Retinoblastoma Protein Expression Research Articles

An E7-retinoblastoma protein pathway mechanism may account for the higher carcinogenic ability of HPV16 over HPV58 in cervical cancer.

Among human papillomavirus (HPV) type, HPV16 displays the strongest carcinogenic capacity for cervical cancer, but the mechanism underlying this phenomenon remains unclear. We investigated the effect and the underlying mechanism of HPV16 on higher carcinogenic capacity than HPV58. We collected 4,030 cervical exfoliated cell samples for genotyping HPV using HybriBio's proprietary flow-through hybridization technique, liquid-based cytology (LBC), colposcopy, and biopsies if indicated. Four plasmids containing E6 and E7 of HPV16 and 58 were constructed and transfected into 293T and U2OS cells. We detected the cell phenotype using Cell Counting Kit 8 (CCK8) assay, Transwell assay, flow cytometry, and apoptosis assay; the expression of retinoblastoma protein (Rb) and phosphorylated Rb (pRb) was determined via Western blot; and the cell activity was determined via a zebrafish model treated with or without roscovitine. The positive rates of HPV16 and 58 were, respectively, 18.9% and 19.7% in the ≤ low-grade squamous intraepithelial lesion (LSIL) group, 49.5% and 19.6% (P<0.001) in the high-grade squamous intraepithelial lesion (HSIL) group, 65.3% and 9.0% (P<0.001) in the cancer group. In vitro, both 293T and U2OS cells with overexpressed HPV16 E6 and E7 displayed significantly higher cell proliferation, faster cell invasion, decreased cell apoptosis, and accelerated cell cycle from G1 phase to S phase compared to those with overexpressed HPV58 E6 and E7 (all P values <0.05). Rb loss of function was observed in cells with HPV16 E7 overexpression, while a greater level of phosphorylated Rb was observed in cells with HPV58 E7 overexpression. Roscovitine restored Rb expression and decreased the cell activity in zebrafish. HPV16 possesses a stronger carcinogenic ability than does HPV 58, and the mechanism underlying this effect may be the impairment of the E7-Rb pathway.

Antitumor activity of extracellular signal-regulated kinases 1/2 inhibitor BVD-523 (ulixertinib) on thyroid cancer cells.

This study aimed to investigate BVD-523 (ulixertinib), an adenosine triphosphate (ATP)-dependent extracellular signal-regulated kinases 1/2 inhibitor, for its antitumor potential in thyroid cancer. Ten thyroid cancer cell lines known to carry mitogen-activated protein kinase (MAPK)-activated mutations, including v-Raf murine sarcoma viral oncogene homolog B (BRAF) and rat sarcoma virus (RAS) mutations, were examined. Cells were exposed to a 10-fold concentration gradient ranging from 0 to 3000 nM for 5 days. The half-inhibitory concentration was determined using the Cell Counting Kit-8 assay. Following BVD-523 treatment, cell cycle analysis was conducted using flow cytometry. In addition, the impact of BVD-523 on extracellular signal-regulated kinase (ERK)- dependent ribosomal S6 kinase (RSK) activation and the expression of cell cycle markers were assessed through western blot analysis. BVD-523 significantly inhibited thyroid cancer cell proliferation and induced G1/S cell cycle arrest dose-dependently. Notably, cell lines carrying MAPK mutations, especially those with the BRAF V600E mutation, exhibited heightened sensitivity to BVD-523's antitumor effects. Furthermore, BVD-523 suppressed cyclin D1 and phosphorylated retinoblastoma protein expression, and it robustly increased p27 levels in an RSK-independent manner. This study reveals the potent antitumor activity of BVD-523 against thyroid cancer cells bearing MAPK-activating mutations, offering promise for treating aggressive forms of thyroid cancer.

Chondrolipoma of the Breast: A Myofibroblastoma Variant or a Distinct Lesion?

