[Effects of tetrandrine on proliferation and activation of cardiac fibroblasts]

OBJECTIVE

To investigate the effects of tetrandrine (Tet) on proliferation and activation of rat cardiac fibroblasts.

METHODS

Firstly, the cell counting kit-8 (cck-8) assay was applied to detect the effects of Tet with different concentrations on proliferation of cardiac fibroblasts. Secondly, transforming growth factor (TGF-β)with a concentration of 5 μg/L was used to induce the cardiac fibroblast activation, and Western blot was performed to measure the expression variation of β-catenin, vimentin (Vm), fibronectin (Fn) and smooth muscle α-actin (SMA). At last, the real-time PCR was conducted to measure the expression change of collagen-1(Col-1) and collagen-3(Col-3).

RESULTS

The cck-8 assay showed that the Tet with different concentrations respectively, which were 0.5 μmol/L, 1 μmol/L, 2 μmol/L, 4 μmol/L, and 8 μmol/L, significantly inhibited the proliferation of cardiac fibroblasts. The viability was decreased to 94.4%,84.9%,74.9%,63.8%and 50.3% respectively of the control group when the Tet concentration changed, and the difference was statistically significant, P=0.043, P<0.001, P<0.001, P<0.001, P<0.001 respectively. Western blot revealed that the expressions of β-catenin, Fn, SMA and Vm, were up-regulated by TGF-β(5 μg/L), the result showed that the difference was statistically significant, and the P values were 0.001,0.008,0.010,0.001 respectively. Then, the up-regulation of β-catenin, Fn and SMA was attenuated by pre-treatment of Tet, and the result also displayed that the difference was statistically significant, and the P values were 0.009, 0.005, 0.019,respectively. While there was no significant change in the expression of Vm, according to Western blotting, and P>0.05,at the same time, real-time PCR indicated that the up-regulations of Col-1 and Col-3 which were induced by TGF-β were blocked by pre-treatment of Tet, the result showed that the difference was statistically significant, P<0.001.

CONCLUSION

According to the experimental results, we can draw the conclusion that: the Tet can significantly inhibit the proliferation of cardiac fibroblasts, meanwhile, it can block the activation of cardiac fibroblasts, which is induced by TGF-β. It is supposed that the Tet may probably have anti myocardial fibrosis, which indicates that it may probably be a medicine which is used to block the cardiac remodeling.

Abstract P2-02-06: Biomarker analysis by next generation circulating tumor DNA (ctDNA) sequencing in patients with advanced breast cancer

Background: Next-generation sequencing is of increasing interest to identify specific targets for both drug development and treatment. The study of metastatic cancer is complicated by lack of tissue and the potential for change in biology over treatment. We evaluated ctDNA in patients with advanced breast cancer to explore the relationship between specific DNA mutations and prognosis as well as therapeutic decision making.

Methods:Peripheral blood was collected in EDTA at the time of diagnosis of advanced disease. Samples were sent to Geneplus-Beijing for sequencing. Indexed Illumina libraries were prepared from germline and circulating DNA using the KAPA Library Preparation Kit; the capture probe was designed based on genomic regions selected with 1021 genes, covering the most frequently mutated genes and exons in solid tumors. Clinical characteristics, treatment and outcome data were collected. We analyzed progression free survival (PFS) from first-line therapy and overall survival (OS), endpoints were correlated with observed gene mutations.

Results: 54 patients were enrolled; 27 (50%) HER2+, 22 (41%) hormone receptor + (HR+)/HER2-, and 5 (9%) triple negative (TNBC). Median age was 48 (range 26-74). The median follow-up was 8 years (range 12-180 months). First-line therapy included chemotherapy with trastuzumab for HER2+ disease, chemotherapy with endocrine maintenance (17) or endocrine therapy alone (5) for HR+/HER2- disease, and chemotherapy for TNBC. Mutations were found in TP53, PIK3CA, PIK3CA 3140 A&gt;G(p.H1047R) and ERBB (including ERBB1-4), at 40.7%, 35.2%, 20.4% and 25.9%, respectively. In univariate analysis, patients with tumor mutations in TP53 had a shorter OS (median 64 vs 121 months, p=0.006). The PIK3CA 3140 A&gt;G mutation was more frequent in HER2+ (7/27, 25.9%) than HR+/HER2- (4/22 (18.2%) or TNBC (0/5), and was associated with shorter median PFS in HER2+ disease (mutant vs. wild type: 4 (range 2-9) vs. 8 (range 2-22) months, p=0.006). The frequency of ERBB mutation was similar in HER2- 7/27(25.9%) (p=0.707) or HER2+ 7/27(25.9%) disease (p=0.066); there was no significant impact on PFS in any subset. Multivariate analysis for HER2+ disease including age, ER, Ki67, TP53, PIK3CA, PIK3CA 3140 A&gt;G and ERBB), demonstrated that the PIK3CA 3140 A&gt;G mutation was the only factor associated with shorter PFS (p=0.025); further analysis by receiver operating characteristic (ROC) curve showed that the PIK3CA 3140 A&gt;G mutation and the mutation in PIK3CA 3140 A&gt;G and ERBB combination pathway had a large area under the curve (AUC), with AUC of 0.789, and 0.734 respectively.

