LY294002 potentiates the anti-cancer effect of oxaliplatin for gastric cancer via death receptor pathway

Survivin (BIRC5): Implications in cancer therapy

Inhibitors of Apoptosis proteins (IAPs) were discovered through experiments aimed at rescuing apoptosis in insects. Classically associated with the inhibition of apoptosis, the IAP member Survivin also regulates cell cycle progression and is an essential component of the Chromosomal Passenger Complex (CPC), responsible for chromosomal segregation. Although undetectable in most adult tissues, Survivin is expressed in Adult Stem Cells (ASCs) and plays a crucial role in their maintenance. Survivin is overexpressed in most cancers, contributing to their clonal expansion. As a result, it has been proposed as a possible anticancer target for nearly two decades. In this discussion, we will explore the rationale behind Survivin as a therapeutic target, focusing on common cancer types such as carcinomas, sarcomas, and leukemias. We will delve into the modulation of Survivin by cancer pro-survival cell signaling, the association between SNPs and tumorigenesis, and its regulation by miRNAs. Finally, we will compare cell growth, clonogenic capacity, and apoptosis, along with different strategies for Survivin inhibition, including gene expression and protein activity modulation.

Prostaglandin F2α synthase promotes oxaliplatin resistance in colorectal cancer through prostaglandin F2α-dependent and F2α-independent mechanism

BACKGROUND

Oxaliplatin (Oxa) is the first-line chemotherapy drug for colorectal cancer (CRC), and Oxa resistance is crucial for treatment failure. Prostaglandin F2α synthase (PGF2α) (PGFS), an enzyme that catalyzes the production of PGF2α, is involved in the proliferation and growth of a variety of tumors. However, the role of PGFS in Oxa resistance in CRC remains unclear.

AIM

To explore the role and related mechanisms of PGFS in mediating Oxa resistance in CRC.

METHODS

The PGFS expression level was examined in 37 pairs of CRC tissues and paracancerous tissues at both the mRNA and protein levels. Overexpression or knockdown of PGFS was performed in CRC cell lines with acquired Oxa resistance (HCT116-OxR and HCT8-OxR) and their parental cell lines (HCT116 and HCT8) to assess its influence on cell proliferation, chemoresistance, apoptosis, and DNA damage. For determination of the underlying mechanisms, CRC cells were examined for platinum-DNA adducts and reactive oxygen species (ROS) levels in the presence of a PGFS inhibitor or its products.

RESULTS

Both the protein and mRNA levels of PGFS were increased in the 37 examined CRC tissues compared to the adjacent normal tissues. Oxa induced PGFS expression in the parental HCT116 and HCT8 cells in a dose-dependent manner. Furthermore, overexpression of PGFS in parental CRC cells significantly attenuated Oxa-induced proliferative suppression, apoptosis, and DNA damage. In contrast, knockdown of PGFS in Oxa-resistant HCT116 and HCT8 cells (HCT116-OxR and HCT8-OxR) accentuated the effect of Oxa treatment in vitro and in vivo. The addition of the PGFS inhibitor indomethacin enhanced the cytotoxicity caused by Oxa. Treatment with the PGFS-catalyzed product PGF2α reversed the effect of PGFS knockdown on Oxa sensitivity. Interestingly, PGFS inhibited the formation of platinum-DNA adducts in a PGF2α-independent manner. PGF2α exerts its protective effect against DNA damage by reducing ROS levels.

CONCLUSION

PGFS promotes resistance to Oxa in CRC via both PGF2α-dependent and PGF2α-independent mechanisms.

Lactate-related metabolic reprogramming and immune regulation in colorectal cancer

Changes in cellular metabolism involving fuel sources are well-known mechanisms of cancer cell differentiation in the context of carcinogenesis. Metabolic reprogramming is regulated by oncogenic signaling and transcriptional networks and has been identified as an essential component of malignant transformation. Hypoxic and acidified tumor microenvironment contributes mainly to the production of glycolytic products known as lactate. Mounting evidence suggests that lactate in the tumor microenvironment of colorectal cancer(CRC) contributes to cancer therapeutic resistance and metastasis. The contents related to the regulatory effects of lactate on metabolism, immune response, and intercellular communication in the tumor microenvironment of CRC are also constantly updated. Here we summarize the latest studies about the pleiotropic effects of lactate in CRC and the clinical value of targeting lactate metabolism as treatment. Different effects of lactate on various immune cell types, microenvironment characteristics, and pathophysiological processes have also emerged. Potential specific therapeutic targeting of CRC lactate metabolism is also discussed. With increased knowledge, effective druggable targets might be identified, with the aim of improving treatment outcomes by reducing chemoresistance.

