Validation of routine mycoplasma testing by PCR

NLRP6, decreased in gastric cancer, suppresses tumorigenicity of gastric cancer cells

Background

Helicobacter pylori (H. pylori) infection has been regarded as a main risk factor for gastric cancer. Nod-like receptor pyrin domain-containing protein 6 (NLRP6), a component of inflammasome, has been linked to colorectal tumorigenesis. Here, we aimed to evaluate NLRP6 expression profile and functions in gastric cancer.

Materials and methods

We examined NLRP6 expression in gastric cancer and adjacent normal gastric tissues. The biological functions and mechanism of NLRP6 overexpression in gastric cancer cells were investigated.

Results

Downregulated NLRP6 expression in human gastric cancer significantly correlated with H. pylori infection, tumor size, TNM stage, lymph node metastasis, and overall survival. NLRP6 overexpression in gastric cancer cells led to a significant decrease in cell proliferation, migration, and invasion, as well as a notable increase in cell apoptosis, whereas NLRP6 knockdown had opposing effects. In addition, NLRP6 overexpression significantly repressed STAT3 phosphorylation and the transcription of its target genes, Bcl-2 and MMP-2. Moreover, forkhead box O3 (FOXO3), a transcription factor regulated by H. pylori, was demonstrated as an upstream regulator of NLRP6 transcription.

Conclusion

Our study may provide insight into the understanding of NLRP6 as a tumor suppressor and implicate the potential application of NLRP6 for gastric cancer treatment.

tRF-Leu-CAG promotes cell proliferation and cell cycle in non-small cell lung cancer

tRNA-derived RNA fragments (tRFs), non-coding single-stranded RNAs with 14-35 nt in length, were found to play important roles in gene regulation, even in carcinogenesis. In this study, we investigated the expression of tRF-Leu-CAG in human non-small cell lung cancer (NSCLC) and its function in the cell proliferation and cell cycle of NSCLC. The expression level of tRF-Leu-CAG was detected in NSCLC tissues, cell lines, and sera. tRF-Leu-CAG RNA levels were higher in NSCLC tumor tissues than in normal tissues, and also upregulated in NSCLC cell lines. A significant relationship was observed between stage progression and tRF-Leu-CAG in NSCLC sera. We found that in H1299 cells, inhibition of tRF-Leu-CAG suppressed cell proliferation and impeded cell cycle. AURKA was also repressed with the knockdown of tRF-Leu-CAG. Thus, our study revealed that tRF-Leu-CAG may be involved in regulating AURKA and could be a new diagnostic marker and potential therapeutic target in NSCLC.

The trophoblast cell surface antigen 2 and miR-125b axis in urothelial bladder cancer

Human trophoblast cell surface antigen 2 (Trop-2) is a 40-kDa transmembrane glycoprotein that was first identified as a marker of human trophoblast cells. Trop-2 acts on cell proliferation, adhesion, and migration by activating a number of intracellular signalling pathways. Elevated Trop-2 expression has been demonstrated in several types of cancer and correlated with aggressiveness and poor prognosis. Since no data are available on Trop-2 in bladder cancer (BC), the purpose of the study was to determine its levels in tissue specimens from normal individuals and patients with BC at different stages. Moreover, since according to recent evidence Trop-2 is a miR-125b target, miR-125b expression was also assessed in tissue specimens. Finally, the effect of the Trop-2/miR-125b axis on the proliferation and migration of BC cells was evaluated in vitro.

The Trop-2/miR-125b axis was seen to be differentially expressed in normal urothelium, non-invasive BC and invasive BC tissue. Significant miR-125b down-regulation was associated with a significant increase in Trop-2 protein levels in BC tissue and correlated with disease severity. In vitro analysis confirmed the role of miR-125b in down-modulation of Trop-2 protein levels and showed that Trop-2/miR-125b axis affects cellular proliferation in bladder tissue.

In conclusion, our findings highlight a role for the Trop-2/miR-125b axis in BC progression and suggest Trop-2 and miR-125b as diagnostic/prognostic marker candidates as well as druggable targets for innovative therapeutic approaches.

