Perineural invasion and associated pain in pancreatic cancer

Perineural invasion (PNI) is a prominent characteristic of pancreatic cancer. PNI is a process whereby cancer cells invade the surrounding nerves, thus providing an alternative route for metastatic spread and pain generation. PNI is thought to be an indicator of aggressive tumour behaviour and has been shown to correlate with poor prognosis of patients with pancreatic cancer. Recent studies demonstrated that some signalling molecules and pathways that are involved in PNI are also involved in pain generation. Targeting these signalling pathways has shown some promise in alleviating pain and reducing PNI, which could potentially improve treatment outcomes for patients with pancreatic cancer.     

Promoter methylation of Wnt5a is associated with microsatellite instability and BRAF V600E mutation in two large populations of colorectal cancer patients

Background:

In colorectal cancer (CRC), tumour microsatellite instability (MSI) status and CpG island methylator phenotype (CIMP) status are indicators of patient outcome, but the molecular events that give rise to these outcomes remain largely unknown. Wnt5a is a critical regulator of non-canonical Wnt activity and promoter hypermethylation of this gene has emerging prognostic roles in CRC; however the frequency and prognostic significance of this epigenetic event have not been explored in the context of colorectal tumour subtype. Consequently, we investigated the frequency and prognostic significance of Wnt5a methylation in a large cohort of MSI-stratified CRCs.

Methods:

Methylation was quantified in a large cohort of 1232 colorectal carcinomas from two clinically distinct populations from Canada. Associations were examined between methylation status and clinicopathlogical features, including tumour MSI status, BRAF V600E mutation, and patient survival.

Results:

In Ontario, Wnt5a methylation was strongly associated with MSI tumours after adjustment for age, sex, and tumour location (odds ratio (OR)=4.2, 95% confidence interval (CI)=2.4–7.4, P<10⁻⁶) and with BRAF V600E mutation, a marker of CIMP (OR=12.3, 95% CI=6.9–21.7, P<10⁻¹⁷), but was not associated with patient survival. Concordant results were obtained in Newfoundland.

Conclusion:

Methylation of Wnt5a is associated with distinct tumour subtypes, strengthening the evidence of an epigenetic-mediated Wnt bias in CRC.     

Evaluation of pharmaceutical excipients as cosolvents in 4-methyl umbelliferone glucuronidation in human liver microsomes: applications for compounds with low solubility

Standard incubation procedures for carrying out microsomal assays involve the use of less than 1% w/v organic solvents to minimize the potential inhibitory effects of organic solvents on metabolic activity. This presents a practical limitation for poorly soluble xenobiotics, which cannot be incubated at concentrations high enough to obtain a V(max), and therefore subsequent values for K(m) and Cl(int) cannot be calculated. Our goal was to study the application of a variety of pharmaceutical excipients to aid the solubilization of compounds in vitro in glucuronidation incubations, without affecting the reaction kinetics. In vitro glucuronidation incubations were carried out in human liver microsomes with 4-methylumbelliferone (4-MU) and the kinetics of 4-MU glucuronidation in the presence of excipients were compared to that in control incubations without any excipients. In addition, IC(75) values were calculated for each excipient. We observed that HPBCD (Hydroxypropyl-β-cyclodextrin) may be employed in in vitro glucuronidation incubations up to 0.5% w/v without affecting the Cl(int) of 4-MU. Although NMP (N-methyl-2-pyrrolidone) and DMA (N,N-dimethylacetamide); showed low IC(75) values approximately 0.1% w/v each, neither excipients altered the Cl(int) of 4-MUG (4-methylumbelliferyl-β-D-glucuronide) formation. Our studies point toward possible applications of pharmaceutical excipients to carry out in vitro glucuronidation of substrates with poor aqueous solubility, in order to estimate Cl(int) and subsequently scaled organ clearance values.     

Detection of medullary carcinoma of thyroid, with liver metastasis, using 99mTc DMSA(V) scintigraphy

A sixty year old female referred for thyroid and liver scintigraphy had a clinical history of progressive swelling in the neck with hepatomegaly. A large cold area was detected in the right thyroid lobe using 99mTc pertechnetate and in the right lobe of liver using 99mTc phytate. Subsequent whole body scan with 99mTC DMSA(V) showed avid tracer uptake in right lobe of thyroid and liver. Aspiration cytology of thyroid and liver showed medullary carcinoma of thyroid with its metastasis in liver. Histopathology following thyroidectomy confirmed the diagnosis. Thus 99mTc pentavalent DMSA contributes specificity to diagnose medullary carcinoma of thyroid and metastatic lesions.     

Immunohistochemistry versus microsatellite instability testing in phenotyping colorectal tumors.

