The Ca2+ -regulated protein kinase CIPK1 integrates plant responses to phosphate deficiency in Arabidopsis thaliana

Phosphate (Pi) deficiency severely restricts plant growth and development, as Pi is an essential macronutrient. Calcium (Ca²⁺ ) is a ubiquitous second messenger in plants; calcineurin B-like proteins (CBL) and CBL-interacting protein kinases (CIPK) are signalling pathways that act as an important Ca²⁺ signalling network which integrates plants to fine tune the response to stress; however, whether CIPK are involved in Pi deficiency stress remains largely unknown. In this study, we carried out a reverse genetic strategy to screen T-DNA insertion mutants of CIPK isoforms under Pi deficiency in Arabidopsis thaliana. Then Pi content, transcription of phosphate starvation-induced (PSI) genes, acid phosphatase activity and hydrogen peroxide were determined in the wild-type (WT) and cipk1 mutant, respectively. The phenotype of CIPK1 complementation lines was analysed. The cipk1 mutant had a more sensitive phenotype, with lower root elongation and root length, and decreased Pi content compared with the WT under Pi deficiency. Moreover, CIPK1 mutation caused phosphate starvation-induced (PSI) genes to be significantly induced under Pi deficiency. Histological staining demonstrated that the cipk1 mutant had increased acid phosphatase activity and hydrogen peroxide concentration under Pi deficiency. By using the yeast two-hybrid system, we further demonstrated the interaction between CIPK1 and the WRKY transcription factors, WRKY6 and WRKY42. Overall, we demonstrate that CIPK1 is involved in the Pi deficiency signalling pathway in A. thaliana, revealing the important role of Ca²⁺ in the Pi nutrition signalling pathway, and potentially providing a theoretical foundation for molecular breeding of crops with better Pi utilization efficiency.

A Food and Drug Administration analysis of survival outcomes comparing the Adjuvant Paclitaxel and Trastuzumab trial with an external control from historical clinical trials

BACKGROUND

Although the Adjuvant Paclitaxel and Trastuzumab (APT) trial has been adopted clinically, single-arm trials have limitations, and interest remains whether these patients with small node-negative human epidermal growth factor receptor 2 (HER2)-positive early breast cancer (EBC) would benefit from more intensive chemotherapy. This analysis explored whether external controls can contextualize single-arm studies to add to clinical decision making in the use of de-escalated therapy in patients with low-risk HER2-positive EBC.

PATIENTS AND METHODS

Patient-level data from five randomized trials supporting drug approval in adjuvant HER2-positive EBC were pooled, and patients with low-risk EBC were selected (n = 1770). Patients treated concurrently with trastuzumab and either anthracycline/cyclophosphamide/taxane/trastuzumab (ACTH) or taxane/carboplatin/trastuzumab (TCH; n = 1366) were matched (1:1) to patients treated with paclitaxel and trastuzumab (TH) in the APT trial (n = 406) using propensity scores. Patients treated with anthracycline/cyclophosphamide/taxane (ACT; n = 374) were also matched (1:1) to those treated with TH. Propensity scores were estimated using covariates of age, tumor stage, estrogen receptor status, progesterone receptor status, and histological grade.

RESULTS

After matching, the estimated probabilities of invasive disease-free survival (iDFS) at 3 and 5 years were 98.6% and 96.5% in the TH arm, and 96.6% and 92.9% in the ACTH/TCH arm, respectively. The estimated probabilities of overall survival (OS) at 3 and 5 years were 99.7% and 99.3% in the TH arm, and 99.0% and 97.4% in the ACTH/TCH arm, respectively. Comparing the TH arm with the ACT arm in the matched sample, the estimated difference in iDFS was 7.5% (TH 98.8% and ACT 91.3%) at 3 years and 12.6% (TH 96.1% and ACT 83.5%) at 5 years. The estimated difference in OS was 2.6% (TH 100% and ACT 97.4%) at 3 years, and 5.3% (TH 99.3% and ACT 94.0%) at 5 years.

