Impact of Cardiac Pacemaker Implantation in Patients With Acute Traumatic Cervical Spinal Cord Injury

BACKGROUND

Cardiac pacemaker implantation may be indicated in patients with refractory bradycardia following a cervical spinal cord injury (CSCI). However, evidence about the impact of this procedure on outcomes is lacking. We planned a study to assess whether the implantation of a pacemaker would decrease mortality and hospital resource utilization in patients with CSCI.

METHODS

Adult patients with CSCI in the Trauma Quality Improvement Program (TQIP) database between 2016 and 2019 were retrospectively analyzed. Patients were divided into "pacemaker" and "non-pacemaker" groups, and their baseline characteristics and clinical outcomes were analyzed.

RESULTS

A total of 6774 cases were analyzed. The pacemaker group showed higher in-hospital rates of cardiac arrest, myocardial infarction, and longer duration of mechanical ventilation and ICU stay than the non-pacemaker group. Nevertheless, pacemaker placement was associated with a significant decrease in mortality (4.2% vs 26.0%, P < .01).

CONCLUSIONS

Patients with CSCI requiring a pacemaker placement had better survival than those treated without a pacemaker. Pacemaker implantation should be highly considered in patients who develop refractory bradycardia after CSCI.

Procedure Risk vs Frailty in Outcomes for Elderly Emergency General Surgery Patients: Results of a National Analysis

BACKGROUND

The direct association between procedure risk and outcomes in elderly emergency general surgery (EGS) patients has not been analyzed. Studies only highlight the importance of frailty. A comprehensive analysis of relevant risk factors and their association with outcomes in elderly EGS patients is lacking. We hypothesized that procedure risk has a stronger association with relevant outcomes in elderly EGS patients compared to frailty.

STUDY DESIGN

Elderly patients (age > 65) undergoing emergency general surgery operative procedures were identified in the NSQIP) database (2018 to 2020) and stratified based on the presence of frailty calculated by the Modified 5 Item Frailty Index (mFI-5; mFI 0 Non-Frail, mFI 1-2 Frail, and mFI ≥3 Severely Frail) and based on procedure risk. Multivariable regression models and Receiving Operative Curve (ROC) analysis were used to determine risk factors associated with outcomes.

RESULTS

A total of 59,633 elderly EGS patients were classified into non-frail (17,496; 29.3%), frail (39,588; 66.4%), and severely frail (2,549; 4.3%). There were 25,157 patients in the low-risk procedure group and 34,476 in the high-risk group.Frailty and procedure risk were associated with increased mortality, complications, failure to rescue, and readmissions. Differences in outcomes were greater when patients were stratified according to procedure risk compared to frailty stratification alone. Procedure risk had a stronger association with relevant outcomes in elderly EGS patients compared to frailty.

CONCLUSIONS

Assessing frailty in the elderly EGS patient population without adjusting for the type of procedure or procedure risk ultimately presents an incomplete representation of how frailty impacts patient-related outcomes.

Deaths After Readmissions are Mostly Attributable to Failure-to-Rescue in EGS Patients

INTRODUCTION

We have recently shown that readmission after EGS procedures carries a 4-fold higher mortality rate when compared to those not readmitted. Understanding factors associated with death after readmission is paramount to improving outcomes for EGS patients. We aimed to identify risk factors contributing to failure-to-rescue (FTR) during readmission after EGS. We hypothesized that most post-readmission deaths in EGS are attributable to FTR.

METHODS

A retrospective cohort study using the NSQIP database 2013-2019 was performed. Patients who underwent 1 of 9 urgent/emergent surgical procedures representing 80% of EGS burden of disease, who were readmitted within 30 days post-procedure were identified. The procedures were classified as low- and high-risk. Patient characteristics analyzed included age, sex, BMI, ASA score comorbidities, postoperative complications, frailty, and FTR. The population was assessed for risk factors associated with mortality and FTR by uni- and multivariate logistic regression.

RESULTS

Of 312,862 EGS cases, 16,306 required readmission. Of those, 10,748 (3.4%) developed a postoperative complication. Overall mortality after readmission was 2.4%, with 90.6% of deaths attributable to FTR. Frailty, high-risk procedures, pulmonary complications, AKI, sepsis, and the need for reoperation increased the risk of FTR.

