Noyan Senem, Gür Dedeoğlu Bala
Biotechnology Institute, Ankara University, Ankara, Turkiye.
Turk J Biol. 2024 Feb 5;48(2):153-162. doi: 10.55730/1300-0152.2690. eCollection 2024.
BACKGROUND/AIM: Studies highlighted the bidirectional crosstalk between the HER family members in breast cancer as resistance mechanism to anti-HER agents. Cross-signaling between HER2/EGFR and ER/IGF1R could play role in the development of resistance to therapeutics hence stimulating cell growth. To overcome this resistance, combined therapies targeting both pathways simultaneously have been proposed as an effective strategy. The involvement of miRNAs in resistance of targeted therapies like trastuzumab was demonstrated in recent studies. Hence the regulation of miRNAs in resistance state could reverse the cell behaviour to drugs. Previously we found that overexpression of miR-770-5p downregulated AKT and ERK expression through HER2 signaling and potentiated the effect of trastuzumab. In this study we examined the impact of miR-770-5p on trastuzumab resistance.
Cells were treated with tamoxifen or trastuzumab to examine their role in bidirectional crosstalk. The molecule mechanism of miR-770-5p on HER2/EGFR/IGF1R bidirectional crosstalk was explored by western blot. The expression of miR-770-5p in trastuzumab resistant cells was examined by q-PCR. To investigate the effect of miR-770-5p on cancer cell proliferation in trastuzumab resistance state, resistant cells were analyzed by iCELLigence real-time cell analyzer.
miR-770-5p expression was significantly downregulated in trastuzumab-resistant BT-474 and SK-BR-3 cells. Overexpression of miR-770-5p sensitized the resistant cells to trastuzumab, as evidenced by reduced cell proliferation and increased cell viability. Additionally, in resistant cells, increased expression and activation of EGFR and IGF1R were observed. However, miR-770-5p overexpression resulted in decreased phosphorylation of AKT and ERK, indicating its suppressive role in EGFR/HER2 signaling. Furthermore, miR-770-5p downregulated the expression of IGF1R and mTOR, suggesting its involvement in regulating the escape signaling mediated by IGF1R in resistance.
In conclusion, our findings demonstrate the critical role of miR-770-5p in regulating bidirectional crosstalk and overcoming trastuzumab resistance in breast cancer cells. These results highlight the potential of miR-770-5p as a therapeutic target to improve the efficacy of targeted therapies and address resistance mechanisms in breast cancer.
背景/目的：研究强调了乳腺癌中HER家族成员之间的双向串扰是对抗HER药物的耐药机制。HER2/EGFR与ER/IGF1R之间的交叉信号传导可能在治疗耐药性的发展中起作用，从而刺激细胞生长。为克服这种耐药性，已提出同时靶向这两条途径的联合疗法作为一种有效策略。最近的研究证明了miRNA在曲妥珠单抗等靶向治疗耐药性中的作用。因此，在耐药状态下对miRNA的调控可能会逆转细胞对药物的反应。此前我们发现miR-770-5p的过表达通过HER2信号通路下调AKT和ERK的表达，并增强了曲妥珠单抗的作用。在本研究中，我们检测了miR-770-5p对曲妥珠单抗耐药性的影响。
用他莫昔芬或曲妥珠单抗处理细胞，以研究它们在双向串扰中的作用。通过蛋白质印迹法探究miR-770-5p对HER2/EGFR/IGF1R双向串扰的分子机制。通过q-PCR检测曲妥珠单抗耐药细胞中miR-770-5p的表达。为研究miR-770-5p对曲妥珠单抗耐药状态下癌细胞增殖的影响，使用实时无标记细胞功能分析仪对耐药细胞进行分析。
在曲妥珠单抗耐药的BT-474和SK-BR-3细胞中，miR-770-5p的表达显著下调。miR-770-5p的过表达使耐药细胞对曲妥珠单抗敏感，表现为细胞增殖减少和细胞活力增加。此外，在耐药细胞中，观察到EGFR和IGF1R的表达及激活增加。然而，miR-770-5p的过表达导致AKT和ERK的磷酸化减少，表明其在EGFR/HER2信号传导中起抑制作用。此外，miR-770-5p下调了IGF1R和mTOR的表达，表明其参与调节耐药中由IGF1R介导的逃逸信号。
总之，我们的研究结果证明了miR-770-5p在调节双向串扰和克服乳腺癌细胞曲妥珠单抗耐药性中的关键作用。这些结果突出了miR-770-5p作为治疗靶点的潜力，以提高靶向治疗的疗效并解决乳腺癌的耐药机制。
