Incidental Detection of TFEB-Amplified Renal Cell Carcinoma by Colocated Gene Amplification of CCND3 (6p21): A Case Report and Review of the Literature.

TFEB-amplified renal cell carcinoma (RCC), which belongs to the MITF family of RCC, is characterized by genomic amplification at the 6p21.1 locus where the TFEB gene is located. The vascular endothelial growth factor A and cyclin D3 genes are also located at this same locus. When tumors lack classic morphologic features, they may be classified as "RCC not otherwise specified (NOS)." However, it is increasingly important to accurately diagnose the RCC subtype to define the patient's individual prognosis and select the subsequent therapeutic modalities, which now include targeted agents. Therefore, knowledge of the diagnostic features of TFEB-altered RCCs, such as t(6;11) RCCs and TFEB-amplified RCCs, is critical for identifying these tumors. Herein, we present an interesting case of TFEB-amplified RCC that was initially diagnosed as RCC NOS on biopsy of a renal tumor in a community practice setting with available molecular findings demonstrating CCND3 amplification. The genetic abnormality was "accidentally" detected due to the amplification of the colocated CCND3 gene at the 6p21 locus of the TFEB gene on a limited genetic sequencing panel. This case highlights the importance of molecular tests in accurately diagnosing RCC and carefully interpreting molecular findings in the context of histomorphologic features.

The Cyclin D3 Protein Enforces Monogenic TCRß Expression by Mediating TCRß Protein-Signaled Feedback Inhibition of Vß Recombination.

In jawed vertebrates, adaptive immunity depends on the process of V(D)J recombination creating vast numbers of T and B lymphocytes that each expresses unique Ag receptors of uniform specificity. The asynchronous initiation of V-to-(D)J rearrangement between alleles and the resulting protein from one allele signaling feedback inhibition of V recombination on the other allele ensures homogeneous receptor specificity of individual cells. Upon productive Vß-to-DßJß rearrangements in noncycling double-negative thymocytes, TCRß protein signals induction of the cyclin D3 protein to accelerate cell cycle entry, thereby driving proliferative expansion of developing αß T cells. Through undetermined mechanisms, the inactivation of cyclin D3 in mice causes an increased frequency of αß T cells that express TCRß proteins from both alleles, producing lymphocytes of heterogeneous specificities. To determine how cyclin D3 enforces monogenic TCRß expression, we used our mouse lines with enhanced rearrangement of specific Vß segments due to replacement of their poor-quality recombination signal sequence (RSS) DNA elements with a better RSS. We show that cyclin D3 inactivation in these mice elevates the frequencies of αß T cells that display proteins from RSS-augmented Vß segments on both alleles. By assaying mature αß T cells, we find that cyclin D3 deficiency increases the levels of Vß rearrangements that occur within developing thymocytes. Our data demonstrate that a component of the cell cycle machinery mediates TCRß protein-signaled feedback inhibition in thymocytes to achieve monogenic TCRß expression and resulting uniform specificity of individual αß T cells.

Targeting diacylglycerol kinase α impairs lung tumorigenesis by inhibiting cyclin D3.

BACKGROUND: Diacylglycerol kinase α (DGKA) is the first member discovered from the diacylglycerol kinase family, and it has been linked to the progression of various types of tumors. However, it is unclear whether DGKA is linked to the development of lung cancer. METHODS: We investigated the levels of DGKA in the lung cancer tissues. Cell growth assay, colony formation assay and EdU assay were used to examine the effects of DGKA-targeted siRNAs/shRNAs/drugs on the proliferation of lung cancer cells in vitro. Xenograft mouse model was used to investigate the role of DGKA inhibitor ritanserin on the proliferation of lung cancer cells in vivo. The downstream target of DGKA in lung tumorigenesis was identified by RNA sequencing. RESULTS: DGKA is upregulated in the lung cancer cells. Functional assays and xenograft mouse model indicated that the proliferation ability of lung cancer cells was impaired after inhibiting DGKA. And cyclin D3(CCND3) is the downstream target of DGKA promoting lung cancer. CONCLUSIONS: Our study demonstrated that DGKA promotes lung tumorigenesis by regulating the CCND3 expression and hence it can be considered as a potential molecular biomarker to evaluate the prognosis of lung cancer patients. What's more, we also demonstrated the efficacy of ritanserin as a promising new medication for treating lung cancer.

