Adaptation to Endoplasmic Reticulum Stress Enhances Resistance of Oral Cancer Cells to Cisplatin by Up-Regulating Polymerase η and Increasing DNA Repair Efficiency

Endoplasmic reticulum (ER) stress response is an adaptive program to cope with cellular stress that disturbs the function and homeostasis of ER, which commonly occurs during cancer progression to late stage. Late-stage cancers, mostly requiring chemotherapy, often develop treatment resistance. Chemoresistance has been linked to ER stress response; however, most of the evidence has come from studies that correlate the expression of stress markers with poor prognosis or demonstrate proapoptosis by the knockdown of stress-responsive genes. Since ER stress in cancers usually persists and is essentially not induced by genetic manipulations, we used low doses of ER stress inducers at levels that allowed cell adaptation to occur in order to investigate the effect of stress response on chemoresistance. We found that prolonged tolerable ER stress promotes mesenchymal–epithelial transition, slows cell-cycle progression, and delays the S-phase exit. Consequently, cisplatin-induced apoptosis was significantly decreased in stress-adapted cells, implying their acquisition of cisplatin resistance. Molecularly, we found that proliferating cell nuclear antigen (PCNA) ubiquitination and the expression of polymerase η, the main polymerase responsible for translesion synthesis across cisplatin-DNA damage, were up-regulated in ER stress-adaptive cells, and their enhanced cisplatin resistance was abrogated by the knockout of polymerase η. We also found that a fraction of p53 in stress-adapted cells was translocated to the nucleus, and that these cells exhibited a significant decline in the level of cisplatin-DNA damage. Consistently, we showed that the nuclear p53 coincided with strong positivity of glucose-related protein 78 (GRP78) on immunostaining of clinical biopsies, and the cisplatin-based chemotherapy was less effective for patients with high levels of ER stress. Taken together, this study uncovers that adaptation to ER stress enhances DNA repair and damage tolerance, with which stressed cells gain resistance to chemotherapeutics.     

Sensitization of MCF7 Cells with High Notch1 Activity by Cisplatin and Histone Deacetylase Inhibitors Applied Together

Histone deacetylase inhibitors (HDIs) are promising anti-cancer agents that inhibit proliferation of many types of cancer cells including breast carcinoma (BC) cells. In the present study, we investigated the influence of the Notch1 activity level on the pharmacological interaction between cisplatin (CDDP) and two HDIs, valproic acid (VPA) and suberoylanilide hydroxamic acid (SAHA, vorinostat), in luminal-like BC cells. The type of drug–drug interaction between CDDP and HDIs was determined by isobolographic analysis. MCF7 cells were genetically modified to express differential levels of Notch1 activity. The cytotoxic effect of SAHA or VPA was higher on cells with decreased Notch1 activity and lower for cells with increased Notch1 activity than native BC cells. The isobolographic analysis demonstrated that combinations of CDDP with SAHA or VPA at a fixed ratio of 1:1 exerted additive or additive with tendency toward synergism interactions. Therefore, treatment of CDDP with HDIs could be used to optimize a combined therapy based on CDDP against Notch1-altered luminal BC. In conclusion, the combined therapy of HDIs and CDDP may be a promising therapeutic tool in the treatment of luminal-type BC with altered Notch1 activity.     

Sensitivity to Cisplatin in Head and Neck Cancer Cells Is Significantly Affected by Patient-Derived Cancer-Associated Fibroblasts

Cancer-associated fibroblasts (CAFs) are one of the most abundant and critical components of the tumor stroma. CAFs can impact many important steps of cancerogenesis and may also influence treatment resistance. Some of these effects need the direct contact of CAFs and cancer cells, while some involve paracrine signals. In this study, we investigated the ability of head and neck squamous cell carcinomas (HNSCC) patient-derived CAFs to promote or inhibit the colony-forming ability of HNSCC cells. The effect of cisplatin on this promoting or inhibiting influence was also studied. The subsequent analysis focused on changes in the expression of genes associated with cancer progression. We found that cisplatin response in model HNSCC cancer cells was modified by coculture with CAFs, was CAF-specific, and different patient-derived CAFs had a different “sensitizing ratio”. Increased expression of VEGFA, PGE2S, COX2, EGFR, and NANOG in cancer cells was characteristic for the increase of resistance. On the other hand, CCL2 expression was associated with sensitizing effect. Significantly higher amounts of cisplatin were found in CAFs derived from patients who subsequently experienced a recurrence. In conclusion, our results showed that CAFs could promote and/or inhibit colony-forming capability and cisplatin resistance in HNSCC cells via paracrine effects and subsequent changes in gene expression of cancer-associated genes in cancer cells.     

