Osimertinib Covalently Binds to CD34 and Eliminates Myeloid Leukemia Stem/Progenitor Cells.

Osimertinib is a third-generation covalent EGFR inhibitor that is used in treating non-small cell lung cancer. First-generation EGFR inhibitors were found to elicit pro-differentiation effect on acute myeloid leukemia (AML) cells in preclinical studies, but clinical trials yielded mostly negative results. Here, we report that osimertinib selectively induced apoptosis of CD34+ leukemia stem/progenitor cells but not CD34- cells in EGFR-negative AML and chronic myeloid leukemia (CML). Covalent binding of osimertinib to CD34 at cysteines 199 and 177 and suppression of Src family kinases (SFK) and downstream STAT3 activation contributed to osimertinib-induced cell death. SFK and STAT3 inhibition induced synthetic lethality with osimertinib in primary CD34+ cells. CD34 expression was elevated in AML cells compared with their normal counterparts. Genomic, transcriptomic, and proteomic profiling identified mutation and gene expression signatures of patients with AML with high CD34 expression, and univariate and multivariate analyses indicated the adverse prognostic significance of high expression of CD34. Osimertinib treatment induced responses in AML patient-derived xenograft models that correlated with CD34 expression while sparing normal CD34+ cells. Clinical responses were observed in two patients with CD34high AML who were treated with osimertinib on a compassionate-use basis. These findings reveal the therapeutic potential of osimertinib for treating CD34high AML and CML and describe an EGFR-independent mechanism of osimertinib-induced cell death in myeloid leukemia. SIGNIFICANCE: Osimertinib binds CD34 and selectively kills CD34+ leukemia cells to induce remission in preclinical models and patients with AML with a high percentage of CD34+ blasts, providing therapeutic options for myeloid leukemia patients.

A two-stage genome-wide association study identifies novel germline genetic variations in CACNA2D3 associated with radiotherapy response in nasopharyngeal carcinoma.

BACKGROUND: Radiotherapy (RT) is the standard treatment for nasopharyngeal carcinoma (NPC). However, due to individual differences in radiosensitivity, biomarkers are needed to tailored radiotherapy to cancer patients. However, comprehensive genome-wide radiogenomic studies on them are still lacking. The aim of this study was to identify genetic variants associated with radiotherapy response in patients with NPC. METHODS: This was a large­scale genome-wide association analysis (GWAS) including a total of 981 patients. 319 individuals in the discovery stage were genotyped for 688,783 SNPs using whole genome-wide screening microarray. Significant loci were further genotyped using MassARRAY system and TaqMan SNP assays in the validation stages of 847 patients. This study used logistic regression analysis and multiple bioinformatics tools such as PLINK, LocusZoom, LDBlockShow, GTEx, Pancan-meQTL and FUMA to examine genetic variants associated with radiotherapy efficacy in NPC. RESULTS: After genome-wide level analysis, 19 SNPs entered the validation stage (P < 1 × 10- 6), and rs11130424 ultimately showed statistical significance among these SNPs. The efficacy was better in minor allele carriers of rs11130424 than in major allele carriers. Further stratified analysis showed that the association existed in patients in the EBV-positive, smoking, and late-stage (III and IV) subgroups and in patients who underwent both concurrent chemoradiotherapy and induction/adjuvant chemotherapy. CONCLUSION: Our study showed that rs11130424 in the CACNA2D3 gene was associated with sensitivity to radiotherapy in NPC patients. TRIAL REGISTRATION NUMBER: Effect of genetic polymorphism on nasopharyngeal carcinoma chemoradiotherapy reaction, ChiCTR-OPC-14005257, Registered 18 September 2014, http://www.chictr.org.cn/showproj.aspx?proj=9546 .

C1Q labels a highly aggressive macrophage-like leukemia population indicating extramedullary infiltration and relapse.

Extramedullary infiltration (EMI) is a concomitant manifestation that may indicate poor outcome of acute myeloid leukemia (AML). The underlying mechanism remains poorly understood and therapeutic options are limited. Here, we employed single-cell RNA sequencing on bone marrow (BM) and EMI samples from a patient with AML presenting pervasive leukemia cutis. A complement C1Q+ macrophage-like leukemia subset, which was enriched within cutis and existed in BM before EMI manifestations, was identified and further verified in multiple patients with AML. Genomic and transcriptional profiling disclosed mutation and gene expression signatures of patients with EMI that expressed high levels of C1Q. RNA sequencing and quantitative proteomic analysis revealed expression dynamics of C1Q from primary to relapse. Univariate and multivariate analysis demonstrated adverse prognosis significance of C1Q expression. Mechanistically, C1Q expression, which was modulated by transcription factor MAF BZIP transcription factor B, endowed leukemia cells with tissue infiltration ability, which could establish prominent cutaneous or gastrointestinal EMI nodules in patient-derived xenograft and cell line-derived xenograft models. Fibroblasts attracted migration of the C1Q+ leukemia cells through C1Q-globular C1Q receptor recognition and subsequent stimulation of transforming growth factor ß1. This cell-to-cell communication also contributed to survival of C1Q+ leukemia cells under chemotherapy stress. Thus, C1Q served as a marker for AML with adverse prognosis, orchestrating cancer infiltration pathways through communicating with fibroblasts and represents a compelling therapeutic target for EMI.

