An integrated in vitro/in silico approach to assess the anti-androgenic potency of isobavachin.

Isobavachin is a dietary flavanone with multiple biological activities. Our previous research has confirmed the estrogenicity of isobavachin, and this work aims to assess the anti-androgenic potency of isobavachin by an integrated in vitro and in silico approach. Isobavachin can limit the proliferation of prostate cancer cells by inducing a distinct G1 cell-cycle arrest. In addition, isobavachin also significantly represses the transcription of androgen receptor (AR)-downstream targets such as prostate specific antigen. Mechanistically, we demonstrated that isobavachin can disrupt the nuclear translocation of AR and promote its proteasomal degradation. The results of computer simulations showed that isobavachin can stably bind to AR, and the amino acid residue Gln711 may play a critical role in AR binding of both AR agonists and antagonists. In conclusion, this work has identified isobavachin as a novel AR antagonist.

Androgen receptor splicing variant 7 (ARv7) promotes DNA damage response in prostate cancer cells.

In the treatment of patients with locally advanced prostate cancer (PCa), androgen deprivation therapy (ADT) significantly enhances the efficacy of radiotherapy by weakening the DNA damage response (DDR) pathway. Recently, several studies have suggested that androgen receptor splicing variants (ARvs) may mediate a compensatory DDR pathway when canonical androgen receptor (AR) signaling is inhibited, thus contributing to the resistance of some patients to this combinational treatment. However, the specific roles of certain ARvs as well as the detailed mechanism of how ARvs regulate the DDR are not well understood. Here, we demonstrated that AR splicing variant 7 (ARv7), which is the most abundant form of ARvs, significantly promotes the DDR of PCa cells under severe DNA damage independent of its parental AR by using the ionizing radiation (IR) and doxorubicin (Dox)-treated cell models. Mechanistically, ARv7 is sufficient to upregulate both the homologous recombination (HR) and the nonhomologous end joining (NHEJ) pathways by forming a positive regulatory loop with poly ADP-ribose polymerase 1 (PARP1). Moreover, the presence of ARv7 impairs the synergistic effect between AR antagonists and poly ADP-ribose polymerase (PARP) inhibitor, which has been recently shown to be a promising future treatment strategy for metastatic castration resistant prostate cancer (mCRPC). Combined, our data indicate that constitutively active ARv7 not only contributes to radioresistance after ADT, but may also serve as a potential predictive biomarker for assessing the efficacy of novel PARP inhibitor-based therapy in PCa.

Progress of HOTAIR-microRNA in hepatocellular carcinoma.

The Hox transcript antisense intergenic RNA (HOTAIR) has been identified as a tumor gene, and its expression in HCC is significantly increased. HOTAIR is associated with the proliferation, invasion, metastasis and poor prognosis of HCC. In addition, HOTAIR can also regulate the expression and function of microRNA by recruiting the polycomb repressive complex 2 (PRC2) and competitive adsorption, thus promoting the occurrence and development of HCC. In this review, we discussed the two mechanisms of HOTAIR regulating miRNA through direct binding miRNA and indirect regulation, and emphasized the role of HOTAIR in HCC through miRNA, explained the regulatory pathway of HOTAIR-miRNA-mRNA and introduced the role of this pathway in HCC proliferation, drug resistance, invasion and metastasis.

PGC1α Promotes Cisplatin Resistance in Ovarian Cancer by Regulating the HSP70/HK2/VDAC1 Signaling Pathway.

