PDF(Pubmed)
Abstract：
OBJECTIVE: BRCA1/2 mutations in breast cancer cells impair homologous recombination and promote alternative end joining (Alt-EJ) for DNA-damage repair. DNA polymerase theta, encoded by POLQ, plays a crucial role in Alt-EJ, making it a potential therapeutic target, particularly in BRCA1/2-mutant cancers. Methionine restriction is a promising approach to target cancer cells due to their addiction to this amino acid. The present study investigated the expression of POLQ in BRCA1/2 wild-type and BRCA1-mutant breast cancer cells under methionine restriction.
METHODS: POLQ mRNA expression was measured using qRT-PCR in BRCA1/2 wild-type (MDA-MB-231) and BRCA1- mutant (HCC1937 and MDA-MB-436) breast-cancer cells under normal, or serum-restricted, or serum- and methionine-restricted conditions.
RESULTS: Compared to BRCA1/2 wild-type cells, BRCA1-mutant cells displayed significantly higher basal POLQ expression in normal medium. Methionine restriction further increased POLQ expression in the BRCA1-mutant cells but decreased it in the BRCA1/2 wild-type cells.
CONCLUSIONS: The present findings suggest that methionine restriction showed differential effects on POLQ expression, potentially impacting Alt-EJ activity, in BRCA1/2 wild-type and BRCA1-mutant breast-cancer cells. Further investigation is needed to explore the potential of combining methionine restriction with DNA-repair inhibitors, such as PARP inhibitors, to overcome drug resistance in BRCA1/2 mutant cancers.
METHODS: POLQ mRNA expression was measured using qRT-PCR in BRCA1/2 wild-type (MDA-MB-231) and BRCA1- mutant (HCC1937 and MDA-MB-436) breast-cancer cells under normal, or serum-restricted, or serum- and methionine-restricted conditions.
RESULTS: Compared to BRCA1/2 wild-type cells, BRCA1-mutant cells displayed significantly higher basal POLQ expression in normal medium. Methionine restriction further increased POLQ expression in the BRCA1-mutant cells but decreased it in the BRCA1/2 wild-type cells.
CONCLUSIONS: The present findings suggest that methionine restriction showed differential effects on POLQ expression, potentially impacting Alt-EJ activity, in BRCA1/2 wild-type and BRCA1-mutant breast-cancer cells. Further investigation is needed to explore the potential of combining methionine restriction with DNA-repair inhibitors, such as PARP inhibitors, to overcome drug resistance in BRCA1/2 mutant cancers.
摘要：
目的：乳腺癌细胞中的BRCA1/2突变损害同源重组并促进DNA损伤修复的替代末端连接（Alt-EJ）。DNA聚合酶θ,由POLQ编码，在Alt-EJ中起着至关重要的作用，使其成为潜在的治疗靶点，特别是在BRCA1/2突变癌症中。蛋氨酸限制是靶向癌细胞的一种有前途的方法，因为它们对这种氨基酸成瘾。本研究在蛋氨酸限制下研究了BRCA1/2野生型和BRCA1突变型乳腺癌细胞中POLQ的表达。
方法：使用qRT-PCR在BRCA1/2野生型（MDA-MB-231）和BRCA1-突变型（HCC1937和MDA-MB-436）乳腺癌细胞中测量POLQmRNA的表达。或血清限制，或血清和蛋氨酸限制条件。
结果：与BRCA1/2野生型细胞相比，BRCA1突变细胞在正常培养基中表现出明显更高的基础POLQ表达。甲硫氨酸限制进一步增加了BRCA1突变细胞中的POLQ表达，但降低了BRCA1/2野生型细胞中的POLQ表达。
结论：目前的研究结果表明，蛋氨酸限制对POLQ表达有不同的影响，可能影响Alt-EJ活动,在BRCA1/2野生型和BRCA1突变型乳腺癌细胞中。需要进一步的研究来探索结合甲硫氨酸限制和DNA修复抑制剂的潜力，如PARP抑制剂，克服BRCA1/2突变癌症的耐药性。
方法：使用qRT-PCR在BRCA1/2野生型（MDA-MB-231）和BRCA1-突变型（HCC1937和MDA-MB-436）乳腺癌细胞中测量POLQmRNA的表达。或血清限制，或血清和蛋氨酸限制条件。
结果：与BRCA1/2野生型细胞相比，BRCA1突变细胞在正常培养基中表现出明显更高的基础POLQ表达。甲硫氨酸限制进一步增加了BRCA1突变细胞中的POLQ表达，但降低了BRCA1/2野生型细胞中的POLQ表达。
结论：目前的研究结果表明，蛋氨酸限制对POLQ表达有不同的影响，可能影响Alt-EJ活动,在BRCA1/2野生型和BRCA1突变型乳腺癌细胞中。需要进一步的研究来探索结合甲硫氨酸限制和DNA修复抑制剂的潜力，如PARP抑制剂，克服BRCA1/2突变癌症的耐药性。
