Effects of 17-allylamino-17-demethoxygeldanamycin on the induction of apoptosis and cell cycle arrest in HCT-116 cells

Novel tropane analogues as Hsp90 inhibitors targeting colon cancer: Synthesis, biological estimation, and molecular docking study

New derivatives of tropane scaffold were prepared from the reaction of their thione or thioamide derivatives with α-halocarbonyl compounds. The structures of all new derivatives were assured and proved with their spectral data. The novel tropane derivatives were examined for their cytotoxicity on two colon tumor cell lines; Caco2 and HCT116 cells. The most active compounds 3, 4, 5, 9d and 14a displayed significant antitumor activities with IC50 range of 9.50 - 30.15 μM compared to doxorubicin. Moreover, they revealed reduced cytotoxic effect on WI-38 normal ones, signifying their great safety. With the aim of better understanding the inhibitory potential of such compounds on heat-shock protein 90 (Hsp90), there activities were assessed against such enzyme demonstrating high inhibitory activities with IC50 range of 56.58-78.85 nM. Western blotting was carried out to ensure the inhibitory activity on Hsp90, results showed that 3 markedly suppressed Hsp90 expression on Caco2 cell line. Additionally, a molecular docking analysis of the most potent derivatives at the Hsp90 binding site was carried out in order to approve the performed in vitro assays.

Aa-Z2 triggers ROS-induced apoptosis of osteosarcoma by targeting PDK-1

BACKGROUND

Osteosarcoma (OS) is the most frequent cancer derived from bone, and the prognosis of OS is poor. Metabolic alterations have been previously reported to contribute to the development of OS, and arsenic compounds have been suggested to exhibit strong anti-OS effects. However, few studies have described the therapeutic efficiency of arsenic compounds by targeting metabolism in OS.

METHODS

Here, we presented a novel organo-arsenic compound, Aa-Z2, and its antitumour efficacy against OS both in vitro and in vivo.

RESULTS

Aa-Z2 induced OS cell apoptosis, G2/M phase arrest, and autophagy through the accumulation of reactive oxygen species (ROS). Elevated ROS functioned by promoting the mitochondrial-dependent caspase cascade and attenuating the PI3K/Akt/mTOR signalling pathway. N-acetylcysteine (NAC), a kind of ROS scavenger, could reverse the effects of Aa-Z2 treatment on 143B and HOS cells. Specifically, by targeting pyruvate dehydrogenase kinase 1 (PDK-1), Aa-Z2 induced changes in mitochondrial membrane potential and alterations in glucose metabolism to accumulate ROS. Overexpression of PDK-1 could partially desensitize OS cells to Aa-Z2 treatment. Importantly, Aa-Z2 suppressed tumour growth in our xenograft osteosarcoma model.

CONCLUSION

The study provides new insights into the mechanism of Aa-Z2-related metabolic alterations in OS inhibition, as well as pharmacologic evidence supporting the development of metabolism-targeting therapeutics.

Ins and Outs of Heat Shock Proteins in Colorectal Carcinoma: Its Role in Carcinogenesis and Therapeutic Perspectives

Cancer cells can reprogram their metabolic activities and undergo uncontrolled proliferation by utilizing the power of heat shock proteins (HSPs). HSPs are highly conserved chaperones that facilitate the folding of intracellular proteins under stress. Constitutively, HSPs are expressed at low levels, but their expression upregulates in response to a wide variety of insults, including anticancer drugs, allowing cancer cells to develop chemoresistance. In recent years, several researchers have reported that HSPs could be an important therapeutic target in difficult-to-treat cancers such as colorectal carcinoma (CRC). Worldwide, CRC is the second most common type of cancer and the second leading cause of cancer-related deaths. The molecular complexity of CRC and the coexisting inflammatory conditions present a significant obstacle to developing effective treatment. Recently, considerable progress has been made in enhancing our understanding of the role of HSPs in CRC pathogenesis. Moreover, novel therapeutic strategies targeting HSPs, either alone or in combination with other anticancer agents, have been reported. Herein, we present an overview of the functional mechanisms and the diagnostic and prognostic potential of HSPs in CRC. We also discuss emerging anti-CRC strategies based on targeting HSPs.