TRIM29 Reverses Oxaliplatin Resistance of P53 Mutant Colon Cancer Cell

Background

Oxaliplatin is the first-choice chemotherapy method for patients with advanced colon cancer. However, its resistance leads to treatment failure for many patients. In our experiments, we aim to elucidate the associations among TRIM29 protein, mutant P53, and the resistance of colon cancer cells to oxaliplatin.

Methods

HCT116 and HT-29 cells were cultured and transfected with plasmids pIRES2-ZsGreen1-TRIM29-flag. Western blot and real-time qRT-PCR were utilized to examine the protein and mRNA expressions of TRIM29 and other related markers, respectively. MTT assay was utilized to determine the cell growth rate and generate the inhibition curve. Continuous culture in low-concentration oxaliplatin was conducted to construct oxaliplatin-resistant cell lines. The coimmunoprecipitation method and immunofluorescence detection were used to examine the interaction between TRIM29 and mutant P53 protein in HT29 cells.

Results

We successfully transfected pIRES2-ZsGreen1-TRIM29-flag into HCT116 and HT29 cells, which were utilized in the whole experiments. TRIM29 significantly increased the sensitivity of P53 mutant colon cancer cell HT29 to oxaliplatin. The oxaliplatin-resistant model of P53 mutant colon cancer cell HT29 was successfully constructed. TRIM29 physically bound with mutant P53 and retained it in the cytoplasm from the nucleus, which inhibited its transcription function of downstream genes such as MDR1. In addition, TRIM29 successfully reversed the resistance of HT29-OX resistant cell model to oxaliplatin.

Conclusion

In mutant P53 colon cancer cell HT29, TRIM29 greatly increased the sensitivity of HT29 to oxaliplatin and reverse oxaliplatin resistance. The underlying mechanism is TRIM29 may increase the sensitivity of HT29 to oxaliplatin by blocking the transcriptional function of mutant P53, which inhibits the transcription function of its downstream gene such as MDR1.

Omental Tissue-Mediated Tumorigenesis of Gastric Cancer Peritoneal Metastases

The peritoneal cavity, especially the omentum, is a common site for gastric cancer metastasis, representing advanced disease stage and poor prognosis. Here, we studied the effects of omental tissue on gastric cancer tumor progression in vitro and in vivo. Utilizing in vitro models, we found that omental tissue secreted factors increased gastric cancer cellular growth (by 30–67%, P < 0.05), motility (>8-fold, P < 0.05), invasiveness (>7-fold, P < 0.05) and chemoresistance to platinum-based chemotherapeutic agents (>1.2-fold for oxaliplatin and >1.6-fold for cisplatin, P < 0.05). Using a robust proteomic approach, we identified numerous molecules secreted into the omental tissue conditioned medium (CM) which may promote gastric cancer cellular aggressiveness (i.e., IL-6, IL-8, MMP9, FN1, and CXCL-5). Next, an in vivo xenograft mouse model showed an increased human gastric adenocarcinoma tumor volume of cells co-cultured with human omental tissue secreted factors; 1.6 ± 0.55 vs. 0.3 ± 0.19 cm³ (P < 0.001), as well as increased angiogenesis. Finally, exosomes were isolated from human omental tissue CM of gastric cancer patients. These exosomes were taken up by gastric cancer cells enhancing their growth (>8-fold, P < 0.01) and invasiveness (>8-fold, P < 0.001). Proteomic analysis of the content of these exosomes identified several established cancer- related proteins (i.e., IL-6, IL-8, ICAM-1, CCl2, and OSM). Taken together, our findings imply that the omentum play an active role in gastric cancer metastasis. The data also describe specific cytokines that are involved in this cross talk, and that omental tissue- derived exosomes may contribute to these unique cellular interactions with gastric cancer cells. Further studies aimed at understanding the biology of gastric cancer intra peritoneal spread are warranted. Hopefully, such data will enable to develop future novel therapeutic strategies for the treatment of metastatic gastric cancer.

