The roles of sex steroid receptor coregulators in cancer

Sex steroid hormones, estrogen, progesterone and androgen, play pivotal roles in sex differentiation and development, and in reproductive functions and sexual behavior. Studies have shown that sex steroid hormones are the key regulators in the development and progression of endocrine-related cancers, especially the cancers of the reproductive tissues. The actions of estrogen, progesterone and androgen are mediated through their cognate intracellular receptor proteins, the estrogen receptors (ER), the progesterone receptors (PR) and the androgen receptor (AR), respectively. These receptors are members of the nuclear receptor (NR) superfamily, which function as transcription factors that regulate their target gene expression. Proper functioning of these steroid receptors maintains the normal responsiveness of the target tissues to the stimulations of the steroid hormones. This permits the normal development and function of reproductive tissues. It can be inferred that factors influencing the expression or function of steroid receptors will interfere with the normal development and function of the target tissues, and may induce pathological conditions, including cancers. In addition to the direct contact with the basal transcription machinery, nuclear receptors enhance or suppress transcription by recruiting an array of coactivators and corepressors, collectively named coregulators. Therefore, the mutation or aberrant expression of sex steroid receptor coregulators will affect the normal function of the sex steroid receptors and hence may participate in the development and progression of the cancers

Clinical implications of novel activating EGFR mutations in malignant peritoneal mesothelioma

<p>Abstract</p> <p>Background</p> <p>There is a paucity of information about the molecular perturbations involved in MPM tumor formation. We previously reported that EGFR-TK mutations in MPM were predictive of achieving optimal surgical cytoreduction, but the status of EGFR pathway activation potential of these mutations was not known. Here we present the mutant EGFR activating potential and the matured survival data of the EGFR mutant(mut+) relative to wild type EGFR(mut-) mesothelioma.</p> <p>Methods</p> <p>Twenty-nine patients were evaluated and their tumors were probed for mutations in the catalytic TK-domain. Twenty-five patients were treated with cytoreductive surgery and complete clinical data was available for comparison of the mut+ and mut- groups. A COS-7 cell expression model was used to determine mutation activating profiles and response to erlotinib.</p> <p>Results</p> <p>Functional mutations were found in 31%(9/29) of patients; 7 of these mutations were novel and another was the L858R mutation. All missense mutations were found to be activating mutations and responsive to erlotinib. Of the 25 patients managed surgically, there were 7 mut+ and 18 mut-. Two of 7 (29%) mut+ developed progressive disease and died with a median follow-up time of 22 months; while 13/18 (72%) mut- developed progressive disease and 10/18 (56%) died with median TTP of 12 months and median survival of 14 months.</p> <p>Conclusions</p> <p>The novel EGFR mutations identified are activating mutations responsive to erlotinib. The mut+ subset have a 'relative' improved outcome. Erlotinib may have a role in MPM and exploration for mutations in a larger patient cohort is warranted.</p

Low Grade Peritoneal Mucinous Carcinomatosis Associated with Human Papilloma Virus Infection: Case Report

Pseudomyxoma peritonei is a clinical syndrome characterized by peritoneal dissemination of a mucinous tumor with mucinous ascites. The vast majority of the pseudomyxoma peritoneis are associated with mucinous neoplasms of the appendix. We describe a case of pseudomyxoma peritonei associated with mucinous adenocarcinoma of the cervix in a 60-year-old woman. The patient developed low grade mucinous peritoneal carcinomatosis 8 years after hysterectomy for cervical adenocarcinoma. No other primary mucinous tumor was identified and peritoneal carcinomatosis tested positive for high-risk human papilloma virus (HPV), showing both integrated and episomal pattern. HPV has been previously associated with development of cervical carcinomas (both squamous and mucinous) but neither has cervical adenocarcinoma nor HPV been implicated in development of pseudomyxoma peritonei. To the best of our knowledge, this is the first description of HPV-associated malignancy presenting as pseudomyxoma peritonei

Bilateral blockade of MEK- and PI3K-mediated pathways downstream of mutant KRAS as a treatment approach for peritoneal mucinous malignancies - Fig 4