DISCUSSION

Death after a complication is common in EGS readmissions. The impact of FTR could be minimized with the implementation of measures to allow early identification and intervention or prevention of infectious, respiratory, and renal complications.

Impact of traditional versus nontraditional initiation dosing schedule of paliperidone palmitate on 30-day readmission and safety

Introduction

Paliperidone palmitate (PP), a second-generation long-acting injectable antipsychotic, requires 2 injections upon initiation. Due to the fast-paced nature of the inpatient setting, the second dose may be administered earlier than recommended by labeled use despite the lack of evidence that evaluates this practice.

Methods

This was a retrospective chart review that investigated the outcomes associated with the timing of the second PP initiation dose with the aim of comparing patients who received the second PP dose fewer than 3 days after the first injection with those who received it between 3 and 11 days after the first injection. The primary outcomes included 30-day psychiatric readmission, index hospitalization length of stay, and time until the next psychiatric hospitalization. Secondary outcomes included 6-month readmission and the percentage of patients who experienced an adverse event after the second injection.

Results

No statistically significant differences were observed between groups for 30-day readmission. There was a statistically significant shortened index length of hospitalization (median, 2 vs 4 days; P < 0.001) and a non-statistically significant trend for time until the next psychiatric hospitalization (median, 25 vs 47 days) when comparing those who received the nontraditional loading regimen to those who received the traditional labeled loading regimen. No differences were observed in the secondary outcomes or safety/tolerability.

Discussion

The results of the study indicate that there are no significant differences in readmission rates and adverse drug reactions in those who received the second PP dose earlier than recommended per labeled use. Larger, controlled studies are needed to further investigate clinical and safety outcomes.

Open Versus Percutaneous Tracheostomy in Patients With Liver Cirrhosis: Analysis of a Nationwide Database

BACKGROUND

Evidence for the appropriate type of tracheostomy in patients with liver cirrhosis is lacking. A retrospective analysis of the National Inpatient Sample (NIS) was performed.

METHODS

Adult patients with liver cirrhosis undergoing tracheostomy while on mechanical ventilation for respiratory failure were abstracted from the NIS database between 2016 and 2018 and analyzed. Patients were divided according to the type of tracheostomy performed into open tracheostomy (OT) and percutaneous tracheostomy (PT) and analyzed for tracheostomy complications and clinical outcomes. Subgroup analyses were performed for patients with compensated cirrhosis (CC) and decompensated cirrhosis (DC).

RESULTS

A total of 44745 cases were analyzed. The OT group had a higher rate of overall tracheostomy-related complications (TC) (5.1% vs 3.5%; P < .001), hemorrhage from the tracheostomy site (HC) (2.7% vs 1.8%; P = .008) and other complications (OC) (2.7% vs 1.8%, P = .003). Multivariate analyses showed that OT was a risk factor for TC (Adjusted odds ratio (AOR) 1.50, P < .001), HC (AOR 1.46, P = .009), and OC (AOR 1.55, P = .003). Similarly, in subgroup analyses, OT cases, compared to PT, were associated with increased TC (5.0% vs 3.4%, P < .001), HC (2.7% vs 1.7%, P = .002) and OC (2.6% vs 1.8%, P = .020) in DC patients.

DISCUSSION

OT is associated with a significantly higher rate of complications. OT was also associated with more complications in DC patients, suggesting that a percutaneous approach may be the best option in cirrhotic patients when feasible.

PSAT035 COVID-19 Infection Increases DKA and mortality- A Harbinger for Increased Acute Diabetes Emergencies in the Future?

DM patients infected with COVID-19 are at risk for developing severe complications including DKA and/or HHS, with a more severe disease course and higher mortality compared to those without DM or hyperglycemia. As COVID-19 is evolving into an endemic risk for the population, it is important to determine patients at risk for COVID-19 complications and outcomes. The Riverside University Health System Medical Center (RUHS-MC)-DKA Outcomes Group (RUDOG) initiated a study to characterize patients admitted for fatal DKA and/or HHS before and during the pandemic.