Conclusions: Using NGS in ctDNA, we found that the PIK3CA 3140A&gt;G mutation was more frequent in HER2+ disease, and was the only mutation associated with shorter PFS on multivariate analysis. The presence of a TP53 mutation was associated with worse OS. Evaluation of ctDNA is feasible in a general breast cancer population and has prognostic impact; further correlation of these findings with tumor samples is ongoing.

Citation Format: Li H, Wang J, Rugo HS, Zhang Y, Yang L, Liu X, Shao B, Xu Y, Yang L, Zhang R, Ran R, Chang L. Biomarker analysis by next generation circulating tumor DNA (ctDNA) sequencing in patients with advanced 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 P2-02-06.

Colonic immune cells in irritable bowel syndrome: A systematic review and meta-analysis

BACKGROUND & AIMS

Increases in mucosal immune cells have frequently been observed in irritable bowel syndrome (IBS) patients. However, this finding is not completely consistent between studies, possibly due to a combination of methodological variability, population differences and small sample sizes. We performed a meta-analysis of case-control studies that compared immune cell counts in colonic biopsies of IBS patients and controls.

METHODS

PubMed and Embase were searched in February 2017. Results were pooled using standardized mean difference (SMD) and were considered significant when zero was not within the 95% confidence interval (CI). Heterogeneity was assessed based on I² statistics where I²  ≤ 50% and I²  > 50% indicated fixed and random effect models, respectively.

KEY RESULTS

Twenty-two studies on 706 IBS patients and 401 controls were included. Mast cells were increased in the rectosigmoid (SMD: 0.38 [95% CI: 0.06-0.71]; P = .02) and descending colon (SMD: 1.69 [95% CI: 0.65-2.73]; P = .001) of IBS patients. Increased mast cells were observed in both constipation (IBS-C) and diarrhea predominant IBS (IBS-D). CD3⁺ T cells were increased in the rectosigmoid (SMD: 0.53 [95% CI: 0.21-0.85]; P = .001) and the descending colon of the IBS patients (SMD: 0.79, 95% CI [0.28-1.30]; P = .002). This was possibly in relation to higher CD4⁺ T cells in IBS (SMD: 0.33 [95% CI: 0.01-0.65]; P = .04) as there were no differences in CD8⁺ T cells.

CONCLUSIONS & INFERENCES

Mast cells and CD3⁺ T cells are increased in colonic biopsies of patients with IBS vs non-inflamed controls. These changes are segmental and sometimes IBS-subtype dependent. The diagnostic value of the quantification of colonic mucosal cells in IBS requires further investigation.

Decline of insulin therapy and delays in insulin initiation in people with uncontrolled diabetes mellitus

AIMS

To design and validate a natural language processing algorithm to identify insulin therapy decline from the text of physician notes, and to determine the prevalence of insulin therapy decline and its impact on insulin initiation.

METHODS

We designed the algorithm using the publicly available natural language processing platform Canary. We evaluated the accuracy of the algorithm on 1501 randomly selected primary care physicians' notes from the electronic medical record system of a large academic medical centre. Using the validated language model, we then studied the prevalence of insulin therapy decline between 2000 and 2014.

