The association of hematuria on kidney clinicopathologic features and renal outcome in patients with diabetic nephropathy: a biopsy-based study

PURPOSE

To investigate the relationships between hematuria, clinicopathological features and renal outcomes in patients with biopsy-proven diabetic nephropathy (DN).

METHODS

This cohort study included 261 patients with DN. Participants were divided into two groups according to number of red blood cells per high-power field (RBC/hpf) in urine sediment: the hematuria (-) group (≤ 3 RBC/hpf) and the hematuria (+) group (> 3 RBC/hpf). Basic clinical parameters were measured at the time of renal biopsy; relationships between hematuria and clinicopathological features and renal outcomes were analyzed.

RESULTS

Patients in the hematuria (+) group often had overt proteinuria. Interstitial inflammation was more severe in the hematuria (+) group than in the hematuria (-) group. Glomerular arteriolar hyalinosis, interstitial fibrosis and tubular atrophy were comparable between groups. For patients with early DN (eGFR ≥ 60 ml/min/1.73 m²), urinary RBC/hpf at baseline was positively correlated with glomerular classification, interstitial fibrosis/tubular atrophy scores and interstitial inflammation scores. In prognostic analysis, hematuria was associated with a higher risk of progression to end-stage renal disease. Hematuria remained an independent predictor after adjustment for confounding factors such as sex, age, duration of diabetes, serum glucose level, hypertension, cholesterol, eGFR and urine protein excretion, especially in patients with early DN and in male patients.

CONCLUSION

In this study, hematuria was associated with more severe renal pathologic lesions in patients with DN. The presence of hematuria could be an independent predictor of renal outcome in patients with early DN.

Characterization of on-target adverse events caused by TRK inhibitor therapy

BACKGROUND

The tropomyosin receptor kinase (TRK) pathway controls appetite, balance, and pain sensitivity. While these functions are reflected in the on-target adverse events (AEs) observed with TRK inhibition, these AEs remain under-recognized, and pain upon drug withdrawal has not previously been reported. As TRK inhibitors are approved by multiple regulatory agencies for TRK or ROS1 fusion-positive cancers, characterizing these AEs and corresponding management strategies is crucial.

PATIENTS AND METHODS

Patients with advanced or unresectable solid tumors treated with a TRK inhibitor were retrospectively identified in a search of clinical databases. Among these patients, the frequency, severity, duration, and management outcomes of AEs including weight gain, dizziness or ataxia, and withdrawal pain were characterized.

RESULTS

Ninety-six patients with 15 unique cancer histologies treated with a TRK inhibitor were identified. Weight gain was observed in 53% [95% confidence interval (CI), 43%-62%] of patients and increased with time on TRK inhibition. Pharmacologic intervention, most commonly with glucagon-like peptide 1 analogs or metformin, appeared to result in stabilization or loss of weight. Dizziness, with or without ataxia, was observed in 41% (95% CI, 31%-51%) of patients with a median time to onset of 2 weeks (range, 3 days to 16 months). TRK inhibitor dose reduction was the most effective intervention for dizziness. Pain upon temporary or permanent TRK inhibitor discontinuation was observed in 35% (95% CI, 24%-46%) of patients; this was more common with longer TRK inhibitor use. TRK inhibitor reinitiation was the most effective intervention for withdrawal pain.

CONCLUSIONS

TRK inhibition-related AEs including weight gain, dizziness, and withdrawal pain occur in a substantial proportion of patients receiving TRK inhibitors. This safety profile is unique relative to other anticancer therapies and warrants careful monitoring. These on-target toxicities are manageable with pharmacologic intervention and dose modification.