Anticancer effect of resibufogenin on gastric carcinoma cells through the phosphoinositide 3-kinase/protein kinase B/glycogen synthase kinase 3β signaling pathway

The aim of the present study was to investigate the anticancer effect of resibufogenin in gastric carcinoma cells through the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/glycogen synthase kinase 3β (GSK3β) signaling pathway. MGC-803 cells were treated with 0, 1, 2, 4 and 8 µM resibufogenin for 12, 24 and 48 h. Cell viability and apoptosis were measured using an MTT assay and annexin V staining. Caspase-3 and caspase-8 activity were identified using caspase-3 and caspase-8 activity kits and a variety of protein expression [B cell lymphoma (Bcl)-2, Bcl-2-associated X protein (Bax), cyclin D1, cyclin E, PI3K, phosphorylated AKT, phosphorylated GSK3β and β-catenin] were quantified using western blot analysis. It was revealed that resibufogenin effectively inhibited cell proliferation, and induced apoptosis and caspase-3 and caspase-8 activity in MGC-803 cells. Furthermore, treatment with resibufogenin effectively increased Bax/Bcl-2 expression, and suppressed cyclin D1, cyclin E, PI3K, phosphorylated AKT, phosphorylated GSK3β and β-catenin protein expression in MGC-803 cells. These results suggest that the anticancer effect of resibufogenin induces gastric carcinoma cell death through the PI3K/AKT/GSK3β signaling pathway, offering a novel view of the mechanism by which resibufogenin functions as an agent to treat gastric carcinoma.

Targeting the PI3K/Akt/mTOR signalling pathway in Cystic Fibrosis

Deletion of phenylalanine 508 of the cystic fibrosis transmembrane conductance regulator (ΔF508 CFTR) is a major cause of cystic fibrosis (CF), one of the most common inherited childhood diseases. ΔF508 CFTR is a trafficking mutant that is retained in the endoplasmic reticulum (ER) and unable to reach the plasma membrane. Efforts to enhance exit of ΔF508 CFTR from the ER and improve its trafficking are of utmost importance for the development of treatment strategies. Using protein interaction profiling and global bioinformatics analysis we revealed mammalian target of rapamycin (mTOR) signalling components to be associated with ∆F508 CFTR. Our results demonstrated upregulated mTOR activity in ΔF508 CF bronchial epithelial (CFBE41o-) cells. Inhibition of the Phosphatidylinositol 3-kinase/Akt/Mammalian Target of Rapamycin (PI3K/Akt/mTOR) pathway with 6 different inhibitors demonstrated an increase in CFTR stability and expression. Mechanistically, we discovered the most effective inhibitor, MK-2206 exerted a rescue effect by restoring autophagy in ΔF508 CFBE41o- cells. We identified Bcl-2-associated athanogene 3 (BAG3), a regulator of autophagy and aggresome clearance to be a potential mechanistic target of MK-2206. These data further link the CFTR defect to autophagy deficiency and demonstrate the potential of the PI3K/Akt/mTOR pathway for therapeutic targeting in CF.

The Wnt/β-catenin and PI3K/Akt signaling pathways promote EMT in gastric cancer by epigenetic regulation via H3 lysine 27 acetylation

In this study, we investigated the underlying mechanism of the phosphoinositide 3-kinase/Akt- and Wnt/β-catenin-mediated promotion of epithelial-to-mesenchymal transition by epigenetic regulation of histone acetylation in gastric cancer. First, we used immunohistochemistry to detect the expression of phosphorylated Akt, phosphorylated glycogen synthase kinase 3 beta, and β-catenin in gastric cancer tissues and adjacent tissues. In addition, we confirmed that the phosphoinositide 3-kinase/Akt and Wnt/β-catenin signaling pathways were correlated with tumorigenesis, progression, and maintenance of gastric cancer using the phosphoinositide 3-kinase inhibitor LY294002 and an inhibitor of the β-catenin/TCF4 complex, FH535. Epithelial-to-mesenchymal transition-related gene expression was measured by western blotting and quantitative real-time polymerase chain reaction assays. Furthermore, we detected the acetylation of histone H3 lysine 4 and lysine 27 using the FH535 and LY294002 inhibitors at different concentrations for 24 and 48 h. Finally, chromatin immunoprecipitation-quantitative polymerase chain reaction was performed to detect the specific binding of H3K27ac to the promoter of the epithelial-to-mesenchymal transition-related factor, Twist. Taken together, abnormal activation of the phosphoinositide 3-kinase/Akt and Wnt/β-catenin signaling pathway was correlated with the gastric cancer progression and contributed to epithelial-to-mesenchymal transition regulation by controlling histone acetylation.