This was a retrospective cohort study reviewing medical records of non-pregnant adults age 18 or older admitted to the RUHS-MC for DKA and/or HHS from Mar 2020 to Feb 2021 ("pandemic") compared to the 3 preceding years ("pre-pandemic"). The descriptive statistics were used to determine the clinical characteristics of hospitalized adult patients with DKA and/or HHS. Information of patient characteristics was extracted from chart reviews. Categorical data were compared using Fisher's Exact Test. Numerical variables were assessed using Mann-Whitney Test.

The mortality rate during the pandemic was 8.4% (30/335) versus 1.7% (5/285) in the pre-pandemic period. Most of the deaths (24/30) were COVID infected. On average, the cases of deaths during pandemic had DM for a longer duration. There was no difference regarding age, race, HgbA1c on admission, insulin use history, and rate of micro- or macrovascular complications comparing these periods. More patients had HTN (80%) and HF (23%) during pandemic compared to pre-pandemic (69.2% and 7.7%, respectively). Infection was the cause of death for 63% and 31% of patients admitted for DKA and/or HHS during the pandemic versus pre-pandemic.

There is a clear global concern that COVID-19 will be an endemic infectious disease placing people with pre-existing conditions such as DM at increased risk for morbidities and death. Our study has clearly demonstrated that contracting COVID is a risk for increased incidence of DKA and/or HHS and mortality compared to pre-pandemic levels. In addition, we have shown that certain pre-existing comorbidities are associated with the mortality of DKA and/or HHS including HTN and HF with COVID infection. The duration of DM was longer among patients that died during pandemic, regardless of age, race, or HgbA1c on admission. This finding is intriguing as we did not see increased DKA and/or HHS based on the number of micro- or macrovascular complications suggesting duration alone may be a new risk determinant.

Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m.

The unequal impact of interhospital transfers on emergency general surgery patients: Procedure risk and time to surgery matter

BACKGROUND

The impact of interhospital transfer on outcomes of patients undergoing emergency general surgery (EGS) procedures is incompletely studied. We set out to determine if transfer before definitive surgical care leads to worse outcomes in EGS patients.

METHODS

Using the National Surgical Quality Improvement Project database (2013-2019), a retrospective cohort study was conducted including nine surgical procedures encompassing 80% of the burden of EGS diseases, performed on an urgent/emergent basis. The procedures were classified as low risk (open and laparoscopic appendectomy and laparoscopic cholecystectomy) and high risk (open cholecystectomy, laparoscopic and open colectomy, lysis of adhesions, perforated ulcer repair, small bowel resection, and exploratory laparotomy). Time to surgery was recorded in days. The impact of interhospital transfer on outcomes (mortality, major complications, 30-day reoperations, and 30-day readmissions) and length of stay, according to procedure risk and time to surgery, were analyzed by multivariate logistic regression and inverse probability treatment of the weighting with treatment effect in the treated.

RESULTS

A total of 329,613 patients were included in the study (284,783 direct admission and 44,830 transfers). Adjusted mortality (3.1% vs. 10.4%; adjusted odds ratio [AOR], 1.28; p < 0.001), major complications (6.7% vs. 18.9%; AOR, 1.39; p < 0.001), 30-day reoperations (3.1% vs. 6.4%; AOR, 1.22; p < 0.001), and length of stay (2 vs. 5) were higher in transferred patients. Transfer had no effect on 30-day readmissions (6% vs. 8.5%; AOR, 1.04; p = 0.063). These results were also observed in high-risk surgery patients and in the late surgery group. The results were further confirmed after robust propensity score weighting was performed.

CONCLUSION

We have demonstrated that delays to surgical intervention affect outcomes and that interhospital transfer of EGS patients for definitive surgical care has a negative impact on mortality, development of postoperative complications, and reoperations in patients undergoing high-risk EGS procedures. These findings may have important implications for regionalization of EGS care.

LEVEL OF EVIDENCE

Prognostic/epidemiological, level III.

A Nationwide Study of Intimate Partner Violence

BACKGROUND

Intimate partner violence (IPV) refers to physical or sexual violence, stalking, and psychological aggression by an intimate partner. The present study aims to examine the incidence, injury patterns, and outcomes using a representative nationwide data set.