The E2F1 transcription factor and RB tumor suppressor moonlight as DNA repair factors

The E2F1 transcription factor and RB tumor suppressor are best known for their roles in regulating the expression of genes important for cell cycle progression but, they also have transcription-independent functions that facilitate DNA repair at sites of damage. Depending on the type of DNA damage, E2F1 can recruit either the GCN5 or p300/CBP histone acetyltransferases to deposit different histone acetylation marks in flanking chromatin. At DNA double-strand breaks, E2F1 also recruits RB and the BRG1 ATPase to remodel chromatin and promote loading of the MRE11-RAD50-NBS1 complex. Knock-in mouse models demonstrate important roles for E2F1 post-translational modifications in regulating DNA repair and physiological responses to DNA damage. This review highlights how E2F1 moonlights in DNA repair, thus revealing E2F1 as a versatile protein that recruits many of the same chromatin-modifying enzymes to sites of DNA damage to promote repair that it recruits to gene promoters to regulate transcription.

[Efficacy and safety of early initiation of sacubitril-valsartan therapy in patients with acute decompensated heart failure]

Objective: To assess the efficacy and safety of the initiation of sacubitril-valsartan （ARNI） therapy, as compared with ACEI therapy, after hemodynamic stabilization among patients hospitalized for acute decompensated heart failure （ADHF）. Methods: A total of 199 hospitalized patients for ADHF in our department from January 2017 to June 2019 were included in this retrospective analysis. According to the medication early after hemodynamic stabilization, patients were divided into ARNI group (n=92) and ACEI group (n=107). Among the included patients, 61 patients with newly diagnosed heart failure at the time of admission were also divided into ARNI group (n=30) and ACEI group (n=31) according to the applied medication. Clinical baseline data and follow-up results of enrolled patients were collected through the electronic medical records at admission, outpatient and telephone follow-up. The primary effectiveness observation index was left ventricular ejection fraction (LVEF) and left ventricular end diastolic dimension (LVEDD) measured by echocardiography; the secondary observation index was death from any causes and hospitalization for heart failure. Safety outcomes were the incidences of symptomatic hypotension, worsening renal function, hyperkalemia, and angioedema. Results: The clinical baseline characteristics were similar between ARNI group and ACEI group（all P>0.05）. The duration of follow up was (15.2±6.5) months in all patients enrolled, (12.3±5.0) months in ARNI group, and (18.2±6.5) months in ACEI group. At the end of follow-up, prevalence of an absolute LVEF increase of more than 5% was 48.9% (45/92) in ANRI group and 25.2% (27/107) in ACEI group (P=0.001). Percent of LVEF increase to more than 50% was 17.4% (16/92) in ANRI group and 3.7% (4/107) in ACEI group (P=0.001). Percent of patients with more than 10 mm LVEDD reduction was 14.1% (13/92) in ANRI group and 3.7% (4/107) in ACEI group (P=0.009). All-cause mortality rate was 5.7% (5/88) in ARNI group and 15.3% (13/85) in ACEI group (P=0.038). Rate of re-hospitalization due to heart failure was 50% (46/92) in ARNI group and 71% (76/107) in ACEI group（P=0.002）.The rates of symptomatic hypotension, worsening renal function, hyperkalemia, and angioedema were similar between ARNI group and ACEI group (all P>0.05). In patients with first diagnosed heart failure，percent of LVEF increase to more than 50% was 30% (9/30) in ANRI group and 6.5% (2/31) in ACEI group (P=0.017). Percent of more than 10 mm LVEDD reduction was 26.7%(8/30) in ANRI group and 3.2%(1/31) in ACEI group (P=0.012). Percent of an absolute LVEF increase of more than 5% was 53.3% (16/30) in ANRI group and 51.6% (16/31) in ACEI group (P=0.893). Re-hospitalization due to heart failure was 23.3% (7/30） in ARNI group and 73.3% (11/31) in ACEI group（P<0.01）. Rate of all-cause death tended to be lower in patients receiving ARNI (3.4% (1/29)) as compared to patients receiving ACEI (13.0% (3/23), P=0.197）. Conclusions: Among patients with heart failure with reduced ejection fraction hospitalized for ADHF, the initiation of ARNI therapy after hemodynamic stabilization is associated with a more significant improvement of cardiac remodeling and pump function than ACEI therapy and satisfactory safety. In ADHF patients with first diagnosed heart failure, initiation of ARNI therapy after hemodynamic stabilization can more effectively improve cardiac remodeling and pump function than treatment with ACEI.