CONCLUSIONS

Our analyses suggest that patients' outcomes in both arms were in general similar, thus providing additional reassurance regarding de-escalation of therapy.

Abstract P4-04-11: A small amount of primary breast cancer shows high tumor mutation burden that may benefit from immune checkpoint inhibitor therapy

Background: Targeted therapy using immune checkpoint inhibitors (ICIs) is a major breakthrough in cancer treatment in the last decade. ICIs like PD1 or PD-L1 antibodies have been shown to be quite effective in cancer like melanoma. However, in most other tumor types including breast cancer, the situation is not as optimistic. Only a small percentage of those patients respond to ICIs therapy. This highlights the importance of identifying biomarkers to predict which patients may benefit from such treatment. Tumor Mutation Burden (TMB) has been shown to be a sensitive marker for ICI treatment. This study is to investigate whether TBM could be used as a biomarker for breast cancer treatment.

Methods: We reviewed next generation sequencing studies of breast cancer. Two such studies with raw data provided were included in our analysis. One study entitled METABRIC performed targeted sequencing of 173 cancer-related genes in around 2500 primary breast cancer tissues. The other study was from TCGA breast cancer project, which performed Whole Exome Sequencing (WES) of around 1000 primary breast cancer samples. Mutation data were downloaded from public data deposit. The number of mutations per sample was calculated. TBM was calculated by divide the coverage in million base pair from that of the total mutation counts.

Results: In METABRIC study, 17272 mutations were identified in 2369 samples, with a median of 7 mutations per sample (95% CI: 6 ˜ 7). The median TMB of METABRIC dataset was 5.8 SNVs/Mb (95% CI: 5 ˜ 5.8). Totally 30 out 2369 (1.3%) samples had a TMB equal or large than 20 SNVs/Mb. In another cohort from TCGA breast cancer study using WES technology, 90172 mutations were identified in 977 samples, with a median of 44 mutations per sample (95% CI: 39 ˜ 50). The median TMB was 1 SNVs/Mb (95% CI: 0.9 ˜ 1.1). Totally 13 out 977 (1.3%) samples had a TMB equal or large than 20 SNVs/Mb.

Conclusions: Breast cancer shows middle to low mutation burden compared to other cancer types. Around 1.3% of breast cancer has quite high TMB of at least 20 SNVs/Mb, which may be qualified for immune checkpoint inhibitors therapy. Our study indicates that TMB may be incorporated as a standard test for late stage breast cancer patients in the clinical practice.

Keywords: Breast cancer, Tumor Mutation Burden, Whole exome sequencing, Targeted sequencing, Immune checkpoint

Citation Format: Wang J, Chen W, Jiang Z, Lin X, Qin T, Yang X, Liu T, Hu H, Li Z, Xie D, Yao H, Song E. A small amount of primary breast cancer shows high tumor mutation burden that may benefit from immune checkpoint inhibitor therapy [abstract]. In: Proceedings of the 2018 San Antonio Breast Cancer Symposium; 2018 Dec 4-8; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2019;79(4 Suppl):Abstract nr P4-04-11.

[A meta-analysis of the effect of occupational exposure to 1-bromopropane on workers' nerve conduction velocity]

