Ujjawal Sharma

Alkaline Phosphatase: An Overview

Alkaline phosphatase (ALP; E.C.3.I.3.1.) is an ubiquitous membrane-bound glycoprotein that catalyzes the hydrolysis of phosphate monoesters at basic pH values. Alkaline phosphatase is divided into four isozymes depending upon the site of tissue expression that are Intestinal ALP, Placental ALP, Germ cell ALP and tissue nonspecific alkaline phosphatase or liver/bone/kidney (L/B/K) ALP. The intestinal and placental ALP loci are located near the end of long arm of chromosome 2 and L/B/K ALP is located near the end of the short arm of chromosome 1. Although ALPs are present in many mammalian tissues and have been studied for the last several years still little is known about them. The bone isoenzyme may be involved in mammalian bone calcification and the intestinal isoenzyme is thought to play a role in the transport of phosphate into epithelial cells of the intestine. In this review, we tried to provide an overview about the various forms, structure and functions of alkaline phosphatase with special focus on liver/bone/kidney alkaline phosphatase.

Heterogenous spectrum of CFTR gene mutations in Indian patients with congenital absence of vas deferens

BACKGROUND Mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene can cause congenital bilateral absence of vas deferens. Yet, the spectrum and frequency of CFTR mutations in Indian males with congenital absence of vas deferens (CAVD) is unknown. METHODS We investigated 50 Indian males, diagnosed with unilateral or bilateral absence of vas deferens at the PGIMER, Chandigarh, for the presence of the most common CFTR gene mutations as well as unknown mutations by single-strand conformation polymorphism followed by sequence analysis. RESULTS This study led to the identification of 12 CFTR gene mutations on 48% of 100 Indian CAVD chromosomes. CFTR mutations were identified on both alleles in 11 patients (22%) and on one allele in 26 patients (52%). Novel CFTR mutations identified were L69H, F87I, G126S, F157C, E543A, Y852F and D1270E. The T5 allele (25%) and F508del (11%) were the most common mutations identified. The most common intragenic marker haplotype for F508del was 2111 (GATT, TUB9, M470V and T854T). No mutations could be detected in 13 CAVD patients (26%), including 4 with renal malformations. CONCLUSIONS This study confirms the molecular heterogeneity of CFTR mutations in CAVD. Although the mutation detection rate is indeed lower in Indian CAVD patients, 74% of the patients tested had at least one CFTR mutation. CAVD alleles with no mutations suggest that other changes may be located at the non-screened sites that require extensive search by direct sequencing. Furthermore, the novel CFTR mutations identified require functional studies in a cell-based system.

Over-Expression of Telomere Binding Factors (TRF1 & TRF2) in Renal Cell Carcinoma and Their Inhibition by Using SiRNA Induce Apoptosis, Reduce Cell Proliferation and Migration Invitro

Telomere binding factors viz. TRF1 and TRF2 are a part of sheltrin complex that are present exclusively at the ends of chromosomes. These factors play an important role in maintaining chromosomal integrity at the ends. However, their status and role are not clear in renal cell carcinoma (RCC). Therefore, the present study was conducted to evaluate TRF1 and TRF2 expressions in RCC tissues. Further, the role of these factors involved in tumorigenesis was elucidated by gene silencing using siRNA in RCC cell line (A498). The present study documented a significant over-expression of TRF1 (P = 0.005) and TRF2 (P = 0.0048) mRNAs by real time PCR in RCC tissues as compared with adjacent normal kidney tissues. Immunohistochemistry studies also revealed higher expression of TRF1 and TRF2 proteins in RCC. Moreover, TRF1 or TRF2 gene silencing using siRNA showed marked reduction in proliferation of RCC cells (P = 0.000). Further, significantly induced cell cycle arrest (P = 0.000) and apoptosis of RCC cells (P = 0.000) was documented upon TRF1 or TRF2 gene silencing. Henceforth, the results deduce that TRF1 or TRF2 inhibitions play an important role in the induction of apoptosis in A498 cells, which may serve as a potential therapeutic target in RCC.

