MANAGEMENT PRINCIPLES OF INCIDENTAL THYROID 18F-FDG UPTAKE IDENTIFIED ON 18F-FDG PET/CT IMAGING

PURPOSE

The purpose of this study is to determine the clinical significance of incidental thyroid 18F-FDG PET/CT uptake in oncology patients with the focus achieving the most appropriate management of this challenging situation.

MATERIALS AND METHOD

Two thousand five hundred and eighty 18F-FDG PET/CT studies performed at our institute in the past 4 years were retrospectively reviewed. Patients with incidental FDG uptake in the thyroid gland were further analysed.

RESULTS

The prevalence of incidental FDG uptake in thyroid gland was 7.6% (129 patients). 26 patients (20.1%) had diffuse 18F-FDG PET/CT uptake, 103 patients (79.1%) had nodular uptake in thyroid gland. All diffuse uptake patients who were further examined diagnosed to be a benign condition. 53 patients in the nodular uptake group were further examined and the final histopathology examinations revealed an 18.8% malignancy rate. SUV max values ranged from 2 to 21.8 with a significant highness in malignant lesions.

CONCLUSION

18F-FDG PET/CT uptake in the thyroid gland may be diffuse or nodular. Diffuse uptake needs no further examination as it usually accompanied by benign thyroid disorders. Patients with nodular uptake whose general condition is good should be further examined due to high rates of malignancy.

Timing of laparoscopic cholecystectomy in acute cholecystitis

Background

Timing of laparoscopic cholecystectomy (LC) in acute cholecystitis (AC) is still debated.

Aims

The aim of this study was to investigate the effect of timing on operative results; from the first appearance of symptoms to the operation.

Methods

The study included 57 sequential patients operated laparoscopically for AC. Patients operated within the first 3 days of admission (Group 1), those operated between 4^th and 7^th days (Group 2) and those operated after 7^th day (Group 3) were evaluated and compared with respect to demographics, time from admission to operation, duration of operation, adhesion score, complications, conversion rates, duration of hospital stay, morbidity and mortality rates, bile culture results, and histopathological evaluation.

Results

A total of 63% of the patients were female and 21 (37%) were male. The mean age was 48 years (range, 21-74). There was no significant difference among the groups with respect to demographics (P > 0.05, for each). The duration of operation was significantly shorter in Group 1 than both Groups 2 and 3 (P < 0.05 and P < 0.001, respectively). Duration of operation was also significantly shorter in Group 2 than Group 3 (P < 0.001). Group 1 had significantly fewer adhesions compared to Group 2 and Group 3 (P < 0.05 and P < 0.001, respectively), and no significant difference was found between Group 2 and Group 3 (P > 0.05). Duration of hospital stay was significantly shorter in Group 1 compared to Group 2 and Group 3 (P < 0.001) and also was significantly shorter in Group 2 than Group 3 (P < 0.05). Group 1 had significantly lower rate of culture proliferation than Group 3 (P < 0.001), whereas no significant differences were evident in other inter-group analyses (P > 0.05, for each).

Conclusion

LC can safely be performed within 7 days of admission in cases of AC.

Lymphocyte-C-reactive protein ratio: a putative predictive factor for intestinal ischemia in strangulated abdominal wall hernias

PURPOSE

The purpose of this study was to investigate whether it is possible to estimate systemic inflammation and intestinal ischemia in incarcerated hernias using the lymphocyte-C-reactive protein ratio (LCR).

METHODS

A total of 116 patients who underwent an emergency operation due to incarcerated abdominal wall hernia were investigated retrospectively. The patients with incarcerated hernias were divided into two groups: those who did not undergo intestinal resection and those who underwent intestinal resection due to strangulation. The two groups were analyzed based on sex, surgical operation (open, laparoscopic), length of stay, complications and mortality rates as well as preoperative period laboratory analyses, such as white blood cell, neutrophil, thrombocyte, and lymphocyte counts and C-reactive protein (CRP), neutrophil-lymphocyte ratio (NLR) and LCR values.

