Activated Akt Prevents Antitumor Activity of Gefitinib in Renal Cancer Cells

PI3K/Akt signaling in urological cancers: Tumorigenesis function, therapeutic potential, and therapy response regulation

In addition to environmental conditions, lifestyle factors, and chemical exposure, aberrant gene expression and mutations involve in the beginning and development of urological tumors. Even in Western nations, urological malignancies are among the top causes of patient death, and their prevalence appears to be gender dependent. The prognosis for individuals with urological malignancies remains dismal and unfavorable due to the ineffectiveness of conventional treatment methods. PI3K/Akt is a popular biochemical mechanism that is activated in tumor cells as a result of PTEN loss. PI3K/Akt escalates growth and metastasis. Moreover, due to the increase in tumor cell viability caused by PI3K/Akt activation, cancer cells may acquire resistance to treatment. This review article examines the function of PI3K/Akt in major urological tumors including bladder, prostate, and renal tumors. In prostate, bladder, and kidney tumors, the level of PI3K and Akt are notably elevated. In addition, the activation of PI3K/Akt enhances the levels of Bcl-2 and XIAP, hence increasing the tumor cell survival rate. PI3K/Akt ] upregulates EMT pathways and matrix metalloproteinase expression to increase urological cancer metastasis. Furthermore, stimulation of PI3K/Akt results in drug- and radio-resistant cancers, but its suppression by anti-tumor drugs impedes the tumorigenesis.

Identifying Gene Signatures for Cancer Drug Repositioning Based on Sample Clustering

Drug repositioning is an important approach for drug discovery. Computational drug repositioning approaches typically use a gene signature to represent a particular disease and connect the gene signature with drug perturbation profiles. Although disease samples, especially from cancer, may be heterogeneous, most existing methods consider them as a homogeneous set to identify differentially expressed genes (DEGs)for further determining a gene signature. As a result, some genes that should be in a gene signature may be averaged off. In this study, we propose a new framework to identify gene signatures for cancer drug repositioning based on sample clustering (GS4CDRSC). GS4CDRSC first groups samples into several clusters based on their gene expression profiles. Second, an existing method is applied to the samples in each cluster for generating a list of DEGs. Then a weighting approach is used to identify an intergrated gene signature from all the lists of DEGs. The integrated gene signature is used to connect with drug perturbation profiles in the Connectivity Map (CMap)database to generate a list of drug candidates. GS4CDRSC has been tested with several cancer datasets and existing methods. The computational results show that GS4CDRSC outperforms those methods without the sample clustering and weighting approaches in terms of both number and rate of predicted known drugs for specific cancers.

Antitumor functions and mechanisms of nitidine chloride in human cancers

Nitidine chloride (NC), a quaternary ammonium alkaloid, exhibits multiple biological activities, including antimalarial, antifungal, and antiangiogenesis. Recently, NC has been characterized to perform antitumor activity in a variety of malignancies. NC has been identified to suppress cell proliferation, stimulate apoptosis, and induce cell cycle arrest, retard migration, invasion and metastasis. Moreover, NC is reported to sensitize cancer cells to chemotherapeutic drugs. In this review article, we describe the functions of NC in human cancers and discuss the molecular insight into NC-involved antitumor feature. This review article will stimulate the deeper investigation for using NC as a potent agent for the management of cancer patients.

Docosahexaenoic acid inhibits the phosphorylation of STAT3 and the growth and invasion of renal cancer cells

Docosahexaenoic acid (DHA) has a variety of anti-tumor activities. The present study examined the anti-tumor activity of DHA in renal cancer cells and its underlying mechanisms of action. The effects of DHA on the viability and proliferation of the human renal cancer cell lines Caki-1 and 786-O were examined by an MTS assay and cell counting. In addition, cell cycle distribution and cell apoptosis were analyzed by flow cytometry and Annexin V staining, and modulation of cell mobility and invasiveness was assessed by wound healing and Matrigel invasion assays. Effects of DHA on intracellular signaling pathways were also analyzed by western blotting. It was observed that DHA significantly reduced the viability and proliferation of Caki-1 and 786-O cells (P<0.01). Specifically, there were increases in the sub-G1 and G2/M cell populations, as well as the percentages of cells exhibiting Annexin-positive and propidium-iodide-negative staining. In addition, the covered area in a wound and the number of cells invading through a Matrigel chamber decreased when Caki-1 or 786-O cells were treated with DHA. Phosphorylation of epidermal growth factor receptor was also upregulated following DHA treatment, while phosphorylation of signal transducer and activator of transcription 3 and Akt was downregulated. Collectively, these data suggest that DHA may be useful in the treatment of renal cell carcinoma.

