Histone deacetylase inhibitor reverses multidrug resistance by attenuating the nucleophosmin level through PI3K/Akt pathway in breast cancer

Hormonal and Genetic Regulatory Events in Breast Cancer and Its Therapeutics: Importance of the Steroidogenic Acute Regulatory Protein

Estrogen promotes the development and survival of the majority of breast cancers (BCs). Aromatase is the rate-limiting enzyme in estrogen biosynthesis, and it is immensely expressed in both cancerous and non-cancerous breast tissues. Endocrine therapy based on estrogen blockade, by aromatase inhibitors, has been the mainstay of BC treatment in post-menopausal women; however, resistance to hormone therapy is the leading cause of cancer death. An improved understanding of the molecular underpinnings is the key to develop therapeutic strategies for countering the most prevalent hormone receptor positive BCs. Of note, cholesterol is the precursor of all steroid hormones that are synthesized in a variety of tissues and play crucial roles in diverse processes, ranging from organogenesis to homeostasis to carcinogenesis. The rate-limiting step in steroid biosynthesis is the transport of cholesterol from the outer to the inner mitochondrial membrane, a process that is primarily mediated by the steroidogenic acute regulatory (StAR) protein. Advances in genomic and proteomic technologies have revealed a dynamic link between histone deacetylases (HDACs) and StAR, aromatase, and estrogen regulation. We were the first to report that StAR is abundantly expressed, along with large amounts of 17β-estradiol (E2), in hormone-dependent, but not hormone-independent, BCs, in which StAR was also identified as a novel acetylated protein. Our in-silico analyses of The Cancer Genome Atlas (TCGA) datasets, for StAR and steroidogenic enzyme genes, revealed an inverse correlation between the amplification of the StAR gene and the poor survival of BC patients. Additionally, we reported that a number of HDAC inhibitors, by altering StAR acetylation patterns, repress E2 synthesis in hormone-sensitive BC cells. This review highlights the current understanding of molecular pathogenesis of BCs, especially for luminal subtypes, and their therapeutics, underlining that StAR could serve not only as a prognostic marker, but also as a therapeutic candidate, in the prevention and treatment of this life-threatening disease.

Valproic Acid and Breast Cancer: State of the Art in 2021

Valproic acid (2-propylpentanoic acid, VPA) is a short-chain fatty acid, a member of the group of histone deacetylase inhibitors (HDIs). VPA has been successfully used in the treatment of epilepsy, bipolar disorders, and schizophrenia for over 50 years. Numerous in vitro and in vivo pre-clinical studies suggest that this well-known anticonvulsant drug significantly inhibits cancer cell proliferation by modulating multiple signaling pathways. Breast cancer (BC) is the most common malignancy affecting women worldwide. Despite significant progress in the treatment of BC, serious adverse effects, high toxicity to normal cells, and the occurrence of multi-drug resistance (MDR) still limit the effective therapy of BC patients. Thus, new agents which improve the effectiveness of currently used methods, decrease the emergence of MDR, and increase disease-free survival are highly needed. This review focuses on in vitro and in vivo experimental data on VPA, applied individually or in combination with other anti-cancer agents, in the treatment of different histological subtypes of BC.

The multidrug resistance can be reversed for the decrease of P-gp and LRP by inhibiting PI3K/Akt/NF-κB signal pathway in nasopharynx carcinoma

AIM

To investigate the relationship between PI3K/Akt/NF-κB cellular signal pathway and the expression of P-gp and LRP in multidrug resistance (MDR) cell of nasopharyngeal carcinoma.

METHOD

The PI3K, p-Akt and NF-κB/p65 as the activity of PI3K/Akt/NF-κB were detected by Western blot. The expressions of LRP and P-gp were detected by Western blot and real-time PCR.

RESULT

The RIs of CNE/DDP group to DDP, 5-Fu, VCR, ADR and PTX were 35.04, 18.14, 24.13, 12.00 and 10.18, respectively. The RIs of LY-294002 group were 11.77, 5.83, 3.07, 3.86 and 3.34, and PDTC group were 11.08, 6.55, 7.66, 2.18 and 4.05. The expressions of PI3K, p-Akt and NF-κBp65, LRP and P-gp were increased and mRNA of LRP and P-gp were up-regulated in CNE/DDP. The expression of p-Akt in LY-294002 group was down-regulated. The expression of NF-κB p65 in PDTC group was decreased. The mRNA of LRP and P-gp in LY-294002 group and PDTC group were decreased.

CONCLUSION

MDR of nasopharyngeal carcinoma cell can be regulated by activating PI3K/Akt/NF-κB signal pathway and then increase the expression of P-gp and LRP. The MDR of nasopharyngeal carcinoma cell can be reversed by inhibiting PI3K/Akt/NF-κB signal pathway.

Chidamide increases the sensitivity of Non-small Cell Lung Cancer to Crizotinib by decreasing c-MET mRNA methylation

Introduction: Crizotinib is a kinase inhibitor targeting c-MET/ALK/ROS1 used as the first-line chemical for the treatment of non-small cell lung cancer (NSCLC) with ALK mutations. Although c-MET is frequently overexpressed in 35-72% of NSCLC, most NSCLCs are primarily resistant to crizotinib treatment.

