A small compound spindlactone A sensitizes human endometrial cancer cells to TRAIL-induced apoptosis via the inhibition of NAD(P)H dehydrogenase quinone 1

Combinatorial Implications of Nrf2 Inhibitors with FN3K Inhibitor: In vitro Breast Cancer Study

BACKGROUND

Platinum derivatives are chemotherapeutic agents preferred for the treatment of cancers including breast cancer. Oxaliplatin is an anticancer drug that is in phase II studies to treat metastatic breast cancer. However, its usage is constrained by chemoresistance and dose-related side effects.

OBJECTIVE

The objective of this study is to examine the combinatorial efficacy of brusatol, an Nrf2 blocker, with oxaliplatin (a proven FN3K blocker in our study) in mitigating breast cancer growth in vitro.

METHODS

We performed cytotoxicity assays, combination index (CI) analysis, colony formation assays, apoptosis assays, and Western blotting.

RESULTS

Results of our study described the chemosensitizing efficacy of brusatol in combination with lowdose oxaliplatin against breast cancer through synergistic effects in both BT-474 and T47D cells. A significant mitigation in the migration rate of these cancer cells was observed with the combination regimen, which is equivalent to the IC-50 dose of oxaliplatin (125 μM). Furthermore, ROS-mediated and apoptotic modes of cell death were observed with a combinatorial regimen. Colony formation of breast cancer cell lines was mitigated with a combinatorial regimen of bursatol and oxaliplatin than the individual treatment regimen. FN3K expression downregulated with oxaliplatin in T47D cells. The mitigation of FN3K protein expression with a combination regimen was not observed but the Nrf2 downstream antioxidant signaling proteins were significantly downregulated with a combination regimen similar to individual drug regimens.

CONCLUSION

Our study concluded the combination efficacy of phytochemicals like brusatol in combination with low-dose oxaliplatin (FN3K blocker), which could enhance the chemosensitizing effect in breast cancer and minimize the overall dose requirement of oxaliplatin.

Dicoumarol: from chemistry to antitumor benefits

Dicoumarol, a coumarin-like compound, is known for its anticoagulant properties associated with the ability to inhibit vitamin K, being prescribed as a drug for several decades. The pharmaceutical value of dicoumarol turned it into a focus of chemists' attention, aiming its synthesis and of dicoumarol derivatives, bringing to light new methodologies. In recent years, several other bioactive effects have been claimed for dicoumarol and its derivatives, including anti-inflammatory, antimicrobial, antifungal, and anticancer, although the mechanisms of action underlying them are mostly not disclosed and additional research is needed to unravel them. This review presents a state of the art on the chemistry of dicoumarols, and their potential anticancer characteristics, highlighting the mechanisms of action elucidated so far. In parallel, we draw attention to the lack of in vivo studies and clinical trials to assess the safety and efficacy as drugs for later application.

Targeted Inhibition of Anti-Inflammatory Regulator Nrf2 Results in Breast Cancer Retardation In Vitro and In Vivo

Nuclear factor erythroid-2 related factor-2 (Nrf2) is an oxidative stress-response transcriptional activator that promotes carcinogenesis through metabolic reprogramming, tumor promoting inflammation, and therapeutic resistance. However, the extension of Nrf2 expression and its involvement in regulation of breast cancer (BC) responses to chemotherapy remain largely unclear. This study determined the expression of Nrf2 in BC tissues (n = 46) and cell lines (MDA-MB-453, MCF-7, MDA-MB-231, MDA-MB-468) with diverse phenotypes. Immunohistochemical (IHC)analysis indicated lower Nrf2 expression in normal breast tissues, compared to BC samples, although the difference was not found to be significant. However, pharmacological inhibition and siRNA-induced downregulation of Nrf2 were marked by decreased activity of NADPH quinone oxidoreductase 1 (NQO1), a direct target of Nrf2. Silenced or inhibited Nrf2 signaling resulted in reduced BC proliferation and migration, cell cycle arrest, activation of apoptosis, and sensitization of BC cells to cisplatin in vitro. Ehrlich Ascites Carcinoma (EAC) cells demonstrated elevated levels of Nrf2 and were further tested in experimental mouse models in vivo. Intraperitoneal administration of pharmacological Nrf2 inhibitor brusatol slowed tumor cell growth. Brusatol increased lymphocyte trafficking towards engrafted tumor tissue in vivo, suggesting activation of anti-cancer effects in tumor microenvironment. Further large-scale BC testing is needed to confirm Nrf2 marker and therapeutic capacities for chemo sensitization in drug resistant and advanced tumors.

Limonin induces apoptosis of HL-60 cells by inhibiting NQO1 activity

Limonin is an important bioactive substance in citrus fruits, especially in seeds, which has great potential in cancer prevention and treatment. In order to explore the anticancer activity based on interaction between limonin and NQO1, Human promyelocytic leukemia cells (HL-60) were studied in vitro. We found that limonin could inhibit proliferation and promote apoptosis of HL-60 cells, and the effect was positively correlated with its dosage. Western blot results showed that limonin could activate the endogenous apoptosis pathway mediated by mitochondria via up-regulating pro-apoptotic proteins (Bax, cytochrome c, Caspase3, and Caspase9) and down-regulating anti-apoptotic proteins (Bcl-2), thus inhibiting the proliferation of HL-60 cells and promoting apoptosis, which further proved the anticancer activity of limonin from the molecular mechanism. At the same time, limonin down-regulated the expression of NQO1, indicating that limonin may indirectly act on the apoptosis pathway by regulating the expression activity of antioxidant enzymes in vivo, thus exerting its inhibitory effect on tumor cells, which provides an idea for the molecular mechanism that natural products can indirectly exert their anticancer effect by regulating the activity of antioxidant enzymes.