Loss of p27 expression and microsatellite instability in sporadic colorectal cancer

Loss of p27Kip1 leads to expansion of CD4+ effector memory T cells and accelerates colitis-associated colon cancer in mice with a T cell lineage restricted deletion of Smad4

The cyclin-dependent kinase inhibitor p27^Kip1 is a tumor suppressor whose intrinsic activity in cancer cells correlates with tumor aggressiveness, invasiveness, and impaired tumor cell differentiation. Here we explore whether p27^Kip1 indirectly influences tumor progression by restricting expansion and survival of effector memory T cell (T_EM) populations in a preclinical model of spontaneous colitis-associated colorectal cancer (CAC). We show mRNA and protein expression of p27^Kip1 to be significantly decreased in the colons of mice with a T cell-restricted deletion of the TGF-β intermediate, SMAD4 (Smad4^TKO). Loss of p27^Kip1 expression in T cells correlates with the onset of spontaneous CAC in Smad4^TKO mice by 8 months of age. This phenotype is greatly accelerated by the introduction of a germline deletion of CDKN1b (the gene encoding p27^Kip1) in Smad4^TKO mice (Smad4^TKO/p27^Kip1-/-, DKO). DKO mice display colon carcinoma by 3 months of age and increased mortality compared to Smad4^TKO. Importantly, the phenotype in DKO mice is associated with a significant increase in the frequency of effector CD4 T cells expressing abundant IFN-γ and with a concomitant decrease in Foxp3⁺ regulatory T cells, both in the intestinal mucosa and in the periphery. In addition, induction of inflammatory mediators (IFN-γ, TNF-γ, IL-6, IL-1β, iNOS) and activation of Stat1, Stat3, and IκB is also observed in the colon as early as 1–2 months of age. Our data suggest that genomic alterations known to influence p27^Kip1 abundance in gastrointestinal cancers may indirectly promote epithelial malignancy by augmenting the production of inflammatory mediators from a spontaneously expanding pool of T_EM cells.

Colorectal cancer screenings: a single center experience

AIM

evaluating the impact of screening programmes on colorectal cancer (CRC) in Italy.

METHODS

we studied 1292 patients with colorectal cancer. Data were collected from January 2004 through December 2015 in Parma University Hospital. We compared clinophatological features to evaluate the real impact of screening programmes on detecting early stage colorectal cancers in target population.

RESULTS

screening programmes with fecal occult blood test (FOBT) and colonoscopy covered only patients from 50 to 69. In our study we reported that the 52,3% of patients with CRC were over 70 and out of screen time, while only 47,7% were under 70. Early detection seems to be related to early stage of CRC and to an improved overall survival.

CONCLUSION

The importance of early detection in colorectal cancers represents the most important outcome for OS. The risk of colorectal cancer is increased in elderly. Actual screening programmes cover less than 50% of population with colorectal cancer. Screening should be considered for patients over 70, due to the high number of new diagnosis in symptomatic disease and worst prognosis, in accordance with advanced cancer stage and comorbidities in elderly.

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.

Surgical treatment of multiple sporadic colorectal carcinoma

Aim: Many aspects of the surgical management of multiple sporadic colorectal cancer syndrome, either synchronous and metachronous, remain to be cleared, in particular the prognostic influence of the extent of surgical resection. Method: A retrospective review was performed of patients diagnosed with multiple colorectal cancer from 1982 to May 2010. Clinical and pathologic data were collected and reviewed. Survival analysis was performed. Results: We identified 23 patients with multiple sporadic colorectal cancers, of which 8 had synchronous (SC) and 15 metachronous cancers (MC). Of the MC patients, 2 (13%) had the second cancer within 2 years, 4 (27%) in the time period of 2-5 years and 9 (60%) after 5 years. Twenty-one patients underwent multiple segmental resections; 2 patients underwent subtotal colectomy. The 5-year overall survival rate of SC and MC patients was 100% and 87% (p<0.001) respectively. The 5-year overall survival rate of multiple segmental resection patients and subtotal colectomy was 94% and 75% (p=0.655) respectively. Conclusion: Either synchronous and metachronous MSCRC patients showed good prognosis independently from to the extent of resection. Our results support a less aggressive biological behaviour allowing a more conservative management. Multiple segmental colorectal resections seem appropriate from an oncologic point of view in MSCRC patients. (www.actabiomedica.it)

