Shubham Pandey

Identification of a novel AMPK-PEA15 axis in the anoikis-resistant growth of mammary cells

IntroductionMatrix detachment triggers anoikis, a form of apoptosis, in most normal epithelial cells, while acquisition of anoikis resistance is a prime requisite for solid tumor growth. Of note, recent studies have revealed that a small population of normal human mammary epithelial cells (HMECs) survive in suspension and generate multicellular spheroids termed ‘mammospheres’. Therefore, understanding how normal HMECs overcome anoikis may provide insights into breast cancer initiation and progression.MethodsPrimary breast tissue-derived normal HMECs were grown as adherent monolayers or mammospheres. The status of AMP-activated protein kinase (AMPK) and PEA15 signaling was investigated by immunoblotting. Pharmacological agents and an RNA interference (RNAi) approach were employed to gauge their roles in mammosphere formation. Immunoprecipitation and in vitro kinase assays were undertaken to evaluate interactions between AMPK and PEA15. In vitro sphere formation and tumor xenograft assays were performed to understand their roles in tumorigenicity.ResultsIn this study, we show that mammosphere formation by normal HMECs is accompanied with an increase in AMPK activity. Inhibition or knockdown of AMPK impaired mammosphere formation. Concomitant with AMPK activation, we detected increased Ser116 phosphorylation of PEA15, which promotes its anti-apoptotic functions. Inhibition or knockdown of AMPK impaired PEA15 Ser116 phosphorylation and increased apoptosis. Knockdown of PEA15, or overexpression of the nonphosphorylatable S116A mutant of PEA15, also abrogated mammosphere formation. We further demonstrate that AMPK directly interacts with and phosphorylates PEA15 at Ser116 residue, thus identifying PEA15 as a novel AMPK substrate. Together, these data revealed that AMPK activation facilitates mammosphere formation by inhibition of apoptosis, at least in part, through Ser116 phosphorylation of PEA15. Since anoikis resistance plays a critical role in solid tumor growth, we investigated the relevance of these findings in the context of breast cancer. Significantly, we show that the AMPK-PEA15 axis plays an important role in the anchorage-independent growth of breast cancer cells both in vitro and in vivo.ConclusionsOur study identifies a novel AMPK-PEA15 signaling axis in the anchorage-independent growth of both normal and cancerous mammary epithelial cells, suggesting that breast cancer cells may employ mechanisms of anoikis resistance already inherent within a subset of normal HMECs. Thus, targeting the AMPK-PEA15 axis might prevent breast cancer dissemination and metastasis.

Assessment of Genetic Parameters for Various Productive Traits in Early Maturing Sugarcane

The cultivated varieties of sugarcane are interspecific hybrids involving at least three species, S. officinarum, S. barberi and S. spontaneum which themselves represent complex polyploidy. The chromosome number among varieties varies from 2n = 100 to 120. It is for this reason the sugarcane varieties are botanically described as Saccharum spp. complex hybrid. The heterozygous and polyploid nature of this crop has resulted in generation of greater genetic variability. The extent of genetic variability present in any crop is of paramount importance for its improvement. The information on the nature and the magnitude of variability present in the genetic material is of prime importance for a breeder to initiate any effective selection program. Genotypic and phenotypic coefficients of variation along with heritability as well as genetic advance are very essential to improve productive trait of sugarcane because this would help in knowing whether or not the desired objective can be achieved from the material (Tyagi and Singh, 1998). So, present study was under taken to assess the extent of genetic variability, heritability, genetic advance of some important traits of early maturing sugarcane International Journal of Current Microbiology and Applied Sciences ISSN: 2319-7706 Volume 7 Number 05 (2018) Journal homepage: http://www.ijcmas.com