The role of infiltrating lymphocytes in the neo-adjuvant treatment of women with HER2-positive breast cancer.

BACKGROUND: Pre-treatment tumour-associated lymphocytes (TILs) and stromal lymphocytes (SLs) are independent predictive markers of future pathological complete response (pCR) in HER2-positive breast cancer. Whilst studies have correlated baseline lymphocyte levels with subsequent pCR, few have studied the impact of neoadjuvant therapy on the immune environment. METHODS: We performed TIL analysis and T-cell analysis by IHC on the pretreatment and 'On-treatment' samples from patients recruited on the Phase-II TCHL (NCT01485926) clinical trial. Data were analysed using the Wilcoxon signed-rank test and the Spearman rank correlation. RESULTS: In our sample cohort (n = 66), patients who achieved a pCR at surgery, post-chemotherapy, had significantly higher counts of TILs (p = 0.05) but not SLs (p = 0.08) in their pre-treatment tumour samples. Patients who achieved a subsequent pCR after completing neo-adjuvant chemotherapy had significantly higher SLs (p = 9.09 × 10-3) but not TILs (p = 0.1) in their 'On-treatment' tumour biopsies. In a small cohort of samples (n = 16), infiltrating lymphocyte counts increased after 1 cycle of neo-adjuvant chemotherapy only in those tumours of patients who did not achieve a subsequent pCR. Finally, reduced CD3 + (p = 0.04, rho = 0.60) and CD4 + (p = 0.01, rho = 0.72) T-cell counts in 'On-treatment' biopsies were associated with decreased residual tumour content post-1 cycle of treatment; the latter being significantly associated with increased likelihood of subsequent pCR (p < 0.01). CONCLUSIONS: The immune system may be 'primed' prior to neoadjuvant treatment in those patients who subsequently achieve a pCR. In those patients who achieve a pCR, their immune response may return to baseline after only 1 cycle of treatment. However, in those who did not achieve a pCR, neo-adjuvant treatment may stimulate lymphocyte influx into the tumour.

Meta-analysis of the molecular associations of mucinous colorectal cancer.

BACKGROUND: Mucinous differentiation occurs in 5-15 per cent of colorectal adenocarcinomas. This subtype of colorectal cancer responds poorly to chemoradiotherapy and has a worse prognosis. The genetic aetiology underpinning this cancer subtype lacks consensus. The aim of this study was to use meta-analytical techniques to clarify the molecular associations of mucinous colorectal cancer. METHODS: This study adhered to MOOSE guidelines. Databases were searched for studies comparing KRAS, BRAF, microsatellite instability (MSI), CpG island methylator phenotype (CIMP), p53 and p27 status between patients with mucinous and non-mucinous colorectal adenocarcinoma. A random-effects model was used for analysis. RESULTS: Data from 46 studies describing 17 746 patients were included. Mucinous colorectal adenocarcinoma was associated positively with KRAS (odds ratio (OR) 1·46, 95 per cent c.i. 1·08 to 2·00, P = 0·014) and BRAF (OR 3·49, 2·50 to 4·87; P < 0·001) mutation, MSI (OR 3·98, 3·30 to 4·79; P < 0·001) and CIMP (OR 3·56, 2·85 to 4·43; P < 0·001), and negatively with altered p53 expression (OR 0·46, 0·31 to 0·67; P < 0·001). CONCLUSION: The genetic origins of mucinous colorectal adenocarcinoma are predominantly associated with BRAF, MSI and CIMP pathways. This pattern of molecular alterations may in part explain the resistance to standard chemotherapy regimens seen in mucinous adenocarcinoma.

Differential p16/INK4A cyclin-dependent kinase inhibitor expression correlates with chemotherapy efficacy in a cohort of 88 malignant pleural mesothelioma patients.

