Preclinical Models of Anal Cancer Combined-Modality Therapy

INTRODUCTION

There have been no significant changes in anal cancer treatment options in 4 decades. In this study, we highlight two preclinical models designed to assess anal cancer treatments.

MATERIALS AND METHODS

Transgenic K14E6/E7 mice were treated with 7, 12-dimethylbenz(a)anthracene until anal tumors developed. Mice were treated with localized radiation in addition to chemotherapy (combined-modality therapy [CMT]) and compared to no treatment control (NTC). K14E6/E7 mouse anal spheroids with and without Pik3ca mutations were isolated and treated with vehicle, LY3023414 (LY3) (a drug previously shown to be effective in cancer prevention), CMT, or CMT + LY3.

RESULTS

In the in vivo model, there was a significant increase in survival in the CMT group compared to the NTC group (P = 0.0392). In the ex vivo model, there was a significant decrease in the mean diameter of CMT and CMT + LY3-treated spheroids compared to vehicle (P ≤ 0.0001). For LY3 alone compared to vehicle, there was a statistically significant decrease in spheroid size in the K14E6/E7 group without mutation (P = 0.0004).

CONCLUSIONS

We have provided proof of concept for two preclinical anal cancer treatment models that allow for the future testing of novel therapies for anal cancer.

A phase I study of intra-anal artesunate (suppositories) to treat anal high-grade squamous intraepithelial lesions

BACKGROUND

Ablation or surgical excision is the typical treatment of anal high-grade squamous intraepithelial lesions (HSIL). Recurrences are common due to the persistence of underlying human papillomavirus (HPV) infection. Additional well-tolerated and effective non-surgical options for HPV-associated anal disease are needed.

METHODS

This 3+3 dose escalation Phase I clinical trial evaluated the safety and tolerability of artesunate suppositories in the treatment of patients with biopsy-proven HSIL.

RESULTS

The maximal tolerated dose was 400 mg, administered in 3 cycles. All adverse events associated with the use 200- and 400-mg artesunate suppositories were Grade 1. At the 600-mg dose, patients experienced clinically significant nausea.

CONCLUSION

Artesunate suppositories are a safe treatment option for anal HSIL.

Emerging Prognostic and Predictive Significance of Stress Keratin 17 in HPV-Associated and Non HPV-Associated Human Cancers: A Scoping Review

A growing body of literature suggests that the expression of cytokeratin 17 (K17) correlates with inferior clinical outcomes across various cancer types. In this scoping review, we aimed to review and map the available clinical evidence of the prognostic and predictive value of K17 in human cancers. PubMed, Web of Science, Embase (via Scopus), Cochrane Central Register of Controlled Trials, and Google Scholar were searched for studies of K17 expression in human cancers. Eligible studies were peer-reviewed, published in English, presented original data, and directly evaluated the association between K17 and clinical outcomes in human cancers. Of the 1705 studies identified in our search, 58 studies met criteria for inclusion. Studies assessed the prognostic significance (n = 54), predictive significance (n = 2), or both the prognostic and predictive significance (n = 2). Altogether, 11 studies (19.0%) investigated the clinical relevance of K17 in cancers with a known etiologic association to HPV; of those, 8 (13.8%) were focused on head and neck squamous cell carcinoma (HNSCC), and 3 (5.1%) were focused on cervical squamous cell carcinoma (SCC). To date, HNSCC, as well as triple-negative breast cancer (TNBC) and pancreatic cancer, were the most frequently studied cancer types. K17 had prognostic significance in 16/17 investigated cancer types and 43/56 studies. Our analysis suggests that K17 is a negative prognostic factor in the majority of studied cancer types, including HPV-associated types such as HNSCC and cervical cancer (13/17), and a positive prognostic factor in 2/17 studied cancer types (urothelial carcinoma of the upper urinary tract and breast cancer). In three out of four predictive studies, K17 was a negative predictive factor for chemotherapy and immune checkpoint blockade therapy response.

Topical Protease Inhibitor Decreases Anal Carcinogenesis in a Transgenic Mouse Model of HPV Anal Disease

Anal cancer is a major health problem. This study seeks to determine if the topical protease inhibitor Saquinavir (SQV), is effective at the prevention of anal cancer in transgenic mice with established anal dysplasia. K14E6/E7 mice were entered into the study when the majority spontaneously developed high-grade anal dysplasia. To ensure carcinoma development, a subset of the mice was treated with a topical carcinogen: 7,12-Dimethylbenz[a]anthracene (DMBA). Treatment groups included: no treatment, DMBA only, and topical SQV with/without DMBA. After 20 weeks of treatment, anal tissue was harvested and evaluated histologically. SQV was quantified in the blood and anal tissue, and tissue samples underwent analysis for E6, E7, p53, and pRb. There was minimal systemic absorption of SQV in the sera despite high tissue concentrations. There were no differences in tumor-free survival between SQV-treated and respective control groups but there was a lower grade of histological disease in the mice treated with SQV compared to those untreated. Changes in E6 and E7 levels with SQV treatment suggest that SQV may function independently of E6 and E7. Topical SQV decreased histological disease progression in HPV transgenic mice with or without DMBA treatment without local side effects or significant systemic absorption.

The Use of the Protease Inhibitor, Saquinavir, to Treat Anal Cancer Spheroids Derived From Human Papillomavirus Transgenic Mice

BACKGROUND

Anal cancer is associated with high-risk human papillomavirus infection and oncoprotein expression. We have identified several protease inhibitors, used to treat HIV, that decrease oncogene expression.

OBJECTIVE

The aim of this project is to determine whether saquinavir, a protease inhibitor, results in a treatment response in anal cancer spheroids.

DESIGN

K14E6/E7 transgenic mice (n = 5), which express human papillomavirus 16 oncoproteins E6 and E7 in their epithelium, were treated topically at the anus with a carcinogen, 7,12-dimethylbenz[a]anthracene, to promote anal tumor growth. Tumors were excised and digested, and cells were plated. The tumor cells form 3D multicellular aggregates known as spheroids.

SETTINGS

This study was performed in an American Association for Accreditation of Laboratory Animal Care-approved facility.

INTERVENTIONS

Spheroids were placed in treatment groups: no treatment, vehicle (dimethyl sulfoxide), and 15 μM saquinavir. Spheroids were imaged immediately pretreatment and 24 hours posttreatment.