A rapidly growing cutaneous malignant glomus tumor with a CCND3 mutation.

Glomus tumors are rare mesenchymal neoplasms composed of cells resembling the glomus body. They are most frequently seen in subungual regions but have been reported to arise in almost every anatomic location. Malignant glomus tumors, also called glomangiosarcomas, of cutaneous origin are exceedingly rare with only 47 reported cases. The genetic alterations that lead to the development of cutaneous malignant glomus tumors are not well understood. Small studies report glomus tumors with mutations in glomulin (GLMN), NF1, BRAF, NOTCH, PDGFRB, KRAS, and SMARCB1. These mutations have mostly been studied in deep or visceral glomus tumors. We report a case of a cutaneous malignant glomus tumor with a CCND3 point mutation identified on next generation sequencing, without any of the previously described genetic mutations. CCND3 mutations that cause cyclin D3 amplification may prove to be targets for CDK4/6 inhibitors in the treatment of malignant glomus tumors.

[LncRNA RPL22P1-201 affects prostate cancer cell proliferation, cell cycle, and sensitivity to docetaxel by regulating miR-216b-5p expression].

OBJECTIVE: Exploring the effects and mechanisms of long non coding RNA (lncRNA) RPL22P1-201 on prostate cancer cell proliferation, cell cycle, and docetaxel sensitivity by regulating miR-216b-5p expression. METHODS: The Cancer LncRNA Census database was used to analyze the differential expression of RPL22P1-201 between prostate cancer tissue and normal tissue. Real time quantitative polymerase chain reaction (qRT-PCR) was used to detect the expression level of RPL22P1-201 in prostate cancer cell lines (DU-145, C4-2B, PC3, 22Rv1, LNCaP) and normal prostate epithelial cells (RWPE-1). PC3 cells were divided into si-RPL22P1-201 group (transfected with RPL22P1-201 interference sequence) and si-NC group (transfected with si-NC sequence). Colony formation assay was used to detect the proliferation ability of PC3 cells. Flow cytometry was used to detect the PC3 cell cycle. The CCK-8 method was used to detect the proliferation of PC3 cells in each group after treatment with docetaxel. The dual luciferase reporter gene experiment verifies the binding of RPL22P1-201 to the target gene. qRT-PCR was used to detect the expression level of miR-216b-5p. Western blot was used to detect the expression levels of TrkB, CDK4, cyclin D2, cyclin D3, and CDK6 proteins. RESULTS: The expression level of RPL22P1-201 in prostate cancer tissue was higher than that in normal tissue (P<0.01). The expression level of RPL22P1-201 in prostate cancer cell lines was higher than that in normal prostate epithelial cells (P<0.01). The number of colonies in the si-NC group and si-RPL22P1-201 group was (256.1 ± 28.79) and (78.77 ± 14.52), respectively. The difference was statistically significant (P<0.01). The G0/G1 cell rates in the si-NC group and si-RPL22P1-201 group were (43.18 ± 4.56)% and (68.85 ± 3.40)%, respectively. The S cell rates were (36.84 ± 2.28)% and (24.27 ± 2.74)%, respectively. The G2/M cell rates were (19.98 ± 2.69)% and (6.88 ± 1.57)%, respectively, and the differences were statistically significant (all P<0.05). The cell survival rate of the si-RPL22P1-201 group under the action of docetaxel was lower than that of the si-NC group (all P<0.05). RPL22P1-201 can pair and bind with miR-216b-5p (P<0.01). Compared with the si-NC group, the si-RPL22P1-201 group showed a decrease in miR-216b-5p expression in PC3 cells (P<0.01), and a decrease in TrkB, CDK4, cyclin D2, cyclin D3, and CDK6 protein expression. CONCLUSIONS: RPL22P1-201 is highly expressed in prostate cancer, and silencing RPL22P1-201 inhibits prostate cancer PC3 cell proliferation and cell cycle by increasing miR-216b-5p expression, and enhances PC3 cell sensitivity to docetaxel.