RESULTS

Twenty-five patients (21.6%) underwent intestinal resection due to strangulated hernia. Neutrophil count, lymphocyte count, CRP, platelet count, NLR, and LCR were significantly different in the strangulated hernia group. Receiver operating characteristic (ROC) analysis results showed that an LCR level below 0.02 had 80% sensitivity (58-92%) and 80.2% specificity (70-87%) for the diagnosis of strangulation.

CONCLUSION

A low preoperative LCR level in incarcerated hernias could be used as a bioindicator that helps to estimate the intestinal ischemia.

A new prognostic strategy for gastric carcinoma: albumin level and metastatic lymph node ratio

AIM

We evaluated the prognostic significance of preoperative serum albumin value and metastatic lymph node ratio for gastric cancer patients.

METHODS

We studied patients diagnosed with gastric carcinoma in the first Department of Surgery, Bezmialem Vakif Gureba Training and Research Hospital between January 2004 and December 2010; the patients were studied retrospectively.

RESULTS

A total of 67 patients with a mean age of 58.7 ± 11.4 years were included in the study. The majority of patients were male (N.=53 male; N.=14 female). Most patients were in an advanced stage of the disease (stage III-IV) on admission (67.2%). We classified patients according to albumin value as "normal" Group 1 (83%) and "hypoalbuminemic" Group 2 (17%). With albumin, age, resection type, perineural invasion, and ratio of metastatic lymph nodes, T and TNM stages were significant predictors of cancer-specific survival.

CONCLUSION

As a result, irrespective of mechanism, pre-operative evaluations of albumin and metastatic lymph node ratio should be performed to stratify the patients for risk analysis and prognosis. A level less than 3.5 g/dL is a negative prognostic factor for resectable gastric cancers.

"Diagnostic value of MRCP in biliary pancreatitis: result of long-term follow-up"

AIM

Magnetic resonance cholangiopancreatography (MRCP) has increasingly been used to evaluate the common bile duct. This study was to determine the role of MRCP instead of endoscopic retrograde cholangiopancreatography (ERCP) in the management of patients with acute biliary pancreatitis.

METHODS

A total of 81 patients with mild or moderate biliary pancreatitis who underwent MRCP and were treated in our department with selective ERCP between May 2001 and July 2007 were entered into a prospective database.

RESULTS

MRCP was considered abnormal in 13 patients. Ten patients underwent ERCP. Three patients did not undergo ERCP due to protocol violations. In nine patients, stone extraction was performed. The remaining patient who had dilatation of the CBD underwent ES. The false positive rate of MRCP was 10%. The median follow-up of overall patients was 36 months (range 23-99 months). The patients with normal MRCP had a median follow-up of 39.5 months (range 23-99 months). During the follow-up period in the normal MRCP group, five patients were diagnosed with recurrent biliary pancreatitis, of which three underwent ERCP (7.4%). There was no disease-related mortality during this period.

CONCLUSION

In conclusion, the use of MRCP in acute biliary pancreatitis is safe and may be recommended as a tool to aid in the selective use of ERCP.

Dieulafoy lesion in the stomach

Dieulafoy disease is an uncommon cause of gastrointestinal system bleeding. Although the exact cause is not known, it is characterized by bleeding from abnormal submucosal vessels. There are many methods for diagnosis and treatment. In this case, a patient with a long-time undiagnosed stomach Dieulafoy lesion had a surgical resection. During the postoperative period the patient was discharged without any complication.

Risk factors of morbidity and mortality in patients with perforated peptic ulcer

PURPOSE

Peptic ulcer perforation is a serious problem that leads to high complication and mortality rates. The aim of this prospective clinical study was to evaluate complications and possible risk factors for peri-operative morbidity and mortality in patients with perforated peptic ulcer (PPU).

