Minigastrin (also mini gastrin) is a form of

gastrin Gastrin is a peptide hormone that stimulates secretion of gastric acid (HCl) by the parietal cells of the stomach and aids in gastric motility. It is released by G cells in the pyloric antrum of the stomach, duodenum, and the pancreas. Gastrin ...

. Its sequence is H-Leu-Glu-Glu-Glu-Glu-Glu-Ala-Tyr-Gly-Trp-Met-Asp-Phe-NH2. Minigastrin has shown to be a potential therapeutic agent for thyroid carcinoma by targeting cancer-promoting

cholecystokinin receptor Cholecystokinin receptors or CCK receptors are a group of G-protein coupled receptors which bind the peptide hormones cholecystokinin (CCK) and gastrin. There are two different subtypes CCKA and CCKB which are ~50% homologous: Various cholecy ...

s. A 2018 study further elaborates by using radiochemical labeling to show that

Indium-111 Indium-111 (111In) is a radioactive isotope of indium (In). It decays by electron capture to stable cadmium-111 with a half-life of 2.8 days. Indium-111 chloride (111InCl) solution is produced by proton irradiation of a cadmium target (112Cd(p,2n) ...

labeled minigastrin peptides showing to have stronger affinity to

cholecystokinin B receptor The cholecystokinin B receptor also known as CCKBR or CCK2 is a protein that in humans is encoded by the ''CCKBR'' gene. This gene encodes a G protein-coupled receptor for gastrin and cholecystokinin (CCK), regulatory peptides of the brain and g ...

s (CCK2) in neuroendocrine cancers.

Biological Applications

''Peptide Receptor Radionuclide Therapy (PRRT)'' A radioactively labeled analogue of minigastrin, PP-F11, conjugated with NOTA, DOTA, or NODAGA was studied to view the effects they have on peptide receptor radionuclide therapy (PRRT) and cancer cell tracing. When mice with CCK2 tumors were injected with 64Cu-labeled DOTA-PP-F11, NOTA-PP-F11, and NODAGA-PP-F11, the mice labeled with NOTA displayed a tumor uptake o 7.20 ± 0.44% ID/g and a high tumor-to-blood ratio. Further studies are being investigated on how to reduce the background levels to obtain clearer images. ''Increasing Tumor Uptake'' The inhibition of rapamycin complex 1 was discovered to improve the tumor uptake of radioactively labeled minigastrin. In a study conducted in 2021, treatment of A431/CCKBR tumor cells were assessed with DOTA-PP-F11N. This treatment in combination with RAD001 in mice, resulted in an average size tumor reduction of about 0.3 cm³ in comparison to the control group which had an average tumor size of 0.97 cm³. The treatment group also had a higher survival rate where the control group median life span was 19.5 days and the group that received treatment had an average life span of 43 days.

References

Peptide hormones {{biochem-stub