Metabolites from the plant endophytic fungus Penicillium sp. CPCC 401423 and their cytotoxic activity against MIA PaCa-2 cells.

Twenty-two metabolites were isolated from Penicillium sp. CPCC 401423 cultured on rice. The structures of all compounds were elucidated mainly by MS and NMR analysis as well as the necessary CD experimental evidence, of which penicillidione A (1), penicillidione B (2), (E)-4-[(4-acetoxy-3-methyl-2-butenyl)oxy]phenylacetic acid (3), (S)-2-hydroxy-2-{4-[(3-methyl-2-butenyl)oxy]phenyl} (4), (S)-4-(2,3-dihydroxy-3-methyl-butoxy)phenylacetic acid (5), (E)-4-[(3-carboxy-2-butenyl)oxy]benzoic acid (6), (Z)-4-[(4-hydroxy-3-methyl-2-butenyl)oxy]benzoic acid (7), open-cycled N-demethylmelearoride A (12), and penostatin M (16) were identified as new compounds. The cytotoxic activity against human pancreatic carcinoma cell line MIA PaCa-2a was detected. Among them, compounds 13-15 and 22 displayed significant cytotoxicity against MIA-PaCa-2 cells with IC50 values of 8.9, 36.5, 31.8, and 22.3 µM, respectively (positive control gemcitabine IC50 65.0 µM).

Mitochondria autophagy: a potential target for cancer therapy.

Mitophagy is a selective form of macroautophagy in which dysfunctional and damaged mitochondria can be efficiently degraded, removed and recycled through autophagy. Selective removal of damaged or fragmented mitochondria is critical to the functional integrity of the entire mitochondrial network and cells. In past decades, numerous studies have shown that mitophagy is involved in various diseases; however, since the dual role of mitophagy in tumour development, mitophagy role in tumour is controversial, and further elucidation is needed. That is, although mitophagy has been demonstrated to contribute to carcinogenesis, cell migration, ferroptosis inhibition, cancer stemness maintenance, tumour immune escape, drug resistance, etc. during cancer progression, many research also shows that to promote cancer cell death, mitophagy can be induced physiologically or pharmacologically to maintain normal cellular metabolism and prevent cell stress responses and genome damage by diminishing mitochondrial damage, thus suppressing tumour development accompanying these changes. Signalling pathway-specific molecular mechanisms are currently of great biological significance in the identification of potential therapeutic targets. Here, we review recent progress of molecular pathways mediating mitophagy including both canonical pathways (Parkin/PINK1- and FUNDC1-mediated mitophagy) and noncanonical pathways (FKBP8-, Nrf2-, and DRP1-mediated mitophagy); and the regulation of these pathways, and abovementioned pro-cancer and pro-death roles of mitophagy. Finally, we summarise the role of mitophagy in cancer therapy. Mitophagy can potentially be acted as the target for cancer therapy by promotion or inhibition.

G3BP1 promotes human breast cancer cell proliferation through coordinating with GSK-3ß and stabilizing ß-catenin.

Ras-GTPase activating SH3 domain-binding protein 1 (G3BP1) is a multifunctional binding protein involved in the development of a variety of human cancers. However, the role of G3BP1 in breast cancer progression remains largely unknown. In this study, we report that G3BP1 is upregulated and correlated with poor prognosis in breast cancer. Overexpression of G3BP1 promotes breast cancer cell proliferation by stimulating ß-catenin signaling, which upregulates a number of proliferation-related genes. We further show that G3BP1 improves the stability of ß-catenin by inhibiting its ubiquitin-proteasome degradation rather than affecting the transcription of ß-catenin. Mechanistically, elevated G3BP1 interacts with and inactivates GSK-3ß to suppress ß-catenin phosphorylation and degradation. Disturbing the G3BP1-GSK-3ß interaction accelerates the degradation of ß-catenin, impairing the proliferative capacity of breast cancer cells. Our study demonstrates that the regulatory mechanism of the G3BP1/GSK-3ß/ß-catenin axis may be a potential therapeutic target for breast cancer.

The novel quinolizidine derivate IMB-HDC inhibits STAT5a phosphorylation at 694 and 780 and promotes DNA breakage and cell apoptosis via blocking STAT5a nuclear translocation.