MATERIAL AND METHODS

Ninety-seven patients hospitalized for PPU at the Department of Surgery, Vakif Gureba Training and Research Hospital, between March 1998 and December 2004 were analysed.

RESULTS

The mean age of patients was 38.6 years. Ten patients had 19 co-morbidities. The mean hospitalisation time was 7.1 days. Twenty-one complications in 15 patients occurred. Overall morbidity and mortality rates were 15.5% and 5.2% respectively. Multivariate logistic regression analysis of 97 patients revealed that age (p < 0.006) and late admission (p < 0.001) were linked to morbidity. The mortality rate tended to be associated with advanced age, therapeutic delay and co-morbidities.

CONCLUSIONS

Increased patients' age and the therapeutic delay, predicted outcome after surgical treatment of PPU. Morbidity and mortality could be reduced by avoiding delays in diagnosis and treatment, especially in older patients, and by instituting proper treatment of any coexisting medical illness.

Idiopathic abdominal cocoon: report of a case

The abdominal cocoon is a rare disease in which there is total or partial encapsulation of the small bowel by a fibrous membrane. A correct diagnosis is not often made pre-operatively. Awareness of this rare cause of surgical emergency may prevent delay in treatment and avoid unnecessary procedures for the patient, such as bowel resection. We report a patient diagnosed with abdominal cocoon who was subsequently treated.

Endoscopic stenting for selected cases of biliary fistula after hepatic hydatid surgery

BACKGROUND

Biliary fistula develops in 4%-28% of patients after hepatic hydatid disease (HHD) surgery. Although endoscopic retrograde cholangiopancreatography (ERCP) and endoscopic sphincterotomy (ES) are helpful in the treatment of this complication, persistent fistulas may occur. We therefore conducted a study to evaluate the efficacy of endoscopic biliary stenting in the treatment of biliary fistulas after HHD.

METHODS

In this study, 84 patients who underwent ERCP for postoperative biliary fistula due to HHD were evaluated. Group I included 70 patients treated with only ES, and group II included 14 patients who underwent biliary stenting as their initial treatment. Demographic data, complications, the results of treatment and the reasons for the failure were compared between two groups.

RESULTS

Ninety-five ERCPs were performed. In 63 patients, biliary fistulas were successfully treated with only ERCP and ES. However, 7 patients underwent repeat ERCP and stent placement because of persistent fistula. Biliary stenting was initially performed in 14 patients. The average time for closure of the fistula was 14 +/- 10 days and 7 +/- 3 days in group I (7 patients with repeat ERCP were excluded) and group II, respectively (p = 0.007). There was no statistically significant difference in the complication rates between the groups.

CONCLUSIONS

Although ES is effective in the treatment of biliary fistula after HHD surgery, endoscopic biliary stenting may be considered as the initial procedure in patients with biliary stricture, incomplete clearance of hydatid material in the bile duct, and persisting biliary fistulas after treatment with ERCP and ES.

Femoral hernia: a review of 83 cases

We evaluate the factors that affect morbidity and mortality in patients who underwent surgery due to femoral hernia. The medical records of 83 patients who underwent femoral hernia repair between January 1996 and June 2004 were retrospectively analyzed. The femoral hernias were repaired either with McVay or mesh plug hernioplasty. Sex, age, surgical repair technique, presence of incarceration/strangulation, incarcerated/strangulated organs, postoperative complications, duration of hospitalization, recurrence rate, and factors that affect mortality and morbidity were studied. There were 83 patients with femoral hernia in our study. Patients' age ranged from 10 to 75 years (mean age was 46.84) with a predominance of female (71%). Thirty-six patients (40%) underwent emergency surgery with the diagnosis of strangulation or incarceration of femoral hernia. Seventeen patients had strangulation and underwent resection; eleven of these patients had omentum in the hernial sac, whereas six patients had intestines. Four of these patients underwent laparotomy. The remaining 19 patients had incarceration and underwent simple reduction of hernial sac content without resection. Forty-seven (60%) patients underwent elective surgery. McVay technique was used for 79 patients, while the other four patients were treated with mesh-plug. Twelve patients (15%) developed a variety of complications (nine patients (25%) in emergency, three patients (6%) in elective group). There was one mortality. Recurrences occurred in two patients. Femoral hernia is an important surgical pathology with high rates of incarceration/strangulation and intestinal resection. Emergency surgery can increase morbidity and mortality especially in the elderly. Early elective surgery may reduce complication.