Sphingosine kinase-1 activation causes acquired resistance against Sunitinib in renal cell carcinoma cells

Multi-target tyrosine kinase inhibitor Sunitinib has been widely used in cancer treatment, including metastatic renal cell carcinoma. However, most patients who initially benefit from Sunitinib develop resistance with extended usage of Sunitinib, which is referred to as "acquired resistance". The molecular mechanisms contributing to this acquired resistance remain poorly understood. In this present study, we established Sunitinib-resistant cell lines from human renal cell lines (786-O, A498, ACHN and CAKI1) by continuous treatment with Sunitinib to explore the molecular mechanism leading to Sunitinib resistance. We found that PDGFR-β expression in cell seems to be a protective factor against Sunitinib resistance formation. In addition, we found that both SK1 and ERK were activated in Sunitinib-resistance cell lines and SK1 and ERK inhibitors could resensitize Sunitinib-resistant cell lines. In conclusion, our observations suggest that SK1 and ERK activation is a feature of resistant cell lines, which serves as an alternative pathway evading anti-tumor activity of Sunitinib.

Nitidine chloride inhibits renal cancer cell metastasis via suppressing AKT signaling pathway

Nitidine Chloride (NC) has been shown to have anti-cancer effects on various tumors. However, whether NC could exert anti-metastasis activity in renal cancer cells and the underlying mechanisms have not been elucidated. In this work, our data demonstrated the anti-metastasis effects of NC on renal cancer cells in vitro. With scratch assay and transwell assays, we found that NC potently suppressed the migration and invasion of 786-O and A498 cells. Mechanistically, we presented that NC significantly decreased phosphorylation of AKT, accompanied by down-regulation of MMP-2 and MMP-9. Furthermore, a specific AKT inhibitor, LY294002, could enhance the anti-metastasis effects of NC, which indicated that NC suppressed metastasis of renal cancer cells partly via inhibition of AKT activity. Taken together, our results imply that NC can be developed as a potential anti-metastasis agent to renal cancer.

Inhibition of fatty-acid synthase suppresses P-AKT and induces apoptosis in bladder cancer

OBJECTIVE

To investigate the role of fatty acid synthase (FASN) in bladder transitional cell carcinoma (BTCC).

METHODS

FASN expression was investigated in non-muscle-invasive BTCC tissue specimens by immunohistochemistry and BTCC cell lines by Western blot. After treatment with FASN-siRNA or FASN inhibitor cerulenin (Cer), the proliferation and apoptosis of BTCC cell lines 5637 and 253 J were determined by cell counting Kit-8 (CCK8) assay and flow cytometry respectively. The expression of p-AKT, cyclin D1 (CCND1), and apoptosis-related proteins were detected by Western blot.

RESULTS

High levels of FASN expression were observed in 59% (32/54) of non-muscle-invasive BTCC tissue specimens, and FASN expression was associated with histologic grade (P < .05) and recurrence (P < .05). FASN expression was high in 6 BTCC cell lines. FASN inhibitor Cer and FASN-siRNA produced the increased apoptosis and decreased proliferation of bladder cancer cells, and caused inactivity of AKT and downregulation of CCND1. Furthermore, treatment of BTCC cell lines with Cer resulted in apoptosis via the caspase-dependent pathway involving inactivation of antiapoptotic bcl-2 protein.

CONCLUSION

Our data suggest that FASN plays an important role in BTCC development. Targeting FASN may be a new therapeutic strategy for BTCC.

