Anastomotic recurrence of colon cancer: Genetic analysis challenges the widely held theories of cancerous cells' intraluminal implantation and metachronous carcinogenesis

BACKGROUND AND OBJECTIVES

Anastomotic recurrence (AR), whose etiopathogenesis is attributed to intraluminal implantation of cancerous cells or metachronous carcinogenesis, is a major issue for patients undergoing colon cancer (CC) resection. The objective of the study is to throw some light on AR etiopathogenesis and to identify risk factors of AR in selecting patients to undergo early endoscopy.

METHODS

An analysis of clinical and histopathological parameters, including MSI and LOH of seven sites (Myc-L, BAT26, BAT40, D5S346, D18S452, D18S64, D16S402) was performed in primary CC and AR of 18 patients. They were then compared to 36 controls not developing AR.

RESULTS

A genetic instability was present in 16/18 patients, with distinct genetic patterns between primaries and ARs. LOH at 5q21 and/or 18p11.23 were found in both primary and AR in >50% of cases, but this rate was no different from control population. CEA resulted as associated with AR (P = 0.03), whereas N status presented a borderline result (P = 0.08).

CONCLUSIONS

Our findings challenge present theories about AR development. No "genetic marker" has been found. CEA and, to a lesser extent, N status, appear associated with AR. Rectal washout is seemingly meaningless. Iterative resection should be recommended since a long survival may be expected. J. Surg. Oncol. 2016;114:228-236. © 2016 Wiley Periodicals, Inc.

Isolation and Characterization of Circulating Tumor Cells in Squamous Cell Carcinoma of the Lung Using a Non-EpCAM-Based Capture Method

INTRODUCTION

The exclusion of circulating tumor cells (CTCs) that have lost epithelial antigens during the epithelial-to-mesenchymal transition (EMT) process by using Epithelial Cell Adhesion Molecule (EpCAM) based capture methods is still a matter of debate. In this study, cells obtained after depletion procedure from blood samples of squamous cell lung cancer (SQCLC) patients were identified based on morphology and characterized with the combination of FISH assessment and immunophenotypic profile.

MATERIALS AND METHODS

Five mL blood samples, collected from 55 advanced SQCLC patients, were analyzed by a non-EpCAM-based capture method. After depletion of leukocytes and erythroid cells, the negative fraction was characterized by both FISH using a fibroblast growth factor receptor 1 (FGFR1) probe and by immunocytochemistry. Thirty healthy donors were also tested.

RESULTS

Based on morphology (nuclear dimension ≥10 μm, shape and hypercromatic aspect) suspicious circulating cells clearly distinguishable from contaminant leukocytes were observed in 49/55 (89%) SQCLC patients. Thirty-four of the 44 (77%) samples evaluable for FGFR1 FISH showed ≥ 6 FGFR1 gene copy number on average per cell. Vimentin expression involved 43% (18/42) of pooled circulating SQCLC cells, whereas only 29% (14/48) were EpCAM positive. Confocal microscopy confirmed the localization of FGFR1 probe in suspicious circulating cells. Suspicious circulating elements were also observed in healthy donors and did not show any epithelial associated antigens. A significantly lower number of suspicious circulating cells in healthy donors compared to SQCLC patients was found.

CONCLUSIONS

Among the heterogeneous cell population isolated by depletion procedure, the coexistence of cells with epithelial and/or mesenchymal phenotype suggests that EMT may participate to transendothelial invasion and migration of tumor cells in advanced SQCLC. The finding of cells with neither EpCAM or EMT phenotype, retrieved after non-EpCAM-based systems, underlines the presence of suspicious elements in the blood of both SQCLC patients and healthy donors. Further phenotyping and molecular analyses are necessary to fully characterize these circulating elements.

Strong Notch activation hinders bevacizumab efficacy in advanced colorectal cancer

AIM

To assess the role of Notch activation in predicting bevacizumab efficacy in colorectal cancer (CRC).

MATERIALS & METHODS

Notch activation was evaluated by immunohistochemistry (IHC) on 65 CRC enrolled within randomized clinical trials assessing first-line bevacizumab-based chemotherapy and on 21 CRC treated with chemotherapy alone.

