Construction of an alpaca immune antibody library for the selection of nanobodies against Drosophila melanogaster proteins

Introduction: Drosophila melanogaster is a model organism for studying developmental biology and human neural disorders. Nanobodies are the variable domains of the heavy chains of camelid heavy-chain antibodies (VHHs) with high affinity to their antigens and have applications in basic research, similar to traditional antibodies. In addition, nanobodies acting as functionalized antibodies or protein binders have become an additional valuable approach in Drosophila. This study aimed to develop a VHH library against Drosophila proteins and confirm its availability by retrieving some Drosophila protein-specific nanobodies from the library. Methods: An alpaca was first immunized with Drosophila embryo lysate and then its lymphocytes were isolated. Total RNA was extracted and cDNA was synthesized. The vhh sequences were amplified by two round PCR, which were then ligated to a phage display vector pADL-10b. The ligation products were transduced into SS320 competent cells to generate a VHH library. From this library, nanobodies against CG7544, Myc, and CyclinE was enriched and screened by phage display technology and ELISA. DNA sequences of identified nanobodies were cloned into pADL-10b-Flag-His for expression and purification in Escherichia coli SS320. Binding ability of purified nanobodies with corresponding antigens were determined by ELISA and surface plasmon resonance in vitro. Results: In this study, an immune VHH library against Drosophila embryo proteins was generated with a capacity of 3 × 10⁷. From this library, eight nanobodies against three Drosophila proteins, Myc, CyclinE, and CG7544, were identified and the DNA sequences of these nanobodies were obtained. These nanobodies were successfully expressed and purified from Escherichia coli SS320, and were demonstrated to bind corresponding antigens with high affinity in vitro. Moreover, the equilibrium constant between the highest enriched nanobodies and corresponding antigens were calculated. Conclusion: In summary, we report the availability of an immune VHH library and a highly efficient panning strategy for nanobodies against proteins in Drosophila.

The Regulatory Effects of CDKN1A on Relevant Genes in Kaposi's Sarcoma Cells

The cyclin-dependent kinase inhibitor 1A (CDKN1A) gene plays important roles in different types of cancer; however, its mechanism in Kaposi's Sarcoma (KS) is far less known. The aim of this study is to investigate the regulatory effects of CDKN1A on relevant genes in KS cells, and ultimately determine the role of CDKN1A in KS. In the study, the CDKN1A overexpression group, or siRNA group, was transfected into KS cells, respectively. Western-Blot (WB) and quantitative real-time polymerase chain reactions (q-PCR) were performed to detect the expression of cell cycle protein D1 (CyclinD1) and cell cycle protein E (CyclinE). Q-PCR was performed to determine the expression of kshv-mir-k12-1-5p. The results prove that CDKN1A negatively regulates the expression of CyclinD1, CyclinE, and kshv-mir-k1-2-1-5p. Therefore, CDKN1A may be involved in the formation and development of KS through the regulation of kshv-mir-k12-1-5p, CyclinD1, and CyclinE. CDKN1A may become a new choice for targeted therapy in KS.

MiR-140 Expression Regulates Cell Proliferation and Targets PD-L1 in NSCLC

BACKGROUND/AIMS

Programmed death ligand1(PD-L1) plays a role in the development and progression of non-small cell lung cancer (NSCLC). This study aimed to identify miRNA(s) that are responsible for regulation of expression of PD-L1 in NSCLC, and to investigate the role of PD-L1 in regulation of the cell cycle in NSCLC.

METHODS

We predicted the target miRNA of PD-L1, which was miR-140, using the online tools TargetScan and miBase. In NSCLC cells obtained from clinical specimens, in addition to A549 and NCI-H1650 cell cultures, western blots were used to detect the level of expression of proteins, while real-time PCR was used to determine the level of expression of PD-L1, miR-140, cyclin E, and β-actin. Transfection with miR-140 mimics, miR-140 inhibitors, and PD-L1 siRNA were conducted using commercial kits. To determine whether miR-140 directly binds PD-L1, a luciferase reporter gene with wild type or mutated PD-L1 was used. Cell viability was measured with the MTT assay, and PI staining was used for cell cycle analysis.

RESULTS

We found low expression of miR-140 and high expression of PD-L1 and cyclin E in NSCLC cells. Over-expression of miR-140 suppressed the expression of PD-L1 by directly binding its 3' UTR, and was also associated with decreased expression of cyclin E and inhibition of cellular proliferation in A549 and NCI-H1650 cells. Inhibition of PD-L1, in the absence of manipulations to miR-140, also decreased the expression of cyclin E.

CONCLUSION

We conclude that miR-140 directly suppresses PD-L1 and inhibits the miR-140/PD-L1/cyclin E pathway in NSCLC.

Expression of cell cycle regulator p57kip2, cyclinE protein and proliferating cell nuclear antigen in human pancreatic cancer: An immunohistochemical study

AIM: To investigate the effects of p57^kip2, cyclinE protein and proliferating cell nuclear antigen (PCNA) on occurrence and progression of human pancreatic cancer.

METHODS: The expression of p57^kip2, cyclinE protein and PCNA in tumor tissues and adjacent tissues from 32 patients with pancreatic cancer was detected by SP immunohistochemical technique.

RESULTS: The positive expression rate of p57^kip2 protein in tumor tissues was 46.9%, which was lower than that in adjacent pancreatic tissues (χ² = 5.317, P<0.05). p57^kip2 protein positive expression remarkably correlated with tumor cell differentiation (P<0.05), but not with lymph node metastasis (P>0.05). The positive expression rate of cyclinE protein in tumor tissues was 68.8%, which was higher than that in adjacent pancreatic tissues (χ² = 4.063, P<0.05). CyclinE protein positive expression significantly correlated with tumor cell differentiation and lymph node metastasis (P<0.05). The positive expression rate of PCNA in the tumor tissues was 71.9%, which was higher than that in adjacent pancreatic tissues (χ² = 5.189, P<0.05). PCNA positive expression remarkably correlated with tumor cell differentiation and lymph node metastasis (P<0.05).

CONCLUSION: The decreased expression of p57^kip2 and/or overexpression of cyclinE protein and PCNA may contribute to the occurrence and progression of pancreatic cancer. p57^kip2, cyclinE protein, and PCNA play an important role in occurrence and progression of pancreatic cancer.