The entity commonly referred to as chondrolipoma is a rare and enigmatic breast lesion with unclear histogenesis and a complete lack of molecular characterization. It is uncertain whether it represents a hamartoma, choristoma, or a distinct neoplasm, including possibly a variant of mammary-type myofibroblastoma. We report two additional chondrolipomatous lesions of the breast. The lesions had varying histologic and immunohistochemical features similar to myofibroblastoma, including the loss of retinoblastoma (Rb) protein expression in one lesion. Molecular analysis by chromosomal microarray analysis performed on a second lesion did not demonstrate a loss of 13q14 or 16q typical of myofibroblastoma. Our findings further support the concept that at least a subset of breast lesions that historically have been classified as chondrolipoma are related to myofibroblastoma. However, the lack of myofibroblastoma-specific molecular alterations in one lesion suggests chondrolipomas may also have varying origins.

Prognostic and Clinicopathological Significance of the Loss of Expression of Retinoblastoma Protein (pRb) in Oral Squamous Cell Carcinoma: A Systematic Review and Meta-Analysis

This systematic review and meta-analysis aims to evaluate the scientific evidence on the implications of retinoblastoma protein (pRb) alterations in oral cancer, in order to determine its prognostic and clinicopathological significance. PubMed, Embase, Web of Science, and Scopus were searched for studies published before February 2022, with no restrictions by publication date or language. The quality of the studies using the Quality in Prognosis Studies tool (QUIPS tool). Meta-analysis was conducted to achieve the proposed objectives, as well as heterogeneity, subgroup, meta-regression, and small study-effects analyses. Twenty studies that met the inclusion criteria (2451 patients) were systematically reviewed and meta-analyzed. Our results were significant for the association between the loss of pRb expression and a better overall survival (HR = 0.79, 95%CI = 0.64–0.98, p = 0.03), whereas no significant results were found for disease-free survival or clinico-pathological parameters (T/N status, clinical stage, histological grade). In conclusion, our evidence-based results demonstrate that loss of pRb function is a factor associated with improved survival in patients with OSCC. Research lines that should be developed in the future are highlighted.

Carrier-free nanomedicines self-assembled from palbociclib dimers and Ce6 for enhanced combined chemo-photodynamic therapy of breast cancer.

Palbociclib is the world's first CDK4/6 kinase inhibitor to be marketed. However, it is not effective in the treatment of triple negative breast cancer (TNBC) due to the loss of retinoblastoma protein expression. Thus, combinatorial chemotherapy is indispensable for TNBC treatment. Herein, a carrier-free nanomedicine self-assembled from palbociclib dimers and Ce6 for enhanced combined chemo-photodynamic therapy of breast cancer is reported. The dimeric prodrug (Palb-TK-Palb) was synthesized by conjugating two palbociclib molecules to the connecting skeleton containing a ROS-responsive cleavable thioketal bond. The Palb-TK-Palb/Ce6 NP co-delivery nanoplatform was prepared through the self-assembly of Palb-TK-Palb, Ce6 and DSPE-PEG2000. This novel carrier-free formulation as an efficient therapeutic agent showed efficient therapeutic agent loading capacity, high cellular uptake and huge therapeutic performance against breast cancer cells. The results of in vitro antitumor activity and cell apoptosis demonstrated that Palb-TK-Palb/Ce6 NPs presented a better inhibitory effect on the growth of cancer cells due to the palbociclib and Ce6 co-delivery nanomedicine-mediated synergistic chemo-photodynamic therapy. The IC50 values of Palb-TK-Palb/Ce6 NPs in MDA-MB-231 cells were around 1-2 μM and 2 μM and the Palb-TK-Palb/Ce6 NPs showed an increase in apoptosis up to 91.9%. In general, the carrier-free nanomedicine self-assembled from palbociclib dimers and Ce6 provides options for combinatorial chemo-photodynamic therapy.