Twist2 promotes kidney cancer cell proliferation and invasion by regulating ITGA6 and CD44 expression in the ECM-receptor interaction pathway

Twist2 is a member of the basic helix-loop-helix (bHLH) family and plays a critical role in tumorigenesis. Growing evidence has proven that Twist2 is involved in tumor progression; however, the role of Twist2 in human kidney cancer and its underlying mechanisms remain unclear. Real-time polymerase chain reaction and Western blot analysis were used to detect the expression of Twist2 in kidney cancer cells and tissues. Cell proliferation, cell cycle, apoptosis, migration, and invasion assay were analyzed using the Cell Count Kit-8, flow cytometry, wound healing, and Transwell analysis, respectively. In this study, we showed that Twist2 was upregulated in human kidney cancer tissues compared with normal kidney tissues. Twist2 promoted cell proliferation, inhibited cell apoptosis, and augmented cell migration and invasion in human kidney-cancer-derived cells in vitro. Twist2 also promoted tumor growth in vivo. Moreover, we found that the knockdown of Twist2 decreased the levels of ITGA6 and CD44 expression. This result indicates that Twist2 may promote migration and invasion of kidney cancer cells by regulating ITGA6 and CD44 expression. Therefore, our data demonstrated that Twist2 is involved in kidney cancer progression. The identification of the role of Twist2 in the migration and invasion of kidney cancer provides a potential appropriate treatment for human kidney cancer.

Trop-2 Induces Tumor Growth Through AKT and Determines Sensitivity to AKT Inhibitors

PURPOSE

Inhibition of AKT is a key target area for personalized cancer medicine. However, predictive markers of response to AKT inhibitors are lacking. Correspondingly, the AKT-dependent chain of command for tumor growth, which will mediate AKT-dependent therapeutic responses, remains unclear.

EXPERIMENTAL DESIGN

Proteomic profiling was utilized to identify nodal hubs of the Trop-2 cancer growth-driving network. Kinase-specific inhibitors were used to dissect Trop-2-dependent from Trop-2-independent pathways. In vitro assays, in vivo preclinical models, and case series of primary human breast cancers were utilized to define the mechanisms of Trop-2-driven growth and the mode of action of Trop-2-predicted AKT inhibitors.

RESULTS

Trop-2 and AKT expression was shown to be tightly coordinated in human breast cancers, with virtual overlap with AKT activation profiles at T308 and S473, consistent with functional interaction in vivo AKT allosteric inhibitors were shown to only block the growth of Trop-2-expressing tumor cells, both in vitro and in preclinical models, being ineffective on Trop-2-null cells. Consistently, AKT-targeted siRNA only impacted on Trop-2-expressing cells. Lentiviral downregulation of endogenous Trop-2 abolished tumor response to AKT blockade, indicating Trop-2 as a mandatory activator of AKT.

CONCLUSIONS

Our findings indicate that the expression of Trop-2 is a stringent predictor of tumor response to AKT inhibitors. They also support the identification of target-activatory pathways, as efficient predictors of response in precision cancer therapy. Clin Cancer Res; 22(16); 4197-205. ©2016 AACR.

Antitumor activity of a novel oncrasin analogue is mediated by JNK activation and STAT3 inhibition

Background

To optimize the antitumor activity of oncrasin-1, a small molecule identified through synthetic lethality screening on isogenic K-Ras mutant tumor cells, we developed several analogues and determined their antitumor activities. Here we investigated in vitro and in vivo antitumor activity of NSC-743380 (1-[(3-chlorophenyl) methyl]-1H-indole-3-methanol, oncrasin-72), one of most potent analogues of oncrasin-1.

Methodology and Principal Findings

In vitro antitumor activity was determined in NCI-60 cancer cell line panel using cell viability assay. In vivo antitumor activity was determined in parallel with NSC-741909 (oncrasin-60) in xenograft tumors established in nude mice from A498, a human renal cancer cell line. Changes in gene expression levels and signaling pathway activities upon treatment with NSC-743380 were analyzed in breast and renal cancer cells by Western blot analysis. Apoptosis was demonstrated by Western blot analysis and flow cytometric analysis. NSC-743380 is highly active against a subset of cancer cell lines derived from human lung, colon, ovary, kidney, and breast cancers. The 50% growth-inhibitory concentration (GI₅₀) for eight of the most sensitive cell lines was ≤10 nM. In vivo study showed that NSC-743380 has a better safety profile and greater antitumor activity than NSC-741909. Treatment with NSC-743380 caused complete regression of A498 xenograft tumors in nude mice at the tested doses ranging from 67 mg/kg to 150 mg/kg. Mechanistic characterization revealed that NSC-743380 suppressed the phosphorylation of C-terminal domain of RNA polymerase II, induced JNK activation, inhibited JAK2/STAT3 phosphorylation and suppressed cyclin D1 expression in sensitive human cancer cells. Blocking JNK activation or overexpression of constitutively active STAT3 partially blocked NSC-743380-induced antitumor activity.