Objective: To analysis the occupational exposure to 1-bromopropane on the worker's nerve conduc-tion velocity. Methods: To PubMed, Wanfang, VIP, Chinese Journal Full-text Database (CNKI) and other databases as a data source, searched and screened database to October 2017 on occupational exposure to 1-bromopropane workers on the role of nerve conduction in the paper. According to inclusion and exclusion criteria, we screened literatures, extracted data and evaluated the quality of the included studies, using RevMan5.3 software to test the heterogeneity of the results and us-ing the corresponding mathematical model for data combination analysis. Results: A total of 5 articles were included in the literature. The results showed that the tibial nerve MCV of workers in the 1-bromopropane exposure group was slower than that in the control group (SMD=-0.47,95%CI=-0.70~-0.24) , the difference was statistically significant (Z=4.06, P<0.01). The tibial nerve DL of the exposure group was more prolonged than that of the control group (SMD=0.35,95%CI=0.00~0.69) , with a statistically significant difference (Z=1.99, P=0.05). The sural nerve SCV of the exposure group was slower than that of the control group (SMD=-0.47, 95%CI=-0.78~-0.15), with a statistically significant difference (Z=2.88,P<0.01). Conclusion: Occupational exposure to 1-bromopropane may have an effect on the worker's nerve conduction ve-locity.It's necessary to do broader and deeper neurotoxicity studies about 1-bromopropane.

Detection of carcinoembryonic antigen in peritoneal fluid of patients undergoing laparoscopic distal gastrectomy with complete mesogastric excision

Background

Surgery for gastric cancer may result in free intraperitoneal cancer cells. This study aimed to determine whether laparoscopic gastrectomy with complete mesogastric excision (D2 + CME) reduces the number of free intraperitoneal cancer cells.

Methods

Patients with gastric cancer who had a conventional D2 or D2 + CME laparoscopic distal gastrectomy between April 2015 and February 2017 were included in the study. Intraoperative peritoneal washings were collected before and after tumour resection. Reverse transcriptase–quantitative real-time PCR for carcinoembryonic antigen (CEA) was used to assess the presence of gastric cancer cells.

Results

Eighty-five patients underwent conventional D2 lymphadenectomy and 76 had the D2 + CME procedure. Of 161 peritoneal fluid samples obtained before gastrectomy, 137 (D2, 72; D2 + CME, 65) had low CEA expression indicative of no cancer cells. After gastrectomy, high CEA expression was detected in 23 of the 72 samples (32 per cent) from patients in the D2 group, and in ten of the 65 samples (15 per cent) from the D2 + CME group. In the overall cohort, mean CEA expression level after gastrectomy was lower in the D2 + CME group than in the D2 group (P = 0·0038). In patients with low CEA expression before gastrectomy, disease-free survival in the D2 + CME group was better than that in the D2 group (P = 0·033).

Conclusion

Laparoscopic distal gastrectomy with complete mesogastric excision reduces the number of free intraperitoneal cancer cells and is associated with a better disease-free survival than conventional D2 gastrectomy.

Abstract 4479: Protein arginine methyltransferase PRMT6 regulates cancer stemness through CRAF methylation in hepatocellular carcinoma

Arginine methylation is a post-translational modification that plays pivotal roles in signal transduction and gene transcription during cell fate determination. We found protein methyltransferase 6 (PRMT6) to be frequently down-regulated in hepatocellular carcinoma (HCC) cells and its expression to negatively correlate with aggressive cancer features in HCC patients. Silencing of PRMT6 promoted the tumor-initiating, metastasis and therapy resistance potential of HCC cells. Consistently, loss of PRMT6 expression aggravated liver tumorigenesis in a DEN+CCL4 HCC induced PRMT6-/- mouse model. Integrated transcriptome and protein-protein interaction studies revealed an enrichment of genes implicated in RAS signaling and that PRMT6 interacted with CRAF, and likely other RAF family members, and their methylation at conserved arginine 100, negatively regulating its activity, and as a consequence resulting in enhanced MEK/ERK signaling. Our work uncovered a critical repressive function for PRMT6 in maintenance of HCC cells by regulating the MEK/ERK pathway via arginine methylation of RAF, providing a new avenue of molecular mechanism by which ERK mediated stemness in HCC cells are developed.

Citation Format: LH Chan, L Zhou, Kai Yu Ng, TL Wong, TK Lee, YP Ching, YF Yuan, D Xie, S Richard, MS Huen, XY Guan, S Ma. Protein arginine methyltransferase PRMT6 regulates cancer stemness through CRAF methylation in hepatocellular carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4479.

