Abstract 6255: CRISPRa-mediated induction of apoptosis in therapy-resistant glioblastoma cells via derepression of pro-apoptotic genes

Induction of apoptosis in cancer cells via de-repressing dormant pro-apoptotic genes might be a successful therapeutic strategy. In this study, we utilized several dCas9-mediated CRISPR activation (CRISPRa) systems to activate two key pro-apoptotic genes DR4 and XAF1 in glioblastoma cells. CRISPRa is used to activate endogenous genes via either recruiting transcription factors or epigenetic modifiers to regulatory regions in the genome. Previously conducted studies showed that VPR, Suntag, and SAM systems are the most effective transcription factor-based systems for activating several genes in a variety of cell lines. However, epigenetic modifier-based systems that involve the recruitment of TET demethylases have more permanent effects. Therefore, we hypothesized that combinations of these systems may induce stronger activation. We systematically tested various CRISPRa systems and their combinations to activate XAF1 and DR4, which are known to be epigenetically silenced in drug-resistant glioblastoma cells. Inducing the expression of these genes, we aimed to observe apoptosis in glioblastoma cells either at a basal state or upon treatment with the pro-apoptotic ligand TRAIL. By transcriptomic alteration and cell viability analyses, we demonstrated that the combinatorial system including dCas9-TET1 and MS2-p65-hsf1 was the most efficient one for the activation of DR4 and XAF1 genes in both 293T and glioblastoma cells. Another system in which multiple TET1 enzymes were recruited to the gene promoter together with MS2-p65-hsf1 was found to be effective similarly, suggesting that the promoter demethylation is critical for the activation of these genes. Activation of these genes with the most efficient systems caused apoptosis and also sensitized glioblastoma cells to TRAIL treatment. Our preliminary work on measuring methylation levels of several CpG sites in the promoter regions of DR4 is in line with our observations of cell-based phenotypes. Together, our study indicates that the combination of transcription factor-based and demethylation-based CRISPR activation systems can induce pro-apoptotic gene expression in cancer cells and lead cancer cells to undergo apoptosis. Future applications of this methodology might involve the development of cancer-specific pro-apoptotic therapies.

[E.Y. and A.K. contributed equally to this work.]

Citation Format: Ebru Yilmaz, Alisan Kayabolen, Semra Cemre Atalar, Buket Yigit, Burge Ulukan, Mujdat Zeybel, Tugba Bagci-Onder. CRISPRa-mediated induction of apoptosis in therapy-resistant glioblastoma cells via derepression of pro-apoptotic genes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 6255.

Multiomics Analysis Reveals the Impact of Microbiota on Host Metabolism in Hepatic Steatosis

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a complex disease involving alterations in multiple biological processes regulated by the interactions between obesity, genetic background, and environmental factors including the microbiome. To decipher hepatic steatosis (HS) pathogenesis by excluding critical confounding factors including genetic variants and diabetes, 56 heterogenous MAFLD patients are characterized by generating multiomics data including oral and gut metagenomics as well as plasma metabolomics and inflammatory proteomics data. The dysbiosis in the oral and gut microbiome is explored and the host-microbiome interactions based on global metabolic and inflammatory processes are revealed. These multiomics data are integrated using the biological network and HS's key features are identified using multiomics data. HS is finally predicted using these key features and findings are validated in a follow-up cohort, where 22 subjects with varying degree of HS are characterized.

Fabrication and characterization of large numerical aperture, high-resolution optical fiber bundles based on high-contrast pairs of soft glasses for fluorescence imaging

Fabrication and characterization of flexible optical fiber bundles (FBs) with in-house synthesized high-index and low-index thermally matched glasses are presented. The FBs composed of around 15000 single-core fibers with pixel sizes between 1.1 and 10 μm are fabricated using the stack-and-draw technique from sets of thermally matched zirconium-silicate ZR3, borosilicate SK222, sodium-silicate K209, and F2 glasses. With high refractive index contrast pair of glasses ZR3/SK222 and K209/F2, FBs with numerical apertures (NAs) of 0.53 and 0.59 are obtained, respectively. Among the studied glass materials, ZR3, SK222, and K209 are in-house synthesized, while F2 is commercially acquired. Seven different FBs with varying pixel sizes and bundle diameters are characterized. Brightfield imaging of a micro-ruler and a Convallaria majalis sample and fluorescence imaging of a dye-stained paper tissue and a cirrhotic mice liver tissue are demonstrated using these FBs, demonstrating their good potential for microendoscopic imaging. Brightfield and fluorescence imaging performance of the studied FBs are compared. For both sets of glass compositions, good imaging performance is observed for FBs, with core diameter and core-to-core distance values larger than 1.6 μm and 2.3 μm, respectively. FBs fabricated with K209/F2 glass pairs revealed better performance in fluorescence imaging due to their higher NA of 0.59.