Correlation Between E6 and E7 Oncogene Mutation Human Papilloma Virus High Risk Type 16 with Retinoblastoma Protein Expression in Cervical Cancer

Introduction: The E6 and E7 oncoproteins of high-risk Human Papillomavirus (HPV) have crucial roles in cervical cancer pathogenesis by inhibiting p53 and retinoblastoma protein (pRb) which are tumor suppressor genes. Genetic sequence mutations of E6 and E7 oncogenes can affect E6/E7 protein functions that will change E7-pRB interaction. Furthermore, this condition will influence progression cervical cancer progression in several intratypic variants of high-risk HPV type 16. Methods: A cross-sectional study was conducted from September 2020-September 2021, at the Obstetrics and Gynecology Outpatient Clinic, Prof Dr I. G. N. G. Ngoerah General Hospital. Consecutive sampling was taken by collecting cervical cancer tissue followed by isolation, amplification, and gene sequencing to assess E6 and E7 mutations. The expression of pRb was measured by immunohistochemical staining (IHC). Results: From 100 cervical cancer subjects, 31 subjects were found HPV16 positive (19 wildtype and 12 mutants). The proportion of E6 and E7 mutants was 25.8% and 12.9% respectively. This study shows that T27C/F9F; A360G/E120E and G371A/R124K variants were found on E6 oncogene mutations, meanwhile, A86C/N29T; A86G/N29S; C229T/R77C and T285C/S95S variants were detected on E7 oncogene mutations. The types of E6 mutations were T27C (16.1%), A360G (6.4%) and G371A (1 subject; 3.2%). In addition, pRb expression was stronger in mutant group than wild-type group 60.5% vs. 53%. There was no correlation between retinoblastoma protein expression and mutations E6/E7 oncogene HPV Type 16 (PR 0.22; 95% CI 0.03-1.6; p value 0.10). Conclusions: In cervical cancer, there is no significant difference between the expression of retinoblastoma protein in mutant vs wildtype E6 and E7 oncogene HPV16.

Nuclear Beclin 1 Destabilizes Retinoblastoma Protein to Promote Cell Cycle Progression and Colorectal Cancer Growth.

Simple SummaryThe role of autophagy core-protein Beclin 1 in colorectal cancer (CRC) development remains controversial. Here, we show that nuclear Beclin 1 is up-regulated in CRC with a negative correlation to RB protein expression. Silencing of BECN1 up-regulates RB expression resulting in cell cycle G1 arrest and inhibition of xenograft tumor growth independent of p53. Ablation of BECN1 facilitates MDM2–MDMX complex formation to promote MDMX polyubiquitination and degradation, consequently leading to RB protein stabilization. These results reveal that nuclear Beclin 1 can promote CRC growth through modulation of RB protein stability and imply that nuclear Beclin 1 may be a prognostic indicator in human colorectal cancer.Autophagy is elevated in colorectal cancer (CRC) and is generally associated with poor prognosis. However, the role of autophagy core-protein Beclin 1 remains controversial in CRC development. Here, we show that the expression of nuclear Beclin 1 protein is upregulated in CRC with a negative correlation to retinoblastoma (RB) protein expression. Silencing of BECN1 upregulates RB resulting in cell cycle G1 arrest and growth inhibition of CRC cells independent of p53. Furthermore, ablation of BECN1 inhibits xenograft tumor growth through elevated RB expression and reduced autophagy, while simultaneous silencing of RB1 restores tumor growth but has little effect on autophagy. Mechanistically, knockdown of BECN1 promotes the complex formation of MDM2 and MDMX, resulting in MDM2-dependent MDMX instability and RB stabilization. Our results demonstrate that nuclear Beclin 1 can promote cell cycle progression through modulation of the MDM2/X-RB pathway and suggest that Beclin 1 promotes CRC development by facilitating both cell cycle progression and autophagy.