The B56γ3 regulatory subunit-containing protein phosphatase 2A outcompetes Akt to regulate p27KIP1 subcellular localization by selectively dephosphorylating phospho-Thr157 of p27KIP1

The B56γ-containing protein phosphatase 2A (PP2A-B56γ) has been postulated to have tumor suppressive functions. Here, we report regulation of p27KIP1 subcellular localization by PP2A-B56γ3. B56γ3 overexpression enhanced nuclear localization of p27KIP1, whereas knockdown of B56γ3 decreased p27KIP1 nuclear localization. B56γ3 overexpression decreased phosphorylation at Thr157 (phospho-Thr157), whose phosphorylation promotes cytoplasmic localization of p27KIP1, whereas B56γ3 knockdown significantly increased the level of phospho-Thr157. In vitro, PP2A-B56γ3 catalyzed dephosphorylation of phospho-Thr157 in a dose-dependent and okadaic acid-sensitive manner. B56γ3 did not increase p27KIP1 nuclear localization by down-regulating the upstream kinase Akt activity and outcompeted a myristoylated constitutively active Akt (Aktca) in regulating Thr157 phosphorylation and subcellular localization of p27KIP1. In addition, results of interaction domain mapping revealed that both the N-terminal and C-terminal domains of p27 and a domain at the C-terminus of B56γ3 are required for interaction between p27 and B56γ3. Furthermore, we demonstrated that p27KIP1 levels are positively correlated with B56γ levels in both non-tumor and tumor parts of a set of human colon tissue specimens. However, positive correlation between nuclear p27KIP1 levels and B56γ levels was found only in the non-tumor parts, but not in tumor parts of these tissues, implicating a dysregulation in PP2A-B56γ3-regulated p27KIP1 nuclear localization in these tumor tissues. Altogether, this study provides a new mechanism by which the PP2A-B56γ3 holoenzyme plays its tumor suppressor role.

P27 expression in colorectal cancer: Significance and correlation with expression of Ki-67, P170, MLH1, MSH2, and MSH6

AIM: To investigate the relationship between P27 expression and tumor invasion, metastasis, multidrug resistance and prognosis of colorectal cancer (CRC), and to explore the possible mechanisms involved.

METHODS: Two hundred and sixty-three sporadic CRC patients who underwent surgery in the Department of Colorectal Surgery, Beijing Cancer Hospital from March 2008 to March 2012 were included in this study. All patients were diagnosed by histological examination and did not undergo chemoradiotherapy before surgery. Immunohistochemistry was used to detect P27, Ki-67, P170, MLH1, MSH2 and MSH6 protein expression in samples from these patients. The association between expression and clinical data was analysed retrospectively.

RESULTS: The positive rates of P27, Ki-67, P170, MLH1, MSH2 and MSH6 expression in CRC were 71.1%, 81.4%, 82.5%, 86.7%, 87.8% and 71.1%, respectively. Deficient expression of P27 was closely associated with tumour size, location, differentiation, invasion depth, vascular invasion and lymph node metastasis, but had no association with patients' gender, age, or tumor macroscopic morphology. P27 expression was negatively correlated with Ki-67 and P170 expression (r = -0.315, -0.163, P = 0.00, 0.01), but positively with MLH1, MSH2 and MSH6 expression (r = 0.129, 0.136, 0.159, P = 0.03, 0.03, 0.01).