Implication of BBM lipid composition and fluidity in mitigated alkaline phosphatase activity in renal cell carcinoma

Previous study has documented reduced alkaline phosphatase (ALP) activity in brush border membrane (BBM) isolated from renal cell carcinoma (RCC). Diminished activity of ALP is associated with alteration in both increased Km as well as decreased Vmax of enzyme suggests that there may be a change in the conformation of enzyme as well as decreased number of ALP active molecules. The present study was conducted to find out any role of BBM lipid composition and its fluidity in diminished activity of alkaline phosphatase in renal cell carcinoma. Total phospholipids and glycolipids were significantly augmented in BBM from RCC as compared to control. Fractional analysis of total phospholipids revealed significantly increased phosphatidylethanolamine. Decreased fractions of sphingomyelin and phosphatidylinositol were observed. Cholesterol-to-total phospholipid molar ratios in tumor BBM was a significantly lower in tumor BBM. A significant reduction in polarization and microviscosity was found in BBM from RCC. Therefore, we conclude that alteration in membrane lipid composition and fluidity may play a substantial role in reduced activity of ALP in RCC.

Association between ZIP10 gene expression and tumor aggressiveness in renal cell carcinoma

Zinc is an indispensable trace element which is vital for the functioning of numerous cellular processes like cell replication and growth. Cellular zinc homeostasis is tightly regulated by zinc transporters involved in zinc influx and efflux processes. Notwithstanding, the association of zinc transporters with the aggressiveness of cancer, especially renal cell carcinoma (RCC), is unknown. In view of the fact, the present study was initiated to ascertain whether ZIP10 transporter expression is modulated during RCC progression. A total of 57 samples of RCC and corresponding normal renal tissue were analyzed for ZIP10 gene expression by real time PCR. We observed significantly higher expression of ZIP10 mRNA (P=0.002) in high grade clear cell RCC tissue (Grades III & IV) as compared to low grade clear cell RCC tissue (Grades I & II). A significant difference was also observed in the ZIP10 expression in different types of RCC (P=0.001). This is the first study which shows a significant correlation between ZIP10 mRNA expressions with aggressiveness of RCC. Therefore, ZIP10 mRNA expression could be used as a possible biomarker for the aggressive behavior of RCC and a promising target of novel treatment strategies.

Augmented telomerase activity, reduced telomere length and the presence of alternative lengthening of telomere in renal cell carcinoma: plausible predictive and diagnostic markers.

In this study, we analyzed 100 cases of renal cell carcinoma (RCC) for telomerase activity, telomere length and alternative lengthening of telomeres (ALT) using the TRAP assay, TeloTTAGGG assay kit and immunohistochemical analysis of ALT associated promyelocytic leukemia (PML) bodies respectively. A significantly higher (P=0.000) telomerase activity was observed in 81 cases of RCC which was correlated with clinicopathological features of tumor for instance, stage (P=0.008) and grades (P=0.000) but not with the subtypes of RCC (P = 0.355). Notwithstanding, no correlation was found between telomerase activity and subtypes of RCC. Strikingly, the telomere length was found to be significantly shorter in RCC (P=0.000) to that of corresponding normal renal tissues and it is well correlated with grades (P=0.016) but not with stages (P=0.202) and subtypes (P=0.669) of RCC. In this study, telomere length was also negatively correlated with the age of patients (r(2)=0.528; P=0.000) which supports the notion that it could be used as a marker for biological aging. ALT associated PML bodies containing PML protein was found in telomerase negative cases of RCC. It suggests the presence of an ALT pathway mechanism to maintain the telomere length in telomerase negative RCC tissues which was associated with high stages of RCC, suggesting a prevalent mechanism for telomere maintenance in high stages. In conclusion, the telomerase activity and telomere length can be used as a diagnostic as well as a predictive marker in RCC. The prevalence of ALT mechanism in high stages of RCC is warranted for the development of anti-ALT inhibitors along with telomerase inhibitor against RCC as a therapeutic approach.

Hydronephrosis due to pelviureteric junction narrowing: Utility of urinary enzymes to predict the need for surgical management and follow-up