Conclusions

NSC-743380 induces antitumor activity through modulation of functions in multiple cancer related pathways and could be a potential anticancer agent for some solid tumors.

Primary cultured fibroblasts derived from patients with chronic wounds: a methodology to produce human cell lines and test putative growth factor therapy such as GMCSF

BACKGROUND

Multiple physiologic impairments are responsible for chronic wounds. A cell line grown which retains its phenotype from patient wounds would provide means of testing new therapies. Clinical information on patients from whom cells were grown can provide insights into mechanisms of specific disease such as diabetes or biological processes such as aging. The objective of this study was 1) To culture human cells derived from patients with chronic wounds and to test the effects of putative therapies, Granulocyte-Macrophage Colony Stimulating Factor (GM-CSF) on these cells. 2) To describe a methodology to create fibroblast cell lines from patients with chronic wounds.

METHODS

Patient biopsies were obtained from 3 distinct locations on venous ulcers. Fibroblasts derived from different wound locations were tested for their migration capacities without stimulators and in response to GM-CSF. Another portion of the patient biopsy was used to develop primary fibroblast cultures after rigorous passage and antimicrobial testing.

RESULTS

Fibroblasts from the non-healing edge had almost no migration capacity, wound base fibroblasts were intermediate, and fibroblasts derived from the healing edge had a capacity to migrate similar to healthy, normal, primary dermal fibroblasts. Non-healing edge fibroblasts did not respond to GM-CSF. Six fibroblast cell lines are currently available at the National Institute on Aging (NIA) Cell Repository.

CONCLUSION

We conclude that primary cells from chronic ulcers can be established in culture and that they maintain their in vivo phenotype. These cells can be utilized for evaluating the effects of wound healing stimulators in vitro.

Microbiological control in stem cell banks: approaches to standardisation

The transplant of cells of human origin is an increasingly complex sector of medicine which entails great opportunities for the treatment of a range of diseases. Stem cell banks should assure the quality, traceability and safety of cultures for transplantation and must implement an effective programme to prevent contamination of the final product. In donors, the presence of infectious micro-organisms, like human immunodeficiency virus, hepatitis B virus, hepatitis C virus and human T cell lymphotrophic virus, should be evaluated in addition to the possibility of other new infectious agents (e.g. transmissible spongiform encephalopathies and severe acute respiratory syndrome). The introduction of the nucleic acid amplification can avoid the window period of these viral infections. Contamination from the laboratory environment can be achieved by routine screening for bacteria, fungi, yeast and mycoplasma by European pharmacopoeia tests. Fastidious micro-organisms, and an adventitious or endogenous virus, is a well-known fact that will also have to be considered for processes involving in vitro culture of stem cells. It is also a standard part of current good practice in stem cell banks to carry out routine environmental microbiological monitoring of the cleanrooms where the cell cultures and their products are prepared. The risk of viral contamination from products of animal origin, like bovine serum and mouse fibroblasts as a “feeder layer” for the development of embryonic cell lines, should also be considered. Stem cell lines should be tested for prion particles and a virus of animal origin that assure an acceptable quality.

Development of a PCR method for mycoplasma testing of Chinese hamster ovary cell cultures used in the manufacture of recombinant therapeutic proteins

