Immune infiltration, aggressive pathology, and poor survival outcomes in RECQL helicase deficient breast cancers.

RECQL is essential for genomic stability. Here, we evaluated RECQL in 449 pure ductal carcinomas in situ (DCIS), 152 DCIS components of mixed DCIS/invasive breast cancer (IBC) tumors, 157 IBC components of mixed DCIS/IBC and 50 normal epithelial terminal ductal lobular units (TDLUs). In 726 IBCs, CD8+, FOXP3+, IL17+, PDL1+, PD1+ T-cell infiltration (TILs) were investigated in RECQL deficient and proficient cancers. Tumor mutation burden (TMB) was evaluated in five RECQL germ-line mutation carriers with IBC by genome sequencing. Compared with normal epithelial cells, a striking reduction in nuclear RECQL in DCIS was evident with aggressive pathology and poor survival. In RECQL deficient IBCs, CD8+, FOXP3+, IL17+ or PDL1+ TILs were linked with aggressive pathology and shorter survival. In germline RECQL mutation carriers, increased TMB was observed in 4/5 tumors. We conclude that RECQL loss is an early event in breast cancer and promote immune cell infiltration.

Hyaline cell-rich chondroid syringoma: A potential pitfall on cytology.

Chondroid syringoma is a rare adnexal tumor of skin, with few cases diagnosed on fine needle aspiration cytology (FNAC). Hyaline cell-rich chondroid syringoma (HCRCS) is a very uncommon variant of chondroid syringoma described in histopathologic studies. This variant differs from the usual chondroid syringoma in its site of presentation, cytohistologic features, and morphologically mimics malignant neoplasms. To the best of our knowledge, cytologic features of this entity have never been described. This case report highlights some unusual features of this tumor and discusses the cytologic features of HCRCS along with neoplastic mimics.

Endothelial Specific Deletion of Autotaxin Improves Stroke Outcomes.

Autotaxin (ATX) is an extracellular secretory enzyme (lysophospholipase D) that catalyzes the hydrolysis of lysophosphatidyl choline to lysophosphatidic acid (LPA). The ATX-LPA axis is a well-known pathological mediator of liver fibrosis, metastasis in cancer, pulmonary fibrosis, atherosclerosis, and neurodegenerative diseases. Additionally, it is believed that LPA may cause vascular permeability. In ischemic stroke, vascular permeability leading to hemorrhagic transformation is a major limitation for therapies and an obstacle to stroke management. Therefore, in this study, we generated an endothelial-specific ATX deletion in mice (ERT2 ATX-/-) to observe stroke outcomes in a mouse stroke model to analyze the role of endothelial ATX. The AR2 probe and Evans Blue staining were used to perform the ATX activity and vascular permeability assays, respectively. Laser speckle imaging was used to observe the cerebral blood flow following stroke. In this study, we observed that stroke outcomes were alleviated with the endothelial deletion of ATX. Permeability and infarct volume were reduced in ERT2 ATX-/- mice compared to ischemia-reperfusion (I/R)-only mice. In addition, the cerebral blood flow was retained in ERT2 ATX-/- compared to I/R mice. The outcomes in the stroke model are alleviated due to the limited LPA concentration, reduced ATX concentration, and ATX activity in ERT2 ATX-/- mice. This study suggests that endothelial-specific ATX leads to increased LPA in the brain vasculature following ischemic-reperfusion and ultimately disrupts vascular permeability, resulting in adverse stroke outcomes.

Alteration of Cellular Energy Metabolism through LPAR2-Axin2 Axis in Gastric Cancer.

Lysophosphatidic acid (LPA), a multifunctional endogenous phospholipid, plays a vital role in cellular homeostasis and the malignant behavior of cancer cells through G-protein-coupled receptors. However, the role of LPA in ß-catenin-mediated gastric cancer is unknown. Here, we have noted the high expression of LPAR2 in human gastric cancer tissues, and that LPA treatment significantly increased the proliferation, migration, and invasion of human gastric cancer cells. Results from our biochemical experiments showed that an LPA exposure increased the expression of ß-catenin and its nuclear localization, increased the phosphorylation of glycogen synthase kinase 3ß (GSK-3ß), decreased the expression of Axin2, and increased the expression of the target genes of the ß-catenin signaling pathway. The LPA2 receptor (LPAR2) antagonist significantly reduced the LPA-induced nuclear localization of ß-catenin, the primary signaling event. The knockdown of LPAR2 in the gastric cancer cell lines robustly reduced the LPA-induced ß-catenin activity. An LPA exposure increased the ATP production by both oxidative phosphorylation and glycolysis, and this effect was abrogated with the addition of an LPAR2 antagonist and XAV393, which stabilizes the Axin and inhibits the ß-catenin signaling pathway. Based on our findings, the possibility that LPA contributes to gastric cancer initiation and progression through the ß-catenin signaling pathway as well as by the dysregulation of the energy metabolism via the LPAR2 receptor and Axin2, respectively, provides a novel insight into the mechanism of and possible therapeutic targets of gastric cancer.

