Identifying prognostic biomarkers for palbociclib add-on therapy in fulvestrant-resistant breast cancer using cell-free DNA sequencing

BACKGROUND

The FUTURE trial (UMIN000029294) demonstrated the safety and efficacy of adding palbociclib after fulvestrant resistance in patients with hormone receptor-positive (HR+)/human epidermal growth factor receptor 2-negative (HER2-) advanced and metastatic breast cancer (ABC/MBC). In this planned sub-study, cancer panel sequencing of cell-free DNA (cfDNA) was utilized to explore prognostic and predictive biomarkers for further palbociclib treatment following fulvestrant resistance.

MATERIALS AND METHODS

Herein, 149 cfDNA samples from 65 patients with fulvestrant-resistant disease were analysed at the time of palbociclib addition after fulvestrant resistance (baseline), on day 15 of cycle 1, and at the end of treatment using the assay for identifying diverse mutations in 34 cancer-related genes.

RESULTS

During the course of treatment, mutations in ESR1, PIK3CA, FOXA1, RUNX1, TBX3, and TP53 were the most common genomic alterations observed. Analysis of genomic mutations revealed that before fulvestrant introduction, baseline PIK3CA mutations were marginally lower in metastatic aromatase inhibitor (AI)-treated patients compared to adjuvant AI-treated patients (P = 0.063). Baseline PIK3CA mutations were associated with poorer progression-free survival [hazard ratio: 1.62, P = 0.04]. Comparative analysis between baseline and early-changing gene mutations identified poor prognostic factors including early-changing MAP3K1 mutations (hazard ratio: 4.66, P = 0.04), baseline AR mutations (hazard ratio: 3.53, P = 0.04), and baseline PIK3CA mutations (hazard ratio: 3.41, P = 0.02). Notably, the relationship between ESR1 mutations and mutations in PIK3CA, MAP3K1, and TP53 weakened as treatment progressed. Instead, PIK3CA mutations became correlated with TP53 and FOXA1 mutations.

CONCLUSIONS

Cancer panel testing for cfDNA identified prognostic and predictive biomarkers for palbociclib add-on therapy after acquiring fulvestrant resistance in patients with HR+/HER2- ABC/MBC.

Notch signaling genes and CD8+ T-cell dynamics: Their contribution to immune-checkpoint inhibitor therapy in oral squamous cell carcinoma: A retrospective study

BACKGROUND

Aberrant Notch signaling pathway has been related with the tumorigenesis in head and neck region, involving oral cavity. Here, we report the correlation between mutations in the Notch signaling pathway and CD8+ T-cell infiltration via PD-L1, which lead to enhanced antitumor immunity and may target for immune-checkpoint inhibitors (ICIs) therapy.

METHODS

This retrospective study analyzed the results of immunohistochemical staining for PD-L1 and CD8+ T-cell infiltration in 10 patients and whole-exome sequencing (WES) was conducted on five of these patients to identify frequently mutated genes.

RESULTS

Four of 10 patients were positive for PD-L1 and CD8+ T. By analyzing WES in three of these four patients, we notably identified the mutations of NOTCH1, FBXW7, and noncoding RNA intronic mutation in NOTCH2NLR in two of these three patients. This study may enable better selection of ICI therapy with CD8+ T-cell infiltration via PD-L1 expression for oral squamous cell carcinoma patients with mutations in Notch signaling pathway.

Binuclear Complexes Supported by a Tetrapyridyl Ligand with a Bending Anthraquinodimethane Linker

A tetrapyridyl ligand with a bending anthraquinodimethane linker has been synthesized, and its complexation with coinage metals has been examined. The treatment of the ligand with Ag(I) and Au(I) cations afforded binuclear complexes, wherein the two metal centers were in close proximity to the inside space of the ligand. X-ray analyses corroborated with theoretical calculations indicated that the ligand has reasonable flexibility toward a bending deformation of the linker moiety to provide a ligand pocket suitable for the proximal binuclear complexes, even though such deformations accompany a non-negligible amount of energetic cost. On the other hand, treatment with 2 equiv of Cu(I) salt afforded a binuclear complex, in which both copper atoms were coordinated at the periphery of the ligand.

One-pot Syntheses of Benzo- and Benzofuran-fused Iridaoxabenzenes via CH Bond Activations of Alkyl-bridged Diphenol Derivatives

One-pot syntheses of new π-extended metallaaromatic compounds have been developed by utilizing Ir-mediated CH bond activation of ethylene- or ethylidene-bridged diphenol derivatives. Depending on the bridging alkyl groups, two types of iridaoxabenzenes, both of which are doubly fused with benzo and benzofuran units, have been obtained. Studies on their structures and electronic characters indicate that both complexes have an aromatic character on the iridaoxacycles, and their π-conjugated systems are fully delocalized over the whole molecular skeletons. These novel metallaaromatic complexes exhibited some reactivities which are distinct from those reported for the non-fused metallaaromatic compounds.

Perineural treatment with anti-TNF-α antibody ameliorates persistent allodynia and edema in novel mouse models with complex regional pain syndrome

Complex regional pain syndrome (CRPS) is an intractable chronic pain syndrome with various signs and symptoms including allodynia/hyperalgesia, edema, swelling, and skin abnormalities. However, a definitive therapeutic treatment for CRPS has not been established. In CRPS patients, inflammatory cytokines such as TNF-α and IL-1β have been shown to increase in affected areas, suggesting that these molecules may be potential therapeutic targets for CRPS. Here, we first created a novel CRPS mouse model (CRPS-II-like) via sciatic nerve injury and cast immobilization, which was characterized by mechanical allodynia, local edema, and skin abnormalities, to evaluate the pathophysiology and pharmacotherapy of CRPS. When an anti-TNF-α antibody was consecutively administered near the injured sciatic nerve of CRPS model mice, persistent allodynia and CRPS-related signs in the ipsilateral hindpaw were markedly attenuated to control levels. Perineural administration of anti-TNF-α antibody also suppressed the upregulation of inflammatory cytokines as well as the activation of macrophages and Schwann cells in the injured sciatic nerve. These findings indicate that persistent allodynia and CRPS-related signs in CRPS models are primarily associated with TNF-α-mediated immune responses in injured peripheral nerves, suggesting that perineural treatment with anti-TNF-α antibody might be therapeutically useful.

