Samuli Vaittinen

Cdk5 regulates the organization of nestin and its association with p35

ABSTRACT The intermediate filament protein nestin is characterized by its specific expression during the development of neuronal and myogenic tissues. We identify nestin as a novel in vivo target for cdk5 and p35 kinase, a critical signaling determinant in development. Two cdk5-specific phosphorylation sites on nestin, Thr-1495 and Thr-316, were established, the latter of which was used as a marker for cdk5-specific phosphorylation in vivo. Ectopic expression of cdk5 and p35 in central nervous system progenitor cells and in myogenic precursor cells induced elevated phosphorylation and reorganization of nestin. The kinetics of nestin expression corresponded to elevated expression and activation of cdk5 during differentiation of myoblast cell cultures and during regeneration of skeletal muscle. In the myoblasts, a disassembly-linked phosphorylation of Thr-316 indicated active phosphorylation of nestin by cdk5. Moreover, cdk5 occurred in physical association with nestin. Inhibition of cdk5 activity—either by transfection with dominant-negative cdk5 or by using a specific cdk5 inhibitor—blocked myoblast differentiation and phosphorylation of nestin at Thr-316, and this inhibition markedly disturbed the organization of nestin. Interestingly, the interaction between p35, the cdk5 activator, and nestin appeared to be regulated by cdk5. In differentiating myoblasts, p35 was not complexed with nestin phosphorylated at Thr-316, and inhibition of cdk5 activity during differentiation induced a marked association of p35 with nestin. These results demonstrate that there is a continuous turnover of cdk5 and p35 activity on a scaffold formed by nestin. This association is likely to affect the organization and operation of both cdk5 and nestin during development.

Type and location of tumor‐infiltrating macrophages and lymphatic vessels predict survival of colorectal cancer patients

The type of tumor‐infiltrating macrophages may be decisive in tumor immunity, lymphangiogenesis and in the clinical outcome of cancer. Here, we elucidated the prognostic significance of lymphatic vessels, different types of macrophages and the balance between different macrophage types in colorectal cancer. We analyzed the impact of density, type and location of macrophages on the clinical behavior of 159 primary colorectal carcinomas using CD68 as a pan‐macrophage marker and CLEVER‐1/Stabilin‐1 as a marker for regulatory/suppressive macrophages. Podoplanin was used as a pan‐lymphatic vessel marker. A high number of CLEVER‐1/Stabilin‐1+ peritumoral macrophages positively correlated with survival (p = 0.04). However, in more advanced disease (Stage IV), the patients with a high number of peritumoral or intratumoral CLEVER‐1/Stabilin‐1+ macrophages had a shorter disease‐specific survival (p = 0.05, and p = 0.008, respectively). Moreover, a low number of suppressive intratumoral CLEVER‐1/Stabilin‐1+ macrophages among high numbers of CD68+ macrophages correlated with a low number of distant recurrences (p = 0.01) and to fewer disease relapses exclusively in the liver as well (p = 0.006). A high number of intratumoral lymphatics correlated with poor survival (p = 0.03). The results of this work suggest that the type of macrophages, number of lymphatic vessels and their location contribute to the clinical behavior of colorectal cancer in a disease stage‐specific manner.

Restoration of myofiber continuity after transection injury in the rat soleus.

In a shearing type of muscle injury, scar formation prevents restoration of myofiber continuity and the transected myofibers may become permanently divided into two separate myofibers. We have analysed whether the injured myofiber stumps can fuse and continuity of the transected fibers be re-established, if the stumps are surgically closely apposed immediately after injury. 55 rat soleus muscles were transected, after which the epimysium was carefully sutured and the leg was immobilised for seven days. The animals were sacrificed at 2, 5, 7, 10, 14 and 25 days after surgery. All muscles were analysed by light and electron microscopy as well as by immunohistochemistry. Mechanical strength was also measured at day 10 and 25. We observed that suturing reduced the extent of the intervening scar and accelerated healing. More importantly our results indicate that fusion of the stumps and thus restoration of myofiber continuity, is possible after myofiber transection injury.

Transected myofibres may remain permanently divided in two parts

During regeneration of transected myofibres a scar is formed between their stumps. Myofibres restore their tendon-muscle-tendon continuity and contractile function by attaching to the scar with new myotendinous junctions. The scar contracts with time, and thereby the stumps are pulled close to each other. During early regeneration, myoblasts and myotubes can fuse with the surviving parts of the transected myofibres. However, it is not known whether it is possible that the opposite stumps could eventually fuse to reunite the divided parts of the transected fibres. In this study, we show in rat that even after 12 months the stumps remain attached to the separating scar by myotendinous junctions without showing definite fusion of the stumps. We conclude that transected myofibres probably remain permanently divided in two consecutive tendon-muscle-tendon units.