Mitochondrial apoptosis is one of the main mechanisms for cancer cells to overcome chemoresistance. Hexokinase 2 (HK2) can resist cancer cell apoptosis by expressing on mitochondria and binding to voltage-dependent anion channel 1 (VDAC1). We previously reported that peroxisome proliferator-activated receptor coactivator 1 α (PGC1α) is highly expressed in ovarian cancer cisplatin-resistant cells. However, the underlying mechanism remains unclear. Therefore, we evaluated the interaction between PGC1α and HK2 in ovarian cancer cisplatin-resistant cells. We found that the knockdown of PGC1α promotes the apoptosis of ovarian cancer cisplatin-resistant cells and increases their sensitivity to cisplatin. In addition, we found that the knockdown of PGC1α affects the mitochondrial membrane potential and the binding of HK2 and VDAC1. As the heat shock protein 70 (HSP70) family can help protein transport, we detected it and found that PGC1α can promote HSP70 gene transcription. Furthermore, HSP70 can promote an increase of HK2 expression on mitochondria and an increase of binding to VDAC1. Based on these results, PGC1α may reduce apoptosis through the HSP70/HK2/VDAC1 signaling pathway, thus promoting cisplatin resistance of ovarian cancer. These findings provide strong theoretical support for PGC1α as a potential therapeutic target of cisplatin resistance in ovarian cancer.

Mitochondrial integration and ovarian cancer chemotherapy resistance.

Ovarian cancer has been nicknamed the "silent killer". Most patients with ovarian cancer are diagnosed at an advanced stage of the disease for the first time because of its insignificant early clinical symptoms. In addition to the difficulty of early screening and delay in diagnosis, the high recurrence rate and relapsed refractory status of patients with ovarian cancer are also important factors for their high mortality. Patients with recurrent ovarian cancer often use neoadjuvant chemotherapy followed by surgery as the first choice. However, this is often accompanied by chemotherapy resistance, leading to treatment failure and a mortality rate of more than 90%. In the past, it was believed that the anti-tumor effect of chemotherapeutics represented by cisplatin was entirely attributable to its irreversible damage to DNA, but current research has found that it can inhibit cell growth and cytotoxicity via nuclear and cytoplasmic coordinated integration. As an important hub and integration platform for intracellular signal communication, mitochondria are responsible for multiple key factors during tumor occurrence and development, such as metabolic reprogramming, acquisition of metastatic ability, and chemotherapy drug response. The role of mitochondria in ovarian cancer chemotherapy resistance is becoming increasingly recognized. In this review, we discuss the cellular interactive regulatory network surrounding mitochondria, elucidate the mechanisms of tumor cell survival under chemotherapy, and discuss potential means of interfering with mitochondrial function as a novel anti-cancer therapy.

Androgen receptor splicing variant 7 (ARV7) inhibits docetaxel sensitivity by inactivating the spindle assembly checkpoint.

The clinical efficacy of docetaxel (DTX) in prostate cancer treatment is barely satisfactory due to diverse responses of the patients, including the development of resistance. Recently, aberrant androgen receptor (AR) signaling, including expression of the constitutively active ARV7, was reported to contribute to DTX resistance. However, the underlying molecular mechanism remains largely unknown. Of note, previous studies have highlighted that ARV7, unlike its parental AR, potentially favors the expression of some genes involved in cell cycle progression. Since DTX mainly targets microtubule dynamics and mitosis, we wanted to test whether ARV7 plays a specific role in mitotic regulation and whether this activity is involved in DTX resistance. In the present study, we found that ARV7 mediates DTX sensitivity through inactivating the spindle assembly checkpoint (SAC) and promoting mitotic slippage. By shifting the balance to the slippage pathway, ARV7-expressing cells are more likely to escape from mitotic death induced by acute DTX treatment. Furthermore, we also identified E2 enzyme UBE2C as the primary downstream effector of ARV7 in promoting the SAC inactivation and premature degradation of cyclin B1. Moreover, we showed that combination treatment of DTX and an inhibitor of mitotic exit can exert synergistic effect in high ARV7-expressing prostate cancer cells. In sum, our work identified a novel role of ARV7 in promoting DTX resistance and offering a potential path to combat DTX resistance related to abnormal activation of the AR signaling and mitotic dysregulation.