RESULTS

The algorithm identified documentation of insulin therapy decline with a sensitivity of 100% (95% CI 82.4-100), a positive predictive value of 95% (95% CI 74.4-99.9), and a specificity of 99.9% (95% CI 99.6-100.0). We identified 3295 insulin-naïve adults with Type 2 diabetes who were recommended insulin therapy; 984 of them (29.9%) initially declined insulin. People with HbA_1c ≥ 75 mmol/mol (9.0%) were more likely [766/2239 (34.2%)] to have declined insulin than people with HbA_1c 53-63 mmol/mol (7.0-7.9%) and 64-74 mmol/mol (8.0-8.9%; P < 0.0001). Among the people who initially declined but ultimately started insulin [374/984 (38.0%)], mean time to insulin initiation was 790 days.

CONCLUSIONS

Insulin therapy decline is common, potentially leading to progression of hyperglycaemia and a delay in achievement of glycaemic control. Further investigation is needed to determine the reasons, risk factors and long-term outcomes of this important clinical phenomenon.

[A case report: Ramsay Hunt syndrome with throat as starting place merger ipsilateral cranial nerver involvement]

The clinical data of a case of Ramsay Hunt syndrome concurrent with ipsilateral Ⅴ, Ⅶ, Ⅷ, Ⅸ, Ⅹ, Ⅺ cranial nerves paralysis with throat as starting place was retrospectively analyzed, and the relevant literatures were also reviewed. The case is rare, so the relevant clinical reports are less. It is important to take the objective data as well as subjective symptoms of the patients into consideration to make a definite diagnosis, so that we can treat it as soon as possible to achieve better curative effect.

Observation of whispering gallery modes through electron beam-induced deposition

Surprisingly intense spectra of whispering gallery modes were observed in polymer microbeads after illumination with electrons in a scanning electron microscope and subsequent laser illumination and spectral analysis. It will be proposed that whispering gallery mode resonances became visible after local deposition of hydrocarbon material through electron beam-induced deposition. The illumination of deposited material with a near infrared laser generates a broad light spectrum, acting as a local "white light" source that couples, for favorable wavelengths, with the WGM sustained by the sphere. This facilitates a spectroscopic analysis of the WGM and provides the Q-factor and free spectral range for all investigated particles. The analysis by an integrated SEM and Raman micro-spectrometer offers a direct approach to the analysis of WGM resonators as they are, for instance, used in sensing.

Abstract P1-10-02: A signature predictive of early vs. late recurrence after radiation treatment (RT) for breast cancer that may inform the biology of early, aggressive recurrences

Purpose: Unmet clinical needs in breast cancer (BC) management include the identification of patients (pts) at high risk to fail locally despite standard local therapy including RT and understanding the biology of these recurrences. We previously reported1 a RT response signature and here extend those studies to identify a signature predictive of timing of recurrence after completion of RT (before or after 3 years).

Methods: Two independent patient cohorts (treated with BCS) from non-randomized clinical trials were used for training and validation. The training cohort included 119 pts with in-breast tumor recurrence and the validation cohort had 25 pts with recurrences. Initial feature selection used Spearman's rank correlation correlating gene expression (14,806 genes) to recurrence time. Genes with sig. correlation (FDR &lt;0.1) and large expression range (fold change &gt;2) were used to train an elastic net penalized Poisson regression model. This model was locked and then applied to the validation dataset. Cox regression was used for both univariate and multivariable analyses (UVA and MVA). To identify biological-related concepts, Spearman's corr. coefficients of recurrence time to gene expression within the training cohort were used to generate a pre-ranked list upon which GSEA pathway analysis was performed.

Results: Spearman's correlation identified 485 genes whose expression was significantly associated with recurrence time (early vs. late). Feature reduction further refined the gene list to 41 genes, which were retained within the signature and locked for further validation. In the training dataset the Spearman's correlation of the continuous score to recurrence time was 0.852 with a P-value of 1.3x10-34 and an AUC of 0.92. Application of this early vs late signature to an independent BC validation set accurately identifies pts with early vs. late recurrences (Spearman's corr.=0.537, p-value&lt;0.007, AUC=0.74, sensitivity=0.71, specificity=0.73, PPV=0.77, NPV=0.67). In UVA and MVA the early vs. late recurrence signature remained the most significant factor associated with recurrence time. Although independent of intrinsic subtype, GSEA analysis of the 41 genes retained within the signature identifies proliferation and EGFR concepts associated with early recurrences and luminal and ER-signaling pathways associated with late recurrences. Knockdown of genes associated with the early and late recurrences is currently underway to assess phenotypic changes (proliferation and clonogenic survival as a measure of early and durable RT response) associated with the early and late recurrence-associated genes.