RESULTS

Strong Notch (IHC 3+) activation was negatively associated with response (18 vs 62% in low Notch cases [IHC 0, 1, 2+]; p = 0.016), progression-free survival (4.9 vs 12.1 months; p = 0.002) and overall survival (19.3 vs 30.4 months; p = 0.039). No correlation was found between Notch activation and clinical outcome in CRC treated with chemotherapy alone.

CONCLUSION

A potential role of Notch activation in the antitumor activity of bevacizumab could be hypothesized.

Notch expression and bevacizumab efficacy in colorectal cancer patients

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Background: Antiangiogenic therapies represent a well established additional treatment to standard chemotherapy, nevertheless no markers are available to suggest a successful outcome linked to the use of bevacizumab. To investigate potential mechanisms of resistance to angiogenesis inhibitor bevacizumab, Notch expression was correlated with response and survival in a series of bevacizumab treated advanced colorectal cancer (CRC) patients. Methods: Notch expression was evaluated by immunohistochemistry (IHC) on 65 primary CRC enrolled within 6 randomized clinical trials assessing first-line bevacizumab plus chemotherapy. Notch IHC was conducted using a polyclonal antibody to Cleaved Notch1 (Cell Signaling Technology, Danvers, MA). Notch expression was scored based on intensity of staining (0: none, 1+: weak, 2+: moderate; 3+: strong) and on percentage of immunostained cells. A control series of 21 advanced CRC treated with chemotherapy alone was also examined. Results: Notch positivity was localized to the cytoplasm or nucleus of malignant epithelial cells. In all, 11 of 61 (18%) evaluable primary tumours had a high Notch expression (IHC 3+). Six of the 11 cases (55%) with high Notch expression (IHC 3+) experienced progressive disease compared with 5 of 50 (10%) low Notch expression cases (IHC 0 1+ 2+) (p = 0.003). A high Notch expression also demonstrated an inferior median PFS (4.9 vs. 12.1 months; HR = 2.51; 95% CI, 0.96 to 6.58; p = 0.007) and OS (19.3 vs. 30.4 months; HR = 2.21; 95% CI, 0.79 to 6.15; p = 0.039) compared with low Notch expression cases. When the groups were further analyzed considering VEGF expression, the best outcome was found in low Notch (IHC 0 1 +) and high VEGF expressing tumors (IHC 2+ 3+) (response rate 9 of 11, 82 % vs. 1 of 5, 20%, in patients with high levels of Notch and VEGF expression, respectively). No correlation was found between Notch expression and clinical response in the series of patients treated with chemotherapy without bevacizumab. Conclusions: Notwithstanding the limited power of the present analysis, these data seem to suggest that low Notch expression might be a marker for successful bevacizumab treatment.

Adenomatous polyposis coli gene involvement in ileal enterochromaffin cell neuroendocrine neoplasms

The adenomatous polyposis coli gene is a key tumor suppressor gene. Alterations in this gene have been found in most sporadic colon cancers; associated with familial adenomatous polyposis; and found in neoplasms of other organs, such as the liver, stomach, lung, breast, and cerebellar medulloblastoma. In the heterogeneous group of neuroendocrine neoplasms of the gastrointestinal tract, the involvement of adenomatous polyposis coli is debated, and only occasional reports found adenomatous polyposis coli alterations in foregut and midgut neuroendocrine neoplasms, with adenomatous polyposis coli mutations only in the latter. To elucidate the penetrance of adenomatous polyposis coli alterations in ileal neuroendocrine neoplasms, we performed DNA fragment analysis (loss of heterozygosity for 5q22-23 and 5q23) and sequencing on the mutation cluster region of the adenomatous polyposis coli gene on 30 ileal enterochromaffin cell neuroendocrine neoplasms. Adenomatous polyposis coli gene mutations were detected in 23% of cases (7/30); in particular, 57% were missense and 14%, nonsense/frameshift, all novel and different from those reported in colorectal or other cancers. Loss of heterozygosity analysis demonstrated a deletion frequency of 15% (4/27). No association was found with features of tumor progression. Our observations support the involvement of somatic adenomatous polyposis coli alterations in tumorigenesis of ileal enterochromaffin cell neuroendocrine neoplasms; the mechanisms of adenomatous polyposis coli gene inactivation appear to be different from those reported in other tumor types.

