Immunohistochemical determination of the P15 protein expression in cutaneous squamous cell carcinoma

Systematical analysis of cutaneous squamous cell carcinoma network of microRNAs, transcription factors, and target and host genes

BACKGROUND

MicroRNAs (miRNAs) are small non-coding RNA molecules found in multicellular eukaryotes which are implicated in development of cancer, including cutaneous squamous cell carcinoma (cSCC). Expression is controlled by transcription factors (TFs) that bind to specific DNA sequences, thereby controlling the flow (or transcription) of genetic information from DNA to messenger RNA. Interactions result in biological signal control networks.

MATERIALS AND METHODS

Molecular components involved in cSCC were here assembled at abnormally expressed, related and global levels. Networks at these three levels were constructed with corresponding biological factors in term of interactions between miRNAs and target genes, TFs and miRNAs, and host genes and miRNAs. Up/down regulation or mutation of the factors were considered in the context of the regulation and significant patterns were extracted.

RESULTS

Participants of the networks were evaluated based on their expression and regulation of other factors. Sub-networks with two core TFs, TP53 and EIF2C2, as the centers are identified. These share self-adapt feedback regulation in which a mutual restraint exists. Up or down regulation of certain genes and miRNAs are discussed. Some, for example the expression of MMP13, were in line with expectation while others, including FGFR3, need further investigation of their unexpected behavior.

CONCLUSIONS

The present research suggests that dozens of components, miRNAs, TFs, target genes and host genes included, unite as networks through their regulation to function systematically in human cSCC. Networks built under the currently available sources provide critical signal controlling pathways and frequent patterns. Inappropriate controlling signal flow from abnormal expression of key TFs may push the system into an incontrollable situation and therefore contributes to cSCC development.

Loss of p15INK⁴b expression in colorectal cancer is linked to ethnic origin

Colorectal cancers remain to be a common cause of cancer-related death. Early-onset cases as well as those of various ethnic origins have aggressive clinical features, the basis of which requires further exploration. The aim of this work was to examine the expression patterns of p15INK4b and SMAD4 in colorectal carcinoma of different ethnic origins. Fifty-five sporadic colorectal carcinoma of Egyptian origin, 25 of which were early onset, and 54 cancers of Finnish origin were immunohistochemically stained with antibodies against p15INK4b and SMAD4 proteins. Data were compared to the methylation status of the p15INK4b gene promotor. p15INK4b was totally lost or deficient (lost in ≥ 50% of tumor cell) in 47/55 (85%) tumors of Egyptian origin as compared to 6/50 (12%) tumors of Finnish origin (p=7e-15). In the Egyptian cases with p15INK4b loss and available p15INK4b promotor methylation status, 89% of cases which lost p15INK4b expression were associated with p15INK4b gene promotor hypermethylation. SMAD4 was lost or deficient in 25/54 (46%) tumors of Egyptian origin and 28/48 (58%) tumors of Finnish origin. 22/54 (41%) Egyptian tumors showed combined loss/deficiency of both p15INK4b and SMAD4, while p15INK4b was selectively lost/deficient with positive SMAD4 expression in 24/54 (44%) tumors. Loss of p15INK4b was associated with older age at presentation (>50 years) in the Egyptian tumors (p=0.04). These data show for the first time that p15INK4b loss of expression marks a subset of colorectal cancers and ethnic origin may play a role in this selection. In a substantial number of cases, the loss was independent of SMAD4 but rather associated with p15INK4b gene promotor hypermethylation and old age which could be related to different environmental exposures.

Promoter hypermethylation of p14 (ARF) , RB, and INK4 gene family in hepatocellular carcinoma with hepatitis B virus infection