An antibody-free assay for simultaneous capture and detection of glycoproteins by surface enhanced Raman spectroscopy

A single-step reaction, antibody-free assay for simultaneous capture and detection of glycoproteins by SERS spectroscopy.

Disrupting G6PD-mediated Redox homeostasis enhances chemosensitivity in colorectal cancer

Glucose-6-phosphate dehydrogenase (G6PD) is a key enzyme that generates NADPH to maintain reduced glutathione (GSH), which scavenges reactive oxygen species (ROS) to protect cancer cell from oxidative damage. In this study, we mainly investigate the potential roles of G6PD in colorectal cancer (CRC) development and chemoresistance. We discover that G6PD is overexpressed in CRC cells and patient specimens. High expression of G6PD predicts poor prognosis and correlated with poor outcome of oxaliplatin-based first-line chemotherapy in patients with CRC. Suppressing G6PD decreases NADPH production, lowers GSH levels, impairs the ability to scavenge ROS levels, and enhances oxaliplatin-induced apoptosis in CRC via ROS-mediated damage in vitro. In vivo experiments further shows that silencing G6PD with lentivirus or non-viral gene delivery vector enhances oxaliplatin anti-tumor effects in cell based xenografts and PDX models. In summary, our finding indicated that disrupting G6PD-mediated NADPH homeostasis enhances oxaliplatin-induced apoptosis in CRC through redox modulation. Thus, this study indicates that G6PD is a potential prognostic biomarker and a promising target for CRC therapy.

Meta-analysis comparing denosumab and zoledronic acid for treatment of bone metastases in patients with advanced solid tumours

The purpose of this meta-analysis was to evaluate the efficacy of denosumab, compared with zoledronic acid (ZA), in delaying skeletal-related events (SREs) and enhancing overall survival in patients with advanced solid tumours and bone metastases. A systematic literature search of several electronic databases, including PubMed, Medline, Embase, the Cochrane Library, CKNI and Web of Science with Conference Proceedings, was performed. Only randomised controlled trials assessing denosumab in comparison with ZA, in patients with advanced solid tumours and metastatic-stage disease, were included. The primary outcome was the time to first SRE. The risk of developing subsequent on-study SREs and overall survival were also evaluated. Three randomised controlled trials with a total of 5,544 patients with advanced solid tumours and bone metastases were included in the meta-analysis. There were 2,776 patients treated with denosumab and 2,768 treated with ZA. The pooled analysis showed that denosumab was superior to ZA in delaying time to first on-study SRE (odds ratio [OR]: 0.82; 95% CI: 0.75-0.89, p < 0.0001) and multiple SREs (risk ratio: 0.81; 95% CI: 0.74-0.88, p < 0.0001). However, no significant difference was found in overall survival improvement between denosumab and ZA (OR: 1.02; 95% CI: 0.91-1.15, p = 0.71). This meta-analysis indicates that denosumab is superior to ZA in delaying SREs for patients with bone metastases. No significant difference was observed between denosumab and ZA, regarding overall survival. We support denosumab as a potential novel treatment option for the management of bone metastases in advanced solid tumours.

mTORC1 activation downregulates FGFR3 and PTH/PTHrP receptor in articular chondrocytes to initiate osteoarthritis

OBJECTIVE

Articular chondrocyte activation, involving aberrant proliferation and prehypertrophic differentiation, is essential for osteoarthritis (OA) initiation and progression. Disruption of mechanistic target of rapamycin complex 1 (mTORC1) promotes chondrocyte autophagy and survival, and decreases the severity of experimental OA. However, the role of cartilage mTORC1 activation in OA initiation is unknown. In this study, we elucidated the specific role of mTORC1 activation in OA initiation, and identify the underlying mechanisms.

