PTIP Inhibits Cell Invasion in Esophageal Squamous Cell Carcinoma via Modulation of EphA2 Expression

MiR-302a-3p reduces cisplatin resistance of esophageal squamous cell carcinoma cells by targeting EphA2

Platinum-based chemotherapy is a common clinical treatment for esophageal squamous cell carcinoma (ESCC), and chemoresistance is a major leading reason for cancer treatment failure. MiR-302a-3p is involved in the development of many diseases. Here, we investigated the role of miR-302a-3p in the cisplatin resistance of ESCC cells and explored its potential mechanism via molecular techniques. The expression of miR-302a-3p was significantly reduced, while the expressions of EphA2 were increased in ESCC tumor tissues and cells. EphA2 was one target gene of miR-302a-3p, and was negatively regulated by miR-302a-3p. By regulating EphA2, miR-302a-3p reduced the viability and promoted the apoptosis of ECA109 cells treated with cisplatin, suggesting that miR-302a-3p could enhance the sensitivity of ECA109 cells to cisplatin treatment by targeting EphA2. MiR-302a-3p plays an important role in reducing cisplatin resistance by inhibiting EphA2, suggesting that it may be a promising therapeutic strategy for cisplatin resistance in ESCC in the future.

The genomic stability regulator PTIP is required for proper chromosome segregation in mitosis

Background

The Pax transcription activation domain-interacting protein (PTIP) is a nuclear protein that is an essential component of H3K4 methylation for gene activation in vascular, kidney, B cell, and adipocyte development. Furthermore, it plays a key role in genomic stability in higher eukaryotic cells. It binds to 53BP1 and antagonizes inappropriate homologous recombination for a proper DNA damage response. Interestingly, an early study reported mitotic defects after PTIP inactivation, but it is not clear whether PTIP directly facilitates mitotic processes.

Results

Here, we showed that PTIP is essential for the mitotic integrity of HeLa cells. PTIP inactivation increases cell death during mitotic exit, which appears to result from direct mitotic defects. PTIP inactivation did not affect the G2M DNA damage checkpoint during interphase upon etoposide treatment. However, in mitosis, PTIP inactivation results in prolonged mitotic time, inefficient chromosome alignment, and increased cell death. Furthermore, PTIP localizes to the mitotic centrosome via BRCT domains at the C-terminus.

Conclusion

This study reveals a novel function of PTIP in maintaining the genomic stability of higher eukaryotes during mitosis. Therefore, its deregulation, which occurs in various tumors, may destabilize the genome by introducing an abnormal DNA damage response, as well as erroneous chromosome segregation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13008-022-00081-4.