Targeted radioimmunotherapy with the iodine-131-labeled caerin 1.1 peptide for human anaplastic thyroid cancer in nude mice

Engineered Antibodies as Cancer Radiotheranostics

Radiotheranostics is a rapidly growing approach in personalized medicine, merging diagnostic imaging and targeted radiotherapy to allow for the precise detection and treatment of diseases, notably cancer. Radiolabeled antibodies have become indispensable tools in the field of cancer theranostics due to their high specificity and affinity for cancer-associated antigens, which allows for accurate targeting with minimal impact on surrounding healthy tissues, enhancing therapeutic efficacy while reducing side effects, immune-modulating ability, and versatility and flexibility in engineering and conjugation. However, there are inherent limitations in using antibodies as a platform for radiopharmaceuticals due to their natural activities within the immune system, large size preventing effective tumor penetration, and relatively long half-life with concerns for prolonged radioactivity exposure. Antibody engineering can solve these challenges while preserving the many advantages of the immunoglobulin framework. In this review, the goal is to give a general overview of antibody engineering and design for tumor radiotheranostics. Particularly, the four ways that antibody engineering is applied to enhance radioimmunoconjugates: pharmacokinetics optimization, site-specific bioconjugation, modulation of Fc interactions, and bispecific construct creation are discussed. The radionuclide choices for designed antibody radionuclide conjugates and conjugation techniques and future directions for antibody radionuclide conjugate innovation and advancement are also discussed.

Computational studies and synthesis of 131iodine-labeled nocardiotide A analogs as a peptide-based theragnostic radiopharmaceutical ligand for cancer targeting SSTR2

Radiolabeled peptides belong to a highly specific group of radiotracers used in oncology, particularly for diagnostics and cancer therapy. With the notable advantages of high binding affinity and selectivity to cancer cells, they have proven to be very useful in nuclear medicine. As a result, efforts have been focused on discovering new peptide sequences for radiopeptide preparation. Nocardiotide A, a cyclic hexapeptide comprising the amino acids cyclo-Trp-Ile-Trp-Leu-Val-Ala (cWIWLVA) isolated from Nocardiopsis sp., has shown significant cytotoxicity against cancer cells, rendering it a suitable candidate for the process. Therefore, the present study aimed to design a stable and effective radiopeptide by labeling nocardiotide A with iodine-131 (131I), ensuring that its affinity to SSTR2 is not compromised. In silico study showed that structural modification of nocardiotide A labeled with 131iodine exhibited good affinity value, forming hydrogen bonds with key residues, such as Q.102 and T.194, which are essential in SSTR2. Based on the results, cyclic hexapeptides of cWIWLYA were selected for further synthesis, and its peptide product was confirmed by the presence of an ionic molecule peak m/z [M + Na]+ 855.4332 (yield, 25.60%). In vitro tests conducted on cWIWLYA showed that cWIWLYA can bind to HeLa cancer cells. Radiopeptide synthesis was initiated with radiolabeling of cWIWLYA by 131I using the chloramine-T method that showed a radiochemical yield of 93.37%. Non-radioactive iodine labeling reaction showed that iodination was successful, which detected the presence of di-iodinated peptide (I2-cWIWLYA) with m/z [M + Na]+ 1107.1138. In summary, a radiopeptide derived from nocardiotide A showed great potential for further development as a diagnostic and therapeutic agent in cancer treatment.

Amphibian-Derived Natural Anticancer Peptides and Proteins: Mechanism of Action, Application Strategies, and Prospects

Cancer is one of the major diseases that seriously threaten human life. Traditional anticancer therapies have achieved remarkable efficacy but have also some unavoidable side effects. Therefore, more and more research focuses on highly effective and less-toxic anticancer substances of natural origin. Amphibian skin is rich in active substances such as biogenic amines, alkaloids, alcohols, esters, peptides, and proteins, which play a role in various aspects such as anti-inflammatory, immunomodulatory, and anticancer functions, and are one of the critical sources of anticancer substances. Currently, a range of natural anticancer substances are known from various amphibians. This paper aims to review the physicochemical properties, anticancer mechanisms, and potential applications of these peptides and proteins to advance the identification and therapeutic use of natural anticancer agents.