STUDY DESIGN

The Nationwide Emergency Department Sample database was queried from 2010 to 2014 to identify IPV in adult patients by injury code E967.3. Demographics, diagnoses, and injury mechanisms were captured. Primary outcome was mortality, and logistic regression analyses were used to compare the baselines and outcomes.

RESULTS

132 806 IPV emergency visits were identified, with 5.1% of patients requiring hospitalization. Most patients were female (92.6%). The most common injury mechanisms were unintentional injury (36%) and striking (22.0%). Contusions of face/scalp/neck (13.2%) and unspecified head injury (6.9%) were the most common diagnoses. Males were significantly older [median and interquartile range of 39 (30, 50)] than females [33 (26, 43)], and were more frequently hospitalized (6.7% vs. 5.0%, P = .002) with more injuries with injury severity score ≥ 15 (.7% vs. .4%, P = .004) than females. Overall, IPV-related mortality was .06%, .26% in males and .05% in females (P = .003). Older age (odds ratio (OR) = 1.053) and male gender (OR = 3.102) were significantly associated with mortality. The annual incidence rate decreased from 9.7 in 2010 to 8.2/100 000 US population in 2014 (R² = .659).

CONCLUSIONS

Young women are more likely to be victims of IPV, whereas men are more likely to be older and hospitalized with more severe injuries and worse outcomes.

Endovascular repair is a feasible option for superficial femoral artery injuries: a comparative effectiveness analysis

PURPOSE

To compare outcomes between open (OR) and endovascular repair following superficial femoral artery (SFA) injuries.

METHODS

This is a cross-sectional study querying the 2012-2014 National Inpatient Sample for SFA injuries. Patients were grouped into OR and stent-graft placement (SGP). Primary outcome was in-hospital mortality. Secondary outcomes included hospital length of stay (HLOS), fasciotomy and amputation rate, and cost. Wilcoxon rank-sum, Kruskal-Wallis, Chi-squared test with Bonferroni adjustment were used as appropriate; p < 0.05 was significant.

RESULTS

255 Patients were identified. Mean age was 34.6 years and majority were males. OR was performed in 82.7%. Overall mortality rate was 3.7%. Median HLOS was 8 days. Fasciotomies were performed in 31% and lower limb amputations in 3.7%. Males more often underwent OR (89.0% vs. 73.1%, p < 0.01). SGP patients were significantly older (44.9 vs. 32.5 years; p < 0.01), and with Medicare insurance (20.5% vs. 6.5%; p < 0.01. Mortality, HLOS, and hospitalization cost were not significantly different. OR patients had higher rate of fasciotomy (35.4% vs. 15.4%; p < 0.01).

CONCLUSIONS

Endovascular management is not inferior to OR following SFA injuries and both carry a low amputation rate. OR is associated with a higher fasciotomy rate. Endovascular repair should be considered when technically feasible.

Severe Pelvic Fracture in the Elderly: High Morbidity, Mortality, and Resource Utilization

Severe pelvic fractures (PF) in the elderly are common and analysis of outcomes and resource utilization are lacking. Using the National Trauma Databank (2007-2016), 13 267 patients aged ≥65 years with severe PF (Abbreviated Injury Scale [AIS] pelvis ≥3; AIS 3 = 10 388; AIS 4 = 2124; AIS 5 = 805) were studied. Demographic data, management, resource utilization, complications, and mortality were analyzed for each group. Data are represented as % or median interquartile range (IQR). Multivariate logistic regression analyzed risk factors for mortality, Intensive Care Unit (ICU) admission, and ventilator use. Median age was 77, and most of them were females (59%). Falls occurred in 52%, motor vechicle crash in 21.5%, and pedestrian struck in 11.6%. Median injury severity score was 16 (IQR: 9,27). Shock on admission (9.4%) increased with injury severity. Glasgow Coma Scale < 8 occurred in 8%. Blood transfusion increased with injury severity (17%, 29%, and 51%). Angiography occurred in 9%, external fixation in 4%, internal fixation in 16%, and pelvic packing in 1%, the majority in the AIS 5 group. Overall, 46% required ICU admission and 30% underwent mechanical ventilation; median Hospital Length of Stay was 6 (IQR 4,11), ICU length of stay was 5 (IQR 2,10), and median ventilator days were 4 (IQR 1-11). Mortality rate was 13.3% (AIS 3 = 10%, AIS 4 = 19%, and AIS 5 = 44%).Severe PF in the elderly is associated with high resource utilization, complications, and mortality.