Thymidylate synthase, topoisomerase-1 and microsatellite instability: relationship with outcome in mucinous colorectal cancer treated with fluorouracil

BACKGROUND

Mucinous colorectal cancer (CRC) exhibits distinct clinical and pathological features, including poorer response to fluorouracil (FU) compared with non-mucinous tumours.

PATIENTS AND METHODS

We compared the expression of thymidylate synthase (TYMS) and topoisomerase-1 (TOPO1) and DNA microsatellite instability (MSI) in 87 patients (35 mucinous and 52 non-mucinous CRCs) enrolled in three randomized trials, evaluating infused FU as first-line treatment.

RESULTS

Mucinous CRCs more frequently had high TOPO1 expression than did non-mucinous tumors (41% vs. 15%, p=0.028). The median overall survival was 14.2 months for patients with mucinous CRC with low TOPO1 expression compared with 9.7 months for high TOPO1-expressing cases (p=0.016). After adjusting for confounding variables, low TOPO1 expression was statistically favourably associated with overall survival (hazard ratio=0.55; p=0.041).

CONCLUSION

Our data suggest the TOPO1 expression levels to be a prognostic marker in patients with mucinous CRC treated with FU. If further verified, these data might redefine therapeutic strategies by identifying categories of patients with a worse prognosis.

Primary squamous cell carcinoma of the endometrium unrelated to human papilloma virus: a molecular study

In this paper we report a molecular study of a case of Primary Endometrial Squamous Carcinoma (PESC), in which a Human Papilloma Virus (HPV) infection had been previously excluded by Polymerase Chain Reaction (PCR). The studies performed in an effort to explain the carcinogenesis included immunohistochemical over-expression of p53 and p16 proteins as previously observed in our own papers, plus microsatellite analysis of D10S1765 at 10q23.3 (PTEN) and TP53 at 17p13.1 (P53) as well as the methylation status of the of BRCA1 and p16 promoters using specific PCRs. In this rare malignancy, we found allelic imbalance (AI) at 17p13.1 (P53). Instead, AI at D10S1765 (PTEN) gene was absent. The genetic alteration of p53, with hyper-expression of p53 protein and an absence of abnormalities in the PTEN gene are consistent with the similarities between Uterine Serous Carcinoma (USC) and our case of PESC. The aberrant methylation of both p16 and BCAR1 promoters was not detected in our case. This finding too could imply that ESC is more similar to Uterine Serous Carcinoma than Uterine Endometrioid Carcinoma (UEC). Moreover, the lack of aberrant methylation of p16, which is in accordance with over-expression of p16 immunoreactivity, in the absence of HPV infection may be related to other unknown genetic alterations. In our opinion, it is hard to reach any definite conclusion concerning the carcinogenesis of PESC, because of its rarity and the very few molecular studies reported in the literature. Further studies with more numerous cases and larger molecular analyses are mandatory for this malignancy, to confirm whether it is more closely related to papillary endometrial cancer than to endometrioid carcinoma.

Reliability of EGFR and KRAS mutation analysis on fine-needle aspiration washing in non-small cell lung cancer

INTRODUCTION

Molecular profiling of advanced non-small cell lung cancer (NSCLC) has become essential for predicting customized medical treatment decision. In light of recent advances in non-invasive diagnostic procedures in NSCLC, we aimed to demonstrate the reliability of assessing molecular tests for epidermal growth factor receptor (EGFR) and KRAS genes on cytological samples by comparing the molecular profile obtained on cells from scraped smears with that on paired needle washing in a series of NSCLC cases.

METHODS

Thirty-two cytological specimens obtained by fine-needle aspiration biopsy procedures from primary or metastatic lesions of NSCLCs were Giemsa stained for a rapid on-site evaluation and, in case of an adequate sampling, the cellular material obtained from needle washing was collected into a saline solution. Scraped smears and needle washings were tested for EGFR and KRAS by polymerase chain reaction followed by direct sequencing.