MAIN OUTCOME MEASURES

Spheroid diameters were measured using ImageJ and mean percent reduction was calculated for each spheroid to determine treatment effect on spheroid growth. Analysis of variance using pairwise comparisons was performed with Fisher protected least significant difference tests.

RESULTS

The no-treatment (n = 119 spheroids) and vehicle (n = 126 spheroids) groups demonstrated an increase in spheroid diameter during the treatment period. In contrast, spheroids treated with saquinavir (n = 151 spheroids) demonstrated a statistically significant percent reduction compared to the no-treatment ( p < 0.0001) and vehicle ( p = 0.002) groups.

LIMITATIONS

A limitation of these data is that some human error is likely present given that images were analyzed by 3 different scientists.

CONCLUSIONS

Saquinavir leads to a statistically significant percent reduction in mice anal tumor spheroid growth ex vivo compared to control groups. Protease inhibitor therapy may be an effective treatment or adjuvant therapy to the Nigro protocol to promote anal cancer tumor regression. See Video Abstract at http://links.lww.com/DCR/C82 .

EL USO DEL INHIBIDOR DE LA PROTEASA, SAQUINAVIR, PARA TRATAR LOS ESFEROIDES DEL CNCER ANAL DERIVADOS DE RATONES TRANSGNICOS PARA EL VPH

ANTECEDENTES:El cáncer anal está asociado con la infección por el virus del papiloma humano de alto riesgo y la expresión de oncoproteínas. Hemos identificado varios inhibidores de la proteasa, utilizados para tratar el VIH, que disminuyen la expresión del oncogén.OBJETIVO:El objetivo de este proyecto es determinar si los esferoides de cáncer anal responden al tratamiento con inhibidor de la proteasa, Saquinavir.DISEÑO:Ratones transgénicos K14E6/E7 (n = 5), que expresan las oncoproteínas E6 y E7 del VPH16 en su epitelio, fueron tratados tópicamente en el ano con carcinógeno, 7,12 dimetilbenz[a]antraceno, para promover el crecimiento del tumor anal. Los tumores se extirparon y digirieron, y las células se sembraron en placas. Las células tumorales forman agregados multicelulares tridimensionales, conocidos como esferoides.ESCENARIO:Este estudio se realizó en un centro aprobado por la Asociación Estadounidense para la Acreditación de Cuidado de Animales de Laboratorio.INTERVENCIONES:Se colocaron esferoides en grupos de tratamiento: sin tratamiento, vehículo (sulfóxido de dimetilo) y saquinavir 15 μM. Se tomaron imágenes de los esferoides inmediatamente antes del tratamiento y 24 horas después del tratamiento.PRINCIPALES MEDIDAS DE RESULTADO:Los diámetros de los esferoides se midieron con ImageJ y se calculó el porcentaje medio de reducción de cada esferoide para determinar el efecto del tratamiento sobre el crecimiento de los esferoides. El análisis de varianza mediante comparaciones por pares se realizó con las pruebas de diferencia mínima significativa protegida de Fisher.RESULTADOS:Los grupos sin tratamiento (n =119 esferoides) y vehículo (n=126 esferoides) demostraron un aumento en el diámetro del esferoide durante el período de tratamiento. Por el contrario, los esferoides tratados con saquinavir (n =151 esferoides) demostraron una reducción porcentual estadísticamente significativa en comparación con los grupos sin tratamiento ( p < 0,0001) y con vehículo (p = 0,002).LIMITACIONES:una limitación de estos datos es que es probable que haya algún error humano dado que las imágenes fueron analizadas por tres científicos diferentes.CONCLUSIONES:Saquinavir conduce a una reducción porcentual estadísticamente significativa en el crecimiento de esferoides de tumores anales en ratones ex-vivo en comparación con los grupos de control. La terapia con inhibidores de la proteasa puede ser un tratamiento eficaz o una terapia adyuvante del protocolo Nigro para promover la regresión del tumor del cáncer anal. Consulte Video Resumen en http://links.lww.com/DCR/C82 . (Traducción-Dr. Felipe Bellolio ).

Anal Cancer Prevention Through the Topical Use of Single or Dual PI3K/mTOR Inhibitors

INTRODUCTION

Anal dysplasia and anal cancer are major health problems. This study seeks to determine if inhibition of mTOR and/or PI3K pathways is effective at anal cancer prevention in mice with/without established precancerous lesions of the anus (anal dysplasia).

METHODS

K14E6/E7 mice were entered into the study at 5 wk, 15 wk, or 25 wk of age. Mice were treated with a topical carcinogen, 7,12-Dimethylbenz[a]anthracene (DMBA), which ensures carcinoma development within 20 wk. Treatment groups included: no treatment, DMBA only, topical Pictilisib (PI3K inhibitor) with/without DMBA, topical Sapanisertib (mTOR inhibitor) with/without DMBA, and topical Samotolisib (dual PI3K/mTOR inhibitor) with/without DMBA. Mice underwent weekly observations for anal tumor development (tumor-free survival). After 20 wk of treatment, anal tissue was harvested and evaluated histologically for squamous cell carcinoma (SqCC).

RESULTS

All topical treatments in conjunction with DMBA increased tumor-free survival in mice that started treatment at 15 wk of age when compared to DMBA-only treatment, except for Pictilisib + DMBA in males. Topical Sapanisertib increased tumor-free survival in mice regardless of starting treatment age. When examining tissue for microscopic evidence of SqCC, only topical Samotolisib in males decreased SqCC in the 15 wk starting mice.

CONCLUSIONS

Sapanisertib, the mTOR inhibitor, had the greatest effect, in terms of increasing tumor-free survival, regardless of starting time point or sex. Unlike the other treatments, Samotolisib, the dual PI3K/mTOR inhibitor, decreased microscopic evidence of SqCC when starting treatment at 15 wk of age but only in male mice.