Lights off, camera on! Laparoscopic cholecystectomy improves outcomes in cirrhotic patients with acute cholecystitis

BACKGROUND

The best surgical approach to treat acute cholecystitis (AC) in cirrhotic patients is controversial. This study aimed to evaluate treatment options in cirrhotic patients with AC. We hypothesized that laparoscopic cholecystectomy (LC) would lead to better clinical outcomes when compared to non-operative management (NOM) and open cholecystectomy (OC), independent of the severity of liver cirrhosis.

METHODS

Patients from the National Inpatient Sample diagnosed with AC were stratified into no cirrhosis (NC), compensated cirrhosis (CC), and decompensated cirrhosis (DC) and analyzed according to treatment: NOM, OC, and LC. Primary outcome was in-hospital mortality. Secondary outcomes included hospital length of stay (HLOS), cost, and surgical complications. Univariate and multivariate analyses using generalized linear models were performed. A P < 0.05 was deemed significant.

RESULTS

Of 1 367 495 AC patients, 49 030 (3.6%) had cirrhosis; 23 260 had CC, and 25 770 had DC. LC (12 080 in CC group and 4840 in DC group) was accompanied by significantly lower mortality, HLOS, complications, and cost when compared to OC and NOM. OC was significantly associated with higher mortality, increased HLOS, total cost, and postoperative complications, independent of the presence or severity of cirrhosis.

CONCLUSIONS

LC in cirrhotic patients leads to superior outcomes compared to OC and NOM regardless of the severity of cirrhosis.

The effect of age and sex on outcomes following isolated moderate to severe traumatic brain injury

PURPOSE

The impact of female sex on traumatic brain injury (TBI) outcomes remains controversial. The combined impact of age and sex on TBI outcomes must be clarified. We hypothesized that females have better outcomes than males in the premenopausal age group.

METHODS

Data from the 2007-2016 National Trauma Data Bank of the Committee on Trauma-American College of Surgeons were used. Of a total of 686,549 patients with moderate to severe TBI (AIS ≥ 3), 251,491 were female. Comparison analyses of clinical characteristics and outcomes between females and males were conducted at different age groups: < 45 years, 45-55, and > 55 years. Logistic regressions were performed to assess the impact of age and female sex on mortality and complications.

RESULTS

Mortality rate between females and males aged < 45 and 45-55 years was similar, but significantly reduced in the > 55 years group. After multivariate logistic regression analysis controlling for multiple confounding factors, we found that females aged > 55 years had markedly decreased risk of mortality (AOR: 0.857, 95% CI 0.835-0.879, p < 0.001) and complications.

CONCLUSION

Female patients in the postmenopausal stage have better outcomes following TBI than males, but pre- and perimenopausal females do not, suggesting that female sexual hormones may not provide a significant protective effect on clinical outcomes following isolated moderate to severe TBI.

Acute Colonic Diverticulitis and Cirrhosis: Outcomes of Laparoscopic Colectomy Compared with an Open Approach

BACKGROUND

The impact of cirrhosis on outcomes of acute colonic diverticulitis (ACD) has been studied infrequently. We investigated the effect of cirrhosis on outcomes of surgical patients with ACD treated by either an open or laparoscopic approach.

METHODS

A cross-sectional study was performed using the Nationwide Inpatient Sample 2012 to 2014. Patients with ACD were stratified into compensated and decompensated cirrhosis for comparisons of demographic characteristics, hospital length of stay, complications, mortality, and cost. Groups were stratified according to surgical treatment: open colectomy and laparoscopic colectomy. A comparative effectiveness analysis of outcomes was performed between the 2 surgical treatments. Univariate comparisons between groups and multivariate regression analysis were performed to identify risk factors for mortality and specific complications.

RESULTS

Of 1,172,875 patients hospitalized with the diagnosis of ACD during the study period, 1,145 were cirrhotic. The majority were male (59%). There were 660 compensated cirrhotic patients and 485 decompensated cirrhotic patients and all underwent either open (n = 875) or laparoscopic colectomy (n = 270). Consistently, marked increases in mortality, hospital length of stay, and cost were observed in decompensated cirrhotic patients regardless of the type of treatment. Laparoscopic colectomy was accompanied by shorter hospital length of stay, lower costs, and significantly decreased mortality rate compared with open colectomy in compensated and decompensated cirrhotic patients.