Upregulation of KIF18B facilitates malignant phenotype of esophageal squamous cell carcinoma by activating CDCA8/mTORC1 pathway.

BACKGROUND: Kinesin family member 18B (KIF18B) has been regarded as an oncogene that is abnormally overexpressed in some cancers, but its mechanism in esophageal squamous cell carcinoma (ESCC) remains unclear, which is thereby investigated in this study. METHODS: Bioinformatics analysis was performed to analyze the expression of KIF18B in esophageal carcinoma (ESCA). Quantitative real-time polymerase chain reaction (qRT-PCR) was used to detect KIF18B expression in ESCC cells. After KIF18B overexpression or cell division cycle associated 8 (CDCA8) deficiency, ESCC cells were subjected to determination of qRT-PCR, Western blot, cell counting kit-8 assay, flow cytometry, wound healing, and Transwell assay. The mechanism of KIF18B in the mechanistic target of rapamycin complex 1 (mTORC1) pathway was detected by Western blot. RESULTS: KIF18B was overexpressed in ESCA samples and ESCC cells. Upregulation of KIF18B enhanced the viability, accelerated cell cycle by elevating CDK4 and Cyclin D3 levels as well as promoted the migration and invasion by decreasing E-cadherin level and increasing Vimentin and N-cadherin levels in ESCC cells, which was counteracted by CDCA8 silencing. The expression of CDCA8 in ESCC cells was upregulated by KIF18B overexpression. KIF18B overexpression activated the mTORC1 pathway by upregulating phosphorylated (p)-/p70S6K and p-/mTOR levels in the ESCC cells, which was reversed by CDCA8 silencing. CONCLUSION: KIF18B overexpression promotes the proliferation, migration, and invasion of ESCC cells via CDCA8-mediated mTORC1 signaling pathway in vitro.

Long Noncoding RNA LOC554202 Predicts a Poor Prognosis and Correlates with Immune Infiltration in Thyroid Cancer.

Thyroid cancer (TC) is one of the widely diagnosed carcinomas in women before the age of 30. Nevertheless, there is currently a lack of specific biomarkers for predicting the prognosis of TC. Long noncoding RNAs (lncRNAs) were important regulators in human cancer progression as previously described. Unfortunately, there is little known on these lncRNAs' functions and molecular mechanisms in TC. In our literature, we found that LOC554202 (MIR31HG) was upregulated in TC samples and correlated with clinicopathological features, including M stage, N stage, and lymph nodes examined status in TC. In addition, we found that LOC554202 overexpression was evidently correlated with high immune infiltrate levels of CD8+ T cells, macrophage, neutrophil, myeloid dendritic cells, and B cells in TC. Knockdown of LOC554202 impeded TC cell proliferation and cycle progression. We found that LOC554202 had an association with metabolic pathways, vesicle-mediated transport, tricarboxylic acid cycle, Hedgehog signaling pathway, and Hippo signaling pathway in TC. Reducing LOC554202 hindered TC cell proliferation and cycle progression. Finally, we found that LOC554202 participated in modulating the expression of the regulators of Hippo signaling and TCA pathway, such as CCND2, CCND3, SDHC, SDHD, SUCLA2, and SUCLG1. We thought that this study would largely enhance our understanding of LOC554202's functional roles in human TC progression and immune response.

