Cancer-Associated Fibroblast Induces Acinar-to-Ductal Cell Transdifferentiation and Pancreatic Cancer Initiation Via LAMA5/ITGA4 Axis

BACKGROUND & AIMS

Pancreatic ductal adenocarcinoma (PDAC) is characterized by desmoplastic stroma surrounding most tumors. Activated stromal fibroblasts, namely cancer-associated fibroblasts (CAFs), play a major role in PDAC progression. We analyzed whether CAFs influence acinar cells and impact PDAC initiation, that is, acinar-to-ductal metaplasia (ADM). ADM connection with PDAC pathophysiology is indicated, but not yet established. We hypothesized that CAF secretome might play a significant role in ADM in PDAC initiation.

METHODS

Mouse and human acinar cell organoids, acinar cells cocultured with CAFs and exposed to CAF-conditioned media, acinar cell explants, and CAF cocultures were examined by means of quantitative reverse transcription polymerase chain reaction, RNA sequencing, immunoblotting, and confocal microscopy. Data from liquid chromatography with tandem mass spectrometry analysis of CAF-conditioned medium and RNA sequencing data of acinar cells post-conditioned medium exposure were integrated using bioinformatics tools to identify the molecular mechanism for CAF-induced ADM. Using confocal microscopy, immunoblotting, and quantitative reverse transcription polymerase chain reaction analysis, we validated the depletion of a key signaling axis in the cell line, acinar explant coculture, and mouse cancer-associated fibroblasts (mCAFs).

RESULTS

A close association of acino-ductal markers (Ulex europaeus agglutinin 1, amylase, cytokeratin-19) and mCAFs (α-smooth muscle actin) in LSL-KrasG12D/+; LSL-Trp53R172H/+; Pdx1Cre (KPC) and LSL-KrasG12D/+; Pdx1Cre (KC) autochthonous progression tumor tissue was observed. Caerulein treatment-induced mCAFs increased cytokeratin-19 and decreased amylase in wild-type and KC pancreas. Likewise, acinar-mCAF cocultures revealed the induction of ductal transdifferentiation in cell line, acinar-organoid, and explant coculture formats in WT and KC mice pancreas. Proteomic and transcriptomic data integration revealed a novel laminin α5/integrinα4/stat3 axis responsible for CAF-mediated acinar-to-ductal cell transdifferentiation.

CONCLUSIONS

Results collectively suggest the first evidence for CAF-influenced acino-ductal phenotypic switchover, thus highlighting the tumor microenvironment role in pancreatic carcinogenesis inception.

Metabolic Rewiring and Stemness: A Critical Attribute of Pancreatic Cancer Progression

Pancreatic ductal adenocarcinoma (PDAC) is one of the most aggressive diseases with a poor 5-year survival rate. PDAC cells rely on various metabolic pathways to fuel their unlimited proliferation and metastasis. Reprogramming glucose, fatty acid, amino acid, and nucleic acid metabolisms contributes to PDAC cell growth. Cancer stem cells are the primary cell types that play a critical role in the progression and aggressiveness of PDAC. Emerging studies indicate that the cancer stem cells in PDAC tumors are heterogeneous and show specific metabolic dependencies. In addition, understanding specific metabolic signatures and factors that regulate these metabolic alterations in the cancer stem cells of PDAC paves the way for developing novel therapeutic strategies targeting CSCs. In this review, we discuss the current understanding of PDAC metabolism by specifically exploring the metabolic dependencies of cancer stem cells. We also review the current knowledge of targeting these metabolic factors that regulate CSC maintenance and PDAC progression.

Elevated PAF1-RAD52 axis confers chemoresistance to human cancers

Cisplatin- and gemcitabine-based chemotherapeutics represent a mainstay of cancer therapy for most solid tumors; however, resistance limits their curative potential. Here, we identify RNA polymerase II-associated factor 1 (PAF1) as a common driver of cisplatin and gemcitabine resistance in human cancers (ovarian, lung, and pancreas). Mechanistically, cisplatin- and gemcitabine-resistant cells show enhanced DNA repair, which is inhibited by PAF1 silencing. We demonstrate an increased interaction of PAF1 with RAD52 in resistant cells. Targeting the PAF1 and RAD52 axis combined with cisplatin or gemcitabine strongly diminishes the survival potential of resistant cells. Overall, this study shows clinical evidence that the expression of PAF1 contributes to chemotherapy resistance and worse clinical outcome for lethal cancers.