Mitochondrial oxidative phosphorylation is dispensable for survival of CD34+ chronic myeloid leukemia stem and progenitor cells.

Chronic myeloid leukemia (CML) are initiated and sustained by self-renewing malignant CD34+ stem cells. Extensive efforts have been made to reveal the metabolic signature of the leukemia stem/progenitor cells in genomic, transcriptomic, and metabolomic studies. However, very little proteomic investigation has been conducted and the mechanism regarding at what level the metabolic program was rewired remains poorly understood. Here, using label-free quantitative proteomic profiling, we compared the signature of CD34+ stem/progenitor cells collected from CML individuals with that of healthy donors and observed significant changes in the abundance of enzymes associated with aerobic central carbonate metabolic pathways. Specifically, CML stem/progenitor cells expressed increased tricarboxylic acid cycle (TCA) with decreased glycolytic proteins, accompanying by increased oxidative phosphorylation (OXPHOS) and decreased glycolysis activity. Administration of the well-known OXPHOS inhibitor metformin eradicated CML stem/progenitor cells and re-sensitized CD34+ CML cells to imatinib in vitro and in patient-derived tumor xenograft murine model. However, different from normal CD34+ cells, the abundance and activity of OXPHOS protein were both unexpectedly elevated with endoplasmic reticulum stress induced by metformin in CML CD34+ cells. The four major aberrantly expressed protein sets, in contrast, were downregulated by metformin in CML CD34+ cells. These data challenged the dependency of OXPHOS for CML CD34+ cell survival and underlined the novel mechanism of metformin. More importantly, it suggested a strong rationale for the use of tyrosine kinase inhibitors in combination with metformin in treating CML.

HE4 and eIF3a Expression Correlates with Surgical Outcome and Overall Survival in Ovarian Cancer Patients with Secondary Cytoreduction.

For recurrent ovarian cancer (ROC), secondary cytoreductive surgery (SCS) is recommended as one optional treatment. However, little is known about the expression and clinical significance of biomarkers during SCS. Human epididymis protein 4 (HE4) is a clinical biomarker for ovarian cancer. Eukaryotic translation initiation factor 3a (eIF3a) is investigated extensively as a potential biomarker for malignancy. The purpose of this study was to investigate the expressions of HE4 and eIF3a at SCS, as well as their associations with surgical outcome and survival in ROC patients. Immunohistochemistry was performed to determine the expressions of HE4 and eIF3a in ovarian tumors taken from both initial and secondary cytoreductive surgery of 35 ROC patients. eIF3a levels were significantly increased at SCS, compared to those at initial cytoreductive surgery (ICS), while HE4 levels were similar. Both HE4 and eIF3a expressions were associated with surgical outcome, in terms of residual tumor. For ICS, patients with high HE4 expression achieved a higher incidence of optimal cytoreduction than those with low HE4 expression (81.0% vs. 33.3%, P = 0.015). A similar result happened in SCS, indicated by higher incidence of no residual tumor in patients with high HE4 expression (76.4% vs. 44.4%, P = 0.046). And high HE4 expression at SCS was more likely to enhance surgical outcome of SCS (77.8% vs. 29.4%, P = 0.038). Therefore, high HE4 expression at either surgery is a predictor of better overall survival (OS) (P = 0.011 and 0.002). Furthermore, patients with an elevated total score (TS) of HE4 between the two surgeries tended to have prolonged OS, compared to those with a non-elevated TS of HE4 (P = 0.076). For eIF3a, initial eIF3a expression was associated with secondary residual tumor (P = 0.035), and the difference in eIF3a expression between the two surgeries correlated with OS (P = 0.052). The expressions of HE4 and eIF3a in tumor specimens correlated with surgical outcome and predicted OS in ROC patients with SCS, thus meriting further investigation.

Downregulation of RIF1 Enhances Sensitivity to Platinum-Based Chemotherapy in Epithelial Ovarian Cancer (EOC) by Regulating Nucleotide Excision Repair (NER) Pathway.