PURPOSE: To compare microsatellite instability (MSI) testing with immunohistochemical (IHC) detection of hMLH1 and hMSH2 in colorectal cancer. PATIENTS AND METHODS: Colorectal cancers from 1,144 patients were assessed for DNA mismatch repair deficiency by two methods: MSI testing and IHC detection of hMLH1 and hMSH2 gene products. High-frequency MSI (MSI-H) was defined as more than 30% instability of at least five markers; low-level MSI (MSI-L) was defined as 1% to 29% of loci unstable. RESULTS: Of 1,144 tumors tested, 818 showed intact expression of hMLH1 and hMSH2. Of these, 680 were microsatellite stable (MSS), 27 were MSI-H, and 111 were MSI-L. In all, 228 tumors showed absence of hMLH1 expression and 98 showed absence of hMSH2 expression: all were MSI-H. CONCLUSION: IHC in colorectal tumors for protein products hMLH1 and hMSH2 provides a rapid, cost-effective, sensitive (92.3%), and extremely specific (100%) method for screening for DNA mismatch repair defects. The predictive value of normal IHC for an MSS/MSI-L phenotype was 96.7%, and the predictive value of abnormal IHC was 100% for an MSI-H phenotype. Testing strategies must take into account acceptability of missing some cases of MSI-H tumors if only IHC is performed.     

Hybrid magnetic nanostructures (MNS) for magnetic resonance imaging applications

The development of MRI contrast agents has experienced its version of the gilded age over the past decade, thanks largely to the rapid advances in nanotechnology. In addition to progress in single mode contrast agents, which ushered in unprecedented R(1) or R(2) sensitivities, there has also been a boon in the development of agents covering more than one mode of detection. These include T(1)-PET, T(2)-PET T(1)-optical, T(2)-optical, T(1)-T(2) agents and many others. In this review, we describe four areas which we feel have experienced particular growth due to nanotechnology, specifically T(2) magnetic nanostructure development, T(1)/T(2)-optical dual mode agents, and most recently the T(1)-T(2) hybrid imaging systems. In each of these systems, we describe applications including in vitro, in vivo usage and assay development. In all, while the benefits and drawbacks of most MRI contrast agents depend on the application at hand, the recent development in multimodal nanohybrids may curtail the shortcomings of single mode agents in diagnostic and clinical settings by synergistically incorporating functionality. It is hoped that as nanotechnology advances over the next decade, it will produce agents with increased diagnostics and assay relevant capabilities in streamlined packages that can meaningfully improve patient care and prognostics. In this review article, we focus on T(2) materials, its surface functionalization and coupling with optical and/or T(1) agents.     

Association of tissue promoter methylation levels of APC, TGFβ2, HOXD3 and RASSF1A with prostate cancer progression

Aberrant promoter methylation is known to silence tumor-suppressor genes in prostate cancer (PCa). We correlated quantitative promoter methylation levels of APC, TGFβ2 and RASSF1A in 219 radical prostatectomies diagnosed between 1998 and 2001 with clinicopathological follow-up data available including Gleason Pattern (GP), Gleason Score (GS) and pathological stage and explored their potential in predicting biochemical recurrence using univariate and multivariate analyses. We observed that the average methylation levels of APC increased significantly from GS ≤ 6 to GS7, and pT2 to pT3a, and that of TGFβ2 increased from GS ≤ 6 to GS7, but not for RASSF1A. PCa samples were also stratified into high methylation (HM) and low methylation (LM) groups based on the PMR scores of all cases analyzed for each marker. The HM frequency of APC was greater in pT3a than pT2, and in GS ≥ 8 than GS ≤ 6. The HM frequency also increased significantly from GP3 to GP4 for APC, TGFβ2 and RASSF1A. APC methylation level was a significant predictor of biochemical recurrence in univariate analysis (p-value = 0.028). Finally, we combined methylation data of these three genes with the previously reported novel methylation biomarker HOXD3. Quantitative methylation assessment of a multiplex panel of markers, consisting of APC, HOXD3 and TGFβ2, outperforms any single marker for the prediction of biochemical recurrence (p-value = 0.017). Our study demonstrated that quantitative increase in promoter methylation levels of APC, HOXD3 and TGFβ2 are associated with PCa progression.     

Quality assessment and correlation of microsatellite instability and immunohistochemical markers among population- and clinic-based colorectal tumors results from the Colon Cancer Family Registry

The detection of defective mismatch repair (MMR), as assessed by the presence of tumor microsatellite instability (MSI) and/or loss of MMR protein expression by IHC, has been useful for risk assessment, prognosis, and prediction of treatment in patients with colorectal cancer. We analyzed tumors for the presence of defective MMR from 5927 Colorectal Cancer Family Registry patients recruited at six international consortium sites. We evaluated the appropriate percentage instability cutoff used to distinguish the three MSI phenotypes [ie, stable (MSS), low instability (MSI-L), and high instability (MSI-H)]; the sensitivity, specificity, and performance characteristics of individual markers; and the concordance between MSI and IHC phenotypes. Guided by the results of the IHC testing, our findings indicate that the distinction between an MSI-H phenotype from a low-instability or MSS phenotype can best be accomplished by using a cutoff of 30% or greater of the markers showing instability. The sensitivity and specificity of the mononucleotide markers were higher than those of the dinucleotide markers. Specifically, BAT26 and BAT25 had the highest sensitivity (94%) and specificity (98%), and the use of mononucleotide markers alone identified 97% of the MSI-H cases correctly. As expected, the presence of MSI-H correlated with an older age of diagnosis, the presence of tumor in the proximal colon, and female sex.