Pemetrexed induces G1 phase arrest and apoptosis through inhibiting Akt activation in human non small lung cancer cell line A549

Phosphodiesterase Inhibition to Sensitize Non-Small-Cell Lung Cancer to Pemetrexed: A Double-Edged Strategy

Phosphosidesterases (PDEs) are key regulators of cyclic nucleotide signaling, controlling many hallmarks of cancer and playing a role in resistance to chemotherapy in non-small-cell lung cancer (NSCLC). We evaluated the anti-tumor activity of the anti-folate agent pemetrexed (PMX), alone or combined with biochemical inhibitors of PDE5, 8, 9, or 10, against squamous and non-squamous NCSLC cells. Genomic alterations to PDE genes (PDEmut) or PDE biochemical inhibition (PDEi) can sensitize NSCLC to PMX in vitro (observed in 50% NSCLC evaluated). The synergistic activity of PDEi with PMX required microdosing of the anti-folate drug. As single agents, none of the PDEis evaluated have anti-tumor activity. PDE biochemical inhibitors, targeting either cAMP or cGMP signaling (or both), resulted in significant cross-modulation of downstream pathways. The use of PDEi may present a new strategy to overcome PMX resistance of PDEwt NSCLC tumors but comes with important caveats, including the use of subtherapeutic PMX doses.

Synergistic anti-tumor effect of bullfrog sialic acid-binding lectin and pemetrexed in malignant mesothelioma

Malignant mesothelioma is an aggressive cancer with limited therapeutic options. Sialic acid-binding lectin isolated from Rana catesbeiana oocytes (cSBL) is a multifunctional protein with anti-cancer activity. The effects of pemetrexed, cisplatin, and cSBL were evaluated in mesothelioma and normal mesothelial cell lines. We evaluated cytotoxicity, apoptosis, caspase-3 cleavage and activation, cell proliferation, cell cycle arrest, and levels of cell cycle proteins in H28 cells treated with pemetrexed, cisplatin, and cSBL alone or in combination. Treatment with cSBL alone was cytotoxic to mesothelioma cells. The anti-cancer effect of cSBL was observed in a broader range of cell lines and exhibited greater cancer cell selectivity than pemetrexed or cisplatin. Combination treatment with pemetrexed + cSBL resulted in greater dose-dependent cytotoxicity than pemetrexed + cisplatin, the standard of care in mesothelioma. The synergistic effect of pemetrexed + cSBL was mediated by the cytostatic effect of pemetrexed and the cytotoxic effect of cSBL. It thus appears that cSBL has therapeutic potential for the treatment of mesothelioma.

Identification of reference genes and miRNAs for qRT-PCR in human esophageal squamous cell carcinoma

It is important to select an appropriate reference gene and miRNA when using quantitative real-time polymerase chain reaction (qRT-PCR) to analyze gene and miRNA expression. However, many commonly used reference genes and miRNAs are not stably expressed and therefore not suitable for normalization or quantification of qRT-PCR data. This study aims to identify appropriate reference genes and miRNAs for use in human esophageal squamous carcinoma qRT-PCR analysis. Using data provided by The Cancer Genome Atlas, we identified DDX5, LAPTM4A, P4HB, RHOA, miR-28-5p, miR-34a-5p, and miR-186-5p as candidate reference genes and miRNAs. We used qRT-PCR to verify the expression levels of these candidates and another seven commonly used reference genes and miRNAs. A set of 50 paired human normal esophageal tissues and squamous cell carcinoma samples were used in the analysis. We then used geNorm and NormFinder to analyze the results. DDX5, LAPTM4A, RHOA, ACTB, RNU48, miR-28-5p, miR-34a-5p, and miR-186-5p were stably expressed, indicating they are suitable for used as references in qRT-PCR analysis of esophageal squamous cell carcinoma. However, expression levels of 18s rRNA, GAPDH, P4HB, 5s rRNA, U6, and RNU6B varied greatly between esophageal normal and squamous cell carcinoma samples, indicating that they are not suitable for use as references in the qRT-PCR analysis of esophageal squamous cell carcinoma.

