Oliver Jonas

Potential role of intratumor bacteria in mediating tumor resistance to the chemotherapeutic drug gemcitabine

In model systems, bacteria present in human pancreatic tumors confer resistance to the anticancer drug gemcitabine. Debugging a cancer therapy Microbes contribute not only to the development of human diseases but also to the response of diseases to treatment. Geller et al. show that certain bacteria express enzymes capable of metabolizing the cancer chemotherapeutic drug gemcitabine into an inactive form. When bacteria were introduced into tumors growing in mice, the tumors became resistant to gemcitabine, an effect that was reversed by antibiotic treatment. Interestingly, a high percentage of human pancreatic ductal adenocarcinomas, a tumor type commonly treated with gemcitabine, contain the culprit bacteria. These correlative results raise the tantalizing possibility that the efficacy of an existing therapy for this lethal cancer might be improved by cotreatment with antibiotics. Science, this issue p. 1156 Growing evidence suggests that microbes can influence the efficacy of cancer therapies. By studying colon cancer models, we found that bacteria can metabolize the chemotherapeutic drug gemcitabine (2′,2′-difluorodeoxycytidine) into its inactive form, 2′,2′-difluorodeoxyuridine. Metabolism was dependent on the expression of a long isoform of the bacterial enzyme cytidine deaminase (CDDL), seen primarily in Gammaproteobacteria. In a colon cancer mouse model, gemcitabine resistance was induced by intratumor Gammaproteobacteria, dependent on bacterial CDDL expression, and abrogated by cotreatment with the antibiotic ciprofloxacin. Gemcitabine is commonly used to treat pancreatic ductal adenocarcinoma (PDAC), and we hypothesized that intratumor bacteria might contribute to drug resistance of these tumors. Consistent with this possibility, we found that of the 113 human PDACs that were tested, 86 (76%) were positive for bacteria, mainly Gammaproteobacteria.

An implantable microdevice to perform high-throughput in vivo drug sensitivity testing in tumors

An implantable microdevice is demonstrated to release microdoses of multiple drugs into confined regions of tumors and allows for assessment of each drug’s efficacy to identify optimal therapy. Drug-releasing implant tests cancer’s resolve Predicting whether a patient will respond to a drug is not easy, often relying on empirical evidence. Toward personalized medicine, animal models of patient tumors have been developed as well as engineered cell-material combinations meant to replicate a tumor in vitro. But the true test of whether a tumor responds to a drug will be by evaluating the tumor itself, within its own microenvironment. To this end, Jonas et al. created miniature drug delivery vessels that can be implanted with a standard biopsy needle directly into the tumor. These vessels, less than 1 mm in diameter, contained up to 16 microwells that each released a bolus of drug into the surrounding tumor tissue. The device and its surrounding tissue were then removed with a larger coring needle to see if the cancer cells had responded to the drug—or combination of drugs. In mouse models of melanoma, breast, or prostate cancers, the local response to a common chemotherapeutic, doxorubicin, matched the tumor response to systemic therapy. Furthermore, in a mouse model of triple-negative breast cancer, tumor sensitivity to five different locally delivered cancer drugs was identical to tumor response after intravenous administration of drug; for instance, tumors were most responsive to paclitaxel and least responsive to lapatinib. Such tiny drug-releasing devices can be implanted at different locations within the tumor, overcoming issues with tumor heterogeneity, and allowing for reproducible evaluation of drug sensitivity directly within the patient. Current anticancer chemotherapy relies on a limited set of in vitro or indirect prognostic markers of tumor response to available drugs. A more accurate analysis of drug sensitivity would involve studying tumor response in vivo. To this end, we have developed an implantable device that can perform drug sensitivity testing of several anticancer agents simultaneously inside the living tumor. The device contained reservoirs that released microdoses of single agents or drug combinations into spatially distinct regions of the tumor. The local drug concentrations were chosen to be representative of concentrations achieved during systemic treatment. Local efficacy and drug concentration profiles were evaluated for each drug or drug combination on the device, and the local efficacy was confirmed to be a predictor of systemic efficacy in vivo for multiple drugs and tumor models. Currently, up to 16 individual drugs or combinations can be assessed independently, without systemic drug exposure, through minimally invasive biopsy of a small region of a single tumor. This assay takes into consideration physiologic effects that contribute to drug response by allowing drugs to interact with the living tumor in its native microenvironment. Because these effects are crucial to predicting drug response, we envision that these devices will help identify optimal drug therapy before systemic treatment is initiated and could improve drug response prediction beyond the biomarkers and in vitro and ex vivo studies used today. These devices may also be used in clinical drug development to safely gather efficacy data on new compounds before pharmacological optimization.