Suberoylanilide hydroxamic acid enhances the antitumor activity of oxaliplatin by reversing the oxaliplatin‑induced Src activation in gastric cancer cells

Oxaliplatin and the histone deacetylase inhibitor suberoylanilide hydroxamic acid (SAHA), also known as vorinostat, are potent antitumor agents. The aim of this study was to investigate the effect of SAHA on the antitumor efficacy of oxaliplatin in gastric cancer and the interaction between oxaliplatin and SAHA. Cell growth inhibition was evaluated using Cell Counting Kit‑8 and colony formation assays. Xenografts established in nude mice were used to assess tumor growth in vivo. Western blot analysis was used to detect the expression of acetyl‑histone H3, phosphorylated histone H2AX (γH2AX), B‑cell lymphoma 2 (Bcl‑2), cleaved caspase‑3, cleaved poly (ADP‑ribose) polymerase (PARP), phosphorylated- (p-)Src, Src, Akt and p‑Akt in gastric cancer cells. The in vitro growth of SGC‑7901, Hs746T and MKN28 gastric cancer cells was found to be dose‑dependently inhibited by oxaliplatin and SAHA. Furthermore, combined treatment was observed to be more effective in inhibiting cancer cell growth and colony formation than monotherapy. Similar effects were found in the xenografts. A positive interaction was identified between oxaliplatin and SAHA (between‑subject effects of oxaliplatin and SAHA, P<0.001). In addition, combined exposure to oxaliplatin and SAHA increased γH2AX expression and decreased Bcl‑2 expression. The expression of cleaved caspase‑3 and PARP was also increased with combination treatment. Oxaliplatin‑induced Src phosphorylation was detected in gastric cancer cells, as we have previously reported. However, this effect was inhibited by SAHA. The oxaliplatin‑induced Src phosphorylation was not impaired with Akt inhibition. In conclusion, oxaliplatin and SAHA exhibited a positive interaction when used in combination and were found to suppress gastric cancer cell survival and growth. The reversal of oxaliplatin‑induced Src activation may be responsible for this positive interaction.

Targeting the Anti-Apoptotic Protein c-FLIP for Cancer Therapy

Cellular FLICE (FADD-like IL-1beta-converting enzyme)-inhibitory protein (c-FLIP) is a major resistance factor and critical anti-apoptotic regulator that inhibits tumor necrosis factor-alpha (TNF-alpha), Fas-L, and TNF-related apoptosis-inducing ligand (TRAIL)-induced apoptosis as well as chemotherapy-triggered apoptosis in malignant cells. c-FLIP is expressed as long (c-FLIP(L)), short (c-FLIP(S)), and c-FLIP(R) splice variants in human cells. c-FLIP binds to FADD and/or caspase-8 or -10 in a ligand-dependent and-independent fashion, which in turn prevents death-inducing signaling complex (DISC) formation and subsequent activation of the caspase cascade. Moreover, c-FLIP(L) and c-FLIP(S) are known to have multifunctional roles in various signaling pathways, as well as activating and/or upregulating several cytoprotective signaling molecules. Upregulation of c-FLIP has been found in various tumor types, and its downregulation has been shown to restore apoptosis triggered by cytokines and various chemotherapeutic agents. Hence, c-FLIP is an important target for cancer therapy. For example, small interfering RNAs (siRNAs) that specifically knockdown the expression of c-FLIP(L) in diverse human cancer cell lines augmented TRAIL-induced DISC recruitment and increased the efficacy of chemotherapeutic agents, thereby enhancing effector caspase stimulation and apoptosis. Moreover, small molecules causing degradation of c-FLIP as well as decreasing mRNA and protein levels of c-FLIP(L) and c-FLIP(S) splice variants have been found, and efforts are underway to develop other c-FLIP-targeted cancer therapies. This review focuses on (1) the functional role of c-FLIP splice variants in preventing apoptosis and inducing cytokine and drug resistance; (2) the molecular mechanisms that regulate c-FLIP expression; and (3) strategies to inhibit c-FLIP expression and function.

Periostin mediates the increased pro-angiogenic activity of gastric cancer cells under hypoxic conditions

This study was conducted to investigate the biological role of periostin in gastric cancer (GC) under hypoxia. Western blot analysis revealed that along with an upregulation of hypoxia-inducible factor-1alpha, there was a time-dependent induction of periostin in MKN-45 cells under hypoxia (2% O2 ), increasing by eightfold as compared to normoxic cells. Pretreatment with 30 µM PD98059, an inhibitor of ERK1/2, significantly reduced hypoxia-stimulated periostin expression (P < 0.01). Periostin knockdown in MKN-45 cells was achieved by specific small interfering RNA (siRNA). The conditioned medium from periostin siRNA-transfected MKN-45 cells induced significantly less (P < 0.01) endothelial tube formation than control siRNA-transfected cells. Additionally, periostin silencing markedly decreased the mRNA expression and secretion of vascular endothelial growth factor (VEGF) in hypoxic MKN-45 cells. Thus, our data suggest that periostin is a hypoxia-response gene and mediates a cross talk between GC and endothelial cells under hypoxia, partially through regulation of the VEGF expression.

