Decreased expression of p27 is associated with malignant transformation and extrathyroidal extension in papillary thyroid carcinoma

CDK4 phosphorylation status and rational use for combining CDK4/6 and BRAF/MEK inhibition in advanced thyroid carcinomas

Background

CDK4/6 inhibitors (CDK4/6i) have been established as standard treatment against advanced Estrogen Receptor-positive breast cancers. These drugs are being tested against several cancers, including in combinations with other therapies. We identified the T172-phosphorylation of CDK4 as the step determining its activity, retinoblastoma protein (RB) inactivation, cell cycle commitment and sensitivity to CDK4/6i. Poorly differentiated (PDTC) and anaplastic (ATC) thyroid carcinomas, the latter considered one of the most lethal human malignancies, represent major clinical challenges. Several molecular evidence suggest that CDK4/6i could be considered for treating these advanced thyroid cancers.

Methods

We analyzed by two-dimensional gel electrophoresis the CDK4 modification profile and the presence of T172-phosphorylated CDK4 in a collection of 98 fresh-frozen tissues and in 21 cell lines. A sub-cohort of samples was characterized by RNA sequencing and immunohistochemistry. Sensitivity to CDK4/6i (palbociclib and abemaciclib) was assessed by BrdU incorporation/viability assays. Treatment of cell lines with CDK4/6i and combination with BRAF/MEK inhibitors (dabrafenib/trametinib) was comprehensively evaluated by western blot, characterization of immunoprecipitated CDK4 and CDK2 complexes and clonogenic assays.

Results

CDK4 phosphorylation was detected in all well-differentiated thyroid carcinomas (n=29), 19/20 PDTC, 16/23 ATC and 18/21 thyroid cancer cell lines, including 11 ATC-derived ones. Tumors and cell lines without phosphorylated CDK4 presented very high p16CDKN2A levels, which were associated with proliferative activity. Absence of CDK4 phosphorylation in cell lines was associated with CDK4/6i insensitivity. RB1 defects (the primary cause of intrinsic CDK4/6i resistance) were not found in 5/7 tumors without detectable phosphorylated CDK4. A previously developed 11-gene expression signature identified the likely unresponsive tumors, lacking CDK4 phosphorylation. In cell lines, palbociclib synergized with dabrafenib/trametinib by completely and permanently arresting proliferation. These combinations prevented resistance mechanisms induced by palbociclib, most notably Cyclin E1-CDK2 activation and a paradoxical stabilization of phosphorylated CDK4 complexes.

Conclusion

Our study supports further clinical evaluation of CDK4/6i and their combination with anti-BRAF/MEK therapies as a novel effective treatment against advanced thyroid tumors. Moreover, the complementary use of our 11 genes predictor with p16/KI67 evaluation could represent a prompt tool for recognizing the intrinsically CDK4/6i insensitive patients, who are potentially better candidates to immediate chemotherapy.

Can We Predict Differentiated Thyroid Cancer Behavior? Role of Genetic and Molecular Markers

Thyroid cancer is ranked in ninth place among all the newly diagnosed cancer cases in 2020. Differentiated thyroid cancer behavior can vary from indolent to extremely aggressive. Currently, predictions of cancer prognosis are mainly based on clinicopathological features, which are direct consequences of cell and tissue microenvironment alterations. These alterations include genetic changes, cell cycle disorders, estrogen receptor expression abnormalities, enhanced epithelial-mesenchymal transition, extracellular matrix degradation, increased hypoxia, and consecutive neovascularization. All these processes are represented by specific genetic and molecular markers, which can further predict thyroid cancer development, progression, and prognosis. In conclusion, evaluation of cancer genetic and molecular patterns, in addition to clinicopathological features, can contribute to the identification of patients with a potentially worse prognosis. It is essential since it plays a crucial role in decision-making regarding initial surgery, postoperative treatment, and follow-up. To date, there is a large diversity in methodologies used in different studies, frequently leading to contradictory results. To evaluate the true significance of predictive markers, more comparable studies should be conducted.

CDKN1B Mediates Apoptosis of Neuronal Cells and Inflammation Induced by Oxyhemoglobin via miR-502-5p After Subarachnoid Hemorrhage

Subarachnoid hemorrhage is a common disease in the neural system, which causes high fatality rate. Therefore, it is necessary to figure out inner mechanisms of factors related to this disease. RT-qPCR was applied for measuring expressions of CDKN1B and miR-502-5p and other factors of apoptosis and inflammation. Cell viabilities were detected through CCK-8. Binding conditions between miR-502-5p and CDKN1B were detected through luciferase report assay. Western blot was used for measuring levels of proteins in PPARγ/NF-κB signaling pathway. Apoptosis and inflammation of HT22 cell line, a kind of nerve cell line, were enhanced and viabilities were suppressed by oxyhemoglobin. CDKN1B expressed lower in induced HT22 cell line and overexpressed CDKN1B could promote viabilities and suppress apoptosis as well as inflammation. MiR-502-5p was the target gene of CDKN1B and enhanced apoptosis and inflammation of cells in HT22 cell line. Furthermore, miR-502-5p reversed functions of CKDN1B in induced cells through regulating proteins in PPARγ/NF-κB signaling pathway. CDKN1B was the gene that could inhibit SAH caused by apoptosis in nerve cells and inflammation by sponging miR-502-5p and regulating factors in PPARγ/NF-κB signaling pathway, suggesting it could be a factor for protecting functions of nerve cells after SAH.

Clinicopathological significance of loss of p27kip1 expression in papillary thyroid carcinoma

INTRODUCTION

A meta-analysis was done to investigate the clinicopathological significance of the loss of p27kip1 expression in papillary thyroid carcinoma (PTC).

METHODS

The meta-analysis involving 17 studies included 1,652 PTC and 328 benign cases. The rate of p27kip1 expression loss in PTC and benign lesions, and the correlations between p27kip1 expression loss and clinicopathological characteristics of PTC were determined.

RESULTS

The estimated rate of p27kip1 expression loss was 0.557 (95% confidence interval [CI] 0.443-0.665) and 0.139 (95% CI 0.062-0.283) in PTC and benign lesions, respectively. In subgroup analysis, the rates of p27kip1 expression loss were 0.683, 0.393, and 0.414 in the classical variant, follicular variant, and papillary thyroid microcarcinoma, respectively. Loss of p27kip1 expression was significantly correlated with lymph node metastasis and distant metastasis (odds ratio 3.559, 95% CI 1.146-11.056 and 4.735, 95% CI 1.322-16.960, respectively). Extrathyroidal extension was correlated with loss of p27kip1 expression, but not in a statistically significant way (p = 0.051). There were no significant correlations between loss of p27kip1 expression and sex, tumor size, BRAFV600E mutation, and tumor multifocality.

CONCLUSIONS

Loss of p27kip1 expression is frequently found in PTC compared with benign lesions and normal thyroid tissue. When present in PTC, it is correlated with aggressive tumor behavior.