Direct evidence for cancer-cell-autonomous extracellular protein catabolism in pancreatic tumors

Mammalian tissues rely on a variety of nutrients to support their physiological functions. It is known that altered metabolism is involved in the pathogenesis of cancer, but which nutrients support the inappropriate growth of intact malignant tumors is incompletely understood. Amino acids are essential nutrients for many cancer cells that can be obtained through the scavenging and catabolism of extracellular protein via macropinocytosis. In particular, macropinocytosis can be a nutrient source for pancreatic cancer cells, but it is not fully understood how the tumor environment influences metabolic phenotypes and whether macropinocytosis supports the maintenance of amino acid levels within pancreatic tumors. Here we utilize miniaturized plasma exchange to deliver labeled albumin to tissues in live mice, and we demonstrate that breakdown of albumin contributes to the supply of free amino acids in pancreatic tumors. We also deliver albumin directly into tumors using an implantable microdevice, which was adapted and modified from ref. 9. Following implantation, we directly observe protein catabolism and macropinocytosis in situ by pancreatic cancer cells, but not by adjacent, non-cancerous pancreatic tissue. In addition, we find that intratumoral inhibition of macropinocytosis decreases amino acid levels. Taken together, these data suggest that pancreatic cancer cells consume extracellular protein, including albumin, and that this consumption serves as an important source of amino acids for pancreatic cancer cells in vivo.

Tumor Cell–Driven Extracellular Matrix Remodeling Drives Haptotaxis during Metastatic Progression

UNLABELLED Fibronectin (FN) is a major component of the tumor microenvironment, but its role in promoting metastasis is incompletely understood. Here, we show that FN gradients elicit directional movement of breast cancer cells, in vitro and in vivo Haptotaxis on FN gradients requires direct interaction between α5β1 integrin and MENA, an actin regulator, and involves increases in focal complex signaling and tumor cell-mediated extracellular matrix (ECM) remodeling. Compared with MENA, higher levels of the prometastatic MENA(INV) isoform associate with α5, which enables 3-D haptotaxis of tumor cells toward the high FN concentrations typically present in perivascular space and in the periphery of breast tumor tissue. MENA(INV) and FN levels were correlated in two breast cancer cohorts, and high levels of MENA(INV) were significantly associated with increased tumor recurrence as well as decreased patient survival. Our results identify a novel tumor cell-intrinsic mechanism that promotes metastasis through ECM remodeling and ECM-guided directional migration. SIGNIFICANCE Here, we provide new insight into how tumor cell:ECM interactions generate signals and structures that promote directed tumor cell migration, a critical component of metastasis. Our results identify a tumor cell-intrinsic mechanism driven by the actin regulatory protein MENA that promotes ECM remodeling and haptotaxis along FN gradients. Cancer Discov; 6(5); 516-31. ©2016 AACR.See related commentary by Santiago-Medina and Yang, p. 474This article is highlighted in the In This Issue feature, p. 461.

The association of low socio-economic status in metropolitan Adelaide with maternal demographic and obstetric characteristics and pregnancy outcome

The South Australian perinatal statistics collection for 1988 was used to consider the association of low socio-economic status in metropolitan Adelaide (South Australia) with maternal demographic and obstetric characteristics and pregnancy outcome in 12047 singleton births. Socio-economic status — low, middle or high — was inferred from the socio-economic rating of the postcode of residence.Chi-squared analyses were carried out to test for significant trends in proportions of pregnancy and pregnancy outome variables across the socio-economic groupings. There was trend for the proportions of adverse obstetric and perinatal outcomes to decrease with increasing level of socio-economic status.Logistic regression analysis, adjusted for maternal age, marital status, race, parity and gestational age, confirmed the findings of the trend analyses, namely that mothers from the poor socio-economic areas were at a greater risk for poor pregnancy outcome. These poor outcomes included Apgar scores of less that 7 at both 1 and 5 minutes after birth, delay in onset of regular breathing of 5 minutes or longer; the need for intubation; the use of narcotic antagonists; low birthweight of under 2500 g; the need for special nursey care; and neonatal death.

Force propagation and force generation in cells.