Electrophilic Aldehyde 4-Hydroxy-2-Nonenal Mediated Signaling and Mitochondrial Dysfunction.

Reactive oxygen species (ROS), a by-product of aerobic life, are highly reactive molecules with unpaired electrons. The excess of ROS leads to oxidative stress, instigating the peroxidation of polyunsaturated fatty acids (PUFA) in the lipid membrane through a free radical chain reaction and the formation of the most bioactive aldehyde, known as 4-hydroxynonenal (4-HNE). 4-HNE functions as a signaling molecule and toxic product and acts mainly by forming covalent adducts with nucleophilic functional groups in proteins, nucleic acids, and lipids. The mitochondria have been implicated as a site for 4-HNE generation and adduction. Several studies clarified how 4-HNE affects the mitochondria's functions, including bioenergetics, calcium homeostasis, and mitochondrial dynamics. Our research group has shown that 4-HNE activates mitochondria apoptosis-inducing factor (AIFM2) translocation and facilitates apoptosis in mice and human heart tissue during anti-cancer treatment. Recently, we demonstrated that a deficiency of SOD2 in the conditional-specific cardiac knockout mouse increases ROS, and subsequent production of 4-HNE inside mitochondria leads to the adduction of several mitochondrial respiratory chain complex proteins. Moreover, we highlighted the physiological functions of HNE and discussed their relevance in human pathophysiology and current discoveries concerning 4-HNE effects on mitochondria.

Transcriptional regulation by a RecQ helicase.

RecQ helicases participate in a variety of DNA metabolic processes through their multiple biochemical activities. In vitro characterization and cellular studies have suggested that RECQ1 (also known as RECQL or RECQL1) performs its diverse functions through specific interactions with DNA and protein partners. We have taken an unbiased approach to determine the contribution of RECQ1 in genome maintenance and as a putative susceptibility factor in breast cancer. Here, we provide methodology to map the genome-wide binding sites of RECQ1 together with the profiling of RECQ1-dependent transcriptome to investigate its role in gene regulation. The described approach will be helpful to develop a mechanistic framework for elucidating critical functions of RECQ1 and other RecQ homologs in distinct chromatin and biological contexts.

High Expression of RECQL Protein in ER-Positive Breast Tumours Is Associated With a Better Survival.

Background: RECQL (also known as RECQ1 and RECQL1) is a gene of recent interest in breast cancer and an association between high levels of RECQL protein in breast cancer tumour cells and good survival of patients has been reported. Methods: To validate this association, we measured the RECQL protein levels in tumours of 933 breast cancer patients using immunohistochemistry analysis and followed the patients for death from breast cancer. Results: Women with a level of RECQL protein above the 75th percentile had better 15-year disease-specific survival among ER-positive patients (62.5% vs. 48.7%, HR= 0.72, 95%CI= 0.52-0.98, p-value = 0.04), but not among ER- patients (48.9% vs. 48.0%, HR= 1.07, 95%CI= 0.67-1.69, p-value= 0.79). Among the ER-negative patients, high RECQL protein levels were associated with better survival among women who received tamoxifen treatment (67.0% vs. 51.5%, HR= 0.64, 95%CI= 0.41-0.99, p-value= 0.04). Conclusion: RECQL might be a new predictive marker for tamoxifen treatment among ER-positive patients.

Genome-wide investigations on regulatory functions of RECQ1 helicase.

DNA helicase RECQ1 (also known as RECQL or RECQL1) is a candidate breast cancer susceptibility gene significantly correlated with clinical outcomes of sporadic breast cancer patients. Prior studies have suggested that RECQ1 maintains genomic stability by regulating a wide variety of core cellular functions including DNA replication, DNA damage response, and transcription. However, it is unclear which, if any, of these are the primary functions of RECQ1 as related to its role in suppressing breast cancer. We describe here an unbiased integrative genomics approach that enabled us to discover a previously unknown regulatory role of RECQ1 in promoting Estrogen Receptor alpha (ERα) expression and the expression of specific ERα target genes in ER positive breast cancer cells. We discuss potential future applications of similar experimental strategies in advancing the mechanistic understanding and elucidating specific new details of genome-wide functions of RECQ1 and other RecQ helicases in maintaining genomic stability and preventing cancer.

Cytology of peritoneal implants of borderline serous tumor of ovaries in ascitic fluid.

OBJECTIVES: Peritoneal fluid cytology is done routinely in cases with serous carcinoma of ovary. However, morphologic features of borderline serous tumors (BSTs) of ovary in ascitic fluid have been rarely described. The aim of our study was to evaluate the morphologic features of BST with and without ascitic fluid involvement (BST+ and BST-, respectively) and compare with those of serous carcinomas, both in conventional and liquid-based cytology (LBC) smears. MATERIAL AND METHODS: Out of 30 BST cases reported in 3 years, seven cases had BST+. We compared the cytomorphology of seven cases of BST+, seven cases of BST-, and seven cases of serous adenocarcinoma with positive ascitic fluid cytology. Both conventional and LBC smears were studied in all cases and compared. Histopathology of omentum in these cases was also studied. RESULTS: Most cases with BST+ had regular papillary fragment borders with nuclei showing mild-to-moderate pleomorphism, fine nuclear chromatin with small nucleoli as compared with serous carcinomas all of which had irregular borders with moderate-to-severe nuclear pleomorphism, coarse chromatin, and macronucleoli. CONCLUSION: A combination of cytoarchitectural and nuclear features can help in suspecting BST in ascitic fluid. Ascitic fluid cytology together with tissue histology can increase the rate of the detection of peritoneal implants.

