DOG1 overexpression is associated with mismatch repair deficiency and BRAF mutations but unrelated to cancer progression in colorectal cancer

INTRODUCTION

The transmembrane channel protein DOG1 (Discovered on GIST1) is normally expressed in the gastrointestinal interstitial cells of Cajal and also in gastrointestinal stroma tumors arising from these cells. However, there is also evidence for a relevant role of DOG1 expression in colorectal cancers. This study was undertaken to search for associations between DOG1 expression and colon cancer phenotype and key molecular alterations.

METHODS

A tissue microarray containing samples from more than 1,800 colorectal cancer patients was analyzed by immunohistochemistry.

RESULTS

DOG1 immunostaining was detected in 503 (30.2%) of 1,666 analyzable colorectal cancers and considered weak in 360 (21.6%), moderate in 78 (4.7%), and strong in 65 (3.9%). Strong DOG1 immunostaining was associated with advanced pT stage (p=0.0367) and nodal metastases (p=0.0145) but these associations were not retained in subgroups of 1,135 mismatch repair proficient and 86 mismatch repair deficient tumors. DOG1 positivity was significantly linked to several molecular tumor features including mismatch repair deficiency (p=0.0034), BRAF mutations (p<0.0001), nuclear p53 accumulation (p=0.0157), and PD-L1 expression (p=0.0199) but unrelated to KRAS mutations and the density of tumor infiltrating CD8 positive lymphocytes.

CONCLUSION

Elevated DOG1 expression is frequent in colorectal cancer and significantly linked to important molecular alterations. However, DOG1 overexpression is largely unrelated to histopathological parameters of cancer aggressiveness and may thus not serve as a prognostic parameter for this tumor entity.

High density of cytotoxic T-lymphocytes is linked to tumoral PD-L1 expression regardless of the mismatch repair status in colorectal cancer

BACKGROUND

Immune checkpoint-inhibitors targeting the PD-1/PD-L1 system are FDA approved in microsatellite instable (MSI) or mismatch repair deficient (dMMR) colorectal cancer (CRC). PD-L1 expression is tightly linked to features connected to immune checkpoint inhibitor response, but studies on large subsets of cancers analyzing the correlation between different status of MSI/dMMR, tumor infiltrating lymphocytes and PD-L1 expression are still lacking.

METHODS

More than 1800 CRC were analyzed for PD-L1 by immunohistochemistry in a tissue microarray format. Data were compared to MMR, the number of intratumoral CD8⁺ cytotoxic T-cells, and adverse clinico-pathological parameters. Different cutoff levels for defining PD-L1 positivity in tumor cells (1%, 5%, 10%, and 50%) yielded comparable results.

RESULTS

At a cutoff level of 5%, PD-L1 positivity was seen in 5.1% of tumors. PD-L1 was more often positive in dMMR (18.6%) than in MMR proficient (pMMR) cancers (4.1%; p < 0.0001). The number of intratumoral CD8⁺ lymphocytes was strikingly higher in PD-L1 positive (939.5 ± 118.2) than in PD-L1 negative cancers (310.5 ± 24.8). A higher number of intratumoral CD8⁺ lymphocytes was found in dMMR CRC (PD-L1 positive: 1999.7 ± 322.0; PD-L1 negative: 398.6 ± 128.0; p < 0.0001) compared to pMMR CRC (PD-L1 positive: 793.2 ± 124.8; PD-L1 negative: 297.2 ± 24.2; p < 0.0001). In dMMR and pMMR CRC, PD-L1 expression in tumor cells was unrelated to tumor stage, lymph node status or lymphatic/venous invasion. PD-L1 positivity in tumor associated immune cells was seen in 47.5% of cases and was significantly linked to high numbers of tumor infiltrating CD8⁺, low tumor stage, and absence of lymph node metastasis and lymphatic/venous invasion (p < 0.0001 each).

CONCLUSION

The data support the previously suggested fact that PD-L1 expression in tumor cells is driven by extensive cytotoxic T-cell infiltration in highly immunogenic dMMR and pMMR CRC. Frequent and intense PD-L1 expression in tumor cells of dMMR CRC may contribute to the high response rates of dMMR CRC to immune checkpoint-inhibitors.

Elevated MUC5AC expression is associated with mismatch repair deficiency and proximal tumor location but not with cancer progression in colon cancer

Mucin 5AC (MUC5AC) is a secreted gel-forming mucin expressed by several epithelia. In the colon, MUC5AC is expressed in scattered normal epithelial cells but can be abundant in colorectal cancers. To clarify the relationship of MUC5AC expression with parameters of tumor aggressiveness and mismatch repair deficiency (dMMR) in colorectal cancer, a tissue microarray containing 1812 colorectal cancers was analyzed by immunohistochemistry. MUC5AC expression was found in 261 (15.7%) of 1,667 analyzable colorectal cancers. MUC5AC expression strongly depended on the tumor location and gradually decreased from proximal (27.4% of cecum cancers) to distal (10.6% of rectal cancers; p < 0.0001). MUC5AC expression was also strongly linked to dMMR. dMMR was found in 21.3% of 169 cancers with MUC5AC positivity but in only 4.6% of 1051 cancers without detectable MUC5AC expression (p < 0.0001). A multivariate analysis showed that dMMR status and tumor localization predicted MUC5AC expression independently (p < 0.0001 each). MUC5AC expression was unrelated to pT and pN status. This also applied to the subgroups of 1136 proficient MMR (pMMR) and of 84 dMMR cancers. The results of our study show a strong association of MUC5AC expression with proximal and dMMR colorectal cancers. However, MUC5AC expression is unrelated to colon cancer aggressiveness.