Utilizing quantitative multiplex immunofluorescence to characterize paracrine interactions within the tumor-immune landscape of metastatic melanoma

e15184

Background: Clinical responses to anti-PD1 immunotherapy in patients with metastatic melanoma (MM) remain challenging to predict. This clinical heterogeneity is also reflected in the tumor-immune microenvironment among patients and within a single tumor lesion. With the emergence of multiplex imaging platforms, defining complex phenotypes at single cell resolution has become possible. Here, we sought to objectively quantify paracrine tumor-immune interactions contributing to the variable clinical responses observed in patients receiving anti-PD1 therapy. Methods: Excisional lymph node (LN) biopsies were obtained from treatment-naïve patients with MM who underwent subsequent anti-PD1 therapy. A single 5µm section of LN tissue was used to assess a 42 analyte panel by multiplex immunofluorescence. From 30 LN samples, 418 fields of view (FOVs) were selected resulting in 14,360 high-resolution images of 4 anatomical subregions: tumor core, tumor-immune interface, tumor infiltrate and adjacent immune stroma. Following image processing, we developed an adaptive classification for tumor-centric cellular neighborhoods (TCCN) to identify and quantify critical paracrine interactions within the tumor-immune microenvironment. Results: Stratification based on responsiveness to anti-PD1 therapy resulted in 4 complete responders (CR) and 12 non-responders (NR) at 12-week follow-up. From 126 FOVs, we defined the cellular composition of 197,865 TCCN across patients based on clinical response and LN subregions. Overall, the percentage of TCCN devoid of any T cells, B cells or macrophages was significantly higher in NR compared to CR irrespective of subregion. However, other markers differentiated TCCN based on subregion. Specifically in CR, tumor core regions were enriched for CD8 T cells, while enrichment for B cells and endothelial cells was demonstrated at the tumor-immune interface. Strikingly, tumor infiltrate regions demonstrate robust immune reactivity with enrichment for M1 polarized macrophages, NK cells and B cells in CR compared to NR. Complete data from the 30 patient cohort across 418 FOVs will be presented. Conclusions: Taken together, this data suggests cellular composition of TCCN across subregions of the LN is dynamic within a single metastatic site. In this small cohort, we introduce a formalized stratification to quantify and classify critical paracrine interactions within the immune-tumor microenvironment with the potential to inform clinical responsiveness to therapy.

THE PI3K/Akt/mTOR Signaling Pathway Plays a Role in Regulating Autophagy in Mouse Oocytes During Vitrification-warming and in vitro Maturation

BACKGROUND

It has been shown that vitrified-warmed oocytes exhibit autophagic activation. However, its regulatory molecular mechanism of autophagy needs to be clarified.

OBJECTIVE

To determine the role of signaling pathway of PI3K/Akt/mTOR in the regulation of autophagy in oocytes during vitrification-warming and IVM.

MATERIALS AND METHODS

Oocytes from mice were vitrified-warmed and IVM. The expressions of LC3-II, Beclin-1, PI3K, Akt, and mTOR protein were determined. Moreover, the ATP level, viability of vitrified-warmed oocytes, and their developmental potential were measured.

RESULTS

At 6 h of incubation of warmed oocytes, the LC3-II and Beclin-1 expressions were markedly up-regulated, whereas PI3K, Akt, and mTOR proteins expressions were significantly down-regulated. In addition, autophagy inhibition significantly decreased ATP level, viability of oocytes, and their developmental potential.

CONCLUSION

Autophagy plays a protective role in the oocytes during vitrification-warming and IVM. The PI3K/Akt/mTOR pathway participated in regulating autophagy activity in oocyte during vitrification-warming and IVM.

Circular RNA circ-NT5C2 acts as a potential novel biomarker for prognosis of osteosarcoma

OBJECTIVE

Recent evidence suggests that circular RNAs (circRNAs) play important roles in multiple diseases, including cancer. Circ-NT5C2 was reported to be up-regulated in osteosarcoma. However, the clinical significance of circ-NT5C2 remains largely unclear. The aim of the current study was to investigate the value of circ-NT5C2 for the prognosis of patients with osteosarcoma.