Genome-Wide Analysis Unveils DNA Helicase RECQ1 as a Regulator of Estrogen Response Pathway in Breast Cancer Cells.

Susceptibility to breast cancer is significantly increased in individuals with germ line mutations in RECQ1 (also known as RECQL or RECQL1), a gene encoding a DNA helicase essential for genome maintenance. We previously reported that RECQ1 expression predicts clinical outcomes for sporadic breast cancer patients stratified by estrogen receptor (ER) status. Here, we utilized an unbiased integrative genomics approach to delineate a cross talk between RECQ1 and ERα, a known master regulatory transcription factor in breast cancer. We found that expression of ESR1, the gene encoding ERα, is directly activated by RECQ1. More than 35% of RECQ1 binding sites were cobound by ERα genome-wide. Mechanistically, RECQ1 cooperates with FOXA1, the pioneer transcription factor for ERα, to enhance chromatin accessibility at the ESR1 regulatory regions in a helicase activity-dependent manner. In clinical ERα-positive breast cancers treated with endocrine therapy, high RECQ1 and high FOXA1 coexpressing tumors were associated with better survival. Collectively, these results identify RECQ1 as a novel cofactor for ERα and uncover a previously unknown mechanism by which RECQ1 regulates disease-driving gene expression in ER-positive breast cancer cells.

RECQ1 Helicase in Genomic Stability and Cancer.

RECQ1 (also known as RECQL or RECQL1) belongs to the RecQ family of DNA helicases, members of which are linked with rare genetic diseases of cancer predisposition in humans. RECQ1 is implicated in several cellular processes, including DNA repair, cell cycle and growth, telomere maintenance, and transcription. Earlier studies have demonstrated a unique requirement of RECQ1 in ensuring chromosomal stability and suggested its potential involvement in tumorigenesis. Recent reports have suggested that RECQ1 is a potential breast cancer susceptibility gene, and missense mutations in this gene contribute to familial breast cancer development. Here, we provide a framework for understanding how the genetic or functional loss of RECQ1 might contribute to genomic instability and cancer.

Keratin 19 regulates cell cycle pathway and sensitivity of breast cancer cells to CDK inhibitors.

Keratin 19 (K19) belongs to the keratin family of proteins, which maintains structural integrity of epithelia. In cancer, K19 is highly expressed in several types where it serves as a diagnostic marker. Despite the positive correlation between higher expression of K19 in tumor and worse patient survival, the role of K19 in breast cancer remains unclear. Therefore, we ablated K19 expression in MCF7 breast cancer cells and found that K19 was required for cell proliferation. Transcriptome analyses of KRT19 knockout cells identified defects in cell cycle progression and levels of target genes of E2F1, a key transcriptional factor for the transition into S phase. Furthermore, proper levels of cyclin dependent kinases (CDKs) and cyclins, including D-type cyclins critical for E2F1 activation, were dependent on K19 expression, and K19-cyclin D co-expression was observed in human breast cancer tissues. Importantly, K19 interacts with cyclin D3, and a loss of K19 resulted in decreased protein stability of cyclin D3 and sensitivity of cells towards CDK inhibitor-induced cell death. Overall, these findings reveal a novel function of K19 in the regulation of cell cycle program and suggest that K19 may be used to predict the efficacy of CDK inhibitors for treatments of breast cancer.

The DNA repair helicase RECQ1 has a checkpoint-dependent role in mediating DNA damage responses induced by gemcitabine.

The response of cancer cells to therapeutic drugs that cause DNA damage depends on genes playing a role in DNA repair. RecQ-like helicase 1 (RECQ1), a DNA repair helicase, is critical for genome stability, and loss-of-function mutations in the RECQ1 gene are associated with increased susceptibility to breast cancer. In this study, using a CRISPR/Cas9-edited cell-based model, we show that the genetic or functional loss of RECQ1 sensitizes MDA-MB-231 breast cancer cells to gemcitabine, a nucleoside analog used in chemotherapy for triple-negative breast cancer. RECQ1 loss led to defective ATR Ser/Thr kinase (ATR)/checkpoint kinase 1 (ChK1) activation and greater DNA damage accumulation in response to gemcitabine treatment. Dual deficiency of MUS81 structure-specific endonuclease subunit (MUS81) and RECQ1 increased gemcitabine-induced, replication-associated DNA double-stranded breaks. Consistent with defective checkpoint activation, a ChK1 inhibitor further sensitized RECQ1-deficient cells to gemcitabine and increased cell death. Our results reveal an important role for RECQ1 in controlling cell cycle checkpoint activation in response to gemcitabine-induced replication stress.