Serum leptin levels in patients with liver cirrhosis and chronic viral hepatitis

BACKGROUND

The aim of the present study was to investigate serum leptin levels in relation to anthropometric features in patients with liver cirrhosis (LC) and chronic viral hepatitis (CVH), and to determine the effect of the severity and aetiology of the LC on serum leptin levels.

METHODS

Forty-nine patients with LC, 32 patients with CVH and 69 control subjects were age, body mass index (BMI) and sex-matched and included in the study. Plasma glucose, serum leptin and insulin levels were determined. Insulin resistance was assessed using homoeostasis model assessment (HOMA). Body composition was estimated by skinfold thickness.

RESULTS

Female patients with Child-A LC had higher levels of leptin, and female and male patients with Child-A LC had higher absolute leptin (leptin/BFM) levels compared to patients with Child-C LC and control subjects. Serum leptin levels of the patients with alcohol LC were higher than the control subjects, but the absolute leptin levels were comparable. When alcoholic and post-viral hepatitis cirrhotic patients were compared with each other on an aetiologic basis, there was no significant difference between them in leptin and absolute leptin levels. There were significant correlations between leptin and BMI, body fat percentage (BFP), BFM (body fat mass) in all three groups in both sexes.

CONCLUSIONS

These data suggest that the physiologic correlations among serum leptin level, sex, BMI and BFM were well preserved in patients with chronic liver disease. Patients with alcohol LC had higher leptin levels. In early stages of liver disease, leptin levels and absolute leptin levels are higher than in normal subjects. However, in advanced stages of the disease the significant decline in leptin levels and similar levels of leptin expressed in relation to BFM compared to control subjects predominantly represent the expression of fat mass.

Serum concentrations of insulin-like growth factor-I and insulin-like growth factor binding protein-3 in patients with chronic hepatitis

BACKGROUND

Insulin-like growth factor-I is a liver-derived humoral factor, which has important anabolic and metabolic actions and is predominantly bound by insulin-like growth factor binding protein-3. Low serum concentrations of both insulin-like growth factor-I and insulin-like growth factor binding protein-3 have been reported in patients with chronic liver disease, especially cirrhosis, but their conditions in chronic hepatitis are uncertain. The aim of this study was to evaluate the effect of chronic hepatitis on serum concentrations of insulin-like growth factor-I and insulin-like growth factor binding protein-3 and their association with hepatic inflammation activity and fibrosis.

METHODS

Serum insulin-like growth factor-I and insulin-like growth factor binding protein-3 were measured by RIA (ng/ml) in 17 patients with mild to severe chronic viral hepatitis (12 chronic hepatitis C, 5 chronic hepatitis B) and 16 healthy subjects. The hepatic inflammation activity and the severity of fibrosis were evaluated using Desmet classification.

RESULTS

Both insulin-like growth factor-I and insulin-like growth factor binding protein-3 levels did not correlate with inflammation activity, fibrosis or transaminase levels. In the chronic hepatitis group, insulin-like growth factor-I levels were significantly higher than the control group (mean, 263.8 +/- 27.33 versus 127.14 +/- 10.83 ng/ml, P < 0.001, respectively), whereas insulin-like growth factor binding protein-3 levels were significantly lower when compared with the controls (1643.47 +/- 60.68 versus 2728.87 +/- 284.61 ng/ml, P < 0.05, respectively).