PATIENTS AND METHODS

the expression of circ-NT5C2 in osteosarcoma tissues and corresponding normal tissues were explored by quantitative real-time polymerase chain reaction (qRT-PCR) experiments. The association of circ-NT5C2 expression with clinicopathological factors or the prognosis of osteosarcoma patients was also analyzed. Kaplan-Meier survival analysis was performed to analyze the association of circ-NT5C2 expression with overall survival (OS) and disease-free survival (DFS) of patients. Univariate and multivariate Cox-regression analyses were used to identify risk factors for poor prognosis.

RESULTS

Our data showed a significant increase of circ-NT5C2 expression in osteosarcoma tissues compared with adjacent normal bone tissues (p < 0.01). In addition, we found that the level of circ-NT5C2 in osteosarcoma was strongly correlated with clinical stage (p = 0.006) and distant metastasis (p = 0.001). Importantly, patients with high expression of circ-NT5C2 had a shorter OS (p = 0.006) and DFS (p = 0.001) than those with low expression of circ-NT5C2. Finally, Cox regression analyses showed that high circ-NT5C2 expression might be an independent prognostic parameter to predict poor prognosis.

CONCLUSIONS

Our findings indicated that circ-NT5C2 is significantly up-regulated in osteosarcoma tissues. Circ-NT5C2 may represent a new marker of prognosis in osteosarcoma.

[A single-center retrospective study on axillary evaluation in 1 557 breast ductal carcinoma in situ patients between 2006 and 2016]

Objectives: To examine the influence factors on axillary evaluation in ductal carcinoma in situ (DCIS) patients, and the prognosis of different choices of axillary evaluation in a single-center retrospective study. Methods: Totally 1 557 DCIS patients admitted in Department of Breast Surgery, Fudan University Shanghai Cancer Center from January 2006 to November 2016 were retrospectively enrolled. All patients were female. The median age was 49 years (range: 21 to 85 years). Surgical methods included modified radical mastectomy, simple mastectomy (with or without axillary evaluation) and breast conservation surgery (with or without axillary evaluation). Axillary evaluation included axillary lymph node dissection (ALND) and sentinel lymph node biopsy (SLNB). T tests, χ(2) test and Logistic regression analysis was used to analyze influence factors on axillary evaluation, respectively. Kaplan-Meier curve and Log-rank analysis were used to evaluate recurrence-free survival (RFS) and loco-regional recurrence-free survival (LRRFS) in patients with different surgical methods. Results: Among the 1 557 DCIS patients, there were 1 226 cases received axillary evaluation, while 331 cases not received axillary evaluation. Patients were separated into 3 groups by different axillary evaluation choices: SLNB group (957 cases, 61.46%), ALND group (197 cases, 12.65%) and no evaluation group (403 cases, 25.88%). The patients in SLNB group increased significantly (P=0.000), from 3.85% (60/1 557) in 2006 to 75.19% (1 170/1 557) in 2016. The independent influence factors of receiving axillary evaluation were high nuclear grade (OR=3.191, 95%CI: 1.722 to 5.912, P=0.001) and tumor size>15 mm (OR=1.698, 95%CI: 1.120 to 2.573, P=0.012). Also, patients received breast conservation surgery were more likely to refuse axillary evaluation (OR=0.155, 95%CI: 0.103 to 0.233, P=0.000). There were no significant differences in RFS and LRRFS in patients with different axillary evaluation choices. Conclusions: The investigation in trends and influence factors of different axillary evaluation choices provided basis on surgical precision medicine in DCIS patients. Patients received SLNB increased significantly. The independent influence factors of axillary evaluation were nuclear grade, tumor size and surgical methods. There was no significant differences in prognosis among the groups receiving different axillary evaluations.