RESULTS

The concordance between EGFR and KRAS mutational status in 29 paired scraped smears and needle washing was 100%, with 7 paired samples showing the same EGFR mutation (4 L858R mutation, 2 E746_A750 deletion and 1 A767_V769 duplication) and 8 paired samples showing the same KRAS mutations (4 G12D, 1 G12A, 1 G12V and 2 G12C). Three scraped smears, uninformative for poor DNA quality, resulted EGFR mutated on paired needle washings.

CONCLUSIONS

Needle washing obtained in the course of NSCLC non-invasive fine needle diagnostic procedures allows reliable mutation testing and can be regarded as an additional important source of biological material for molecular profiling of advanced NSCLC.

Epidermal growth factor receptor and Kras gene expression: reliability of mutational analysis on cytological samples

Epidermal growth factor receptor (EGFR) and Kras gene mutations are crucial for discriminating patients responsive to anti-EGFR drugs in non-small cell lung cancer (NSCLC) and colorectal cancer (CRC), respectively. The majority of NSCLCs come to clinical attention at an advanced stage when surgery is no longer recommended and a considerable number of them are diagnosed by cytology only. A large number of metastatic CRCs are also diagnosed by imaging and minimally invasive techniques such as fine-needle aspiration biopsy. Here, we report our experience in the mutation analysis of EGFR and Kras on cytological material obtained from superficial and deep lesions of NSCLC and CRC. Our series included 63 cytological specimens from primary or metastatic lesions of 42 NSCLCs and 21 CRCs. The cytological material was adequate for the mutation analysis in 39/42 (93%) NSCLCs and in 20/21(95%) CRCs. EGFR and Kras mutations were found in 9 (23%) and 9 (23%) NSCLC cases, respectively. Kras mutations were found in 9/20 (45%) CRC specimens. Histological samples from the primary tumors were available in 9/42 NSCLCs and in 17/21 CRCs. The agreement of EGFR and Kras mutational status in cytological vs. histological samples was 100% for NSCLC and 88% for CRC. Our results suggest that standard cytology provides adequate material for the assessment of EGFR and Kras mutational status in NSCLC and CRC patients and could be specifically indicated in patients not eligible for surgery but candidate to anti-EGFR therapy.

Repeated anastomotic recurrence of colorectal tumors: Genetic analysis of two cases

AIM: To investigate genetics of two cases of colorectal tumor local recurrence and throw some light on the etiopathogenesis of anastomotic recurrence.

METHODS: Two cases are presented: a 65-year-old female receiving two colonic resections for primary anastomotic recurrences within 21 mo, and a 57-year-old female undergoing two local excisions of recurrent anastomotic adenomas within 26 mo. A loss of heterozygosity (LOH) study of 25 microsatellite markers and a mutational analysis of genes BRAF, K-RAS and APC were performed in samples of neoplastic and normal colonic mucosa collected over the years.

RESULTS: A diffuse genetic instability was present in all samples, including neoplastic and normal colonic mucosa. Two different patterns of genetic alterations (LOH at 5q21 and 18p11.23 in the first case, and LOH at 1p34 and 3p14 in the second) were found to be associated with carcinogenesis over the years. A role for the genes MYC-L (mapping at 1p34) and FIHT (mapping at 3p14.2) is suggested, whereas a role for APC (mapping at 5q21) is not shown.

CONCLUSION: The study challenges the most credited intraluminal implantation and metachronous carcinogenesis theories, and suggests a persistent, patient-specific alteration as the trigger of colorectal cancer anastomotic recurrence.

Involvement of HER-2/neu and metastasis-related proteins in the development of ileal neuroendocrine tumors

