Preparation and Identification of HER2 Radioactive Ligands and Imaging Study of Breast Cancer-Bearing Nude Mice

131I-Labeled Anti-HER2 Nanobody for Targeted Radionuclide Therapy of HER2-Positive Breast Cancer

Purpose

The unique structure of nanobodies is advantageous for the development of radiopharmaceuticals for nuclear medicine. Nanobodies targeted to human epidermal growth factor receptor 2 (HER2) can be used as tools for the imaging and therapy of HER2-overexpressing tumors. In this study, we aimed to describe the generation of a ¹³¹I-labeled anti-HER2 nanobody as a targeted radionuclide therapy (TRNT) agent for HER2-positive breast cancer.

Methods

The anti-HER2 nanobody NM-02 was labeled with ¹³¹I using the iodogen method, and its radiochemical purity and stability in vitro were assessed. The pharmacokinetic profile of ¹³¹I-NM-02 was investigated in normal mice. Tumor accumulation, biodistribution, and therapeutic potential of ¹³¹I-NM-02 were evaluated in HER2-positive SKBR3 xenografts; HER2-negative MB-MDA-231 xenografts were used as the control group.

Results

¹³¹I-NM-02 could be readily prepared with satisfactory radiochemical purity and stability in vitro. Apparent tumor uptake was observed in HER2-positive tumor-bearing mice with rapid blood clearance and favorable biodistribution. ¹³¹I-NM-02 could significantly inhibit tumor growth and extend the life of these mice with good organ compatibility. Negligible tumor accumulation and inhibitory effects of ¹³¹I-NM-02 were observed in the negative control group.

Conclusion

¹³¹I-NM-02 has the potential to be explored as a novel tool for TRNT of HER2-positive breast cancer.

Transcriptomics-based screening of molecular signatures associated with patients overall survival and their key regulators in subtypes of breast cancer

Molecular subtypes of breast cancer are associated with differences in prognosis and strategies of molecular targeted therapies. Gene regulatory mechanisms as one of the reasons might modulate these differences. In the present study, we proposed a comprehensive data analysis and systems biology approach to explore molecular signatures which reduce the chance of patients overall survival and the possible mechanisms of their regulation by transcription factors (TFs) and microRNAs (miRNAs) in the main subtypes of breast tumor consist of Basal like, Her2 enriched, Luminal A and Luminal B breast cancer. In this regards, we used available microarray datasets to assess common differentially expressed genes (DEGs) in breast cancer subtypes. Using Kaplan-Meier curve analysis we identified common DEGs which are associated with decreasing in the overall survival of breast cancer patients. Furthermore, gene regulatory networks (GRNs) were depicted based on TFs and miRNAs with interest target genes. Then GRNs were analyzed and using five algorithms (Control centrality, Betweenness, Degree, Classification, and MCDS) the key regulators were identified for each subtype. In this study, we highlighted mechanisms underlying the regulation of breast cancer molecular signatures by TFs and miRNAs which their alteration reduce the chance of survival rate in each subtype of breast cancer. Our current study in a holistic insight revealed the importance of some genes and their regulators as potential prognostic markers and/or therapeutic targets in breast cancer patients.

99mTc-HYNIC-(tricine/EDDA)-FROP peptide for MCF-7 breast tumor targeting and imaging

Background

Breast cancer is the most common malignancy among women in the world. Development of novel tumor-specific radiopharmaceuticals for early breast tumor diagnosis is highly desirable. In this study we developed ^99mTc-HYNIC-(tricine/EDDA)-Lys-FROP peptide with the ability of specific binding to MCF-7 breast tumor.

Methods

The FROP-1 peptide was conjugated with the bifunctional chelator hydrazinonicotinamide (HYNIC) and labeled with ^99mTc using tricine/EDDA co-ligand. The cellular specific binding of ^99mTc-HYNIC-FROP was evaluated on different cell lines as well as with blocking experiment on MCF-7 (human breast adenocarcinoma). The tumor targeting and imaging of this labeled peptide were performed on MCF-7 tumor bearing mice.

Results

Radiochemical purity for ^99mTc-HYNIC-(tricine/EDDA)-FROP was 99% which was determined with ITLC method. This radiolabeled peptide showed high stability in normal saline and serum about 98% which was monitored with HPLC method. In saturation binding experiments, the binding constant (K_d) to MCF-7 cells was determined to be 158 nM. Biodistribution results revealed that the ^99mTc-HYNIC-FROP was mainly exerted from urinary route. The maximum tumor uptake was found after 30 min post injection (p.i.); however maximum tumor/muscle ratio was seen at 15 min p.i. The tumor uptake of this labeled peptide was specific and blocked by co-injection of excess FROP. According to the planar gamma imaging result, tumor was clearly visible due to the tumor uptake of ^99mTc-HYNIC-(tricine/EDDA)-FROP in mouse after 15 min p.i.

Conclusions

The ^99mTc-HYNIC-(tricine/EDDA)-FROP is considered a promising probe with high specific binding to MCF-7 breast cancer cells.