BACKGROUND: Malignant pleural mesothelioma (MPM) is a rare and essentially incurable malignancy most often linked with occupational exposure to asbestos fibres. In common with other malignancies, the development and progression of MPM is associated with extensive dysregulation of cell cycle checkpoint proteins that modulate cell proliferation, apoptosis, DNA repair and senescence. METHODS: The expression of cyclin-dependent kinase inhibitor p16/INK4A was evaluated by immunohistochemistry using tumour biopsy specimens from 88 MPM cases and a semi-quantitative score for p16/INK4A expression was obtained. Post-diagnosis survival and the survival benefit of chemotherapeutic intervention was correlated with p16/INK4A expression. RESULTS: A low, intermediate and high score for p16/INK4A expression was observed for 45 (51.1%), 28 (31.8%) and 15 (17.1%) of the MPM cases, respectively. Those cases with intermediate or high p16/INK4A tumour expression had a significantly better post-diagnosis survival than those cases whose tumours lost p16 expression (log-rank P<0.001). Those patients with sustained p16/INK4A expression who received chemotherapy also had a better survival than those treated patients whose tumours had lost p16/INK4A expression (log-rank P<0.001). CONCLUSIONS: Sustained p16/INK4A expression predicts better post-diagnosis survival in MPM and also better survival following chemotherapeutic intervention.

The prognostic value of tumour regression grade following neoadjuvant chemoradiation therapy for rectal cancer.

AIM: To date, there is no uniform consensus on whether tumour regression grade (TRG) is predictive of outcome in rectal cancer. Furthermore, the lack of standardization of TRG grading is a major source of variability in published studies. The aim of this study was to evaluate the prognostic impact of TRG in a cohort of patients with locally advanced rectal cancer treated with neoadjuvant chemoradiation therapy (CRT). In addition to the Mandard TRG, we utilized four TRG systems modified from the Mandard TRG system and applied them to the cohort to assess which TRG system is most informative. METHOD: One-hundred and fifty-three patients with a T3/T4 and/or a node-positive rectal cancer underwent neoadjuvant 5-fluorouracil-based CRT followed by surgical resection. RESULTS: Thirty-six (23.5%) patients achieving complete pathological response (ypCR) had a 5-year disease-free survival (DFS) rate of 100% compared with a DFS rate of 74% for 117 (76.5%) patients without ypCR (P = 0.003). The Royal College of Pathologists (RCPath) TRG best condenses the Mandard five-point TRG by stratifying patients into three groups with distinct 5-year DFS rates of 100%, 86% and 67%, respectively (P = 0.001). In multivariate analysis, pathological nodal status and circumferential resection margin (CRM) status, but not TRG, remained significant predictors of DFS (P = 0.002, P = 0.035 and P = 0.310, respectively). CONCLUSION: Our findings support the notion that ypCR status, nodal status after neoadjuvant CRT and CRM status, but not TRG, are predictors of long-term survival in patients with locally advanced rectal cancer.

Apoptosome-dependent caspase activation proteins as prognostic markers in Stage II and III colorectal cancer.

BACKGROUND: Critical to successful execution of mitochondrial-mediated apoptosis is apoptosome formation and subsequent activation of caspases. Defects in this pathway have an important role in colorectal carcinogenesis and chemoresistance; therefore, the expression of apoptosome-associated proteins may be associated with clinical outcome and response to chemotherapy. METHODS: Here we performed a systematic analysis of the immunohistochemical expression of the key proteins involved in apoptosome-dependent caspase activation (APAF1, Pro-caspases 9 and 3, SMAC, and XIAP) in a cohort of Stage II and III colorectal cancer patients from a Phase III trial of adjuvant 5-fluorouracil-based chemotherapy vs postoperative observation alone. RESULTS: Survival analysis indicated that of the apoptosome-associated proteins examined here, Pro-caspase 3 and APAF1 have potential clinical utility as predictive markers in Stage II and III colorectal cancer, respectively. Interestingly, we identified APAF1 staining to be associated with better recurrence-free and overall survival in patients receiving chemotherapy. CONCLUSION: These studies reveal the importance of the apoptosome-dependent caspase activation pathway, specifically Pro-caspase 3 and APAF1 proteins, for predicting both prognosis and response to therapy.