Prognostic markers in stage I oral cavity squamous cell carcinoma.

Early‐stage oral squamous cell carcinoma (OSCC) treatment is based on anatomic location, clinical TNM staging, and histological grade. It is a heterogeneous disease group. Classification of patients with OSCC by immunohistochemical analysis of established oncoproteins and evaluate disease course was our primary objective. Characterization of stage I OSCC patients in Southwest Finland was our secondary objective.

Somatostatin receptor expression in lymphomas: a source of false diagnosis of neuroendocrine tumor at 68Ga-DOTANOC PET/CT imaging

Abstract Background: 68Ga-DOTANOC PET/CT is routinely used to image neuroendocrine tumors (NETs). A case of lymphoma initially thought to be NET based on a positive 68Ga-DOTANOC PET/CT was recently seen at our institution. This prompted us to determine prospectively somatostatin receptor (SSTR) status in patients with lymphoma by immunohistochemical analysis of SSTR subtypes 2, 3 and 5 (SSTR2,3,5) and 68Ga-DOTANOC PET/CT imaging. Material and methods: Twenty-one patients with newly diagnosed lymphoma were referred to 68Ga-DOTANOC and FDG PET/CT prior to any treatment. Tracer uptake was evaluated visually by two nuclear medicine specialists. Maximum standardized uptake values (SUVmax) were determined from 14 nodal and two extranodal regions with highest uptake in each patient. Lesions were then graded with Deauville score (1–5) on FDG PET/CT and modified Krenning score (0–4) on 68Ga-DOTANOC PET/CT, respectively. SSTR2,3,5 status was analyzed from routine biopsies of lymphomatous tissue and matched to corresponding PET/CT findings. Results: About 20/21 patients had FDG-positive lymphoma (Deauville score ≥3). Uptake of 68Ga-DOTANOC was regarded as positive if Krenning score was ≥2 and resulted in 13/21 (62%) patients having 68Ga-DOTANOC-positive lymphomas. The highest uptake of 68Ga-DOTANOC was seen in Hodgkin’s lymphoma of nodular sclerosis subtype and in diffuse large B-cell lymphoma (SUVmax median 9.8 and 9.7, respectively). Both cases showed strong SSTR2 immunopositivity in tumor cells. Some patients had SSTR2 immunopositivity predominantly in endothelial and dendritic cells and follicular centers of lymph nodes contributing to a positive PET/CT with probably low tumor-specific uptake. SSTR3 and SSTR5 were negative in most lymphoma subtypes. Conclusions: According to this pilot study, 68Ga-DOTANOC PET/CT is positive in some lymphoma subtypes which express SSTRs. These tumors present a potential risk of being misinterpreted as NETs if a representative tumor sample is not available. Lymphomas with high expression of SSTRs may be amenable to treatments targeting these receptors.

Epidemiological and treatment-related factors contribute to improved outcome of oropharyngeal squamous cell carcinoma in Finland

Abstract Background: Treatment for oropharyngeal squamous cell carcinoma (OPSCC) has changed, as the proportion of human papilloma virus (HPV)-related disease has increased. We evaluated nationwide information on its management and outcome during the treatment paradigm change period. Methods: We included all patients diagnosed and treated for OPSCC at the five Finnish university hospitals from 2000 to 2009. Patient records and pathology registries provided the clinicopathological data. p16 staining was performed on primary tumor samples of patients who had received treatment with curative intent. Results: A total of 674 patients were diagnosed and treated for OPSCC and the incidence increased along the study period. Of the evaluable tumors 58.5% were p16-positive and the number of p16-positive tumors increased along the years. The treatment was given with curative intent for 600 patients and it was completed in 564. Of them, 47.9% underwent primary surgery and 52.1% received definitive oncological treatment. Also, the treatment protocol changed towards a more oncological approach. Among patients treated with curative intent the five-year overall, disease-specific and disease-free survival rates were 60.1, 71.5 and 57.0%. In multivariate analysis, p16-positivity seemed to relate to reduced disease mortality in lateral and anterior-wall disease. Depending on primary tumor localization, also sex, classes T3–4, presence of regional metastasis and radiotherapy modality had an association with disease mortality. Conclusion: The incidence of p16-positive OPSCC and delivery of definitive oncological treatment increased in Finland during the study period. An improved survival outcome compared with the previous nationwide investigation was observed in this subset of patients.

Tumoral Expression of CD44 and HIF1α Predict Stage I Oral Cavity Squamous Cell Carcinoma Outcome

No biomarkers are used to estimate the prognosis in oral cavity squamous cell carcinoma (OSCC). In our previously published work, we have reported the prognostic value of CD44 and hypoxia inducible factor (HIF)−1α in patients with stage I disease.