Olaparib modulates DNA repair efficiency, sensitizes cervical cancer cells to cisplatin and exhibits anti-metastatic property

Abstract PARP1 trapping at DNA lesion by pharmacological inhibitors has been exploited in several cancers exhibiting defects in DNA repair mechanisms. PARP1 hyperactivation is involved in therapeutic resistance in multiple cancers. The role of PARP1 in cervical cancer (CC) resistance and implication of PARP inhibitor is yet to be elucidated. Our data demonstrates significantly higher expression of PARP1 in primary cervical tumors and CC cell lines SiHa and ME180. Upon cisplatin treatment CC cells display significant overexpression of PARP1 and its hyperactivation. PARP inhibitor olaparib shows significant anti-proliferative effect on CC cells and drive loss of clonogenic survival and enhanced cell death in combination with cisplatin. PARP inhibited cells show delay in resolution of γH2A.X foci and prolonged late S and G2-M phase arrest resulting in apoptosis. Further, PARP inhibition disrupts the localization of base excision repair (BER) effector XRCC1 and non-homologous end joining (NHEJ) proteins Ku80 and XRCC4. Due to disrupted relocation of repair factors, cisplatin induced stalled replication forks collapse and convert into double strand breaks (DSBs). Interestingly, PARP inhibition also shows anti-migratory and anti-invasive properties in CC cells, increases anchorage independent cell death and induces anoikis. Collectively, our data demonstrates therapeutic potential of PARP inhibitor in cervical cancer

Epigenetic Silencing of CXCR4 Promotes Loss of Cell Adhesion in Cervical Cancer

In the network of chemokine signaling pathways, recent reports have described the SDF-1α/CXCR4 axis and its role in cancer progression and metastasis. Interestingly, we found downregulation of CXCR4 at both transcript and protein level in cervical cancer cell lines and primary tumors. We also found CXCR4 promoter hypermethylation in cervical cancer cell lines and primary biopsy samples. DNA hypomethylating drug 5-AZA-2′-deoxycytidine and histone deacetylase inhibitor Trichostatin A treatments in cell lines reactivate both CXCR4 transcription and protein expression. Cell adhesion assay demonstrated that autocrine SDF-1α promotes the loss of cell adhesion while paracrine SDF-1α predominantly protects the normal cervical cells from loss of cell adhesion. Cervical cancer cell line C-33A having increased expression of CXCR4 after TSA treatment showed increased cell adhesion by paracrine source of SDF-1α in comparison to untreated C-33A. These findings demonstrate the first evidence that epigenetic silencing of CXCR4 makes the cells inefficient to respond to the paracrine source of SDF-1α leading to loss of cell adhesion, one of the key events in metastases and progression of the disease. Our results provide novel insight of SDF-1α/CXCR4 signaling in tumor microenvironment which may be promising to further delineate molecular mechanism of cervical carcinogenesis

Complex consequences of conservation success: Emerging human-tiger conflicts in Nepal

Between 1910 and 2010, range-wide tiger populations plummeted from around 100,000 to an estimated 3,200. Poaching, habitat destruction and human-wildlife conflict have all contributed to this dramatic decrease. In Nepal, the Bardia-Banke Complex, consisting of Bardia National Park (BNP) and Banke National Park (BaNP) and their buffer-zones, is a critical habitat to the Bengal tiger Panthera tigris. Conservation efforts in recent decades have contributed to increasing the tiger population. Despite this increase, no human fatalities associated with human-tiger conflict were reported in the decade prior to 2019: a crucial feature of conservation success. In 2019, ten reported human-tiger incidents resulted in seven human fatalities, three people badly injured, and one tiger taken into captivity. The question of why conflicts involving humans and tigers have suddenly increased requires urgent answers to inform future policy. The development and implementation of case-specific coexistence strategies is a prerequisite to the conservation of this iconic species. This paper explores the complex unintended consequences of conservation success and critically evaluates the circumstances that may explain this recent surge in human deaths and injuries

Over expression of minichromosome maintenance genes is clinically correlated to cervical carcinogenesis.