Sophoridine is a quinolizidine natural product and the exploration of its derivatives has been carried out, and the potent anticancer compound IMB-HDC was acquired. Although previous studies have revealed that some sophoridine derivatives could induce DNA breakage, the underlying mechanisms of inhibition of DNA damage repair (ATR inactivation) and the apoptosis independent of p53, have not been elucidated. Our research reveals a novel DNA response mechanism different from general DNA-damaging agents, and that sophoridine derivate inhibits the phosphorylation of Tyr694 and Ser780 of STAT5a to induce the lessened shuttle from the cytoplasm to the nucleus, and leads to the decreased nuclear STAT5a and subsequently inhibits the expression of STAT5a target gene RAD51 that contributes to the checkpoint activation, thus inhibiting ATR activation. Meanwhile, IMB-HDC that induced the diminished expression of STAT5a target gene contributes to proliferation and leads to apoptosis. More importantly, we give the first evidence that promoting the effect of Tyr694 phosphorylation on nuclear location and subsequent STAT5a target gene transcription depends on Ser780 increased or unchanged phosphorylation and was not correlated with Ser726 phosphorylation.

Role and molecular mechanism of stem cells in colorectal cancer initiation.

In recent years, the rate of colorectal cancer has sharply increased, especially in China, where it ranks second for the number of cancer fatalities. Currently, the treatment of colorectal cancer patients involves the combination of resection surgery and treatment with postoperative anticancer drugs such as 5-FU and oxaliplatin. However, recurrence and metastasis after treatment are still the dominant reasons for the low survival rate. Colorectal cancer stem cells (CSCs) are regarded as the key contributors to tumour recurrence and metastasis due to their resistance to chemotherapy drugs and their extremely high tumourigenicity. Once CSCs overcome chemotherapy treatment, they continue to survive and reinitiate proliferation to form tumours, leading to recurrence. The dominant reason for CSC resistance is that most anticancer drugs are aimed at inhibiting proliferative pathways in cancer cells that differ from those in CSCs. Therefore, studies on the characteristics of CSCs and their intracellular molecular pathways are essential for the exploration of CSC-targeted drugs. In this report, we review recent advances in the research of CSCs and, in particular, review the important intracellular molecular pathways, such as HOXA5-catenin, STRAP-NOTCH and YAP/TAZ, related to the maintenance and differentiation of stem cells to generate a theoretical basis for the exploration of CSC-targeted drugs.

Role of co- and post-translational modifications of SFKs in their kinase activation.

Src family kinases (SFKs) are non-receptor tyrosine kinases and are involved in various cellular functions (proliferation, differentiation, migration, survival and invasion) by regulating downstream pathways. Considerable evidence suggests that co- and post-translational modifications are highly related to the activation of SFKs and their downstream signals. How SFKs are activated and how their subsequent cascades were regulated has been reviewed in previous reports. However, the contribution of co- and post-translational modification to SFKs activation has not been fully elucidated. This review focuses on the effect of these modifications on SFKs activity according to structural and biochemical studies and uncovers the significance of co-and post-translational modifications in the regulation of SFKs activity.

The roles and mechanisms of G3BP1 in tumour promotion.

Ras-GTPase-activating protein SH3 domain-binding protein 1 (G3BP1) is a SH3 domain-binding protein that is overexpressed in a variety of tumour tissues and cancers, such as head and neck cancer, lung cancer, prostate cancer, colon cancer and breast cancer. G3BP1 promotes tumour cell proliferation and metastasis and inhibits apoptosis by regulating the Ras, TGF-ß/Smad, Src/FAK and p53 signalling pathways. At present, polypeptides targeting G3BP1 have shown anti-tumour activity and G3BP1 also involved in anti-cancer effects of some polyphenolic compounds (resveratrol and EGCG). Therefore G3BP1 may be a potential target for tumour treatment.

D-chiro-inositol effectively attenuates cholestasis in bile duct ligated rats by improving bile acid secretion and attenuating oxidative stress.

