Gossypol acetic acid regulates leukemia stem cells by degrading LRPPRC via inhibiting IL-6/JAK1/STAT3 signaling or resulting mitochondrial dysfunction

BACKGROUND Leukemia stem cells(LSCs)are found to be one of the main factors contributing to poor therapeutic effects in acute myeloid leukemia(AML),as they are protected by the bone marrow microenvironment(BMM)against conventional therapies.Gossypol acetic acid(GAA),which is extracted from the seeds of cotton plants,exerts anti-tumor roles in several types of cancer and has been reported to induce apoptosis of LSCs by inhibiting Bcl2.AIM To investigate the exact roles of GAA in regulating LSCs under different microenvironments and the exact mechanism.METHODS In this study,LSCs were magnetically sorted from AML cell lines and the CD34+CD38-population was obtained.The expression of leucine-rich pentatricopeptide repeat-containing protein(LRPPRC)and forkhead box M1(FOXM1)was evaluated in LSCs,and the effects of GAA on malignancies and mitochondrial RESULTS LRPPRC was found to be upregulated,and GAA inhibited cell proliferation by degrading LRPPRC.GAA induced LRPPRC degradation and inhibited the activation of interleukin 6(IL-6)/janus kinase(JAK)1/signal transducer and activator of transcription(STAT)3 signaling,enhancing chemosensitivity in LSCs against conventional chemotherapies,including L-Asparaginase,Dexamethasone,and cytarabine.GAA was also found to downregulate FOXM1 indirectly by regulating LRPPRC.Furthermore,GAA induced reactive oxygen species accumulation,disturbed mitochondrial homeostasis,and caused mitochondrial dysfunction.By inhibiting IL-6/JAK1/STAT3 signaling via degrading LRPPRC,GAA resulted in the elimination of LSCs.Meanwhile,GAA induced oxidative stress and subsequent cell damage by causing mitochondrial damage.CONCLUSION Taken together,the results indicate that GAA might overcome the BMM protective effect and be considered as a novel and effective combination therapy for AML.

The Effect of Gossypol and Misoprostol on Luteal and Decidual Cells in Vitro

Gossypol and Misoprostol could directly damage the luteal and decidual cells cultured in vitro. The LD50 of gossypol alone to luteal and decidual cells were 1.27±0.09 μg/ml and 3.06±0.23 μg/ml, respectively; however when combined with misoprostol (to luteal cells 5μg/ml, or to decidual cells 10μg/ml), the LD50 of gossypol signifcantly decreased to 0.89±0.25 μg/ml and 1.88±0.26 μg/ml, respectively. The LD50 of misoprostol alone to luteal and decidual cells were 14.29±1.29μg/ml and 24.37±4.49 μg/ml, respectively; but it decreased to 8.79±2.18 μg/mland 17.29±1.56 μg/ml, respectively when combined with gossypol (to luteal cells 0.5 μg/ml, or to decidual cells 1.0 μg/ml), also showing statistical difference. The results suggested that the combination of gossypol with misoprostol had synergistic effect on the degeneration of luteal and decidual cells in vitro.

Co-administration of Mixed Steroid Hormones can Enhance the Recovery of Spermatogenesis Damaged by Gossypol Acetic Acid in Adult Rats

Objective To determine whether co-administration of mixed steriod hormones can enhance the restoration of spermatogenesis damaged by gossypol acetic acid （GA）. Methods Adult male Wistar rats were treated daily for 8 weeks with GA at 50mg/kg plus testosterone undercanoate （100 mg/kg）/desogestrel （0.125 mg/kg）/mini-dose ethinylestradiol （0.025 mg/kg） （TU/DSG/EE）, followed by a period of 9 weeks for recovery. Control animals were administered the same dose of GA or TU/DSG/EE, and vehicle, respectively. Testis weight, testicular sperm head count and histological analysis were utilized to assess the spermatogenesis. Results At the end of the 9-week reovery period, in rats given GA alone, spermato- genesis steadily declined. However, when rats received combined hormone adminis- tration during GA treatment, this decline was prevented and an complete recovery of spermagenesis occurred. The haploid spermatids and spermatocytes was not to be protected but to be more aggravatedly damaged. The excellent recovery must have resulted from that the hormone treatment could protect the ability of stem spermatogonia to differentialte and evolve progressively into mature spermatozoa. In addition, the concentrations of serum LH, FSH and intratesticular testosteron （ITT） notably decreased after 2 or 8 weeks of treatment, then returned to control levels at the end of 9-week recovery period.Conclusion Steriod hormone treatment enhaces the recovery of spermatogenesis through preventing seminiferous epithelim from GA-induced destructive damage in rats. The enhanced recovery was closely associated with the marked suppression in intratesticular testosteron （ITT）.