Conclusion: In this study we derive a BC-specific RT signature predictive of early vs. late recurrence with biologic relevance and validate this signature for prediction of timing of recurrence in an independent clinical dataset. By identifying pts with tumors likely to recur sooner vs. later this signature has the potential to allow for a furthered understanding of the biology underlying early and late recurrences and has a potential to personalize RT, particularly in patients for whom treatment intensification is needed.

1. Clin Cancer Res. 2015 Aug 15;21(16):3667-77.

Citation Format: Speers C, Chang L, Santola A, Liu M, Zhao SG, Chandler B, Olsen E, Bartelink H, Feng FY, Pierce LJ. A signature predictive of early vs. late recurrence after radiation treatment (RT) for breast cancer that may inform the biology of early, aggressive recurrences [abstract]. In: Proceedings of the 2016 San Antonio Breast Cancer Symposium; 2016 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2017;77(4 Suppl):Abstract nr P1-10-02.

miR-26a-5p suppresses tumor metastasis by regulating EMT and is associated with prognosis in HCC

OBJECTIVE

To determine the role of miR-26a-5p in tumor invasion and metastasis in hepatocellular carcinoma (HCC).

METHODS

We evaluated miR-26a-5p expression in HCC tissues by quantitative PCR and then analyzed its clinical significance using a Cox regression model. Transwell and nude mouse models were used to examine tumor metastasis in vitro and in vivo, respectively. The relationship between miR-26a-5p and epithelial-mesenchymal transition was also investigated by q-PCR and western blot.

RESULTS

Strong downregulation of miR-26a-5p was observed in tumor tissues compared to paired adjacent normal tissues. Moreover, patients with low miR-26a-5p expression had a significantly poorer prognosis than those with high expression. The multivariate analysis indicated that miR-26a-5p expression was an independent prognostic indicator. The experimental transwell model and athymic mouse model revealed that miR-26a-5p depressed tumor metastasis in vitro and in vivo, respectively. In addition, the decreased miR-26a-5p level observed in HCC was associated with reduced E-cadherin expression and upregulation of vimentin, which affects the molecular mechanism of EMT.

CONCLUSION

Downregulation of miR-26a-5p promotes tumor metastasis by targeting EMT and influences the prognosis of HCC patients. Therefore, miR-26a-5p has potential as a new biomarker and therapeutic target.

[Effects of oral interventions on carotid artery, serum C-reactive protein and interleukin 6 in chronic periodontitis rats with atherosclerosis]

Objective: To explore the effect of variousoral interventions on the development of atherosclerosis in SD rats with chronic periodontitis and atherosclerosis. Methods: Forty-four male SD rats were randomly divided into three groups, Group A(healthycontrol), Group B(atherosclerosis, As) and Group C(chronic periodontitis with atherosclerosis, CP+As). Rats in Group C were further divided randomly into Subgroup C1(natural process, n=7), Subgroup C2(mechanical therapy, n=7), Subgroup C3(systemic antibiotic treatment, n=7) and Subgroup C4(tooth extraction, n=7). Rats in each subgroup of Group C received one of the appropriate oral interventions. The pathological lesions of carotid artery plaque were stained with hematoxylin and eosin(HE) and observed under a light microscope. The serum levels of C-reactive protein(CRP) and interleukin-6(IL-6) were detected by enzyme-linked immunosorbent assay (ELISA) in five different time points. Results: Pathological results showed that increased foam cells and inflammatory cells were found in Group B. Irregular vessel wall, inflammatory cell, the foam cells, disordered elastic fibers were observed in Group C. While fewer in flammatory cells were found in Subgroup C2 than that in other subgroups. The changing trends of the serum levels of CRP and IL-6 were consistant with time went by. The levels of serum CRP, IL-6 in Groups B and C were significantly higher than that in Group A at all time points(P<0.01). The levels of serum CRP, IL-6 in Subgroup C1 became higher gradually(P<0.05) with time being. The serum levels after oral interventions changed significantly compared with the baseline levels(P<0.05). One week after the second round of intervention, the serum levels of CRP(C2: [9.43 ± 1.28] μg/L, C3: [12.38±0.81] μg/L, C4: [15.76±1.03] μg/L) and IL-6 (C2: [94.71±16.09] μg/L, C3: [112.89± 40.16] μg/L, C4: [175.11 ± 50.79] μg/L) in intervention subgroups reached the peaksand were significantly higher than that of Group B(CRP: [6.96±1.30] μg/L, IL-6: [43.36±7.46] μg/L) and Subgroup C1(CRP: [8.41± 0.46] μg/L, IL-6: [73.59±27.89] μg/L)(P<0.05). The changes of serum levels then declined with time beingin each group/subgroupand level in Subgroup C2 was the lowest(P<0.01). Conclusions: In chronic periodontitis of rats with atherosclerosis, permanent periodontitis mightsignificantly raise the risk of the development of atherosclerosis. Oral interventions increased the risk of atherosclerosis in a short period of time because of increased levels of serum inflammatory factors, but effective improvement could be observed on the As lesions after oral interventions in along term, especially after the periodontal mechanical therapy.