A rare case report of diverticulum of the buccal mucosa

We report a case of diverticulum of the buccal mucosa. A 56-year-old man had a small pouch-shaped lesion behind the parotid papilla that caused pain and food impaction. After resection, the lesion was histopathologically diagnosed as diverticulum without buccal muscle tear. There has been no recurrence during 1 year postoperatively.

Improvement of solubility of phospholipase D from Streptomyces antibioticus in recombinant Escherichia coli and its application for the enzymatic synthesis of a non-natural plasmalogen

Plasmalogens are a subclass of glycerophospholipid that have a vinyl-ether bond at the sn-1 position and are thought to have several physiological functions. The creation of non-natural plasmalogens with functional groups is desired for the establishment of the prevention of diseases caused by the depletion of plasmalogens. Phospholipase D (PLD) has both hydrolysis and transphosphatidylation activities. In particular, PLD from Streptomyces antibioticus has been investigated extensively due to its high transphosphatidylation activity. However, it has been difficult to stably express recombinant PLD in Escherichia coli and to express it as a soluble protein. In this study, we used the E. coli strain, SoluBL21™, and achieved stable PLD expression from the T7 promoter and increased soluble fraction in a cell. We also improved the purification method of PLD using His-tag at the C terminus. We obtained PLD with approximately 730 mU mg-1 protein of specific activity, and the yield was approximately 420 mU l-1 culture corresponding to 76 mU per gram wet cells. Finally, we synthesized a non-natural plasmalogen with 1,4-cyclohexanediol bound to the phosphate group at the sn-3 position by transphosphatidylation of the purified PLD. This method will contribute to the expansion of the chemical structure library of non-natural plasmalogens.

GC-MS analysis of exhaled gas for fine detection of inflammatory diseases

Exhaled gas analysis is a non-invasive test ideal for continuous monitoring of biological metabolic information. We analyzed the exhaled gas of patients with inflammatory diseases for trace gas components that could serve as biomarkers that enable early detection of inflammatory diseases and assessment of treatment efficacy. Furthermore, we examined the clinical potential of this method. We enrolled 34 patients with inflammatory disease and 69 healthy participants. Volatile components from exhaled gas were collected and analyzed by a gas chromatography-mass spectrometry system, and the data were examined for gender, age, inflammatory markers, and changes in markers before and after treatment. The data were tested for statistical significance through discriminant analysis by Volcano plot, Analysis of variance test, principal component analysis, and cluster analysis comparing healthy and patient groups. There were no significant differences in the trace components of exhaled gas by gender or age. However, we found differences in some components of the exhaled gas between healthy and untreated patients. In addition, after treatment, gas patterns including the patient-specific components changed to a state closer to the inflammation-free status. We identified trace components in the exhaled gas of patients with inflammatory diseases and found that some of these regressed after treatment.

Investigation of in-line filter replacement intervals for infusion

BACKGROUND

In-line filters in peripheral and central venous catheters are used to remove bacterial cells mechanically. A recent study indicated an extension of the use of infusion sets to 7 days. There is no evidence regarding replacement intervals for in-line filters.

AIM

To test in-line filters that were used continuously for 7 days in order to investigate their ability to remove bacteria and assess the flow rate.

METHODS

Three different in-line filters were attached to an ELNEOPA-NF No. 2 premixed infusion bag of intravenous hyperalimentation, into which Staphylococcus epidermidis ATCC12228 or Escherichia coli ATCC25922 was inoculated. These experiments were compared with a control infusion. The infusion was dropped at a flow rate of 40 mL/h and replaced at 24-h intervals for 7 days. Samples were collected 24 h after drop initiation.

FINDINGS

S. epidermidis was not detected in droplets between Days 1 and 6, but In-line filters 1 and 2 showed droplets containing 6-10 colony-forming units/mL on Day 7. E. coli was not detected in any of the filters after 7 days of continuous use. Flow rates <40 mL/h were observed on Day 7 for In-line filter 3 in studies of S. epidermidis, and on Days 4 and 3 for In-line filters 2 and 3, respectively, in studies of E. coli.

CONCLUSION

This study revealed differences in bacterial removal and flow rates under high inoculation between the three in-line filters tested. It is suggested that in-line filters can be used continuously for a maximum of 6 days, and reductions in flow rate after 48 h of continuous use should be noted carefully.

Inhibition of transient receptor potential cation channel 6 promotes capillary arterialization during post-ischaemic blood flow recovery

BACKGROUND AND PURPOSE

Capillary arterialization, characterized by the coverage of pre-existing or nascent capillary vessels with vascular smooth muscle cells (VSMCs), is critical for the development of collateral arterioles to improve post-ischaemic blood flow. We previously demonstrated that the inhibition of transient receptor potential 6 subfamily C, member 6 (TRPC6) channels facilitate contractile differentiation of VSMCs under ischaemic stress. We here investigated whether TRPC6 inhibition promotes post-ischaemic blood flow recovery through capillary arterialization in vivo.

EXPERIMENTAL APPROACH

Mice were subjected to hindlimb ischaemia by ligating left femoral artery. The recovery rate of peripheral blood flow was calculated by the ratio of ischaemic left leg to non-ischaemic right one. The number and diameter of blood vessels were analysed by immunohistochemistry. Expression and phosphorylation levels of TRPC6 proteins were determined by western blotting and immunohistochemistry.

KEY RESULTS

Although the post-ischaemic blood flow recovery is reportedly dependent on endothelium-dependent relaxing factors, systemic TRPC6 deletion significantly promoted blood flow recovery under the condition that nitric oxide or prostacyclin production were inhibited, accompanying capillary arterialization. Cilostazol, a clinically approved drug for peripheral arterial disease, facilitates blood flow recovery by inactivating TRPC6 via phosphorylation at Thr69 in VSMCs. Furthermore, inhibition of TRPC6 channel activity by pyrazole-2 (Pyr2; BTP2; YM-58483) promoted post-ischaemic blood flow recovery in Apolipoprotein E-knockout mice.

CONCLUSION AND IMPLICATIONS

Suppression of TRPC6 channel activity in VSMCs could be a new strategy for the improvement of post-ischaemic peripheral blood circulation.

