Effects of aging and caloric restriction on IGF-I, IGF-I receptor, IGFBP-3 and IGFBP-4 gene expression in the rat stomach and colon

Comprehensive Analysis of Copy Number Variations in Kidney Cancer by Single-Cell Exome Sequencing

Clear-cell renal cell carcinoma (ccRCC) is the most common and lethal subtype of kidney cancer. VHL and PBRM1 are the top two significantly mutated genes in ccRCC specimens, while the genetic mechanism of the VHL/PBRM1-negative ccRCC remains to be elucidated. Here we carried out a comprehensive analysis of single-cell genomic copy number variations (CNVs) in VHL/PBRM1-negative ccRCC. Genomic CNVs were identified at the single-cell level, and the tumor cells showed widespread amplification and deletion across the whole genome. Functional enrichment analysis indicated that the amplified genes are significantly enriched in cancer-related signaling transduction pathways. Besides, receptor protein tyrosine kinase (RTK) genes also showed widespread copy number variations in cancer cells. Our studies indicated that the genomic CNVs in RTK genes and downstream signaling transduction pathways may be involved in VHL/PBRM1-negative ccRCC pathogenesis and progression, and highlighted the role of the comprehensive investigation of genomic CNVs at the single-cell level in both clarifying pathogenic mechanism and identifying potential therapeutic targets in cancers.

ADAM28 is expressed by epithelial cells in human normal tissues and protects from C1q-induced cell death

ADAM28 (disintegrin and metalloproteinase 28), which was originally reported to be lymphocyte-specific, is over-expressed by carcinoma cells and plays a key role in cell proliferation and progression in human lung and breast carcinomas. We studied ADAM28 expression in human normal tissues and examined its biological function. By using antibodies specific to ADAM28, ADAM28 was immunolocalized mainly to epithelial cells in several tissues, including epididymis, bronchus and stomach, whereas lymphocytes in lymph nodes and spleen were negligibly immunostained. RT-PCR, immunoblotting and ELISA analyses confirmed the expression in these tissues, and low or negligible expression by lymphocytes was found in the lymph node and spleen. C1q was identified as a candidate ADAM28-binding protein from a human lung cDNA library by yeast two-hybrid system, and specific binding was demonstrated by binding assays, immunoprecipitation and surface plasmon resonance. C1q treatment of normal bronchial epithelial BEAS-2B and NHBE cells, both of which showed low-level expression of ADAM28, caused apoptosis through activation of p38 and caspase-3, and cell death with autophagy through accumulation of LC3-II and autophagosomes, respectively. C1q-induced cell death was attenuated by treatment of the cells with antibodies against the C1q receptor gC1qR/p33 or cC1qR/calreticulin. Treatment of C1q with recombinant ADAM28 prior to addition to culture media reduced C1q-induced cell death, and knockdown of ADAM28 using siRNAs increased cell death. These data demonstrate that ADAM28 is expressed by epithelial cells of several normal organs, and suggest that ADAM28 plays a role in cell survival by suppression of C1q-induced cytotoxicity in bronchial epithelial cells.

[Age-related microscopic and molecular changes of the human colon, and their role in the development of colorectal cancer in elderly people]

The gastrointestinal effect of aging, the recognition of its molecular background and the mapping its connections with several diseases like sporadic colorectal cancer of elder people are a new and promising area of molecular gastroenterology. Nowadays, it is a well-known fact that some age-related molecular changes (e.g.: DNA methylation, telomere shortening) can be detected in several types of colorectal cancers. The known epidemiologic and molecular biologic features of sporadic colorectal cancer are not enough to explain the genetic, gene expression or epigenetic changes that may be involved in the increase of the disease over 45-50 age years. The connections of these alterations to the process of aging are also unclear. The understanding and custom-tailored modification of these mechanisms are of great clinical importance regarding of prevention and modern therapeutic strategies. In this review, we aimed to summarize the age-related microscopic and molecular changes of the human colon, as well as their role in the development of colorectal cancer of the elder people.