Effects of baseline abdominal pain and bloating on response to lubiprostone in patients with irritable bowel syndrome with constipation

BACKGROUND

Lubiprostone (8 μg b.d.) received US Food and Drug Administration (FDA) approval in 2008 for the treatment of constipation-predominant irritable bowel syndrome (IBS-C) in women aged ≥18 years. In 2012, the FDA issued new guidance for IBS-C clinical trials, recommending a composite endpoint incorporating both abdominal pain and stool frequency.

AIM

In a post hoc analysis, similar criteria were applied to data from two pivotal, phase 3, double-blind, randomised trials of lubiprostone in patients with IBS-C.

METHODS

Included patients had a baseline spontaneous bowel movement (SBM) frequency <3/week and abdominal pain or bloating ratings ≥1.36 on a 5-point scale [0 (absent) to 4 (very severe)]. Responders (composite endpoint) had a mean pain reduction ≥30% compared with baseline, and an increase from baseline of ≥1 SBM/week for ≥6 of the 12 treatment weeks. Lubiprostone effects on abdominal pain alone were also evaluated, as were bloating alone and in a composite endpoint with stool frequency.

RESULTS

In pooled data, 325 patients received lubiprostone and 180 received placebo. Rates of response were higher with lubiprostone vs. placebo for the composite endpoint of improved pain and stool frequency (26.3% vs. 15.3%, respectively; P = 0.008) and the composite endpoint of improved bloating and stool frequency (23.8% vs. 12.6%, respectively; P = 0.012). Response rates were also higher with lubiprostone vs. placebo for abdominal pain alone (P = 0.005) and bloating alone (P = 0.012).

CONCLUSION

Lubiprostone was significantly more effective than placebo in improving abdominal pain or bloating, and also in composite endpoints that included stool frequency.

Cardiac damage and dysfunction in diabetic cardiomyopathy are ameliorated by Grx1

Glutaredoxin 1 (Grx1) has been found to be an important endogenous antioxidant enzyme closely related to the pathogenesis of diabetes and cardiovascular diseases caused by oxidative stress. In this study, the functional changes of the Grx1 redox system in blood of hyperglycemic patients were examined. Furthermore, using a rat model of streptozotocin (STZ)- and high-fat-diet-induced type 2 diabetes, we explored the correlation between functional changes of the Grx1 redox system in the left ventricular tissue and blood of the diabetic rats. Moreover, we studied the protective effect of Grx1 against cardiac toxicity caused by the high-glucose-induced expression of cardiac matrix metalloproteinases (MMPs) in primary cultured cardiac fibroblasts. Finally, we investigated the protective effects and signaling regulatory mechanism of Grx1 against diabetic cardiomyopathy (DCM) in terms of oxidative stress and NF-kB-mediated fibrosis-associated signaling pathways. In the serum of hyperglycemic patients, Grx1 levels were elevated, total/protein thiol or sulfhydryl (Total-SH/P-SH) levels were decreased, glutathione was downregulated, and oxidized glutathione was upregulated. In addition, in the left ventricular myocardium and blood of the diabetic rats, Grx1 levels were significantly increased and glutathione reductase and P-SH levels were decreased. Moreover, endogenous Grx1 was highly expressed in cardiac fibroblasts during high-glucose treatment, and exogenous Grx1 can prevent DCM by controlling oxidative damage and MMP expression. These findings are suggestive of changes in the Grx1 redox system, and Grx1-regulated protein oxidative modifications may serve as molecular markers for diabetes caused by high-glucose-induced oxidative stress.