BACKGROUND/AIMS: Rap1 interacting factor 1 (RIF1) was deemed to be involved in replication timing regulation and DNA damage response. However, little is known about the role of RIF1 in malignancies. Thus, this study aimed to investigate whether the expression of RIF1 is relevant to the response of epithelial ovarian cancer (EOC) patients to cisplatin chemotherapy and its underlying mechanism. METHODS: Immunohistochemistry was used for detecting the expression of RIF1 in 72 human ovarian cancer tissues followed by association analysis of RIF1 expression with patients' responses to platinum-based chemotherapy. The survival analysis of ovarian patients based on platinum chemotherapy was analyzed using online databases. RNA interference of RIF1 was carried out in OVCAR3 and A2780 cell lines, to determine the effect of lacking RIF1 expression on cellular responses to cisplatin by using MTS assay. The nucleotide excision repair (NER) capacity of these cells was assessed by using host-cell reactivation and UV sensitivity assay. Western Blot analysis was carried out to determine the effect of RIF1 on the proteins of NER and apoptosis signaling pathway by using RIF1 knockdown cells. BALB/c nude mice model was used for detection of response to cisplatin in vivo. RESULTS: RIF1 expression was significantly associated with the response of ovarian patients to platinum-based chemotherapy (P< 0.01). In cohorts from online databases, high expression of RIF1 was associated with higher mortality of EOC patients based on platinum chemotherapy (P < 0.01). RIF1 knockdown increased sensitivity to cisplatin in EOC in vitro and in vivo. Deletion of RIF1 impaired the NER activity by inhibiting the NER proteins in ovarian cancer cells. Besides, knockdown of RIF1 enhanced cisplatin-induced apoptosis. CONCLUSIONS: RIF1 plays an important role in regulating the expression of NER proteins, which in turn contributes to cellular response to cisplatin and EOC patients' response to platinum-based chemotherapy. RIF1 knockdown also promotes cisplatin-induced apoptosis. RIF1 may serve as a novel biomarker for predicting platinum-based chemosensitivity and the prognosis of EOC patients.

Increased HE4 mRNA Expression Correlates with High Level Of eIF3a mRNA And Better Survival in Women with Epithelial Ovarian Cancer.

Human epididymis protein 4 (HE4) is one of the most promising biomarkers for epithelial ovarian cancer (EOC). The majority of previous studies utilized the serum level or tissue protein expression of HE4 based upon immunohistochemistry (IHC) to evaluate the role of HE4 in the diagnosis, prognosis, and surveillance of EOC, but very little is known about HE4 mRNA expression. Eukaryotic translation initiation factor 3a (eIF3a) is implicated in oncogenesis and has been investigated extensively as a potential biomarker for malignancy. We previously reported a positive correlation between IHC expressions of eIF3a and HE4 in EOC. In the present study, we performed RT-PCR to determine mRNA expressions of HE4 and eIF3a in 30 normal ovarian tissues, 45 benign, 20 borderline and 94 malignant ovarian tumors. The association of HE4 and eIF3a mRNA expressions with clinicopathological characteristics and patient survivals was investigated. IHC was also performed in the same participants to investigate the correlation between mRNA and protein levels of HE4. HE4 mRNA level was found to be 48.42 ± 74.55 (mean ± SD, range: 0.01-343.99), significantly higher in primary EOC than in the borderline tumor, benign tumor, and normal ovarian tissue (P<0.001). The cutoff value was 13.99 for HE4 to discriminate malignant from benign tumors at 68.1% sensitivity and 93.0% specificity. By Spearman's correlation test, HE4 mRNA expression was indicated to positively correlate with serum CA125 level (r=0.530, P<0.001). Higher HE4 mRNA expression was associated with decreased frequency of lymph node metastasis (P=0.038) and better overall survival (OS) (P=0.007) in primary EOC. Multivariable analysis showed an independent prognostic value of the relative mRNA level of HE4 greater than one for OS (Hazard Ratio, 0.069, 95%CI, 0.009-0.530, P=0.010). eIF3a mRNA expression in women with primary EOC was 0.95 ± 1.19 (mean ± SD, range: 0.06-7.46), which was in a positive linear correlation with HE4 mRNA expression (r=0.310, P=0.002). In the present study, the HE4 mRNA level was unparalleled with IHC expression of HE4 (P>0.05). Collectively, our study revealed that increased HE4 mRNA expression correlates with high level of eIF3a mRNA and better survival in women with EOC, which calls for further investigations.

CD44v6 promotes ß-catenin and TGF-ß expression, inducing aggression in ovarian cancer cells.