The Nrf2/PGC1α Pathway Regulates Antioxidant and Proteasomal Activity to Alter Cisplatin Sensitivity in Ovarian Cancer.

Drug resistance remains a barrier in the clinical treatment of ovarian cancer. Proteasomal and antioxidant activities play important roles in tumor drug resistance, and increasing evidence suggests the existence of an interaction between antioxidant and proteasomal activities. However, the mechanism of the synergistic effects of proteasomal activity and antioxidation on tumor drug resistance is not completely clear. In this study, we compared two ovarian cancer cells, A2780 and SKOV3 cells. Among them, SKOV3 cell is a human clear cell carcinoma cell line that is resistant to platinum. We found that compared with the findings in A2780 cells, SKOV3 cells were less sensitive to both proteasomal inhibitor and cisplatin. Proteasomal inhibition enhanced the sensitivity of A2780 cells, but not SKOV3 cells, to cisplatin. Notably, the Nrf2-mediated antioxidant pathway was identified as a resistance mechanism in proteasome inhibitor-resistant cells, but this was not the only factor identified in our research. In SKOV3 cells, PGC1α regulated the antioxidant activity of Nrf2 by increasing the phosphorylation of GSK3ß, and in turn, Nrf2 regulated the transcriptional activity of PGC1α. Thus, Nrf2 and PGC1α synergistically participate in the regulation of proteasomal activity. Furthermore, the Nrf2/PGC1α pathway participated in the regulation of mitochondrial function and homeostasis, further regulating proteasomal activity in SKOV3 cells. Therefore, exploring the roles of PGC1α and Nrf2 in the regulation of proteasomal activity by antioxidant and mitochondrial functions may provide new avenues for reversing drug resistance in ovarian cancer.

Prognostic Significance and Related Mechanisms of Hexokinase 1 in Ovarian Cancer.

PURPOSE: Ovarian cancer (OC) has the highest mortality among gynecological malignancies. Therefore, it is urgent to explore prognostic biomarkers to improve the survival of OC patients. One of the most prominent metabolic characteristics of cancer is effective glycolysis. Hexokinase 1 (HK1), as the first rate-limiting enzyme in glycolysis, is closely related to cancer progression. However, the role of HK1 in OC remains unclear. MATERIALS AND METHODS: The Cancer Genome Atlas (TCGA) database was used to detect the expression of HK1 in OC patients. The chi-squared test was performed to examine the correlations between HK1 and patients' clinical characteristics. Survival analyses were undertaken to determine the relationship between HK1 and patient survival, while the univariate/multivariate Cox model was used to evaluate the role of HK1 in patient prognosis. Gene Set Enrichment Analysis (GSEA) was performed to ascertain the related signaling pathways of HK1. RT-qPCR was implemented to validate the mRNA expression of HK1 in OC cells. MTT was used to detect cell viability after adding 2DG and knocking down HK1 in OC cells. HK1 protein expression was examined by Western blotting. Glucose uptake, lactate production, and ATP assays were undertaken following knockdown of HK1 in OC cells. Colony formation assays were performed to determine OC cell proliferation after HK1 knockdown. Transwell and wound healing assays were carried out to detect the invasion and migration of OC cells after HK1 knockdown. RESULTS: We found that HK1 expression was increased in OC tissues and cells, and HK1 was related to the clinical characteristics of OC patients. Survival analysis revealed that OC patients in the HK1 overexpression group had poor survival. Moreover, univariant/multivariate analyses showed that HK1 may be an independent biomarker for the poor prognosis of OC patients. OC cell viability and proliferation decreased after knockdown of HK1. Consistently, glucose uptake, lactic acid production, ATP production, invasion, and migration were also decreased. Finally, GSEA enrichment analysis and Western blotting showed that HK1 was involved in MAPK/ERK signaling. CONCLUSION: HK1 may be a biomarker for the poor prognosis of OC patients and a potential therapeutic target.