The use of a topical protease inhibitor, Saquinavir, to alleviate mouse papillomavirus-mediated anal disease

Select protease inhibitors (PI) have been found to be effective in decreasing human papillomavirus oncoprotein expression. This study evaluated whether the topical PI, Saquinavir (SQV), promotes viral clearance in an infectious mouse model with Mus musculus papillomavirus 1 (MmuPV1). NOD scid gamma (NSG) mice were anally infected with ∼4 × 10⁸ viral genome equivalents of MmuPV1 and 120 days post-infection (when majority have high-grade anal dysplasia), began topical treatments: control (mock), 7,12-dimethylbenz(a)anthracene (DMBA) only, once weekly to promote carcinogenesis, 1% SQV only, daily (Monday - Friday), and SQV + DMBA. Viral MmuPV1 load was analyzed from anal lavages pre and post-treatment. Anal tissue was harvested, processed, and evaluated for drug absorption, grade of anal disease, and anal viral RNA. Results suggest that topical SQV promotes decreased viral shedding in female mice treated with SQV.

Efficacy of Topically Administered Dihydroartemisinin in Treating Papillomavirus-Induced Anogenital Dysplasia in Preclinical Mouse Models

The artemisinin family of compounds is cytopathic in certain cancer cell lines that are positive for human papillomaviruses (HPV) and can potentially drive the regression of dysplastic lesions. We evaluated the efficacy of topical dihydroartemisinin (DHA) on cervical dysplasia and anal dysplasia in two papillomavirus mouse models: K14E6/E7 transgenic mice, which express HPV16 oncogenes; and immunodeficient NOD/SCID gamma (NSG) mice infected with Mus musculus papillomavirus (MmuPV1). Mice started treatment with DHA at 25 weeks of age (K14E6/E7) or 20 weeks post infection (MmuPV1-infected), when the majority of mice are known to have papillomavirus-induced low- to high-grade dysplasia. Mice were treated with or without topical DHA at the cervix or anus and with or without topical treatment with the chemical carcinogen 7,12 dimethylbenz(a)anthracene (DMBA) at the anus of in transgenic mice to induce neoplastic progression. Mice were monitored for overt tumor growth, and tissue was harvested after 20 weeks of treatment and scored for severity of histological disease. For MmuPV1-infected mice, anogenital lavages were taken to monitor for viral clearance. Tissues were also evaluated for viral gene expression at the RNA and/or protein levels. Treatment with topical DHA did not reduce dysplasia in the anogenital tract in either papillomavirus-induced mouse model and did not prevent progression to anal cancer in the DMBA-treated K14E6/E7 mice.

Systemic Delivery of a Dual PI3K/mTOR Inhibitor More Effective than Topical Delivery in Preventing Anal Carcinogenesis in an HPV Transgenic Mouse Model

Introduction

Anal dysplasia is a growing health concern that over time can result in squamous cell carcinoma (SqCC) of the anus. In this study, we compare a topical versus systemic (oral) administration of LY3023414, a dual PI3K/mTOR inhibitor, to prevent anal carcinogenesis in a Human Papillomavirus (HPV) mouse model of anal cancer.

Materials and Methods

K14E6/E7 transgenic mice were used to model HPV-induced anal carcinogenesis. Mice with varying starting anal histologies (normal histology, low-grade, and high-grade anal dysplasia) were treated topically at the anus or systemically via oral gavage with LY3023414 with or without topical carcinogen for 20 weeks. Mice were monitored for overt anal tumor development and anal tissue was assessed for histology and markers of PI3K and mTOR activity (pAKT and pS6, respectively).

Results

LY3023414 treatment, regardless of the mode of delivery, significantly decreased overt tumor development in mice starting with normal histology and low-grade anal dysplasia. Systemic LY3023414 treatment was more effective in delaying tumor onset than topical treatment. Mice treated with systemic LY3023414 had significantly reduced rates of anal SqCC when starting with normal and low-grade anal dysplasia compared to topical treatment. Topical treatment was only effective in reducing SqCC in the setting of low-grade dysplasia. LY3023414 inhibition of pAKT and pS6 expression varied with starting histology. Neither treatment mode was effective in the setting of high-grade anal dysplasia.

Conclusion

Systemic LY3023414 treatment was more effective than topical application in delaying the progression of normal anal histology and low-grade dysplasia to anal cancer in HPV-associated mice.

The Optimal Ileal Pouch: Physiologic Parameters Significantly Correlate with Overall Pouch Function

BACKGROUND

Ileal pouch function is affected by several patient factors and pouch physiology. The significance of pouch physiology on optimal pouch function has not been well characterized. The purpose of this study was to examine specific post-ileal pouch anal anastomosis (IPAA) physiologic parameters to determine impact on pouch function and quality of life.

METHODS

Patients undergoing proctocolectomy with IPAA for ulcerative colitis were examined. Post-IPAA compliance, pouch anal pressure gradient (PAPG), and function were assessed 6-8 months postoperatively. Compliance was calculated as change in volume divided by change in pressure. PAPG was calculated as the difference between anal pressure and intra-pouch pressure at a fixed volume. Pouch function evaluation included stool frequency and episodes of incontinence. Quality of life was evaluated using the Rockwood Fecal Incontinence Quality of Life Scale.

RESULTS

A total of 125 patients were investigated. Post-IPAA resting anal pressure averaged 58.1 ± 15 mmHg. Mean volume and intra-pouch pressure at evacuation were 245 mL and 33.9 mmHg, respectively. Compliance averaged 11.2 mmHg/mL with a mean PAPG of - 29.3 mmHg. Compliance and PAPG correlated with 24-h (p = 0.003, p = 0.004) and nighttime stool frequency (p = 0.04, p = 0.03). Daytime continence was impacted by compliance (p = 0.04), PAPG (p = 0.02), and resting anal pressure (p = 0.02).

CONCLUSION

This unique evaluation reveals a significant correlation between IPAA physiologic properties and function. Optimal function and quality of life depend in part on maintaining optimal pouch compliance and pressure differentials between the pouch and anal canal, defined by the pouch anal pressure gradient.