Targeting the Retinoblastoma/E2F repressive complex by CDK4/6 inhibitors amplifies oncolytic potency of an oncolytic adenovirus

CDK4/6 inhibitors (CDK4/6i) and oncolytic viruses are promising therapeutic agents for the treatment of various cancers. As single agents, CDK4/6 inhibitors that are approved for the treatment of breast cancer in combination with endocrine therapy cause G1 cell cycle arrest, whereas adenoviruses induce progression into S-phase in infected cells as an integral part of the their life cycle. Both CDK4/6 inhibitors and adenovirus replication target the Retinoblastoma protein albeit for different purposes. Here we show that in combination CDK4/6 inhibitors potentiate the anti-tumor effect of the oncolytic adenovirus XVir-N-31 in bladder cancer and murine Ewing sarcoma xenograft models. This increase in oncolytic potency correlates with an increase in virus-producing cancer cells, enhanced viral genome replication, particle formation and consequently cancer cell killing. The molecular mechanism that regulates this response is fundamentally based on the reduction of Retinoblastoma protein expression levels by CDK4/6 inhibitors.

Poly-2-oxazoline nanoparticles potentiate effectiveness of vismodegib for breast cancer through improvement in pharmacokinetics and reduction in systemic toxicity

Breast cancer is one of the most significant health challenges in the world. Vismodegib has been used for treatment of breast cancer limits the prescriptions of this drug. Therefore, it is of great significance to improve therapeutic effect of vismodegib therapy. This study modified the vismodegib with poly-2-oxazoline (POx) nanoparticles (POx-vismo) and examined the therapeutic potential of this approach for treating breast cancer. After preparation of POx-vismo micelles, they were characterized and loading efficiency, which was also measured by high performance liquid chromatography. The POx-vismo and vismodegib were administered to mice with breast cancer and healthy, respectively. Tumor, forebrain and blood samples were taken for analysis of pharmacokinetics and measurement of toxicity, where the concentration of POx was determined. Pharmacodynamic response was evaluated and Western blot analysis was used to determine the expression of retinoblastoma protein (pRB) and proliferating cell nuclear antigen (PCNA). Compared with traditional vismodegib, POx-vismo significantly improved the delivery efficiency of drugs in central nervous system accompanied with higher level of vismodegib. Administration with POx-vismo greatly improved the pharmacokinetics, diminished the toxicity, and strengthened the efficacy. POx-vismo therapy more effectively suppressed tumor cell growth and decreased pRB expression than oral administration of vismodegib. Collectively, the POx effectively served as a carrier of vismodegib in breast cancer and brain. POx-vismo micelles suppressed breast cell growth with low toxicity and addition of POx can enhance the efficacy of vismodegib for breast cancer and improves pharmacokinetics and pharmacodynamic response. These findings provide a novel insight into the drug therapy against the disorder.

Steroid glycosides isolated from Paris polyphylla var. chinensis aerial parts and paris saponin II induces G1/S-phase MCF-7 cell cycle arrest

In our previous research on Vietnamese medicinal plants, we found that the ethanolic extract of the aerial parts of Paris polyphylla var. chinensis exhibited cytotoxic effects in vitro in the MCF-7 human cancer cell line. Here, we used combined chromatographic separations to isolate six compounds including a new steroid glycoside, paripoloside A (3), and five known compounds, from the butanol extract of the aerial parts of P. polyphylla. We unambiguously elucidated their structures based on spectroscopic data (proton and carbon-13 nuclear magnetic resonance, heteronuclear single quantum coherence, heteronuclear multiple bond correlation, correlation spectroscopy, and high-resolution electrospray ionization mass spectroscopy data), and chemical reactions. Among the isolated compounds, paris saponin II (PSII) had the strongest cytotoxic effects against MCF-7 breast cancer cells. Interestingly, PSII significantly increased the expression of p53, p21, p27, and Bax protein levels and significantly suppressed the expression of cyclin D1 and retinoblastoma protein. These data suggest that PSII may induce G1/S phase cell cycle arrest and apoptosis pathway development in MCF-7 cells. Furthermore, the MCF-7 breast cancer cells mechanism of PSII was also investigated using molecular docking. Together, our results demonstrate that isolated compounds from P. polyphylla are promising candidates as breast cancer inhibitors.