Acceptance of Murine Islet Allografts Without Immunosuppression in Inguinal Subcutaneous White Adipose Tissue Pretreated With bFGF

Prevention of immune rejection without immunosuppression is the ultimate goal of transplant immunobiology. One way to achieve this in cellular transplantation, such as with islet transplantation, is to create a favorable local environment at the transplant site. In the current study, we found that C57BL/6 mice with streptozotocin-induced diabetes remained normoglycemic for >1 year after transplantation of BALB/c islets without immunosuppression when the inguinal subcutaneous white adipose tissue (ISWAT) was the site of transplantation and when the site was pretreated with basic fibroblast growth factor. Mechanistically, mesenchymal stem cells (MSCs) expanded in the ISWAT after the treatment was found to produce transforming growth factor-β (TGF-β), and prevention of islet allograft rejection could be achieved by cotransplantation with syngeneic MSCs isolated from the ISWAT after the treatment, which was abolished by anti-TGF-β antibody treatment. Importantly, TGF-β-producing cells remained present at the site of cotransplantation up to the end of observation period at 240 days after transplantation. These findings indicate that prevention of islet allograft rejection without immunosuppression is feasible with the use of syngeneic TGF-β-producing MSCs expanded in the ISWAT after the treatment with bFGF, providing a novel strategy for prevention of islet allograft rejection without immunosuppression.

Lymphangiogenesis and angiogenesis rescue murine ischemic hindlimb via transient receptor potential vanilloid 4

In this study, we assessed the regulation of transient receptor potential vanilloid 4 (TRPV4) promoting lymphangio/angiogenesis to improve the ischemic hindlimb animal model, and revealed that (1) a TRPV4 agonist improved the blood flow of ischemic hindlimbs by inducing both angiogenesis and lymphangiogenesis; (2) excessive TRPV4 expression was detected on lymphatic endothelial cells (LECs) in the ischemic hindlimb; and (3) hypoxic conditions promoted Ca²⁺ influx into LECs via TRPV4. It is considered that the upregulation of both lymphatic and blood vessels by activating TRPV4 would be a promising therapeutic strategy for peripheral artery disease.

Na+/Ca2+ exchanger mediates cold Ca2+ signaling conserved for temperature-compensated circadian rhythms

Circadian rhythms are based on biochemical oscillations generated by clock genes/proteins, which independently evolved in animals, fungi, plants, and cyanobacteria. Temperature compensation of the oscillation speed is a common feature of the circadian clocks, but the evolutionary-conserved mechanism has been unclear. Here, we show that Na⁺/Ca²⁺ exchanger (NCX) mediates cold-responsive Ca²⁺ signaling important for the temperature-compensated oscillation in mammalian cells. In response to temperature decrease, NCX elevates intracellular Ca²⁺, which activates Ca²⁺/calmodulin-dependent protein kinase II and accelerates transcriptional oscillations of clock genes. The cold-responsive Ca²⁺ signaling is conserved among mice, Drosophila, and Arabidopsis The mammalian cellular rhythms and Drosophila behavioral rhythms were severely attenuated by NCX inhibition, indicating essential roles of NCX in both temperature compensation and autonomous oscillation. NCX also contributes to the temperature-compensated transcriptional rhythms in cyanobacterial clock. Our results suggest that NCX-mediated Ca²⁺ signaling is a common mechanism underlying temperature-compensated circadian rhythms both in eukaryotes and prokaryotes.

Genetic knockout and pharmacologic inhibition of NCX1 attenuate hypoxia-induced pulmonary arterial hypertension

The Na⁺/Ca²⁺ exchanger type-1 (NCX1) is a bidirectional transporter that is controlled by membrane potential and transmembrane gradients of Na⁺ and Ca²⁺. Vascular smooth muscle NCX1 plays an important role in intracellular Ca²⁺ homeostasis and Ca²⁺ signaling. We found that NCX1 was upregulated in the pulmonary arteries of mice exposed to chronic hypoxia (10% O₂ for 4 weeks). Hence, we investigated the pathophysiological role of NCX1 in hypoxia-induced pulmonary arterial hypertension (PAH), using NCX1-heterozygous (NCX1^+/-) mice, in which NCX1 expression is reduced by half, and SEA0400, a specific NCX1 inhibitor. NCX1^+/- mice exhibited attenuation of hypoxia-induced PAH and right ventricular (RV) hypertrophy compared with wild-type mice. Furthermore, continuous administration of SEA0400 (0.5 mg/kg/day for 4 weeks) to wild-type mice by osmotic pumps significantly suppressed hypoxia-induced PAH and pulmonary vessel muscularization, with a slight reduction in RV hypertrophy. These findings indicate that the upregulation of NCX1 contributes to the development of hypoxia-induced PAH, suggesting that NCX1 inhibition might be a novel approach for the treatment of PAH.

Sodium-calcium exchanger 1 is the key molecule for urinary potassium excretion against acute hyperkalemia

The sodium (Na⁺)-chloride cotransporter (NCC) expressed in the distal convoluted tubule (DCT) is a key molecule regulating urinary Na⁺ and potassium (K⁺) excretion. We previously reported that high-K⁺ load rapidly dephosphorylated NCC and promoted urinary K⁺ excretion in mouse kidneys. This effect was inhibited by calcineurin (CaN) and calmodulin inhibitors. However, the detailed mechanism through which high-K⁺ signal results in CaN activation remains unknown. We used Flp-In NCC HEK293 cells and mice to evaluate NCC phosphorylation. We analyzed intracellular Ca²⁺ concentration ([Ca²⁺]_in) using live cell Ca²⁺ imaging in HEK293 cells. We confirmed that high-K⁺-induced NCC dephosphorylation was not observed without CaN using Flp-In NCC HEK29 cells. Extracellular Ca²⁺ reduction with a Ca²⁺ chelator inhibited high-K⁺-induced increase in [Ca²⁺]_in and NCC dephosphorylation. We focused on Na⁺/Ca²⁺ exchanger (NCX) 1, a bidirectional regulator of cytosolic Ca²⁺ expressed in DCT. We identified that NCX1 suppression with a specific inhibitor (SEA0400) or siRNA knockdown inhibited K⁺-induced increase in [Ca²⁺]_in and NCC dephosphorylation. In a mouse study, SEA0400 treatment inhibited K⁺-induced NCC dephosphorylation. SEA0400 reduced urinary K⁺ excretion and induced hyperkalemia. Here, we identified NCX1 as a key molecule in urinary K⁺ excretion promoted by CaN activation and NCC dephosphorylation in response to K⁺ load.