HIV-1 Protease Inhibitors Slow HPV16-Driven Cell Proliferation through Targeted Depletion of Viral E6 and E7 Oncoproteins

High-risk human papillomavirus strain 16 (HPV16) causes oral and anogenital cancers through the activities of two viral oncoproteins, E6 and E7, that dysregulate the host p53 and pRb tumor suppressor pathways, respectively. The maintenance of HPV16-positive cancers requires constitutive expression of E6 and E7. Therefore, inactivating these proteins could provide the basis for an anticancer therapy. Herein we demonstrate that a subset of aspartyl protease inhibitor drugs currently used to treat HIV/AIDS cause marked reductions in HPV16 E6 and E7 protein levels using two independent cell culture models: HPV16-transformed CaSki cervical cancer cells and NIKS16 organotypic raft cultures (a 3-D HPV16-positive model of epithelial pre-cancer). Treatment of CaSki cells with some (lopinavir, ritonavir, nelfinavir, and saquinavir) but not other (indinavir and atazanavir) protease inhibitors reduced E6 and E7 protein levels, correlating with increased p53 protein levels and decreased cell viability. Long-term (>7 day) treatment of HPV16-positive NIKS16 raft cultures with saquinavir caused epithelial atrophy with no discernible effects on HPV-negative rafts, demonstrating selectivity. Saquinavir also reduced HPV16's effects on markers of the cellular autophagy pathway in NIKS16 rafts, a hallmark of HPV-driven pre-cancers. Taken together, these data suggest HIV-1 protease inhibitors be studied further in the context of treating or preventing HPV16-positive cancers.

Preoperative Tamsulosin to Prevent Postoperative Urinary Retention: A Randomized Controlled Trial

BACKGROUND

The purpose of this study was to evaluate the efficacy of tamsulosin, administered preoperatively, for the prevention of postoperative urinary retention (POUR). POUR is a common complication of abdominal surgery, leading to the use of urinary catheters, which are a risk factor for urinary tract infection. Tamsulosin is a uroselective alpha-1a blocker used for the treatment of lower urinary tract symptoms.

MATERIALS AND METHODS

A randomized, double-blind, placebo-controlled trial was undertaken from August 2015 to May 2018. Adults undergoing elective inpatient abdominal surgery were randomized to receive either tamsulosin 0.4 mg or placebo daily for 7 d before surgery and continuing for up to 7 d postoperatively. The primary outcome was need for at least a single intermittent catheterization postoperatively. Secondary outcomes included first postvoid residual volume, number of catheterizations, need for replacement of an indwelling catheter, hospital length of stay, and urinary tract infection within 30 d of surgery.

RESULTS

A total of 158 participants were enrolled, with a final analytic cohort of 141 participants. The two groups had similar baseline characteristics, operative characteristics, and timing of catheter removal. There was no difference in the incidence of POUR between the two groups (26% in tamsulosin versus 31% in placebo, P = 0.49). There was also no difference in any of the secondary outcomes between the two groups. Epidural usage, open surgery, and age <50 were identified as risk factors for POUR.

CONCLUSIONS

Perioperative prophylaxis with tamsulosin is not effective in reducing the incidence of POUR in patients undergoing elective abdominal surgery.

Abstract 2701: Patient-derived colorectal cancer organoid therapeutic escalation: Tracking resistance to EGFR inhibition for predicting therapeutic sensitivity

Background: Precision oncology requires translational tools predictive of clinical benefit. Epidermal growth factor receptor inhibition (EGFRi) yields a survival advantage in RAS/RAF wildtype (wt) colorectal cancer (CRC), however clinical tools do not predict individual patient response or resistance mechanisms. Patient-derived cancer organoids (PDCOs) allow for an ex vivo method to track subclonal response. Here, we examine the development of PDCO EGFRi resistance as a novel biomarker to differentiate treatment sensitivities.

Methods: Fresh CRC tissue was obtained following consent to an IRB-approved protocol. Molecular profiling was performed on expanded PDCOs and in parallel to clinical hotspot sequencing. Cultures were treated with stepwise (20%) increases in panitumumab (46ug/mL per escalation) up to the physiologic Cmax (230ug/mL). A HER2 amplified culture was also assessed by escalation of trastuzumab with 20% stepwise increase to physiologic Cmax (180ug/mL). Threshold for escalation to the next dose level was a median relative growth of 20% at 96h. Time to resistance (TTR) was defined from start to persistent PDCO growth at 100% Cmax. Treatment studies assessed the longest diameter of individual spheres, assessed at 48h and compared to control using effect size (Glass's (G) Δ). TTR was compared to molecular profiles of primary resistance and clinical outcomes.

Results: CRC PDCOs were derived from 10 patients (5 localized and 5 metastatic samples). PDCOs had diverse molecular profiles: 3 KRAS mutant (mt), 1 PTEN mt, 7 TP53 mt, and 7 RAS/RAF wt. TTR ranged from 26-226 days, with 90% of PDCOs lines achieving resistance. RAS mt PDCOs had a homogeneous TTR of 27.0±1.4 days. RAS wt PDCOs displayed marked variation in therapeutic response with TTR of 51.5±61.7 days (p=0.06, compared to RAS mt). A HER2-amplified PDCO (copy number 14) showed intermediate sensitivity to EGFRi (TTR 55 days), similar to dose escalation of HER2-targeting trastuzumab (TTR of 51 days). This HER2-amplified PDCO showed intermediate sensitivity to single agent trastuzumab (GΔ = 0.56), yet no sensitivity to trastuzumab following EGFRi resistance (GΔ = 0.09). Prospective clinical correlation was possible for 1 PDCO line, a RAS wt PDCO derived prior to EGFRi which showed marked sensitivity with growth and metabolic arrest achieved at 40% CMax consistent with clinical response.

Conclusions: We present therapeutic dose escalation using PDCOs as a translational tool to track the clonal dynamics of resistance to EGFRi in CRC. This technique provides an objective measure of TTR to differentiate culture specific sensitivity in a clinically relevant timeframe. Molecular profiling of resistant cultures is ongoing which may provide an ex vivo tool for predicting individual resistance as cancers evade therapeutic pressure of targeted selection.

Citation Format: Jeremy D. Kratz, Aishwarya Sunil, Meghan Conroy, Cheri A. Pasch, Nicole Lassen, Hannah Houtler, Kayla K. Lemmon, Linda Clipson, Daniel E. Abbott, Evie H. Carchman, Elise H. Lawson, Noelle K. Loconte, Sam J. Lubner, Kristina A. Matkowskyj, Daniel L. Mulkerin, Nataliya Uboha, Dustin A. Deming. Patient-derived colorectal cancer organoid therapeutic escalation: Tracking resistance to EGFR inhibition for predicting therapeutic sensitivity [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2701.

Patient-Derived Cancer Organoid Cultures to Predict Sensitivity to Chemotherapy and Radiation

PURPOSE

Cancer treatment is limited by inaccurate predictors of patient-specific therapeutic response. Therefore, some patients are exposed to unnecessary side effects and delays in starting effective therapy. A clinical tool that predicts treatment sensitivity for individual patients is needed.