Cellular angiofibroma arising in the anorectal region: clinicopathologic and immunohistochemical analysis of five cases

Cellular angiofibroma (CA) is a rare, benign mesenchymal tumor with a predilection to the distal female and male genital tract. Extragenital examples of CA, including anorectal CAs, are exceedingly rare and documented mainly as single case reports. Herein, we analyze the clinicopathological and immunohistochemical features of 5 anorectal CAs. There were 4 males and one female ranging in age from 45 to 70 (median, 58) years at the time of surgery. Tumors arose in the superficial tissues of the anorectal (n=3) and perianal (n=2) regions. The tumors were well circumscribed ranging from 2 to 6.7 (median, 5.4) cm. All demonstrated a low to moderately cellular proliferation of cytologically bland spindled cells within a variably dense collagenous and focally myxocollagenous stroma and small- to medium-sized vessels featuring perivascular collagen deposition. Two cases showed degenerative and/or inflammatory changes. All 5 tumors strongly expressed CD34 and androgen receptor proteins, more variably expressed estrogen (n=5) and progesterone (n=4) receptor proteins and desmin (n=3), and focally expressed alpha-smooth muscle actin (n=3), GATA-3 (n=2), and p16 (n=1). Retinoblastoma protein expression was reduced (n=4) (compared with expression in endothelial cells) or completely lost (n=1). All patients were treated with simple surgical excision, and the 2 study members with follow-up data showed no evidence of local recurrence over a postoperative follow-up interval of 23 and 73 months. In comparison with conventional genital tract CA, our 5 anorectal CAs occurred mostly in males, were generally less cellular, and appear to follow a similar uneventful clinical course.

Exosomes of Adipose-derived Stem Cells Conditioned Media Promotes Retinoblastoma and Forkhead-Box M1 Protein Expression

BACKGROUND: In the senescence process, the retinoblastoma (Rb) protein binds to E2F in hypophosphorylated conditions, preventing the cell to enter the S-phase in the cell cycle. Human Forkhead Box M1 (FOXM1) protein, key regulator G1/S and G2/M phases, decreases in the senescence process. Many studies have been carried out to reverse this system, one of which used exosomes of adipose-derived stem c ells conditioned media (ADSC-CM). These exosomes contain a variety of specific proteins which have pro-proliferation properties, however, little is known on the role of these exosomes toward the change of phosphorylated Rb and FOXM1. AIM: This study aims to find out the involvement of exosomes of ADSC-CM on these two proteins on senescence human dermal fibroblasts (HDFs). METHODS: In vitro experiment was undergone randomization sample and non-blinded pre-/post-test control group. The primary culture of senescent HDFs was transfected with exosomes of ADSC-CM; then, its effect on migration and senescence reversal was observed through analyzing Sa-β-gal, Rb, and FOXM1 protein expression. RESULTS: The expression of Sa-β-gal was higher in the control group. Our result demonstrated the exosome of ADSC-CM significantly induced the expression of Rb and FOXM1 protein in senescent HDFs (p &lt; 0.05). CONCLUSION: It proved that exosomes of ADSC-CM could shift the senescent fibroblast into metabolically active cells.

Molecular classification of a complex structural rearrangement of the RB1 locus in an infant with sporadic, isolated, intracranial, sellar region retinoblastoma