A custom-made silicon mold for pressure therapy to ear keloids

Keloids are raised reddish nodules that develop at the site of an injury. They are characterized histologically by an abundance of fibroblasts, thick collagen bundles, and ground substance. Auricular keloid formation is a known complication of ear piercing. Many types of treatments have been described for auricular keloids.Pressure therapy in combination with surgery, corticosteroid injection, or both is widely used to manage and prevent hypertrophic scarring. Many pressure devices and procedures have been developed. However, all of them are designed for the earlobe region. If a keloid grows in the posterior auricular region, none of the devices described in the literature will be effective. The authors developed a custom-made silicon ear mold that covers whole ear. With this mold, pressure can be applied homogeneously to the lobule and cartilaginous region, which the other devices described in the literature cannot affect. The preparation technique includes making the negative cast mold of the patient's ear, creating the positive cast mold from the negative cast mold, and forming the negative silicon mold from the positive cast. After all the processes, a silicon sheet has been designed according to the region needing to be pressurized. The designed silicon sheet is applied to the region, followed by placement of the silicon mold. A simple tennis head band can be used to stabilize the silicon cast. If the keloid extends to the posterior auricular region, pressurizing with clips or other devices described previously will be difficult. Application of pressure to the cartilaginous auricle needs custom-made devices. At this point, a pressure sore caused by a device applied to the ear is the most important problem. To prevent the ear from developing a pressure sore, the device should press to whole area homogeneously. For this reason, the device applied for pressure therapy to the ear must be custom made.

Surgical treatment of urologic complications after renal transplantation

AIM

The incidence of urologic complications after renal transplantation has been reported to be between 2.5% and 27%. The aim of this study was to evaluate urologic complications of and their surgical treatment in our series of renal transplantations.

MATERIALS AND METHODS

We retrospectively evaluated urologic complications among 395 renal transplant recipients in our institute.

RESULTS

The urologic complications were ureteral leakage (n = 8), stricture of ureteral anastomosis (n = 3), hydronephrosis secondary to stone (n = 2) and bladder outlet obstruction (n = 2), recurrent urinary infection because of vesicoureteral reflux to native kidney (n = 2), renal tumor in native kidney (n = 1), hydroceles (n = 3), technical complications (n = 2), and clot retention (n = 1).

CONCLUSION

Major urologic complications following renal transplantation are ureteral leakage and stricture resulting from disrupture of the distal ureteral blood supply during the donor operation. Extravesical ureteroneocystostomy over a JJ stent seems feasible to minimize urologic complication. Early diagnosis and endourologic techniques are the mainstays of treatment.

Quality of life analysis of renal donors

OBJECTIVE

The aim of this study was to investigate the quality of life of renal donors during long-term follow-up.

PATIENTS AND METHODS

The short form health survey (SF-36) questionnaire was compared between renal donors and the general population. We evaluated the relationship to postoperative complications and preoperative information with the quality of life.

RESULTS

Fifty renal donors of mean age 55.8 +/- 12 years (range, 29-70 years) had a mean follow-up of 55.1 +/- 47.2 months (range, 12-168 months). Complications after donor nephrectomy were related with physical function loss (r = -.397; P < .05) and vitality (r = -.463; P = .01). Renal donor candidates who did not have satisfactory information before the operation experienced difficulty with decision making (r = -.555; P = .0001). Physical function, limitation of physical role and limitation of emotional role were comparable to the general population. Pain scale was worse among donors compared with the general population (P = .001). Educational status of renal donors was related to the pain scale and vitality (r = .369; P < .05 and r = .523; P < .05, respectively). General health perception, vitality, mental health, and social functioning were worse compared with the general population (P = .0001, P = .002, P = .0001, and P = .001, respectively). Health problems occurring after donation were related to negation of interfamily relations (r = .695; P = .0001).

CONCLUSIONS

Reducing complications after nephrectomy will directly increase the quality of the donor's life. Informing renal donor candidates and their families about the postoperative course with consideration of the candidate's and his or her family's educational status is a sociological approach which helps to increase the donor's quality of life. In addition to good patient selection/preparation, meticulous surgery, and follow-up.

Medical risk analysis of renal transplant donors

AIM

The aim of this study was to evaluate the long-term medical risks of living-related donors in our center.

PATIENTS AND METHODS

185 living-related donors participated in the study. The factors assessed were creatinine clearance rate (CrCl), serum creatinine (SCr), BUN, hematocrit levels, proteinuria, microalbuminuria and hypertension rates, and renal parenchyma thickness and kidney dimensions predonation as well as at the last follow-up. In addition, we examined postoperative complications. A lombotomy incision was the choice for donor nephrectomy procedure routinely.