The Effects of Lactobacillus plantarum-12 Crude Exopolysaccharides on the Cell Proliferation and Apoptosis of Human Colon Cancer (HT-29) Cells

The exopolysaccharide (EPS) of some Lactobacillus strains has been reported to exert anti-cancer activities. In this study, the effects of crude EPSs produced by four Lactobacillus plantarum strains (Lactobacillus plantarum-12, L. plantarum-14, L. plantarum-32, and L. plantarum-37) on HT-29 cell proliferation and apoptosis were studied. The results showed that the inhibition rate of the crude EPS produced by L. plantarum-12 on HT-29 cell proliferation was significantly higher than that of the EPS produced by the other three strains. L. plantarum-12 crude EPS (50, 100, 250, 500 μg/ml) exerted inhibitory effects on the expression of proliferating cell nuclear antigen (PCNA) in HT-29 cells in a positive dose-dependent manner. The reactive oxygen species (ROS) level and apoptosis rate were also increased in HT-29 cells treated with different concentrations of L. plantarum-12 crude EPS compared with control cells. Further studies found that the expression of the pro-apoptotic proteins Bax, Cyt C, caspase-3, caspase-8 and caspase-9 was upregulated and that the expression of the anti-apoptosis protein Bcl-2 was decreased in HT-29 cells treated with L. plantarum-12 crude EPS compared with control cells. The results suggested that the EPS produced by L. plantarum-12 could inhibit the proliferation of the human colon cancer cell line HT-29 through the mitochondrial pathway.

Anti-cancer Effects of a Neutral Triterpene Fraction from Ganoderma lucidum and its Active Constituents on SW620 Human Colorectal Cancer Cells

Background:

Ganoderma lucidum (Leyss. ex Fr.) Karst. (G. lucidum, GL) belongs to the family of Ganodermataceae (Basidiomycetes), and possesses activities including antitumor, antimicrobial, antiviral, and antiaging activities. Triterpenoids are typical chemical constituents in G. lucidum, and play an important role in the anti-cancer effects. According to the substituent group at the carbon 26 position, GL total triterpenes fraction can be divided into two types, Neutral Triterpene Fraction (NTF) and an Acidic Triterpene Fraction (ATF). The anti-cancer effects of total triterpenes fraction and total acidic triterpene fraction extracted from G. lucidum have been widely known in vivo and in vitro, whereas few have focused on total neutral triterpene fraction.

Objective:

The aim of this study was to evaluate the anti-cancer effects of NTF extracted from G. lucidum in vitro and in vivo and explore its anti-cancer active constituents on SW620 human colorectal cancer cells.

Methods:

NTF and ATF were extracted from the dry fruiting body of G. lucidum by impregnation method with 90% ethanol, and further isolated by using alkaline extraction and acid precipitation method. The total triterpenoid content of NTF and ATF was determined by using ultraviolet-visible spectrophotometry. The cytotoxic effects on human colon cancer cells SW480, SW620, SW1116, and mouse embryonic fibroblast cell line NIH3T3 were evaluated by using the MTT method. The anti-cancer activity of NTF in vivo was evaluated in Athymic nude mice against SW620 cells. An activity-guided separation and purification process were used to identify the anti-cancer active constituents of NTF by column and preparative high-performance liquid chromatography. Structures of the constituents were confirmed by 1H-NMR, 13C-NMR and MS. Protein expression was performed by Western blotting.

Results:

The percentage of total triterpenoids was 46.7% and 57.6% in ATF and NTF, respectively. Both fractions could reduce the viability of SW480, SW620, and SW1116 cells in vitro, whereby NTF exhibited a stronger effect than ATF. NTF markedly inhibited the growth of SW620 cell xenografts in mice at doses (250, 500mg/kg) during the treatment. Furthermore, a new garnoderic alcohol, named as ethyl ganoderate A and eight known ganoderic alcohols were isolated and identified from NTF by a bioassay-guided separation process. All of these compounds possessed anti-cancer activities against SW620 cells in vitro. As a representative ganoderma alcohol, ganodermanondiol significantly reduced the viability of SW620 cells through the induction of apoptosis, which was associated with the upregulated the levels of cleaved-poly (ADP-ribose) polymerase (PARP), cleaved-caspase-3, and -9. In addition, ganodermanondiol showed low cytotoxic activity against normal NIH3T3 cells.