PAF1 cooperates with YAP1 in metaplastic ducts to promote pancreatic cancer

Acinar-to-ductal metaplasia (ADM) is a precursor lesion of pancreatic ductal adenocarcinoma (PDAC); however, the regulators of the ADM-mediated PDAC development and its targeting are poorly understood. RNA polymerase II-associated factor 1 (PAF1) maintains cancer stem cells leading to the aggressiveness of PDAC. In this study, we investigated whether PAF1 is required for the YAP1-mediated PDAC development and whether CA3 and verteporfin, small molecule inhibitors of YAP1/TEAD transcriptional activity, diminish pancreatic cancer (PC) cell growth by targeting the PAF1/YAP1 axis. Here, we demonstrated that PAF1 co-expresses and interacts with YAP1 specifically in metaplastic ducts of mouse cerulein- or KrasG12D-induced ADM and human PDAC but not in the normal pancreas. PAF1 knockdown (KD) reduced SOX9 in PC cells, and the PC cells showed elevated PAF1/YAP1 complex recruitment to the promoter of SOX9. The PAF1 KD reduced the 8xTEAD and SOX9 promoter-luciferase reporter activities in the mouse KC (KrasG12D; Pdx-1 Cre) cells and human PC cells, indicating that the PAF1 is required for the YAP1-mediated development of ADM and PC. Moreover, treatment with CA3 or verteporfin reduced the expressions of PAF1, YAP1, TEAD4, and SOX9 and decreased colony formation and stemness in KC and PC cells. CA3 treatment also reduced the viability and proliferation of PC cells and diminished the duct-like structures in KC acinar explants. CA3 or verteporfin treatment decreased the recruitment of the PAF1/YAP1 complex to the SOX9 promoter in PC cells and reduced the 8xTEAD and SOX9 promoter-luciferase reporter activities in KC and PC cells. Overall, PAF1 cooperates with YAP1 during ADM and PC development, and verteporfin and CA3 inhibit ADM and PC cell growth by targeting the PAF1/YAP1/SOX9 axis in vitro and ex vivo models. This study identified a regulatory axis of PDAC initiation and its targeting, paving the way for developing targeted therapeutic strategies for pancreatic cancer patients.

Immunoglobulin classes, complement factors and circulating immune complexes in chronic sinusitis patients

Serum concentrations of immunoglobulin classes (IgG, IgA and IgM), complement factor B (FB), 4th complement factor (C4) and circulating immune complexes (CIC) were determined in 34 Nigerians with chronic sinusitis and 37 apparently healthy age and sex matched controls by single radial immunodiffusion and polyethylene glycol precipitation methods, respectively. The mean serum IgG, IgA, C4, FB and CIC were significantly reduced in chronic sinusitis patients compared with the controls. The mean serum levels of IgG, IgM, C4 and FB were higher in male chronic sinusitis patients compared with female patients. In contrast the mean serum level of IgA was significantly reduced in chronic sinusitis patients. Only IgG and IgA showed significant correlation with the duration of chronic sinusitis. These findings in Nigerian patients suggest immuno-deficiency as one of the causes of chronic sinusitis in Nigerians, therefore routine serum immunoglobulin evaluation is recommended and if found deficient immunoglobulin replacement therapy is advocated for the treatment of such chronic sinusitis.

Upper airway obstruction in Nigeria: an aetiological profile and review of the literature

The early history of tracheostomy and intubation suggested that upper airway obstruction had been in existence for a long time. A study of 80 patients with upper airway obstructions treated over a 10-year period between 1990 and 1999 was carried out to determine the aetiology and incidence. There were 65 (81%) males and 15 (19%) females with a sex ratio of 4.3:1 (M:F). The age ranged from 6 months to 70 years; with mean age of 27 years. Ninety-nine per cent were acquired causes and 1% were congenital. The commonest site of obstruction was in the larynx 81%. In children, the most common causes were laryngeal papilloma (16%) and foreign body (14%), while in adults, laryngeal carcinoma (24%) and direct laryngeal injuries (15%). The study revealed a wide range of causes of upper respiratory tract obstruction encountered in a developing tropical country. Health education and community awareness programmes should be supported. This would encourage early presentation, prompt referral to experts and earlier treatment with improved outcome.