Method: A set of NSCLC cell lines were used to test the effect of chidamide on the primary crizotinib resistance in vitro and in vivo. Relationships between the synergistic effect of chidamide and c-MET expression and RNA methylation were systemically studied with a battery of molecular biological assays.

Results: We found for the first time that chidamide could sensitize the effect of crizotinib in a set of ALK mutation-free NSCLC cell lines, especially those with high levels of c-MET expression. Notably, chidamide could not increase the sensitivity of NSCLC cells to crizotinib cultured in serum-free medium without hepatocyte growth factor (HGF; a c-MET ligand). In contrast, the addition of HGF into the serum-/HGF-free medium could restore the synergistic effect of chidamide. Moreover, the synergistic effect of chidamide could also be abolished either by treatment with c-MET antibody or siRNA-knockdown of c-MET expression. While cells with low or no c-MET expression were primarily resistant to chidamide-crizotinib cotreatment, enforced c-MET overexpression could increase the sensitivity of these cells to chidamide-crizotinib cotreatment. Furthermore, chidamide could decrease c-MET expression by inhibiting mRNA N6-methyladenosine (m6A) modification through the downregulation of METTL3 and WTAP expression. Chidamide-crizotinib cotreatment significantly suppressed the activity of c-MET downstream molecules.

Conclusion: Chidamide downregulated c-MET expression by decreasing its mRNA m6A methylation, subsequently increasing the crizotinib sensitivity of NSCLC cells in a c-MET-/HGF-dependent manner.

Zinc Dependent Histone Deacetylase Inhibitors in Cancer Therapeutics: Recent Update

BACKGROUND

Histone deacetylases (HDAC) are an important class of enzymes that play a pivotal role in epigenetic regulation of gene expression that modifies the terminal of core histones leading to remodelling of chromatin topology and thereby controlling gene expression. HDAC inhibitors (HDACi) counter this action and can result in hyperacetylation of histones, thereby inducing an array of cellular consequences such as activation of apoptotic pathways, generation of reactive oxygen species (ROS), cell cycle arrest and autophagy. Hence, there is a growing interest in the potential clinical use of HDAC inhibitors as a new class of targeted cancer therapeutics. Methodology and Result: Several research articles spanning between 2016 and 2017 were reviewed in this article and presently offer critical insights into the important strategies such as structure-based rational drug design, multi-parameter lead optimization methodologies, relevant SAR studies and biology of various class of HDAC inhibitors, such as hydroxamic acids, benzamides, cyclic peptides, aliphatic acids, summarising the clinical trials and results of various combination drug therapy till date.

CONCLUSION

This review will provide a platform to the synthetic chemists and biologists to cater the needs of both molecular targeted therapy and combination drug therapy to design and synthesize safe and selective HDAC inhibitors in cancer therapeutics.

Nucleophosmin/B23 contributes to hepatic insulin resistance through the modulation of NF-κB pathway

Nucleophosmin (NPM)/B23 is an important nucleolar phosphoprotein involved in the regulation of assorted cellular signaling pathways. In the present study, we revealed a critical role of NPM in liver insulin resistance. NPM is markedly upregulated in insulin-resistant liver tissues and palmitic acid (PA)-exposed HepG2 cells both at mRNA and protein levels. Ectopic expression of NPM in hepatocytes aggravated PA-induced insulin resistance, lipid droplet accumulation, glucose intake impairment as well as the expression of gluconeogenic genes. Coinciding with these results, interference of NPM using small interfering RNA (siRNA) oligos ameliorated PA-induced insulin resistance, as revealed by increased phosphorylation of AKT and GSK3β following insulin treatment. As predicted, PA-triggered alterations in glucose intake and the expression of gluconeogenic enzymes were attenuated following NPM depletion. Finally, we showed that NPM plays an indispensible role in PA-induced activation of NF-κB pathway. Both of NF-κB p65 phosphorylation and nuclear translocation were impeded by NPM interference in PA-treated HepG2 cells. Taken together, these findings explicitly demonstrate that NPM participates in the development of liver insulin resistance, suggesting that NPM may serve as a potential therapeutic target of type 2 diabetes.

HDAC inhibition as a treatment concept to combat temsirolimus-resistant bladder cancer cells

Introduction

Although the mechanistic target of rapamycin (mTOR) might be a promising molecular target to treat advanced bladder cancer, resistance develops under chronic exposure to an mTOR inhibitor (everolimus, temsirolimus). Based on earlier studies, we proposed that histone deacetylase (HDAC) blockade might circumvent resistance and investigated whether HDAC inhibition has an impact on growth of bladder cancer cells with acquired resistance towards temsirolimus.

Results

The HDAC inhibitor valproic acid (VPA) significantly inhibited growth, proliferation and caused G0/G1 phase arrest in RT112^res and UMUC-3^res. cdk1, cyclin B, cdk2, cyclin A and Skp1 p19 were down-regulated, p27 was elevated. Akt-mTOR signaling was deactivated, whereas acetylation of histone H3 and H4 in RT112^res and UMUC-3^res increased in the presence of VPA. Knocking down cdk2 or cyclin A resulted in a significant growth blockade of RT112^res and UMUC-3^res.