Factors secreted from dental pulp stem cells show multifaceted benefits for treating experimental temporomandibular joint osteoarthritis

OBJECTIVE

Temporomandibular joint osteoarthritis (TMJOA) is a degenerative disease characterized by progressive cartilage degeneration, abnormal bone remodeling, and chronic pain. In this study, we aimed to investigate effective therapies to reverse or suppress TMJOA progression.

DESIGN

To this end, we performed intravenous administration of serum free conditioned media from human exfoliated deciduous teeth stem cells (SHED-CM) into a mechanical-stress induced murine TMJOA model.

RESULTS

SHED-CM administration markedly suppressed temporal muscle inflammation, and improved bone integrity and surface smoothness of the destroyed condylar cartilage. Moreover, SHED-CM treatment decreased the number of IL-1β, iNOS, and MMP-13 expressing chondrocytes, whereas it specifically increased PCNA-positive cells in the multipotent polymorphic cell layer. Notably, the numbers of TdT-mediated dUTP nick end labeling (TUNEL)-positive apoptotic chondrocytes in the SHED-CM treated condyles were significantly lower than in those treated with DMEM, whereas the proteoglycan positive area was restored to a level similar to that of the sham treated group, demonstrating that SHED-CM treatment regenerated the mechanical-stress injured condylar cartilage and subchondral bone. Secretome analysis revealed that SHED-CM contained multiple therapeutic factors that act in osteochondral regeneration.

CONCLUSIONS

Our data demonstrated that SHED-CM treatment promoted the regeneration and repair of mechanical-stress induced mouse TMJOA. Our observations suggest that SHED-CM has potential to be a potent tissue-regenerating therapeutic agent for patients with severe TMJOA.

Endergonic addition of N-methylamines to aromatic ketones driven by photochemical offset of the entropic cost

Intermolecular addition reactions are generally accompanied by an entropic penalty due to the decrease of molecular numbers during the reaction, which sometimes makes the reaction endergonic. Here we demonstrate that such an endergonic reaction can be promoted with light-energy as a driving force; N-methylamines were added to aromatic ketones to produce aminoalcohols under UV-light irradiation. The reaction represents an obvious example showing that the photochemical approach is effective to offset such an entropic cost, and thereby to drive thermodynamically uphill addition reactions. Moreover the present reactions are highly expedient from the synthetic view point, being transition-metal-catalyst-free, scalable, highly atom economical, and regioselective. The product amines can be converted in one step to functional multi-arylated enamines, which are potentially valuable compounds in electronic materials.

Abstract P4-08-19: Progression-free survival or time to progression in comparative clinical trials of metastatic breast cancer as a potential surrogate for overall survival: A systematic review of 49 trials focusing on breast cancer subtype

Background: Overall survival (OS) is the established endpoint to evaluate the effects of drug treatment in comparative clinical trials of metastatic breast cancer. But assessing OS requires long follow-up periods and large sample size, which raise costs and create long delays in the drug approval process. Progression-free survival (PFS) or time to progression (TTP) is considered as a surrogate for OS and is often used as an alternative to OS. In some cancers the two endpoints are highly correlated, but in others they are not. Furthermore, the effect of breast cancer (BC) subtypes on the surrogacy of PFS/TTP for OS has not been completely defined.

Method: A systematic literature review of randomized control trials was conducted to identify studies that reported both the hazard ratio (HR) of PFS/TTP and OS for BC subtypes {i.e. estrogen receptor (ER) positive, HER2 positive, and triple negative (TN)}. The correlation between the HR of PFS/TTP and OS was evaluated using weighted Spearman's rank correlation.

Results: A total of 49 trials (34 phase III trials and 15 phase II trials) were selected for analysis. Among these trials, there were 8 comparison trials between one chemotherapy and another chemotherapy regimen, 18 comparison trials between chemotherapy and chemotherapy plus molecularly-targeted therapy, 9 comparison trials between one endocrine therapy and another endocrine therapy, and 5 comparison trials between endocrine therapy and endocrine therapy plus molecularly-targeted therapy. There were 17 trials reporting the HR of PFS/TTP and OS for ER positive, 16 trials for HER2 positive, and 9 trials for TN BC. Weighted Spearman's rank correlation revealed that coefficient between the HR of PFS/TTP and OS was 0.721(p&lt;.0001) for all trials, 0.873(p&lt; .0001) for ER positive, 0.642(p=0.0055) for HER2 positive, and 0.615(p=0.078)for TN BC.

Conclusion: There was a strong correlation between the HR of PFS/TTP and OS for ER positive BC, and a weak correlation between the HR of PFS/TTP and OS for HER2 positive and TN BC. The validity of using PFS/TTP as an OS surrogate marker was shown for metastatic BC, especially for ER positive BC.

Citation Format: Tsukioki T, Taira N, Sakamaki K, Suzuki Y, Kajiwara Y, Hatono M, Takahashi Y, Kawata K, Kochi M, Iwamoto T, Ikeda H, Shien T, Doihara H. Progression-free survival or time to progression in comparative clinical trials of metastatic breast cancer as a potential surrogate for overall survival: A systematic review of 49 trials focusing on breast cancer subtype [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 P4-08-19.

Abstract P2-05-06: Effects of a soy isoflavone in breast cancer treatment

Background : Isoflavones are phytoestrogens that may be effective in preventing osteoporosis, reducing cardiovascular events, and improving menopausal symptoms such as hot flash due to their estrogen-like actions. Isoflavones are currently used as a supplement for improving symptoms of menopause. Epidemiological studies have shown that ingestion of soy products may also reduce the risk of breast cancer, and antitumor effects on hormone receptor (HR)-positive breast cancer cells have been shown in vitro for equol, an isoflavone metabolite. Equol binds to estrogen receptors (ERα, β) and is thought to antagonize ERα-estradiol binding in the presence of estradiol. Since equol shows an antiestrogenic effect, similar to that of the hormonal agent tamoxifen, it is thought that equol acts as a selective estrogen receptor modulator (SERM), but the mechanism is still unclear. In this study, we evaluated the antitumor effects of equol alone and in combination with existing therapeutic agents in HR-positive breast cancer cells, and examined the mechanism of these effects.