Recurrent Mutations in Cyclin D3 Confer Clinical Resistance to FLT3 Inhibitors in Acute Myeloid Leukemia.

PURPOSE: Biomarkers of response and resistance to FLT3 tyrosine kinase inhibitors (TKI) are still emerging, and optimal clinical combinations remain unclear. The purpose of this study is to identify co-occurring mutations that influence clinical response to the novel FLT3 inhibitor pexidartinib (PLX3397). EXPERIMENTAL DESIGN: We performed targeted sequencing of pretreatment blasts from 29 patients with FLT3 internal tandem duplication (ITD) mutations treated on the phase I/II trial of pexidartinib in relapsed/refractory FLT3-ITD+ acute myeloid leukemia (AML). We sequenced 37 samples from 29 patients with available material, including 8 responders and 21 non-responders treated at or above the recommended phase II dose of 3,000 mg. RESULTS: Consistent with other studies, we identified mutations in NRAS, TP53, IDH2, and a variety of epigenetic and transcriptional regulators only in non-responders. Among the most frequently mutated genes in non-responders was Cyclin D3 (CCND3). A total of 3 individual mutations in CCND3 (Q276*, S264R, and T283A) were identified in 2 of 21 non-responders (one patient had both Q276* and S264R). No CCND3 mutations were found in pexidartinib responders. Expression of the Q276* and T283A mutations in FLT3-ITD MV4;11 cells conferred resistance to apoptosis, decreased cell-cycle arrest, and increased proliferation in the presence of pexidartinib and other FLT3 inhibitors. Inhibition of CDK4/6 activity in CCND3 mutant MV4;11 cells restored pexidartinib-induced cell-cycle arrest but not apoptosis. CONCLUSIONS: Mutations in CCND3, a gene not commonly mutated in AML, are a novel cause of clinical primary resistance to FLT3 inhibitors in AML and may have sensitivity to CDK4/6 inhibition.

Overexpression Populus d-Type Cyclin Gene PsnCYCD1;1 Influences Cell Division and Produces Curved Leaf in Arabidopsis thaliana.

d-type cyclins (CYCDs) are a special class of cyclins and play extremely important roles in plant growth and development. In the plant kingdom, most of the existing studies on CYCDs have been done on herbaceous plants, with few on perennial woody plants. Here, we identified a Populus d-type cyclin gene, PsnCYCD1;1, which is mainly transcribed in leaf buds and stems. The promoter of PsnCYCD1;1 activated GUS gene expression and transgenic Arabidopsis lines were strongly GUS stained in whole seedlings and mature anthers. Moreover, subcellular localization analysis showed the fluorescence signal of PsnCYCD1;1-GFP fusion protein is present in the nucleus. Furthermore, overexpression of the PsnCYCD1;1 gene in Arabidopsis can promote cell division and lead to small cell generation and cytokinin response, resulting in curved leaves and twisted inflorescence stems. Moreover, the transcriptional levels of endogenous genes, such as ASs, KNATs, EXP10, and PHB, were upregulated by PsnCYCD1;1. Together, our results indicated that PsnCYCD1;1 participates in cell division by cytokinin response, providing new information on controlling plant architecture in woody plants.

The Polycomb group protein MEDEA controls cell proliferation and embryonic patterning in Arabidopsis.

Establishing the embryonic body plan of multicellular organisms relies on precisely orchestrated cell divisions coupled with pattern formation, which, in animals, are regulated by Polycomb group (PcG) proteins. The conserved Polycomb Repressive Complex 2 (PRC2) mediates H3K27 trimethylation and comes in different flavors in Arabidopsis. The PRC2 catalytic subunit MEDEA is required for seed development; however, a role for PRC2 in embryonic patterning has been dismissed. Here, we demonstrate that embryos derived from medea eggs abort because MEDEA is required for patterning and cell lineage determination in the early embryo. Similar to PcG proteins in mammals, MEDEA regulates embryonic patterning and growth by controlling cell-cycle progression through repression of CYCD1;1, which encodes a core cell-cycle component. Thus, Arabidopsis embryogenesis is epigenetically regulated by PcG proteins, revealing that the PRC2-dependent modulation of cell-cycle progression was independently recruited to control embryonic cell proliferation and patterning in animals and plants.