The expression and prognostic impact of CXC-chemokines in stage II and III colorectal cancer epithelial and stromal tissue.

BACKGROUND: The CXC-chemokine expression is linked with colorectal cancer (CRC) progression but their significance in resected CRC is unclear. We explored the prognostic impact of such expression in stage II and III CRC. METHODS: Tissue microarrays were constructed from stage II and III CRC biopsies (n=254), and the expression of CXCL1 and CXCL8, and their receptors CXCR1 and CXCR2, in malignant and adjacent normal tissue was graded by immunohistochemistry and was correlated with prognostic factors. RESULTS: Expression of CXCL1, CXCR1 and CXCR2 was elevated in tumour epithelium relative to normal adjacent tissue (P<0.001). CXCL8 expression was detectable in the peritumoural inflammatory infiltrate. There was no overall association between CXCL1, CXCR1 or CXCR2 expression and prognostic endpoints; however, univariate subgroup survival analysis demonstrated an inverse association between CXCL1 and recurrence-free survival (RFS) in stage III patients (P=0.041). The CXCL8 positivity in the tumour infiltrate, however, correlated with earlier disease stage (P<0.001) and improved relapse-free survival across the cohort (P<0.001). Disease stage (P<0.001) and tumour infiltrate CXCL8 positivity (P=0.007) were associated with enhanced RFS in multivariate Cox regression analysis. CONCLUSION: Autocrine CXC-chemokine signalling may have adverse prognostic effects in early CRC. Conversely, CXCL8 positivity within the immune infiltrate may have good prognostic significance.

The role of Cathepsin S as a marker of prognosis and predictor of chemotherapy benefit in adjuvant CRC: a pilot study.

BACKGROUND: The aim of this pilot retrospective study was to investigate the immunohistochemical expression of Cathepsin S (CatS) in three cohorts of colorectal cancer (CRC) patients (n=560). METHODS: Prevalence and association with histopathological variables were assessed across all cohorts. Association with clinical outcomes was investigated in the Northern Ireland Adjuvant Chemotherapy Trial cohort (n=211), where stage II/III CRC patients were randomised between surgery-alone or surgery with adjuvant fluorouracil/folinic acid (FU/FA) treatment. RESULTS: Greater than 95% of tumours had detectable CatS expression with significantly increased staining in tumours compared with matched normal colon (P>0.001). Increasing CatS was associated with reduced recurrence-free survival (RFS; P=0.03) among patients treated with surgery alone. Adjuvant FU/FA significantly improved RFS (hazard ratio (HR), 0.33; 95% CI, 0.12-0.89) and overall survival (OS; HR, 0.25; 95% CI, 0.08-0.81) among 36 patients with high CatS. Treatment did not benefit the 66 patients with low CatS, with a RFS HR of 1.34 (95% CI, 0.60-3.19) and OS HR of 1.33 (95% CI, 0.56-3.15). Interaction between CatS and treatment status was significant for RFS (P=0.02) and OS (P=0.04) in a multivariate model adjusted for known prognostic markers. CONCLUSION: These results signify that CatS may be an important prognostic biomarker and predictive of response to adjuvant FU/FA in CRC.

Human IgG antibody profiles differentiate between symptomatic patients with and without colorectal cancer.