Methods : The antitumor effects of equol alone and in combination with hormone drugs (4-hydroxytamoxifen (Tam), fulvestrant (Ful)) and chemotherapeutic agents (paclitaxel (Ptx), doxorubicin (Dox)) were examined using a MTS assay. Combination indexes (CIs) were determined in HR-positive MCF-7, T-47D, and ZR-75-1 cell lines. The mechanisms of the drug effects were evaluated by Western blot for assessment of changes in chemoresistance factors at the protein level.

Results : In MCF-7, T-47D and ZR-75-1 cells, there was a concentration-dependent antitumor effect of equol and of the other hormonal agents. CIs showed an antagonistic effect of equol with Tam and a synergistic effect with Ful in all cell lines. Equol also had an antagonistic effect with the two chemotherapeutic agents, with the strongest antagonism occurring at a low dose of equol. Western blot showed that ER, PgR, Cyclin D1 and Bcl-2 were upregulated via ER at a low concentration of equol, similarly to the effect of 17-β-estradiol (E2), and ER, PgR, Cyclin D1 and Bcl-2 were downregulated at a high concentration, similarly to the effect of Tam. In addition, ER, PgR and cyclin D1 were downregulated with the combination of equol and Tam, while the expression of Bcl-2, a chemoresistance factor, increased.

Conclusion : These results suggest that equol has a concentration-dependent antitumor effect in HR-positive breast cancer cell lines and may antagonize the effect of existing therapeutic agents (hormone drugs and chemotherapeutic agents). In particular, it was considered that in combination of equol and Tam, the apoptosis inducing action of each drug was attenuated and antagonistic effect was shown.

Citation Format: Hatono M, Ikeda H, Taira N, Suzuki Y, Kajiwara Y, Kawata K, Takahashi Y, Tsukioki T, Kochi M, Iwamoto T, Shien T, Doihara H. Effects of a soy isoflavone in breast cancer treatment [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 P2-05-06.

Abstract P4-13-09: Sequential second line endocrine therapy is still an effective strategy for postmenopausal ER+ and HER2- advanced breast cancer with low sensitivity to initial endocrine therapy

Background:It is unclear how to define responsiveness to endocrine therapy (ET) during the clinical course of advanced breast cancer (ABC), especially in evaluation of the effect of sequential ET. Objective:The goal of the study was to evaluate the efficacy of second line treatment of physician's choice (2nd-line TPC) for estrogen receptor-positive (ER+) and HER2-negative postmenopausal ABC with very low or low sensitivity to initial ET. Methods:A multicenter prospective observational cohort study was performed for 2nd-line TPCs. ABC with low sensitivity to initial ET was defined as recurrence within 5 years (yrs) during adjuvant ET or progression within 9 months (mo.) of initial ET. Similarly, ABC with very low sensitivity to initial ET was defined as recurrence within 2 yrs during adjuvant ET or progression within 3 mo. of initial ET. The expected clinical benefit rate (CBR: defined as patients who achieved CR, PR or SD for 24 weeks) was 50%. The null hypothesis of a CBR of 30% was tested with a one-sided α of 5%. 90% confidence intervals (CIs) were calculated for hypothesis tests. Results: A total of 56 patients (pts) were enrolled, but 7 were ineligible and one discontinued before starting the protocol treatment. The median age was 66 yrs (range: 41-88) and the median BMI was 23.4 kg/m2 (16.4-31.9). All pts were ER+ and 80% were PgR+. Most of pts had a baseline PS of 0 or 1, 90% had invasive ductal carcinoma, and 10% had invasive lobular carcinoma. Postoperative recurrence was detected in 84% and these pts had a median duration of adjuvant ET of 30.5 mo. (5.3-58.9). De novo stage IV ABC was present in 16%, with a median duration of first-line ET of 5 mo. (2.3-10.8). Adjuvant chemotherapy including anthracycline- and/or a taxane-containing regimen was administered in 58% (29/49). As adjuvant ET before initial recurrence, 34 pts received non-steroidal aromatase inhibitors (AIs) (88.0%), 1 received a steroidal AI (2.3%), and 3 received a selective estrogen receptor modulator (SERM). As first line ET in de novo stage IV, 7 pts (14%) were treated with AIs or a SERM (1 case). 2nd-line TPCs were also used, with 40 pts receiving fulvestrant (82%), 5 receiving SERMs (10%), 3 receiving a mTOR inhibitor plus a steroidal AI (6%), and one patient receiving an AI alone. The overall CBR was 44.9% (90% CI: 34.6-57.6, p=0.009), and CBR was similar across following subgroups (PgR+: n=39, 51.3%, 90% CI: 39.6-65.2, p=0.0016; very low sensitivity group: n=17, 58.8%, 90% CI: 42.0-78.8, p=0.003; non-visceral metastases: n=25, 40%, 90% CI; 34.1-65.9, p=0.0175). However, there were not statistically significant CBR in PgR- (n=10, 20.0%, 90% CI; 8.73-50.7, p=0.617), fulvestrant subgroup (n=40, 40.0 %, 90% CI; 29.2-54.2, p=0.063), low sensitive group (n=32, 37.5%, 90% CI; 26.0-53.6, p=0.1326), and visceral metastases (n=24, 48%, 90%CI; 28.2-60.3 p=0.072). The median PFS was 7.1 mo. (95% CI: 5.6-10.6). Conclusion:This study shows that 2nd line ETs was effective and might be a valid option in the sequence of treatments for postmenopausal women with ABC with low sensitivity to initial ET. It was suggested that PgR and visceral metastasis were significant predictive factors for CBR.

Citation Format: Araki K, Fujisawa T, Sakamaki K, Kikawa Y, Iwamoto T, Sangai T, Shien T, Takao S, Nishimura R, Takahashi M, Aihara T, Mukai H, Taira N. Sequential second line endocrine therapy is still an effective strategy for postmenopausal ER+ and HER2- advanced breast cancer with low sensitivity to initial endocrine 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 P4-13-09.

Abstract P2-08-31: Predictive and prognostic value of stromal tumor-infiltrating lymphocytes before and after neoadjuvant therapy in triple negative and HER2-positive breast cancer

Background: Lymphocyte predominant breast cancer subgroup, defined as ≥ 50% stromal tumor-infiltrating lymphocytes (sTILs), is associated with high pathological complete response (pCR) rate after neoadjuvant therapy (NAT) and favorable outcome. In a cohort of triple negative (TNBC) and HER2+ breast cancer (BC) patients treated with NAT, we aimed to assess the predictive and prognostic value of pre- and post-NAT sTILs and the information provided by the change in sTILs during NAT.