Aim: To study the role of urinary enzymes N-acetyl-β-glucosaminidase (NAG), alkaline phosphatase (AKP) and gamma glutamyl transferase (GGT) in the diagnosis and follow-up of patients with suspected pelviureteric junction obstruction (PUJO). Materials and Methods: A total of 70 patients, 29 managed conservatively (group A) and 41 managed by pyeloplasty (group B), were studied prospectively. A serial measurement of urinary enzymes NAG, AKP and GGT level was performed in both the groups. The mean levels of these urinary enzymes were compared between the two groups and among the patients of the same group at presentation as well as during follow-up. Results: There was a significant fall in the mean AKP level in patients managed conservatively at 8 months of follow-up. Similarly, in the operated group, there was a significant fall in the AKP levels at both 3 months and 8 months of follow-up. The mean level of GGT also showed a significant fall after 3 months of surgery but did not show further significant change at 8 months after surgery. The mean levels of NAG and GGT in the conservatively managed group were significantly low compared with that of patients requiring pyeloplasty at presentation as well as in the follow-up. The mean level of AKP was significantly low in the conservatively managed group when compared with the patients requiring surgery, but did not differ significantly in both the follow-ups after surgery. Conclusions: The level of urinary enzymes NAG, AKP and GGT are significantly high in the patients with hydronephrosis (HDN) requiring pyeloplasty when compared with the patients managed conservatively. The level of AKP significantly falls after pyeloplasty in the patients of HDN due to PUJO. There is a negative correlation with the preoperative level of enzyme NAG with split renal function in the patients of HDN requiring pyeloplasty.

Inverse correlation of intracellular calcium and cyclic AMP levels in renal cell carcinoma

Renal cell carcinoma (RCC) is the most common renal tumour in adults. Altered levels of secondary messengers, that is, intracellular calcium and cyclic AMP (cAMP), have been implicated in the pathogenesis of various malignancies. In the present study, we measured levels of intracellular calcium and cAMP in RCC. The intracellular calcium level was significantly reduced, whereas the cAMP level was significantly augmented in RCC as compared with adjacent grossly normal renal parenchyma. Copyright

Inhibition of hTERT expression by MAP kinase inhibitor induces cell death in renal cell carcinoma

BACKGROUND Human telomerase reverse transcriptase (hTERT) is one of the components of telomerase enzyme and its activity is associated with cell proliferation and differentiation. Extracellular signal regulated kinase (ERK)-mitogen activated protein kinase signaling pathway play an important role in hTERT expression. The present study was conducted to ascertain hTERT messenger RNA (mRNA) expression in renal cell carcinoma (RCC) and its association with clinicopathological characteristics. Further, we also explored hTERT targeting as possible tumor therapeutic. METHODS A total of 96 histopathologically confirmed RCC cases and corresponding normal tissues were subjected to hTERT gene expression using real-time PCR. Two RCC cell lines viz. ACHN and A498 were treated with MEK inhibitor (U0126) and hTERT mRNA expression, telomerase activity, cell viability, migration, and apoptosis were evaluated. RESULTS The hTERT mRNA levels were found to be significantly higher in RCC as compared with corresponding normal renal tissues (P = 0.040) as well as in high grades to that of low grades clear cell RCC (P = 0.008). Significantly diminished ERK phosphorylation and hTERT mRNA expression concomitantly reduced telomerase activity that was observed after U0126 treatment. Subsequently, cell viability and migration were significantly inhibited after treatment with U0126 in both the cell lines to that of control (P = 0.001). In addition, U0126-treated cells showed significantly increased apoptosis (P = 0.001) to that of controls. CONCLUSION Henceforth, this study infer that, hTERT expression can be used as a possible diagnostic marker for RCC, and inhibition of hTERT expression by hampering ERK-mitogen activated protein kinase cascade may be used as a promising anticancer target in RCC.

Therapeutic Anticancer Approaches Targeting Telomerase and Telomeres

Telomeres and telomerase are attractive targets for anticancer therapy. This is evidenced with the facts that majority of human cancers express the enzyme telomerase which is utmost important to maintain the telomere length, thereby to ensure indefinite cell proliferation – a hallmark of cancer. In human cells, a structure referred to as telomere has been identified to cap the terminal regions of chromosomes which can protect the ends of DNA strands from degradation and fusion, whereas telomerase plays a pivotal role in cellular immortality and tumorigenesis. Henceforth, strategies have been made to induce telomerase inhibition target virtually all of the major components of ribonucleoprotein holoenzyme and related cell signal pathways that regulates its activity which includes telomerase reverse transcriptase (hTERT) catalytic subunit, the telomere RNA component (hTERC), and associated proteins. It is noteworthy here that most of the cancers have an alternative lengthening of telomere termed as ALT even in the absence of telomerase activity. In these cases, there is an urgent need to understand the cell signaling pathways for ALT mechanism which can be used as therapeutic targets. Other strategies have been developed to target the protein associated with telomerase at the telomeric ends of chromosomes such as tankyrase. Increasing evidences suggest that directly targeting telomeric DNA using agents directed against the shelterin complex may also have anticancer activity. The limitations of strategies remain to be resolved to facilitate the clinical applications. In this chapter, recent development of strategies against these targets shall be discussed.