Complications of sinusitis in Ibadan, Nigeria

Nowadays the complications arising from sinusitis are rare since the introduction of antibiotics. However sinusitis and its complications are still life-threatening and if neglected may result in high morbidity and mortality. It is the purpose of this study to draw attention to the effects of the spread of infection beyond the sinus wall and thus to influence the clinician in his management in order to prevent the subsequent spread of the disease, and secondly make him aware of the sinogenic origin of these complications when he sees them. A retrospective study of 90 patients with sinusitis seen over a ten year period between 1988 and 1997 in the ENT Department, University College Hospital, Madan was (lone and those that had complications were further analysed to meet the objectives of this study. There were 90 patients seen with sinusitis over the ten years period, out of which 33 (37%) cases had complications, 17 males and 16 females (M.F.1:1). The average age of cases with complications was 28 years (age range 2.5 - 75 years). 66.6% of the complications cases occurred in age group under 30 years of age. Thus children and young adults were mostly affected. Twenty-six cases (79%) of chronic sinusitis developed complications while in acute sinusitis there were 7 cases (21%). The site affected most commonly by complications was the orbit (41%) followed by Sinus wall (32%), orophyarynx (18%), intracranial (5%); no car complications were seen. The type of complications seen at various sites and their incidence were also highlighted. Thus with this study it is hoped that clinicians would be reminded that complications of sinusitis still occur and hence be aware of the necessity to recognize and prevent them as rapidly as possible to avoid serious consequences.

Pyogenic granuloma, a cause of congenital nasal mass: case report

This is a case report of a 45-day-old Nigerian boy who presented with obstruction of the left nasal cavity since birth caused by a pyogenic granuloma which was successfully removed.

Trends of sinusitis in Ibadan, Nigeria

Sinusitis occurs frequently, complications are infrequent since the introduction of antibiotics and mortality has also decreased significantly for same reason. A retrospective study of 90 patients with sinusitis seen over a 10 year period between 1988 and 1997 in the E. N. T. Department, University College Hospital, Ibadan was done to highlight the general direction and tendency of sinusitis in our environment. There were 50 (56%) males and 40 (44%) females. The average age was 33 years and 70% were under the age 40 years, showed that sinusitis affects mostly children and young adults. 38% in social class V while 10% social Class I. Chronic sinusitis was 93%, acute sinusitis 7% (both types unisinusitis 56%, pansinusitis 29%, multisinusitis 16%). All the cases of unisinusitis were maxillary sinusitis. 85 (94%) had surgical treatment (antrostomy 64%, Fronto ethmoi-dectomy 15%, Caldwell-Luc's 13%, antral lavage 13%). 80 (94%) patients are alive and well after 2 years of follow up, 5 (6%) lost to follow up. Complications arising from sinusitis was seen affecting the orbit in 41%--the largest, followed by sinus wall 32%, no ear complications seen. Thirteen (14%) of the sinusitis cases associated with allergy only, 24 (27%) with polyps only, 6 (1%) with both allergy and polyps. It stresses the interwoveness of these entities (allergy, Polyps, sinusitis)--one predisposes to the other. Thus with these trends of sinusitis being highlighted, it is hoped that this would enhance our knowledge of the pathology, diagnosis and treatment of sinusitis.

Ophthalmo-neurologic manifestation of nasopharyngeal carcinoma

Ophthalmo-neurologic manifestations may be the first and sole presenting feature of nasopharyngeal carcinoma. This may be mis-leading unless a high index of suspicion exists. A retrospective study with analysis of 79 patients with nasopharyngeal carcinoma seen in the 12 years between 1986 and 1997 is presented. Among the 79 cases seen and analysed 20 (25%) had ophthalmo-neurologic manifestations; showing that up to one quarter of nasopharyngeal carcinoma cases could have neuro-ophthalmic manifestations. The ages ranged between 11 years and 70 years with a male: female ratio 2.4:1. This is in consonance with previous reports that nasopharyngeal carcinoma mostly affects males. In this study, visual impairment and corresponding optic nerve lesions constituted 20% of the manifestations. Diplopia and ophthalmoplegia constituted 17% and 18% respectively of the manifestations; these are in consonance with previous reports as seen in literatures. However ptosis (15%) and Horner's syndrome (3%) were essential manifestations seen in this study that were not found or documented in other previous reports. It shows that these could be part of neuro-ophthalmic manifestations of malignant nasopharyngeal carcinoma prompting patients initial presentation to the ophthalmologist. This paper is thus to draw more attention to the significance of ophthalmo-neurologic signs and symptoms as an aid to early diagnosis of malignant nasopharyngeal carcinoma. This will no doubt improve prognosis.