Both hepatitis B virus (HBV) and gene methylation play important roles in hepatocarcinogenesis. However, their association between HBV infection and gene methylation is not fully understood. Cell cycle control involving RB1 gene-related cell inhibitors is one of the main regulatory pathways were reported to be altered in hepatocellular carcinoma (HCC). The purpose of this research is to assess the methylation status of p14 (ARF) and INK4 gene family (p14 (ARF) , p15 (INK4B) , p16 (INK4A) , and p18 (INK4C) ) in HCC with HBV infection and HCC without it, and discuss possible role of HBV-induced hypermethylation in the mechanism of hepatocarcinogenesis. Methylation status of RB, p14 (ARF) , and INK4 gene family in 64 case of HCC with HBV infection and 24 cases without it were detected by methylation-specific polymerase chain reaction, and HBV-DNA of the plasma were detected by quantitative real-time polymerase chain reaction. p14 (ARF) , p15 (INK4B) , p16 (INK4A) , and RB hypermethylation were observed in 30 (34.1%), 50 (56.8%), 62 (70.5%), and 24(27.3%) of 88 hepatocellular carcinomas, respectively. Methylation frequencies of them between HCC with HBV infection and HCC without it were 43.8% versus 8.3 % (p14 (ARF) ), 68.9% versus 25% (p15 (INK4B) ), 90.6% versus 16.7% ( p16 (INK4A) ), and 28.1 % versus 25% (RB), respectively. In HBV-associated HCC, the numbers of methylated genes were also more than HCC without virus infection, more than two methylated genes were seen in 48 of 64 (75 %) cases; more than three methylated genes were found in 32 of 64 (50%); correspondently, no one case has more than two genes methylated. p18 (INK4C) methylation product was not found in cancerous or non-cancerous tissues of 88 HCC. HBV infection is associated with p14 (ARF) , p15 (INK4B) , p16 (INK4A) , and RB gene methylation (P = 0.048, 0.035, 0.02); HBV-DNA replication is associated with p14 (ARF) , p15 (INK4B) , p16 (INK4A) , and RB gene methylation (P = 0.048, 0.035, 0.02); high rate of p14 (ARF) , p15 (INK4B) , and p16 (INK4A) in HCC with HBV infection suggests that HBV-induced hypermethylation may be one of the mechanisms of HBV involved in hepatocellular carcinogenesis.

Ocular expression and distribution of products of the POAG-associated chromosome 9p21 gene region

It has recently been shown that there are highly significant associations for common single nucleotide polymorphisms (SNPs) near the CDKN2B-AS1 gene region at the 9p21 locus with primary open angle glaucoma (POAG), a leading cause of irreversible blindness. This gene region houses the CDKN2B/p15^INK4B_,CDKN2A/p16^INK4A and p14ARF (rat equivalent, p19^ARF) tumour suppressor genes and is adjacent to the S-methyl-5′-thioadenosine phosphorylase (MTAP) gene. In order to understand the ocular function of these genes and, therefore, how they may be involved in the pathogenesis of POAG, we studied the distribution patterns of each of their products within human and rat ocular tissues. MTAP mRNA was detected in the rat retina and optic nerve and its protein product was localised to the corneal epithelium, trabecular meshwork and retinal glial cells in both human and rat eyes. There was a very low level of p16^INK4A mRNA present within the rat retina and slightly more in the optic nerve, although no protein product could be detected in either rat or human eyes with any of the antibodies tested. P19^ARF mRNA was likewise only present at very low levels in rat retina and slightly higher levels in the optic nerve. However, no unambiguous evidence was found to indicate expression of specific P19^ARF/p14^ARF proteins in either rat or human eyes, respectively. In contrast, p15^INK4B mRNA was detected in much higher amounts in both retina and optic nerve compared with the other genes under analysis. Moreover, p15^INK4B protein was clearly localised to the retinal inner nuclear and ganglion cell layers and the corneal epithelium and trabecular meshwork in rat and human eyes. The presented data provide the basis for future studies that can explore the roles that these gene products may play in the pathogenesis of glaucoma and other models of optic nerve damage.

Lack of increased P15INK4B protein expression in basal cell carcinomas

BACKGROUND

The basal cell carcinoma (BCC) is the most common non-melanoma skin cancer (NMSK). BCC might develop because of the faulty cell cycle arrest. P15INK4b is a tumor suppressor gene, involved in cell cycle arrest and inactivated in most human cancers. The role of p15INK4b protein expression in the genesis of BCC is as yet unknown. In a previous study we showed the absence of p15INK4b expression in the majority of tissue microarray cores of cutaneous squamous cell carcinoma (SCCs), another type of non-melanoma skin cancer, indicating that p15INK4b could possibly be involved in the pathogenesis of cutaneous SCC. The aim of this study was to investigate p15INK4b protein expression in BCCs.

MATERIALS AND METHOD

Protein expression of p15INK4b in 35 cases of BCC tissue arrays and 19 cases of normal human skin tissue was studied using an immunohistochemical approach.

RESULTS

The expression of p15INK4b was not significantly different in the BCC cases as compared with normal human skin (p=0.356; p>0.05). In addition, there were no significant relationship between clinicopathologic variables of patients (age and sex) and p15INK4b protein expression.

CONCLUSIONS

Our finding may indicate that p15INK4b protein expression does not play a role in the genesis of BCC.