HER-2/neu overexpression and/or gene amplification occurs in several human malignancies, frequently correlates with tumor aggressiveness, and provides the basis for treatment with trastuzumab. Among neuroendocrine neoplasms (NEN) of the gastroenteropancreatic (GEP) tract, ileal neuroendocrine tumors show peculiar features of malignancy with frequent metastases at the diagnosis. We investigated the overexpression and/or amplification of HER-2/neu and the involvement of the metastasis-related proteins c-Met, MTA-1, and VEGF in 24 primary ileal NEN by immunohistochemistry and fluorescence in situ hybridization (FISH). Data were compared with those of 43 GEP endocrine tumors of other sites. All primary ileal NEN showed an intense membranous and cytoplasmic immunostaining for HER-2/neu. According to the breast cancer scoring system, 17% of ileal carcinoids showed a score of 3+ and 71% with a score of 2+ with a significant difference respect the non-ileal GEP endocrine tumors (p < 0.0000). FISH analysis revealed chromosome 17 polysomy in 33% of 2+/3+ ileal tumors but not HER-2/neu gene amplification. The c-Met and MTA-1 but not VEGF were overexpressed in almost all ileal NEN, whereas VEGF presented more frequently a normal staining. The comparisons with the other GEP NEN demonstrated significant differences for all the three proteins (p < 0.0000, p < 0.0002, and p < 0.001, respectively). These findings suggest that in ileal NEN, HER-2/neu overexpression plays a role in the carcinogenetic process and by triggering the altered expression of c-Met and MTA-1, may activate the molecular pathway(s) promoting tumor progression and metastasis development. Ileal HER-2/neu overexpressing neuroendrocrine tumors may constitute potential candidates for target therapy with specific humanized monoclonal antibodies.

Adenomatous polyposis coli alteration in digestive endocrine tumours: correlation with nuclear translocation of beta-catenin and chromosomal instability

The role of Wnt pathway in digestive endocrine tumours is debated. The aim of this work is to investigate key players in Wnt pathway by a multimodal approach. Sixty cases (49 well-differentiated and 11 poorly differentiated) were investigated for methylation of adenomatous polyposis coli (APC) and E-cadherin promoters, the loss of heterozygosity (LOH) at APC locus and beta-catenin and E-cadherin expression by immunohistochemistry. Tumours showing altered beta-catenin localization were tested for beta-catenin and APC mutations. APC promoter methylation was restricted to gastroduodenal tumours (21 out of 59, 36%), prevalent in poorly differentiated carcinomas (P=0.042) and correlating with aggressive features (high histology grade, P<0.02; tumour death, P=0.026; high fractional allelic loss, P=0.002, in turn correlating with short survival, P=0.017). LOH at APC locus was found in 14 out of 53 cases (26%, 10 gastroduodenal and 4 colorectal), prevalent in poorly differentiated carcinomas (P=0.002) and correlating with histology grade (P=0.012). beta-catenin abnormal expression was found in 41 out of 54 cases (76%), with nuclear staining correlating with APC alteration (P=0.047) and short survival (P=0.006). APC, but not beta-catenin, gene mutations were found (7 out of 35 tumours), 4 of which in the midgut. E-cadherin promoter methylation was rarely detected (2 out of 52 cases), with cytoplasmic expression in 18 out of 43 cases (42%), not correlating with any clinico-pathological feature. In conclusion, Wnt pathway alterations, as represented by abnormal beta-catenin localization, are common events in digestive endocrine tumours, but only nuclear expression correlates with tumour aggressiveness. Though with different alteration mechanisms according to anatomical site, APC plays a major role in Wnt pathway activation and in determining the high chromosomal instability observed in aggressive endocrine carcinomas.

Human papilloma virus (HPV) status, p16INK4a, and p53 overexpression in epithelial malignant and borderline ovarian neoplasms

This investigation is the first to evaluate simultaneously human papilloma virus (HPV) status, p16(INK4a), and p53 immunoreactivity in epithelial ovarian neoplasms. The results were analyzed and correlated with histological type, histological grade, and survival of patients. Subtypes considered are papillary serous and mucinous. Polymerase chain reaction (PCR) analysis, performed in our previous study, had already demonstrated a small number of HPV-positive epithelial ovarian neoplasms. No significant correlation was found between the presence of HPV DNA and subtypes of ovarian neoplasms; thus, HPV cannot be considered responsible for epithelial ovarian neoplasm. Since p16 immunoreactivity was present in many other HPV-negative cases of epithelial ovarian neoplasms, this study suggests that p16 overexpression in some neoplasms of the female genital tract is not related to HPV carcinogenesis. A higher p53 expression rate observed between borderline and malignant serous tumors and between serous and mucinous neoplasms can confirm a recent dualistic model of ovarian carcinogenesis. According to this theory, low-grade serous carcinomas (serous intraepithelial carcinomas, serous borderline neoplasm, and ovarian mucinous neoplasms) (type I tumors) develop from mutations of KAS and BRAF, while high-grade serous carcinomas (type II tumors) develop from mutation of p53. In malignant neoplasms, for univariate analysis, patient survival seems to be related to p53, strong and diffuse p16 overexpression, and the stage of development of neoplasms at the diagnosis. In multinomial logistic regression, used to evaluate the role of staging, grading, p16 and p53 immunopositivity as predictor variables of unfavorable outcome of the disease, only p16 positivity was significantly related to the poor prognosis of the cancer.

