Cannot retrieve inherited custom property value from AspNetUsers table

I use ASP.NET Identity 2.0 and create two different user entities inherited from ApplicationUser as posted on Implementing Inheritance with the Entity Framework 6 in an ASP.NET MVC 5 but I cannot reach these custom properties and its values (StudentNumber and Profession) while reaching custom properties defined in ApplicationUser (Name, Surname). And idea?

Here is the code I tried to use for retrieving value Name, Surname, StudentNumber and Profession:

Controller:

public AccountController(ApplicationUserManager userManager, 
    ApplicationSignInManager signInManager)
{
    UserManager = userManager;
    SignInManager = signInManager;
}

private ApplicationUserManager _userManager;
public ApplicationUserManager UserManager
{
    get
    {
        return _userManager ?? HttpContext.GetOwinContext()
            .GetUserManager<ApplicationUserManager>();
    }
    private set
    {
        _userManager = value;
    }
}


[AllowAnonymous]
public ActionResult ListAccount(JQueryDataTableParamModel param)
{
    var allUsers = UserManager.Users;
    //code omitted for brevity

    /* as there is no property StudentNumber and Profession in Users, 
    I cannot reach these properties while reaching other custom properties */ 
    var result = from c in allUsers 
select new[] { Convert.ToString(c.Id), c.Name, c.Surname, c.Email, c.PhoneNumber };
 }

Models:

public abstract class ApplicationUser : IdentityUser
{
    //snip
    //Common properties
    public string Name { get; set; }
    public string Surname { get; set; }
}

I defined different type classes and inherited from the base class:

public class StudentUser : ApplicationUser
{
    public string StudentNumber { get; set; }
}

public class ProfessorUser : ApplicationUser
{
    public string Profession { get; set; }
}