The pathologic diagnosis of mantle cell lymphoma.

Mantle cell lymphoma (MCL) is a mature B-cell non-Hodgkin lymphoma usually characterized by t(11;14) (q13;q32), or CCND1 translocation and Cyclin D1 over expression. A very small subset of MCL may lack the t(11;14) (q13;q32) translocation and Cyclin D1 over expression, but show alternative translocations involving CCND2 and CCND3, and over expression of SOX11. In general, MCL has been considered a very aggressive and incurable lymphoma and patients with MCL usually have a poor prognosis. However, indolent variants, including in situ mantle cell neoplasm and the recently recognized leukemic non-nodal MCL do exist. In recent years, genome-wide molecular genetic studies have revealed a characteristic MCL genetic profile. This review will focus on the pathologic diagnosis of MCL using the traditional morphological and immunophenotypic strategies combined with cytogenetic characteristics and recently identified molecular profile. Morphological subtypes, immunophenotypic variants, recently recognized indolent variants, as well as MCL risk stratification will also be discussed.

CircMYLK promotes the growth, migration, invasion, and survival of bladder cancer cells by upregulating CCND3 level via competitively binding to miR-34a.

Bladder cancer is one of the most common types of urothelial carcinoma with a rising incidence rate worldwide. Circular RNAs (circRNAs) are involved in the development of numerous cancers, including bladder cancer. We aimed to uncover the role and associated mechanism of circMYLK in bladder cancer. The expression levels of circMYLK, miRNA-34a (miR-34a) and Cyclin D3 (CCND3) mRNA were investigated using real-time quantitative polymerase chain reaction. The protein level of CCND3 was investigated using western blot. In functional assays, flow cytometry assays were utilized for cell cycle analysis and cell apoptosis analysis. Transwell assays were used for cell migration and invasion analysis. Caspase-3 activity was examined to monitor cell apoptosis. The putative relationship between miR-34a and circMYLK or CCND3 was validated by dual-luciferase reporter assay and RNA immunoprecipitation assay. CircMYLK was highly expressed in bladder cancer tissues and cells. CircMYLK downregulation inhibited bladder cancer cell migration and invasion, and promoted cancer cell apoptosis and cell cycle arrest. MiR-34a, a target of circMYLK, was downregulated in bladder cancer tissues and cells. MiR-34a inhibition reversed the effects of circMYLK downregulation and then recovered bladder cell malignant behaviors. Further analysis showed that CCND3 was a downstream target of miR-34a, and CCND3 was upregulated in bladder cancer tissues and cells. MiR-34a overexpression blocked bladder cancer cell migration and invasion, and induced cell apoptosis and cycle arrest, while these effects were abolished by CCND3 overexpression. CircMYLK contributed to the malignant development of bladder cancer cells partly through the miR-34a/CCND3 regulatory network, showing the significance of circMYLK in bladder cancer pathogenesis.

CDK11 Promotes Cytokine-Induced Apoptosis in Pancreatic Beta Cells Independently of Glucose Concentration and Is Regulated by Inflammation in the NOD Mouse Model.