Materials and methods: Two-hundred and nine consecutive patients (n=80 TNBC; and n=129 HER2+) who received NAT between 2001 and 2009 in our institution were evaluated. Pre-NAT sTILs were assessed on biopsy sample (baseline) and post-NAT sTILs on surgical specimens just for non-pCR patients. sTILs level was categorized as low 0-9%, intermediate 10-49%, and high ≥50%. The change in sTILs during NAT was calculated as the absolute difference between pre- and post-NAT sTILs. We evaluated the association of pre-NAT sTILs and pCR, and the association between pre- and post-NAT sTILs, and their change with relapse-free survival (RFS).

Results: Overall pCR rate was 37.8% (31.3% for TNBC, 41.2% for ER+/HER2+BC, 42.3% for ER-/HER2+BC). In each subtype, pre-NAT low sTILs group was significantly associated with lower pCR rate. During the median follow-up period of 98 months, 44 recurrences (21.1%) were observed. For TNBC, low pre-NAT sTILs group was associated with higher recurrence risk compared with int/high sTILs (HR=4.675 [2.013-10.859], p&lt;0.001). For only non-pCR patients, both pre- and post-NAT sTILs were significantly associated with RFS. The risk of recurrence was higher in the group with low pre-NAT sTILs (HR=5.333 [1.731-16.427], p=0.004), and the group of low post-NAT sTILs (HR=4.271 [1.498-12.173], p=0.007). Patients with the change of sTILs increase during NAT were not associated with RFS, compared with decrease or equal group (log-rank p=0.163). In multivariate analysis including both pre- and post-NAT sTILs, only pre-NAT sTILs retained significance (HR=3.844 [1.190-12.421], p=0.024). Low post-NAT sTILs group showed only a borderline significant association with shorter RFS (HR=2.836 [0.951-8.457], p=0.061), but it suggests that both pre- and post-NAT sTILs might provide independent prognostic information. In ER+/HER2+BC, low pre-NAT sTILs were associated with short RFS (p=0.036), but this association was not significant when only non-pCR patients were considered. In ER−/HER2+BC, sTILs were not significantly associated with RFS.

Conclusion: In TN and HER2+ BCs, tumors with low pre-NAT sTILs have a low likelihood to achieve a pCR (predictive marker). In TNBC, low pre-NAT sTILs were associated with higher recurrence risk. In non-pCR TNBC patients, both low pre- and post-NAT sTILs were associated with shorter RFS. These results suggest that sTILs information should be taken into account when additional post-surgery treatments are considered in non-pCR patients.

Citation Format: Ochi T, Giampaolo B, Murai M, Nozaki F, Kobayashi D, Iwamoto T, Niikura N, Suzuki K, Yamauchi H, Hayashi N. Predictive and prognostic value of stromal tumor-infiltrating lymphocytes before and after neoadjuvant therapy in triple negative and HER2-positive breast cancer [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 P2-08-31.

GENOMICS AND LOCAL ADAPTATION OF MYCOBACTERIUM AVIUM

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Iron-catalysed enantioselective Suzuki–Miyaura coupling of racemic alkyl bromides

The first iron-catalyzed enantioselective Suzuki–Miyaura coupling reaction has been established by using electron-deficient P-chiral bisphosphine ligand (R,R)-QuinoxP*.

[Dysfunction of Na+/Ca2+ exchangers is associated with cognitive decline in Alzheimer's disease]

Na⁺/Ca²⁺ exchanger (NCX) is mainly expressed in the plasma membrane and mediates electrogenical exchange of one Ca²⁺ for three Na⁺, depending on the electrochemical gradients across the plasma membrane. NCX has three different isoforms (NCX1, NCX2, NCX3) encoded by distinct genes in mammals. Here, we report that NCX2 and NCX3 protein levels are relatively reduced in hippocampal CA1 of Alzheimer's disease model mice. Likewise, NCX2^+/- or NCX3^+/- mice exhibited impaired hippocampal LTP and memory-related behaviors. In immunoblot analyses, calcium/calmodulin-dependent protein kinase II (CaMKII) autophosphorylation significantly decreased in hippocampal CA1 of NCX2^+/- mice compared to wild-type mice. By contrast, NCX2^+/- mice was correlated with elevated calcineurin (CaN) activity and rescued by treatment with the calcineurin inhibitor FK506. Taken together, the imbalance of CaMKII and CaN activities with concomitant LTP impairment likely accounts for the learning disability observed in NCX2^+/- mice.

Aberrant Amygdala-Dependent Cued Fear Memory in Na+/Ca2+ Exchanger 1 Heterozygous Mice

Na⁺/Ca²⁺ exchangers (NCXs) are mainly expressed in the plasma membrane and exchange one Ca²⁺ for three Na⁺, depending on the electrochemical gradients across the plasma membrane. NCXs have three isoforms, NCX1-3, encoded by distinct genes in mammals. Here, we report that heterozygous mice lacking NCX1 (NCX1^+/-) exhibit impaired amygdala-dependent cued fear memory. NCX1^+/- mice showed significant impairment in fear-related behaviors measured with the elevated-plus maze, light-dark, open-field, and marble-burying tasks. In addition, NCX1^+/- mice showed abnormality in cued fear memory but not in contextual fear memory in a fear-conditioning task. In immunohistochemical analyses, NCX1^+/- mice had significantly increased number of c-Fos-positive cells in the lateral amygdala (LA) but not in the central amygdala following fear-related tone stimuli. c-Fos expression peaked at 1 h. In concordance with the aberrant fear-related behaviors in NCX1^+/- mice, enhanced long-term potentiation was also observed in the LA of these mice. Furthermore, enhancement of CaMKII or CaMKIV activity in the LA was observed in NCX1^+/- mice by immunoblot analyses. In contrast, CaMKII^+/- but not CaMKIV^-/- mice insufficiently exhibited tone-induced cued fear memory and there was no increase in the number of c-Fos-positive cells in the LA. Altogether, the increased CaMKII activity and consequent c-Fos expression likely account for the dysregulation of amygdala-dependent cued fear memory in NCX1^+/- mice.