Ruptured pulmonary artery aneurysm mimicking pulmonary embolism

Aneurysms of the pulmonary artery are very rare pathological vascular conditions. Peripheral pulmonary aneurysms have been reported only in a few cases. The causes of these aneurysms include extensive degenerative changes, traumas, infection and congenital malformations. Because of the imminent danger of rupture, surgical treatment should always be preferred. The following case report demonstrates one of a multitude of possible misdiagnoses for rupture of a pulmonary aneurysm.

Vakuumtherapie beim Pleuraempyem - Erste Erfahrungen mit der Anwendung im Pleuraspalt

Meanwhile vacuum-assisted closure (V.A.C.) therapy belongs to the standard procedures in cardiovascular surgery. Its intra-thoracal application is mentioned in one unique case-report in literature. We like to show our first experiences with this technique demonstrating three cases with pleural infection. One patient with bronchial stump insufficiency, one with pleural empyema and one with penetrating abscess of the chest was treated with V.A.C.-therapy. We applied a combination of microporous silicon fleece and polyurethane foam in direct neighbourhood to ventilated lung areas inside the thoracic cavity. One patient died of metastasis of his cancer disease, while wound situation and bronchial stump insufficiency could be treated well. Two patients could be treated successfully and be discharged out of the hospital. No complications due to V.A.C.-therapy could be seen, such as fistulas of the lung or bleeding of the mediastinal organs. Intra-thoracal V.A-C.-therapy can be performed as a good therapeutic option in the treatment of septic diseases inside the chest.

Morphology of enkephalin-immunoreactive myenteric neurons in the human gut

The aim of this study was the morphological and further chemical characterisation of neurons immunoreactive for leu-enkephalin (leuENK). Ten wholemounts of small and large intestinal segments from nine patients were immunohistochemically triple-stained for leuENK/neurofilament 200 (NF)/substance P (SP). Based on their simultaneous NF-reactivity and 3D reconstruction of single NF-reactive cells, 97.5% of leuENK-positive neurons displayed the appearance of stubby neurons: small somata; short, stubby dendrites and one axon. Of these leuENK-reactive stubby neurons, 91.3% did not display co-reactivity for SP whereas 8.7% were SP-co-reactive. As to their axonal projection pattern, 50.4% of the recorded leuENK stubby neurons had axons running orally whereas in 29.4% they ran anally; the directions of the remaining 20.2% could not be determined. No axons were seen to enter into secondary strands of the myenteric plexus. Somal area measurements revealed clearly smaller somata of leuENK-reactive stubby neurons (between 259+/-47 microm(2) and 487+/-113 microm(2)) than those of putative sensory type II neurons (between 700+/-217 microm(2) and 1,164+/-396 microm(2)). The ratio dendritic field area per somal area of leuENK-reactive stubby neurons was between 2.0 and 2.8 reflecting their short dendrites. Additionally, we estimated the proportion of leuENK-positive neurons in comparison to the putative whole myenteric neuron population in four leuENK/anti-Hu doublestained wholemounts. This proportion ranged between 5.9% and 8.3%. We suggest leuENK-reactive stubby neurons to be muscle motor neurons and/or ascending interneurons. Furthermore, we explain why we do not use the term "Dogiel type I neurons" for this population.

[V.a.C.-therapy in abdominal surgery - experiences, limits and indications]

Compared to other surgical disciplines the significance of V.A.C.-therapy is rarely noticed in abdominal surgery. This may be due to uncertainty in defining clear indications or lack of technical know-how.

METHODS

We report on five selected septic cases in abdominal surgery without clearly defined indications for V.A.C.-therapy (ischiorectal abscess, perforation in Crohn's disease, pelvic abscess due to perforation caused by rectal carcinoma, abdominal compartment syndrome, anastomotic leak after rectal resection).

RESULTS

Regarding the individual aspects of indication, V.A.C.-therapy could be used successfully in the demonstrated cases. Under the palliative aspect, V.A.C.-therapy on a malignant wound bed allowed an early treatment with chemotherapy.

DISCUSSION

According to the literature dealing with V.A.C.-therapy, enterocutaneous fistulas, exposed viscera, enteral surfaces as well as malignancy in the wound bed are considered to be contraindications for the method. Reffering to our observations, these diagnoses should not be strictly regarded as contraindications. Elaboration of clear guidelines that point out clearly defined indications for V.A.C.-therapy should be the goal for the future.

[Prognostic risk factors in children and adolescents with craniocerebral injuries with multiple trauma]

220 of 268 polytraumatized patients (82.1%) presented an additional head injury, which increased the mortality significantly. By the Hannover Polytrauma Score we could demonstrate that the severity of the polytrauma and the prognosis depended on the extent of the brain injury. Important risk factors were skull fractures and shock on arrival. 66.7% of the patients with a severe brain trauma and a skull fracture died; without this fracture, only 36.8% died. 76.1% of the children with a systolic blood pressure (SBP) > 80 mm Hg survived, but only 31.2% with a SBF < or = 80 mm Hg did not die. For all polytraumatized children we recommend a computer tomography of the head. In spite of a negative initial CT a follow up CCT should be performed.