Materials And Methods

Parental (par) and resistant (res) RT112 and UMUC-3 cells were exposed to the HDAC inhibitor VPA. Tumor cell growth, proliferation, cell cycling and expression of cell cycle regulating proteins were then evaluated. siRNA blockade was used to investigate the functional impact of the proteins.

Conclusions

HDAC inhibition induced a strong response of temsirolimus-resistant bladder cancer cells. Therefore, the temsirolimus-VPA-combination might be an innovative strategy for bladder cancer treatment.

Kanglaite inhibits the expression of drug resistance genes through suppressing PVT1 in cisplatin-resistant gastric cancer cells

Kanglaite (KLT) was shown to alleviate the development of multidrug resistance (MDR) clinically. The purpose of this study is to examine the mechanism of KLT for chemotherapy resistance in gastric cancer cells involving the regulation of MDR-related proteins. The cisplatin-resistant BGC823/DPP and SGC7901/DDP cells were treated with 1, 2.5 and 5 µl/ml of KLT for 24, 36 and 48 h. Cell Counting Kit-8 (CCK-8) assay and flow cytometry were performed to detect the cell viability and cell apoptosis, respectively. The expression of MDR1 and multidrug resistance associated protein 1 (MRP1) were examined by quantitative PCR and western blotting in BGC823/DPP cells and SGC7901/DDP cells treated with KLT. The effect of KLT on the expression of PVT1 was investigated. PVT1-overexpression vector was constructed and transfected into BGC823/DPP cells and SGC7901/DDP cells which were treated with KLT. KLT inhibited the cell viability and promoted the cell apoptosis of BGC823/DPP cells and SGC7901/DDP cells in a concentration-dependent manner. KLT suppressed the expression of MDR1 and MRP1 and the level of PVT1. PVT1 overexpression reversed the increased percentage of apoptotic cells induced by KLT. Finally, we found that PVT1 overexpression also abrogated the effect of KLT on the mRNA level and protein level of MDR1 and MRP1 in BGC823/DPP and SGC7901/DDP cells. KLT inhibited the expression of MDR1 and MRP1 via suppressing the expression of PVT1, which suggested the potential mechanism of KLT involving in MDR in gastric cancer.

The effects of SAHA on radiosensitivity in pancreatic cancer cells by inducing apoptosis and targeting RAD51

Suberoyl anilide hydroxamic acid (SAHA) is one of the most promising Histone deacetylases(HDAC) inhibitors which has shown significant anti-tumor activity for many malignancies. We explored the potential mechanism of the radiosensitivity effect of SAHA in Panc-1 cells and attempted to develop SAHA as a systemic treatment strategy for pancreatic cancer. Growth inhibition was detected by CCK-8 assay. Radiosensitizing enhancement ratio was determined by clonogenic assay. The cell cycle and apoptosis assay was detected using flow cytometry and annexin-V/PI. The level of Bax, Bcl-2, Ku70, Ku86, RAD51, RAD54 protein expression were detected using Western blot analysis. Gene silencing was processed by lentiviral vector and qRT-PCR was performed to detect mRNA expression. The results revealed that SAHA inhibited the proliferation of Panc-1 cells. SAHA enhanced the radiosensitivity with a sensitization enhancement ratio(SER) of 1.10 of the Panc-1 cells. SAHA induced G2-M phase arrest and apoptosis of Panc-1 cells with radiation. SAHA upregulated Bax and downregulated Bcl-2, Ku70, Ku86, RAD51, RAD54 protein expression of irradiated Panc-1 cells. SAHA enhanced the radiosensitivity of Panc-1 cells by modulating RAD51 expression. SAHA enhanced radiosensitivity to pancreatic carcinoma Panc-1 cells. It was associated with the G2-M phase arrest and apoptosis via modulation of Bax and Bcl-2 expression. Downregulation of Ku70, Ku86, RAD51 and RAD54 expression caused suppression of HR-mediated DNA repair. SAHA is a good radiosensitizer for pancreatic cancer treatment.

Effective PI3K modulators for improved therapy against malignant tumors and for neuroprotection of brain damage after tumor therapy (Review)

Due to the key role in various cellular processes including cell proliferation and cell survival on many cell types, dysregulation of the PI3K/AKT pathway represents a crucial step of the pathogenesis in many diseases. Furthermore, the tumor suppressor PTEN negatively regulates the PI3K/AKT pathway through its lipid phosphatase activity, which is recognized as one of the most frequently deleted and/or mutated genes in human cancer. Given the pervasive involvement of this pathway, the development of the molecules that modulate this PI3K/AKT signaling has been initiated in studies which focus on the extensive effective drug discovery. Consequently, the PI3K/AKT pathway appears to be an attractive pharmacological target both for cancer therapy and for neurological protection necessary after the therapy. A better understanding of the molecular relations could reveal new targets for treatment development. We review recent studies on the features of PI3K/AKT and PTEN, and their pleiotropic functions relevant to the signaling pathways involved in cancer progress and in neuronal damage by the therapy.