Concurrent blockade of NF-κB and Akt pathways potentiates cisplatin’s antitumor activity in vivo

Rosmanol induces breast cancer cells apoptosis by regulating PI3K/AKT and STAT3/JAK2 signaling pathways

Breast cancer is one of the most frequently diagnosed cancers amongst women; however, there is currently no effective treatment. Natural compounds are considered to contribute to cancer prevention and have a pivotal role in modulating apoptosis. Rosmanol is a phenolic diterpene compound with antioxidant and anti-inflammatory properties. In the present study, the effects of Rosmanol on breast cancer cell proliferation/apoptosis were investigated, and it was demonstrated that it inhibited the proliferation of MCF-7 and MDA-MB 231 cells but did not have a significant effect on normal human breast MCF-10A cells. In addition, the apoptotic process was accelerated by Rosmanol, through mitochondrial pathways and reactive oxygen species (ROS) production caused by DNA damage, which function further demonstrated by the attenuation and addition of the ROS inhibitor, N-acetyl-cysteine. It was also demonstrated that Rosmanol accelerated cell apoptosis, and arrested breast cancer cells in the S phase. Moreover, Rosmanol inhibited proliferation and promoted apoptosis of cancer cells via the inhibition of ERK and STAT3 signals, attributable to the increase in p-p38, the overexpression of protein inhibitor of activated STAT3, and the decrease in PI3K/AKT, ERK and JAK2/STAT3.

Astragaloside IV enhanced carboplatin sensitivity in prostate cancer by suppressing AKT/NF-κB signaling pathway

In our study, we explored the effect of astragaloside IV (AgIV) on carboplatin chemotherapy in prostate cancer cell lines in vitro and in vivo. Cell viability assay, colony formation assay, flow cytometry, Western blot, immunohistochemistry, immunofluorescence, and tumor xenograft growth assay were conducted. We found that AgIV significantly decreased the half-maximal inhibitory concentration of carboplatin in prostate cancer cell lines LNCap and PC-3. Moreover, AgIV enhanced the effect of carboplatin in suppressing colony formation and inducing cell apoptosis. A low-dose carboplatin treatment upregulated N-cadherin and Vimentin expression and downregulated E-cadherin expression, but this effect was abolished by combining with AgIV. Carboplatin treatment increased the levels of p-AKT and p-p65 and decreased p-IκBα, but AgIV treatment suppressed this. In addition, AgIV synergized with carboplatin to suppress tumor xenograft growth of PC-3 cells, and decreased pAKT and p-p65 levels in vivo. Our results suggested that AgIV enhanced carboplatin sensitivity in prostate cancer cell lines by suppressing AKT/NF-κB signaling, thus suppressed epithelial-mesenchymal transition induced by carboplatin. Our findings provided a new mechanism for AgIV in overcoming drug resistance of platinum-based chemotherapy and suggested a potential combination therapy of AgIV and carboplatin in prostate cancer.

Expression of NF-κB and PTEN in osteosarcoma and its clinical significance

We investigated the role of nuclear factor-κB (NF-κB) and phosphatase and tensin homolog deleted in chromosome 10 (PTEN) in the pathogenesis of osteosarcoma and its relationship with prognosis. Immunohistochemical method was used to detect the expression of NF-κB and PTEN in osteosarcoma and adjacent tissues. RT-PCR was used to detect the expression of NF-κB and PTEN mRNA in osteosarcoma and adjacent tissues. Western blotting was used to detect the expression of NF-κB and PTEN in osteosarcoma and adjacent tissues and compare their differences. The expression of NF-κB and PTEN was detected in osteosarcoma and adjacent tissues. The positive rate of NF-κB was 75.3 and 32.9%, respectively; while the positive rate of PTEN was 67.1 and 90.4%, respectively. The positive expression of NF-κB and PTEN was statistically significant. There was a negative correlation between NF-κB and PTEN expression (r=-0.502, p<0.05). The positive and negative expression of NF-κB and PTEN was statistically significant for the five-year survival (p<0.05). At gene and protein level, osteosarcoma tissues had higher expression of NF-κB, and lower expression of PTEN, which was significantly different from the adjacent tissues. In osteosarcoma, NF-κB is highly expressed, but PTEN is expressed at low level, and the two are negatively correlated. This is of great significance for the early diagnosis of osteosarcoma and prognosis.