Minichromosome Maintenance (MCM) proteins play important roles in cell cycle progression by mediating DNA replication initiation and elongation. Among 10 MCM homologues MCM 2-7 form a hexamer and assemble to the pre-replication complex acting as replication licensing factors. Binding and function of MCM2-7 to pre-replication complex is regulated by MCM10 mediated binding of RECQL4 with MCM2-7. The purpose of this study is to explore the role of MCMs in cervical cancer and their correlation with the clinical parameters of cervical cancer. We have investigated sixty primary cervical cancer tissue samples, eight cervical cancer cell lines and thirty hysterectomised normal cervical tissue. The expression profiling of MCMs was done using semi-quantitative RT-PCR, immunoblotting and immunohistochemistry. MCM2, 4, 5, 6, 7, 10 and RECQL4 are significantly over-expressed in cervical cancer. Among these, MCM4, 6 and 10 show increased frequency of over expression along with advancement of tumor stages. MCM4, 5 and 6 also show differential expression in different types of lesion, while MCM2 and MCM10 are over expressed in cervical cancer irrespective of clinico-pathological parameters. Our data indicates the role of MCM4, MCM5, MCM6, MCM10 and RECQL4 in the progression of cervical cancer

Cyclin D1 and cyclin E2 are differentially expressed in gastric cancer

Cell cycle regulators cyclin D1 and cyclin E2 function in G1/S transition by activating downstream cyclin-dependent kinases. Deregulated expression of these cyclins has been reported in various cancers. However, little is known about their clinical significance in gastric carcinoma. We aimed to explore that whether there is differential expression of these cyclins in clinically distinct gastric cancer patients. In this study we recruited a total of 92 subjects including 20 controls and 72 cases of histopathologically proven gastric carcinoma. Expression profiling at transcript level was done by semiquantitative RT-PCR and of protein by immunohistochemistry. Receiver operator characteristics analysis was done for determining diagnostic utility of cyclin D1 and cyclin E2. We demonstrate that cyclins D1 and E2 are frequently overexpressed in early stages of gastric carcinoma. Interestingly, expression of cyclins D1 and E2 significantly correlates with different clinical parameters such as gender, histological type (intestinal and diffuse), tumor location (proximal, middle, and distal), tumor differentiation (differentiated and undifferentiated), tumor invasion (serosal, lymphatic, and venous) and tumor metastasis (lymph node, peritoneal, ascites, and liver). Cyclin D1 has significantly higher sensitivity and specificity as diagnostic biomarker than cyclin E2. Our results suggest that overexpression of cyclin D1 and cyclin E2 is an early event in gastric carcinogenesis. The differential expression of these cyclins may be useful as diagnostic biomarkers for early detection of gastric carcinoma

cDNA cloning and characterization of a ribosome inactivating protein of a hemi-parasitic plant (Viscum album L.) from North-Western Himalaya (India)

Mistletoe ribosome inactivating proteins (RIPs) are excellent immunomodulators obtained from a hemi-parasitic plant Viscum album L. In the present study, we have characterized and cloned a 65 kDa heterodimeric RIP from Himalayan V. album. Himalayan mistletoe ribosome inactivating protein (HmRIP) possessed unique sugar affinity for l-Rhamnose, Meso-inositol and l-Arabinose besides Galactose and N-acetyl-Galactosamine. The lectin activity was stable to a broad range of temperature (4-65°C) and pH (2.5-12.5). cDNA cloning showed that HmRIP is 500 amino acids long and shortest among mistletoe RIPs. Amino acid sequence analyses revealed important differences at the functionally significant sites. In the lectin subunit, two critical residues forming base of the 2γ sugar-binding cleft were deleted. Such differences lead to a different conformation of sugar-binding cleft giving rise to unique sugar-binding properties of HmRIP. Toxin subunit also showed a sizeable deletion of four residue segment in the antigenic epitope (83-103) determining its antigenecity. Due to striking differences at the functional sites associated with medicinal properties, HmRIP is a novel type II RIP. In the phylogenetic tree based on amino acid sequence of type II RIPs from six dicot families, mistletoe RIPs branched out from the RIPs of all other taxa and formed a distinct and distant group supporting independent evolution of Viscaceae among the angiosperms

Bioinsecticidal activity of Archidendron ellipticum trypsin inhibitor on growth and serine digestive enzymes during larval development of Spodoptera litura

