The effect of antagonizing RGD-binding integrin activity in papillary thyroid cancer cell lines

Advances in the Development of Positron Emission Tomography Tracers for Improved Detection of Differentiated Thyroid Cancer

Thyroid cancer poses a significant challenge in clinical management, necessitating precise diagnostic tools and treatment strategies for optimal patient outcomes. This review explores the evolving field of radiotracers in the diagnosis and management of thyroid cancer, focusing on prostate-specific membrane antigen (PSMA)-based radiotracers, fibroblast activation protein inhibitor (FAPI)-based radiotracers, Arg-Gly-Asp (RGD)-based radiotracers, and 18F-tetrafluoroborate (18F-TFB). PSMA-based radiotracers, initially developed for prostate cancer imaging, have shown promise in detecting thyroid cancer lesions; however, their detection rate is lower than 18F-FDG PET/CT. FAPI-based radiotracers, targeting fibroblast activation protein highly expressed in tumors, offer potential in the detection of lymph nodes and radioiodine-resistant metastases. RGD-based radiotracers, binding to integrin αvβ3 found on tumor cells and angiogenic blood vessels, demonstrate diagnostic accuracy in detecting radioiodine-resistant thyroid cancer metastases. 18F-TFB emerges as a promising PET tracer for imaging of lymph node metastases and recurrent DTC, offering advantages over traditional methods. Overall, these radiotracers show promise in enhancing diagnostic accuracy, patient stratification, and treatment selection in differentiated thyroid cancer, warranting further research and clinical validation. Given the promising staging capabilities of 18F-TFB and the efficacy of FAP-targeting tracers in advanced, potentially dedifferentiated cases, continued investigation in these domains is justified.

Exploring the clinical utility of angioinvasion markers in papillary thyroid cancer: a literature review

Papillary thyroid cancer (PTC) is the most common type of thyroid cancer, and angioinvasion, the invasion of blood vessels by cancer cells, is a crucial pathological feature associated with disease progression and poor prognosis. Thus, a comprehensive search of scientific databases was conducted to identify relevant studies investigating angioinvasion markers in PTC. The selected studies were reviewed and analyzed to assess the clinical significance and potential utility of these markers in predicting angioinvasion and guiding treatment decisions. Numerous studies have investigated various markers associated with angioinvasion in PTC, including oxidative stress, vascular endothelial growth factor (VEGF), matrix metalloproteinases (MMPs), and other angiogenic factors. The results indicate that increased expression of these markers is correlated with the presence and extent of angioinvasion in PTC. Moreover, some studies suggest that these markers can serve as prognostic indicators and guide therapeutic strategies, such as selecting patients for more aggressive treatment approaches or targeted therapies. The findings from the reviewed literature highlight the potential clinical utility of angioinvasion markers in PTC. The identification and validation of reliable markers can aid in assessing the risk of angioinvasion, predicting disease progression, and optimizing treatment decisions for patients with PTC. However, further research and validation on larger patient cohorts are necessary to establish the robustness and generalizability of these markers in clinical practice.

Theranostic Options for Radioiodine-Refractory Differentiated Thyroid Carcinoma: Recent Advances, Challenges, and Road Ahead

Radioiodine-refractory differentiated thyroid cancer (RAIR-DTC), though uncommon, presents a considerable therapeutic challenge with poor long-term outcomes. Currently, tyrosine kinase inhibitors are the mainstay of treatment for advanced RAIR-DTC patients. However, these agents are associated with a multitude of adverse events with resultant deterioration in the quality-of-life of the patients. Targeted theranostic approaches with radiolabelled integrin binders and fibroblast activation protein- (FAP)-inhibitors seem to have a promising role in the management of such patients. This mini-review focuses on these novel theranostic strategies in RAIR-DTC, with emphasis on recent advances, existing challenges, and future directions.

Crosstalk Between Abnormal TSHR Signaling Activation and PTEN/PI3K in the Dedifferentiation of Thyroid Cancer Cells

Iodide uptake and the metabolism of thyroid cells are regulated by thyrotropin (TSH)-TSH receptor (TSHR) signaling. Thus, it is necessary to elevate serum TSH levels by T4 withdraw or rTSH administration to facilitate radioiodide (¹³¹I) therapy for differentiated thyroid cancer (DTC). However, non-iodide-avid metastases of DTC which is dedifferentiated do not respond to stimulation by high levels of TSH, suggesting abnormal TSH-TSHR signal transduction in cancer cells. In addition, PI3K/AKT/mTOR signaling activation has been shown to be associated with the dedifferentiated phenotype of thyroid cancer, but the mechanism remains elusive. Therefore, in this study, we aimed to explore the role of abnormal TSH-TSHR signaling activation in regulating iodide uptake and cell mobility in thyroid cancer and its relationship with PI3K/AKT/mTOR signaling. We found that in thyroid cancer cells, TSH binds TSHR coupled to the Gα_12/13 protein and then activates RhoA through interacting with leukemia associated RhoA guanine exchange factor (LARG). This results in a promigration tumorigenic phenotype independent of canonical TSHR-Gα_S signaling that regulates the expression of molecules involved in iodine uptake and metabolism. We observed that signaling pathways downstream of Gα_12/13 signaling were increased, while that of Gα_s signaling was decreased in thyroid cancer cells undergoing dedifferentiation compared to control cells following stimulation with different levels of TSH. PI3K/AKT/mTOR signaling activation enhanced Gα_12/13 signaling through increasing LARG levels but also inhibited the expression of molecules downstream of Gα_s signaling, including thyroid-specific molecules, and iodide uptake. In summary, our results demonstrate the noncanonical activation of TSH-TSHR signaling and its role in increasing the cell mobility and dedifferentiation of thyroid cancer through crosstalk with PI3K/AKT/mTOR signaling.