Sex chromosome alterations associate with tumor progression in sporadic colorectal carcinomas

PURPOSE

The X and Y chromosomes have been associated with malignancy in different types of human tumors. This study attempts to determine the involvement of X chromosome and pseudoautosomal regions (PAR) in sporadic colorectal carcinogenesis.

EXPERIMENTAL DESIGN

An allelotyping of X chromosome in 20 premalignant and 22 malignant sporadic colorectal tumors (CRC) from female patients and an analysis of losses [loss of heterozygosity (LOH)] on PARs from 44 CRCs and 12 adenomas of male patients were carried out. In male tumors, a fluorescence in situ hybridization analysis was done to identify which sex chromosome was possibly lost.

RESULTS

The LOH frequency in female CRCs was 46% with higher incidence in patients with tumor recurrence than in those who were disease-free (P < 0.01) and with a significant difference from adenomas (11%; P < 0.0001). The LOH rate of PARs in male CRCs was 37% with a frequency significantly higher in patients with recurrence (P < 0.03). These results were maintained also when data from PARs of all 66 male and female patients were cumulated (P < 0.05). LOH in PARs was significantly correlated with LOH at 5q (P < 0.01) and 18q (P < 0.01), early and late events, respectively, in colorectal carcinogenesis. Fluorescence in situ hybridization analysis in male patients with extensive PAR LOH revealed a preferential loss of the Y chromosome.

CONCLUSIONS

Our data suggest a role for sex chromosome deletions in the malignant progression of sporadic CRCs and support the presence in the PARs of putative tumor suppressor genes involved in the progression of human sporadic CRCs.

P16INK4a overexpression independent of Human Papilloma Virus (HPV) infection in rare subtypes of endometrial carcinomas

In the current study, we evaluated p16 expression in rare subtypes of endometrial carcinomas, whose HPV status has been previously examined in order to establish the role of this protein in their pathogenesis. These rare subtypes of endometrial carcinomas are primary squamous endometrial carcinoma (ESCC), endometrial mucinous microglandular adenocarcinoma (EMMA), and endometrial transitional cell carcinoma (ETCC). All tissues, obtained at the time of hysterectomy, were fixed in 10% phosphate-buffered formalin and embedded in paraffin. Serial sections were made for hematoxylin and eosin staining and for immunohistochemistry. Although a previous PCR study has demonstrated that none of these neoplasms showed any signal for HPV DNA, these malignancies did display immunoreactivity for P16(INK4a). In ESCC, P16(INK4a) immunoreactivity was diffuse in 100% of neoplastic cells. In two cases of EMMA, positivity for P16INK4a was zonal. In ETCC, scattered cells were positive for P16INK4a protein. These findings suggest that alteration of p16 could play an etiologic role, without any association to HPV infections, in these rare endometrial carcinomas. However, in our view, other cases of these rare malignancies should be investigated in order to confirm this hypothesis.

Peptide products of the neurotrophin-inducible gene vgf are produced in human neuroendocrine cells from early development and increase in hyperplasia and neoplasia

BACKGROUND

Although the neurotrophin-inducible gene vgf is expressed in mammalian neurons and endocrine cells, limited data is available in man.

AIM

The objective of the study was to map proVGF peptides in human endocrine cells during development, adulthood, hyperplasia, and tumors.

METHODS

Antisera were generated against peptides related to internal cleavage or cleavage-amidation sites (rat proVGF(422-430) and human proVGF(298-306)-NH2) and the proVGF C-terminal ending (human proVGF(607-615)). Developing and normal adult endocrine cells, hyperplastic endocrine lesions (thyroid, parathyroid, lung, and stomach), and 120 tumors (102 endocrine) were studied. Immunogold electron microscopy was performed on normal adult pancreas and gut, and Western blotting was performed on extracts of control tissues and endocrine tumors.