Revisiting the definition of estrogen receptor positivity in HER2-negative primary breast cancer

Background

Although 1% has been used as cut-off for estrogen receptor (ER) positivity, several studies have reported that tumors with ER < 1% have characteristics similar to those with 1% ≤ ER < 10%. We hypothesized that in patients with human epidermal growth factor 2 (HER2)-negative breast cancer, a cut-off of 10% is more useful than one of 1% in discriminating for both a better pathological complete response (pCR) rate to neoadjuvant chemotherapy and a better long-term outcome with adjuvant hormonal therapy. Our objectives were to identify a percentage of ER expression below which pCR was likely and to determine whether this cut-off value can identify patients who would benefit from adjuvant hormonal therapy.

Patients and methods

Patients with stage II or III HER2-negative primary breast cancer who received neoadjuvant chemotherapy followed by definitive surgery between June 1982 and June 2013 were included. Logistic regression models were used to assess the association between each variable and pCR. Cox models were used to analyze time to recurrence and overall survival. The recursive partitioning and regression trees method was used to calculate the cut-off value of ER expression.

Results

A total of 3055 patients were analyzed. Low percentage of ER was significantly associated with high pCR rate (OR = 0.99, 95% CI = 0.986-0.994, P < 0.001). The recommended cut-off of ER expression below which pCR was likely was 9.5%. Among patients with ER ≥ 10% tumors, but not those with 1%≤ER < 10% tumors, adjuvant hormonal therapy was significantly associated with long time to recurrence (HR = 0.24, 95% CI = 0.16-0.36, P < 0.001) and overall survival (HR = 0.32, 95% CI = 0.2-0.5, P < 0.001).

Conclusion

Stage II or III HER2-negative primary breast cancer with ER < 10% behaves clinically like triple-negative breast cancer in terms of pCR and survival outcomes and patients with such tumors may have a limited benefit from adjuvant hormonal therapy. It may be more clinically relevant to define triple-negative breast cancer as HER2-negative breast cancer with <10%, rather than <1%, of ER and/or progesterone receptor expression.

Abstract P4-14-02: CSF1/CSF1R axis reprograms epithelial-to-mesenchymal phenotypes in inflammatory breast cancer

Inflammatory breast cancer (IBC) accounts for 2% of breast cancers but 10% of breast cancer-related deaths in the US. Clinical hallmarks of IBC are tumor cell emboli in lymphatic vessels and overexpression of E-cadherin, which promotes cell clustering. Given these hallmarks, IBC is thought to spread via collective invasion and cell clusters. However, we showed that IBC cells underwent epithelial-to-mesenchymal transition (EMT) and metastasized through EMT. Thus, there are two contradictory theories of IBC metastasis. The objectives of this study were 1) to propose a model that reconciles these two models, and 2) to identify target molecules for inhibition of IBC metastasis. Methods: We previously showed that Matrigel culture induced EMT-like changes in SUM149 IBC cells. To test if this transformation from epithelial (E) to mesenchymal (M) in Matrigel culture is unique to IBC cells, a panel of breast cancer cells was cultured in both monolayer and Matrigel-coated plates. The cells were IBC (SUM149, SUM190, KPL4, IBC3), triple-negative breast cancer (TNBC) (MDA-MB-231, MDA-MB-468), and ER+ (MCF7) cells. Phenotypic changes in morphology and expression of EMT markers (E-cadherin, vimentin) were captured with bright field and immunofluorescent (IF) images, respectively. For genome-wide and targeted transcriptional analysis, SUM149 cells cultured in monolayer and Matrigel were processed using DNA microarrays and Taqman qRT-PCR. To correlate the Matrigel gene signature with M features in human breast cancer, a human breast cancer data set was hierarchically clustered with the Matrigel gene signature. Results: SUM149 cells showed a remarkable phenotypic change from E in monolayer culture to M in Matrigel. IF analysis confirmed induction of vimentin expression in Matrigel but stable expression of E-cadherin (thus, we refer to this state as E/M hybrid). This trend was also observed with SUM190 cells. Using qRT-PCR, we confirmed downregulation of E-cadherin and upregulation of M markers (vimentin, Twist1, Snail1, ZEB2) in Matrigel-cultured SUM149 and SUM190 cells compared to monolayer-cultured cells. DNA microarray transcriptional analysis confirmed this trend in SUM149 cells. TNBC has more M-like features than other breast cancer subtypes. Given this evidence, we clustered human breast cancer data using overexpressed genes in Matrigel-cultured SUM149 cells. We identified a cluster of 20 genes in TNBC samples and, assuming that these genes are drivers of E to E/M transition, chose the inflammation-related gene CSF1 as a candidate. The CSF1/CSF1R axis was inhibited by a CSF1R inhibitor, BLZ945; moreover, treatment with BLZ945 reversed the EMT changes in cells in Matrigel culture. Treatment with 5 μM BLZ945 re-induced E-cadherin expression and suppressed Snail1 and Twist1 expression in Matrigel-cultured SUM149 cells. Conclusion: IBC cells are more prone to undergo transition from E to E/M phenotype in Matrigel culture than are cells of other breast cancer subtypes. The CSF1/CSF1R axis plays a role in this E to E/M transition, thus warranting testing its significance using an in vivo IBC model. Phenotypic transition and reversion between E and E/M phenotypes could be a new paradigm that reconciles two contradictory models of IBC metastasis.

Citation Format: Kai K, Iwamoto T, Zhang D, Rao AUK, Thompson A, Sen S, Ueno NT. CSF1/CSF1R axis reprograms epithelial-to-mesenchymal phenotypes in inflammatory breast cancer [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P4-14-02.

Endogenous Hydrogen Sulfide Contributes to Tone Generation in Porcine Lower Esophageal Sphincter Via Na+/Ca2+ Exchanger

BACKGROUND AND AIMS

Hydrogen sulfide (H₂S) is a major physiologic gastrotransmitter. Its role in the regulation of the lower esophageal sphincter (LES) function remains unknown. The present study addresses this question.

METHODS

Isometric contraction was monitored in circular smooth muscle strips of porcine LES. Changes in cytosolic Ca²⁺ concentration ([Ca²⁺]_i) and force were simultaneously monitored in fura-2-loaded strips with front-surface fluorometry. The contribution of endogenous H₂S to LES contractility was investigated by examining the effects of inhibitors of H₂S-generating enzymes, including cystathionine-β-synthase, cystathionine-γ-lyase, and 3-mercaptopyruvate sulfurtransferase, on the LES function.