Role of [99mTc]Tc-Galacto-RGD2 SPECT/CT in identifying metastatic differentiated thyroid carcinoma after thyroidectomy and radioactive iodine therapy

PURPOSE

Integrin αvβ3, a member of the arginine-glycine-aspartate (RGD)-binding subfamily, is associated with tumor angiogenesis and metastasis. The aim of study is to investigate the clinical role of [^99mTc]Tc-Galacto-RGD₂ SPECT/CT in high-risk differentiated thyroid carcinoma (DTC) after thyroidectomy and radioactive iodine (RAI) therapy.

METHODS

Thirty-six patients with high-risk DTC (20 males, 16 females; mean age: 59.9 ± 16.6 y) who underwent thyroidectomy and RAI therapy were consecutively enrolled in this study. All patients underwent [^99mTc]Tc-Galacto-RGD₂ SPECT/CT and diagnostic ¹³¹I whole-body scan 6 months after the last RAI treatment. A region of interest (ROI) was drawn and the ratio of tumor/non-target (T/NT) was calculated. Per-patient and per-lesion analysis was performed to evaluate the diagnostic efficacy. The final diagnosis was confirmed by histopathology and follow-up. Integrin αvβ3, CD31, and Ki-67 expression in the tumor were also analyzed for evaluation of angiogenesis and proliferation.

RESULTS

Out of 36 patients, twenty-two had metastatic disease. By per-patient analysis, the area under the curve of [^99mTc]Tc-Galacto-RGD₂ SPECT/CT was marginally significantly higher than that of ¹³¹I whole-body scan and morphological imaging (P = 0.0034 and 0.0006). For per-lesion analysis, [^99mTc]Tc-Galacto-RGD₂ SPECT/CT identified 67 metastatic lymph nodes in 14 patients, 12 lung metastases in four patients, and 12 bone metastases in six patients; its sensitivity was significantly higher than that of ¹³¹I whole-body scan in detection of lymphatic (90.54% vs. 55.41%, P = 0.0124) and bone metastasis (92.31% vs. 30.77%, P = 0.046). The ratio of T/NT in metastatic lesions increased with the DTC upstaging.

CONCLUSIONS

[^99mTc]Tc-Galacto-RGD₂ SPECT/CT has high sensitivity in the detection of metastasis in high-risk DTC and further contributes to evaluation of tumor angiogenesis and radio‑iodine refractory status.

Clinical Value of 99mTc-3PRGD2 SPECT/CT in Differentiated Thyroid Carcinoma with Negative 131I Whole-Body Scan and Elevated Thyroglobulin Level

The aim of this study was to assess the usefulness of integrin imaging with ^99mTc-PEG₄-E[PEG₄-c(RGDfK)]₂ (^99mTc-3PRGD2) single photon emission computed tomography (SPECT)/computed tomography (CT) in detecting recurrent disease in patients with differentiated thyroid cancer (DTC), negative radioiodine whole-body scan (WBS) and high serum thyroglobulin (Tg). Thirty-seven patients who underwent total thyroidectomy followed by radioactive iodine ablation and had negative radioiodine WBS but elevated Tg levels were included. ^99mTc-3PRGD2 SPECT/CT was performed 1 week after the negative diagnostic ¹³¹I WBS. Diagnostic performance indicators, including sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), for ^99mTc-3PRGD2 SPECT/CT was calculated. The correlations between SPECT/CT results and clinic-pathological characteristics were examined. In 30 (81.1%) of the 37 patients, ^99mTc-3PRGD2 SPECT/CT showed positive uptake. The sensitivity, specificity, PPV, and NPV of SPECT/CT to detect recurrent disease at follow-up were 96.6%, 75%, 93.3% and 85.7%, respectively. The sensitivity and PPV of SPECT/CT increased with increasing serum Tg levels. ^99mTc-3PRGD2 SPECT/CT showed high sensitivity and PPV in the detection of recurrence among DTC patients with higher Tg levels and negative WBS, and the probability of obtaining a positive SPECT/CT result was related with the level of Tg.