Determining how forces are produced by and propagated through the cytoskeleton (CSK) of the cell is of great interest as dynamic processes of the CSK are intimately correlated with many molecular signaling pathways. We are presenting a novel approach for integrating measurements on cell elasticity, transcellular force propagation, and cellular force generation to obtain a comprehensive description of dynamic and mechanical properties of the CSK under force loading. This approach uses a combination of scanning force microscopy (SFM) and Total Internal Reflection Fluorescence (TIRF) microscopy. We apply well‐defined loading schemes onto the apical cell membrane of fibroblasts using the SFM and simultaneously use TIRF microscopy to image the topography of the basal cell membrane. The locally distinct changes of shape and depth of the cytoskeletal imprints onto the basal membrane are interpreted as results of force propagation through the cytoplasm. This observation provides evidence for the tensegrity model and demonstrates the usefulness of our approach that does not depend on potentially disturbing marker compounds. We confirm that the actin network greatly determines cell stiffness and represents the substrate that mediates force transduction through the cytoplasm of the cell. The latter is an essential feature of tensegrity. Most importantly, our new finding that, both intact actin and microtubule networks are required for enabling the cell to produce work, can only be understood within the framework of the tensegrity model. We also provide, for the first time, a direct measurement of the cells mechanical power output under compression at two femtowatts.

Integrated genetic and pharmacologic interrogation of rare cancers

Identifying therapeutic targets in rare cancers remains challenging due to the paucity of established models to perform preclinical studies. As a proof-of-concept, we developed a patient-derived cancer cell line, CLF-PED-015-T, from a paediatric patient with a rare undifferentiated sarcoma. Here, we confirm that this cell line recapitulates the histology and harbours the majority of the somatic genetic alterations found in a metastatic lesion isolated at first relapse. We then perform pooled CRISPR-Cas9 and RNAi loss-of-function screens and a small-molecule screen focused on druggable cancer targets. Integrating these three complementary and orthogonal methods, we identify CDK4 and XPO1 as potential therapeutic targets in this cancer, which has no known alterations in these genes. These observations establish an approach that integrates new patient-derived models, functional genomics and chemical screens to facilitate the discovery of targets in rare cancers.

A South Australian study of pregnancy and birth risk factors associated with cerebral palsy

Using the Perinatal Statistics Collection compiled by the Pregnancy Outcome Unit of the South Australian Health Commission, a profile of statistically significant risk factors for cerebral palsy has been established for a South Australian population. Logistic regression analysis revealed that these factors included threatened miscarriage, ante-partum haemorrhage, maternal age of under 20 years, shortened gestational age, low birthweight, low Apgar score at 5 minutes, foetal distress, delay in establishing spontaneous regular respiration, presence of a congenital abnormality and prolonged hospital stay. In addition, pregnancy hypertension, reduced number of antenatal visits, breech presentation, resuscitation of the neonate by intubation and intermittent positive pressure ventilation, and the need for specialised nursery care were found to be significant in univariate analyses. These data point to the risk factors which may help identify infants who require closer monitoring for early signs of cerebral palsy.

Pregnancy and birth risk factors for intellectual disability in South Australia.

It is generally accepted that developmental handicaps can often be minimized through early detection and intervention. For this reason, it is normal practice in many hospitals to follow-up and screen infants who present at birth with established risk factors. Clinical judgement will always be important when selecting children for follow-up. However, as hospital data systems improve, automated systems could be developed for listing children potentially “at risk”. Where initial clinical decisions not to follow-up individual children prove to be at odds with this automated output, the individual child could be re-assessed clinically. This process could increase the level of quality control. An initial risk-factor model for intellectual disability has been developed, based on the South Australian Perinatal Statistics Collection, for use in this context.

Caesarean Section in South Australia, 1986

Summary: A profile of Caesarean section in South Australia was obtained by analysing the 19,800 births in the perinatal statistics collection in 1986. The Caesarean confinement rate was 19.0%, of which 9.0% were elective sections and 9.9% emergency sections. The rates were highest in large metropolitan hospitals. Elective rates were highest in metropolitan private hospitals, among older women, among those with a previous perinatal death or where a fetal malpresentation occurred. Emergency sections were more common in primigravidas, non‐Caucasian women, those with a poor pregnancy history, few antenatal visits and a medical or obstetric complication of pregnancy. The obstetric complications most commonly encountered with Caesarean sections were fetopelvic disproportion, fetal distress, malposition or malpresentation, pregnancy hypertension and uterine inertia. Neonates born by emergency section were more likely to be premature, or low birth‐weight and to manifest depression of vital signs compared with vaginal births. They also required more intensive resuscitation and neonatal care, and neonatal death occurred more frequently. Morbidity was much lower in neonates born by elective than emergency section.