title: High DNA methyltransferase 3B expression mediates 5-aza-deoxycytidine hypersensitivity in testicular germ cell tumors.
abstract: Testicular germ cell tumors (TGCT) are the most common solid tumors of 15- to 35-year-old men. TGCT patients are frequently cured with cytotoxic cisplatin-based therapy. However, TGCT patients refractory to cisplatin-based chemotherapy have a poor prognosis, as do those having a late relapse. Pluripotent embryonal carcinomas (EC) are the malignant counterparts to embryonic stem cells and are considered the stem cells of TGCTs. Here, we show that human EC cells are highly sensitive to 5-aza-deoxycytidine (5-aza-CdR) compared with somatic solid tumor cells. Decreased proliferation and survival with low nanomolar concentrations of 5-aza-CdR is associated with ATM activation, H2AX phosphorylation, increased expression of p21, and the induction of genes known to be methylated in TGCTs (MGMT, RASSF1A, and HOXA9). Notably, 5-aza-CdR hypersensitivity is associated with markedly abundant expression of the pluripotency-associated DNA methyltransferase 3B (DNMT3B) compared with somatic tumor cells. Knockdown of DNMT3B in EC cells results in substantial resistance to 5-aza-CdR, strongly indicating that 5-aza-CdR sensitivity is mechanistically linked to high levels of DNMT3B. Intriguingly, cisplatin-resistant EC cells retain an exquisite sensitivity to low-dose 5-aza-CdR treatment, and pretreatment of 5-aza-CdR resensitizes these cells to cisplatin-mediated toxicity. This resensitization is also partially dependent on high DNMT3B levels. These novel findings indicate that high expression of DNMT3B, a likely byproduct of their pluripotency and germ cell origin, sensitizes TGCT-derived EC cells to low-dose 5-aza-CdR treatment.
authors: Department of Pharmacology, Dartmouth Medical School, Hanover, New Hamsphire 03755, USA.
authors: Maroun J
authors: MJ
authors: Beyrouthy
authors: Kristen M
authors: KM
authors: Garner
authors: Mary P
authors: MP
authors: Hever
authors: Sarah J
authors: SJ
authors: Freemantle
authors: Alan
authors: A
authors: Eastman
authors: Ethan
authors: E
authors: Dmitrovsky
authors: Michael J
authors: MJ
authors: Spinella
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D001374:Azacitidine / Q000031:analogs & derivatives* / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000378:metabolism; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000096:biosynthesis* / Q000235:genetics; D019175:DNA Methylation / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000378:metabolism; D000077209:Decitabine; D004305:Dose-Response Relationship, Drug; D016147:Genes, Tumor Suppressor; D006657:Histones / Q000378:metabolism; D006801:Humans; D008297:Male; D009373:Neoplasms, Germ Cell and Embryonal / Q000188:drug therapy* / Q000201:enzymology* / Q000235:genetics; D010766:Phosphorylation / Q000187:drug effects; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D013736:Testicular Neoplasms / Q000188:drug therapy* / Q000201:enzymology* / Q000235:genetics; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D000097584:DNA Methyltransferase 3B
chemical_list: D064007:Ataxia Telangiectasia Mutated Proteins; D001374:Azacitidine; D018797:Cell Cycle Proteins; D002945:Cisplatin; D004248:DNA (Cytosine-5-)-Methyltransferases; D004268:DNA-Binding Proteins; D000077209:Decitabine; D006657:Histones; D017346:Protein Serine-Threonine Kinases; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; D000097584:DNA Methyltransferase 3B; C468783:H2AX protein, human; C576324:ATM protein, human