CONCLUSIONS

The presence of cirrhosis markedly impacts outcomes in patients with ACD, leading to prolonged hospitalization, higher cost, and increased complications and deaths. Laparoscopic colectomy is associated with better outcomes in patients requiring surgical management, including those with decompensated cirrhosis.

Abstract 2146: RASSF1C modulation of Piwi-interacting RNAs (piRNAs) in lung cancer

Introduction: RASSF1C is emerging as an important oncoprotein in lung cancer cell growth. We have shown that RASSF1C promotes lung cancer cell proliferation and migration; and RASSF1C up-regulates important genes in lung cancer cell growth that include a stem cell self-renewal gene, piwi1 (hiwi). PIWI-like proteins are a subfamily of Argonaute proteins that interact with small PIWI-interacting RNA molecules (known as piRNAs that are 24-32 nucleotides long) to form complexes that regulate transcriptional and translational repression. This leads to inhibition of apoptosis, stimulation of cell division and proliferation, and down-regulation of cyclin inhibitors and tumor suppressors. Therefore, modulation of Piwil1-piRNA gene expression by RASSF1C suggests a potential role for RASSF1C in lung cancer stem cell development and progression. To further investigate our hypothesis, we carried out a global piRNA microarray screen to identify piRNAs that are modulated by RASSF1C in lung cancer cells.

Method: A piRNA microarray screen was performed using the lung cancer cell line H1299 stably over-expressing RASSF1C (and controls). Total RNA was extracted from experimental and control cells and was submitted to Arraystar (Rockville, MD) for the piRNA microarray screen and data analysis.

Results: The piRNA microarray screen identified several piRNAs that are regulated by RASSF1C and we have confirmed the expression of some of them in cell lines. The function of the piRNAs identified is yet to be determined. We have initiated studies to determine the function of some of the most up-regulated and down-regulated piRNA genes in lung cancer cells. We are also profiling the expression of these piRNAs in normal and lung tumor tissues.

Conclusion: Several piRNAs are target genes of RASSF1C. Characterization of the function of these piRNAs may enhance our understanding of the role of RASSF1C in promoting lung cancer stem cell growth and progression. Linking a Rassf1c-Piwil1/piRNAs axis to lung cancer stem cell development and progression could possibly lead to discovery of new diagnostic and therapeutic targets for lung cancer.

Citation Format: Yousef G. Amaar, Matthew Firek, Mark E. Reeves, Mark E. Reeves. RASSF1C modulation of Piwi-interacting RNAs (piRNAs) in lung cancer. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2146. doi:10.1158/1538-7445.AM2015-2146

Abstract 2454: Ampk and hdac pathways and regulation rassf1c gene expression

Introduction: We have previously shown that RASSF1C promotes cell proliferation, migration and attenuates apoptosis in cancer cells. We have also shown that RASSF1C is significantly up-regulated in breast and lung cancer tissues compared to normal tissues. Together these demonstrate that RASSF1C, is not a tumor suppressor like RASSF1A, but instead appears to function as an oncoprotein.

Currently nothing is known about the upstream signaling cascades involved in regulating RASSF1C gene expression and thus we performed transcriptome PCR array study to identify chemicals inhibitors that modulate(s) RASSF1C expression.

Method: A transcriptome PCR array was obtained from Qiagen. It consisted of cDNA from breast cancer cell line MCF7 cells treated with 90 different chemical inhibitors that regulate various signaling pathways. The array was screened with RASSF1C gene specific primers. Data analysis was performed by importing the Ct values obtained into data analysis software.

Results: The PCR array screen identified several chemical reagents that appear to up-regulate and several that seem to down-regulate RASSF1C expression by ≥ 1.5 fold. The two most notable reagents are Dorsopmorhin (AMPK inhibitor) which up-regulates RASSF1C expression by 2.8 fold and Trichostatin A (HDAC inhibitor) which down regulates RASSF1C expression by 2 fold. We are in process of confirming the effect of these inhibitors in a panel of breast and lung cancer cells.

