Introduction:Hydroxysteroid 17-beta dehydrogenase 4 (HSD17B4) is involved in the
progression of hepatocellular carcinoma (HCC).Aims:This study aimed to investigate the inhibitory effect of gamma-tocotrienol (γ-T3) on the proliferation
and growth of HSD17B4-overexpressing HepG2 cells.Methods:HepG2 cells were transfected with empty or HSD17B4-overexpressing plasmids, followed
by vitamin E (VE) or γ-T3 treatment. MTS assay, Western blotting, qRT-PCR, and flow cytometry
were employed to assess cell proliferation, protein expression, mRNA levels, and apoptosis.
HSD17B4 interaction with γ-T3 was assessed by quantifying γ-T3 in the collected precipitate
of HSD17B4 using anti-flag magnetic beads. Tumor xenografts were established in NSG mice,
and tumor growth was monitored.Results:HSD17B4 overexpression significantly promoted HepG2 cell proliferation, which was effectively
counteracted by VE or γ-T3 treatment in a dose-dependent manner. VE and γ-T3 did not
exert their effects through direct regulation of HSD17B4 expression. Instead, γ-T3 was found to interact
with HSD17B4, inhibiting its activity in catalyzing the conversion of estradiol (E2) into estrone.
Moreover, γ-T3 treatment led to a reduction in cyclin D1 expression and suppressed key proliferation
signaling pathways, such as ERK, MEK, AKT, and STAT3. Additionally, γ-T3 promoted
apoptosis in HSD17B4-overexpressing HepG2 cells. In an in vivo model, γ-T3 effectively reduced
the growth of HepG2 xenograft tumors.Conclusion:In conclusion, our study demonstrates that γ-T3 exhibits potent anti-proliferative and
anti-tumor effects against HepG2 cells overexpressing HSD17B4. These findings highlight the
therapeutic potential of γ-T3 in HCC treatment and suggest its role in targeting HSD17B4-associated
pathways to inhibit tumor growth and enhance apoptosis.