PTEN inhibition leads to the development of resistance to novel isoquinoline derivative TNBG-5602 in human liver cancer cells.

TNBG-5602, a new synthesized derivative of tetrazanbigen, is a potential chemotherapeutic agent against cancer. However, its underlying mechanism is complex and still unknown. In this investigation, the anticancer effects of TNBG-5602 were determined in vitro and in vivo. Small RNA retroviral library plasmids that overexpress 19-bp fragments were used to generate TNBG-5602-resistant cells. After validation, the overexpressed 19-bp fragments were sequenced using next-generation sequencing (NGS) in the drug-resistant cells. Furthermore, the relationship of TNBG-5602, phosphatase and tensin homolog deleted on Chromosome 10 (PTEN), and the phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt) pathway was explored. The results showed that TNBG-5602 can effectively inhibit cancer cell proliferation and induce apoptosis in vitro and in vivo. Drug-resistant cells were screened using the small RNA library. Compared with naive cells, drug-resistant cells were more resistant to TNBG-5602 in vitro and in vivo. NGS results revealed that the second highest overexpressed 19-bp fragment perfectly matched the PTEN gene, so the expression of PTEN in various cells and tissues was verified. Further research showed that exogenous overexpression of PTEN strengthened the anticancer effects of TNBG-5602 on p-Akt expression, whereas silencing of PTEN weakened these effects in naive cells. Taken together, by using this library, we confirmed that PTEN is the target gene to the anticancer effects of TNBG-5602 via the PI3K/Akt pathway.