Chinese hamster ovary (CHO) cell cultures used to produce biopharmaceuticals are tested for mycoplasma contamination as part of the ensurance of a safe and pure product. The current U.S. Food and Drug Administration (FDA) regulatory guideline recommends using two procedures: broth/agar cultures and DNA staining of indicator cell cultures. Although these culture methods are relatively sensitive to most species, theoretically capable of detecting as few as 1-10 cfu/ml of most species, the overall procedure is lengthy (28 d), costly and less sensitive to noncultivable species. The detection of mycoplasma using the polymerase chain reaction (PCR) method has been considered an alternative method because it is relatively fast (1-2 d), inexpensive, and independent of culture conditions, however, limitations in sensitivity (limit of detection >/=1000 cfu/ml) and the risk of false positive and false negative results have prevented PCR from replacing the traditional culture methods in the industrial setting. In this report, we describe a new PCR assay for mycoplasma detection that appears to resolve these issues while being sufficiently simple and inexpensive for routine use. This assay applies readily available techniques in DNA extraction together with a modified single-step PCR using a previously characterized primer pair that is homologous to a broad spectrum of mycoplasma species known to infect mammalian cell cultures. Analysis is made easy by the detection of only a single amplification product within a narrow size range, 438-470 bp. A high sensitivity and specificity for mycoplasma detection in CHO cell production cultures is made possible through the combination of three key techniques: 8-methoxypsoralen and UV light treatment to decontaminate PCR reagents of DNA; hot-start Taq DNA polymerase to reduce nonspecific priming events; and touchdown- (TD-) PCR to increase sensitivity while also reducing nonspecific priming events. In extracts of mycoplasma DNA, the limit of detection for eight different mycoplasma species is 10 genomic copies. In CHO cell production cultures containing gentamicin, the limit of detection for a model organism, gentamicin-resistant M. hyorhinis, is 1 cfu/ml. The sensitivity and specificity of this PCR assay for mycoplasma detection in CHO cell production cultures appear similar to the currently used culture methods and thus should be considered as an alternative method by the biopharmaceutical industry.

Comparative PCR analysis for detection of mycoplasma infections in continuous cell lines

Mycoplasma contamination of cell lines is one of the major problems in cell culturing. About 15-35% of all cell lines are infected with a limited number of mycoplasma species of predominantly human, swine, or bovine origin. We examined the mycoplasma contamination status in 495 cell cultures by polymerase chain reaction (PCR) assay, microbiological culture method, and deoxyribonucleic acid-ribonucleic acid (DNA-RNA) hybridization, and in 103 cell cultures by PCR and DNA-RNA hybridization, in order to determine the sensitivity and specificity of the PCR assay in routine cell culture. For those two cohorts, results for the three or two assays were concordant in 92 and 91% of the cases, respectively. The sensitivity (detection of true positives) of this PCR detection assay was 86%, and the specificity (detection of true negatives) was 93%, with positive and negative predictive values (probability of correct results) of 73 and 97%, respectively. PCR defined the mycoplasma status with 92% accuracy (detection of true positives and true negatives). The mycoplasma contaminants were speciated by analyzing the PCR amplification fragment using several restriction enzymes. Most of the cultures (47%) were infected with Mycoplasma fermentans, followed by M. hyorhinis (19%), M. orale (10%), M. arginini (9%), Acholeplasma laidlawii (6%), and M. hominis (3%). To sum up, PCR represents a sensitive, specific, accurate, inexpensive, and quick mycoplasma detection assay that is suitable for the routine screening of cell cultures.

Comparative PCR analysis for detection of mycoplasma infections in continuous cell lines

Mycoplasma contamination of cell lines is one of the major problems in cell culturing. About 15-35% of all cell lines are infected with a limited number of mycoplasma species of predominantly human, swine, or bovine origin. We examined the mycoplasma contamination status in 495 cell cultures by polymerase chain reaction (PCR) assay, microbiological culture method, and deoxyribonucleic acid-ribonucleic acid (DNA-RNA) hybridization, and in 103 cell cultures by PCR and DNA-RNA hybridization, in order to determine the sensitivity and specificity of the PCR assay in routine cell culture. For those two cohorts, results for the three or two assays were concordant in 92 and 91% of the cases, respectively. The sensitivity (detection of true positives) of this PCR detection assay was 86%, and the specificity (detection of true negatives) was 93%, with positive and negative predictive values (probability of correct results) of 73 and 97%, respectively. PCR defined the mycoplasma status with 92% accuracy (detection of true positives and true negatives). The mycoplasma contaminants were speciated by analyzing the PCR amplification fragment using several restriction enzymes. Most of the cultures (47%) were infected with Mycoplasma fermentans, followed by M. hyorhinis (19%), M. orale (10%), M. arginini (9%), Acholeplasma laidlawii (6%), and M. hominis (3%). To sum up, PCR represents a sensitive, specific, accurate, inexpensive, and quick mycoplasma detection assay that is suitable for the routine screening of cell cultures.