Histone H4 expression is cooperatively maintained by IKKβ and Akt1 which attenuates cisplatin-induced apoptosis through the DNA-PK/RIP1/IAPs signaling cascade

While chromatin remodeling mediated by post-translational modification of histone is extensively studied in carcinogenesis and cancer cell’s response to chemotherapy and radiotherapy, little is known about the role of histone expression in chemoresistance. Here we report a novel chemoresistance mechanism involving histone H4 expression. Extended from our previous studies showing that concurrent blockage of the NF-κB and Akt signaling pathways sensitizes lung cancer cells to cisplatin-induced apoptosis, we for the first time found that knockdown of Akt1 and the NF-κB-activating kinase IKKβ cooperatively downregulated histone H4 expression, which increased cisplatin-induced apoptosis in lung cancer cells. The enhanced cisplatin cytotoxicity in histone H4 knockdown cells was associated with proteasomal degradation of RIP1, accumulation of cellular ROS and degradation of IAPs (cIAP1 and XIAP). The cisplatin-induced DNA-PK activation was suppressed in histone H4 knockdown cells, and inhibiting DNA-PK reduced expression of RIP1 and IAPs in cisplatin-treated cells. These results establish a novel mechanism by which NF-κB and Akt contribute to chemoresistance involving a signaling pathway consisting of histone H4, DNA-PK, RIP1 and IAPs that attenuates ROS-mediated apoptosis, and targeting this pathway may improve the anticancer efficacy of platinum-based chemotherapy.

Minnelide/Triptolide Impairs Mitochondrial Function by Regulating SIRT3 in P53-Dependent Manner in Non-Small Cell Lung Cancer

Minnelide/Triptolide (TL) has recently emerged as a potent anticancer drug in non-small cell lung cancer (NSCLC). However, the precise mechanism of its action remains ambiguous. In this study, we elucidated the molecular basis for TL-induced cell death in context to p53 status. Cell death was attributed to dysfunction of mitochondrial bioenergetics in p53-deficient cells, which was characterized by decreased mitochondrial respiration, steady-state ATP level and membrane potential, but augmented reactive oxygen species (ROS). Increased ROS production resulted in oxidative stress in TL-treated cells. This was exhibited by elevated nuclear levels of a redox-sensitive transcriptional factor, NF-E2-related factor-2 (NRF2), along with diminished cellular glutathione (GSH) content. We further demonstrated that in the absence of p53, TL blunted the expression of mitochondrial SIRT3 triggering increased acetylation of NDUAF9 and succinate dehydrogenase, components of complexes I and II of the electron transport chain (ETC). TL-mediated hyperacetylation of complexes I and II proteins and these complexes displayed decreased enzymatic activities. We also provide the evidence that P53 regulate steady-state level of SIRT3 through Proteasome-Pathway. Finally, forced overexpression of Sirt3, but not deacetylase-deficient mutant of Sirt3 (H243Y), restored the deleterious effect of TL on p53-deficient cells by rescuing mitochondrial bioenergetics. On contrary, Sirt3 deficiency in the background of wild-type p53 triggered TL-induced mitochondrial impairment that echoed TL effect in p53-deficeint cells. These findings illustrate a novel mechanism by which TL exerts its potent effects on mitochondrial function and ultimately the viability of NSCLC tumor.

Sensitization of ovarian cancer cells to cisplatin by gold nanoparticles

Recently we reported that gold nanoparticles (AuNPs) inhibit ovarian tumor growth and metastasis in mice by reversing epithelial-mesenchymal transition (EMT). Since EMT is known to confer drug resistance to cancer cells, we wanted to investigate whether anti-EMT property of AuNP could be utilized to sensitize ovarian cancer cells to cisplatin. Herein, we report that AuNPs prevent cisplatin-induced acquired chemoresistance and stemness in ovarian cancer cells and sensitize them to cisplatin. AuNPs inhibit cisplatin induced EMT, decrease the side population cells and key stem cell markers such as ALDH1, CD44, CD133, Sox2, MDR1 and ABCG2 in ovarian cancer cells. Mechanistically, AuNPs prevent cisplatin-induced activation of Akt and NF-κB signaling axis in ovarian cancer cells that are critical for EMT, stem cell maintenance and drug resistance. In vivo, AuNPs sensitize orthotopically implanted ovarian tumor to a low dose of cisplatin and significantly inhibit tumor growth via facilitated delivery of both AuNP and cisplatin. These findings suggest that by depleting stem cell pools and inhibiting key molecular pathways gold nanoparticles sensitize ovarian cancer cells to cisplatin and may be used in combination to inhibit tumor growth and metastasis in ovarian cancer.

Curcumin sensitizes human lung cancer cells to apoptosis and metastasis synergistically combined with carboplatin