Conclusion: The findings are novel and suggest that inhibition of AMPK pathway induces RASSF1C expression while inhibition of HDAC pathway suppresses RASSF1C gene expression. We should note that Trichostatin A has been shown to activate AMPK, inhibits HDAC, arrests cell growth, and induces apoptosis in human cancers. Our findings provide a potential mechanism for regulating RASSF1C gene expression through the modulation of AMPK and HDAC pathways.

Citation Format: Yousef G. Amaar, Mark E. Reeves, Matthew Firek. Ampk and hdac pathways and regulation rassf1c gene expression. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 2454. doi:10.1158/1538-7445.AM2014-2454

Evidence that RASSF1C stimulation of lung cancer cell proliferation depends on IGFBP-5 and PIWIL1 expression levels

RASSF1C is a major isoform of the RASSF1 gene, and is emerging as an oncogene. This is in contradistinction to the RASSF1A isoform, which is an established tumor suppressor. We have previously shown that RASSF1C promotes lung cancer cell proliferation and have identified RASSF1C target genes with growth promoting functions. Here, we further report that RASSF1C promotes lung cancer cell migration and enhances lung cancer cell tumor sphere formation. We also show that RASSF1C over-expression reduces the inhibitory effects of the anti-cancer agent, betulinic acid (BA), on lung cancer cell proliferation. In previous work, we demonstrated that RASSF1C up-regulates piwil1 gene expression, which is a stem cell self-renewal gene that is over-expressed in several human cancers, including lung cancer. Here, we report on the effects of BA on piwil1 gene expression. Cells treated with BA show decreased piwil1 expression. Also, interaction of IGFBP-5 with RASSF1C appears to prevent RASSF1C from up-regulating PIWIL1 protein levels. These findings suggest that IGFBP-5 may be a negative modulator of RASSF1C/ PIWIL1 growth-promoting activities. In addition, we found that inhibition of the ATM-AMPK pathway up-regulates RASSF1C gene expression.

Abstract 4288: RASSF1C, unlike RASSF1A, reduces TNF-α induced phosphorylation of MST1/2

Introduction: Recently, RASSF1A has been shown to mediate the apoptotic effects of TNF-α by interacting with the mammalian sterile 20-like kinase 1 and 2 (MST1/2) through the Salvador/Rassf/Hippo (SARAH) domain leading to MST1/2 phosphorylation activation of apoptosis through the Hippo pathway. In contrast, we have previously shown that RASSF1C promotes cell proliferation and attenuates apoptosis in cancer cells. Since both RASSF1A and RASSF1C contain the SARAH domain located in their identical C-termini, RASSF1C should be capable of interacting with SARAH domain-containing proteins, and could potentially attenuate MST1/2-mediated apoptosis through the Hippo pathway. Thus, in this study we have investigated the impact of RASSF1C on MST1/2 activation/phosphorylation in presence of TNF-α, including whether RASSF1C modulates MST1/2 pro-apoptotic effects through the Hippo pathway differently from RASSF1A.

Method: Breast and lung cancer cells over-expressing RASSF1A and RASSF1C were used in this study. Cells were cultured in the proper media and treated with TNF-α for 12-18 hr. Cells were collected and used for Western blot analysis utilizing antibodies that detect MST and p-MST antibodies.

Results: Our preliminary data suggest that RASSF1C over-expression decreases the phosphorylation levels of MST1/2 in TNF-α-treated breast and lung cancer cells compared to those cells over-expressing RASSF1A

Conclusion: Our findings suggest that over-expression of RASSF1C in breast and lung cancer cells may attenuate the MST1/2 apoptotic effects by sequestering of MST1/2 proteins and inhibiting their activation by phosphorylation. The findings also further support our hypothesis that RASSF1C attenuates apoptosis; and RASSF1C, unlike RASSF1A, may inhibit MST1/2 activation and hence may negatively modulate the Hippo pathway.

Citation Format: Yousef G. Amaar, Matthew Firek, Mark E. Reeves. RASSF1C, unlike RASSF1A, reduces TNF-α induced phosphorylation of MST1/2. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 4288. doi:10.1158/1538-7445.AM2013-4288