Pawlak Alicja, Ziolo Ewa, Fiedorowicz Anna, Fidyt Klaudyna, Strzadala Leon, Kalas Wojciech
Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Rudolfa Weigla 12, 53-114, Wroclaw, Poland.
Jan Dlugosz University in Czestochowa, Waszyngtona 4/8, 42-200, Czestochowa, Poland.
BMC Cancer. 2016 Nov 16;16(1):893. doi: 10.1186/s12885-016-2925-6.
The currently approved therapies fail in a substantial number of colorectal cancer (CRC) patients due to the molecular heterogeneity of CRC, hence new efficient drug combinations are urgently needed. Emerging data indicate that 5-azanucleosides are able to sensitize cancer cells to the standard chemotherapeutic agents and contribute to overcoming intrinsic or acquired chemoresistance.
CRC cells with different genetic backgrounds (HCT116, DLD-1, HT-29) were sequentially treated with 5-azanucleosides and topoisomerase inhibitors. The combined effects of these two drug classes on cell viability, apoptosis, signaling pathways, and colony formation were investigated.
Here, we demonstrate that pretreatment with DNA demethylating agents, 5-aza-2'-deoxycytidine and 5-azacytidine, sensitizes CRC cells to topoisomerase inhibitors (irinotecan, etoposide, doxorubicin, mitoxantrone), reducing cell viability and clonogenicity and increasing programmed cell death more effectively than individual compounds at the same or even higher concentrations. 5-Azanucleosides did not cause considerable immediate toxic effects as evaluated by analysis of cell viability, apoptosis, DNA damage (γH2A.X), and endoplasmic reticulum (ER) stress (CHOP). However, 5-azanucleosides exerted long-lasting effects, reducing cell viability, changing cell morphology, and affecting phosphoinositide 3-kinase (PI3-kinase)/Akt signaling pathway. We found that a single exposure to 5-azanucleosides is sufficient to induce long-lasting sensitization to topoisomerase inhibitors. The combinatorial, but not separate, treatment with low doses of 5-aza-2'-deoxycytidine (0.1 μM) and etoposide (0.5 μM) caused a long-lasting (almost 70 days) reduction in clonogenic/replating ability of DLD-1 cells.
These results suggest that sequential treatments with DNA demethylating agents and topoisomerase inhibitors may exert clinically relevant anticancer effects.
由于结直肠癌（CRC）的分子异质性，目前批准的治疗方法在相当数量的CRC患者中失效，因此迫切需要新的有效药物组合。新出现的数据表明，5-氮杂核苷能够使癌细胞对标准化疗药物敏感，并有助于克服内在或获得性化疗耐药性。
用5-氮杂核苷和拓扑异构酶抑制剂依次处理具有不同遗传背景的CRC细胞（HCT116、DLD-1、HT-29）。研究了这两类药物对细胞活力、凋亡、信号通路和集落形成的联合作用。
在此，我们证明，用DNA去甲基化剂5-aza-2'-脱氧胞苷和5-氮杂胞苷预处理可使CRC细胞对拓扑异构酶抑制剂（伊立替康、依托泊苷、阿霉素、米托蒽醌）敏感，与相同或更高浓度的单一化合物相比，更有效地降低细胞活力和克隆形成能力，并增加程序性细胞死亡。通过分析细胞活力、凋亡、DNA损伤（γH2A.X）和内质网（ER）应激（CHOP）评估，5-氮杂核苷不会引起相当大的即时毒性作用。然而，5-氮杂核苷具有持久作用，可降低细胞活力、改变细胞形态并影响磷酸肌醇3-激酶（PI3-激酶）/Akt信号通路。我们发现单次暴露于5-氮杂核苷足以诱导对拓扑异构酶抑制剂的持久敏感性。低剂量的5-aza-2'-脱氧胞苷（0.1μM）和依托泊苷（0.5μM）联合（而非单独）处理导致DLD-1细胞的克隆/再接种能力长期（近70天）降低。
这些结果表明，DNA去甲基化剂和拓扑异构酶抑制剂的序贯治疗可能发挥临床相关的抗癌作用。