CONCLUSIONS

These results suggest that the concomitant states of serum insulin-like growth factor-I and insulin-like growth factor binding protein-3 levels in patients with chronic hepatitis may be different from cirrhotic patients and high serum IGF-I levels may be a specific finding of the stage of chronic hepatitis before developing cirrhosis.

Epstein-Barr virus infection and mitogen stimulation of normal B cells induces wild-type p53 without subsequent growth arrest or apoptosis

Infection of human B lymphocytes with Epstein-Barr virus (EBV) in vitro induces a G0 to G1 transition followed by DNA synthesis and cell division. The virus activation of the cell cycle closely mimics the antigen-dependent normal B cell activation pathway. Infected B cells undergo blast transformation followed by the emergence of immortalized lymphoblastoid cell lines. Numerous cellular proteins are switched on in the infected cells, including p53. In view of the frequent association of wild-type p53 (wtp53) expression with growth arrest and apoptosis, p53 expression, cell viability (absence of apoptosis) and cell cycle progression at the single cell level during the first week after EBV infection were assessed. The rate of EBV infection was scored by EBNA-5 staining between 20 and 72 h after infection and varied between 20 and 25% of the cell population. All EBNA-5-positive blasts were p53-positive as well. Double staining for p53 and for DNA ends (TUNEL) revealed that p53-positivity and apoptosis were mutually exclusive. Quantification of the DNA content by Hoechst staining and computer-assisted image analysis showed that a fraction of the p53-positive blasts had a DNA content higher than 2N, indicating entry into the S/G2 phases. Double p53 and BrdU staining of the cells, pulse-labelled with BrdU, revealed that 65% of the p53-positive blasts were in S phase 3 days after infection. Similarly, B cell activation by CD40L and IL-4 induced p53 expression without any adverse effect on cell cycle progression. Therefore, the phenomenon is not EBV-specific but correlates with immunoblast activation.

Symptomatic hypocalcemia in a patient with latent hypoparathyroidism and breast carcinoma with bone metastasis following administration of pamidronate

Pamidronate is an effective drug used not only in patients with tumor-associated hypercalcemia, but also in normocalcemic patients with metastatic bone disease to relieve pains. We describe a 39-year-old normocalcemic patient with subclinical hypoparathyroidism and bone metastasis due to breast carcinoma. Following parenteral administration of 60 mg pamidronate, the corrected serum level of calcium decreased from 2.12 mmol/l (=8.9 mg/dl) to 1.42 mmol/l (5.7 mg/dl), accompanied with carpal pedal spasm. The present case indicates that the hypocalcemia due to latent hypoparathyroidism was compensated by extensive osteolysis due to bone metastasis, and that overt hypocalcemia may develop after intravenous administration of pamidronate in such a patient.

p16/INK4a and p15/INK4b gene methylation and absence of p16/INK4a mRNA and protein expression in Burkitt's lymphoma

The fact that the p16/INK4a and p15/INK4b genes are frequently inactivated in human malignancies and that p16/INK4a null mice spontaneously develop B-cell lymphomas prompted us to examine the status of both genes in Burkitt's Lymphoma (BL). We found a low frequency of p16/INK4a and p15/INK4b deletions and mutations in BL cell lines and biopsies. However, p16/INK4a exon 1 was methylated in 17 out of 19 BL lines (89.5%) and in 8 out of 19 BL biopsies (42%) analyzed. p15/INK4b Exon 1 was also methylated, although at a lower frequency. p16/INK4a mRNA was readily detected in BL lines carrying unmethylated p16/INK4a, but not in those carrying methylated p16/INK4a. No p16/INK4a protein was detected in any of the BL lines and biopsies examined. In contrast, only one out of seven lymphoblastoid cell lines (LCLs) examined was methylated in p16/INK4a exon 1, and three out of the six LCLs with unmethylated p16/INK4a expressed detectable levels of p16/INK4a protein. Thus, the frequent p16/INK4a methylation in BL lines correlates with downregulation of p16/INK4a expression, suggesting that exon 1 methylation is responsible for silencing the p16/INK4a gene in BL.