Experimental study of 131I-caerin 1.1 and 131I-c(RGD)2 for internal radiation therapy of esophageal cancer xenografts

OBJECTIVE

The aim of this study was to analyze and compare the therapeutic effects of 131I-caerin 1.1 and 131I-c(RGD)2 on TE-1 esophageal cancer cell xenografts.

METHODS

(1) The in vitro antitumor effects of the polypeptides caerin 1.1 and c(RGD)2 were verified by MTT and clonogenic assays. 131I-caerin 1.1 and 131I-c(RGD)2 were prepared by chloramine-T (Ch-T) direct labeling, and their basic properties were measured. The binding and elution of 131I-caerin 1.1, 131I-c(RGD)2, and Na131I (control group) in esophageal cancer TE-1 cells were studied through cell binding and elution assays. (2) The antiproliferative effect and cytotoxicity of 131I-caerin 1.1, 131I-c(RGD)2, Na131I, caerin 1.1 and c(RGD)2 on TE-1 cells were detected by Cell Counting Kit-8 (CCK-8) assay. (3) A nude mouse esophageal cancer (TE-1) xenograft model was established to study and compare the efficacy of 131I-caerin 1.1 and 131I-c(RGD)2 in internal radiation therapy for esophageal cancer.

RESULTS

(1) Caerin 1.1 inhibited the in vitro proliferation of TE-1 cells in a concentration-dependent manner, with an IC50 of 13.00 µg/mL. The polypeptide c(RGD)2 had no evident inhibitory effect on the in vitro proliferation of TE-1 cells. Therefore, the antiproliferative effects of caerin 1.1 and c(RGD)2 on esophageal cancer cells were significantly different (P < 0.05). The clonogenic assay showed that the clonal proliferation of TE-1 cells decreased as the concentration of caerin 1.1 increased. Compared with the control group (drug concentration of 0 µg/mL), the caerin 1.1 group showed significantly lower clonal proliferation of TE-1 cells (P < 0.05). (2) The CCK-8 assay showed that 131I-caerin 1.1 inhibited the in vitro proliferation of TE-1 cells, while 131I-c(RGD)2 had no evident inhibitory effect on proliferation. The two polypeptides showed significantly different antiproliferative effects on esophageal cancer cells at higher concentrations (P < 0.05). Cell binding and elution assays showed that 131I-caerin 1.1 stably bound to TE-1 cells. The cell binding rate of 131I-caerin 1.1 was 15.8 % ± 1.09 % at 24 h and 6.95 % ± 0.22 % after 24 h of incubation and elution. The cell binding rate of 131I-c(RGD)2 was 0.06 % ± 0.02 % at 24 h and 0.23 % ± 0.11 % after 24 h of incubation and elution. (3) In the in vivo experiment, 3 days after the last treatment, the tumor sizes of the phosphate-buffered saline (PBS) group, caerin 1.1 group, c(RGD)2 group, 131I group, 131I-caerin 1.1 group, and 131I-c(RGD)2 group were 68.29 ± 2.67 mm3, 61.78 ± 3.58 mm3, 56.67 ± 5.65 mm3, 58.88 ± 1.71 mm3, 14.40 ± 1.38 mm3, and 60.14 ± 0.47 mm3, respectively. Compared with the other treatment groups, the 131I-caerin 1.1 group had significantly smaller tumor sizes (P < 0.001). After treatment, the tumors were isolated and weighed. The tumor weights in the PBS group, caerin 1.1 group, c(RGD)2 group, 131I group, 131I-caerin 1.1 group, and 131I-c(RGD)2 group were 39.50 ± 9.54 mg, 38.25 ± 5.38 mg, 38.35 ± 9.53 mg, 28.25 ± 8.50 mg, 9.50 ± 4.43 mg, and 34.75 ± 8.06 mg, respectively. The tumor weights in the 131I-caerin 1.1 group were significantly lighter than those in the other groups (P < 0.01).

CONCLUSION

131I-caerin 1.1 has tumor-targeting properties, is capable of targeted binding to TE-1 esophageal cancer cells, can be stably retained in tumor cells, and has an evident cytotoxic killing effect, while 131I-c(RGD)2 has no evident cytotoxic effect. 131I-caerin 1.1 better suppressed tumor cell proliferation and tumor growth than pure caerin 1.1, 131I-c(RGD)2, and pure c(RGD)2.