[Current practice of implant-based breast reconstruction: results from China national practice questionnaire survey]

Objective: To explore the current clinical practice of implant-based breast reconstruction (IBBR) in China. Methods: The current survey was sponsored by Chinese Anti-Cancer Association, Committee of Breast Cancer Society and Chinese Society of Breast Surgeons. A survey was mailed to 110 hospitals in China, which have more than 200 breast cancer operations performed in 2017. The survey mainly included questions on the clinical practice of IBBR, sociodemographic and geographical factors associated with IBBR practice, reasons and concerns for selecting IBBR, type and timing of breast reconstruction, and the complications of IBBR. Data were analyzed using χ(2) test, Fisher's exact test or Kruskal-Wallis rank sum test. Results: IBBR was available in 86.4% (95/110) included hospitals. It was predominantly performed breast reconstruction surgery, the proportion of IBBR in all the breast reconstruction was 65.75% (4 296/6 534). However, the rate of IBBR in all the patients received mastectomy was only 7.06% (4 296/60 877). Among all the included hospitals, the number of implant reconstructions performed in 2017 was 24 (57.5) cases (M(Q(R)), range: 2-565 cases). Factors associated with the performance of IBBR including regional per capita gross domestic product (H=10.47, P=0.005) and annual surgery volume (H=8.30, P=0.016). The main reasons for choosing IBBR were relatively simple surgical procedure, short learning curve and short operation time. The effects of adjuvant radiotherapy on prosthesis, postoperative complications and patient satisfaction were the main concerns for implant reconstruction. Compared with delay reconstruction, a higher proportion of IBBR was observed in immediate reconstruction (83.1% vs. 62.0%, χ(2)=12.522, P=0.000). In all, 10.5% (10/95) hospitals reported more than 10% grade Ⅲ to Ⅳ capsular contracture. The incidence of infections need surgical intervention was reported between 10% and 20% by 4.2% (4/95) hospitals. Hospitals with 6% to 10% implant rupture and 6% to 15% implant removal were 1.1% (1/95) and 4.2% (4/95) respectively. Conclusions: IBBR was the most common used surgery in breast reconstruction after mastectomy. However, the proportion of IBBR in patients after mastectomy was still low. Reginal economy, surgery volume of hospitals, lack of specialty training program and the concern about complications and patient's satisfaction were the factors affecting the development of IBBR.

[Current trends of breast reconstruction after mastectomy in China: a cross-sectional study]

Objective: To investigate the current trends of breast reconstruction(BR) after mastectomy in China. Methods: A list of hospitals with more than 200 cases of breast cancer surgery per year nationwide was obtained, and 110 institutions were selected according to the geographical distribution. The research was conducted in the form of a questionnaire survey, and 92.3% (169/183) of the questions were single-choice questions. Information such as demographics of surgeons and hospitals, number of mastectomy and BR, type and timing of BR was included in the survey. Survey formal notification letter was issued by the China Anti-Cancer Association Breast Cancer Committee and Chinese College of Surgeons, Committee of Mammary Surgeons. Questionnaires were sent to the respondents of each center by email. The survey time range was from January 1, 2017 to December 31, 2017. All data were completely collected before September 7, 2018. Results: A total of 110 units participated in the survey. In total, 87.3% (96/110) of the hospitals have conducted BR surgery. The BR after mastectomy was 10.7% (6 534/61 099), among this, implant BR accounted for 65.7%(4 296/6 534), autologous BR accounted for 20.1% (1 312/6 534), and autologous combined implant BR accounted for 14.2% (927/6 534). Immediate reconstruction accounted for 67.6% (4 417/6 534) of BR, while delayed BR accounted for 32.4% (2 097/6 534). In 2017, 77.8% (35/45) of the plastic surgery departments cooperated with general surgery departments. General BR could be conducted after mastectomy accounted for 83.6% (92/110). The proportion of reconstruction was positively correlated with the gross domestic product (GDP) per capita (r=0.311, P=0.002). The one-step implant-based BR(IBBR) was the most preferred type in immediate BR. Two-step IBBR was the most preferred method in delayed BR. Hospitals that routinely evaluated aesthetics after BR accounted for 64.6% (62/96), while only 16.7% (16/96) of hospitals used patient-reported outcome measure (PROM). The most commonly used PROM tool was BREAST-Q. Conclusions: The overall BR in China is on upward trend, but gap between China and the developed countries still exists. Breast surgery departments should strengthen further cooperation with plastic surgery departments. Simultaneously, the aesthetics evaluation and PROM after BR should be put a high premium.