METHOD

Expression of mTORC1 in articular cartilage of OA patients and OA mice was assessed by immunostaining. Cartilage-specific tuberous sclerosis complex 1 (Tsc1, mTORC1 upstream inhibitor) knockout (TSC1CKO) and inducible Tsc1 KO (TSC1CKO^ER) mice were generated. The functional effects of mTORC1 in OA initiation and development on its downstream targets were examined by immunostaining, western blotting and qPCR.

RESULTS

Articular chondrocyte mTORC1 was activated in early-stage OA and in aged mice. TSC1CKO mice exhibited spontaneous OA, and TSC1CKO^ER mice (from 2 months) exhibited accelerated age-related and DMM-induced OA phenotypes, with aberrant chondrocyte proliferation and hypertrophic differentiation. This was associated with hyperactivation of mTORC1 and dramatic downregulation of FGFR3 and PPR, two receptors critical for preventing chondrocyte proliferation and differentiation. Rapamycin treatment reversed these phenotypes in KO mice. Furthermore, in vitro rescue experiments demonstrated that p73 and ERK1/2 may mediate the negative regulation of FGFR3 and PPR by mTORC1.

CONCLUSION

mTORC1 activation stimulates articular chondrocyte proliferation and differentiation to initiate OA, in part by downregulating FGFR3 and PPR.

Identification of imidazo[1,2-b]pyridazine TYK2 pseudokinase ligands as potent and selective allosteric inhibitors of TYK2 signalling

As a member of the Janus (JAK) family of non-receptor tyrosine kinases, TYK2 mediates the signaling of pro-inflammatory cytokines including IL-12, IL-23 and type 1 interferon (IFN), and therefore represents an attractive potential target for treating the various immuno-inflammatory diseases in which these cytokines have been shown to play a role. Following up on our previous report that ligands to the pseudokinase domain (JH2) of TYK2 suppress cytokine-mediated receptor activation of the catalytic (JH1) domain, the imidazo[1,2-b]pyridazine (IZP) 7 was identified as a promising hit compound. Through iterative modification of each of the substituents of the IZP scaffold, the cellular potency was improved while maintaining selectivity over the JH1 domain. These studies led to the discovery of the JH2-selective TYK2 inhibitor 29, which provided encouraging systemic exposures after oral dosing in mice. Phosphodiesterase 4 (PDE4) was identified as an off-target and potential liability of the IZP ligands, and selectivity for TYK2 JH2 over this enzyme was obtained by elaborating along selectivity vectors determined from analyses of X-ray co-crystal structures of representative ligands of the IZP class bound to both proteins.

Progress in Drug Treatment of Cerebral Edema

Cerebral edema causes intracranial hypertension (ICH) which leads to severe outcome of patients in the clinical setting. Effective anti-edema therapy may significantly decrease the mortality in a variety of neurological conditions. At present drug treatment is a cornerstone in the management of cerebral edema. Osmotherapy has been the mainstay of pharmacologic therapy. Mannitol and hypertonic saline (HS) are the most commonly used osmotic agents. The relative safety and efficacy of HS and mannitol in the treatment of cerebral edema and reduction of enhanced ICP have been demonstrated in the past decades. Apart from its osmotic force, HS exerts anti-edema effects partly through inhibition of Na(+)-K(+)-2Cl(-) Cotransporter-1 (NKCC1) and aquaporin 4 (AQP4) expression in astrocytes. Melatonin may also reduce brain edema and exert neuroprotective effect on several central nervous system diseases through inhibition of inflammatory response. The inhibitors of Na/H exchanger, NKCC and AQP4 may attenuate brain edema formation through inhibition of excessive transportation of ion and water from blood into the cerebral tissue. In this review we survey some of the most recent findings in the drug treatment of brain edema focusing on the use of osmotherapy, melatonin and inhibitors of ion cotransporters and water channels. A better understanding of the molecular mechanism of these agents would help to improve in the clinical management of patients with brain edema.