CONCLUSION: P27 expression is closely associated with the development, invasion and metastasis of CRC. P27 protein expression can be regarded as an important parameter for evaluation of colorectal cancer progression and for selection of chemotherapy drugs and prevention of multidrug resistance.

Sporadic colorectal carcinomas with low-level microsatellite instability: a distinct subgroup with specific clinicopathological and molecular features

PURPOSE

The biologic significance of low-level microsatellite instability (MSI) in sporadic colorectal cancers (CRCs) is not clearly defined. In particular, the relationship of MSI-low to MSI-high and microsatellite stable (MSS) tumours is currently under debate and the prognostic impact of these genetic changes remains unclear. The objective of this study was to investigate whether sporadic MSI-low CRCs have different clinicopathological and molecular features from MSS and MSI-high tumours.

METHODS

A series of 184 primary sporadic CRCs were divided, according to the level of MSI, into three groups (94 MSS, 22 MSI-low and 68 MSI-high) and were analyzed for baseline clinicopathological features and outcome, allelic losses at 18q, 8p and 4p chromosomes and immunohistochemical expression of MGMT, hMlh1, hMsh2, Fhit, Cox-2, p21 and p27 proteins.

RESULTS

MSI-low tumours were more frequently distal (59.1%) whereas MSS tumours had a strong predilection for distal (72.3%) and MSI-high tumours for proximal location (54.4%; p = 0.003). When compared with MSI-high tumors, MSI-low CRCs were adenocarcinoma, not otherwise specified (p = 0.0138) and well to/moderately differentiated (p = 0.027). MSI-low CRCs also showed specific molecular features including intermediate 18q allelic losses, altered MGMT and Cox-2 expression. Finally, the 5-year overall survival rates were 79% for MSI-low, 40.3% for MSS and 71% for MSI-high CRCs (p = 0.0160 MSS vs. MSI-low groups).

CONCLUSIONS

Sporadic MSI-low CRCs display characteristic clinicopathological and genetic features that distinguish them from MSS CRCs.

A cohort study of p27 localization in colon cancer, body mass index, and patient survival

Energy balance and the AKT pathway are important in colorectal cancer development and regulate p27 (cyclin-dependent kinase inhibitor-1B/CDKN1B/KIP1), which plays a role in preventing cell cycle progression. However, little is known on the clinical outcome or prognostic significance of p27 alterations in relation to patient body mass index (BMI). Among 630 colon cancers (stage I-IV) in two prospective cohort studies, we detected p27 alterations (cytoplasmic p27 localization or p27 loss) in 500 tumors (79%) by immunohistochemistry. The remaining 130 (21%) tumors were "p27-nuclear+." Cox proportional hazard models computed hazard ratios (HR) of deaths, adjusted for patient and tumoral characteristics, including p53, p21, cyclin D1, KRAS, BRAF, PIK3CA, cyclooxygenase-2, fatty acid synthase (FASN), beta-catenin, microsatellite instability (MSI), CpG island methylator phenotype (CIMP), and long interspersed nucleotide element-1 (LINE-1) hypomethylation. Compared with p27-nuclear+ patients, p27-altered patients experienced low colon cancer-specific [adjusted HR, 0.63; 95% confidence interval (95% CI), 0.42-0.94] and overall mortality (adjusted HR, 0.70; 95% CI, 0.51-0.95), independent of FASN, MSI, CIMP, LINE-1 methylation, and other potential confounders. The effect of p27 alteration on overall mortality significantly differed by BMI (P(interaction) = 0.013); adjusted HR (p27-altered versus p27-nuclear+ tumors) was 0.28 (95% CI, 0.13-0.59) for BMI >or=30 kg/m(2), 0.67 (95% CI, 0.40-1.14) for BMI 25 to 29 kg/m(2), and 0.91 (95% CI, 0.57-1.46) for BMI <25 kg/m(2). Obesity was associated with inferior overall survival among p27-nuclear+ cases (adjusted HR, 3.07; 95% CI, 1.49-6.32; versus nonobese cases), but not among p27-altered cases (adjusted HR, 1.08). In conclusion, p27 alterations in colon cancer are associated with superior prognosis. Adverse prognostic effect of obesity seems limited to patients with nuclear p27 expression, suggesting a host-tumor interaction.