RESULTS

proVGF fragments were revealed in developing pituitary, gut, pancreas, and adrenal medulla from 10 gestational weeks, in normal adult pituitary and adrenal medulla, pancreatic glucagon, and insulin cells and gut serotonin cells, in hyperplastic thyroid calcitonin cells, lung P cells, gastric enterochromaffin-like cells, and gastrin cells, and in 88 of 102 endocrine tumors. At electron microscopy proVGF immunoreactivity was restricted to electron-dense granules. Western blotting revealed large molecular weight forms and cleavage fragments in both control tissues and tumor extracts.

CONCLUSIONS

proVGF-related peptides are present in endocrine cells early during development and adulthood and increase in hyperplasia and tumors, and proVGF fragments could be novel diagnostic tools for endocrine cells and related lesions, including tumors.

Loss of p27 expression and microsatellite instability in sporadic colorectal cancer

BACKGROUND

The role of the loss of p27 protein expression in the oncogenesis of colorectal cancer is still in debate. In this study, we prospectively examined the immunohistochemical expression of p27 in 108 consecutive colorectal cancers, and we analysed the relationship with the results, the clinicopathological data, microsatellite instability (MSI) and other genetic alterations of tumours.

METHODS

Unselected patients (108) who underwent curative colorectal resection for sporadic colorectal cancer in a three-year period were evaluated for MSI using 6 microsatellite markers, and for the presence of p27, p53, Fhit, Mlh1 and Msh2 proteins by means of immunostaining. The relationships between these markers were analysed. p27 protein expression was examined for association with disease recurrences and survival.

RESULTS

Lack of p27 expression was noted in 33 out of 108 (30.5%) colorectal cancer cases (P<0.05). This altered expression was significantly higher in proximal cancers (P<0.05), mucinous tumours (P<0.001), poorly differentiated histology (P<0.01), cancers with MSI (P<0.05), tumours with altered expression of Mlh1 (P<0.01), of Msh2 (P<0.05), and of Fhit (P<0.01). Overall survival was better in the patient group with altered level of phenotypic p27 expression, although the difference does not reach statistical significance (P=0.069). The analysis performed only for patients with tumour at stage II showed significantly better survival when the tumour exhibited altered p27 expression (P<0.02).

CONCLUSIONS

The results of the present study support the hypothesis that altered expression of p27 may be part of the genetic pathway involving MSI, which is responsible for the development of some colorectal cancers.

Distinct molecular patterns based on proximal and distal sporadic colorectal cancer: arguments for different mechanisms in the tumorigenesis

BACKGROUND AND AIMS

Colorectal cancer (CRC) ranks as the fourth most frequently diagnosed cancer worldwide. CRCs that arise proximally or distally to the splenic flexure show differences in epidemiologic incidence, morphology, and molecular alterations, suggesting the existence of two categories of CRC based on the site of origin. The aim of the present work is to investigate the histological and molecular differences between CRCs located proximally and distally to the splenic flexure, and their potential involvement in tumor prognosis and therapeutic strategies.

METHODS

We evaluated 120 patients affected by sporadic CRC for clinicopathologic features, microsatellite instability (MSI), loss of heterozygosity (LOH) of chromosomes 18q, 8p, and 4p; they were also investigated for hMlh1, hMsh2, Fhit, p27, and Cox-2 immunostaining.

RESULTS

The mucinous histotype was more frequent in the proximal than in the distal CRCs (p<0.004). The frequency of MSI phenotype was higher in proximal than in distal tumors (p<0.001); moreover, reduced or absent hMlh1, Fhit, p27 immunohistochemical expressions were more frequent in proximal than in distal tumors (p<0.001 and 0.01 for p27). In contrast, the frequency of LOH in 18q was higher in distal than in proximal tumors (p=0.002). No significant differences were observed between proximal and distal tumors in the frequency of LOH in 8p and altered expression of hMsh2 and p53 protein.

CONCLUSION

These different features may reflect different genetic pathways of carcinogenesis and support the hypothesis of a different mechanism of cancer development between the proximal and the distal colon, with potential implications in the therapeutic approach.