Preclinical approach of two novel tetrahydroquinoline derivatives targeting GPER and Bcl-2 for anti-glioblastoma therapy

Glioblastoma multiforme (GBM), is a rapidly growing and aggressive brain tumor that can arise de novo in the brain or evolve from lower-grade astrocytoma. This malignancy represents a medical challenge due to the tumor´s localization in the brain, high rates of Temozolomide (TMZ) resistance, and extensive malignant cell parenchymal infiltration, among Other factors. Consequently, new drug discovery efforts have focused on targeting pivotal pharmacological targets such as GPER and Bcl-2, presenting a promising strategy for developing new GBM treatments. Herein, we present the results of an improved structure guided design of anti-glioblastoma compounds, L-06 and L-37, both containing the tetrahydroquinoline scaffold and a sulfonamide moiety recognized by GPER and Bcl-2 binding sites, respectively. Both compounds were evaluated in a battery of in vitro assays to measure their anti-glioblastoma activity. L-06 and L-37 were subjected to chemical stability testing under forced degradation conditions indicated minimal degradation from 0.15 to 13.6%. Additionally, antiproliferative evaluation in 2D Cell Culture yielded IC₅₀ values between 39 and 67 µM in GBM cell lines LN18 and U373, consistent with Gossypol, a well-known Bcl-2 Inhibitor. G-15 and L-37 to a greater extent than L-06, inhibit neurospheres formation in glioblastoma stem cells (Gli4) cultured in a proliferation medium. Moreover, in 3D antiproliferative assays using glioblastoma stem cells on non-aligned nanofibers L-37 showed better inhibitory effect than L-06. Interestingly, L-06 than L-37 exhibited an antimigratory effect on glioblastoma stem cells loaded onto aligned nanofibers at concentrations where no antiproliferative activity were observed, unlike G-15, a poorly water soluble GPER antagonist. Collectively, these findings establish a preclinical foundation for L-37 and L-06 as potential anti-glioblastoma agents and support their further investigation as therapeutic candidates.