Conclusion:

NTF are potential anti-cancer agents against colon cancer and the active constituents may be ganoderic alcohols whose inhibitory mechanism of anti-cancer action may be related to the activation of a mitochondrial- dependent pathway.

Anti-cancer effects of chemotherapeutic agent; 17-AAG, in combined with gold nanoparticles and irradiation in human colorectal cancer cells

OBJECTIVE

The present study evaluated the anti-cancer effects of irradiation (Ir) alone, Ir after heat shock protein 90 inhibitor; 17-allylamino-17-demethoxygeldanamycin (17-AAG) and gold nanoparticle (GNP) treatments in human colorectal cancer cell line (HCT-116), with the targeting of related mechanisms.

METHODS

Water-soluble tetrazolium salt-1 assay was utilized to study the cytotoxic effects of 17-AAG, GNP, Ir in single and combination cases on the cell viability of HCT-116 cells. The cells were examined with DNA fragmentation electrophoresis and evaluated for apoptosis induction. Caspase-3 expression as a critical apoptosis element in protein level was detected by western blotting.

RESULTS

Treatment with 17-AAG in a dose dependent manner for 24 h inhibited the cellular viability of HCT-116 cells. GNP at a dose of 70 μM had the lowest cytotoxic effects and was thus selected for combination treatment studies. Based on the results, GNP at a dose of 70 μM did not have a significant effect on cellular viability of HCT-116. In contrast, the evaluation of double and triple combinations, GNP with Ir (2 Gy of 6 MV X-ray radiation) and 17-AAG in double combinations induced significant cytotoxicity. Both DNA damage pattern and caspase-3 protein upregulation were present in Ir,GNP/17-AAG,GNP and Ir,17-AAG combinations compared to single treatments. Furthermore, in the three combination of GNP,Ir,17-AAG, radiosensitization effects (increased caspase-3 expression) occurred with a minimum concentration of 17-AAG.

CONCLUSION

According to the results of this study, 17-AAG as chemotherapeutic agent in combination with Ir and GNP exerts noticeable anti-cancer effects, inhibited cell viability, and increased apoptosis occurrence by upregulating caspase-3 expression. It is suggested that these combinations should be more evaluated as a promising candidate for colorectal cancer treatment. Graphical abstract Anti-cancer effects of chemotherapeutic agent; 17-AAG, in combined with gold nanoparticles and irradiation in human colorectal cancer cells.

Heat shock protein 90α couples with the MAPK-signaling pathway to determine meiotic maturation of porcine oocytes

Heat shock protein 90 (Hsp90) functions as a molecular chaperone in its interaction with clients to influence multiple cellular and physiological processes. However, our current understanding on Hsp90's relationship with mammalian oocyte maturation is still very limited. Here, we aimed to investigate Hsp90's effect on pig oocyte meiotic maturation. Endogenous Hsp90α was constantly expressed at both mRNA and protein levels in porcine maturing oocytes. Addition of 2 µM 17-allylamino-17-demethoxygeldanamycin (17-AAG), the Hsp90 inhibitor, to in vitro mature cumulus-oocyte complexes (COC) significantly decreased Hsp90α protein level (P < 0.05), delayed germinal vesicle breakdown (GVBD) (P < 0.05), and impeded the first polar body (PB1) extrusion (P < 0.01) of porcine oocytes. 2 µM 17-AAG treatment during in vitro maturation also decreased the subsequent development competence as indicated by the lower cleavage (P < 0.001) and higher fragmentation (P < 0.001) rates of parthenotes, whereas no effects on the percentage and average cell number of blastocysts were found. Immunodepletion of Hsp90α by antibody microinjection into porcine oocytes at germinal vesicle and metaphase II stages induced similar defects of meiotic maturation and parthenote development, to that resulted from 2 µM inhibitor 17-AAG. For oocytes treated by 2 µM 17-AAG, the cytoplasm and membrane actin levels were weakened (P < 0.01), and the spindle assembly was disturbed (P < 0.05), due to decreased p-ERK1/2 level (P < 0.05). However, the mitochondrial function and early apoptosis were not affected, as demonstrated by rhodamine 123 staining and Annexin V assays. Our findings indicate that Hsp90α can couple with mitogen-activated protein kinase to regulate cytoskeletal structure and orchestrate meiotic maturation of porcine oocytes.