<p><b>A.</b> Resistance to PI3Ki is correlated to increased pERK. Western blots of proteins isolated from LS174T cells treated with either MEKi, PI3Ki or both were probed with anti-phosphoERK1/2 (pERK1/2), anti-total ERK1/2, anti-phosphoAKT (pAKT) or anti-total AKT. Elevated levels of pERK1/2 (A, green arrow) and pAKT (A, green arrow) were seen 72 hours after exposure to PI3Ki coincident with the development of resistance to this inhibitor. <b>B.</b> Increased receptor tyrosine kinase (RTK) phosphorylation upon prolonged exposure to PI3K inhibitors. Protein lysates from PI3Ki-treated LS174T or RW7213 cells (72 hours) were incubated with human phospho-RTK array containing 49 RTKs, washed and probed with anti-phospho-tyrosine antibodies. Antigen-antibody complexes were detected by chemiluminescence and the results were quantified by densitometry. Numbers within brackets indicate fold increase in RTKs in PI3Ki-treated MCA cells relative to vehicle-treated controls. <b>C.</b> Synergistic reduction in viability of MCA cells treated with PI3K inhibitor and Linsitinib (inhibitor of IR and IGFR1). LS174T and RW7213 cells were treated with Linsitinib (blue) and PI3Ki (red) as single agents or in combination (green) in a fixed ratio for 72 hours. Each data point is the average of an n = 6. Error bars indicate standard error of the mean.</p

MCA cells are sensitive to MEK inhibition in vitro.

<p><b>A.</b> LS174T, RW7213 and RW2982 cells were treated with increasing concentrations of the MEK inhibitor, Cobimetinib, for 96 hours. <b>B.</b> Mutant KRAS knockdown sensitizes MCA cells to MEK inhibition. LS174T and RW7213 cells, either untreated (blue) or induced with DOX (green) to knockdown mutant KRAS were treated with increasing concentrations of Cobimetinib (MEKi). The half-maximal concentration (IC50) of Cobimetinib was reduced from 0.28 μM to 0.042 μM (6.7 fold) in LS174T cells and from 0.24 μM to 0.022 μM (10.7 fold) in RW7213 cells. <b>C.</b> MEKi and PI3Ki combination treatment synergistically reduces viability of MCA in vitro. LS174T and RW7213 cells were treated with MEKi (blue) and PI3Ki (red) as single agents or in combination (green) in a fixed ratio for 72 hours. Each data point on all graphs is the average of an n = 6. Error bars indicate standard error of the mean.</p

Inducible and reversible knockdown of mutant and wildtype KRAS in vitro.

<p><b>A.</b> The pINDUCER lentiviral vector was used for targeted knockdown KRAS in MCA cells in vitro. Addition (+) or withdrawal (-) of DOX induced or extinguished respectively, the expression of KRAS shRNA (Fig adapted from Meerbrey et al. 2011). <b>B.</b> Western blots showing reduction of KRAS protein expression after induction of shRNA targeting wildtype and mutant KRAS in LS174T cells (red arrow) and restoration of KRAS protein expression within 2 days after DOX withdrawal (green arrow). Note that the KRAS western blot shown in panel B was probed with an anti-KRAS antibody that binds to both wildtype and mutant KRAS. <b>C-E.</b> KRAS knockdown reduces MUC2 protein expression in MCA in vitro. Knockdown of wildtype and mutant KRAS in LS174T (B) and RW7213 (D) cells reduces MUC2 protein expression (C, E). Note that the KRAS western blot shown in panel D was probed with an anti-KRAS antibody that binds to both wildtype and mutant KRAS. <b>F, G.</b> Knockdown of mutant but not wild type KRAS reduces MUC2. Western blots of mutant KRAS (F), wildtype KRAS (G) and MUC2 protein (F, G, bottom panels) expression in LS174T cells. Mutant KRAS knockdown in LS174T cells (F, top panel, arrows) substantially reduces MUC2 protein levels (F, bottom panel, arrows). In contrast, knockdown of wildtype KRAS (G, top panel, arrow) did not reduce MUC2 protein expression (G, bottom panel, arrow). Note that the KRAS western blot presented in panel F was probed with an anti-KRASG12D specific antibody that binds only to mutant KRAS protein while the western blot in panel G was probed with an antibody that binds both wildtype and mutant KRAS proteins. Knockdown of wildtype KRAS did not alter mutant KRAS protein levels (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0179510#pone.0179510.s003" target="_blank">S3 Fig</a>). <b>H, I.</b> HRAS and NRAS are dispensable for MUC2 expression. Quantitative RTPCR results show reduction of HRAS and NRAS in LS174T cells (H). Error bars indicate standard error of the mean. Knockdown of HRAS or NRAS did not reduce MUC2 protein expression (I, green arrows) in contrast to KRAS knockdown (I, red arrow). Expression levels of proteins on western blots were quantified by densitometry and percent protein (MUC2 or KRAS) expression in DOX-treated (+) samples relative to untreated (-) controls (normalized to actin) are shown below the blots. Abbreviations: d, days; 5d+/2d- indicates that cells were cultured for 5 days in the presence of DOX and for 2 days after the removal of DOX.</p