A high expression of CD44v6 has been reported in numerous malignant cancers, including stomach, prostate, lung and colon. However, the pathological role and the regulatory mechanisms of CD44v6 have yet to be elucidated. In the present study, the expression levels of CD44v6 were shown to be significantly higher in ovarian cancer tissues, as compared with adjacent normal tissues. Furthermore, the upregulated expression levels of CD44v6 were correlated with disease recurrence and poor survival in patients. The expression of CD44v6 was knocked down in the CAOV3 ovarian cell line, by transfection of a specific small hairpin RNA. The present study showed a correlation between the aggression, viability, invasion and migration of the ovarian cancer cells, with the expression of CD44v6. In addition, the expression of CD44v6 was positively correlated with the expression levels of ß­catenin and tumor growth factor­ß, which indicates that the effects of CD44v6 on ovarian cancer cell aggression may be mediated by these two signaling pathways. In conclusion, the present study provides a novel insight into the association between CD44v6 expression and ovarian cancer. CD44v6 may provide a novel target for the prognosis and treatment of ovarian cancer.

TRPM7 is required for ovarian cancer cell growth, migration and invasion.

Our previous study demonstrated that the melastatin-related transient receptor potential channel 7 (TRPM7) was highly expressed in ovarian carcinomas and its overexpression was significantly associated with poor prognosis in ovarian cancer patients. However, the function of TRPM7 in ovarian cancer is mostly unknown. In this study, we examined the roles of TRPM7 in ovarian cancer cell proliferation, migration and invasion. We found that short hairpin RNA interference-mediated silence of TRPM7 significantly inhibited cell proliferation, colony formation, migration and invasion in multiple ovarian cancer cell lines. Mechanistic investigation revealed that silence of TRPM7 decreased phosphorylation levels of Akt, Src and p38 and increased filamentous actin and focal adhesion number in ovarian cancer cells. Thus, our results suggest that TRPM7 is required for proliferation, migration and invasion of ovarian cancer cells through regulating multiple signaling transduction pathways and the formation of focal adhesions.

Overexpression of TRPM7 is associated with poor prognosis in human ovarian carcinoma.

BACKGROUND: The melastatin-related transient receptor potential 7 channel (TRPM7) is a nonselective cation channel that has been shown to promote tumor metastasis and progression. In this study, we determined the expression of TRPM7 in ovarian carcinomas and investigated its possible prognostic value. MATERIALS AND METHODS: Samples were collected from 138 patients with ovarian cancer. Expression of TRPM7 was assessed by real-time PCR and immunohistochemistry, expressed with reference to an established scoring system and related to clinical pathological factors. Kaplan-Meier survival analysis was applied to estimate disease-free survival (DFS) and overall survival (OS). Univariate and multivariate cox regression analyses were performed to correlate TRPM7 expression levels with DFS and OS. RESULTS: TRPM7 was highly expressed in ovarian carcinoma and significantly associated with decreased disease-free survival (DFS: median 20 months vs. 42 months, P=0.0002) and overall survival (OS: median 27 months vs. 46 months, P<0.001). CONCLUSION: Overexpression of TRPM7 expression is significantly associated with poor prognosis in patients with ovarian cancer.

Validation of a liquid chromatography-electrospray ionization-tandem mass spectrometry method for determination of all-trans retinoic acid in human plasma and its application to a bioequivalence study.

A sensitive, reliable and specific LC-MS-MS method was developed and validated for the identification and quantitation of all-trans retinoic acid (ATRA) in human plasma. Acitretin was used as the internal standard (IS). After liquid-liquid extraction of 500 µL plasma with methyl tert-butyl ether (MTBE), ATRA and the IS were chromatographed on a HyPURITY C18 column (150 mm×2.1 mm, 5 µm) with the column temperature set at 40 °C. The mobile phase was consisted of 40% phase A (MTBE-methanol-acetic acid, 50:50:0.5, v/v) and 60% phase B (water-methanol-acetic acid, 50:50:0.5, v/v) with a flow rate of 0.3 mL/min. The API 4000 triple quadrupole mass spectrometer was operated in multiple reaction monitoring (MRM) mode via the positive electrospray ionization interface using the transition m/z 301.4→123.1 for ATRA and m/z 326.9→177.1 for IS, respectively. The calibration curve was linear over the range of 0.45-217.00 ng/mL (r≥0.999) with a lower limit of quantitation (LLOQ) of 0.45 ng/mL. The intra- and inter-day precisions values were below 8% relative standard deviation and the accuracy was from 98.98% to 106.19% in terms of relative error. The validated method was successfully applied in a bioequivalence study of ATRA in Chinese healthy volunteers.