Adverse childhood experiences are associated with irritable bowel syndrome and gastrointestinal symptom severity

BACKGROUND

Early adverse life events (EALs) are associated with irritable bowel syndrome (IBS). Exposure to EALs as assessed by the Adverse Childhood Experiences (ACE) questionnaire is associated with greater disease prevalence, but ACE has not been studied in gastrointestinal disorders. Study aims were to: (i) Estimate the prevalence of EALs in the IBS patients using the ACE questionnaire; (ii) Determine correlations between ACE and Early Trauma Inventory Self Report-Short Form (ETI-SR) scores to confirm its validity in IBS; and (iii) Correlate ACE scores with IBS symptom severity.

METHODS

A total of 148 IBS (73% women, mean age = 31 years) and 154 HCs (59% women, mean age = 30 years) completed the ACE and ETI-SR between June 2010 and April 2015. These surveys measured EALs before age 18 in the domains of physical, sexual, and emotional abuse, and general trauma. IBS and abdominal pain severity was measured by a 20-point scale (0 = none, 20 = worst symptoms).

KEY RESULTS

The ACE score increased the odds of having IBS (odds ratio [OR] = 2.05, 95% confidence interval [CI]: 1.21-3.48, p = 0.008). Household mental illness (p < 0.001), emotional abuse (p = 0.004), and incarcerated household member (p = 0.019) were significant predictors of IBS. Adverse childhood experiences and ETI-SR scores were strongly correlated (r = 0.59, p < 0.001). ACE, but not ETI-SR, modestly correlated with IBS severity (r = 0.17, p = 0.036) and abdominal pain (r = 0.20, p = 0.015).

CONCLUSIONS & INFERENCES

The ACE questionnaire is a useful instrument to measure EALs in IBS based on its use in large studies, its ability to measure prevalence across different EAL domains, and its correlation with symptom severity.

Inhibitory effects of bevacizumab monoclonal antibodies in combination with chemotherapy in different time sequences on a human gastric carcinoma cell line

OBJECTIVE

This study investigated the inhibitory effects of bevacizumab monoclonal antibodies in combination with chemotherapy in different time sequences on a human gastric cancer cell line (MGC-803).

METHODS

Cultured MGC-803 human gastric cancer cells were treated with bevacizumab in combination with chemotherapy treatment in different time sequences. The effects on cell growth inhibition were determined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell cycle distribution and the rate of cell apoptosis were determined by propidium iodide staining followed by flow cytometry.

RESULTS

Drug administration for different time sequences significantly inhibited the growth of MGC-803 cells. Based on group comparisons (P < 0.01), the effect of 24 h bevacizumab treatment prior to combination 5-fluorouracil and cisplatin (FP) was the strongest (F = 241.313, 246.856, all P values <0.001). Treating MGC-803 cells with bevacizumab for 24 h before combination FP induced significant G2/M phase arrest (F = 231.991, P < 0.001) and significantly increased gastric cancer cell apoptosis. Bevacizumab in combination with chemotherapy significantly inhibits the proliferation of MGC-803 gastric cancer cells.

CONCLUSIONS

The mechanism may be related to cell cycle arrest at S phase and the induction of apoptosis in MGC-803 gastric cancer cells.

Growth and stability of rocksalt Zn1-xMgxO epilayers and ZnO/MgO superlattice on MgO (100) substrate by molecular beam epitaxy

Zn1-xMgxO films with x = 0.04-0.50 grown on MgO (100) substrates by molecular beam epitaxy retain the rocksalt (rs) crystal structure and grow epitaxially for x ≥ 0.17. In addition, the rs-ZnO epilayer is observed to be stable up to a thickness of 5 nm and also in a ZnO/MgO superlattice sample. However, a portion of the superlattice has transformed to wurtzite (wz)-structure islands in a self-accommodated manner during growth. The transformation is a combination of a Bain distortion, an in-plane rotation of 14.5°, and a Peierls distortion, resulting in an orientation relationship of (100)rs//(101̄0)wz and 〈011〉rs ∼//〈1̄21̄3〉wz. In such a manner, the volume expansion is only necessary along the growth direction and the in-plane strains can be minimized. A negative pressure generated during the transformation of ZnO stabilizes the MgO into a wurtzite structure.