Background: Pancreatic islets are exposed to strong pro-apoptotic stimuli: inflammation and hyperglycemia, during the progression of the autoimmune diabetes (T1D). We found that the Cdk11(Cyclin Dependent Kinase 11) is downregulated by inflammation in the T1D prone NOD (non-obese diabetic) mouse model. The aim of this study is to determine the role of CDK11 in the pathogenesis of T1D and to assess the hierarchical relationship between CDK11 and Cyclin D3 in beta cell viability, since Cyclin D3, a natural ligand for CDK11, promotes beta cell viability and fitness in front of glucose. Methods: We studied T1D pathogenesis in NOD mice hemideficient for CDK11 (N-HTZ), and, in N-HTZ deficient for Cyclin D3 (K11HTZ-D3KO), in comparison to their respective controls (N-WT and K11WT-D3KO). Moreover, we exposed pancreatic islets to either pro-inflammatory cytokines in the presence of increasing glucose concentrations, or Thapsigargin, an Endoplasmic Reticulum (ER)-stress inducing agent, and assessed apoptotic events. The expression of key ER-stress markers (Chop, Atf4 and Bip) was also determined. Results: N-HTZ mice were significantly protected against T1D, and NS-HTZ pancreatic islets exhibited an impaired sensitivity to cytokine-induced apoptosis, regardless of glucose concentration. However, thapsigargin-induced apoptosis was not altered. Furthermore, CDK11 hemideficiency did not attenuate the exacerbation of T1D caused by Cyclin D3 deficiency. Conclusions: This study is the first to report that CDK11 is repressed in T1D as a protection mechanism against inflammation-induced apoptosis and suggests that CDK11 lies upstream Cyclin D3 signaling. We unveil the CDK11/Cyclin D3 tandem as a new potential intervention target in T1D.

Overexpression of PtoCYCD3;3 Promotes Growth and Causes Leaf Wrinkle and Branch Appearance in Populus.

D-type cyclin (cyclin D, CYCD), combined with cyclin-dependent kinases (CDKs), participates in the regulation of cell cycle G1/S transition and plays an important role in cell division and proliferation. CYCD could affect the growth and development of herbaceous plants, such as Arabidopsis thaliana, by regulating the cell cycle process. However, its research in wood plants (e.g., poplar) is poor. Phylogenetic analysis showed that in Populus trichocarpa, CYCD3 genes expanded to six members, namely PtCYCD3;1-6. P. tomentosa CYCD3 genes were amplified based on the CDS region of P. trichocarpa CYCD3 genes. PtoCYCD3;3 showed the highest expression in the shoot tip, and the higher expression in young leaves among all members. Therefore, this gene was selected for further study. The overexpression of PtoCYCD3;3 in plants demonstrated obvious morphological changes during the observation period. The leaves became enlarged and wrinkled, the stems thickened and elongated, and multiple branches were formed by the plants. Anatomical study showed that in addition to promoting the differentiation of cambium tissues and the expansion of stem vessel cells, PtoCYCD3;3 facilitated the division of leaf adaxial epidermal cells and palisade tissue cells. Yeast two-hybrid experiment exhibited that 12 PtoCDK proteins could interact with PtoCYCD3;3, of which the strongest interaction strength was PtoCDKE;2, whereas the weakest was PtoCDKG;3. Molecular docking experiments further verified the force strength of PtoCDKE;2 and PtoCDKG;3 with PtoCYCD3;3. In summary, these results indicated that the overexpression of PtoCYCD3;3 significantly promoted the vegetative growth of Populus, and PtoCYCD3;3 may interact with different types of CDK proteins to regulate cell cycle processes.

Fbxl8 suppresses lymphoma growth and hematopoietic transformation through degradation of cyclin D3.

Overexpression of D-type cyclins in human cancer frequently occurs as a result of protein stabilization, emphasizing the importance of identification of the machinery that regulates their ubiqutin-dependent degradation. Cyclin D3 is overexpressed in ~50% of Burkitt's lymphoma correlating with a mutation of Thr-283. However, the E3 ligase that regulates phosphorylated cyclin D3 and whether a stabilized, phosphorylation deficient mutant of cyclin D3, has oncogenic activity are undefined. We describe the identification of SCF-Fbxl8 as the E3 ligase for Thr-283 phosphorylated cyclin D3. SCF-Fbxl8 poly-ubiquitylates p-Thr-283 cyclin D3 targeting it to the proteasome. Functional investigation demonstrates that Fbxl8 antagonizes cell cycle progression, hematopoietic cell proliferation, and oncogene-induced transformation through degradation of cyclin D3, which is abolished by expression of cyclin D3T283A, a non-phosphorylatable mutant. Clinically, the expression of cyclin D3 is inversely correlated with the expression of Fbxl8 in lymphomas from human patients implicating Fbxl8 functions as a tumor suppressor.