EXPERIMENTAL DESIGN

Patient-derived cancer organoids were derived across multiple histologies. The histologic characteristics, mutation profile, clonal structure, and response to chemotherapy and radiation were assessed using bright-field and optical metabolic imaging on spheroid and single-cell levels, respectively.

RESULTS

We demonstrate that patient-derived cancer organoids represent the cancers from which they were derived, including key histologic and molecular features. These cultures were generated from numerous cancers, various biopsy sample types, and in different clinical settings. Next-generation sequencing reveals the presence of subclonal populations within the organoid cultures. These cultures allow for the detection of clonal heterogeneity with a greater sensitivity than bulk tumor sequencing. Optical metabolic imaging of these organoids provides cell-level quantification of treatment response and tumor heterogeneity allowing for resolution of therapeutic differences between patient samples. Using this technology, we prospectively predict treatment response for a patient with metastatic colorectal cancer.

CONCLUSIONS

These studies add to the literature demonstrating feasibility to grow clinical patient-derived organotypic cultures for treatment effectiveness testing. Together, these culture methods and response assessment techniques hold great promise to predict treatment sensitivity for patients with cancer undergoing chemotherapy and/or radiation.

Defecography: An Overview of Technique, Interpretation, and Impact on Patient Care

Pelvic floor and defecatory dysfunction are common in the female patient population. When combined with physical examination, barium defecography allows for accurate and expanded assessment of the underlying pathology and helps to guide future intervention. Understanding the imaging findings of barium defecography in the spectrum of pathology of the anorectum and pelvic floor allows one to appropriately triage and treat patients presenting with defecatory dysfunction.

Genetic inhibition of autophagy in a transgenic mouse model of anal cancer

BACKGROUND:

The dynamic role of autophagy in cancer development is a topic of considerable research and debate. Previously published studies have shown that anal cancer development can be promoted or prevented with the pharmacologic inhibition or induction, respectively, of autophagy in a human papillomavirus (HPV) mouse model. However, these results are confounded by the fact that the drugs utilized are known to affect other pathways besides autophagy. It has also been shown that autophagic inhibition occurs in the setting of HPV16 oncoprotein expression (E6 and E7) and correlates with increased susceptibility to anal carcinogenesis.

MATERIALS AND METHODS:

In this study, we employed a conditional, genetic, autophagic (Atg7) knockout mouse model to determine conclusively that autophagy has a role in anal cancer development, in the absence or presence of E6 and E7.

RESULTS:

In mice lacking both HPV16 oncogenes, knockout of autophagy followed by exposure to a carcinogen resulted in a tumor incidence of 40%, compared to 0% in mice treated with a carcinogen alone with an intact autophagic pathway (P = 0.007). In mice expressing either one or both HPV16 oncoproteins, the addition of genetic knockout of autophagy to carcinogen treatment did not lead to a significant difference in tumor incidence compared to carcinogen treatment alone, consistent with the ability of HPV oncogenes to inhibit autophagy in themselves.

CONCLUSIONS:

These results provide the first conclusive evidence for the distinct role of autophagy in anal carcinogenesis, and suggest that autophagy is a plausible target for therapies aimed at reducing anal dysplasia and anal cancer development.

The role of pharmacologic modulation of autophagy on anal cancer development in an HPV mouse model of carcinogenesis

Autophagy is an intracellular, catabolic process that maintains cellular health. We examined the response of pharmacologic modulation of autophagy in an HPV mouse model of anal carcinogenesis. K14E6/E7 mice were treated with the topical carcinogen DMBA weekly and assessed for tumors over 20 weeks. Concurrently, they were given either chloroquine or BEZ235, to inhibit or induce autophagy, respectively. Time to tumor onset was examined. Immunofluorescence (IF) was performed for LC3β and p62 to examine autophagy. All DMBA treated K14E6/E7 mice developed anal cancer, contrary to zero of the no DMBA treated mice. Chloroquine plus DMBA resulted in a significant decrease in the time to tumor onset compared to K14E6/E7 treated with DMBA. Only 40% BEZ235 plus DMBA treated mice developed anal cancer. Autophagic induction with DMBA and BEZ235, and autophagic inhibition with chloroquine were confirmed via IF. Anal carcinogenesis can be inhibited or induced via pharmacologic modulation of autophagy.

Preoperative blood transfusion is a predictor of worse short-term postoperative outcomes after colectomy

BACKGROUND

Both anemia and blood transfusion are associated with poor outcomes. The aim of this study was to evaluate the effect of preoperative blood transfusion on postoperative outcomes after colectomy, stratified by severity of anemia.

METHODS

Patients undergoing colectomy from 2012-2014 were selected from the National Surgical Quality Improvement Program targeted colectomy database. Patients were divided into 2 groups based on receipt of preoperative transfusion and then stratified by hematocrit. Univariate and multivariate analyses were used to compare 30-day outcomes between the 2 groups.

RESULTS

A total of 60,785 patients were included in the study, with an overall preoperative transfusion rate of 3.4% (n = 2,073). On univariate analysis, transfusion was associated with significantly greater rates of postoperative morbidity. The risk-adjusted, multivariate model confirmed increased risk of complications with preoperative transfusion (odds ratio 1.32, 95% confidence interval, 1.18-1.48). Furthermore, transfusion did not improve outcomes even in the setting of moderate anemia (odds ratio 1.35, 95% confidence interval, 1.14-1.60) or severe anemia (odds ratio 0.97, 95% confidence interval, 0.66-1.41).

CONCLUSIONS

Preoperative transfusion is an independent predictor of complications in patients with mild and moderate anemia. Furthermore, these retrospective data suggest that even severely anemic patients do not benefit from preoperative transfusion and empiric transfusion therefore should be avoided. Alternatives to preoperative optimization of this high-risk surgical population should be sought.

Dysregulation of Autophagy Contributes to Anal Carcinogenesis

Introduction

Autophagy is an intracellular catabolic process that removes and recycles unnecessary/dysfunctional cellular components, contributing to cellular health and survival. Autophagy is a highly regulated cellular process that responds to several intracellular signals, many of which are deregulated by human papillomavirus (HPV) infection through the expression of HPV-encoded oncoproteins. This adaptive inhibitory response helps prevent viral clearance. A strong correlation remains between HPV infection and the development of squamous cell carcinoma (SCC) of the anus, particularly in HIV positive and other immunosuppressed patients. We hypothesize that autophagy is inhibited by HPV–encoded oncoproteins thereby promoting anal carcinogenesis (Fig 1).