RESULTS

The mean length of hospital stay after donor nephrectomy was 3.2 +/- 0.6 days (range, 2-5 days). Seven donors readmitted during the first month after operation with surgical site infection were treated successfully. Four donors were reoperated for incisional hernia repairs and discharged without complication. The mean follow-up period was 61.6 +/- 50.4 months (range, 2-180 months). Mean ages of the donors at operation and at the last follow-up were 50.9 +/- 12.7 years (range, 20-81 years) and 56.5 +/- 11.9 years (range, 29-77 years), respectively. The male-to-female ratio was 0.69. Mean SCr levels and CrCl rates predonation and at the last follow-up were 0.83 +/- 0.22 mg/dL versus 1.1 +/- 0.2 mg/dL (P < .001), and 103.9 +/- 28.8 mL/min versus 88.3 +/- 25.9 mL/min (P = .03), respectively. SCr levels were within normal limits in all donors at predonation and at the last follow-up. At the last follow-up, CrCl was also within expected normal limits in all donors. Hypertension was detected in 13 donors. Mean predonation and at the last follow-up renal parenchymal thickness, BUN, and hematocrit levels were similar. Kidney dimensions were significantly different at the last follow-up after donation (P = .001). Eleven donors displayed proteinuria and 19 had microalbuminuria at the last follow-up, which had been negative for all donors predonation. There were seven surgical site infections and 4 incisional herniae.

CONCLUSION

Donor nephrectomy was performed with low surgical morbidity and comparable results of clinical and laboratory data to the age-matched general population.

Analysis of L-myc gene polymorphism in patients with renal failure outcome to renal transplant

BACKGROUND

Abnormalities of cell numbers and apoptosis have been observed in renal failure. As uncontrolled expression of c-myc is known to induce apoptosis, we thought that polymorphism in the other myc gene, L-myc gene, which is structually similar to c-myc and reported to be expressed in the kidney, may have a role in the induction of apoptosis and thus have role in chronic renal failure. The aim of this study was to investigate the relationship between the distribution of L-myc genotypes and renal failure.

METHODS

In the present study we examined 101 chronic renal failure patients who had either live or cadaveric renal transplants and 105 healthy individuals, for L-myc gene polymorphism by polymerase chain reactions and restriction fragment length polymorphism techniques.

RESULTS

Among our patient group, the distribution of the LL, LS, and SS genotypes was 24% (n=25), 71% (n=71), and 5% (n=5), respectively, versus 41% (n=43), 47% (n=49), and 12% (n=13) in our control group. The distribution of genotypes was significantly different between our patients and the control group (chi2=12.281; P=.002). The frequency of the S allele was significantly higher in the patient group (chi2=6.122; P=.013).

CONCLUSION

Our study showed that having an S allele in the L-myc gene may increase the risk of renal failure.

The effect of HBsAg-positivity of kidney donors on long-term patient and graft outcome

The number of patients on the kidney waiting list is increasing, creating a shortage of donor organs. To solve this problem, there is an interest in transplanting organs formerly considered marginal or undesirable. We performed seven (four living related, three cadaveric) kidney transplants from hepatitis B surface antigen (HBsAg)-positive donors. Hepatitis B e antigen (HBeAg) and hepatitis B virus (HBV) DNA were negative in the living donors and were unknown in cadaveric donors. Liver function tests were in the normal range in all of the donors. All of the recipients were HBsAg-negative and hepatitis B surface antibody (anti-HBs)-positive. Recipients receiving kidneys from cadaveric donors were given prophylactic lamivudine treatment postoperatively. Anti-HBs remained positive throughout the follow-up period in all but one patient with a cadaveric graft. None of the patients receiving a kidney from an HBsAg-positive donor developed clinical HBV infection in a mean follow-up period of 42.6 +/- 36.8 months (range: 16 to 121 months, median 30 months). Liver function tests remained in the normal ranges in all patients. All the grafts are still functioning with a mean serum creatinine level of 1.6 +/- 0.85 mg/dL. In conclusion, transplants from HBsAg-positive and HBeAg-/HBV DNA-negative donors seem to carry no risk to the recipients who are immune to HBV. Even cadaveric donors with HBsAg-positivity and unknown HBeAg/HBV DNA status can be used with caution in selected recipients without significantly affecting graft and patient outcome.