Cyclin D3 drives inertial cell cycling in dark zone germinal center B cells.

During affinity maturation, germinal center (GC) B cells alternate between proliferation and somatic hypermutation in the dark zone (DZ) and affinity-dependent selection in the light zone (LZ). This anatomical segregation imposes that the vigorous proliferation that allows clonal expansion of positively selected GC B cells takes place ostensibly in the absence of the signals that triggered selection in the LZ, as if by "inertia." We find that such inertial cycles specifically require the cell cycle regulator cyclin D3. Cyclin D3 dose-dependently controls the extent to which B cells proliferate in the DZ and is essential for effective clonal expansion of GC B cells in response to strong T follicular helper (Tfh) cell help. Introduction into the Ccnd3 gene of a Burkitt lymphoma-associated gain-of-function mutation (T283A) leads to larger GCs with increased DZ proliferation and, in older mice, clonal B cell lymphoproliferation, suggesting that the DZ inertial cell cycle program can be coopted by B cells undergoing malignant transformation.

Cyclin D3 Governs Clonal Expansion of Dark Zone Germinal Center B Cells.

Germinal center (GC) B cells surge in their proliferative capacity, which poses a direct risk for B cell malignancies. G1- to S-phase transition is dependent on the expression and stability of D-type cyclins. We show that cyclin D3 expression specifically regulates dark zone (DZ) GC B cell proliferation. B cell receptor (BCR) stimulation of GC B cells downregulates cyclin D3 but induces c-Myc, which subsequently requires cyclin D3 to exert GC expansion. Control of DZ proliferation requires degradation of cyclin D3, which is dependent on phosphorylation of residue Thr283 and can be bypassed by cyclin D3T283A hyperstabilization as observed in B cell lymphoma. Thereby, selected GC B cells in the light zone potentially require disengagement from BCR signaling to accumulate cyclin D3 and undergo clonal expansion in the DZ.

Phospholipase C beta1 (PI-PLCbeta1)/Cyclin D3/protein kinase C (PKC) alpha signaling modulation during iron-induced oxidative stress in myelodysplastic syndromes (MDS).

MDS are characterized by anemia and transfusion requirements. Transfused patients frequently show iron overload that negatively affects hematopoiesis. Iron chelation therapy can be effective in these MDS cases, but the molecular consequences of this treatment need to be further investigated. That is why we studied the molecular features of iron effect and Deferasirox therapy on PI-PLCbeta1 inositide signaling, using hematopoietic cells and MDS samples. At baseline, MDS patients showing a positive response after iron chelation therapy displayed higher levels of PI-PLCbeta1/Cyclin D3/PKCalpha expression. During treatment, these responder patients, as well as hematopoietic cells treated with FeCl3 and Deferasirox, showed a specific reduction of PI-PLCbeta1/Cyclin D3/PKCalpha expression, indicating that this signaling pathway is targeted by Deferasirox. The treatment was also able to specifically decrease the production of ROS. This effect correlated with a reduction of IL-1A and IL-2, as well as Akt/mTOR phosphorylation. In contrast, cells exposed only to FeCl3 and cells from MDS patients refractory to Deferasirox showed a specific increase of ROS and PI-PLCbeta1/Cyclin D3/PKCalpha expression. All in all, our data show that PI-PLCbeta1 signaling is a target for iron-induced oxidative stress and suggest that baseline PI-PLCbeta1 quantification could predict iron chelation therapy response in MDS.