Establishment of a first-line second-line treatment model for human pulmonary adenocarcinoma

Lung cancer is one of the most prevalent types of cancer in the world. Surgery, chemotherapy and radiotherapy are used clinically as treatments for numerous cancers. Due to the appearance of drug resistance, the remission rate is limited to 40–50%. Docetaxel and pemetrexed are two drugs commonly used, and their effects in single-phase cell culture are well known. From the pharmacological point of view, it appears rational to hypothesize that sequential therapy effects can show better outcomes compared with traditional single-phase experiments. Considering this, the present study aimed to establish a first-line second-line adenocarcinoma treatment model, using the combination of cisplatin with docetaxel or pemetrexed in vitro in different sequential therapy timings. To test this, the human lung cancer A549 cell line was used. The inhibitory effect was determined by adding docetaxel following treatment with cisplatin and pemetrexed (Pem-Doc group) and comparing this with a group in which pemetrexed was added subsequent to treatment with cisplatin and docetaxel (Doc-Pem group). Additionally, the differences in the gene and protein expression levels of excision repair cross-completion gene 1 (ERCC1), a gene that promotes drug resistance to cisplatin, were compared between the two groups. The present results showed that the inhibitory effect of cell proliferation in the Pem-Doc group was increased compared with that of Doc-Pem group, while the gene expression and protein levels of ERCC1 in the Pem-Doc group were decreased compared with those of Doc-Pem group. The Pem-Doc treatment plan is more effective in inhibiting cell proliferation and in lowering the expression of the ERCC1 gene. Therefore, Pem-Doc may be a more effective adenocarcinoma treatment.

Novel recombinant protein FlaA N/C increases tumor radiosensitivity via NF-κB signaling in murine breast cancer cells

The recombinant protein flagellin A (FlaA) N/C, derived from the flagellin protein of Legionella pneumophila, has been shown to increase the expression of cytoprotective cytokines, activate the nuclear factor-κB (NF-κB) signaling pathway, and increase the survival of mice following total body irradiation. Determi ning whether FlaA N/C has a sensitizing effect on tumor radiation or a direct tumoricidal effect is critical for its application as an effective radiation protection agent. The present study investigated the molecular mechanism underlying the tumor radiosensitivity of FlaA N/C. FlaA N/C was found to increase tumor apoptosis and autophagy, regulate the cell cycle and increase radiosensitivity in 4T1 tumor cells. Furthermore, FlaA N/C was found to promote radiosensitivity by activating NF-κB signaling. Finally, the present study analyzed FlaA N/C-enhanced radiosensitivity in animal models, and FlaA N/C was found to significantly prolong the survival period of mice after total body radiation. This indicates that FlaA N/C might be a novel radiation sensitizer in tumor radiation therapy.

Treatment with a Small Synthetic Compound, KMU-193, induces Apoptosis in A549 Human Lung Carcinoma Cells through p53 Up-Regulation

Despite recent advances in therapeutic strategies for lung cancer, mortality still is increasing. In the present study, we investigated the anti-cancer effects of KMU-193, 2-(4-Ethoxy-phenyl)-N-{5-[2-fluoro-4-(4-methyl- piperazine-1-carbonyl)-phenylamino]-1H-indazol-3-yl}-acetamide in a human non-small cell lung cancer cell line A549. KMU-193 strongly inhibited the proliferation of A549 cells, but it did not have anti-proliferative effect in other types of cancer cell lines. KMU-193 further induced apoptosis in association with activation of caspase-3 and cleavage of PLC-γ1. However, KMU-193 had no apoptotic effect in untransformed cells such as TMCK-1 and BEAS-2B. Interestingly, pretreatment with z-VAD-fmk, a pan-caspase inhibitor, strongly abrogated KMU- 193-induced apoptosis. KMU-193 treatment enhanced the expression levels of p53 and PUMA. Importantly, p53 siRNA transfection attenuated KMU-193-induced apoptosis. Collectively, these results for the first time demonstrate that KMU-193 has strong apoptotic effects on A549 cells and these are largely mediated through caspase-3- and p53-dependent pathways.