OBJECTIVE: Patients with cancer have antibodies against tumour antigens. Characterising the antibody repertoire may provide insights into aberrant cellular mechanisms in cancer development, ultimately leading to novel diagnostic or therapeutic targets. The aim of this study was to characterise the antibody profiles in patients whose symptoms warranted colonoscopy, to see if there was a difference in patients with and without colorectal cancer. METHODS: Patients were recruited from a colonoscopy clinic. Individual serum samples from 43 patients with colorectal cancer and 40 patients with no cancer on colonoscopy were profiled on a 37 830 clone recombinant human protein array. Antigen expression was evaluated by quantitative reverse transcription-PCR and by immunohistochemistry on tissue microarrays. RESULTS: Using a sex- and age-matched training set, 18 antigens associated with cancer and 4 associated with the absence of cancer (p<0.05) were identified and confirmed. To investigate the mechanisms triggering antibody responses to these antigens, antigen expression was examined in normal colorectal mucosa and colorectal carcinoma of the same patients. The identified antigens showed cellular accumulation (p53), aberrant cellular expression (high mobility group B1 (HMGB1)) and overexpression (tripartite motif-containing 28 (TRIM28), p53, HMGB1, transcription factor 3 (TCF3), longevity assurance gene homologue 5 (LASS5) and zinc finger protein 346 (ZNF346)) in colorectal cancer tissue compared with normal colorectal mucosa. CONCLUSIONS: It is demonstrated for the first time that screening high-density protein arrays identifies unique antibody profiles that discriminate between symptomatic patients with and without colorectal cancer. The differential expression of identified antigens suggests their involvement in aberrant cellular mechanisms in cancer.

Aberrant DNA methylation associated with MTHFR C677T genetic polymorphism in cutaneous squamous cell carcinoma in renal transplant patients.

BACKGROUND: Changes in genomic DNA methylation associated with cancer include global DNA hypomethylation and gene-specific hyper- or hypomethylation. We have previously identified a genetic variant in the MTHFR gene involved in the methylation pathway which confers risk for the development of squamous cell carcinoma (SCC) in renal transplant patients. This genetic variant has also been discovered to confer SCC risk in nontransplant patients with low folate status. OBJECTIVES: To explore the methylation profile of SCC compared with adjacent non-neoplastic skin using pyrosequencing, and to elucidate whether the MTHFR polymorphism impacts upon the methylation patterns in SCC. METHODS: We used pyrosequencing to evaluate global (using long interspersed nuclear element 1) and gene-specific (p16 and MGMT) methylation status in 47 SCCs and 40 adjacent autologous non-neoplastic skin samples in those with (n = 16) and without (n = 17) the MTHFR polymorphism. RESULTS: Pyrosequencing methylation analysis revealed that SCC was hypomethylated compared with adjacent non-neoplastic skin (P < 0.04). Patients with the MTHFR polymorphism had higher levels of global methylation in tumours and non-neoplastic skin compared with those without the MTHFR polymorphism (P < 0.002). There was no association between levels of methylation in tumour and non-neoplastic skin for the genes MGMT and p16. CONCLUSIONS: Global hypomethylation appears to be a feature of SCC. Aberrant methylation of DNA appears related to polymorphisms of MTHFR. Such findings suggest that intervention in the form of demethylating agents or folate supplementation might be beneficial in the treatment or prevention of SCC.

Regulation of the apoptosis-inducing kinase DRAK2 by cyclooxygenase-2 in colorectal cancer.

BACKGROUND: Cyclooxygenase-2 (COX-2) is over-expressed in colorectal cancer (CRC), rendering tumour cells resistant to apoptosis. Selective COX-2 inhibition is effective in CRC prevention, although having adverse cardiovascular effects, thus focus has shifted to downstream pathways. METHODS: Microarray experiments identified genes regulated by COX-2 in HCA7 CRC cells. In vitro and in vivo regulation of DRAK2 (DAP kinase-related apoptosis-inducing kinase 2 or STK17beta, an apoptosis-inducing kinase) by COX-2 was validated by qRT-PCR. RESULTS: Inhibition of COX-2 induced apoptosis and enhanced DRAK2 expression in HCA7 cells (4.4-fold increase at 4 h by qRT-PCR, P=0.001), an effect prevented by co-administration of PGE(2). DRAK2 levels were suppressed in a panel of human colorectal tumours (n=10) compared to normal mucosa, and showed inverse correlation with COX-2 expression (R=-0.68, R2=0.46, P=0.03). Administration of the selective COX-2 inhibitor rofecoxib to patients with CRC (n=5) induced DRAK2 expression in tumours (2.5-fold increase, P=0.01). In vitro silencing of DRAK2 by RNAi enhanced CRC cell survival following COX-2 inhibitor treatment. CONCLUSION: DRAK2 is a serine-threonine kinase implicated in the regulation of apoptosis and is negatively regulated by COX-2 in vitro and in vivo, suggesting a novel mechanism for the effect of COX-2 on cancer cell survival.