Retinoblastoma is a childhood cancer of the retina involving germline or somatic alterations of the RB Transcriptional Corepressor 1 gene, RB1. Rare cases of sellar-suprasellar region retinoblastoma without evidence of ocular or pineal tumors have been described. A nine-month-old male presented with a sellar-suprasellar region mass. Histopathology showed an embryonal tumor with focal Flexner-Wintersteiner-like rosettes and loss of retinoblastoma protein (RB1) expression by immunohistochemistry. DNA array-based methylation profiling confidently classified the tumor as pineoblastoma group A/intracranial retinoblastoma. The patient was subsequently enrolled on an institutional translational cancer research protocol and underwent comprehensive molecular profiling, including paired tumor/normal exome and genome sequencing and RNA-sequencing of the tumor. Additionally, Pacific Biosciences (PacBio) Single Molecule Real Time (SMRT) sequencing was performed from comparator normal and disease-involved tissue to resolve complex structural variations. RNA-sequencing revealed multiple fusions clustered within 13q14.1-q21.3, including a novel in-frame fusion of RB1-SIAH3 predicted to prematurely truncate the RB1 protein. SMRT sequencing revealed a complex structural rearrangement spanning 13q14.11-q31.3, including two somatic structural variants within intron 17 of RB1. These events corresponded to the RB1-SIAH3 fusion and a novel RB1 rearrangement expected to correlate with the complete absence of RB1 protein expression. Comprehensive molecular analysis, including DNA array-based methylation profiling and sequencing-based methodologies, were critical for classification and understanding the complex mechanism of RB1 inactivation in this diagnostically challenging tumor.

A report of a patient presenting with three metachronous 13q14LOH mesenchymal tumours: spindle cell lipoma, cellular angiofibroma and mammary myofibroblastoma

Spindle cell lipoma, cellular angiofibroma and mammary myofibroblastoma are mesenchymal tumours that have overlapping morphological and immunophenotypic features. Aberrations in chromosome 13q14 have been identified as a recurrent feature. We report a unique case of a 69-year-old woman who metachronously developed all three tumours. She developed a peri-urethral and a recurrent peri-vaginal cellular angiofibroma at age 54 and 57, respectively, a spindle cell lipoma at age 62 and a mammary myofibroblastoma at age 69. Dual-colour interphase fluorescent in situ hybridisation (FISH) revealed losses of RB1 and FOXO1 (13q14LOH [loss of heterozygosity]) within neoplastic cells. There was also loss of retinoblastoma (Rb) protein expression. To our knowledge, this is the first report of these three tumours arising in the same patient. The genetic link between these tumours supports the hypothesis that they may arise from the same progenitor cells. However, further research is required to elucidate the precise pathogenetic link.

Adverse Clinical Outcome in Hodgkin's Disease Is Associated With Loss of Retinoblastoma Protein Expression, High Ki67 Proliferation Index, and Absence of Epstein-Barr Virus-Latent Membrane Protein 1 Expression

AbstractPrevious studies have shown that in non-Hodgkin's lymphomas and others neoplasms, tumoral progression, treatment response, and outcome are related to the expression of different oncogenic and tumor suppressor proteins. This study aimed to determine the prognostic significance of the expression of p53, bcl2, retinoblastoma protein (Rb), Ki67, CD15, and latent membrane protein 1-Epstein–Barr Virus (LMP1-EBV) proteins in Hodgkin's disease. A retrospective study was performed on 140 patients collected at the 11 participating centers belonging to the Spanish Collaborative Group for the Study of Hodgkin's Disease. A highly sensitive immunohistochemical method with previous microwave-induced antigen retrieval technique was used for the demonstration of the above-mentioned proteins. A Cox's multivariate analysis was performed to evaluate the impact of the variables in the overall survival, together with a logistic regression model for the achievement of complete remission. Univariate statistical analysis confirmed the prognostic significance of the alredy known clinical parameters: stage, age over 60 years, and B symptoms. High proliferation index (Ki67) and loss of Rb expression were also found to be adverse prognostic factors influencing respectively lower overall survival and failure to achieve complete remission. Multivariate analysis confirmed the independent significance of these two parameters and additionally identifies LMP1-EBV expression as a favorable prognostic marker, in relation with overall survival. Histopathological type, p53, bcl2, and CD15 expression lack significant influence on the outcome of this series. The progression of the disease or the response to treatment in HD patients is the consequence of the interrelationship of different factors, among which LMP1 expression, loss of Rb, and high growth fraction seems to play a more relevant role.

Programmed cell death protein 1/programmed death ligand 1 but not HER2 is a potential therapeutic target in gastric neuroendocrine carcinoma.