The roles of serine proteases involved in the digestion mechanism of the cutworm Spodoptera litura (Lepidoptera: Noctuidae) were examined (in vitro and in vivo) following feeding of plant protease inhibitors. A trypsin inhibitor from Archidendron ellipticum (AeTI) was purified by ammonium sulfate fractionation, ion-exchange chromatography and size-exclusion chromatography (HPLC) and its bioinsecticidal properties against S. litura were compared with Soybean Kunitz trypsin inhibitor (SBTI). AeTI inhibited the trypsin-like activities of the midgut proteases of fifth instar larvae of S. litura by over 70%. Dixon plot analysis revealed competitive inhibition of larval midgut trypsin and chymotrypsin by AeTI, with an inhibition constant (Ki) of 3.5 × 10-9 M and 1.5 × 10-9 M, respectively. However, inhibitor kinetics using double reciprocal plots for both trypsin and chymotrypsin inhibitions demonstrated a mixed inhibition pattern. Feeding experiments conducted on different (neonate to ultimate) instars suggested a dose-dependent decrease for both the larval body weight as well as % survival of larva fed on diet containing 50, 100 and 150 μM AeTI. Influence of AeTI on the larval gut physiology indicated a 7-fold decrease of trypsin-like protease activity and a 5-fold increase of chymotrypsin-like protease activity, after being fed with a diet supplemented with 150 μM AeTI. This study suggests that although the early (1st to 3rd) larval instars of S. litura are susceptible to the trypsin inhibitory action of AeTI, the later instars may facilitate the development of new serine proteases, insensitive to the inhibitor

Human papillomavirus genotype distribution in cervical cancer biopsies from Nepalese women

Abstract Background Cervical cancer (CC) is the leading cause of morbidity and mortality from cancer in Nepalese women. Nearly all cases of CC are caused by infection with certain genotypes of human papillomavirus (HPV). Data on HPV genotype distribution in Nepalese CC patients is sparse. We aimed to determine the distribution of HPV genotypes in biopsies of CC tissue from Nepalese women. Methods This study examined 248 archived paraffin-embedded tissue specimens from CC cases from patients of B.P. Koirala Memorial Cancer Hospital, Bharatpur, Chitwan, Nepal. DNA was extracted from the biopsies and HPV detection performed by PCR. HPV genotyping was then carried out by a reverse line hybridization technique capable of identifying 36 distinct HPV genotypes. Results Most of the samples were from tumors that had been designated by hospital pathologists as squamous cell carcinoma (77.6%). 165 of the 248 samples contained DNA of sufficient quality for rigorous PCR testing. All the analyzable specimens were positive for HPV. The most common HPV genotypes, in decreasing order of frequency were 16, 18, 45, 33, 52, 56 and 31; most were found as single infections (94.5%). Together, HPV types 16, 18, and 45 were found in 92% of the tumor samples. Conclusion This study strengthens the knowledge-base of HPV genotype distribution in CC cases in Nepal. Hopefully, this information will be useful to the medical community and public health policy-makers in generating improved HPV-surveillance, −prevention and -treatment strategies in Nepal

Crystal structure of Himalayan mistletoe ribosome-inactivating protein reveals the presence of a natural inhibitor and a new functionally active sugar-binding site

Ribosome-inactivating proteins (RIPs) are toxins involved in plant defense. How the plant prevents autotoxicity is not yet fully understood. The present study is the first structural evidence of a naturally inhibited form of RIP from a plant. Himalayan mistletoe RIP (HmRIP) was purified from Viscum album leaves and crystallized with lactose. The structure was determined by the molecular replacement method and refined at 2.8-Å resolution. The crystal structure revealed the presence of high quality non-protein electron density at the active site, into which a pteridine derivative (2-amino 4-isopropyl 6-carboxyl pteridine) was modeled. The carboxyl group of the ligand binds strongly with the key active site residue Arg162, nullifies the positive charge required for catalysis, and thereby acts as a natural inhibitor. Lectin subunits of RIPs have two active sugar-binding sites present in 1α- and 2γ-subdomains. A third functionally active site has been identified in the 1β-subdomain of HmRIP. The 1β-site is active despite the absence of conserved polar sugar-binding residues. Loss of these residues is compensated by the following: (i) the presence of an extended site where the penultimate sugar also interacts with the protein; (ii) the interactions of galactose with the protein main chain carbonyl and amide nitrogen atoms; (iii) the presence of a well defined pocket encircled by four walls; and (iv) a favorable stacking of the galactose ring with Tyr66 besides the conserved Phe75. The mode of sugar binding is also distinct at the 1α and 2γ sugar-binding sites