Induction of MMP-1 (collagenase-1) by relaxin in fibrocartilaginous cells requires both the AP-1 and PEA-3 promoter sites

OBJECTIVES - Relaxin induces the matrix metalloproteinase MMP-1 (collagenase-1) in TMJ fibrocartilaginous cells, and this response is potentiated by beta-estradiol. We identified the MMP-1 promoter sites and transcription factors that are induced by relaxin with or without beta-estradiol in fibrocartilaginous cells. MATERIAL AND METHODS - Early passage cells were transiently transfected with the pBLCAT2 plasmid containing specific segments of the human MMP-1 promoter regulating the chloramphenicol acyl transferase (CAT) gene and co-transfected with a plasmid containing the beta-galactosidase gene. The cells were cultured in serum-free medium alone or medium containing 0.1 ng/ml relaxin, or 20 ng/ml beta-estradiol or both hormones, and lysates assayed for CAT and beta-galactosidase activity. RESULTS - Cells transfected with the -1200/-42 or -139/-42 bp MMP-1 promoter-reporter constructs showed 1.5-fold and 3-fold induction of CAT by relaxin in the absence or presence of beta-estradiol, respectively. Relaxin failed to induce CAT in the absence of the -137/-69 region of the MMP-1 promoter, which contains the AP-1-and PEA3-binding sites. Using wild type or mutated minimal AP-1 and PEA-3 promoters we found that both these promoter sites are essential for the induction of MMP-1 by relaxin. The mRNAs for transcription factors c-fos and c-jun, which together form the AP-1 heterodimer, and Ets-1 that modulates the PEA-3 site, were upregulated by relaxin or beta-estradiol plus relaxin. CONCLUSION - These studies show that both the AP-1 and PEA-3 promoter sites are necessary for the induction of MMP-1 by relaxin in fibrocartilaginous cells.

Insulin resistance, apoptosis, and colorectal adenoma risk

Compelling evidence from epidemiologic studies indicates that elevated circulating insulin-like growth factor (IGF)-I, insulin resistance, and associated complications, such as elevated fasting plasma insulin, glucose and free fatty acids, glucose intolerance, increased body mass index, and visceral adiposity, are linked with increased risk of colorectal cancer. However, the role of insulin and markers of glucose control in the development of adenomas, precursors to colorectal cancer, has not been fully explored. We evaluated the relationship between plasma insulin, glucose, IGF-I, IGF-II, IGF-binding protein-3 (IGFBP-3), apoptosis, and colorectal adenomas in a case-control study. Participants were drawn from consenting patients undergoing colonoscopy at the University of North Carolina hospitals (Chapel Hill, NC). Participants were classified as cases or controls based on whether they had one or more colorectal adenomatous polyps. Fasting plasma insulin, IGF-I, IGF-II, and IGFBP-3 levels were assessed by ELISA. Glucose was measured by glucose hexokinase assay. Apoptosis was assessed by morphology on H&E-stained sections. Dietary and lifestyle information were obtained by telephone interview. Logistic regression was used to examine the association between adenoma status and insulin-IGF markers. Adenoma cases (n = 239) and adenoma-free controls (n = 517) provided rectal biopsies and/or blood samples and interview data. Consistent with prior findings, cases were more likely to be males, older, have higher waist-to-hip ratio, lower calcium intake, lower apoptosis, and less likely to report nonsteroidal anti-inflammatory drug use. Those in the highest quartile of insulin (adjusted odds ratio, 2.2; 95% confidence interval, 1.1-4.2) and glucose (adjusted odds ratio, 1.8; 95% confidence interval, 0.9-3.6) were more likely to have an adenoma compared with the lowest quartile. Similarly, subjects in the highest two quartiles of insulin were more likely to be in the lowest two quartiles of apoptosis. Overall, there were no significant differences between mean circulating levels of glucose, IGF-I, IGF-II, and IGFBP-3 among cases and controls and no association between these variables and apoptosis. The results provide novel evidence that elevated insulin and glucose are associated with increased adenoma risk and decreased apoptosis in normal rectal mucosa. These findings suggest that insulin may act early in the adenoma-carcinoma sequence to promote the development of colorectal adenoma by decreasing apoptosis in the normal mucosa.