Gastric neuroendocrine carcinoma (NEC) is a rare and aggressive subtype with a poor prognosis. We aim to investigate expression profiles of HER2 and programmed death ligand 1 (PD-L1) in gastric NEC to test the potential applicability of drugs targeting these molecules. Expression levels of HER2 and PD-L1 were evaluated in 25 gastric NECs, including 10 pure NECs and 15 mixed adenocarcinoma-NECs, and a combined positive score (CPS) was used to evaluate PD-L1 expression. The correlations of expression levels with both clinicopathological features and the expression of p53, retinoblastoma protein (Rb) and mismatch repair proteins were also analysed. Eighteen of the 25 (72%) cases showed a PD-L1 CPS of≥1, which was previously shown to be associated with response to pembrolizumab. Positive nodal metastasis and low tumour-infiltrating lymphocyte (TIL) levels at the invasive margin were significantly associated with a PD-L1 CPS of<1. The NEC component was HER2-negative in all cases, whereas HER2 positivity was observed in the adenocarcinoma component of six of 15 (40%) mixed adenocarcinoma-NECs. Mismatch repair deficiency, a mutant pattern of p53 expression and loss of Rb expression were observed in four (16%), 17 (68%) and nine (36%) cases, respectively, although these alterations were not associated with the PD-L1 CPS or other clinicopathological characteristics. HER2 is unlikely to be an effective target in gastric NEC owing to the lack of HER2 expression, whereas the PD-1/PD-L1 pathway is a potential therapeutic target for gastric NEC because of the relatively high prevalence of a PD-L1 CPS of≥1 in this subtype.

The role of CUDC-907, a dual phosphoinositide-3 kinase and histone deacetylase inhibitor, in inhibiting proliferation of adult T-cell leukemia.

New effective therapeutic strategies for human T-cell leukemia virus type 1 (HTLV-1)-driven adult T-cell leukemia (ATL) are required because of resistance to chemotherapeutic agents. Here, we aimed to determine the therapeutic efficacy of a dual phosphoinositide 3 kinase (PI3K)/histone deacetylase (HDAC) inhibitor, CUDC-907. Cell viability, cell cycle progression, and apoptotic events were examined by WST-8 assay, flow cytometry, and Hoechst 33342 staining. Caspase activity was determined using Calorimetric Caspase Assay kits. Immunoblotting and electrophoretic mobility shift assay were used to assess the intracellular signaling cascades. The combination of PI3K inhibitor BKM120 and HDAC inhibitor LBH589 resulted in a synergistic cytotoxic effect in HTLV-1-infected T cells. CUDC-907 was more efficacious than BKM120 and LBH589. It induced G1 cell cycle arrest with downregulation of cyclin D1/D2, CDK4/6, c-Myc, and phosphorylated retinoblastoma protein expression. Apoptosis was induced via caspase-3/8/9 activation along with downregulation of Bcl-XL , Bcl-2, XIAP, survivin, and cIAP1/2, and upregulation of Bax and Bak. Histone H3 acetylation, H2AX activation, Hsp27 phosphorylation, and Hsp70 and Hsp27 upregulation were observed after treatment. CUDC-907 suppressed Akt, NF-κB, and AP-1 by downregulating phosphorylated and/or total Akt, IKKα/β, RelA, JunB, and JunD. CUDC-907 may be a potential therapeutic agent for ATL.

Retinoblastoma protein expression and its predictors in triple-negative breast cancer