Wig-1, a new p53-induced gene encoding a zinc finger protein

Wild type p53 expressed from a temperature-sensitive (ts p53) construct induces both G1 cell cycle arrest and apoptosis in the p53-negative J3D mouse T lymphoma line (Wang et al., 1995). Using differential display analysis, we have identified one new p53-induced gene, wig-1 (for wild type p53-induced gene 1), whose 7.6 kb and 2.2 kb transcripts are upregulated in ts p53-transfected J3D cells following induction of wild type p53 expression by temperature shift to 32 degrees C. The wig-1 transcripts were also induced in irradiated NIH3T3 and p21-/- fibroblasts but not in irradiated p53-/- fibroblasts. Whole body gamma irradiation caused induction of both wig-1 transcripts in mouse brain, testis, kidney, spleen and lung. A basal wig-1 expression was detected in brain, testis and kidney. The WIG-1 protein contains three zinc finger motifs and a putative nuclear localization signal.

Restoration of the growth suppression function of mutant p53 by a synthetic peptide derived from the p53 C-terminal domain

We demonstrate here that synthetic 22-mer peptide 46, corresponding to the carboxy-terminal amino acid residues 361-382 of p53, can activate specific DNA binding of wild-type p53 in vitro and can restore the transcriptional transactivating function of at least some mutant p53 proteins in living cells. Introduction of peptide 46 in Saos-2 cells carrying a Tet-regulatable His-273 mutant p53 construct caused growth inhibition and apoptosis in the presence of mutant p53 but not in its absence, confirming that the effect of the peptide is mediated by reactivation of mutant p53. Moreover, peptide 46 caused apoptosis in mutant as well as wild-type p53-carrying human tumor cell lines of different origin, whereas p53 null tumor cells were not affected. These findings raise possibilities for developing drugs that restore the tumor suppressor function of mutant p53 proteins, thus selectively eliminating tumor cells.

Role of p53 mutation in polyomavirus-induced tumorigenesis

Small DNA tumour viruses, such as simian virus 40 (SV40), papilloma viruses and adenoviruses, encode proteins that form complexes with and inactivate the p53 and retinoblastoma (RB) proteins. This convergent evolution reflects the common need of these viruses to inactivate these two important regulators of cell cycle progression and cell survival. Polyomavirus, a close relative of SV40, is different. Its large T protein complexes only with RB, not with p53. We have examined whether this is compensated by the frequent appearance of p53 mutations in polyomavirus-induced tumours. We tested the p53 status of 15 polyomavirus-induced sarcomas. Two sarcomas were p53-negative while six carried mutant p53. Another six sarcomas expressed low levels of wild-type p53. One tumour expressed high levels of wild-type p53 protein as shown by DNA sequencing and immunofluorescence staining. MDM2 amplification was not detected in any of the tumours, but Northern blotting showed that MDM2 was overexpressed in at least two tumours that expressed wild-type p53 and in one tumour that expressed both wild-type and mutant p53. Treatment with the DNA-damaging agent mitomycin C caused p53 protein accumulation followed by induction of MDM2 and WAF1/p21 mRNA in four of the tumours expressing wild-type p53, indicating that p53-mediated transcriptional activation was unaltered in these tumours. However, p53-mediated transactivation of WAF1/p21 was impaired in the wild-type p53-expressing tumours that expressed elevated levels of MDM2. These results demonstrate that p53 mutation and inactivation are frequently but not invariably involved in polyomavirus-induced tumorigenesis.