RESULTS

Porcine LES strips myogenically maintained a tetrodotoxin-resistant basal tone. Application of AOA (cystathionine-β-synthase inhibitor) or L-aspartic acid (L-Asp; 3-mercaptopyruvate sulfurtransferase inhibitor) but not DL-PAG (cystathionine-γ-lyase inhibitor), decreased this basal tone. The relaxant effects of AOA and L-Asp were additive. Maximum relaxation was obtained by combination of 1 mM AOA and 3 mM L-Asp. Immunohistochemical analyses revealed that cystathionine-β-synthase and 3-mercaptopyruvate sulfurtransferase, but not cystathionine-γ-lyase, were expressed in porcine LES. AOA+L-Asp-induced relaxation was accompanied by a decrease in [Ca²⁺]_i and inversely correlated with the extracellular Na⁺ concentration ([Na⁺]_o) (25-137.4 mM), indicating involvement of an Na⁺/Ca²⁺ exchanger. The reduction in the basal [Ca²⁺]_i level by AOA was significantly augmented in the antral smooth muscle sheets of Na⁺/Ca²⁺ exchanger transgenic mice compared with wild-type mice.

CONCLUSIONS

Endogenous H₂S regulates the LES myogenic tone by maintaining the basal [Ca²⁺]_i via Na⁺/Ca²⁺ exchanger. H₂S-generating enzymes may be a potential therapeutic target for esophageal motility disorders, such as achalasia.

Shortest Double-Walled Carbon Nanotubes Composed of Cycloparaphenylenes

Invited for this month's cover is the group of Prof. Dr. Shigeru Yamago at the Kyoto University (Japan). The image shows the host-guest possibilities of cycloparaphenylenes (CPPs) of different sizes. Size selective interaction between [n]CPP and [n+5]CPP affords a host-guest complex, [n+5]CPP⊃[n]CPP, which is the shortest double-walled armchair carbon nanotube. The size-selective complex formation illustrates the importance of van der Waals interactions. A ternary complex, [15]CPP⊃[10]CPP⊃C₆₀ , also forms from [15]CPP, [10]CPP, and C₆₀ . Read the full text of the article at 10.1002/cplu.201700097.

Shortest Double-Walled Carbon Nanotubes Composed of Cycloparaphenylenes

The host-guest chemistry of cycloparaphenylenes (CPPs) of different sizes is described. [n]CPPs (n=5, 6, 7, 8, and 10) selectively interact with [n+5]CPPs, forming complexes [n+5]CPP⊃[n]CPP, which are the shortest double-walled armchair carbon nanotubes. The size selectivity is dictated by the difference in diameters of the CPPs (that is, 0.34-0.35 nm), which maximizes attractive van der Waals interactions. Theoretical calculations suggest that the orbital energies of the CPPs become perturbed upon complex formation, and orbital mixing between the two CPPs is predicted for large CPP pairs. The association constants in 1,1,2,2-[D₂ ]tetrachloroethane, estimated by ¹ H NMR titration, are approximately 10³  mol L^-1 at 50 °C. Van't Hoff plot analysis reveals that complexation is driven mainly by entropy owing to desolvation of the CPPs. [13]CPP also forms a complex with [4]cyclo-2,7-pyrenylene ([4]CPY), which is a π-extended [8]CPP. Theoretical calculations suggest that the formation of [13]CPP⊃[4]CPY is more exothermic than that of [13]CPP⊃[8]CPP. A ternary complex, [15]CPP⊃[10]CPP⊃C₆₀ , is also formed by mixing [15]CPP and [10]CPP⊃C₆₀ .

A subset of cerebrovascular pericytes originates from mature macrophages in the very early phase of vascular development in CNS

Pericytes are believed to originate from either mesenchymal or neural crest cells. It has recently been reported that pericytes play important roles in the central nervous system (CNS) by regulating blood-brain barrier homeostasis and blood flow at the capillary level. However, the origin of CNS microvascular pericytes and the mechanism of their recruitment remain unknown. Here, we show a new source of cerebrovascular pericytes during neurogenesis. In the CNS of embryonic day 10.5 mouse embryos, CD31⁺F4/80⁺ hematopoietic lineage cells were observed in the avascular region around the dorsal midline of the developing midbrain. These cells expressed additional macrophage markers such as CD206 and CD11b. Moreover, the CD31⁺F4/80⁺ cells phagocytosed apoptotic cells as functionally matured macrophages, adhered to the newly formed subventricular vascular plexus, and then divided into daughter cells. Eventually, these CD31⁺F4/80⁺ cells transdifferentiated into NG2/PDGFRβ/desmin-expressing cerebrovascular pericytes, enwrapping and associating with vascular endothelial cells. These data indicate that a subset of cerebrovascular pericytes derive from mature macrophages in the very early phase of CNS vascular development, which in turn are recruited from sites of embryonic hematopoiesis such as the yolk sac by way of blood flow.

Reduced CaM Kinase II and CaM Kinase IV Activities Underlie Cognitive Deficits in NCKX2 Heterozygous Mice

Among five members of the K⁺-dependent Na⁺/Ca²⁺ exchanger (NCKX) family (NCKX1-5), only NCKX2 is highly expressed in mouse brain. NCKX2 in plasma membranes mediates cytosolic calcium excretion through electrogenic exchange of 4 Na⁺ for 1 Ca²⁺ and 1 K⁺. Here, we observed significantly decreased levels of NCKX2 protein and mRNA in the CA1 region of APP23 mice, a model of Alzheimer's disease. We also found that, like APP23 mice, heterozygous NCKX2-mutant mice exhibit mildly impaired hippocampal LTP and memory acquisition, the latter based on novel object recognition and passive avoidance tasks. When we addressed underlying mechanisms, we found that both CaMKII autophosphorylation and CaMKIV phosphorylation significantly decreased in CA1 regions of NCKX2+/- relative to control mice. Likewise, phosphorylation of GluA1 (Ser-831) and CREB (Ser-133), respective downstream targets of CaMKII and CaMKIV, also significantly decreased in the CA1 region. BDNF protein and mRNA levels significantly decreased in CA1 of NCKX2+/- relative to control mice. Finally, CaN activity increased in CA1 of NCKX2+/- mice. Our findings suggest that like APP23 mice, NCKX2+/- mice may exhibit impaired learning and hippocampal LTP due to decreased CaM kinase II and CaM kinase IV activities.