Clinical, pathologic, and molecular features of early-onset colorectal carcinoma

The incidence of colorectal carcinoma has increased among patients <40 years of age for unclear reasons. In this study, we describe the clinical, pathologic, and molecular features of colorectal carcinomas that developed in young patients. We compiled a study group of 24 patients <40 years of age with colorectal carcinoma, and 45 patients > or =40 years of age served as controls. Cases were evaluated for clinical risk factors of malignancy and pathologic features predictive of outcome. The tumors were immunohistochemically stained for O6-methylguanine methyltransferase, MLH-1, MSH-2, MSH-6, beta-catenin, chemokine (C-X-C motif) receptor 4, epidermal growth factor receptor, TP53, p16, survivin, and alpha-methylacyl-CoA racemase; assessed for microsatellite instability and mutations in beta-catenin, APC, EGFR, PIK3CA, KRAS, and BRAF; evaluated for micro-RNA expression (miR-21, miR-20a, miR-183, miR-192, miR-145, miR-106a, miR-181b, and miR-203); and examined for evidence of human papillomavirus infection. One study patient each had ulcerative colitis and hereditary nonpolyposis colorectal cancer. Ninety-two percent of tumors from young patients occurred in the distal colon (P=0.006), particularly the rectum (58%, P=0.02), and 75% were stage III or IV. Tumors from young patients showed more frequent lymphovascular (81%, P=0.03) and/or venous (48%, P=0.003) invasion, an infiltrative growth pattern (81%, P=0.03), and alpha-methylacyl-CoA racemase expression (83%, P=0.02) compared with controls. Carcinomas in this group showed significantly increased expression of miR-21, miR-20a, miR-145, miR-181b, and miR-203 (P< or =0.005 for all comparisons with controls). These results indicate that early-onset carcinomas commonly show pathologic features associated with aggressive behavior. Posttranslational regulation of mRNA and subsequent protein expression may be particularly important to the development of colorectal carcinomas in young patients.

Role of Cks1 amplification and overexpression in breast cancer

Gain of chromosome 1q is a common event in many kinds of carcinomas. The Cks1 gene, located at 1q21, is required for p27 ubiquitination by the SCF(skp2) ubiquitinating machinery. In the present study, we found that Cks1 gene amplification was highly correlated with protein overexpression. Statistical analysis showed that amplification and overexpression of Cks1 were strongly associated with lymph node metastasis and poor prognosis. At the molecular level, knockdown of Cks1 expression by RNA interference inhibited the growth of MDA-MB-231 cells, damaged cell migration and invasion ability. Knockdown of Cks1 expression promoted apoptosis of breast cancer cells and a wobble mutant of Cks1 that was resistant to Cks1 siRNA can rescue this effect. Overexpression of Cks1 inhibited the apoptosis of breast cancer cells through the MEK-Erk pathway. These data suggest that Cks1 is an oncogene in the 1q21 amplicon and plays an important role for breast cancer development.

The Cdk inhibitor p27 in human cancer: prognostic potential and relevance to anticancer therapy

The cyclin-dependent kinase (Cdk) inhibitor p27 (also known as KIP1) regulates cell proliferation, cell motility and apoptosis. Interestingly, the protein can exert both positive and negative functions on these processes. Diverse post-translational modifications determine the physiological role of p27. Phosphorylation regulates p27 binding to and inhibition of cyclin-Cdk complexes, its localization and its ubiquitin-mediated proteolysis. In cancers, p27 is inactivated through impaired synthesis, accelerated degradation and by mislocalization. Moreover, studies in several tumour types indicate that p27 expression levels have both prognostic and therapeutic implications.