Wild-type p53-induced apoptosis in a Burkitt lymphoma cell line is inhibited by interferon gamma

The tumor suppressor p53 plays a central role in negative growth control, including growth arrest and apoptosis. Interferons (IFNs) are capable of modulating a variety of cellular responses, including apoptosis. In this study, we have evaluated the influence of gamma- and alpha-interferon (IFN) on wild-type (wt) p53-induced apoptosis using a Burkitt lymphoma cell line, BL41, transfected with a temperature-sensitive p53 construct, gamma-IFN, but not alpha-IFN, was found to protect cells from wt p53-induced apoptosis. The gamma-IFN-dependent protection was due neither to down-regulation of p53, nor to the p53-induced genes, p21 (WAF-1) and bax, nor to up-regulation of bcl-2 or bcl-xL. Expression of the proto-oncogene c-myc, implicated in the control of both proliferation and apoptosis, was not affected by gamma-IFN. We conclude that gamma-IFN can suppress p53-induced apoptosis, and that the cytokine microenvironment may be decisive in the cellular response to wt p53 expression.

Abrogation of p53-induced G1 arrest by the HPV 16 E7 protein does not inhibit p53-induced apoptosis

Wild type (wt) p53 expressed from a temperature-sensitive construct (ts p53) can induce both G1 cell cycle arrest and apoptosis in the p53-negative J3D mouse T lymphoma line (Wang et al, 1995). The human papillomavirus (HPV) 16 E7 protein has been shown to prevent p53-induced G1 cell cycle arrest following DNA damage. We asked whether inhibition of p53-induced G1 arrest by overexpression of the HPV16 E7 protein in the ts p53-transfected J3D cells would interfere with p53-induced apoptosis. Whereas a majority of the ts p53-expressing J3D cells were arrested in the G1 phase 22 h after induction of wt p53 by temperature shift to 32 degrees C, the E7/ts p53-expressing cells showed only a minor increase in the number of cells in G1 at this time point. In addition, the E7/ts p53-expressing cells showed a much less dramatic reduction in number of cells in S phase than the ts p53-expressing cells. This demonstrates that E7 at least partially rescues the cells from p53-induced G1 arrest. In contrast, overexpression of HPV16 E7 did not have any effect on the kinetics nor the frequency of p53-triggered apoptotic death, as shown by FACS analysis, trypan blue exclusion, and DNA fragmentation analysis. These findings support the notion that p53-induced G1 arrest and p53-induced apoptosis are two separate independent pathways.

Frequent expression of Bcl-2 in renal-cell carcinomas carrying wild-type p53

The p53 tumor-suppressor gene is the most commonly mutated gene in cancer. However, p53 gene alterations are infrequent in renal-cell cancer (RCC). Bcl-2 has been shown to inhibit apoptosis triggered by wild-type p53 and an inverse correlation between Bcl-2 expression and p53 mutation has been observed in breast cancer and glioma. To characterize the expression of bcl-2 in RCC and its relationship to the p53 status, we analyzed 25 RCCs by immunohistochemistry for Bcl-2 and p53, Southern hybridization for bcl-2, and PCR-SSCP and sequencing for p53. Positive Bcl-2 staining was detected in 17 of 25 RCCs, whereas positive p53 staining was seen in only 1. Amplification of bcl-2 or p53 mutation was not detected in any of the tumors. Bcl-2 protein was expressed in all 7 RCC cell lines examined. Only one of the 7 lines had p53 mutation. These results suggest that overexpression of bcl-2, rather than p53 mutation, may prevent apoptosis during RCC development.

The EBV-encoded LMP1 protein inhibits p53-triggered apoptosis but not growth arrest

We have previously shown that exogenous wild type p53 induces apoptosis in the Burkitt lymphoma line BL41 that carries endogenous mutant p53, using a temperature sensitive p53 construct expressed as mutant p53 at 37 degrees C and wild type p53 at 32 degrees C (Ramqvist et al., Oncogene, 8, 1495-1500, 1993). We also found that wild type p53-induced apoptosis is blocked by bcl-2 in a mouse T lymphoma line (Wang et al., Oncogene, 8, 3427-3431, 1993) The Epstein-Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) can protect Burkitt lymphoma cells from apoptosis induced by low serum. In order to test if LMP1 can block p53-triggered apoptosis, we infected BL41 cells expressing the ts p53 construct with an LMP1-carrying retrovirus. The LMP1-expressing BL41-ts p53 cells were arrested in G1 upon induction of wild type p53 expression at 32 degrees C, but did not enter apoptosis as shown by the absence of positive TUNEL staining. WAF1/p21 mRNA was induced at 32 degrees C in both the ts p53-expressing and ts p53/LMP1-expressing BL41 cells. Thus, LMP1 prevents p53-induced apoptosis but does not interfere with induction of WAF1/p21. The LMP1-infected cells expressed elevated bcl-2 protein levels. Therefore, our data suggest that LMP1 blocks p53-triggered apoptosis but not G1 arrest by upregulating bcl-2 expression.