Pediatric Renal Transplantation: Clinical Analysis of 28 Cases

We performed an outcome analysis of 28 pediatric renal transplant recipients whose mean age at transplantation was 15.2 +/- 2 years (range: 11 to 17 years) and the M/F ratio, 0.75. Four patients received cadaveric grafts. One patient needed retransplantation due to primary nonfunction. Mean HLA match was 3.6 (range: 3 to 5). Immunosuppression was cyclosporine (n = 13) or tacrolimus (n = 11) or sirolimus (n = 4), as well as steroids and azathioprine or mycophenolate mofetil. Delayed graft function occurred in four patients. The main complications were arterial hypertension (n = 11), anemia (n = 4), urinary tract infection (n = 10), hypercholesterolemia (n = 7), and cytomegalovirus infection (n = 1). An acute rejection episode (ARE) occurred in four patients. ARE and hypertension rates were similar between the immunosuppressive drug groups. All the patients with graft failure were on cyclosporine (P = .03). Hemodialysis and peritoneal dialysis (median duration: 6 months) were performed preoperatively in 25 and 3 patients, respectively. The length of pretransplant dialysis was longer among patients with graft failure (P > .05). Noncompliance (10.7%) resulted in an ARE in one patient and graft loss in two patients. One patient died with a functioning graft. Primary disease recurred in one patient. The median follow-up period was 44 months (range: 6 to 157 months). Mean serum creatinine level was 1.35 +/- 0.74 mg/dL at the last follow-up. One- and 3-year graft survival rates were 92% and 86%, respectively, and patient survival was 100%, each. Seventeen patients (60.7%) continued their education after the transplantation; six started working. Successful transplantation in the pediatric age group together with intensive rehabilitation posttransplantation are important to make these children productive individuals to the society.

Kaposi's sarcoma in renal transplant patients: predisposing factors and prognosis

Among 772 kidney transplant recipients in two centers 25 patients developed Kaposi's sarcoma (KS) (3.2%). The twenty-two of 25 recipients with regular follow-up records were compared for predisposing factors with another group of 22 renal transplant recipients. All patients received cyclosporine (CsA), azathioprine, or mycophenolate mofetil and steroids; patients who received cadaver donor organs additionally received antilymphocyte globulin for induction. KS was diagnosed at a mean of 25.8 months after transplantation. The male to female ratio; mean age; mean follow-up period; hepatitis B, hepatitis C, cytomegalovirus status; and other infection rates were similar in the two groups. Some HLA-DR antigens were detected only in patients with KS. All patients had mucocutaneous involvement, which was multiple in 54.5%. Visceral involvement, and lymph node involvement, or both was detected in seven patients. First-line treatment was to stop CsA and reduce the doses of the other drugs. Three patients underwent additional surgical excision. Fourteen (63.6%) patients experienced complete remissions, including six who required additional chemotherapy or radiotherapy after incomplete or lack of responses to first-line treatment. Two patients died with functioning grafts due to generalized KS. Seven patients returned to hemodialysis at a mean of 36 months after the diagnosis of KS. No significant predisposing factor was observed other than the prevalence of specific HLA-DR antigens. Chemotherapy or radiotherapy should be initiated for patients with multiple, diffuse, and rapidly progressive lesions or organ dysfunction in addition to withdrawal of CsA and tapering of other drugs. Generalized KS displays the poorest prognosis.

Blood Pressure and Graft Outcome in Renal Transplantation

To investigate the effects of blood pressure (BP) on kidney function, we reviewed 116 patients who had a median follow-up of 40.5 months. Systolic and diastolic hypertension (HTN) at month 6 resulted in significantly higher serum creatinine (SCr) levels at 1 year, compared with patients with normal BP, namely, 2.2 versus 1.4 mg/dL (P = .0001) and 1.87 versus 1.5 mg/dL (P = .04), respectively. Mean systolic and diastolic BP at the end of 1 and 6 months were significantly higher among patients who had returned to hemodialysis or who had an SCr > or =2 mg/dL at their last follow-up. Mean age, mean donor age, donor type, and sex had no significant effect on graft function. Patients receiving Rapamune-based treatment (n = 9) had no graft failure; graft outcomes were similar between cyclosporine-based and tacrolimus-based immunosuppression therapy. Patients with biopsy-proved acute rejection showed significantly lower graft survival. By multivariate analysis, systolic HTN at the end of 1 month (P = .006) and 6 months (P = .01), and diastolic HTN at the end of 6 months (P = .04) were independent risk factors for graft outcome. Actuarial 5-year graft survival was 95%, versus 76% in patients with normal BP versus systolic HTN at 1 month, respectively (P = .02). A significant difference in 5-year graft survival was observed between patients with normal diastolic BP and diastolic HTN at 6 months (95% versus 67%, respectively; P = .001). Since systolic and diastolic BP at different times before and after transplantation correlate with graft function, more attention should be paid to maintain normal BP in patients with renal transplants.