼（Sorafenib，BAY 43-9006，Nexavar）联合顺铂（cisplatin，DDP）对肝癌细胞HepG2的杀伤作用。方法 单独、同时及序贯联合给药后以MTT法测定HepG2细胞的增殖，用流式细胞仪检测细胞凋亡。结果 索拉非尼及DDP单药对HepG2均有抑制作用，两药同时给药具有协同或相加作用（P<0. 05）。序贯用药DDP先用组与同时给药组相比疗效相似（P>0. 05），表现为协同或相加作用。而索拉非尼先用组疗效差于前两者(P<0. 05)，显示拮抗作用。联合用药组凋亡率均比单药组高（P<0. 05），同时给药组及DDP先用组凋亡率比索拉非尼先用组高（P<0. 05，P<0. 05）。结论　索拉非尼和顺铂对肝癌HepG2细胞有增殖抑制及促凋亡作用，同时给药表现为协同或相加作用，序贯联合用药产生单向协同或相加作用。