Gene expression changes reveal patterns of aging in the rat digestive tract

Similarly to other organs, the human digestive system is adversely affected by aging presenting physiologic manifestations that include compromised absorption and secretion, decreased motility, weakened mucosal barrier and as well as a high incidence of colon cancer. As biomedical advances enable the population to live longer, our understanding of molecular events that govern aging and disease states is enhanced through methodical analyses of temporal tissue-specific gene expression profiles. Recently, DNA microarray analyses have been employed to examine age-associated transcriptional profiles in the mammalian digestive tract. Gene expression patterns revealed that the magnitude and trend of age-associated changes differ in the rat colon and duodenum. Interestingly, the expression of genes involved in energy-generating metabolic pathways was decreased in the duodenum and increased in the colon. Microarray analyses detected modulations in expression of genes associated with compromised intestinal function and propensity for colon cancer in the aged population. Furthermore, altered expression was observed for certain genes implicated in governance of aging and lifespan in other organisms suggesting intriguing commonalities across species. Thus, these studies demonstrated feasibility and usefulness of DNA microarrays for identifying pathways involved in the molecular pathophysiology of the aging process and lifespan control in complex organisms.

Effects of caloric restriction on cell proliferation in several tissues in mice: role of intermittent feeding

Reduced cell proliferation may mediate anticarcinogenic effects of caloric restriction (CR). Using heavy water (2H2O) labeling, we investigated the cell proliferation response to CR in detail, including time course, effect of refeeding, and role of intermittent feeding with 5% CR. In the time-course study, 8-wk-old female C57BL/6J mice were placed on a 33% CR regimen (fed 3 times/wk) for varying durations. Compared with responses in controls fed ad libitum (AL), proliferation rates of keratinocytes, mammary epithelial cells, and T cells were markedly reduced within 2 wk of CR. In mice fed 95% ad libitum (C95, fed 3 times/wk), cell proliferation was also reduced in all tissues so that differences from 33% CR were only significant at 1 mo. In the refeeding study, mice were refed a C95 diet for varying durations after 1 mo of 33% CR. Cell proliferation rebounded to a suprabasal rate in all tissues after 2 wk of refeeding and then normalized after 2 mo, although the C95 group again exhibited lower cell proliferation than the AL group. The role of intermittent feeding was studied by comparing 33% CR and C95 animals (both fed intermittently) with animals fed isocalorically either daily or continuously by pellet dispenser. Intermittent feeding had no additive effect on 33% CR but reduced cell proliferation in all tissues at the 95% caloric intake level. In summary, the CR effect on cell proliferation is potent, rapid, and reversible in several tissues, and an intermittent feeding pattern reproduces much of the effect in the absence of substantial CR.

The role of the insulin-like growth factor system in colorectal cancer: review of current knowledge

BACKGROUND

The insulin-like growth factor system, which includes insulin-like growth factors (IGF-I and IGF-II), IGF receptors (IGF-IR and IGF-IIR) and IGF binding proteins (IGFBPs), plays an important role in epithelial growth, anti-apoptosis and mitogenesis. There is a growing body of evidence showing that IGFs control growth and proliferation of several types of cancer. This review introduces the latest information on the biology of the IGF system and its pathophysiological role in the development of colorectal cancer.

DISCUSSION

The growth promoting effects of IGF-I and IGF-II on cancer cells are mediated through the IGF-IR, which is a tyrosine kinase and cancer cells with a strong tendency to metastasise have a higher expression of the IGF-IR. Most of the IGFs in circulation are bound to the IGFBPs, which regulate the bioavailability of the IGFs. All IGFBPs inhibit IGF action by high affinity binding, while some of them also potentiate the effects of IGFs. Colon cancer cells produce specific proteases that degrade the IGFBP so that the IGF will be free to act on the cancer cell in an autocrine manner. Therefore, the IGFBPs play a crucial role in the development of the cancer.