Materials and Methods

HPV16 transgenic mice (K14E6/E7) and non-transgenic mice (FVB/N), both of which do not spontaneously develop anal tumors, were treated topically with the chemical carcinogen, 7,12-Dimethylbenz[a]anthracene (DMBA), to induce anal cancer. The anuses at different time points of treatment (5, 10, 15 and 20 weeks) were analyzed using immunofluorescence (IF) for two key autophagy marker proteins (LC3β and p62) in addition to histological grading. The anuses from the K14E6/E7 mice were also analyzed for visual evidence of autophagic activity by electron microscopy (EM). To see if there was a correlation to humans, archival anal specimens were assessed histologically for grade of dysplasia and then analyzed for LC3β and p62 protein content. To more directly examine the effect of autophagic inhibition on anal carcinogenesis, nontransgenic mice that do not develop anal cancer with DMBA treatment were treated with a known pharmacologic inhibitor of autophagy, chloroquine, and examined for tumor development and analyzed by IF for autophagic proteins.

Results

Histologically, we observed the progression of normal anoderm to invasive SCC with DMBA treatment in K14E6/E7 mice but not in nontransgenic, syngeneic FVB/N background control mice. With the development of low-grade dysplasia in the K14E6/E7 mice, there was an increase in both punctate LC3β and p62 expression while EM revealed increased autophagosomes without evidence of autophagolysosomes. These observations are consistent with autophagy being inhibited at a later stage in the autophagic process. In contrast, in high-grade dysplasia and SCC in the DMBA-treated K14E6/E7 mice, there were decreased levels of p62 with a continued increase in punctate LC3β expression by IF, while autophagolysosomes were seen on EM, consistent with the process of autophagy proceeded to completion. Similar findings, including histological grade dependent changes in LC3β and p62 expression, were noted with human samples upon analysis of IF. Finally, with pharmacologic inhibition of autophagy in DMBA-treated, nontrangenic FVB/N mice, there was a significant increase in anal cancer development similar to that observed in DMBA- treated K14E6/E7 mice.

Conclusion

Autophagic dysregulation is noted early on in HPV-associated anal carcinogenesis (low-grade dysplasia), with normalization of the autophagic process arising in late stages of HPV-associated anal carcinogenesis (high-grade dysplasia and invasive carcinoma).

Short-term outcomes of minimally invasive versus open colectomy for colon cancer

BACKGROUND

Laparoscopic and open approaches to colon resection have equivalent long-term outcomes and oncologic integrity for the treatment of colon cancer. Differences in short-term outcomes should therefore help to guide surgeons in their choice of operation. We hypothesized that minimally invasive colectomy is associated with superior short-term outcomes compared to traditional open colectomy in the setting of colon cancer.

MATERIALS AND METHODS

Patients undergoing nonemergent colectomy for colon cancer in 2012 and 2013 were selected from the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) targeted colectomy participant use file. Patients were divided into two cohorts based on operative approach-open versus minimally invasive surgery (MIS). Univariate, multivariate, and propensity-adjusted multivariate analyses were performed to compare postoperative outcomes between the two groups.

RESULTS

A total of 11,031 patients were identified for inclusion in the study, with an overall MIS rate of 65.3% (n = 7200). On both univariate and multivariate analysis, MIS approach was associated with fewer postoperative complications and lower mortality. In the risk-adjusted multivariate analysis, MIS approach was associated with an odds ratio of 0.598 for any postoperative morbidity compared to open (P < 0.001).

CONCLUSIONS

This retrospective study of patients undergoing colectomy for colon cancer demonstrates significantly improved outcomes associated with a MIS approach, even when controlling for baseline differences in illness severity. When feasible, minimally invasive colectomy should be considered gold standard for the surgical treatment of colon cancer.

National Trends in Short-term Outcomes Following Non-emergent Surgery for Diverticular Disease

INTRODUCTION

Elective surgery for diverticulitis has evolved over the last decade. We aimed to evaluate the impact of changing practice patterns on postoperative outcomes. We hypothesized that the increased use of laparoscopy, and other management changes, would correlate with a decrease in postoperative complications.

METHODS

Patients undergoing non-emergent surgery for diverticulitis from 2005 to 2013 were selected from the National Surgical Quality Improvement Program (NSQIP) database. We compared patient demographics, comorbidities, and operative approach by year of operation using chi-square tests and investigated temporal trends in postoperative outcomes using univariate, trend, and multivariate analyses.

RESULTS

The analytic cohort, which included 29,893 patients, had increasing rates of obesity, advanced age, and higher American Society of Anesthesiologists (ASA) class over the study period. The use of laparoscopy increased significantly from 48 % in 2005/2006 to 70 % in 2013 (p < 0.001), while the rate of stoma creation remained unchanged (10-12 %, p = 0.072). The absolute risk of any postoperative complication decreased by 5.8 % over the study period, driven primarily by a reduction in infectious complications. Year of operation was a significant independent predictor of fewer complications for 2011-2013.

CONCLUSION

Despite a trend towards increasing patient complexity, there has been a decline in postoperative morbidity following non-emergent surgery for diverticulitis. This trend coincides with the steadily increasing use of laparoscopy in this population.

Postoperative Ileus--More than Just Prolonged Length of Stay?

PURPOSE

Given that postoperative ileus is common in colectomy patients, we sought to examine the association of ileus with adverse events in this patient population.

METHODS

The ACS NSQIP puf file from 2012 to 2013 was queried for non-emergent colectomy cases. Predictors of other poor postoperative outcomes in patients who experienced postoperative ileus were assessed using chi-squared and multivariable regression analyses. Chi-squared analysis was used to assess for additive effects of ileus and other postoperative complications on mortality. p Values <0.05 were considered significant.

RESULTS

We identified 32,392 patients who underwent non-emergent colectomy. Longer length of stay, higher complication, reoperation, readmission, and mortality rates were identified in patients with ileus (p < 0.001 for all). Overall, 59% of patients with ileus had at least one adverse outcome, compared with 25% of patients without ileus (p < 0.001). Patients who developed ileus in the absence of other complications had an identical mortality rate to patients without ileus (1%). Additional complications led to incremental increases in mortality rates.