Utilisation of nanoparticle technology in cancer chemoresistance

The implementation of cytotoxic chemotherapeutic drugs in the fight against cancer has played an invariably essential role for minimizing the extent of tumour progression and/or metastases in the patient and thus allowing for longer event free survival periods following chemotherapy. However, such therapeutics are nonspecific and bring with them dose-dependent cumulative adverse effects which can severely exacerbate patient suffering. In addition, the emergence of innate and/or acquired chemoresistance to the exposed cytotoxic agents undoubtedly serves to thwart effective clinical efficacy of chemotherapy in the cancer patient. The advent of nanotechnology has led to the development of a myriad of nanoparticle-based strategies with the specific goal to overcome such therapeutic hurdles in multiple cancer conditions. This paper aims to provide a brief overview and recollection of all the latest advances in the last few years concerning the application of nanoparticle technology to enhance the safe and effective delivery of chemotherapeutic agents to the tumour site, together with providing possible solutions to circumvent cancer chemoresistance in the clinical setting.

Therapeutic effects of combined oxaliplatin and S-1 in older patients with advanced gastric cardiac adenocarcinoma

AIM: To evaluate the effects and safety of combination chemotherapy with oxaliplatin (L-OHP) and S-1 (SOX regimen) in older patients with advanced gastric cardiac adenocarcinoma (GCA).

METHODS: Seventy patients with advanced GCA were classified according to age into an older group (≥ 75 years) and a control group (< 75 years). The SOX regimen was administered to the two groups as follows: S-1 (40 mg/m² po bid) on days 1 to 14 followed by a 7-d off period, plus L-OHP (65 mg/m² iv) for 2 h on days 1 and 8 of a 21-d cycle. This regimen was repeated for four to six cycles. Response and swallow statuses were evaluated after two cycles (6 wk). Effects and toxicity were evaluated four weeks after chemotherapy was completed.

RESULTS: The response rate was 65.6% (21/32) in the older group and 68.4% (26/38) in the control group (χ² = 0.062 and P = 0.804). Improvement in swallowing was 78.1% (25/32) in the older group and 76.3% (29/38) in the control group (χ² = 0.032 and P = 0.857). Efficacy was 68.8% (22/32) in the older group and 65.8% (25/38) in the control group (χ² = 0.069 and P = 0.793). Toxicities were reversible and similar in both groups (P > 0.05).

CONCLUSION: The SOX regimen is an effective, safe and well-tolerated regimen for older patients with advanced GCA.

Significance of expression of AKT, p27Kip1 and cyclin E in gastric carcinoma

AIM: To investigate the expression of AKT, p27^Kip1 and cyclin E proteins in gastric carcinoma and to explore their significance in tumor development and progression.

METHODS: Biopsy and surgical specimens were collected in the Xiangtan City First People's Hospital and Affiliated Nanhua Hospital of University of South China from January 2008 to January 2010, including 14 cases of normal gastric mucosa, 10 cases of atypical hyperplasia, 94 cases of gastric cancer, 49 cases of cancer-adjacent tissue and 35 cases of metastatic cancer. Tissue array technology was used to detect the phosphorylation of AKT and p27^Kip1 proteins and the expression of cyclin E by immunohistochemistry.

RESULTS: Compared to normal gastric mucosa, cancer-adjacent tissue and atypical hyperplasia, the positive rates of AKT phosphorylation and cyclin E overexpression were significantly higher (AKT: 85.1%, 85.7% vs 14.3%, 26.5%, 30.0%; Cyclin E: 85.1%, 82.9% vs 14.3%, 34.7%, 20.0%, all P < 0.01) and that of p27^Kip1 phosphorylation was significantly lower (22.3%, 17.1% vs 71.4%, 44.9%, 40.0%, all P < 0.01) in primary cancer and metastatic carcinoma. Compared to normal gastric mucosa, the positive rate of AKT phosphorylation was significantly higher in atypical hyperplasia (P = 0.26).

CONCLUSION: The phosphorylation of AKT and p27^Kip1 and expression of cyclin E protein are possibly related to the development and progression of gastric carcinoma.