Change the values of an object's properties, depending on the property's name

I would like to change the value of targeted properties within my object depending on the property's name. Example:

// Returns a list of all the properties of an object
PropertyInfo[] properties = GetProperties(myObject);

// Set the values of all properties that contain "Show_" in their name to -1
foreach (PropertyInfo property in properties)
{
    if (property.Name.Contains("Show_"))
    {
        // update myObject's property value to -1
        // i.e. something like:
        // myObject.(property.Name) = -1;
    }
}

How would I go about doing this?

Thanks