Cholestatic liver diseases are important causes of liver cirrhosis and liver transplantation, but few drugs are available for treatment. D-chiro-inositol (DCI), an isomer of inositol found in many Leguminosae plants and in animal viscera, is used clinically for the treatment of polycystic ovary syndrome (PCOS) and diabetes mellitus. In this study, we investigated whether DCI exerted an anti-cholestatic effect and its underlying mechanisms. A cholestatic rat model was established via bile duct ligation (BDL). After the surgery, the rats were given DCI (150 mg·kg-1·d-1) in drinking water for 2 weeks. Oral administration of DCI significantly decreased the serum levels of alanine aminotransferase (ALT) and aspartate aminotransferase (AST), and attenuated bile duct proliferation, parenchymal necrosis and fibrosis in BDL rats. Furthermore, DCI treatment significantly increased the serum and bile levels of total bile acid (TBA), and decreased TBA levels in the liver. Moreover, DCI treatment significantly increased expression of the genes encoding bile acid transporters BSEP (Abcb11) and MRP2 (Abcc2) in liver tissues. DCI treatment also markedly decreased hepatic CD68 and NF-kappaB (NF-κB) levels, significantly decreased the serum and hepatic MDA levels, markedly increased superoxide dismutase activity in both serum and liver tissues. Using whole-genome oligonucleotide microarray, we revealed that DCI treatment altered the expression profiles of oxidation reduction-related genes in liver tissues. Collectively, DCI effectively attenuates BDL-induced hepatic bile acid accumulation and decreases the severity of injury and fibrosis by improving bile acid secretion, repressing inflammation and decreasing oxidative stress. The results suggest that DCI might be beneficial for patients with cholestatic disorders.

EBP50 suppresses the proliferation of MCF-7 human breast cancer cells via promoting Beclin-1/p62-mediated lysosomal degradation of c-Myc.

c-Myc, a key activator of cell proliferation and angiogenesis, promotes the development and progression of breast cancer. Ezrin-radixin-moesin-binding phosphoprotein-50 (EBP50) is a multifunctional scaffold protein that suppresses the proliferation of breast cancer cells. In this study we investigated whether the cancer-suppressing effects of EBP50 resulted from its regulation of c-Myc signaling in human breast cancer MCF-7 cells in vitro and in vivo. We first found a significant correlation between EBP50 and c-Myc expression levels in breast cancer tissue, and demonstrated that EBP50 suppressed cell proliferation through decreasing the expression of c-Myc and its downstream proteins cyclin A, E and Cdc25A in MCF-7 cells. We further showed that EBP50 did not regulate c-Myc mRNA expression, but it promoted the degradation of c-Myc through the autophagic lysosomal pathway. Moreover, EBP50 promoted integration between c-Myc and p62, an autophagic cargo protein, triggering the autophagic lysosomal degradation of c-Myc. In EBP50-silenced MCF-7 cells, activation of autophagy by Beclin-1 promoted the degradation of c-Myc and inhibited cell proliferation. These results demonstrate that the EBP50/Beclin-1/p62/c-Myc signaling pathway plays a role in the proliferation in MCF-7 breast cancer cells: EBP50 stimulates the autophagic lysosomal degradation of c-Myc, thereby inhibits the proliferation of MCF-7 cells. Based on our results, promoting the lysosomal degradation of c-Myc might be a promising new strategy for treating breast cancer.

SPHK1 (sphingosine kinase 1) induces epithelial-mesenchymal transition by promoting the autophagy-linked lysosomal degradation of CDH1/E-cadherin in hepatoma cells.

SPHK1 (sphingosine kinase 1), a regulator of sphingolipid metabolites, plays a causal role in the development of hepatocellular carcinoma (HCC) through augmenting HCC invasion and metastasis. However, the mechanism by which SPHK1 signaling promotes invasion and metastasis in HCC remains to be clarified. Here, we reported that SPHK1 induced the epithelial-mesenchymal transition (EMT) by accelerating CDH1/E-cadherin lysosomal degradation and facilitating the invasion and metastasis of HepG2 cells. Initially, we found that SPHK1 promoted cell migration and invasion and induced the EMT process through decreasing the expression of CDH1, which is an epithelial marker. Furthermore, SPHK1 accelerated the lysosomal degradation of CDH1 to induce EMT, which depended on TRAF2 (TNF receptor associated factor 2)-mediated macroautophagy/autophagy activation. In addition, the inhibition of autophagy recovered CDH1 expression and reduced cell migration and invasion through delaying the degradation of CDH1 in SPHK1-overexpressing cells. Moreover, the overexpression of SPHK1 produced intracellular sphingosine-1-phosphate (S1P). In response to S1P stimulation, TRAF2 bound to BECN1/Beclin 1 and catalyzed the lysine 63-linked ubiquitination of BECN1 for triggering autophagy. The deletion of the RING domain of TRAF2 inhibited autophagy and the interaction of BECN1 and TRAF2. Our findings define a novel mechanism responsible for the regulation of the EMT via SPHK1-TRAF2-BECN1-CDH1 signal cascades in HCC cells. Our work indicates that the blockage of SPHK1 activity to attenuate autophagy may be a promising strategy for the prevention and treatment of HCC.

