Novel triple‑positive markers identified in human non‑small cell lung cancer cell line with chemotherapy-resistant and putative cancer stem cell characteristics

Through the specific identification and direct targeting of cancer stem cells (CSCs), it is believed that a better treatment efficacy of cancer may be achieved. Hence, the present study aimed to identify a CSC subpopulation from adenocarcinoma cells (A549) as a model of non-small cell lung cancer (NSCLC). Initially, we sorted two subpopulations known as the triple-positive (EpCAM⁺/CD166⁺/CD44⁺) and triple-negative (EpCAM⁻/CD166⁻/CD44⁻) subpopulation using fluorescence-activated cell sorting (FACS). Sorted cells were subsequently evaluated for proliferation and chemotherapy-resistance using a viability assay and were further characterized for their clonal heterogeneity, self-renewal characteristics, cellular migration, alkaline dehydrogenase (ALDH) activity and the expression of stemness-related genes. According to our findings the triple-positive subpopulation revealed significantly higher (P<0.01) proliferation activity, exhibited better clonogenicity, was mostly comprised of holoclones and had markedly bigger (P<0.001) spheroid formation indicating a better self-renewal capacity. A relatively higher resistance to both 5-fluouracil and cisplatin with 80% expression of ALDH was observed in the triple-positive subpopulation, compared to only 67% detected in the triple-negative subpopulation indicated that high ALDH activity contributed to greater chemotherapy-resistance characteristics. Higher percentage of migrated cells was observed in the triple-positive subpopulation with 56% cellular migration being detected, compared to only 19% in the triple-negative subpopulation on day 2. This was similarly observed on day 3 in the triple-positive subpopulation with 36% higher cellular migration compared to the triple-negative subpopulation. Consistently, elevated levels of the stem cell genes such as REX1 and SSEA4 were also found in the triple-positive subpopulation indicating that the subpopulation displayed a strong characteristic of pluripotency. In conclusion, our study revealed that the triple-positive subpopulation demonstrated similar characteristics to CSCs compared to the triple-negative subpopulation. It also confirmed the feasibility of using the triple-positive (EpCAM⁺/CD166⁺/CD44⁺) marker as a novel candidate marker that may lead to the development of novel therapies targeting CSCs of NSCLC.

Transplantation of human bone marrow mesenchymal stromal cells reduces liver fibrosis more effectively than Wharton's jelly mesenchymal stromal cells

Background

Mesenchymal stromal cells (MSCs) from various tissues have shown moderate therapeutic efficacy in reversing liver fibrosis in preclinical models. Here, we compared the relative therapeutic potential of pooled, adult human bone marrow (BM)- and neonatal Wharton’s jelly (WJ)-derived MSCs to treat CCl₄-induced liver fibrosis in rats.

Methods

Sprague-Dawley rats were injected with CCl₄ for 8 weeks to induce irreversible liver fibrosis. Ex-vivo expanded, pooled human MSCs obtained from BM and WJ were intravenously administered into rats with liver fibrosis at a dose of 10 × 10⁶ cells/animal. Sham control and vehicle-treated animals served as negative and disease controls, respectively. The animals were sacrificed at 30 and 70 days after cell transplantation and hepatic-hydroxyproline content, histopathological, and immunohistochemical analyses were performed.

Results

BM-MSCs treatment showed a marked reduction in liver fibrosis as determined by Masson’s trichrome and Sirius red staining as compared to those treated with the vehicle. Furthermore, hepatic-hydroxyproline content and percentage collagen proportionate area were found to be significantly lower in the BM-MSCs-treated group. In contrast, WJ-MSCs treatment showed less reduction of fibrosis at both time points. Immunohistochemical analysis of BM-MSCs-treated liver samples showed a reduction in α-SMA⁺ myofibroblasts and increased number of EpCAM⁺ hepatic progenitor cells, along with Ki-67⁺ and human matrix metalloprotease-1⁺ (MMP-1⁺) cells as compared to WJ-MSCs-treated rat livers.

Conclusions

Our findings suggest that BM-MSCs are more effective than WJ-MSCs in treating liver fibrosis in a CCl₄-induced model in rats. The superior therapeutic activity of BM-MSCs may be attributed to their expression of certain MMPs and angiogenic factors.

Nucleofection optimization and in vitro anti-tumourigenic effect of TRAIL-expressing human adipose-derived mesenchymal stromal cells

Background

Tumour homing capacity of engineered human adipose-derived mesenchymal stromal cells (ADMSCs) expressing anti-tumour agents might be the key for a much safer and yet efficient targeted tumour therapy. However, ADMSCs exhibit resistant to most gene transfection techniques and the use of highly efficient viral vectors has several disadvantages primarily concerning safety risk. Here, we optimized the use of highly efficient and safe nucleofection-based transfection using plasmid encoded for TNF-Related Apoptosis Inducing Ligand (TRAIL) into ADMSCs and investigated the potential anti-tumourigenic of TRAIL-expressing ADMSCs (ADMSCs-TRAIL) on selected cancer models in vitro.

Methods

Different concentration of TRAIL-encoded plasmid and ADMSCs were nucleofected and the percentage of fluorescence cells were analyzed to determine the optimal condition. TRAIL protein and mRNA were validated in nucloeofected ADMSCs using ELISA and RT-PCR respectively. Evaluation of TRAIL specific death receptors were performed on both tumours (A549/lung tumour, LN18/glioblastoma and HepG2/hepatocellular carcinoma) and haematological malignant lines (REH/acute lymphocytic leukaemia, K562/chronic myelogenous leukaemia and KMS-28BM/multiple myeloma) using flow cytometry. ADMSCs-TRAIL was subsequently assessed for anti-tumourigenic properties using both proliferation assay (MTS assay) and apoptosis assay (Annexin-V / Propidium Iodide staining).

Results

Nucleofection showed increased total plasmid concentration (2 μg to 8 μg) resulted in significantly higher reporter expression (11.33% to 39.7%) with slight reduction on cells viability (~10%). ADMSCs-TRAIL significantly inhibited ~50% of cell proliferation in LN18, signifying sensitivity of the cell to ADMSCs-TRAIL mediated inhibition. Inhibition of both tumour and malignant lines proliferation by ADMSCs-TRAIL conditioned medium noticed in HepG2, A549 and REH respectively, whereas K562 and KMS-28BM malignant lines exhibit resistant to ADMSCs-TRAIL mediated inhibition. Moreover, we found that native ADMSCs alone were capable of inducing apoptosis in both LN18 and HepG2 tumour lines, despite substantial increased on the percentage of apoptosis by ADMSCs-TRAIL.

Conclusion

ADMSCs-TRAIL selectively inhibit cancer model and markedly induces apoptosis. Through investigation of the specific TRAIL death receptors expression, we saw that the receptors expression did influence the sensitivity of some but not all cancer lines to TRAIL-mediated inhibition. This study provides further insight into the anti-tumourigenic potential of ADMSCs-TRAIL on different cancer models.