Advances in Antioxidant Applications for Combating 131I Side Effects in Thyroid Cancer Treatment

Thyroid cancer is the most common endocrine cancer, and its prevalence has been increasing for decades. Approx. 95% of differentiated thyroid carcinomas are treated using ¹³¹iodine (¹³¹I), a radionuclide with a half-life of 8 days, to achieve optimal thyroid residual ablation following thyroidectomy. However, while ¹³¹I is highly enriched in eliminating thyroid tissue, it can also retain and damage other body parts (salivary glands, liver, etc.) without selectivity, and even trigger salivary gland dysfunction, secondary cancer, and other side effects. A significant amount of data suggests that the primary mechanism for these side effects is the excessive production of reactive oxygen species, causing a severe imbalance of oxidant/antioxidant in the cellular components, resulting in secondary DNA damage and abnormal vascular permeability. Antioxidants are substances that are capable of binding free radicals and reducing or preventing the oxidation of the substrate in a significant way. These compounds can help prevent damage caused by free radicals, which can attack lipids, protein amino acids, polyunsaturated fatty acids, and double bonds of DNA bases. Based on this, the rational utilization of the free radical scavenging function of antioxidants to maximize a reduction in ¹³¹I side effects is a promising medical strategy. This review provides an overview of the side effects of ¹³¹I, the mechanisms by which ¹³¹I causes oxidative stress-mediated damage, and the potential of natural and synthetic antioxidants in ameliorating the side effects of ¹³¹I. Finally, the disadvantages of the clinical application of antioxidants and their improving strategies are prospected. Clinicians and nursing staff can use this information to alleviate ¹³¹I side effects in the future, both effectively and reasonably.

131I-Caerin 1.1 and 131I-Caerin 1.9 for the treatment of non-small-cell lung cancer

Objective

To investigate the effect of the ¹³¹I-labeled high-affinity peptides Caerin 1.1 and Caerin 1.9 for the treatment of A549 human NSCLC cells.

Methods

① 3-[4,5-Dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide (MTT) and plate clone formation assays were performed to confirm the in vitro anti-tumor activity of Caerin 1.1 and Caerin 1.9. ② Chloramine-T was used to label Caerin 1.1 and Caerin 1.9 with ¹³¹I, and the Cell Counting Kit 8 assay was performed to analyze the inhibitory effect of unlabeled Caerin 1.1, unlabeled Caerin 1.9, ¹³¹I-labeled Caerin 1.1, and ¹³¹I-labeled Caerin 1.9 on the proliferation of NSCLC cells. An A549 NSCLC nude mouse model was established to investigate the in vivo anti-tumor activity of unlabeled Caerin 1.1, unlabeled Caerin 1.9, ¹³¹I-labeled Caerin 1.1, and ¹³¹I-labeled Caerin 1.9.

Results

① Caerin 1.1 and Caerin 1.9 inhibited the proliferation of NSCLC cells in vitro in a concentration-dependent manner. The half-maximal inhibitory concentration was 16.26 µg/ml and 17.46 µg/ml, respectively, with no significant intergroup difference (P>0.05). ② ¹³¹I-labeled Caerin 1.1 and ¹³¹I-labeled Caerin 1.9 were equally effective and were superior to their unlabeled versions in their ability to inhibit the proliferation and growth of NSCLC cells (P>0.05).

Conclusions

¹³¹I-labeled Caerin 1.1 and ¹³¹I-labeled Caerin 1.9 inhibit the proliferation and growth of NSCLC cells and may become potential treatments for NSCLC.

Caerin 1 Peptides, the Potential Jack-of-All-Trades for the Multiple Antibiotic-Resistant Bacterial Infection Treatment and Cancer Immunotherapy

Antibiotic resistance-related bacterial infections and cancers become huge challenges in human health in the 21^st century. A number of naturally derived antimicrobial peptides possess multiple functions in host defense, including anti-infective and anticancer activities. One of which is known as the caerin 1 family peptides. The microbicidal properties of these peptides have been long discussed. The recent studies also established the usage of two members in this family, caerin 1.1 and caerin 1.9, in antimultiple antibiotic-resistant bacteria species. It is increasingly evident that caerin 1.1 and caerin 1.9 also contain additional activities in the suppression of tumor. In this review, we briefly outline the therapeutic potentials and possible mechanism of action of caerin 1.1 and 1.9 in the treatment of multiple antibiotic-resistant bacterial infection and cancer immunotherapy.