bcl-2 inhibits wild-type p53-triggered apoptosis but not G1 cell cycle arrest and transactivation of WAF1 and bax

We have earlier shown that wild-type (wt) p53 expressed from a temperature-sensitive construct (ts p53) triggers apoptosis in the v-myc retrovirus-induced, p53-negative T-cell lymphoma line J3D (Y. Wang et al., Cell Growth & Differ., 4: 467-473, 1993). We also found that constitutive bcl-2 expression inhibits wt p53-triggered apoptosis in these cells (Y. Wang et al., Oncogene, 8: 3427-3431, 1993). Here we demonstrate that more than 90% of the ts p53-transfected J3D cells were arrested in G1 at 18 h after induction of wt p53 expression by temperature shift to 32 degrees C. At this time, at least 80% of the cells remained viable. After 30 h at 32 degrees C, around 50% of the cells had died by apoptosis, while most of the remaining cells were still alive in G1, indicating that p53-induced apoptosis occurred following G1 arrest. The G1 cell cycle arrest at 18 h after temperature shift to 32 degrees C was reversible, as shown by the fact that the cells readily resumed exponential growth following temperature shift back to 37 degrees C, although viability dropped from around 80 to 65%. Expression of both WAF1 and bax mRNA was induced by wt p53 in both the ts p53 and ts p53/bcl-2 transfected cells. The kinetics of G1 cell cycle arrest at 32 degrees C was similar in both the ts p53 and the ts p53/bcl-2 double transfectants.(ABSTRACT TRUNCATED AT 250 WORDS)

Wild-type p53-triggered apoptosis is inhibited by bcl-2 in a v-myc-induced T-cell lymphoma line

Using a temperature sensitive p53 construct (ts p53), we have earlier shown that expression of wild-type (wt) p53 triggers apoptosis in a v-myc-induced T-cell lymphoma line that lacks endogenous p53, and in a Burkitt lymphoma line that carries mutant p53. We have suggested that apoptosis is elicited by the contradictory signals emanating from the constitutively activated myc gene and the growth arresting signal of wt p53 (Ramqvist et al., 1993; Wang et al., 1993). Work in other laboratories has shown that constitutive c-myc expression can induce apoptosis when cell proliferation is inhibited due to the lack of growth stimulating factors. Expression of bcl-2 could inhibit apoptosis. In order to test whether p53-induced apoptosis can be prevented by bcl-2, we have introduced a retrovirally driven bcl-2 construct into our v-myc-induced murine T-cell lymphoma line, previously transfected with ts p53. About 90% of the parental ts p53 transfected cells died of apoptosis within 3 days after induction of wt p53 expression at 32 degrees C. Two clones of ts p53/bcl-2 double transfectants that expressed high levels of bcl-2 from the introduced construct were completely protected from apoptosis, following transfer of the cells to 32 degrees C. One clone that expressed the exogenous bcl-2 only at a low level was partially protected from wt p53-induced apoptosis. Clones of the parental ts p53 carrying cells transfected with the puromycin resistance gene vector, without the bcl-2 gene underwent 90% apoptosis. These results suggest that bcl-2 may prevent apoptosis in cells simultaneously exposed to the proliferation-stimulating effect of activated myc and the growth arresting signal of wt p53.