[Magnetic resonance imaging findings and differential diagnosis of renal epithelioid angiomyolipoma comparing with renal no-epithelioid angiomyolipoma]

Objective: To investigate whether MRI findings can differentiate renal epithelioid angiomyolipoma (EAML) from renal no-epithelioid (typical) angiomyolipoma. Methods: A total of 44 patients were collected from General Hospital of PLA.These cases were obtained from January 2009 to June 2015.To retrospectively analyze these mainly MRI findings among 12 cases of EAML (age from 27 to 61 years, male 2 cases, female 10 cases, mean age was 46.7 years); 32 cases of renal no-epithelioid AML (age from 34 to 70 years old, male 9 cases, female 23 cases, mean age was 53.4 years old) as case control study. MRI findings included gender, T(2)WI, the signal on gross fat, pseudocapsle, necrosis or cystic degeneration, DWI, hemorrhage and the peak in three phases of dynamic enhancement.All data were analyzed statistically using SPSS version 19.0 (IBM, Armonk, NY, USA). χ(2) test and a single order chart were used to analyze the enumeration data. Results: Comparing with renal no-epithelioid angiomyolipoma, minimal fat, necrosis or cystic degeneration and hemorrhage were statistical significance. P values were 0.002, 0.007, 0.025, respectively.Gender, solid components of tumors on T(2)WI, the signal of DWI, pesudocapsule and the peak of enhancement had no statistical significance. P values were 0.863, 0.053, 0.479, 0.460, respectively. Conclusion: Comparing with renal no-epithelioid AML, necrosis or cystic degeneration and hemorrhage with minimal fat are characteristic MRI findings of EAML.

Abstract P5-16-08: Applications of rib sparing technique in internal mammary vessels exposure of abdominal free flap breast reconstructions

Background:

Internal mammary vessels (IMVs) are widely used recipient vessels in abdominal free flaps breast reconstructions. Exposure of IMVs usually needs to resect a segment of costal cartilage or rib during the operations. The rib sparing technique is an alternative method with less damage. This study aims to analysis the applicability and advantages of rib sparing technique of IMVs exposure in breast reconstruction.

Methods:

medical records of 215 patients who underwent abdominal free flap reconstruction from November 2006 to December 2017 were analyzed. The factors influencing the choice of vessels and rib sparing were analyzed. The outcomes of rib sparing were assessed. Intercostal space (ICS) width and other related data were measured by the preoperative thin slice chest computed tomography (CT) scan images.

Results:

Among all 215 patients with 218 flaps, 172 flaps used IMVs as the recipient vessels while 13 used thoracodorsalvessels and 33 used subscapular vessels. The proportion of IMVs as recipient vessels showed a rising trend in general and remained over 90% for the last three years in our center. Patients with immediate reconstruction (p=0.005) and axillary lymph nodes dissection(ALND) (p&lt;0.001) were less likely to use IMVs, both in univariate and multivariate logistic regression analysis. Patients' BMI and radiotherapy history showed no statistically significant differences between the IMVs group and the other vessels group (p=0.338 and 0.811). The rib sparing rate in IMVs exposure increased yearly and exceeded 40% in 2013, now it maintained more than 60% during the recent 3 years. Additionally, among the patients who received rib sparing IMVs exposure in 2017, the mean ICS width was relatively smaller than that in 2013 (2.54cm V.S 2.93cm, p=0.124). Compared with rib resection group, patients with rib sparing were higher (163.57 ± 4.44 cm vs. 161.83 ± 4.30 cm, p=0.047) and with a wider ICS (2.65 ± 0.54 cm vs. 2.25± 0.38 cm, p&lt;0.01), while the depth from the surface of the pectoralis major muscle to the IMVs and distance between the parasternal line and IMVs had no difference between the two groups. Rib sparing group has a shorter surgery and hospitalization time, as well as a lower severe complication rate, but the differences were not statistically significant (p= 0.120, 0.450 and 0.296).