Although carboplatin is one of the standard chemotherapeutic agents for non-small cell lung cancer (NSCLC), it has limited therapeutic efficacy due to activation of a survival signaling pathway and the induction of multidrug resistance. Curcumin, a natural compound isolated from the plant Curcuma longa, is known to sensitize tumors to different chemotherapeutic agents. The aim of this study is to evaluate whether curcumin can chemosensitize lung cancer cells to carboplatin and to analyze the signaling pathway underlying this synergism. We investigated the synergistic effect of both agents on cell proliferation, apoptosis, invasion, migration, and expression of related signaling proteins using the human NSCLC cell line, A549. A549 cell was treated with different concentrations of curcumin and carboplatin alone and in combination. Combined treatment with curcumin and carboplatin inhibited tumor cell growth, migration, and invasion compared with either drug alone. Matrix metalloproteinase (MMP)-2 and MMP-9 were more efficiently downregulated by co-treatment than by each treatment alone. mRNA and protein expression of caspase-3 and caspase-9 and proapoptotic genes was increased in cells treated with a combination of curcumin and carboplatin, whereas expression of the antiapoptotic Bcl-2 gene was suppressed. Co-treatment of both agents substantially suppressed NF-κB activation and increased expression of p53. Phosphorylation of Akt, a protein upstream of NF-κB, was reduced, resulting in inhibition of the degradation of inhibitor of κB(IκBα), whereas the activity of extracellular signal-regulated kinase (ERK1/2) was enhanced. Our study demonstrated that the synergistic antitumor activity of curcumin combined with carboplatin is mediated by multiple mechanisms involving suppression of NF-κB via inhibition of the Akt/IKKα pathway and enhanced ERK1/2 activity. Based on this mechanism, curcumin has potential as a chemosensitizer for carboplatin in the treatment of patients with NSCLC.

Minnelide: a novel therapeutic that promotes apoptosis in non-small cell lung carcinoma in vivo

BACKGROUND

Minnelide, a pro-drug of triptolide, has recently emerged as a potent anticancer agent. The precise mechanisms of its cytotoxic effects remain unclear.

METHODS

Cell viability was studied using CCK8 assay. Cell proliferation was measured real-time on cultured cells using Electric Cell Substrate Impedence Sensing (ECIS). Apoptosis was assayed by Caspase activity on cultured lung cancer cells and TUNEL staining on tissue sections. Expression of pro-survival and anti-apoptotic genes (HSP70, BIRC5, BIRC4, BIRC2, UACA, APAF-1) was estimated by qRTPCR. Effect of Minnelide on proliferative cells in the tissue was estimated by Ki-67 staining of animal tissue sections.

RESULTS

In this study, we investigated in vitro and in vivo antitumor effects of triptolide/Minnelide in non-small cell lung carcinoma (NSCLC). Triptolide/Minnelide exhibited anti-proliferative effects and induced apoptosis in NSCLC cell lines and NSCLC mouse models. Triptolide/Minnelide significantly down-regulated the expression of pro-survival and anti-apoptotic genes (HSP70, BIRC5, BIRC4, BIRC2, UACA) and up-regulated pro-apoptotic APAF-1 gene, in part, via attenuating the NF-κB signaling activity.

CONCLUSION

In conclusion, our results provide supporting mechanistic evidence for Minnelide as a potential in NSCLC.

Cellular and molecular mechanisms underlie the anti-tumor activities exerted by Walterinnesia aegyptia venom combined with silica nanoparticles against multiple myeloma cancer cell types

Multiple myeloma (MM) is a clonal disease of plasma cells that remains incurable despite the advent of several novel therapeutics. In this study, we aimed to delineate the impact of snake venom extracted from Walterinnesia aegyptia (WEV) alone or in combination with silica nanoparticles (WEV+NP) on primary MM cells isolated from patients diagnosed with MM as well as on two MM cell lines, U266 and RPMI 8226. The IC₅₀ values of WEV and WEV+NP that significantly decreased MM cell viability without affecting the viability of normal peripheral mononuclear cells (PBMCs) were determined to be 25 ng/ml and 10 ng/ml, respectively. Although both WEV (25 ng/ml) and WEV+NP (10 ng/ml) decreased the CD54 surface expression without affecting the expression of CXCR4 (CXCL12 receptor) on MM cells, they significantly reduced the ability of CXC chemokine ligand 12 (CXCL12) to induce actin cytoskeleton rearrangement and the subsequent reduction in chemotaxis. It has been established that the binding of CXCL12 to its receptor CXCR4 activates multiple intracellular signal transduction pathways that regulate MM cell chemotaxis, adhesion, and proliferation. We found that WEV and WEV+NP clearly decreased the CXCL12/CXCR4-mediated activation of AKT, ERK, NFκB and Rho-A using western blot analysis; abrogated the CXCL12-mediated proliferation of MM cells using the CFSE assay; and induced apoptosis in MM cell as determined by PI/annexin V double staining followed by flow cytometry analysis. Monitoring the expression of B-cell CCL/Lymphoma 2 (Bcl-2) family members and their role in apoptosis induction after treatment with WEV or WEV+NP revealed that the combination of WEV with NP robustly decreased the expression of the anti-apoptotic effectors Bcl-2, Bcl_XL and Mcl-1; conversely increased the expression of the pro-apoptotic effectors Bak, Bax and Bim; and altered the mitochondrial membrane potential in MM cells. Taken together, our data reveal the biological effects of WEV and WEV+NP and the underlying mechanisms against myeloma cancer cells.