Retinoblastoma protein (Rb) is a product of the RB tumor suppressor gene. Its expression is highly prevalent in luminal breast cancers and is critical to the success of cyclin-dependent kinase (CDK) 4/6 inhibitor therapy. Expression of Rb in triple-negative breast cancer (TNBC), tumors generally associated with basal biology, is not well known. However, heterogeneity among TNBC and presence of subtypes with luminal features are well described. The purpose of this study was to determine prevalence and predictors of Rb protein expression in BRCA1-associated and sporadic TNBCs. We studied 180 TNBC patients (70 BRCA1-associated and 110 sporadic). The clinical and pathologic features of these cases were previously assessed and reported. For this study, immunohistochemical stains for Rb were performed on tissue microarray sections. Details of treatment and outcome were abstracted from medical records. Fifty-one percent of TNBC were Rb positive (≥10% nuclei staining), and 85% of these cases had ≥50% nuclei staining. Rb expression was significantly associated with sporadic TNBC (71.4% vs 49.4%; p < 0.001), androgen receptor (AR) expression (16.5% vs 3.4%; p = 0.007), histologic grade 1 or 2 (9.9% vs 2.2%; p = 0.04), and first recurrence in bone (8.8% vs 1.1%; p = 0.03). Expression of p53 was not associated with Rb expression. Expression of Rb in TNBC was significantly associated with sporadic TNBC, AR expression, lower histologic grade, and metastasis to bone. These observations characterize a TNBC subtype with features suggestive of luminal-like biology and the potential to benefit from CDK 4/6 inhibition.

Salinomycin and its derivatives as potent RET transcriptional inhibitors for the treatment of medullary thyroid carcinoma (MTC).

Rearranged during transfection kinase (RET) is a validated molecular target in medullary thyroid cancer (MTC), as activating mutations in RET are often associated with the development of MTC. The present study reports the first preclinical characterization of salinomycin and selected analogs as potent RET transcriptional inhibitors. Reverse transcription‐PCR and immunoblotting revealed that salinomycin profoundly decreased RET expression in the TT human MTC cell line by inhibiting RET transcription. Moreover, salinomycin resulted in remarkable anti‐proliferative activity against MTC that is driven by RET (gain of function mutation) by selectively inhibiting the intracellular PI3K/Akt/mTOR signaling pathway. Also, flow cytometry and fluorescence‐activated cell sorting showed that salinomycin induces G1 phase arrest and apoptosis by reducing the expression of retinoblastoma protein, E2F1, cyclin D and CDK4. The structure‐activity relationship of salinomycin was investigated in this study. Some of the salinomycin derivatives showed the ability to reduce RET expression where others fail to alter RET expression. These results suggest that the RET‐suppressing effect of salinomycin may be largely attributed to disruption of the Wnt pathway, presumably through interference with the ternary LRP6‐Frizzled‐Wnt complex. Furthermore, these findings support the further preclinical evaluation of salinomycin and its analogs as a promising new class of therapeutic agents for the improved treatment of MTCSupport or Funding InformationAmerican Cancer Society for their support of this study (grant no. RSGM‐12‐046‐01‐CDD).

Cytotoxic Effect of Geranylphenol Derivatives in the Human Breast Cancer Cell Line MDA-MB-231 and Gastric Cancer Cell Line MKN74

Background: Previous studies have demonstrated that geranyl metabolites, found mainly in marine organisms, exhibit interesting antimicrobial and antifungal activities. In addition, linear geranyl derivatives have been synthesized as drugs and reported cytotoxic and anticancer activities.&#x0D; Aims: Considering the biological testing and the structural features of these compounds, we evaluated seven linear geranylphenol derivatives on the human breast cancer cell line MDA-MB-231, and the human gastric cancer cell line MKN74.&#x0D; Results: We found that compounds 2, 5 and 7 were cytotoxic for both cancer cell lines. From them, the most potent was compound 2, with an IC50=7.5 μM for MKN74 cells, and compound 7, with an IC50=14.73 μM for MDA-MB-231 cells. By nuclear staining and inmunocytochemistry, we detected that the three compounds induced cell death, and by Western blot analysis, we observed a remarkable decrease in the expression of cyclin D1 and the retinoblastoma protein, key regulators of the cell cycle.&#x0D; Conclusion: Considering that compounds 2 and 7 were the most potent compounds inducing cell death, and were able to decrease the expression of retinoblastoma protein and cyclin D1, proteins usually altered in different types of cancers, they appear as promising therapeutic agents against cancer.&#x0D; Bangladesh Journal of Medical Science Vol.19(3) 2020 p.486-500