Survival and progression in high grade tumour subset of G2 and G3 pT1 bladder transitional cell carcinoma.

AIMS: The newer 1998 WHO/ISUP grading system for bladder transitional cell carcinoma combined grade 3 (G3) and high grade tumour subset of grade 2 (G2) of the older 1973 WHO grading system into one homogenous high grade group. We evaluated for possible differences in survival and progression between these 2 grades in pT1 bladder tumours. METHODS: From Jan 1(st) 1991-Dec 31(st) 2003, 105 (61 G2 and 44 G3) pT1 bladder tumours fulfilled the 1998 WHO/ISUP high grade criteria. Survival and progression of these tumours were assessed. RESULTS: Of the 44 patients with G3 tumours, 20 are alive versus 22 of the 61 patients with high grade tumour subset of G2 (P=0.04). Of the 44 patients with G3 tumours, 13 progressed versus 12 of the 61 patients with high grade tumour subset of G2 (P=0.02). In multivariate analysis, G3 was a significant predictor of tumour progression (P=0.05) and marginally non-significant predictor of poor patient survival (P=0.056). CONCLUSIONS: A notable difference in survival and progression between high grade tumour subset of G2 and G3 is observed.

Low levels of Caspase-3 predict favourable response to 5FU-based chemotherapy in advanced colorectal cancer: Caspase-3 inhibition as a therapeutic approach.

Colorectal cancer (CRC) is one of the most common cancers in the Western world. 5-Fluorouracil (5FU)-based chemotherapy (CT) remains the mainstay treatment of CRC in the advanced setting, and activates executioner caspases in target cells. Executioner caspases are key proteins involved in cell disassembly during apoptosis. Activation of executioner caspases also has a role in tissue regeneration and repopulation by stimulating signal transduction and cell proliferation in neighbouring, non-apoptotic cells as reported recently. Tissue microarrays (TMAs) consisting of tumour tissue from 93 stage II and III colon cancer patients were analysed by immunohistochemistry. Surprisingly, patients with low levels of active Caspase-3 had an increased disease-free survival time. This was particularly pronounced in patients who received 5FU-based adjuvant CT. In line with this observation, lower serum levels of active Caspase-3 were found in patients with metastasised CRC who revealed stable disease or tumour regression compared with those with disease progression. The role of Caspase-3 in treatment responses was explored further in primary human tumour explant cultures from fresh patient tumour tissue. Exposure of explant cultures to 5FU-based CT increased the percentage of cells positive for active Caspase-3 and Terminal Deoxynucleotidyl Transferase dUTP Nick end Labelling (TUNEL), but also the expression of regeneration and proliferation markers ß-Catenin and Ki-67, as well as cyclooxygenase-2 (COX-2). Of note, selective inhibition of Caspase-3 with Ac-DNLD-CHO, a selective, reversible inhibitor of Caspase-3, significantly reduced the expression of proliferation markers as well as COX-2. Inhibition of COX-2 with aspirin or celecoxib did not affect Caspase-3 levels but also reduced Ki-67 and ß-Catenin levels, suggesting that Caspase-3 acted via COX-2 to stimulate cell proliferation and tissue regeneration. This indicates that low levels of active Caspase-3 may represent a new predictor of CT responsiveness, and inhibition of Caspase-3, or antagonising downstream effectors of Caspase-3 paracrine signalling, such as COX-2 may improve patient outcomes following CT in advanced CRC.

High levels of X-linked Inhibitor-of-Apoptosis Protein (XIAP) are indicative of radio chemotherapy resistance in rectal cancer.