Novel N-substituted sophoridinol derivatives as anticancer agents.

Using sophoridine (1) as the lead compound, a series of new N-substituted sophoridinic acid derivatives were designed, synthesized and evaluated for their cytotoxicity. SAR analysis indicated that introduction of a chlorobenzyl on the 12-nitrogen atom of sophoridinol might significantly enhance the antiproliferative activity. Of the newly synthesized compounds, sophoridinol analogue 9k exhibited a potent effect against six human tumor cell lines (liver, colon, breast, lung, glioma and nasopharyngeal). The mode of action of 9k was to inhibit the DNA topoisomerase I activity, followed by the G0/G1 phase arrest. It also showed a moderate oral bioavailability and good safety in vivo. Therefore, compound 9k has been selected as a novel-scaffold lead for further structural optimizations or as a chemical probe for exploring anticancer pathways of this kinds of compounds.

Discovery, synthesis and biological evaluation of cycloprotoberberine derivatives as potential antitumor agents.

A series of new 1,13-cycloprotoberberine derivatives defined through variations at the 9-position were designed, synthesized and evaluated for their cytotoxicities in human HepG2 (hepatoma), HT1080 (fibrosarcoma) and HCT116 (colon cancer) cells. The preliminary structure-activity relationship (SAR) revealed that the replacement of 9-methoxyl with an ester moiety might significantly enhance the antiproliferative activity in vitro. Notably, compound 7f demonstrated equipotent cytotoxicity activity against breast cancer MCF-7 (parent) and doxorubicin (DOX)-resistant MCF-7 (MCF-7/ADrR) cells, indicating a mode of action different from that of DOX. Further mechanism study showed that 7f significantly inhibited activity of DNA topoisomerase I (Top I) and Top II. G2/M phase arrest and tumor cell growth reduction was observed thereafter. Thus, we consider cycloprotoberberine analogues to be a new family of promising antitumor agents with an advantage of inhibiting drug-resistant cancer cells.

[Synthesis and structure-activity relationship of cycloberberine as anti-cancer agent].

A series of cycloberberine derivatives were designed, synthesized and evaluated for their anti-cancer activities in vitro. Among these analogs, compounds 6c, 6e and 6g showed strong inhibition on human HepG2 cells. They afforded a potent effect against DOX-resistant MCF-7 breast cells as well. The primary mechanism showed that cell cycle was blocked at G2/M phase of HepG2 cells treated with 6g using flow cytometry assay. It significantly inhibited the activity of DNA Top I at the concentration of 0.1 mg mL-1. Our results provided a basis for the development of this kind of compounds as novel anti-cancer agents.

[Synthesis and structure-activity relationship of N-(2-arylethyl) isoquinoline derivatives as anti-cancer agents].

A series of novel N-(2-arylethyl) isoquinoline derivatives were designed, synthesized and evaluated for their anti-cancer activities. Among these analogs, compound 9a exhibited the potential anti-cancer activities on HepG2 and HCT116 cells with IC50 values of 2.52 and 1.99 microg x mL(-1), respectively. Cell cycle was blocked at S phase of HepG2 cells treated with 9a by flow cytometry detection. Our results provided a basis for the development of a new series of anti-cancer candidates.

Synthesis, structure-activity relationship and biological evaluation of anticancer activity for novel N-substituted sophoridinic acid derivatives.

Sophoridine (1), a natural anticancer drug, has been used in China for decades. A series of novel N-substituted sophoridinic acid derivatives were synthesized and evaluated for their cytotoxicity with 1 as the lead. The structure-activity relationship indicated that introduction of an aliphatic acyl on the nitrogen atom might significantly enhance the anticancer activity. Among the compounds, 6b bearing bromoacetyl side-chain afforded a potential effect against four human tumor cell lines (liver, colon, breast, and lung). The mechanism of action of 6b is to inhibit the activity of DNA topoisomerase I, followed by the S-phase arrest and then cause apoptotic cell death, similar to that of its parent 1. We consider 6b promising for further anticancer investigation.