CONCLUSION

The current knowledge about the link between IGFs and colon cancer is mainly based on in vitro investigations. Further in vivo study is needed to understand the exact role of the IGF system, especially its binding proteins, so that they can be manipulated for the prevention and treatment of colorectal cancer.

Aging-associated changes in gene expression in the ACI rat prostate: Implications for carcinogenesis

BACKGROUND

Prostate cancer is the most frequently diagnosed neoplasm and the second leading cause of cancer-related mortality in men. Although the incidence of prostate cancer increases with age, the link between aging and prostate cancer is poorly understood.

METHODS

Affymetrix oligonucleotide microarrays were used to analyze the mRNA expression levels in the dorsolateral prostates from 6- and 18-month-old ACI rats. Real-time RT-PCR and immunohistochemistry was performed to validate microarray data in a select set of genes.

RESULTS

Microarray analysis revealed changes in gene expression associated with inflammation, oxidative stress, tissue remodeling, and energy metabolism. Most of these changes have been related to increased proliferative status of the prostate, anti-apoptosis, activated stroma, and alteration of the energy metabolism.

CONCLUSIONS

Age-associated alterations in the gene expression profile may put the aging prostate in risk for the initiation, promotion, and progression of neoplastic transformation in both our animal model and humans.

An ecologic study of dietary and solar ultraviolet-B links to breast carcinoma mortality rates

BACKGROUND

The role of diet in the etiology of breast carcinoma has been debated for decades. The ecologic approach generally finds that dietary fat is highly associated with breast carcinoma mortality, with fish intake and solar ultraviolet-B (UV-B) radiation, a source of vitamin D, inversely associated. Case-control and cohort studies generally find a variety of chemical, nonfat dietary, environmental, genetic, lifestyle, and reproductive factors to be important.

METHODS

An ecologic study was conducted using breast carcinoma mortality rates (1989-1996), dietary supply data, and latitude (an index of solar UV-B radiation) from 35 countries.

RESULTS

The fraction of energy derived from animal products (risk) combined with that from vegetable products (risk reduction), followed by solar UV-B radiation and, to a lesser extent, energy derived from alcohol (risk) and fish intake (risk reduction), were found to explain 80% of the variance of breast carcinoma mortality rates. Dietary fat contributed insignificantly in regressions involving the other factors.

CONCLUSIONS

It is hypothesized that animal products are associated with risk for breast carcinoma because they are associated with greater amounts of insulin-like growth factor-1 and lifetime doses of estrogen. Vegetable products contain several risk reduction components including antioxidants and phytoestrogens. The association with latitude is very likely because of solar UV-B radiation and vitamin D. Alcohol modulates estrogen's effects on breasts. Fish intake is associated with risk reduction through vitamin D and n-3 oils. These results are consistent with those of many case-control and cohort studies but should be assessed in well designed cohort studies.

Effects of aging on expression of genes involved in regulation of proliferation and apoptosis in the colonic epithelium

The purpose of this study was to characterize the effects of aging on colonic messenger ribonucleic acid (mRNA) and protein levels of genes involved in the regulation of cell proliferation and apoptosis, and epithelial morphology in male Fischer 344 rats. Our study shows that, with aging, colonic expression of insulin-like growth factor-1 (IGF-1) and IGF-binding protein-3 (IGFBP-3) is significantly increased and decreased, respectively. Colonic Bax protein levels are increased significantly with aging. Immunohistochemical localization of Bax protein shows a greatly increased expression in colonic crypts, especially in the upper portion of crypts. p53 expression is unchanged with aging. No significant change in proliferation of colonic crypt cells is observed by bromodeoxyuridine (BrdU) labeling, although the increased colonic expression of IGF-1 and the decreased expression of IGFBP-3 with aging may result in an increased colonic IGF-1 bioactivity. The age-related changes in Bax and IGFBP-3 appear to be independent of p53. The finding of an unchanged colonic epithelium with aging in the face of a greatly increased Bax protein levels may suggest that the elevated Bax protein levels function to render colonic epithelial cells more sensitive to apoptotic stimuli.