BACKGROUND: The mainstay of treatment in rectal cancer is neoadjuvant radio chemotherapy prior to surgery, in an attempt to downstage the tumour, allowing for more complete removal during surgery. In 40 % of cases however, this neoadjuvant radio chemotherapy fails to achieve tumour regression, partly due insufficient apoptosis signaling. X-linked Inhibitor of Apoptosis Protein (XIAP) is an anti-apoptotic protein that has been reported to contribute to disease progression and chemotherapy resistance. METHODS: We obtained rectal biopsy normal and matched tumour tissue from 29 rectal cancer patients with varying degrees of tumour regression, and using Western blot, examined anti-apoptotic XIAP and pro-apoptotic Smac protein levels in these tissues, with the aim to examine whether disturbed XIAP/Smac levels may be an indicator of neoadjuvant radio chemotherapy resistance. Expression of inhibitor of apoptosis proteins cIAP-1 and cIAP-2 was also examined. RESULTS: We found that levels of XIAP increased in accordance with the degree of radio chemotherapy resistance of the tissue. Levels of this protein were also significantly higher in tumour tissue, compared to matched normal tissue in highly resistant tissue. In contrast, Smac protein levels did not increase with radio chemotherapy resistance, and the protein was similarly expressed in normal and tumour tissue, indicating a shift in the balance of these proteins. Post treatment surgical resection tissue was available for 8 patients. When we compared matched tissue pre- and post- radio chemotherapy we found that XIAP levels increased significantly during treatment in both normal and tumour tissue, while Smac levels did not change. cIAP-1 and cIAP-2 levels were not differentially expressed in varying degrees of radio chemotherapy resistance, and neoadjuvant therapy did not alter expression of these proteins. CONCLUSION: These data indicate that disturbance of the XIAP/Smac balance may be a driver of radio chemotherapy resistance, and hence high levels of XIAP may be a useful indicator of neoadjuvant radio chemotherapy resistance in rectal cancer. Moreover, as XIAP levels increase with radio chemotherapy it is possible that a subset of more resistant tumour cells survive this treatment and may be resistant to further adjuvant treatment. Patients with resistant tumours highly expressing XIAP may benefit from alternative treatment strategies, such as Smac mimetics post neoadjuvant radio chemotherapy.

BCL2 protein signalling determines acute responses to neoadjuvant chemoradiotherapy in rectal cancer.

UNLABELLED: In locally advanced rectal cancer, neoadjuvant chemoradiotherapy is performed prior to surgery to downstage the tumour. Thirty to 40 % of patients do not respond. Defects in apoptotic machinery lead to therapy resistance; however, to date, no study quantitatively assessed whether B cell lymphoma 2 (BCL2)-dependent regulation of mitochondrial apoptosis, effector caspase activation downstream of mitochondria or a combination of both predicts patient responses. In a cohort of 20 rectal cancer patients, we performed protein profiling of tumour tissue and employed validated ordinary differential equation-based systems models of apoptosis signalling to calculate the ability of cancer cells to undergo apoptosis. Model outputs were compared to clinical responses. Systems modelling of BCL2-signalling predicted patients in the poor response group (p = 0.0049). Systems modelling also demonstrated that rectal cancers depended on BCL2 rather than B cell lymphoma-extra large (BCL(X)L) or myeloid cell leukemia 1 (MCL1) for survival, suggesting that poor responders may benefit from therapy with selective BCL2 antagonists. Dynamic modelling of effector caspase activation could not stratify patients with poor response and did not further improve predictive power. We deliver a powerful patient stratification tool identifying patients who will likely not benefit from neoadjuvant chemoradiotherapy and should be prioritised for surgical resection or treatment with BCL2 antagonists. KEY MESSAGES: Modelling BCL2-family proteins identifies patients unresponsive to therapy. Caspase activation downstream of mitochondria cannot identify these patients. Rectal tumours of poor responders are BCL2- but not BCL-XL-dependent. DR_MOMP allows clinicians to identify patients who would not benefit from therapy. DR_MOMP is also a useful patient stratification tool for BCL2 antagonists.

An image analysis study of DNA content in early colorectal cancer.