枸杞多糖对顺铂诱导小鼠睾丸支持细胞凋亡的影响

目的：研究枸杞多糖（lycium barbarum polysaccharides, LBP）对顺铂（cis-dichlorodiamineplatinum, CDDP）诱导小鼠睾丸支持细胞（TM4）凋亡的影响并探讨其可能机制。方法：体外培养TM4细胞,四甲基偶氮噻唑蓝（MTT）法检测LBP对CDDP诱导TM4细胞生存率的影响,Western blot检测LBP对CDDP诱导TM4细胞凋亡相关基因Bcl-2、Bax和Caspase-3蛋白表达的影响,流式细胞仪检测细胞凋亡率的变化。结果：与Control组相比,CDDP组TM4细胞凋亡显著增加,细胞内抑凋亡基因Bcl-2表达量显著降低,促凋亡基因Bax表达量及Caspase-3表达量显著升高;与CDDP组相比,CDDP+LBP组TM4细胞凋亡显著减少,细胞内抑凋亡基因Bcl-2表达量显著升高,促凋亡基因Bax表达量及Caspase-3表达量显著降低。 结论：LBP作用于CDDP诱导的TM4细胞,能够通过增强细胞内Bcl-2的表达,抑制Bax及Caspase-3的表达来阻抑因CDDP诱导的TM4细胞凋亡,进而减轻CDDP对TM4细胞造成的损伤。     

顺铂联合长春瑞滨同步放化疗治疗局部晚期非小细胞肺癌的长期疗效

目的 探讨顺铂联合长春瑞滨（NP方案）同步放疗治疗局部晚期非小细胞肺癌的长期疗效及毒副作用.方法 随访57例NP方案同步放化疗病例.NP方案为长春瑞滨25 mg·m-2,第1、8天;顺铂25 mg·m-2第1-3天,21 d为1个周期.放疗采用适形放疗,总剂量为60～70 Gy,6～7周完成放疗.同步放化疗于放疗第1天开始,放疗期间共行2个周期化疗,放疗结束后继续接受2个周期化疗.观察治疗后1、3、5年的无复发生存期（PFS）和总生存期（OS）及晚期毒副作用（肺毒性、食管毒性）.结果 同步放化疗后客观缓解率为80.7%,1、3、5年无进展生存率为51.8%、22.2%、16.7%,相应的总生存率为80.5%、37.3%和21.0%;中位无进展生存时间、总生存时间分别为12.8和29.9个月.1级、2级、3级晚期肺毒副作用分别为14例、12例、5例,无4级和5级晚期肺毒副作用,26例（45.6%）未见晚期毒副作用.晚期食管毒副作用3例,均为1级反应,无2级以上食管晚期毒副作用.结论 顺铂联合长春瑞滨同步放化疗治疗局部晚期非小细胞肺癌的长期疗效显著,且毒副作用可耐受.     

牛磺酸对顺铂引起的小鼠肾髓质ATP酶活性变化的影响

目的 :探讨牛磺酸对顺铂引起的小鼠肾髓质ATP酶活性的影响 ;方法 :4 0只小鼠随机分为正常对照组、CDDP组、牛磺酸 2 0 0mg组 (Tau2 0 0 )和牛磺酸 4 0 0mg组 (Tau4 0 0 ) ,分取肾髓质、制备匀浆 ,用生化法测定Na ,K -ATP酶、Ca2 -ATP酶和Mg2 -ATP酶活性 ;结果 :CDDP组、Tau2 0 0组、Tau4 0 0组肾髓质Na ,K -ATP酶、Ca2 -ATP酶和Mg2 -ATP酶活性均明显低于正常对照组 (P <0 .0 1)。Tau2 0 0组、Tau4 0 0组肾髓质Na ,K -ATP酶和Ca2 -ATP酶活性均明显高于CDDP组 (P <0 .0 1或P <0 .0 5 ) ,而Mg2 -ATP酶活性与CDDP组相比无显著差别 (P >0 .0 5 ) ;结论 :牛磺酸可明显增加肾髓质Na ,K -ATP酶和Ca2 -ATP酶活性 ,对顺铂引起的肾毒性具有防治作用。     

A Preliminary Study of the Toxicological Properties of Selected Polymer–Ferrocene Conjugates

Prompted by early observations of the cytotoxic and antineoplastic properties of certain ferrocene and ferricenium derivatives, efforts in this laboratory were focused on the synthesis of carrier-bound ferrocene compounds. Subsequent cell culture tests carried out with selected conjugates obtained in that program showed these polymers to be highly active antiproliferative agents. In the present project toxicological work has been performed in vivo on several ferrocene conjugates in an effort to assess their toxic effects in experimental animals (CD-1 mice). The conjugates, all based on an ,-DL-polyaspartamide backbone structure, comprise the ferrocene drug model as a terminal on short side chains containing biofissionable amide or ester links for intracellular drug release. The polymers, dissolved in phosphate-buffered saline, have been injected in predetermined concentrations into the vein of the mice, and the maximum tolerated dose (MTD) levels have been determined, the latter referring to the highest dose levels administered that would allow long-term survival of the test animals. For the five conjugates tested, MTD levels range from about 3 to 30 mg Fe/kg or 0.05–0.66 mmol Fe/kg. Compared on a molar metal-to-metal basis with similarly structured platinum conjugates tested previously (MTD, 0.14–2.66 mmol Pt/kg), these values are indicative of comparatively high toxicity of the ferrocene polymers. Some implications of these findings are discussed.