Conclusion:

IMVs were used more frequently as the recipient vessels in abdominal free flap breast reconstructions, especially when axillary operation was not carried out at the same time. Rib sparing technique had the potential to decrease surgery time and hospitalization days, as well as the severe complications rate. It could be used in most of patients received free flap reconstruction when IMVs were used, particularly in higher patients and patients with a wider ICS. Preoperative slice chest CT scan can be used to measure the ICS width to provide suggestions for dealing with the ribs.

Citation Format: Zhang Q, Xiao Q, Guo R, Wu J, Gu Y, Xiu B. Applications of rib sparing technique in internal mammary vessels exposure of abdominal free flap breast reconstructions [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 P5-16-08.

Abstract P6-05-01: A novel cleaved cytoplasmic lncRNA LacRNA interacts with PHB2 and suppresses breast cancer metastasis via repressing MYC targets

Long noncoding RNAs (lncRNAs) have been implicated in breast cancer metastases through largely unknown mechanisms. In this study, we used microarray analysis to compare lncRNAs expression levels between matched pairs of breast lymph node metastatic tissues and primary tumors. We discovered that lncRNA LINC00478 was substantially downregulated in the metastatic tumor samples. Interestingly, we found that LINC00478 could be cleaved by RNase to simultaneously generates the mature 5' ends of cytoplasmic RNA and 3' ends of nuclear RNA by polyadenylation. We named 5' ends 791-nt RNA as LacRNA (LINC00478-assciated cytoplasmic RNA). Over expression of full-length LINC00478 and LacRNA, but not LINC00478 3' RNA, significantly inhibited breast cancer proliferation, invasion and metastasis in vitro and in vivo.We used CRISPR-dCas9 complex to mediate efficient transcriptional activation of LacRNA at endogenous genomic loci followed by RNA-seq analyses. Gene set enrichment analysis (GSEA) showed that the MYC pathway/targets were prominent gene sets negatively enriched in LacRNA-activated cells. Further study revealed that LacRNA exerted its tumor suppressive activity by directly binding with prohibitin2(PHB2) to enhance its protein stability, which promoted PHB2 competing with MYC for transcriptionally suppressing the MYC target genes (e.g., CDC20, CDC45, CCNA2 and MAD2L1). Mechanistically, LacRNA inhibits breast cancer invasion and metastasis by interacting with PHB2 through LacRNA's 1-300nt region. In addition, taking advantage of CRISPR system to knock-out and activate the expression of LacRNA, as well as rescue experiment, we uncovered the positive correlation between LacRNA and PHB2 and their role in suppressing MYC target genes and cancer metastasis. At the same time, LacRNA can attenuated the MYC induced activation of MYC targets through binding with PHB2, indicating that LacRNA plays a central role in the suppression of MYC target genes. We further explored the role of LacRNA in inhibiting lung metastasis by implanting LacRNA-activated LM2 cells into the mammary fat pads of NOD-SCID mice. Luciferase imaging and histological analysis were used to detect lung metastasis and found that LacRNA significantly suppressed lung metastasis. Immunohistochemistry were used to detect the expression of PHB2 and MYC targets in both orthotopic tumors and lung metastasis and verified their correlation in vivo. Extensive analyses of clinical data indicated that LacRNA level was substantially downregulated in metastases tumors accompanied by enrichment of MYC targets. The robustness value of LacRNA expression was further verified in two independent patient cohorts, including 530 invasive breast cancer tumors in Fudan University Shanghai Cancer Center (FUSCC) and 819 breast patients' data from TCGA. High LacRNA expression level had a significantly better clinical outcome in both cohorts and represented an independent prognostic predictor for DFS (HR=0.48, P=0.006, multivariate analysis) and OS (HR=0.32, P=0.009, multivariate analysis) in FUSCC cohort. Collectively, LacRNA functions as a tumor suppressor lncRNA that inhibits breast cancer invasion-metastasis cascade.

Citation Format: Guo R, Su Y-H, Xue J-y, Si J, Chi Y-y, Wu J. A novel cleaved cytoplasmic lncRNA LacRNA interacts with PHB2 and suppresses breast cancer metastasis via repressing MYC targets [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 P6-05-01.