CONCLUSIONS

Patients with ileus and multiple complications are at significantly increased risk for adverse outcomes. Older patients with more comorbidity were found to be at risk for adverse outcomes in addition to ileus, begging the question of whether these patients may benefit from preoperative optimization.

Characterizing readmission in ulcerative colitis patients undergoing restorative proctocolectomy

BACKGROUND

Postoperative readmissions increase costs and affect patient quality of life. Ulcerative colitis (UC) patients are at a high risk for hospital readmission following restorative proctocolectomy (RP).

OBJECTIVE

The objective of this study is to characterize UC patients undergoing RP and identify causes and risk factors for readmission.

DESIGN

A retrospective review of a prospectively maintained institutional database was performed. Postoperative readmission rates and reasons for readmission were examined following RP. Univariate and multivariate analyses were performed to evaluate for risk factors associated with readmission.

RESULTS

Of 533 patients who met our inclusion criteria, 18.2 % (n = 97) were readmitted within 30 days while 22.7 % (n = 121) were readmitted within 90 days of stage I of RP. Younger patient age (OR 1.825, 95 % CI 1.139-2.957), laparoscopic approach (OR 1.943, 95 % CI 1.217-3.104), and increased length of initial stay (OR 1.155, 95 % CI 1.090-1.225) were all associated with 30-day readmission. The most common reason for readmission was dehydration/ileus/partial bowel obstruction, with 10 % of patients readmitted for this reason within 30 days.

CONCLUSIONS

Patients undergoing restorative proctocolectomy are at high risk for readmission, particularly following the first stage of the operation. Novel treatment pathways to prevent ileus and dehydration as an outpatient may decrease the rates of readmission following RP.

Polymicrobial sepsis is associated with decreased hepatic oxidative phosphorylation and an altered metabolic profile

BACKGROUND

Organ failure in sepsis accounts for significant mortality worldwide. Mitochondrial and metabolic responses are central to the overall response of the cell, and thus of the organ and organism. Adaptive responses in metabolism are critical to the recovery at the cellular level. The purpose of these investigations was to test the hypothesis that sepsis is associated with decreased aerobic respiration and significant metabolic changes in the liver.

METHODS

C57BL/6 mice underwent cecal ligation and puncture (CLP) with a 21 gauge needle or an operation without CLP. Mice were euthanized from 0-24 h after the procedure and liver tissue was harvested. Tissue oxygen consumption and mitochondrial complex activity were measured. Global biochemical profiles of 311 metabolites were performed at the 8-h time point (n = 8/group) and analyzed by gas chromatography-mass spectrometry and liquid chromatography tandem mass spectrometry platforms by Metabolon (Durham, North Carolina). The influence of lipopolysaccharide (LPS) on aerobic and anaerobic respiration in primary mouse hepatocytes was also investigated.

RESULTS

CLP in vivo or LPS in vitro resulted in a significant decrease in hepatic oxygen consumption. There was a significant decrease in oxidative phosphorylation measured at 12 h. LPS also resulted in a significant increase in anaerobic respiration in hepatocytes. Interestingly, the metabolomic analysis resulted in a metabolic shift in the liver from carbohydrate-based energy to utilization of fatty acids and amino acids. This included an increase in every tricarboxylic acid cycle intermediate and derivative, suggesting an increased flux into the cycle from fatty acid beta-oxidation and anaplerotic contributions from amino acids.

CONCLUSIONS

Sepsis results in a metabolic response and profile consistent with increased anaerobic respiration, which occurs prior to significant changes in hemodynamics. The metabolic responses of cells and organs may be important adaptive responses to prevent organ failure and death.

Experimental sepsis-induced mitochondrial biogenesis is dependent on autophagy, TLR4, and TLR9 signaling in liver

Organ injury in sepsis is initially characterized by dysfunction without cell death and structural damage, and thus with the ability to recover organ function. Adaptive metabolic responses to sepsis can prevent bioenergetic failure and death. These studies were aimed at investigating the influence of sepsis on mitochondrial homeostasis, focusing on removal of dysfunctional mitochondria and restitution of a healthy mitochondrial population. These data demonstrate decreased hepatic oxidative phosphorylation by 31 ± 11% following murine cecal ligation and puncture (CLP) at 8 h and 34 ± 9% following LPS treatment in vitro at 12 h (P<0.05). In addition, there was a loss of mitochondrial membrane potential. Mitochondrial density and number initially decreased (relative area per micrograph of 64±10% at baseline vs. 39±13% at 8 h following LPS; P<0.05) and was associated with an increase in autophagy and mitophagy. CLP-induced markers of mitochondrial biogenesis and mitochondrial number and density recovered over time. Furthermore, these data suggest that mitochondrial biogenesis was dependent on an autophagy and mitochondrial DNA/Toll-like receptor 9 (TLR9) signaling pathway. These results suggest that hepatocyte survival and maintenance of function in sepsis is dependent on a mitochondrial homeostasis pathway marked by mitophagy and biogenesis.

CaMKIα regulates AMP kinase-dependent, TORC-1-independent autophagy during lipopolysaccharide-induced acute lung neutrophilic inflammation

Autophagy is an evolutionarily conserved cytoplasmic process regulated by the energy rheostats mammalian target of rapamycin and AMP kinase (AMPK) that recycles damaged or unused proteins and organelles. It has been described as an important effector arm of immune cells. We have shown that the cytoplasmically oriented calcium/calmodulin-dependent protein kinase (CaMK)Iα regulates the inflammatory phenotype of the macrophage (M). In this study, we hypothesize that CaMKIα mediates M autophagy. LPS induced autophagy in RAW 264.7 cells and murine peritoneal M that was attenuated with biochemical CaMK inhibition or CaMKIα small interfering RNA (siRNA). Inhibition of CaMKIα reduced LPS-induced p-Thr(172)AMPK and target of rapamycin complex-1 activity, and expression of a constitutively active CaMKIα but not a kinase-deficient mutant induced p-Thr(172)AMPK and autophagy that was attenuated by the AMPK inhibitor compound C. Coimmunoprecipitation and in vitro kinase assays demonstrated that CaMKIα activates AMPK, thereby inducing ATG7, which also localizes to this CaMKIα/AMPK complex. During LPS-induced lung inflammation, C57BL/6 mice receiving CaMKIα(siRNA) displayed reduced lung and bronchoalveolar immune cell autophagy that correlated with reduced neutrophil recruitment, myeloperoxidase activity, and air space cytokine concentration. Independently inhibiting autophagy, using siRNA targeting the PI3K VPS34, yielded similar reductions in lung autophagy and neutrophil recruitment. Thus, a novel CaMKIα/AMPK pathway is rapidly activated in M exposed to LPS and regulates an early autophagic response, independent of target of rapamycin complex-1 inhibition. These mechanisms appear to be operant in vivo in orchestrating LPS-induced lung neutrophil recruitment and inflammation.