The DNA content of 168 consecutive T3,N0,M0 (Dukes' B, Astler-Coller B2) colorectal cancers was studied using image analysis on formalin-fixed paraffin-embedded tissues. 72 cases (43%) were classified as diploid and the remaining 96 (57%) as non-diploid. After a median follow-up period of 6.7 years, a significant survival advantage was found for diploid compared with non-diploid cases (logrank test; P = 0.008). The long-term (8 year) survival rate was 70% for diploid and 46% for non-diploid tumours. Subgroup analysis showed that the survival advantage conferred by tumour diploidy was greatest in large (> or = 5 cm) cancers and was found both in colonic and rectal cancer cases. These data indicate that tumour ploidy status measured by image analysis might be useful in determining risk of colorectal cancer recurrence and death in patients following resection of early colorectal cancer.

Bleeding due to colorectal atheroembolism. Diagnosis by biopsy of adenomatous polyps or of ischemic ulcer.

Atheroembolism, although not infrequent at autopsy, is seldom identified in life, when it may present as a multisystem disease involving lower limbs, kidney, and gastrointestinal (GI) tract. Diagnosis of isolated GI involvement usually requires examination of surgically resected tissue, because recognition by endoscopic GI biopsy is exceptional. We diagnosed colorectal atheroembolism by biopsy in four patients. All were elderly (68-80 years old) and had generalized atheroma, including aortic aneurysms. Three patients had sudden onset of frank rectal bleeding with clots or bloody diarrhea, lower abdominal discomfort, and tenderness. Biopsy revealed atheroemboli in a rectal ischemic ulcer and in colorectal adenomatous polyps. In all three, disease resolved on conservative management and did not recur during the period of follow-up. In the fourth patient, asymptomatic atheroembolism was identified in an adenomatous polyp at the splenic flexure. Extraintestinal disease attributable to atheroembolism was not present in any of the patients. Atheroembolism with manifestations confined to the colon may sometimes be diagnosed by biopsy, appears to be more frequent than currently recognized, and may present a diagnostic challenge as a self-limited episode of rectal bleeding.

Altered expression of the p53-regulated proteins, p21Waf1/Cip1, MDM2, and Bax in ultraviolet-irradiated human skin.

The distribution of p21WAf1/CiP1, MDM2, and Bax/Bcl-2 proteins in ultraviolet (UV)-irradiated and nonirradiated human skin was examined immunohistochemically and compared with p53 protein levels. Sun-protected buttock skin from three volunteers was exposed to solar simulated irradiation, and biopsies were performed 0.5, 1, 2, 4, and 24 hours after irradiation as well as control unirradiated skin from the opposite buttock. A similar staining pattern was observed in each of the three volunteers. P53 protein was detectable in all skin samples examined. P21Waf1/CiP1 protein was visible in the nuclei of cells at 4 hours, and staining intensity increased at 24 hours. MDM2 protein expression was noted in isolated nuclei in the epidermis at 24 hours. Bax cytoplasmic staining was evident in the basal layer of the epidermis of all samples, and this staining appeared to increase in intensity in the 4- and 24-hour specimens. There was no Bcl-2 immunohistochemical staining in any sample. These results suggest that p53 and genes/proteins under the control of p53 are altered/ activated in normal human skin in response to UV exposure.

Identification of vertical growth phase in malignant melanoma. A study of interobserver agreement.

Ninety-four H & E-stained slides of malignant melanoma were circulated to 6 pathologists in 2 university departments. For each slide, the growth phase of the lesion, Breslow thickness, and Clark level were determined by each observer. The aims of the study were to evaluate agreement between nonspecialist pathologists in identifying the vertical growth phase in malignant melanoma and to compare agreement for the growth phase with agreement for Breslow thickness and the Clark level. Our results show that although overall agreement for the growth phase is moderate, agreement between experienced observers is good. In fact agreement for the growth phase among this group was equal to the agreement for Breslow thickness. Overall agreement for Breslow thickness also was good but for the Clark level was only fair. These findings suggest that if the predictive value of the vertical growth phase proves to be robust, it will be used with an acceptable level of accuracy in routine diagnostic practice.