A phase I dose-escalation and pharmacokinetic study of enzastaurin and erlotinib in patients with advanced solid tumors

Purpose

Enzastaurin, an oral serine/threonine kinase inhibitor, targets the protein kinase C and AKT pathways with anti-tumor and anti-angiogenic effects. Erlotinib, an oral epidermal growth factor receptor (EGFR) inhibitor, has activity in solid tumors. Based on the promising combination of EGFR inhibitors and anti-angiogenic agents, this phase I trial was initiated.

Methods

This single-institution, open-label, non-randomized trial used a standard 3 + 3 dose-escalation model in patients with advanced solid malignancies including non-small-cell lung cancer (NSCLC). Two dose levels of enzastaurin (with loading doses) were explored: 250 mg daily and 500 mg daily. Erlotinib was given at 150 mg daily.

Results

Sixteen patients were enrolled in this study (median age, 64 years). Most patients were heavily pre-treated, female, and Caucasian and had NSCLC. The highest dose of enzastaurin, 500 mg daily, was tolerated with no unexpected adverse events and no alteration in the pharmacokinetics of either drug at this dose level. The mean clearance was 5.75 L/h for erlotinib and 53.8 L/h for enzastaurin. The most common possibly drug-related grade 3–4 adverse events included diarrhea (25.0%), neurologic symptoms (18.8%), and vomiting (18.8%). Activity was noted, with a partial response in one patient and prolonged disease stability for >12 cycles in three patients.

Conclusion

The combination of enzastaurin 500 mg daily and erlotinib 150 mg daily is well tolerated and does not alter the pharmacokinetics of the individual drugs, with clinical activity seen. A phase II trial of this combination has been initiated in patients with advanced-stage NSCLC.

Enhanced effects by 4-phenylbutyrate in combination with RTK inhibitors on proliferation in brain tumor cell models

We have investigated in vitro effects of anticancer therapy with the histone deacetylase inhibitor (HDACi) 4-phenylbutyrate (4-PB) combined with receptor tyrosine kinase inhibitors (RTKi) gefitinib or vandetanib on the survival of glioblastoma (U343MGa) and medulloblastoma (D324Med) cells. In comparison with individual effects of these drugs, combined treatment with gefitinib/4-PB or vandetanib/4-PB resulted in enhanced cell killing and reduced clonogenic survival in both cell lines. Our results suggest that combined treatment using HDACi and RTKi may beneficially affect the outcome of cancer therapy.

A phase II trial of gefitinib and pegylated IFNα in previously treated renal cell carcinoma

BACKGROUND

This study was conducted to evaluate the efficacy of the epidermal growth factor receptor tyrosine kinase inhibitor gefitinib with pegylated-IFNα (PEG-IFNα) in patients with advanced renal cell carcinoma.

METHODS

Progression-free survival (PFS) rate at 6 months >50% was considered promising for further evaluation. Patients with unresectable or metastatic disease, unlimited prior therapies, and adequate performance status and end-organ function were eligible. PEG-IFNα was dosed subcutaneously once weekly (initially 6 μg/kg/week, later reduced to 4 μg/kg/week) for 12 weeks. Gefitinib was given 250 mg orally once daily until progression or intolerance.

RESULTS

Twenty-one patients were accrued. Fourteen patients had a prior nephrectomy, and twelve had prior systemic therapy. The 6-month PFS was 29% (95%CI 15-56%). Best responses by RECIST criteria: complete, partial (1, plus 3 unconfirmed) stable (Uhlman et al. Clin Cancer Res 1:913-920, 1995), and progression (Sirotnak et al. Clin Cancer Res 6:4885-4892, 2000). Response duration: complete response (35+ months) and partial response (2, 3, 3, 37 months). Median PFS and overall survival were 5.3 (95%CI 3-10.1) and 13.6 (95%CI 10.3-NA) months, respectively. Most common toxicities included myelosuppression, rash, and nausea.

CONCLUSIONS

Although generally well tolerated, gefitinib plus PEG-IFNα did not meet the pre-specified 6-month PFS rate >50%. Further evaluation of similar regimens would require appropriate molecular selection of subjects most likely to benefit. Thus, preclinical studies to determine candidate predictive markers for this combination are warranted.