Novel management strategies in the treatment of severe Clostridium difficile infection

CDI is increasing in incidence and severity. Clinicians must have a low threshold to consider the diagnosis and to treat patients with the clinical syndrome and risk factors before laboratory confirmation of the diagnosis. In patients who have signs of advanced disease, escalation of care with antimicrobial strategies and multidisciplinary care including surgical consultation is necessary. Furthermore, lowering the threshold for surgery compared with traditional approaches likely results in improved survival. Novel surgical approaches may obviate total abdominal colectomy and the associated immediate and long-term morbidity in this often fragile patient population, thus allowing clinicians to embrace surgical therapy earlier in the course of severe, complicated disease.

Lipopolysaccaride induces autophagic signaling in macrophages via a TLR4, heme oxygenase-1 dependent pathway

Toll-like receptor (TLR) signaling is an important part of the innate immune response. One of the downstream responses to TLR4 signaling upon lipopolysaccharide (LPS) stimulation is the induction of autophagy, which is a key response to multiple stressors. An additional adaptive signaling molecule that is involved in the response to stress is heme oxygenase-1 (HO-1). HO-1 signaling is essential to limit inflammation and restore homeostasis. We found that LPS induced autophagic signaling in macrophages via a TLR4, HO-1 dependent pathway in macrophages. These data add to the developing contribution of autophagic signaling as part of the inflammatory response.

Heme oxygenase-1-mediated autophagy protects against hepatocyte cell death and hepatic injury from infection/sepsis in mice

Adaptive responses to sepsis are necessary to prevent organ failure and death. Cellular signaling responses that limit cell death and structural damage allow a cell to withstand insult from sepsis to prevent irreversible organ dysfunction. One such protective pathway to reduce hepatocellular injury is the up-regulation of heme oxygenase-1 (HO-1) signaling. HO-1 is up-regulated in the liver in response to multiple stressors, including sepsis and lipopolysaccharide (LPS), and has been shown to limit cell death. Another recently recognized rudimentary cellular response to injury is autophagy. The aim of these investigations was to test the hypothesis that HO-1 protects against hepatocyte cell death in experimental sepsis in vivo or LPS in vitro via induction of autophagy. These data demonstrate that both HO-1 and autophagy are up-regulated in the liver after cecal ligation and puncture (CLP) in C57BL/6 mice or in primary mouse hepatocytes after treatment with LPS (100 ng/mL). CLP or LPS results in minimal hepatocyte cell death. Pharmacological inhibition of HO-1 activity using tin protoporphyrin or knockdown of HO-1 prevents the induction of autophagic signaling in these models and results in increased hepatocellular injury, apoptosis, and death. Furthermore, inhibition of autophagy using 3-methyladenine or small interfering RNA specific to VPS34, a class III phosphoinositide 3-kinase that is an upstream regulator of autophagy, resulted in hepatocyte apoptosis in vivo or in vitro. LPS induced phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK), in part, via HO-dependent signaling. Moreover, inhibition of p38 MAPK prevented CLP- or LPS-induced autophagy.

CONCLUSION

Sepsis or LPS-induced autophagy protects against hepatocellular death, in part via an HO-1 p38 MAPK-dependent signaling. Further investigations are needed to elucidate how autophagic signaling prevents apoptosis and cell death.

Wild-type p53 and p73 negatively regulate expression of proliferation related genes

When normal cells come under stress, the wild-type (WT) p53 level increases resulting in the regulation of gene expression responsible for growth arrest or apoptosis. Here we show that elevated levels of WT p53 or its homologue, p73, inhibit expression of a number of cell cycle regulatory and growth promoting genes. Our analysis also identified a group of genes whose expression is differentially regulated by WT p53 and p73. We have infected p53-null H1299 human lung carcinoma cells with recombinant adenoviruses expressing WT p53, p73 or beta-galactosidase, and have undertaken microarray hybridization analyses to identify genes whose expression profile is altered by p53 or p73. Quantitative real-time PCR verified the repression of E2F-5, centromere protein A and E, minichromosome maintenance proteins (MCM)-2, -3, -5, -6 and -7 and human CDC25B after p53 expression. 5-Fluorouracil treatment of colon carcinoma HCT116 cells expressing WT p53 results in a reduction of the cyclin B2 protein level suggesting that DNA damage may indeed cause repression of these genes. Transient transcriptional assays verified that WT p53 repressed promoters of a number of these genes. Interestingly, a gain-of-function p53 mutant instead upregulated a number of these promoters in transient transfection. Using promoter deletion mutants of MCM-7 we have found that WT p53-mediated repression needs a minimal promoter that contains a single E2F site and surrounding sequences. However, a single E2F site cannot be significantly repressed by WT p53. Many of the genes identified are also repressed by p21. Thus, our work shows that WT p53 and p73 repress a number of growth-related genes and that in many instances this repression may be through the induction of p21.

Tumor-derived p53 mutants induce oncogenesis by transactivating growth-promoting genes

We have studied the mechanism of mutant p53-mediated oncogenesis using several tumor-derived mutants. Using a colony formation assay, we found that the majority of the mutants increased the number of colonies formed compared to the vector. Expression of tumor-derived p53 mutants increases the rate of cell growth, suggesting that the p53 mutants have 'gain of function' properties. We have studied the gene expression profile of cells expressing tumor-derived p53-D281G to identify genes transactivated by mutant p53. We report the transactivation of two genes, asparagine synthetase and human telomerase reverse transcriptase. Quantitative real-time PCR confirms this upregulation. Transient transfection promoter assays verify that tumor-derived p53 mutants transactivate these promoters significantly. An electrophoretic mobility shift assay shows that tumor-derived p53-mutants cannot bind to the wild-type p53 consensus sequence. The results presented here provide some evidence of a possible mechanism for mutant p53-mediated transactivation.